Integrin α2β1 inhibition decreases angiotensin-converting enzyme (ACE) expression in renal cancer
Authors: Mia Md Saimon , Mia Md Saimon , Sun Dali , Mathew Sijo 
Published: May 2023

Background: Collagen1 is one of the most important extracellular matrix protein present in the tumor microenvironment (TME) of multiple solid tumors, including renal cancer. The increased collagen1 expression upregulates various cell signaling pathways, which promotes cancer growth, proliferation, and invasion. Integrin α2β1 is the primary subunit of the integrin superfamily that regulates collagen1 binding and signaling. The renin-angiotensin system (RAS) is predominantly expressed in the kidney cortex and is known for regulating blood pressure. Angiotensin-converting enzyme (ACE) is one of the major enzymes belonging to the RAS system and augments cancer progression by inducing angiogenesis and proliferation through the AT1 receptor (AGT1) mediated cell signaling. The role of increased collagen1 in the TME on ACE-mediated signaling in solid tumors is unknown. This study was undertaken to explore the significance of signaling from collagen1 through integrin α2β1 on the ACE-mediated mechanism that contributes to tumor growth. We hypothesize that inhibition of integrin α2β1 prevents tumor growth by decreasing ACE-mediated profibrotic cell signaling in renal cancer. Method: To test our hypothesis, integrin α2β1 inhibitor BTT 3033 and talin-1 shRNA was used to disrupt the signaling from collagen1 in the renal cancer cell, Caki-1. For talin-1 shRNA, puromycin selection was performed, and multiple clones (talin-1 knock-down cells) were picked up. Immunostaining was performed for total and active integrin β1 using AIIB2 and 12G10 antibodies, respectively. Immunoblotting and qRT-PCR were performed to observe different molecular changes. Results: BTT 3033 treatment significantly decreased the activation of integrin α2β1 (n=30, p<0.05) in Caki-1 cells without altering the total expression of integrins. BTT 3033 treatment also led to a significant decrease in ACE expression (n=3, p<0.05). Since talin-1 is one of the major activators of integrin α2β1, it was downregulated by shRNA. Downregulation of talin-1 led to a significant decrease in the integrin α2β1 expression and activation, leading to a 35% decrease in cell adhesion on collagen1. In addition, a significant decrease in focal adhesion was observed. The decreased integrin α2β1 inhibition also contributed to a significant decrease in ACE expression (n=3, p<0.05), AGT1 receptor expression (n=3, p<0.05), pro-proliferative signaling AKT phosphorylation (n=3, p<0.05) and ERK 1/2 phosphorylation (n=3, p<0.05) compared to the control cells. In summary, our study identified the significance of the integrin α2β1-ACE signaling in cancer progression through the AGT1 receptor. Conclusion: This study illustrates the mechanism of integrin α2β1 mediated tumor progression in renal cancer. National Institute of General Medical Sciences Award U54GM128729. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.