The work was led by the National Cancer Centre Singapore in collaboration with the A*STAR Institute of Molecular and Cell Biology, Singapore General Hospital and the Yong Loo Lin School of Medicine at the National University of Singapore. The peer-reviewed paper, “Identification of novel paracrine therapeutic targets in peritoneal metastases through integrative proteotranscriptomic analysis of ascites,” was published in Molecular Cancer on 11 September 2026.

Peritoneal metastases occur when cancers originating in abdominal organs spread to the peritoneum, the lining of the abdominal cavity. The source identifies gastric, colorectal and ovarian cancers as common primary sources, giving reported ranges of 20–25%, 20–45% and 60–75%, respectively. The condition is often diagnosed at Stage IV, has a median survival of under nine months and is frequently managed with palliative intent. Surgery, regionalised chemotherapy and systemic chemotherapy have limited curative ability.

Many patients with peritoneal metastases develop ascites, an accumulation of fluid in the abdomen. The 2026 study investigated the molecular pathways in this fluid that may support tumour development. It built on an earlier 2022 National Cancer Centre Singapore study, which had established that targeting ascites could inhibit tumour growth; the new analysis sought to characterise biological pathways and therapeutic vulnerabilities more comprehensively.

Using multiomic profiling, the team analysed proteins and biological pathways in a 397-sample ascites dataset spanning 21 primary cancer types. The collection is described by the researchers as one of the world’s largest ascites datasets. The analysis identified several paracrine factors implicated in tumour development, with PAI-1 and S100A10 emerging as key drivers in the ascites microenvironment.

The team selected PAI-1 as a therapeutic target because of its clinical and prognostic relevance in cancer progression. Instead of developing a conventional monoclonal antibody, the researchers created E8, a smaller antibody-derived drug known as a nanobody. The source notes that nanobodies have low immunogenicity and a reduced toxicity risk, and that these properties could support better tolerability than some existing treatments, although this was not established in patients in the reported experiments.

Investigators assessed E8 in three preclinical systems: in vitro cell assays, in vivo mouse models and ex vivo human tissue explants in which tumour tissue was grown in patients’ ascites. Across all three systems, E8 suppressed tumour growth with minimal toxicity. These findings support further investigation of E8 as a treatment directed at the ascites microenvironment, but the experiments do not demonstrate clinical efficacy, safety or patient benefit.

Associate Professor Johnny Ong, the study’s senior author and head of the Department of Sarcoma, Peritoneal and Rare Tumours at Singapore General Hospital and NCCS, said the work creates the possibility of a new class of treatments for peritoneal metastases that targets the tumour microenvironment through ascites rather than tumour cells directly. He said the pathway may have implications for cancers that result in ascites, including ovarian, gastrointestinal, liver, breast and lung cancers.

Dr Joe Yeong, co-author and principal investigator at A*STAR’s Institute of Molecular and Cell Biology, described E8 as a therapeutic candidate with potential to improve outcomes for patients who have limited treatment options. Professor Jimmy So of NUS Medicine said the research could help pave the way for effective therapy for peritoneal metastasis. These statements describe translational potential; the study itself was experimental and preclinical.

The researchers are working to advance E8 toward clinical-grade development and a first-in-human clinical trial. In parallel, they are developing a companion biomarker test to identify patients with elevated PAI-1 levels who may be most likely to benefit from E8. These efforts are part of the Melyorax Initiative, a newly established biologics research programme led by Ong, with E8 as its lead asset. Whether the suppression observed in laboratory and animal models will translate into clinical benefit remains to be established.

Subject of Research: Preclinical identification of ascites targets and testing of the E8 nanobody in peritoneal metastases

Article Title: SG research team develops novel nanobody targeting tumor-fueling fluid to treat late-stage cancer of the abdominal lining

Article References: SG research team develops novel nanobody targeting tumor-fueling fluid to treat late-stage cancer of the abdominal lining. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: peritoneal metastases, ascites, PAI-1, S100A10, E8 nanobody, tumour microenvironment, preclinical research, cancer therapeutics, Singapore, research, team, develops

The research drew on 393 adults aged 18 to 79 years enrolled in the Côte d’Ivoire dual burden of disease study, known as CoDuBu, which operates within the Taabo health and demographic surveillance system in the south-central part of the country. Roughly half of the participants were women, 55 percent lived in rural settings, and the vast majority were lifetime non-smokers who reported high levels of physical activity. Blood spots collected during health examinations were shipped to a biobank, where DNA was extracted, chemically converted and analyzed on an Illumina EPIC methylation array covering more than 866,000 genomic positions. After rigorous quality control, 841,953 CpG sites remained for the epigenetic age calculations, making this one of the most comprehensive methylation datasets ever assembled from this region of Africa.

