The clinical backdrop is stark. Breast cancer is the most common malignancy in women, accounting for roughly 16 percent of all female cancers and standing as the leading cause of cancer-related death in this population. Like every solid tumor, a breast tumor cannot exceed a few millimeters in size without solving a supply problem: it must recruit blood vessels that deliver oxygen and nutrients and carry away waste. The canonical solution is angiogenesis, the growth of new capillaries from pre-existing vasculature, orchestrated above all by vascular endothelial growth factor (VEGF) and its receptors VEGFR1 and VEGFR2, which drive endothelial cell proliferation, migration, and survival, while the angiopoietins and their TIE receptors stabilize and mature the emerging network. In the modern formulation of cancer’s hallmarks, inducing and accessing the vasculature is a defining dimension of malignancy, and poor prognosis in breast cancer tracks closely with vascular alterations. Drugs that block the VEGF axis have transformed some areas of oncology, but in breast cancer their benefits have been modest and short-lived, largely because tumors activate vascularization strategies that the drugs never touch.

The most notorious of those strategies is vasculogenic mimicry. First described in highly aggressive melanomas and since reported across carcinomas, it describes the capacity of tumor cells to abandon their epithelial identity, drift toward an endothelial-like phenotype, and remodel the extracellular matrix into fluid-conducting channels that perfuse the tumor independently of normal blood vessels. Molecularly, the adhesion protein VE-cadherin is considered the gatekeeper: it recruits the receptor EphA2 to intercellular junctions, igniting the PI3K and ERK1/2 pathways that sustain tumor cell survival, proliferation, and migration. Matrix metalloproteinases — MMP-2 and MMP-9 in particular — carve these conduits out of the surrounding matrix. Because vasculogenic mimicry flourishes in hypoxic niches and correlates with resistance to anti-angiogenic therapy, identifying the signals that trigger it has become a central question in tumor vascular biology. The result, for patients, is a tumor that supplies itself with oxygen and nutrients while presenting drug developers with a moving target.

Leptin enters the story through the tumor’s own neighborhood. Breast tumors are enveloped in adipose tissue, and the cancer-associated adipocytes that dominate that microenvironment secrete leptin abundantly; the hormone is markedly overexpressed in the tumors of obese patients with estrogen receptor-positive disease. Building on the group’s earlier finding that leptin activates FAK in MCF-7 and MDA-MB-231 breast cancer cells — driving the secretion of MMP-2 and MMP-9, along with migration and invasion — and that the same axis triggers epithelial-to-mesenchymal transition in non-tumorigenic mammary epithelial cells, the team asked a bolder question: does leptin control tumor vascularization itself, and does FAK sit at the center of that control? They hypothesized that leptin regulates both angiogenesis and vasculogenic mimicry through a non-canonical FAK pathway, and assembled a battery of models to find out.

The anchor model was the chick chorioallantoic membrane (CAM), the densely vascularized extraembryonic membrane of fertilized chicken eggs, which allows blood vessel growth to be observed and manipulated directly. Filters soaked with leptin at 50 to 400 nanograms per milliliter were placed on the membrane with or without 5 micromolar PF-573,228, a selective FAK inhibitor, and after five days capillary sprouting, branching, and diameter were quantified morphometrically. In parallel, the researchers implanted 3 million MCF-7 or MDA-MB-231 cells in Matrigel onto the membrane to generate xenograft tumors, treated them with 500 nanograms per milliliter of leptin for 48 hours, and probed the excised tissue by confocal immunofluorescence for VEGF and N-cadherin and by histology for vessel number and caliber. A third arm grew the same cells on Matrigel, stained them with periodic acid-Schiff to expose vasculogenic mimicry structures, and used western blotting to track FAK phosphorylation at tyrosine 397 and a panel of angiogenic proteins. All experiments were performed with independent biological replicates, and only channels with clearly defined lumens were counted as mimicry structures, excluding mere cellular alignment.

On the CAM, leptin behaved as a textbook angiogenic factor, with a twist. Capillary sprouting rose measurably at 50 nanograms per milliliter and peaked at 200, reaching 13.33 sprouts against 2.67 in untreated membranes, while branching climbed dose-dependently from 10.67 to 22.67 branch points compared with a baseline of 5.67. Only the highest dose, 400 nanograms per milliliter, widened the vessels themselves, nearly doubling capillary diameter — evidence of vascular remodeling superimposed on new vessel growth. Low concentrations, in other words, elicit classical sprouting angiogenesis, whereas high concentrations appear to sculpt the existing vasculature, potentially enhancing perfusion, vascular permeability, and the escape of tumor cells into circulation. When FAK was inhibited, the entire program faltered: sprouting collapsed from 13.00 to 3.33 and branching from 18.67 to 6.00 at the 100-nanogram dose, and vessel caliber shrank at every leptin concentration tested. The kinase, the data suggest, is not a helper in leptin-driven angiogenesis but its pivot.

