Adipose tissue and renal carcinoma: a protumor metabolic and endocrine alliance

Abstract

Background Cancer is a multifactorial disease influenced not only by genetic and epigenetic alterations but also by interactions with the surrounding microenvironment. Among the hallmarks of cancer, metabolic reprogramming enables tumor cells to adapt and survive under adverse conditions. These metabolic alterations also induce changes in stromal cells. In clear cell renal cell carcinoma (ccRCC), adipocytes are among the most abundant stromal components. We have previously shown that ccRCC progression depends on the bidirectional crosstalk between tumor epithelial cells and neighboring adipocytes. Here, we investigated the effects of ccRCC on naïve human adipose tissue (hRAN). Methods Human retroperitoneal adipose tissue fragments were incubated with conditioned media (CMs) derived from ccRCC tumors (T-CM) or renal epithelial cells (Tc-CM). We analyzed the expression of adipocytokines, differentiation and browning markers, metabolic parameters, and steroid hormone receptor profiles. Results Exposure of hRAN to T-CM or Tc-CM led to significant alterations in the expression of adiponectin and leptin, as well as markers associated with differentiation and browning, including PLIN1, HSL, PGC1α, PPARγ, and UCP1. Adipocytes from treated hRAN were smaller than those from controls, suggesting dedifferentiation. Moreover, expression of FABP4 and MCT1 was significantly increased in explants treated with T-CM compared to control media. Conditioned media from these treated hRAN samples showed elevated lactate secretion, indicating enhanced lactatogenesis. Given the role of sex hormones in metabolic regulation, we examined the expression of estrogen (ER), androgen (AR), and progesterone (PR) receptors. While AR and PR levels remained unchanged, both ERα and ERβ were significantly up regulated after T-CM treatment. Conclusion Metabolic reprogramming in renal tumors induces profound adaptive changes in adjacent adipose tissue. The dedifferentiation and browning of adipocytes, altered adipocytokine expression, and increased lactate production observed in hRAN reflect the metabolic stress imposed by the tumor environment. This study provides, to our knowledge, the first evidence of a bidirectional interaction between human adipose tissue explants and ccRCC tumors using in vivo and ex vivo models.