From those methylation patterns, the team computed four of the most widely used epigenetic clocks. The first generation, HorvathAge and HannumAge, were trained purely on chronological age and estimate how old a person’s cells appear to be. The second generation, PhenoAge and GrimAge, incorporate clinical markers of disease and mortality, so they aim to capture not just age but the pace of health decline. For each clock, the researchers calculated epigenetic age acceleration, the residual difference between a person’s estimated biological age and their actual calendar age, adjusted where appropriate for the mix of white blood cells circulating in the sample. This acceleration measure is what researchers believe reflects the cumulative wear of environment, behavior and disease on the genome.

The headline result is reassuring: the clocks work. Correlations between epigenetic age and chronological age were strong across all four measures, with Pearson coefficients ranging from 0.83 to 0.93. Concordance statistics, which are stricter because they penalize systematic bias, were somewhat weaker, between 0.73 and 0.85, and the first-generation clocks outperformed the mortality clocks in raw age prediction. HannumAge was the most accurate, deviating from true age by an average of just under two years, while HorvathAge overestimated age by nearly six years on average. Each clock also showed a characteristic sweet spot where its predictions were sharpest: HannumAge performed best around age 32, HorvathAge around 62, and GrimAge around 78. These patterns mirror what has been reported in Ghanaian, South African and high-income cohorts, suggesting that the underlying biology of methylation aging is broadly conserved across human populations.

Yet the clocks are not interchangeable. Correlations between the acceleration measures themselves were surprisingly low, ranging from 0.24 to 0.66, which means each clock captures a partially distinct facet of biological aging. That distinction became vivid when the researchers examined which social and behavioral factors predicted faster aging. Men showed significantly higher acceleration than women on three of the four clocks, by roughly 1.6 to 2.9 years depending on the measure. Participants from the wealthiest households aged more slowly on the extrinsic and phenotypic clocks, an effect of about two years, consistent with the idea that economic security, healthcare access and nutrition buffer the genome against premature aging. High-risk alcohol consumption and smoking both accelerated the mortality-sensitive clocks, with smokers showing GrimAge acceleration of about 3.5 years.

Two of the most striking findings were non-linear. Physical activity and body mass index both showed U-shaped relationships with GrimAge acceleration, meaning that people at the extremes aged fastest. Underweight participants, who made up 7 percent of the sample, showed even stronger acceleration than those with obesity. In a setting where low body weight can reflect undernutrition, chronic infection and psychosocial stress rather than healthy leanness, this result suggests that the methylation clock registers the biological toll of deprivation just as faithfully as it registers the toll of metabolic excess. The authors also note a physical activity paradox: in populations where most activity comes from repetitive manual labor rather than leisure exercise, very high activity levels may promote chronic exhaustion and cardiovascular strain rather than protection, a pattern previously documented in large European studies.

The study then connected biological age to actual disease. About 22 percent of participants met the criteria for metabolic syndrome, and 56 percent had elevated fasting glucose, a strikingly high figure for a predominantly rural cohort. When the researchers regressed these outcomes on epigenetic age acceleration, they found that extrinsic acceleration and PhenoAge acceleration each increased the odds of metabolic syndrome severity by roughly 23 to 26 percent per standard deviation, and both were linked to high blood pressure and impaired fasting glucose. These associations held up after adjustment for demographic, socioeconomic and lifestyle factors, and for body mass index, indicating that the clocks carry information about cardio-metabolic risk beyond what conventional measures provide.

Perhaps the most mechanistically interesting result concerns what drives GrimAge. This clock is built from methylation surrogates of eight plasma proteins plus cumulative smoking exposure, and the team found that one component in particular, a methylation proxy for plasminogen activator inhibitor-1, or PAI-1, largely explained the clock’s associations with both risk factors and metabolic disease. The PAI-1 surrogate was associated with metabolic syndrome, high blood pressure, high triglycerides, central obesity and elevated glucose, and its links with lifestyle risks were robust to adjustment for blood cell composition. PAI-1 is a well-known player in inflammation, coagulation and metabolic dysregulation, and the authors argue that it may serve as a more reliable molecular marker of aging-related metabolic damage than the composite clock itself, a hypothesis they hope future studies will test.

