Abstract 4278: Role of WNK1 in extracellular matrix modification in breast cancer
Authors: Suman Prabhat , Kakkat Sooraj , Patil Suhas S. , Ramirez Veronica , Turbat-Herrera Elba A. , Singh Seema , Sarkar Chandrani , Chakroborty Debanjan 
Published: March 2024

Abstract
Introduction: Breast cancer (BCa) is the most common cancer and the second leading cause of cancer related deaths in women in the United States. Metastatic dissemination of cancer cells remains the leading cause of mortality in BCa. Therefore, determination of the mechanisms that promote metastasis is important for development of new therapeutic strategies. The extracellular matrix (ECM), which is the main non-cellular component of the tumor microenvironment (TME), plays an important role in BCa progression and metastasis. The cancer-associated fibroblasts (CAFs) are the principal cell types that together with BCa cells drive the modification of ECM during cancer development. Lysine deficient receptor protein kinase 1 (WNK1), a widely expressed serine threonine kinase that regulates blood pressure and electrolyte balance in the body, and is highly overexpressed in BCa microenvironment. The aim of the present study was to investigate the role of WNK1 in modification of ECM in BCa.
Methods: The clinical relevance of WNK1 overexpression in BCa was determined by immunohistochemically staining human BCa sections, analyzing data from publicly available databases and creating orthotopic mouse models of BCa using 4T1 mouse BCa cells followed by treatment of the tumor bearing mice with WNK1 inhibitors, WNK-IN-11 and WNK463 (10 mg/kg , oral for 10 days). In vitro assays were conducted using 4T1 cells and mouse embryonic fibroblasts (MEFs) to determine the regulatory role of WNK1 on cancer cells and fibroblasts.
Results and Conclusion: Our results indicated that WNK1 is strongly expressed in BCa cells and fibroblasts, the two most abundant cell types in the BCa microenvironment. Furthermore, WNK1 expression strongly correlated with expressions of matrix regulatory and cross-linking genes. Our results demonstrated that WNK1 inhibitors significantly reduced orthotopic 4T1 growth and metastasis. WNK1 inhibition also significantly inhibited collagen deposition in tumor tissues, which is a negative prognostic indicator in BCa. In vitro proliferation and migration assays using 4T1 cells and MEFs identified that WNK1 inhibitors (1-100nM) can significantly inhibit the proliferation and migration of 4T1 cells and MEFs. Results from co-culture studies with 4T1 cells and MEFs further indicated that WNK1 inhibition in MEFs could significantly reduce the invasive properties of 4T1 cells. Taken together, our results suggest that blocking the actions of WNK1 in BCa may be a promising therapeutic approach.
Citation Format: Prabhat Suman, Sooraj Kakkat, Suhas S. Patil, Veronica Ramirez, Elba A. Turbat-Herrera, Seema Singh, Chandrani Sarkar, Debanjan Chakroborty. Role of WNK1 in extracellular matrix modification in breast 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(6_Suppl):Abstract nr 4278.