Stromal CAVIN1 Controls Prostate Cancer Microenvironment and Metastasis by Modulating Lipid Distribution and Inflammatory Signaling.

Lipid uptake occurs through caveolae, plasma membrane invaginations formed by caveolins (CAV) and caveolae-associated protein 1 (CAVIN1). Genetic alterations of CAV1N1 and CAV1 modify lipid metabolism and underpin lipodystrophy syndromes. Lipids contribute to tumorigenesis by providing fuel to cancer metabolism and supporting growth and signaling. Tumor stroma promotes tumor proliferation, invasion, and metastasis, but how stromal lipids influence these processes remain to be defined. Here, we show that stromal CAVIN1 regulates lipid abundance in the prostate cancer microenvironment and suppresses metastasis. We show that depletion of CAVIN1 in prostate stromal cells markedly reduces their lipid droplet accumulation and increases inflammation. Stromal cells lacking CAVIN1 enhance prostate cancer cell migration and invasion. Remarkably, they increase lipid uptake and M2 inflammatory macrophage infiltration in the primary tumors and metastasis to distant sites. Our data support the concept that stromal cells contribute to prostate cancer aggressiveness by modulating lipid content and inflammation in the tumor microenvironment. IMPLICATIONS: This study showed that stromal CAVIN1 suppresses prostate cancer metastasis by modulating tumor microenvironment, lipid content, and inflammatory response. ©2020 American Association for Cancer Research.