The study has limitations that the authors acknowledge candidly. It is cross-sectional, so it cannot establish whether accelerated aging precedes disease or follows it, and the sample, though carefully characterized, is modest compared with the mega-cohorts of high-income epigenetics. The cohort was originally assembled to study asymptomatic malaria, although sensitivity analyses showed the results were stable when malaria cases were excluded. Even so, the work fills a conspicuous gap. Previous African validations, in Central African hunter-gatherers, South African men and Ghanaian migrants, covered narrow age ranges or specific subgroups; this study spans nearly six decades of adult life in both urban and rural settings and links methylation age to measured clinical phenotypes rather than self-report alone.

The broader implications are considerable. Populations across sub-Saharan Africa are aging rapidly while non-communicable diseases such as diabetes and hypertension rise in parallel with persistent infectious and environmental burdens, a double burden that could compress healthspan and push disease onset into ever-younger ages. If epigenetic clocks can be validated and eventually calibrated with African methylation data, they could become powerful tools for identifying which exposures, from poverty to alcohol to occupational strain, truly accelerate aging in transitioning societies, and for evaluating interventions before clinical disease emerges. The Côte d’Ivoire team argues that future longitudinal studies should fold in the wider exposome, including pollution, stress and sleep, to pinpoint the public health utility of these molecular hourglasses. For now, the message is clear: the clocks tick the same way in a rural Ivorian village as they do in a European clinic, and in both places, they are listening closely to how people live.

Subject of Research: Validation of DNA methylation epigenetic clocks and their cardio-metabolic risk associations in adults in Côte d'Ivoire

Article Title: Validity and cardio-metabolic risk profiles of DNA methylation clocks among adults in south-central Côte d’Ivoire

Article References: Sanchez, D., Jeong, A., Essé, C., Bassa, F. K., Koné, S., Acka, F., Laubhouet-Koffi, V., Kouassi, D., Utzinger, J., N’Goran, E. K., Bonfoh, B., Imboden, M., Holloway, J. W., & Eze, I. C. (2022). Validity and cardio-metabolic risk profiles of DNA methylation clocks among adults in south-central Côte d’Ivoire. Epigenetics Communications, 2(1), Article 1. https://doi.org/10.1186/s43682-022-00008-8

Image Credits: AI Generated

DOI: 10.1186/s43682-022-00008-8

Keywords: epigenetic clocks, DNA methylation, biological aging, Côte d'Ivoire, metabolic syndrome, GrimAge, PhenoAge, HorvathAge, HannumAge, non-communicable diseases, Africa, PAI-1

The SERPINE1 gene carries the instructions for producing a protein known as plasminogen activator inhibitor-1, or PAI-1. This protein is a central player in the body’s clotting and tissue-repair systems, but it also participates in inflammatory and fibrotic processes, including the scarring of tissue that follows injury or chronic irritation. The variant examined in the study is remarkably common, present in an estimated sixty percent of people. Because it is so widespread, any influence it exerts on asthma treatment response could affect a very large share of the pediatric asthma population, making the result potentially significant for clinical practice even before confirmatory trials are completed.

According to the study, the variant causes cells to produce more PAI-1 protein during a viral illness. That excess PAI-1 activity appears to have two consequences in the airway. First, it promotes more scarring of airway tissue, the kind of fibrotic remodeling that can permanently reduce lung function over time in children with severe or exacerbation-prone asthma. Second, it dampens the antiviral response, weakening one of the airway’s key defenses against the respiratory viruses that frequently trigger asthma attacks. Together, these effects help explain earlier observations that children carrying this variant are more likely to suffer asthma exacerbations when they catch viral infections.

The most striking element of the new work, however, concerns what happens when mepolizumab enters the picture. Mepolizumab is a monoclonal antibody that blocks interleukin-5, a signaling molecule that drives the development and survival of eosinophils, the white blood cells implicated in many cases of severe asthma. In patients without the SERPINE1 variant, the study found that the drug did not stimulate the damaging inflammatory changes observed during viral illness. In patients with the variant, by contrast, combining the drug with a viral infection appeared to activate additional inflammatory pathways that damage the airway. In other words, the same treatment that helps many children may, in the presence of this genetic background, be associated with more of the inflammation it is meant to control.

Senior author Rajesh Kumar, MD, Interim Division Head of Allergy and Clinical Immunology at Lurie Children’s and Professor of Pediatrics at Northwestern University Feinberg School of Medicine, framed the results as a mechanistic advance. He noted that previous studies had already linked the variant to a higher likelihood of asthma exacerbations during viral illness, and that the new findings offer a clearer understanding of how that increased risk arises. By tracing the pathway from gene to protein to airway inflammation, the study connects a population-level observation to a biological mechanism, which is the kind of evidence needed to justify genotype-guided treatment decisions.

