Abstract P6-14-18: Effect of 3q oncogene SEC62 on migration and proliferation of triple-negative breast cancer cells

Abstract Background Chromosome 3q26 amplifications represent a frequent alteration in various cancer entities including breast cancer. SEC62 – a 3q26 encoded gene – was identified as a potential onco- and tumor-driver gene for the pathogenesis of breast cancer. Although the precise physiological function of the respective protein Sec62 is not completely understood, Sec62 seems to induce an increased stress tolerance, enhanced cell migration and invasive potential in SEC62 overexpressing cells. SEC62 overexpressing breast cancer patients have been shown to have a higher rate of lymph node metastasis and poorer overall prognosis. Hence, we aimed to further evaluate the effect of Sec62 for triple-negative breast cancer by targeting cell migration and proliferation of triple-negative cell lines altered in their SEC62 expression. Objectives The aim of this study was to investigate the role of Sec62 for triple-negative breast cancer in cell culture using functional analyzes comparing cell migration and cell proliferation in triple-negative cell lines using the effects of siRNA-mediated Sec62 depletion in vitro. Material& Methods In this study, three SEC62 gene silencing experiments each with two different siRNAs directed against the SEC62 mRNA were carried out in comparison to a control siRNA in combination with cell proliferation and cell migration tests plus Western blots for the triple-negative breast cancer cell line CAL120 in order to determine the suspected causal relationship between SEC62- overexpression and an increased cell migration and thus an enhanced invasion potential of the cancer cells. The cell proliferation was examined in real time in the 96 well xCELLigence system and the cell migration using Fluoroblock without matrigel using fluorescence microscopy. Results In cell migration assays, the median migrated cell number in the control siRNA group was 263 (241-279), the cell number in the groups of the two siRNAs directed against the Sec62 mRNA was 72 (70-149) and 178 (96-276) (p < 0.01). In cell proliferation assays, the median cell index in the control siRNA group was 7.5 (7.4-7.6), while it was 7.4 (7.3-7 .5) and 7.6 (7.5-7.7) (p=0.37). In the first analyzes of the medians of the three gene silencing experiments of the cell line CAL120, the expected negative effect of the SEC62-siRNA on cell migration is confirmed, while, as expected, the effect on cell proliferation remains unchanged with decreasing Sec62 content. Conclusion In this in vitro study using cell migration and cell proliferation assays we found a correlation between SEC62 overexpression and increased cell migration. This implies a potential association between Sec62 and an increased tumor cell invasion in triple-negative breast cancer. Citation Format: Julia SM Zimmermann, Annika Cullmann, Askin Kaya, Merle Doerk, Maximilian Linxweiler, Marc P Radosa, Sven Lang, Martin Jung, Erich F Solomayer, Julia C Radosa. Effect of 3q oncogene SEC62 on migration and proliferation of triple-negative breast cancer cells [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-14-18.