The xenografts revealed that the two breast cancer subtypes read the same hormone differently. Leptin raised VEGF and N-cadherin — an adhesion protein tied to invasion, therapy resistance, and metastasis to the liver, lungs, and lymph nodes — in both MCF-7 and MDA-MB-231 tumors. But the vascular architectures diverged. MCF-7 tumors, of the slower-growing luminal A subtype, responded to leptin with fewer vessels, 13.67 versus 23.50 per section, yet with vessels more than twice as wide, 128.7 versus 59.75 micrometers, a signature of structural remodeling that maintains perfusion without multiplying conduits. Triple-negative MDA-MB-231 tumors did the opposite: leptin increased both vessel density, from 17.50 to 23.33, and diameter, from 31.31 to 54.34 micrometers, in line with the intrinsically proangiogenic character previously documented for triple-negative cells. The luminal tumor rewires its existing network; the triple-negative tumor builds more of it.

Vasculogenic mimicry split along the same fault line. Grown on Matrigel, MCF-7 cells formed defined, lumen-containing tubular channels in a dose-dependent fashion, from 7.67 structures at baseline to 21.00 at the highest leptin dose, and the FAK inhibitor suppressed this tubular mimicry at every concentration tested — clear evidence of FAK dependence in the luminal model. MDA-MB-231 cells instead wove branched, matrix-type patterns into the extracellular matrix, which appeared from 50 nanograms per milliliter onward yet were wholly indifferent to FAK inhibition. Western blotting clarified the molecular underpinnings. In the triple-negative cells, leptin increased FAK phosphorylation and, in a FAK-dependent manner, raised TIE-1, MMP-9, VE-cadherin, angiopoietin-2, and VEGFR1 — a coherent pro-angiogenic, pro-mimicry portfolio — while VEGF itself rose independently of FAK, implicating alternative leptin-activated routes such as JAK2/STAT3, MAPK, NF-κB, and HIF-1α. In MCF-7 cells, the induction of MMP-9 required FAK, whereas angiopoietin-2 did not, and TIE-1 and VE-cadherin were unchanged. The researchers caution that mimicry identification rests on morphology and staining, and that future studies must confirm functional, perfusable lumens to rule out simple matrix deposition.

The translational implications are difficult to dismiss. Obesity drives leptin upward in proportion to fat mass, and hyperleptinemia is strongly associated with poor breast cancer prognosis, making the leptin–FAK axis an attractive therapeutic target, particularly in leptin-responsive tumors. The authors propose that combining FAK inhibitors with the anti-angiogenic drugs already in clinical use could yield additive or even synergistic effects by closing both escape routes simultaneously. They are equally candid about the caveats: the CAM assay, however elegant, lacks the immune and stromal complexity of human tumors; only two cell lines were examined, limiting extrapolation to other molecular subtypes; and no mammalian in vivo model was used, so systemic physiology remains untested. Orthotopic models and patient-derived xenografts, the team notes, will be essential to confirm the pathway’s role in living animals, and the variability of physiological leptin levels across metabolic states — obesity included — could reshape the magnitude of these responses in patients.

Conceptually, the study elevates leptin from metabolic bystander to active architect of tumor vascular plasticity: one hormone, two levers — angiogenesis and vasculogenic mimicry — pulled differently across two breast cancer subtypes with distinct survival strategies. It carries a poignant human footnote as well. The paper is dedicated to Dr. Napoleón Navarro-Tito, who conceived and directed the project at the Universidad Autónoma de Guerrero and died in July 2025, before seeing it published. If the leptin–FAK circuit is validated in patients, the work may come to be remembered as an early map of a vulnerability at the border between metabolism and malignancy — the exact point where the body’s energy reserves, quite literally, feed a tumor’s bloodline.

One of the most striking findings of the research is the identification of specific signaling pathways that are activated within the adipose tissue during obesity. These pathways create an environment that promotes cancer cell proliferation and survival. Specifically, the altered secretion of adipokines—bioactive substances released from adipose tissue—can significantly influence the tumor microenvironment. For instance, high levels of pro-inflammatory cytokines can induce a state of chronic inflammation that is known to foster tumorigenesis. This inflammation not only aids in the transformation of normal cells into cancerous ones but also assists in the progression of existing tumors.