The implications for precision medicine are considerable. Kumar emphasized that the findings may lead to future studies designed to identify patients for whom mepolizumab may not work as well, and who may even develop more of other types of inflammation that the drug does not block. Knowing this in advance, he argued, would allow clinicians to weigh alternative therapeutic options earlier in a child’s care rather than discovering a poor response only after months of treatment. Biologic therapies such as mepolizumab are expensive and require regular injections, so the ability to predict response from a genetic marker would spare families both the burden of ineffective treatment and the risks of uncontrolled disease.

For the study, Kumar and colleagues analyzed data and nasal samples collected from children aged six to seventeen with exacerbation-prone asthma who had participated in earlier research. Using nasal samples is a practical and informative approach in asthma studies because the lining of the nose reflects the mucosal environment of the respiratory tract, where viral infections first encounter airway tissue and where the earliest inflammatory events of an exacerbation unfold. Examining gene expression and protein activity in these samples allowed the team to observe, at the molecular level, how the SERPINE1 variant altered the airway’s behavior during viral illness and in the presence of mepolizumab.

Kumar was careful to note the limits of what the study can claim. The results show what is happening in the airway of patients with the variant during viral illness and in response to the drug, rather than what would be observed in clinical outcomes, because the study was not powered to reach a clinical conclusion. Sample size and study design constrain how strongly molecular findings can be translated into statements about exacerbation rates, hospitalizations, or symptom scores. Nevertheless, based on the known function of the inflammatory pathways involved, Kumar said he would expect that the presence of the variant in a child with asthma could translate into worse responses to mepolizumab in terms of asthma outcomes, a hypothesis that larger prospective trials would need to test.

The mechanistic picture that emerges is one in which a common genetic difference creates distinct responses to the same therapy. During a viral illness, children with asthma who carry the variant may experience more inflammation from the airway lining than children without it, and that underlying difference reshapes how the airway reacts when mepolizumab is administered. Because PAI-1 sits at the intersection of clotting, tissue remodeling, and inflammation, its overproduction during infection may tip the airway toward a profibrotic, poorly antiviral state that interleukin-5 blockade alone cannot correct. This may also explain why the drug does not block all the inflammatory activity observed in variant carriers: mepolizumab targets one specific immune pathway, while the variant-driven changes involve broader tissue-level processes.

Kumar described the work as a step toward treating asthma according to each child’s individual genetic makeup, and expressed enthusiasm about the potential of precision medicine to improve asthma outcomes for children. Asthma remains one of the most common chronic diseases of childhood, and exacerbation-prone asthma in particular imposes a heavy toll of emergency visits, missed school, and long-term lung function decline. If a routinely available genetic marker can flag children who are unlikely to benefit from a given biologic, clinicians could move toward earlier, better-matched therapies and avoid the trial-and-error that currently characterizes much of severe asthma management. The study, published in the Journal of Allergy and Clinical Immunology, adds to a growing body of evidence that the genetics of the airway’s repair and antiviral systems, and not only the immune pathways targeted by drugs, shape how children respond to asthma treatment.

Subject of Research: Effect of the SERPINE1 gene variant on children's inflammatory response to the asthma drug mepolizumab during viral illness

Article Title: Children with common genetic variant may have more inflammation in response to asthma drug

Article References: Children with common genetic variant may have more inflammation in response to asthma drug. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: asthma, SERPINE1, PAI-1, mepolizumab, pediatrics, precision medicine, viral illness, airway inflammation, biologics, genetic variant, eosinophils, exacerbations

The research, led by Hui Jeong An, Sung Hwan Cho, and colleagues at CHA University and CHA Bundang Medical Center, with corresponding authors Jin-Bae Kim of Kyung Hee University Hospital and Nam Keong Kim of CHA University, focused on four specific microRNAs: miR-10a, miR-30c, miR-181a, and miR-499b. MicroRNAs are short, non-coding RNA molecules, roughly eighteen to twenty-five nucleotides in length, that do not encode proteins themselves. Instead, they act as fine-tuners of gene expression. After being transcribed from the genome and processed through a well-characterized cellular machinery involving enzymes such as Drosha and Dicer, mature microRNAs are loaded into the RNA-induced silencing complex, where they bind to target sequences, typically within the three-prime untranslated region of messenger RNAs. This binding either promotes degradation of the target transcript or blocks its translation into protein. Because a single microRNA can regulate dozens or even hundreds of target genes, changes in microRNA sequence or abundance can ripple outward across entire biological pathways.

