Role of synaptotagmin 13 (SYT13) in promoting breast cancer and signaling pathways

ABSTRACT

Purpose Breast cancer is one of the leading causes of tumor death worldwide in female, and the five-year overall survival of breast cancer patients remains poor. It is an urgent need to seek novel target for its treatment. Synaptotagmin 13 (SYT13) is a synaptic vesicle transporting protein that regulates the malignant phenotypes of various cancers. However, its role in breast cancer is still unclear. The current study aimed to investigate the effects of SYT13 on the progression of breast cancer. Methods Twenty-five pairs of breast cancer tissues and non-tumor tissues were obtained to assess the expression of SYT13. We manually modified the expression of SYT13 in MCF-7 and MDA-MB-231 cells. CCK-8 assay, EdU staining, and cell cycle analysis were carried out to measure the proliferated ability of cells. Annexin V/PI and TUNEL assays were used to detect the apoptotic ability of cells. Wound healing and transwell assays were employed to evaluate the migrated and invasive ability of breast cancer cells. Results The results revealed that the mRNA and protein levels of SYT13 were higher in breast cancer tissues and cell lines. Knockdown of SYT13 inhibited the cell proliferation and induced cell cycle arrest in G1 phase of MCF-7 cells by downregulating cyclin D1 and CDK4, as well as upregulating p21. The migration and invasion of MCF-7 cells were repressed by the loss of SYT13 via the gain of E-cadherin and the loss of vimentin. Overexpression of SYT13 in MDA-MB-231 cells led to the opposite effects. Silencing of SYT13 induced the apoptosis ability of MCF-7 cells by the upregulation of bax and the downregulation of bcl-2. Moreover, we found that SYT13 depletion suppressed the FAK/AKT signaling pathway. PF573228 (a FAK inhibitor) and MK2206 (an AKT inhibitor) reversed the SYT13 overexpression-induced promotion of proliferation, migration, and invasion of MDA-MB-231 cells (AU)