ABSTRACT
Altered DNA methylation is a crucial epigenetic event in hepatocellular carcinoma (HCC) development and progression. Through methylation-transcriptomic analysis, we identified a set of sixty potential DNA methylation-based epidriver genes. In this set of genes, we focused on the hypermethylation of EMX1, which is frequently observed in hepatobiliary tumors. Despite of its frequent occurrence, the function of EMX1 remains largely unknown. By utilizing bisulfite-next-generation sequencing, we have detected EMX1 DNA hypermethylation on the gene body, which is positively correlated with EMX1 mRNA expression. Further analysis revealed that EMX1 mRNA terminal exon splicing in HCC generated two protein isoforms: EMX1 full length (EMX1-FL) and alternative terminal exon splicing isoform (EMX1-X1). Cellular functional assays demonstrated that gain-of-function EMX1-FL, but not EMX1-X1, induced HCC cells migration and invasion while silencing EMX1-FL inhibited HCC cells motility. This result was further validated by in vivo tumor metastasis models. Mechanistically, EMX1-FL bound to EGFR promoter, promoting EGFR transcription and activating EGFR-ERK signaling to trigger tumor metastasis. Therefore, EGFR may be a potential therapeutic target for EMX1-high expression HCC. Our work illuminated the crucial role of gene body hypermethylation-activated EMX1-FL in promoting tumorigenesis and metastasis in HCC. These findings pave the way for targeting the EMX1-EGFR axis in HCC tumorigenicity and metastasis.
Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Humans , Carcinoma, Hepatocellular/pathology , DNA Methylation/genetics , Liver Neoplasms/pathology , Cell Line, Tumor , ErbB Receptors/genetics , ErbB Receptors/metabolism , RNA, Messenger/metabolism , Gene Expression Regulation, Neoplastic , Neoplasm MetastasisABSTRACT
PURPOSE: Our previous study showed that hepatic arterial infusion chemotherapy (HAIC) using oxaliplatin, fluorouracil, and leucovorin (FOLFOX) plus sorafenib provided a significant survival benefit over sorafenib for advanced hepatocellular carcinoma. However, it is unclear whether the survival benefit should be attributed to the synergism between HAIC and sorafenib or just HAIC alone. We aim to compare HAIC using FOLFOX plus sorafenib with HAIC alone in patients with advanced hepatocellular carcinoma. MATERIALS AND METHODS: This was a retrospective study including 225 eligible patients treated with HAIC using FOLFOX (HAIC alone group, n=126, oxaliplatin 85 mg/m², leucovorin 400 mg/m², fluorouracil bolus 400 mg/m² and 2400 mg/m² for 46 hours, every 3 weeks) alone or HAIC plus sorafenib (soraHAIC group, n=99, sorafenib 400 mg twice daily). Survival curves were calculated by the Kaplan-Meier method, and propensity-score matching was used to reduce bias. RESULTS: The soraHAIC group showed a longer overall survival (12.9 [95% CI, 10.4-15.4] vs. 10.5 [95% CI, 9.5-11.5] months, HR=0.71 [95% CI, 0.53-0.96]; P=0.025), a better progression free survival (7.0 [95% CI, 5.3-8.8] vs. 5.3 [95% CI, 3.5-7.1] months, HR=0.76 [95% CI, 0.58-0.99]; P=0.046), and a higher disease control rate (RECIST 1.1: 74.8% vs. 61.1%, P=0.030) than the HAIC alone group. In multivariate analysis, soraHAIC was an independent favor factor for survival. In terms of the grade 3/4 adverse event, hand-foot skin reaction was more frequent in the soraHAIC group than the HAIC alone group. In the propensity-score matched cohorts (93 pairs), the overall survival, the progression free survival and disease control rates in the soraHAIC group were also better than those in the HAIC group (P<0.05). CONCLUSION: HAIC plus sorafenib may improve overall survival and progression free survival compared with HAIC alone as initial treatment for advanced hepatocellular carcinoma.