What makes microRNAs especially interesting from a genetic standpoint is that their genes themselves can harbor single nucleotide polymorphisms, or SNPs, which are positions in the DNA sequence where a single letter of the genetic code varies between individuals. When such a variant sits within the mature microRNA sequence or its precursor, it can alter how the microRNA folds, how it is processed, or which messenger RNAs it binds. In effect, these polymorphisms function as heritable knobs that dial the activity of gene regulatory networks up or down. Previous studies, including earlier work by some of the same Korean investigators on miR-146a, miR-149, miR-196a2, and miR-499 in the context of recurrent pregnancy loss, have suggested that such variants could plausibly influence reproductive outcomes, although findings across populations have often been inconsistent.

To interrogate this question systematically, the team enrolled 169 Korean women diagnosed with recurrent implantation failure and compared them against 281 fertile controls. Genomic DNA was extracted from peripheral blood samples, and the researchers genotyped four variants, denoted miR-10a A>T, miR-30c A>G, miR-181a T>C, and miR-499b A>G, using two complementary laboratory techniques: polymerase chain reaction with restriction fragment length polymorphism analysis, a classic method in which a variant either preserves or abolishes a restriction enzyme’s cutting site so that genotypes can be read from fragment sizes on a gel, and real-time polymerase chain reaction, which offers a faster, fluorescence-based genotyping readout. The study protocol received ethical approval from the Institutional Review Board of CHA Bundang Medical Center, and all participants provided written informed consent.

The first and perhaps most important analytical result was a negative one: when the researchers compared the overall RIF group with fertile controls, none of the four microRNA polymorphisms showed a statistically significant independent association with implantation failure risk. This kind of null result is common in complex-disease genetics and underscores why single-variant analyses frequently fail to capture the biology of multifactorial conditions. However, the picture changed when the investigators stratified the RIF group by clinical and laboratory characteristics. Among women who had experienced four or more failed implantation attempts, carriers of the miR-499b AG genotype showed a significantly elevated risk, with an adjusted odds ratio of 1.908 and a p-value of 0.021. Similarly, the miR-181a TC plus CC genotypes appeared to raise risk specifically among women with lower platelet counts, while the miR-30c AG plus GG genotypes consistently behaved in a protective manner, an effect that was particularly striking in subgroups of women with a body mass index of 25 kilograms per square meter or higher, where the adjusted odds ratio fell to 0.104, and in women with shorter activated partial thromboplastin times, where the adjusted odds ratio was 0.216.

These subgroup signals gain biological plausibility from what is already known about the targets of these microRNAs. PAI-1, the plasminogen activator inhibitor-1, is the principal inhibitor of tissue-type and urokinase-type plasminogen activators in the fibrinolytic system, and it is a confirmed target of miR-10a, miR-30c, and miR-181a, and a predicted target of miR-499b. PAI-1 is far from an arbitrary choice in a reproduction study. Successful implantation requires that trophoblast cells invade the endometrium in a tightly regulated fashion, a process that depends on a carefully choreographed balance between extracellular matrix degradation and coagulation control. Prior literature has linked PAI-1 expression to endometrial receptivity, to the invasive capacity of endometrial cells, and to disorders of female reproduction ranging from endometriosis to recurrent pregnancy loss. The PAI-1 4G/5G polymorphism has itself been studied in relation to implantation outcomes, and experimental work in endothelial and endometrial cancer cell models has shown that microRNAs of the 181 family and miR-10a can modulate PAI-1 levels and thereby influence fibrinolysis and cellular invasion.

Because of this mechanistic connection, the Korean team went beyond the conventional single-variant association analysis and tested whether combinations of microRNA polymorphisms and PAI-1 genotypes interacted synergistically to shape RIF risk. This type of multilocus analysis is statistically delicate, since the number of possible genotype combinations grows exponentially with each additional locus, but it can reveal gene-gene interactions that no individual variant analysis would detect. The results were striking. A three-locus combination involving PAI-1 and miR-181a, denoted the A-T-C combination, was strongly associated with susceptibility to RIF, with an odds ratio of 2.644, a p-value of 0.002, and a false discovery rate corrected p-value of 0.014, indicating that the signal survived correction for multiple testing. Conversely, a different combination, the G-T-G pairing of PAI-1 with miR-30c, was found exclusively among the fertile controls and was associated with a strong protective effect, with an odds ratio of just 0.055, a p-value of 0.002, and a false discovery rate corrected p-value of 0.014. In other words, women carrying that particular genetic configuration were dramatically underrepresented among those who experienced repeated implantation failure.

