The thermogenic activity of adjacent adipocytes fuels the progression of ccRCC and compromises anti-tumor therapeutic efficacy

Clear cell renal cell carcinoma (ccRCC) preferentially invades into perinephric adipose tissue (PAT), a process associated with poor prognosis. However, the detailed mechanisms underlying this interaction remain elusive. Here, we describe a bi-directional communication between ccRCC cells and the PAT. We found that ccRCC cells secrete parathyroid-hormone-related protein (PTHrP) to promote the browning of PAT by PKA activation, while PAT-mediated thermogenesis results in the release of excess lactate to enhance ccRCC growth, invasion, and metastasis. Further, tyrosine kinase inhibitors (TKIs) extensively used in the treatment of ccRCC enhanced this vicious cycle of ccRCC-PAT communication by promoting the browning of PAT. However, if this cross-communication was short circuited by the pharmacological suppression of adipocyte browning via H89 or KT5720, the anti-tumor efficacy of the TKI, sunitinib, was enhanced. These results suggest that ccRCC-PAT cross-communication has important clinical relevance, and use of combined therapy holds great promise in enhancing the efficacy of TKIs.