Abstract 560: IGF1 induces the expression of CYR61 in metastatic prostate cancer

Abstract The cysteine-rich angiogenic inducer 61 (CYR61) is a member of the cellular communication network (CCN) protein family that can be induced by growth factors. CYR61-specific functions are dependent on cellular context. In prostate cancer (PCa), CYR61 contributes to cell growth and survival through its interactions with extracellular ligands, such as integrins avb3 and a6b4, in the extracellular matrix space. Interestingly, CYR61 contains an insulin-like growth factor-binding protein domain suggesting that it may interact with insulin-like growth factor-I (IGF1). High serum levels of IGF1 are directly linked to PCa development and recently have been studied as a predictor of metastatic disease. Given the important roles that IGF1 and CYR61 play in PCa and their potential interaction, it is critical to investigate their molecular interplay. The correlation between PCa aggressiveness and circulating levels of CYR61 and IGF1 is poorly studied. Our goal was to assess the contribution of CYR61-IGF1 interaction to PCa cell proliferation. Their combined role may explain a proportion of aggressive PCa. This study was designed to characterize the role of IGF1-induced expression of CYR61 in metastatic PCa cellular models and to determine if this interaction contributes to aggressive tumor properties (e. g. , proliferation, migration, tumorsphere formation). Using immunoblotting, we demonstrated that CYR61 is upregulated in the metastatic cell line PC3. Furthermore, optimized knockdown of CYR61 using siRNA significantly reduced PC3 cell proliferation, viability, and prostasphere formation. To examine the underlying mechanisms associated with IGF1 signaling, we assessed the activation of either the PI3/Akt and MAPK pathways in PC3 cells with CYR61 silencing. CYR61 siRNA-mediated knockdown decreased activation of the PI3/Akt pathway but did not affect the MAPK pathway. In addition, we found that IGF1 induces protein expression of CYR61 in a time-dependent manner, validated by both immunoblotting and confocal microscopy. In conclusion, these data provided evidence that CYR61 expression is induced by IGF1, and its inhibition decreased the capacity of metastatic PCa cells to proliferate, indicating a potential utilization of CYR61 inhibition in the therapy of metastatic PCa. Citation Format: Greisha L. Ortiz Hernandez, Mya Walker, Leanne Woods-Burnham, Rick A. Kittles, Carlos A. Casiano, Susan Neuhausen. IGF1 induces the expression of CYR61 in metastatic prostate cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 560.