The authors are appropriately measured about the interpretive limits of their work. Certain multilocus allele combinations involving PAI-1 did show suggestive associations with RIF risk, but the estimates for rare combinations came with wide confidence intervals and, as the researchers themselves emphasize, should be treated as exploratory hypotheses rather than established findings. Genetic association studies in reproductive medicine have a checkered history of promising signals that fail to replicate, particularly when sample sizes are modest, as is nearly inevitable in a condition defined by a specific and relatively uncommon clinical presentation. The RIF group in this study comprised 169 women, a substantial number for this field but still small by the standards of genome-wide association research, and the cohort was restricted to Korean women, which raises questions about generalizability across ethnic groups where allele frequencies and linkage patterns may differ.

Nevertheless, the conceptual contribution of the study is significant. By anchoring the analysis in a defined biological axis, microRNAs that regulate PAI-1, the investigators moved beyond blind variant scanning and toward a pathway-informed framework for understanding implantation genetics. The protective effect of miR-30c AG plus GG genotypes in women with higher BMI and shorter aPTT, the risk effect of miR-499b AG among women with the most failed cycles, and the strongly interacting PAI-1 and miR-181a haplotypes all point toward the same underlying biology: the coagulation and invasion machinery of the endometrium, fine-tuned by post-transcriptional regulation, appears to be one of the determinants of whether an embryo can successfully establish a pregnancy. This is consistent with endometrial transcriptomic studies showing that microRNA expression profiles within the window of implantation differ between women with repeated failure and fertile individuals.

What might this mean clinically, and what should happen next? In the near term, nothing in this study supports routine genetic screening of IVF patients for these microRNA variants, since none of the individual polymorphisms predicted risk in the overall population and the stratified findings require independent validation. But the longer-term implications are tantalizing. If future studies in larger, multiethnic cohorts confirm that PAI-1 and microRNA genotype combinations stratify implantation failure risk, such information could eventually inform personalized protocols, guiding decisions about anticoagulation, endometrial preparation, or the intensity of preimplantation evaluation for women at high genetic risk. The study also reinforces a broader lesson that is reshaping human genetics: regulatory variation, including variation within microRNA genes, matters as much as variation within protein-coding sequences, and it is the architecture of interactions, not the influence of any single variant, that most often distinguishes patients from controls. Funded in part by Korea’s National Research Foundation, the Korea Health Industry Development Institute, and related agencies, and conducted under rigorous ethical oversight, this work offers the fertility research community a carefully documented set of hypotheses and a demonstration that the genetics of implantation, like implantation itself, is fundamentally a story of cooperation among molecular players rather than the performance of any one actor.

Subject of Research: Association of microRNA polymorphisms and PAI-1 gene-gene interactions with recurrent implantation failure in Korean women

Article Title: Association of miRNA (miR-10a, miR-30c, miR-181a, and miR-499b) Polymorphisms and Their Interactions with PAI-1 in Recurrent Implantation Failure in Korean Women

Article References: An, H. J., Cho, S. H., Ko, J. E., Kim, J. H., Park, H. W., Kim, Y. R., Ahn, E. H., Kim, J.-B., & Kim, N. K. (2026). Association of miRNA (miR-10a, miR-30c, miR-181a, and miR-499b) Polymorphisms and Their Interactions with PAI-1 in Recurrent Implantation Failure in Korean Women. Reproductive Sciences. https://doi.org/10.1007/s43032-026-02188-3

Image Credits: AI Generated

DOI: 10.1007/s43032-026-02188-3

Keywords: recurrent implantation failure, microRNA, PAI-1, single nucleotide polymorphism, in vitro fertilization, fertility genetics, gene-gene interaction, miR-181a, miR-30c, fibrinolysis, endometrial receptivity, Korean women

Peritoneal metastasis occurs when cancer cells detach from a primary tumor, most commonly of gastrointestinal, gynecological or appendiceal origin, and implant on the peritoneum, the membrane lining the abdominal wall and covering the organs within. As the disease progresses, many patients develop ascites, an abnormal buildup of protein-rich fluid that causes distension, discomfort and breathing difficulties. Clinically, the appearance of malignant ascites portends poor survival, yet the molecular contents of that fluid and their biological significance have remained surprisingly underexplored. Because ascites sits in direct contact with peritoneal tumor deposits, any signaling molecules it contains are, by definition, delivered to the tumor microenvironment, making it an ideal starting point for hunting paracrine factors, the secreted ligands that cells use to influence their neighbors.

