Expression And Functions Of Ash1l In Liver Cancer

Hepatocellular carcinoma (HCC) is a common cancer and ranks the third lethal cancer worldwide. However, the detail molecular mechanisms underlying the initiation and progression of HCC remain poorly understood. Liver carcinogenesis is a multistep process that is driven by the accumulation of genetic and epigenetic alterations. Mutational landscape and driver mutations have recently been delineated by high-throughput sequencing studies. On the other hand, our current knowledge about epigenetic deregulation in human HCC is limited. Histone modification is a major component of epigenetic regulation, and deregulation of histone medication could alter local chromatin structure and gene expression. We hypothesized that deregulation of histone methyltransferases might contribute to HCC development. In this study, we showed that trithorax-group protein ASH1L was frequently up-regulated in human HCC. Overexpression of ASH1L was detected in 40% of primary HCCs and significantly associated with larger tumor size, present of venous invasion and tumor microsatellite formation. Up-regulation of ASH1L also correlated with increased Ki67 expression. ASH1L is a histone methyltransferase specific for catalyzing transcriptional-active H3K4 and H3K36 methylation. We showed that stable knockdown of ASH1L significantly suppressed HCC cell proliferation and colony formation. We further demonstrated that knockdown of ASH1L inhibited HCC cell migration. In addition, we investigated the underlying mechanisms contribute to ASH1L up-regulation. We showed that up-regulation of ASH1L in human HCC was contributed by chromosome amplification at chromosome 1q22. Furthermore, we showed that ASH1L was negatively regulated by miR-142. Therefore, down-regulation of miR-142 contributed to ASH1L up-regulation in HCC. In summary, our findings suggested that ASH1L was frequently up-regulated in human HCC due to chromosome amplification and miRNA deregulation. Citation Format: Lai Wei, Felice H. Tsang, Daniel Ho, Cheuk-Ting Law, Mengnuo Chen, Long-Hin Tsang, Carmen Cl Wong, Irene Ol Ng, Chun-Ming Wong. Expression and functions of ASH1L in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1380. doi:10.1158/1538-7445.AM2017-1380