Role of EMP2 in triple-negative breast cancer.

e13143 Background: Despite advances in therapeutic agents improving treatment outcomes, triple-negative breast cancer (TNBC) still needs more specific targeted treatments. Our previous studies highlighted DEL-1 as a potential therapeutic target and biomarker for TNBC. In this study, we demonstrated EMP2 as a down- stream of DEL-1 and as a regulator of stemness in TNBC. Methods: DEL-1expression was silenced using siRNA across multiple TNBC cell lines, followed by RNA sequencing to identify potential candidate gene groups. EMP2 was most upregulated in DEL-1 knockdown TNBC cell lines, and selected as the final candidate gene. Subsequent knockdown experiments targeting both DEL-1 and EMP2 were conducted to elucidate their roles in cellular functions. Furthermore, the expression of cancer stem cell markers, ALDH and Nanog, was evaluated after DEL-1 knockdown. Results: DEL-1 and EMP2 expression levels were all increased in TNBC cell lines compared to normal breast cell MCF10A. RNA sequencing revealed an inverse relationship between two genes, which was substantiated by separate knockdown experiments. Knockdown of EMP2 using siRNA in MB468 and MB231 resulted in decreased cell proliferation in both groups. Colony formation assays is conducted to evaluate the survival and proliferative capacity of individual cells, demonstrated improved colony formation in EMP2 knockdown group. In addition, we investigated the expression of cancer stem cell markers ALDH and Nanog in MB231 cells and found that their expression level increased after DEL-1 knockdown. Conclusions: This study demonstrated significant overexpression of DEL-1 and EMP2 in TNBC cell lines and revealed an inverse relationship between the two molecules. Plus, we found that EMP2 is associated with colony formation and suggest that this process occurs through the regulation of cancer stemness. In conclusion, we demonstrated that EMP2 functions down- stream of DEL-1 and act as a regulator of stemness in TNBC. Our findings suggest that EMP2 could be a promising therapeutic target for TNBC.