To interrogate that signaling milieu systematically, the team assembled an extraordinary cohort: 397 samples of malignant cell-free ascites representing 21 distinct histological origins of peritoneal metastasis. Cell-free ascites, the liquid fraction left after cells and debris are removed, concentrates the soluble protein complement of the peritoneal cavity. The researchers applied quantitative mass spectrometry, using tandem mass tag labeling to measure protein abundance across large batches of samples with high reproducibility, complemented by rigorous quality control based on metrics such as coefficients of variation. This proteomic backbone was then integrated with transcriptomic data, allowing the team to confirm that the proteins they detected were not passive leakage from dying cells but were actively produced and secreted by defined cell populations within the tumor ecosystem.

The mass spectrometry analysis revealed multiple coherent biological themes woven through the ascites proteome. Chief among them was the coagulation cascade and its counterbalancing system, fibrinolysis, the enzymatic machinery that dissolves blood clots. The team identified both previously recognized paracrine factors and a set of novel candidates that appear amenable to therapeutic perturbation, including proteins such as S100A10, macrophage migration inhibitory factor, peroxiredoxin 1, phosphoglycerate kinase 1 and lactate dehydrogenase A. Each of these has known roles in tumor biology, from plasminogen activation and extracellular matrix remodeling to inflammatory signaling and metabolic adaptation, and their enrichment in ascites points to a peritoneal microenvironment actively shaped by tumor-driven secretion.

To determine which cells were responsible for producing the key ligands, the researchers turned to single-cell transcriptomic sequencing of cells recovered from peritoneal metastasis ascites. This analysis delivered one of the study’s most conceptually important findings: two functionally antagonistic regulators of fibrinolysis, S100A10 and plasminogen activator inhibitor-1, or PAI-1, are secreted by distinct cell populations within the tumor microenvironment. S100A10, which promotes plasmin generation and matrix degradation, and PAI-1, which inhibits it, sit on opposite sides of the fibrinolytic balance. Their co-elevation, attributed to separate cellular sources, indicates that upregulation of these ligands reflects active, coordinated secretion rather than passive homeostatic drift. In other words, the tumors and their stromal partners are not merely accumulating proteins; they are engineering the extracellular fluid to favor their own agenda.

Why would a cancer care about fibrinolysis? The answer lies in the mechanics of peritoneal spread. Plasmin activity remodels the extracellular matrix, clears fibrin barriers and facilitates cell motility, all processes that help disseminated tumor cells implant, invade and expand on peritoneal surfaces. By mapping the components of this system, including tissue-type and urokinase plasminogen activators, annexin 2, and their inhibitors, the study frames the ascites compartment as a regulated enzymatic workspace where coagulation and dissolution are choreographed to tumor advantage. That framing immediately suggests intervention points: if specific ligands sustain the peritoneal ecosystem, neutralizing them could degrade the environment on which the metastases depend.

The team went beyond cataloguing. They selected PAI-1, a well-studied but therapeutically elusive target, and engineered a nanobody, a single-domain antibody fragment derived from camelid heavy-chain antibodies, designed to bind and neutralize it. Nanobodies are roughly a tenth the size of conventional antibodies, offering deep tissue penetration, high stability and straightforward manufacturing, properties well suited to an intraperitoneal disease. Using surface plasmon resonance the researchers confirmed the nanobody bound PAI-1 with high affinity, and they then challenged it across a battery of preclinical models: in vitro assays with cancer and stromal cells, in vivo animal models of peritoneal metastasis, and ex vivo human explant systems that preserve fragments of actual patient tumor in their native architecture.

The results provided proof of concept that intercepting PAI-1 signaling can constrain peritoneal tumor growth with minimal toxicity. In the experimental systems, the anti-PAI-1 nanobody suppressed the fibrinolytic and pro-metastatic programs the multiomic analysis had flagged, while sparing normal physiology, an encouraging safety signal for a target embedded in the hemostatic system. Because PAI-1 is secreted into ascites and acts on neighboring cells, antibody-based neutralization is a rational modality: the drug circulates in the same fluid compartment where the ligand operates. The strategy also generalizes, since the same proteotranscriptomic pipeline that surfaced PAI-1 can be reapplied to the other paracrine factors the study identified, each now carrying a mechanistic rationale for drug development.

