Histone methylatic modification mediates the tumor-suppressive activity of curcumol in hepatocellular carcinoma via an Hotair/EZH2 regulatory axis.

ETHNOPHARMACOLOGICAL RELEVANCE: Curcuma kwangsiensis S. G. Lee & C. F. Liang (Guangxi ezhu, in Chinese) has been used as a traditional Chinese medicine (TCM) for approximately 2000 years. Curcumol is one of the major bioactive components of this herb, which has been demonstrated possesses anti-cancer properties, and was recorded in the Chinese Pharmacopoeia 2020 edition. However, most studies mainly focused on the superficial anti-cancer activity, the underlying mechanism remains poorly understood. AIM OF THE STUDY: In the present study, we aimed to investigate the anti-tumor effect of Curcumol on hepatocellular carcinoma (HCC), and elucidate its underlying mechanism from the perspective of epigenetic modification. MATERIALS AND METHODS: The potential anti-cancer properties of Curcumol were evaluated in HepG2 and SMMC-7721 cells. Its effects on cell growth, cell cycle, apoptosis and migration were examined in these HCC cells. Moreover, the lncRNA HOX transcript antisense intergenic RNA (Hotair) and histone methylatic modification were detected by qPCR and Western blotting assays. RESULTS: In the present study, Curcumol was illustrated to suppress cell growth in HCC cells via inducing apoptosis and cell cycle arrest. And it was also found that Curcumol inhibited the invasion and metastasis of HCC as well. As for the mechanism investigation, it was showed that lncRNA Hotair was significantly downregulated by Curcumol in HCC cells. As is well known, Hotair recruited histone methyltransferase enhancer of zeste homolog 2 (EZH2) to exert transcriptional regulation. Our results showed that EZH2 were downregulated by Curcumol in HCC cells, and thus disrupted the trimethylation of H3K9 and H3K27 which were specifically catalyzed by EZH2. CONCLUSIONS: In conclude, our results demonstrated that Curcumol suppressed tumor growth and metastasis via an Hotair/EZH2/histone modification regulatory axis.

Gallic Acid Suppressed Tumorigenesis by an LncRNA MALAT1-Wnt/ß-Catenin Axis in Hepatocellular Carcinoma.

Gallic acid (3,4,5-trihydroxybenzoic acid; GA), a natural phenolic acid, is abundantly found in numerous natural products. Increasing evidence have demonstrated that GA plays anti-cancer roles in multiple cancers. However, its anti-tumor effects on hepatocellular carcinoma (HCC) and the underlying mechanism remain obscure. In the present study, we found that GA suppressed the in vitro cell viability and metastasis and inhibited the in vivo tumor growth of HCC cells. The underlying mechanism was further to investigate and it was showed that GA suppressed the expression of ß-catenin and led to the functional inactivation of Wnt/ß-catenin signaling. As a kind of significant regulators, the long noncoding RNA molecules (lncRNAs) have attracted widespread attentions for their critical roles in diverse biological process and human diseases. To further identify which lncRNA participated this GA-mediated process, several lncRNAs related to Wnt/ß-catenin signaling were chosen for examination of their expression profiling in the GA-treated HCC cells. Of which, Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) was the most promising candidate. And moreover, MALAT1 was significantly down-regulated by GA. Its overexpression partially reversed the GA-induced the inhibitory effects on cell proliferation and metastasis; and successfully abolished the suppressive effect of GA on Wnt/ß-catenin signaling. In conclusion, our results indicated that GA suppressed tumorigenesis in vitro and in vivo by the MALAT1-Wnt/ß-catenin signaling axis, suggesting that GA has great potential to be developed as a chemo-prevention and chemotherapy agent for HCC patients.

H19-Wnt/ß-catenin regulatory axis mediates the suppressive effects of apigenin on tumor growth in hepatocellular carcinoma.

Hepatocellular Carcinoma (HCC) is one of the leading causes of cancer-related deaths in the world. However, the effective pharmacological approaches remain scanty in clinical practice. As a bioactive flavonoid, apigenin (API) is enriched in common fruits and vegetables. Although pharmacological activities of API have been widely investigated, its biological function in HCC remains obscure. In the present study, we found that API strongly suppressed cell growth and induced apoptosis in HCC cells. Using a xenograft mice model, API was demonstrated to inhibit the in vivo tumor growth. It is known that the long non-coding RNA H19, which is frequently elevated in HCC, plays a vital role in mediating tumorigenesis and cancer progression. Our results demonstrated that H19 was down-regulated by API, and thereby induced the inactivation of the canonical Wnt/ß-catenin signaling. In conclusion, our results demonstrated that API was able to suppress tumor growth of HCC through H19-mediated Wnt/ß-catenin signaling regulatory axis, suggesting that API may be a promising candidate for developing novel therapeutic approaches against liver cancer.