Abstract 3604: Epithelial Caveolin-1 regulates lung metastasis in advanced stages of breast cancer

Abstract Organotypic metastasis is a well-orchestrated sequence of events that takes place in tumors. The interplay between secretory factors from the primary tumor and the microenvironment of a distant organ determines the fate of metastasis. A significant concern in effective triple-negative breast cancer (TNBC) treatment is lung metastasis. Caveolin-1 (Cav-1), a lipid raft protein, is an important component of the metastatic interplay and is reported to be upregulated in the advanced metastatic stage of breast cancer. Although Cav-1 has been shown to have oncogenic potential, its role in TNBC lung metastasis is not fully understood. Our data illustrates, knocking out Cav-1 in the 4T1 cells (a mouse breast cancer cell line) affects cell morphology, extracellular vesicle formation, and MMP release in vitro. Furthermore, a wound healing/cell migration assay showed reduced migration in Cav-1 KO 4T1 cells when compared to control 4T1 cells, and these findings were validated using Cav-1 siRNA. For investigating the metastatic role, we injected Cav-1 KO 4T1 and control 4T1 cells into the mammary fat pad of female BALB/c mice, a syngeneic mouse model of triple-negative breast cancer. We found no evidence of lung metastasis in Cav-1 KO 4T1 injected mice when compared to control 4T1 injected mice. This was further supported by mRNA profiling of the tumor. We observed 21 epithelial cell migration genes that are differentially expressed in Cav-1 KO tumors when compared to WT tumors. Correlation analysis from Breast Cancer Gene-Expression Miner v4.8 (bc-GenExMiner), a human database, showed a significant correlation between Cav-1 expression and several of the 21 epithelial cell migration genes, along with integrin 3 alpha (ITGα3). Interestingly, in silico protein docking predicted an interaction between Cav-1 and ITGα3, which was later confirmed by co-immunoprecipitation. The role of ITGα3 in metastasis was further corroborated by cell migration assay, which was affected when siRNA was used to silence ITGα3 gene expression. Collectively, these findings provide evidence that Cav-1 KO, along with ITGa3, plays an important role in distant lung metastasis in the 4T1 tumor-induced mice model. Citation Format: Dhirendra Pratap Singh, Rashmi Pathak, Abhishek Pandit, Philip J. Ebenezer, Nithya Jambunathan, Sanjay Kumar, Alexander Du Plooy, Joseph Francis, Mary E. White. Epithelial Caveolin-1 regulates lung metastasis in advanced stages of breast cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3604.