Furthermore, the accumulation of visceral fat, particularly in the abdominal area, poses additional risks. The visceral fat depots are metabolically active and release fatty acids, hormones, and various inflammatory mediators into the systemic circulation. These substances can alter the function of distant tissues and organs, creating a systemic environment that is conducive to cancer progression. The interplay between visceral adipose tissue and cancer cells is complex, with both entities influencing each other’s behavior in ways that are just beginning to be understood.

The latest study also explores the role of hypoxia within the tumor microenvironment. Adipose tissue can undergo significant metabolic changes in the context of obesity, leading to localized hypoxic conditions that are detrimental to healthy cell functions. Cancer cells, however, exhibit remarkable adaptability to low-oxygen conditions, using alternative metabolic pathways to sustain their growth. This hypoxic state also enhances the aggressiveness of tumors by promoting epithelial-to-mesenchymal transition (EMT), a process that enables cancer cells to invade surrounding tissues more effectively.

In addition to metabolic changes, the presence of immune cells within adipose tissue also warrants attention. Obesity is associated with an altered immune profile, often characterized by increased infiltration of macrophages and other immune cells. These immune cells contribute to a pro-inflammatory environment that supports tumor progression. Notably, the interaction between cancer cells and immune cells in adipose tissue can lead to immunosuppression, allowing tumors to escape immune surveillance and thrive in hostile conditions.

The discovery of therapeutic targets arising from these microenvironmental interactions offers hope for innovative cancer treatments. For instance, targeting specific adipokines or inflammatory pathways may help to alter the tumor microenvironment in a way that stifles cancer growth. Current strategies under investigation include the use of anti-inflammatory agents and metabolic modulators aimed at normalizing the metabolic dysregulation associated with obesity. By doing so, it may be possible to not only slow tumor progression but also enhance the efficacy of existing cancer therapies.

The implications of these findings extend beyond the clinical realm, urging a broader public health conversation about obesity as a significant risk factor for cancer. Preventative measures that focus on maintaining a healthy weight may have an additional benefit of reducing cancer risk and improving outcomes for those already diagnosed. As our understanding deepens, proactive initiatives could emerge that emphasize lifestyle changes, dietary modifications, and increased physical activity as vital components in the fight against cancer.

Consideration of the socio-economic factors that contribute to obesity is also crucial in forming effective interventions. Disparities in access to healthy foods, recreational spaces, and healthcare resources can exacerbate obesity rates and, consequently, cancer risks. Addressing these systemic issues will be essential in reducing the incidence of obesity-related cancers and improving overall community health.

As ongoing research continues to unfold, interdisciplinary collaborations between oncologists, nutritionists, and public health experts will be pivotal in designing comprehensive strategies to tackle the obesity-cancer nexus. By integrating scientific insights with public health initiatives, there is potential for significant reductions in both the prevalence of obesity and its related cancer risks.

In summary, the intricate relationship between obesity, the tumor microenvironment, and cancer progression reveals a pathway for novel therapeutic strategies and public health initiatives. The microenvironment serves not only as a backdrop for tumor growth but also as an active participant in the progression of cancer during obesity. Subsequent research must continue to elucidate these complex interactions, paving the way for targeted therapies that address the unique challenges posed by the obesity epidemic in the context of cancer.

These insights underscore the urgency of addressing obesity as a major public health concern while highlighting the need for thorough understanding of its mechanisms in relation to cancer biology. In the coming years, as more studies emerge, the focus will likely broaden, incorporating the potential for integrative approaches that leverage advances in precision medicine against obesity-related cancer. The synthesis of these fields will not only aid in developing new treatments but also promote educational efforts aimed at creating healthier communities for future generations.

As we stand at this intersection of knowledge and emerging therapeutic strategies, the call to action remains clear: our fight against cancer cannot be divorced from our endeavor to combat obesity. With sustained efforts in research, public health policy, and community engagement, there exists a profound opportunity to make significant strides in reducing the burdens imposed by both cancer and obesity.

Subject of Research: The relationship between obesity and cancer progression, focusing on the microenvironment.

Article Title: Microenvironmental determinants of cancer progression during obesity: emerging evidence and novel perspectives.

Article References:

Salemi, R., Sergi, V., Basile, M.S. et al. Microenvironmental determinants of cancer progression during obesity: emerging evidence and novel perspectives.
J Transl Med 23, 995 (2025). https://doi.org/10.1186/s12967-025-06970-w

Image Credits: AI Generated

DOI: 10.1186/s12967-025-06970-w

Keywords: obesity, cancer progression, tumor microenvironment, adipokines, inflammation, immune response, hypoxia, therapeutic targets, public health.