Abstract P2-01-16: CRISPR-Cas9 screen identifies TMEM106A as a suppressor of breast cancer metastasis

Purpose: Breast cancer is one of the most common malignancies among women. The majority of cancer-associated deaths are caused by metastasis. Many biological alterations occur during this complex process, including the epithelial-mesenchymal transition (EMT), tumor immune escape, transendothelial migration (TEM). However, the biological mechanism of metastatic disease remains poorly understood and more need to be done to unify our understanding of underpinnings for metastasis in breast cancer. Methods: We performed functional screening with CRISPR-Cas9 Genome-Scale CRISPR Knock-Out (GeCKO) library to identify metastasis-associated genes in breast cancer. We confirmed the function of a set of genes by transwell assays to testify the efficacy of in vivo screening. Further, we conducted in vitro and in vivo assays to explore the mechanism of TMEM106A in suppressing metastasis of breast cancer. Results: The CRISPR-Cas9 library screening identified genes with potential of suppressing metastasis in breast cancer. Further validation of COPS2, SSBP2, TDG, DYRK4, GSG1, TMEM106A and PRR5L revealed that knock down of these genes promoted cell migration and invasion ability. In MDA-MB-231 and MDA-MB-468 cells, knock down of TMEM106A promoted in vitro migration, invasion, wound healing and in vivo pro-metastasis ability. In addition, E-cadherin was down-regulated and N-cadherin was up-regulated with suppression of TMEM106A. Accordingly, the potentiality of pro-metastasis was reversed when exogenous TMEM106A was expressed in MDA-MB-231 and MDA-MB-468 cells. We found the interaction between TMEM106A and WDR77 via Co-IP and MS analysis. Down-regulation of TMEM106A promoted expression of WDR77, which primarily occurred in the cytoplasm. To verify the association between TMEM106A and WDR77, we interfere WDR77 expression in MDA-MB-231 sg-TMEM106A, and the pro-metastasis effect of TMEM106A down-regulation was reversed. Discussion: CRISPR-Cas9 library screening is an effective strategy to identify genes associated with breast cancer metastasis. The positive selection provides us a set of genes with potentiality to repress migration and invasion. TMEM106A may suppress metastasis via influencing translocation of WDR77 in breast cancer. Citation Format: Yang L, Yu S-J, Shao Z-M. CRISPR-Cas9 screen identifies TMEM106A as a suppressor of breast cancer metastasis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-16.