Abstract 3643: HDAC6 modulates colon cancer cell migration and invasion

Abstract

Abstract Introduction: Non-histone protein acetylation in cancer cell regulates diverse biological functions that have been associated with tumorigenesis and cancer progression. HDAC6 is a tubulin-specific deacetylase which regulates microtubule-dependent cell movement. Here we investigated the role of HDAC6 on colon cancer progression. Methods: Colon tumor tissues were analyzed by immunohistochemistry to measure the expression of HDAC6. Attenuation of HDAC6 function was achieved using either inhibitors (Tubastatin and ACY-738) or siRNAs. Cell migration and invasion were determined using transwell assays. CCK8 and flow cytometry were used to assess the cell proliferation and cell survival respectively. We performed quantitative proteomic analyses to monitor changes in the abundance of protein lysine acetylation in response to HDAC6 deficiency. Immunoprecipitation assay was used to determine protein acetylation level and protein-protein interaction. Results: We identified that HDAC6 was highly expressed in metastatic colon cancer than non-metastatic colon cancer, indicating that HDAC6 is related with tumor metastasis. Selective suppression of HDAC6 or knocking down of HDAC6 significantly decreased colon cancer cell migration and invasion ability in vitro, without affecting cell proliferation and cell survival. In order to further clarify the role of HDAC6 in cell motility, we employed mass spectrometry-based label-free quantitative proteomics using human colon cancer cell line. We identified 42 proteins with > 2-fold increase of the acetylation level in the absence of HDAC6. These proteins are significantly enriched in processes related to cell-cell adhesion, cell division and several signaling pathways including cAMP and FoxO signaling pathway. We selected ENAH, an actin associated protein, as a potential new substrate of HDAC6, which has been previously reported to play important roles in cytoskeleton remodeling and cell polarity establishment. Immunoprecipitation analysis showed that HDAC6 can associate with ENAH under physical conditions. Besides, ENAH showed elevated acetylation in response to HDAC6 deletion. Conclusions: Our findings showed that inhibition of HDAC6 decreased the colon cancer cell migration and metastasis probably through regulating the acetylation level of ENAH. Our study also provided a resource of putative cytoplasmic targets of this deacetylase for further investigation. Considering that small molecule compounds targeting HDACs are currently undergoing clinical trials for the treatment of cancer, a better understanding of HDAC6-dependent cellular processes would be highly valuable for the evaluation of the clinical relevance and therapeutic efficacy of HDAC6 inhibitors. Citation Format: Hui Li. HDAC6 modulates colon cancer cell migration and invasion [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3643.