Alzheimer’s disease is characterized by the progressive accumulation of amyloid-β, synaptic dysfunction, and inexorable cognitive decline, yet approved therapies remain largely symptomatic and incapable of halting neurodegeneration. Mounting evidence points to oxidative stress, mitochondrial dysfunction, and chronic inflammatory signaling as interconnected drivers of the disease process, creating a pressing need for interventions that target these pathways early. MicroRNAs—short, non-coding RNA molecules that fine-tune gene expression after transcription—have emerged as attractive candidates precisely because single microRNAs can modulate entire networks of stress-responsive genes. The obstacle has always been delivery: free microRNAs are rapidly degraded in biological fluids, are poor at crossing cell membranes, and lose their function before reaching intracellular targets.

Extracellular vesicles offer a natural solution to this delivery problem. These nano-sized, lipid-bilayer-bound packets are secreted by nearly all cell types and circulate in blood, cerebrospinal fluid, and milk, where they shield RNA cargo from enzymatic attack while ferrying it efficiently into recipient cells. The research team, led by neurologist Sinan Gönüllü of Bursa City Hospital and geneticist Selçuk Özdemir of Atatürk University, chose milk as the vesicle source for pragmatic reasons: milk-derived vesicles are biocompatible, exhibit low immunogenicity, carry intrinsic antioxidant and anti-inflammatory properties, and can be isolated at industrial scale—a combination of traits that synthetic nanoparticles have struggled to match.

The isolation protocol was rigorous. Sterile bovine milk was subjected to sequential centrifugation steps to strip away cells, fat globules, and protein aggregates, followed by ultracentrifugation at 100,000 × g to pellet the vesicles. The preparation was then polished through size-exclusion chromatography using qEV columns, and the final suspension was filtered through 0.22-micrometer membranes. Characterization followed the MISEV2018 guidelines: transmission electron microscopy revealed the classic round, cup-shaped vesicle morphology; dynamic light scattering placed the intensity-weighted size distribution around 190–200 nanometers; and nanoparticle tracking analysis showed peak diameters predominantly between 80 and 250 nanometers, with stock preparations containing roughly 10⁸ particles per milliliter.

Loading the vesicles with cargo required a chemical trick. The researchers incubated 1,000 micrograms of a synthetic miR-126-3p mimic with 200 micrograms of vesicle protein in the presence of 0.2 percent saponin, a mild detergent that transiently permeabilizes the vesicle membrane and allows the microRNA to enter. Unencapsulated RNA and residual saponin were then removed using PD-10 size-exclusion columns. Reverse transcription quantitative PCR confirmed that the microRNA was genuinely inside the vesicles rather than stuck to their surfaces: the signal survived treatment with RNase alone, which degrades only external RNA, but collapsed when RNase was combined with a membrane disruptor. Importantly, loading left vesicle morphology, size distribution, and colloidal properties essentially unchanged.

Why miR-126-3p? The choice rests on an accumulating body of mechanistic evidence. This microRNA is known to regulate vascular integrity and inflammatory signaling, dampening expression of adhesion molecules such as VCAM-1 and ICAM1, and it activates the SIRT1/Nrf2 antioxidant axis. Bioinformatic targetome analyses implicate it in neurotrophin and PI3K/AKT survival pathways, and experimental work has identified Alzheimer’s-relevant proteins—including BACE1 and EFHD2—as direct targets. In APP/PS1 mice, miR-126 overexpression reduces amyloid plaque burden and neuroinflammation, and circulating miR-126-3p has been reported as elevated in Alzheimer’s patients, marking it as an inflammation-associated biomarker of disease progression.

The disease model itself was deliberately conservative. Human SH-SY5Y neuroblastoma cells were exposed to oligomeric amyloid-β₁₋₄₂ at a sublethal dose of 0.5 micromolar for 24 hours—conditions chosen to elicit measurable redox and inflammatory alterations without outright cytotoxicity. Before therapeutic testing, an MTT viability assay established that the loaded vesicles were well tolerated at concentrations up to 5 micrograms per milliliter, corresponding to roughly 2.5 × 10⁶ particles per milliliter, while the highest tested dose of 10 micrograms per milliliter proved toxic. Four experimental groups were then compared: untreated controls, amyloid-β-exposed cells, amyloid-β-exposed cells given blank vesicles, and amyloid-β-exposed cells given miR-126-3p-loaded vesicles.

