Abstract 1674: Tripartite motif containing 28 (TRIM28) promotes breast cancer metastasis by stabilizing TWIST1 protein

Abstract Regulation of gene expression by TRIM28 is not only by transcriptional repression but also by post-translational regulation. Here we report that TRIM28 promotes breast cancer cell metastasis through TRIM28-TWIST1-EMT pathway. We find that TRIM28 is highly expressed in metastatic cancer cell lines and advanced breast cancer tissues. The expression of TRIM28 and TWIST1 is positively correlated with most of the invasive breast carcinomas. Notably, we find that overexpression of TRIM28 upregulates TWIST1 protein, whereas TRIM28 depletion downregulates TWIST1 protein, indicating that TWIST1 upregulation likely occurs at post-transcriptional level, not at transcriptional level. Overexpression of TRIM28 in BT549 breast cancer cell line promotes cell migration and invasion functionally; conversely, knockdown of TRIM28 reduces TWIST1 protein level, up-regulates E-cadherin and down-regulates N-cadherin, and consequently inhibits cell migration and invasion. Furthermore, Immunoprecipitation and GST pull down reveal that TRIM28 interacts with TWIST1 directly, thereby preventing from proteasomal degradation. Moreover, TWIST1 degradation rate is reduced after cycloheximide blocking protein synthesis through the depletion of TRIM28 in BT549 cells. Taken together, our findings suggest that TRIM28 functionally stabilizes TWIST1 protein, reveals a novel mechanism, and provides an effective therapeutic strategy to target TRIM28 in breast cancer treatments. Citation Format: Chunli Wei, Jingliang Cheng, Hanchun Chen, Dianzheng Zhang, Junjiang Fu. Tripartite motif containing 28 (TRIM28) promotes breast cancer metastasis by stabilizing TWIST1 protein. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1674.