Abstract 4690: ARD1-mediated NRF2 acetylation promotes human colon cancer cell proliferation

Abstract

Abstract The transcription factor, nuclear factor erythroid 2-related factor 2 (NRF2) is regarded as one of the main orchestrators of the cellular antioxidant and carcinogen-detoxifying response. NRF2 plays a pivotal role in protecting normal cells from carcinogenic insults, but it may also accelerate the proliferation and progression of cancer cells. Abnormally elevated expression or activation of NRF2 has been attributed to mutation, especially in the sequences involved in interaction with its negative regulator KEAP1. However, other mechanisms responsible for NRF2 overactivation/overexpression are less well understood. Arrest defective (ARD1), an N-terminal acetyltransferase that catalyzes N-terminal acetylation of target proteins, has lysine acetyltransferase activity and is involved in mediating various (patho)physiological processes, such as proliferation, apoptosis, autophagy, and differentiation. Aberrant overexpression of ARD1 is correlated with metastasis and poor prognosis in several types of cancer, suggesting that it may act as a tumor promoter. In the present study, we found that NRF2, acteyl-NRF2, and ARD1 were highly expressed in some human colon cancer cell lines (HCT-116, HCT-15, DLD1) and tissues obtained from colorectal cancer patients. Furthermore, overexpression of NRF2 and ARD1 was also verified by quantitative immunofluorescence analysis of colorectal tissue microarray. We noticed that silencing of NRF2 and ARD1 individually in human colon cancer cells (HCT-116) led to the decreases in viability, anchorage-independent growth, and migration capacity of HCT-116 cells. While there was no change in the protein level of ARD1 when NRF2 expression was knock down by siRNA, protein expression of Nrf2 and acteyl-NRF2 was markedly reduced by silencing of the ARD1 gene. This prompted us to explore the association between ARD1 and NRF2 in the human colon cancer cell proliferation and progression. Co-immunoprecipitation and immunocytochemical analyses showed that two proteins colocalized in the cytosol, and ARD1 directly bound to NRF2. Taken together, ARD1 may potentiate the oncogenic function of NRF2 in human colon cancer cells by acetylating and stabilizing this transcription factor. This study was supported by the Global Core Research Center (GCRC) Grant (No. 2011-003-0001) from the National Research Foundation (NRF) of Republic of Korea. Citation Format: Xizhu Fang, Yeon-Hwa Lee, Jie Zheng, Seong Hoon Kim, Jeong-Hoon Jang, Do-Hee Kim, Young-Joon Surh. ARD1-mediated NRF2 acetylation promotes human colon cancer cell proliferation [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 4690.