The results were striking in their breadth. Amyloid-β exposure drove intracellular reactive oxygen species, lactate dehydrogenase, glutathione peroxidase 1, and malondialdehyde sharply upward while suppressing superoxide dismutase activity—a signature of lipid peroxidation, membrane damage, and failing antioxidant defense. Blank vesicles produced only partial relief, but the miR-126-3p-loaded vesicles normalized essentially every oxidative parameter, returning values to statistically indistinguishable levels from healthy controls. The same pattern held at the transcriptional level: amyloid-β had upregulated the inflammatory genes ICAM1 and TNF-α and suppressed brain-derived neurotrophic factor, and only the loaded vesicles fully reversed this imbalance.

Mitochondrial and cytoskeletal readouts told an equally compelling story. Amyloid-β exposure elevated cytochrome c, 8-hydroxy-2′-deoxyguanosine (a marker of oxidative DNA damage), PINK1, and DNM1L, while reducing mitochondrial transcription factor A, indicating impaired mitochondrial DNA maintenance and dysregulated dynamics. Intracellular neurofilament light chain—an indicator of cytoskeletal stress in this cellular context rather than clinical axonal degeneration—soared with amyloid-β treatment and fell back to baseline only in the loaded-vesicle group. Synaptic and extracellular matrix-associated proteins followed suit: complexin 2 and SMOC1, which amyloid-β had depressed, and ROR1, which it had elevated, all normalized with miR-126-3p delivery. Finally, the hallmark molecular markers of Alzheimer’s pathology—total tau, phosphorylated tau at residues 181 and 217, and intracellular amyloid-β₁₋₄₀ itself—all rose sharply with amyloid-β exposure and returned to control-equivalent levels with treatment.

The authors are careful to frame these findings appropriately. SH-SY5Y cells are not fully differentiated, synaptically mature neurons, and the observed changes reflect modulation of stress-responsive gene programs rather than repair of brain tissue or reversal of established neurodegeneration. Several methodological gaps remain: the study lacked direct visualization of vesicle uptake, a scramble-miRNA control vesicle, free-miRNA comparison groups, and assessment of the broader mitochondrial biogenesis network involving PGC-1α, NRFs, and PARKIN. Downstream target validation of miR-126-3p within the cells also awaits future work. Validation in primary neuronal cultures, co-culture systems, brain organoids, and animal models will be essential before any translational claims can be made.

Even with those caveats, the study lands at a moment of intense interest in milk-derived vesicles as therapeutic carriers. Their lipid bilayers protect RNA payloads from ribonucleases in the bloodstream, their natural origin may allow them to navigate biological barriers with less immune pushback than synthetic vectors, and the raw material is abundant, inexpensive, and ethically uncontroversial. If miR-126-3p-loaded milk vesicles can retain their cytoprotective effects in living brain tissue—and, crucially, if they can cross the blood-brain barrier at therapeutically meaningful concentrations—the platform could open a non-invasive route for RNA-based modulation of the oxidative, inflammatory, and mitochondrial cascades that drive Alzheimer’s disease. For now, the image of a common dairy product yielding nanoscale couriers capable of quieting amyloid-β’s assault on human neurons is a vivid illustration of how therapeutic innovation increasingly borrows from biology’s own logistics network.

MicroRNAs influence virtually all hallmarks of cancer, including unchecked proliferation, evasion of apoptosis, angiogenesis, invasiveness, and metastatic dissemination. In lung cancer, aberrant expression profiles of miRNAs disrupt the delicate balance of oncogenes and tumor suppressor genes, tipping the scale toward malignancy. For example, miR-21, a well-characterized oncogenic miRNA, is consistently upregulated in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), where it promotes cell proliferation and inhibits programmed cell death by targeting multiple tumor suppressor transcripts. Its broad impact on pathways such as PTEN/PI3K/AKT underscores its pivotal role in enhancing tumor aggressiveness and chemoresistance.