The broader significance of the work lies in its scale and integration. By pairing deep proteomics across nearly four hundred ascites samples and twenty-one tumor types with single-cell resolution attribution of ligand sources and functional validation in vitro, in vivo and ex vivo, the study demonstrates a template for target discovery in fluid-biopsied tumor microenvironments. It reframes malignant ascites from a prognostic liability into an analytical asset, a lens through which the signaling economy of peritoneal metastasis becomes visible. For a disease whose treatment options remain limited largely to cytoreductive surgery with hyperthermic intraperitoneal chemotherapy and systemic regimens of modest efficacy, the identification of actionable paracrine targets opens a genuinely new therapeutic front.

Considerable work remains before patients benefit. The nanobody must advance through formal preclinical development and clinical trials, biomarkers must be established to select patients whose tumors depend on PAI-1, and the logistics of intraperitoneal delivery will need clinical refinement. Yet the conceptual shift is already tangible. The study shows that the fluid bathing peritoneal tumors can be read, almost like a molecular transcript of the tumor’s intentions, and that reading it carefully reveals not just how the disease progresses but precisely where it is vulnerable. In turning the fluid of a poor prognosis into a map of therapeutic opportunity, the Singapore-led consortium has offered one of the more hopeful reframings of advanced abdominal cancer in recent years.

The scale of the ascites cohort deserves particular emphasis. Studies of malignant fluid have often been limited to a few dozen samples drawn from a single tumor type, making it difficult to distinguish cancer-specific signals from generic inflammatory noise. By sampling 397 specimens across 21 histological origins, the investigators could identify protein themes that recur regardless of whether the primary tumor arose in the stomach, ovary, colon or appendix, strengthening the case that the observed ligands reflect shared biology of the peritoneal metastatic niche rather than the idiosyncrasies of any one malignancy.

The choice of PAI-1 as the validation target also carries scientific weight. PAI-1, formally known as serpin E1, is a member of the serine protease inhibitor family and functions as the principal physiological brake on both tissue-type and urokinase plasminogen activators. Although elevated PAI-1 levels have been associated with poor outcomes in numerous cancers, the protein has historically been considered difficult to drug, partly because it interacts with multiple partners, including vitronectin, and because its role in hemostasis raises concerns about systemic interference. A nanobody format, with its compact size and high affinity confirmed here by surface plasmon resonance, offers one route around these obstacles, particularly when delivered locally into the peritoneal cavity where the ligand is concentrated.

The single-cell finding that S100A10 and PAI-1 originate from separate cell populations adds a layer of ecological interpretation to the fibrinolytic data. It implies a division of labor within the tumor microenvironment, in which different cellular compartments contribute opposing components of the same pathway, potentially allowing the tumor to tune plasmin activity spatially and temporally. Spatially resolved methods such as Stereo-seq, referenced in the study’s methodology, are increasingly enabling this kind of anatomical attribution of secreted signals.

Finally, the open-access release of the proteomic dataset itself represents a resource for the field. Researchers studying individual tumor types can query the ascites proteome for their own candidate ligands, extending the paracrine target list well beyond the factors validated in this initial report.

Subject of Research: Proteotranscriptomic identification of paracrine therapeutic targets in malignant ascites from peritoneal metastases

Article Title: Identification of novel paracrine therapeutic targets in peritoneal metastases through integrative proteotranscriptomic analysis of ascites

Article References: Liu, Y., Chong, C. Y. L., Wang, Y., Xu, L., Lim, H. J., Tan, Q. X., Hendrikson, J., Tan, J. W.-S., Ng, G., Guo, W., Wang, Y., Huang, L., Ge, W., Rethineswaran, V. K., Ong, J. Z. L., Quek, Y. E., Ang, A. J. Y., Teo, F., Chen, O. W., … Singapore Peritoneal Oncology Study (SPOS) Group and Singapore Gastric Cancer Consortium (SGCC) (2026). Identification of novel paracrine therapeutic targets in peritoneal metastases through integrative proteotranscriptomic analysis of ascites. Molecular Cancer. https://doi.org/10.1186/s12943-026-02787-3

Image Credits: AI Generated

DOI: 10.1186/s12943-026-02787-3

Keywords: peritoneal metastases, ascites, proteomics, PAI-1, S100A10, fibrinolysis, nanobody, paracrine signaling, single-cell sequencing, coagulation cascade, drug targets, Molecular Cancer