The biogenesis of miRNAs is tightly controlled through a multi-step process beginning with transcription by RNA polymerase II, generating primary miRNA (pri-miRNA) transcripts. These transcripts undergo microprocessor complex-mediated cleavage by Drosha and DGCR8 within the nucleus to produce precursor miRNAs (pre-miRNAs), which are subsequently exported to the cytoplasm. There, the RNase III enzyme Dicer processes pre-miRNAs into mature miRNA duplexes. One strand, the guide strand, is incorporated into the RNA-induced silencing complex (RISC) to execute gene regulation. Dysregulation at any stage of this pathway – whether through genetic mutations, epigenetic modifications, or altered expression of biogenesis factors – results in miRNA imbalances that contribute substantially to lung carcinogenesis.

Exosomes, the extracellular vesicles secreted by tumor cells, carry miRNAs and other molecules that modulate the tumor microenvironment and facilitate metastatic niches. These exosomal miRNAs serve as messengers, reprogramming stromal cells, promoting angiogenesis, or suppressing immune surveillance. Detection of circulating exosomal miRNAs in plasma represents a promising non-invasive biomarker platform for early lung cancer diagnosis, monitoring therapeutic response, and predicting relapse.

The dichotomous nature of miRNAs in lung cancer is exemplified by their classification as either oncogenic (oncomiRs) or tumor-suppressive miRNAs. OncomiRs, such as miR-155 and miR-10b, stimulate tumor growth, invasion, and metastasis by targeting genes that regulate apoptosis and cell adhesion. Their overexpression often correlates with poor prognosis and advanced clinical stages. Conversely, tumor-suppressor miRNAs like miR-1 and miR-7 inhibit malignant transformation by repressing oncogenic signaling pathways, including the EGFR and KRAS cascades. The frequent downregulation of these miRNAs in tumor cells removes critical restraints on cellular proliferation and survival, accelerating cancer progression.

Therapeutic exploitation of miRNA pathways is an emerging frontier in lung cancer treatment. Strategies under investigation include the use of antagomirs or locked nucleic acid (LNA) inhibitors to silence oncogenic miRNAs, thereby restoring tumor suppressor gene activity. Alternatively, synthetic miRNA mimics can replenish lost tumor-suppressive miRNAs, reinstating their regulatory functions. Delivery approaches leveraging nanoparticle systems or exosome-mimetic vesicles are being optimized to enhance specificity and minimize off-target effects, addressing critical challenges in the clinical translation of miRNA-based therapies.

In addition to their therapeutic promise, miRNAs offer unprecedented potential as biomarkers for lung cancer screening and prognosis. Profiling miRNA signatures from patient-derived biofluids enables not only earlier detection of neoplastic changes but also stratification of patients based on likely treatment responsiveness. This fits within the broader framework of precision oncology, where individualized molecular landscapes inform personalized therapeutic regimens to maximize efficacy while limiting toxicity.

Despite the exciting progress, miRNA research in lung cancer faces significant complexity. The pleiotropic nature of miRNAs, often regulating multiple target genes across diverse pathways, necessitates comprehensive mapping of miRNA-mRNA interactomes within specific cellular contexts. Furthermore, the influence of tumor heterogeneity, epigenetic background, and external environmental factors complicates the delineation of causative versus correlative roles of miRNAs in cancer biology.

Further elucidation of the mechanisms governing miRNA expression and function in lung cancer will depend on integrative approaches combining high-throughput sequencing, single-cell analysis, and functional genomics. Such studies will be instrumental in uncovering novel miRNA regulatory circuits and their interplay with canonical oncogenic signaling networks. The integration of multiomics data promises to enhance our understanding of lung tumorigenesis and identify more robust molecular targets.

In sum, microRNAs represent powerful molecular switches that intricately regulate lung cancer development and progression. By manipulating miRNA networks, researchers hope to overcome the formidable therapeutic resistance and heterogeneity that have long stymied lung cancer management. As miRNA-based diagnostics and therapeutics advance toward clinical applications, they are poised to revolutionize the landscape of lung cancer care, offering hope for improved survival and quality of life in patients afflicted with this devastating disease.

Subject of Research: Oncogenic potential and regulatory roles of microRNAs in lung cancer pathogenesis and therapy.

Article Title: Unraveling the Oncogenic Potential of microRNAs in Lung Cancer: A Narrative Review Article

News Publication Date: 19-Mar-2025

Web References:

• https://www.xiahepublishing.com/journal/csp
• http://dx.doi.org/10.14218/CSP.2025.00001

Image Credits: Mohammad Bayat, Ali Moradi

Keywords: MicroRNA, Carcinogenesis, Target mRNA, Scientific publishing, Cancer screening