Targeting the Epigenetic Non-Coding RNA MALAT1/Wnt Signaling Axis as a Therapeutic Approach to Suppress Stemness and Metastasis in Hepatocellular Carcinoma

• Published in: Cells (Basel, Switzerland) Switzerland), 2020-04, Vol.9 (4), p.1020
• Main Authors: Chang, Hang-Lung, Bamodu, Oluwaseun Adebayo, Ong, Jiann-Ruey, Lee, Wei-Hwa, Yeh, Chi-Tai, Tsai, Jo-Ting
• Format: Article
• Language: English
• Subjects: Animals; c-Myc protein; cancer recurrence; Cancer therapies; Carcinoma, Hepatocellular - genetics; Carcinoma, Hepatocellular - pathology; CD90 antigen; Cell adhesion & migration; Cell cycle; Cell differentiation; Cell Line, Tumor; Cell Proliferation - genetics; Cell Proliferation - physiology; Chemotherapy; Drug resistance; Gene Expression Regulation, Neoplastic - genetics; HCC-SCs; Hepatocellular carcinoma; Hepatocytes; Humans; Laboratory animals; LEF protein; Liver Neoplasms - genetics; Liver Neoplasms - pathology; LncRNA MALAT1; Medical research; Metastases; Metastasis; Mice; Molecular modelling; Myc protein; Neoplasm Recurrence, Local - genetics; Neoplasm Recurrence, Local - metabolism; Neoplastic Stem Cells - pathology; Non-coding RNA; Phenotypes; Polymerase chain reaction; Proteins; RNA, Long Noncoding - genetics; RNA, Long Noncoding - metabolism; Signal transduction; Stat3 protein; Stem cell transplantation; Stem cells; Therapeutic targets; tumorspheres; Vimentin; Wnt protein; Wnt Signaling Pathway - genetics; β-Catenin
• ISSN: 2073-4409; 2073-4409
• DOI: 10.3390/cells9041020

With recorded under-performance of current standard therapeutic strategies as highlighted by high rates of post-treatment (resection or local ablation) recurrence, resistance to chemotherapy, poor overall survival, and an increasing global incidence, hepatocellular carcinoma (HCC) constitutes a medical challenge. Accumulating evidence implicates the presence of HCC stem cells (HCC-SCs) in HCC development, drug-resistance, recurrence, and progression. Therefore, treatment strategies targeting both HCC-SCs and non-CSCs are essential. Recently, there has been an increasing suggestion of MALAT1 oncogenic activity in HCC; however, its role in HCC stemness remains unexplored. Herein, we investigated the probable role of MALAT1 in the SCs-like phenotype of HCC and explored likely molecular mechanisms by which MALAT1 modulates HCC-SCs-like and metastatic phenotypes. We showed that relative to normal, cirrhotic, or dysplastic liver conditions, MALAT1 was aberrantly expressed in HCC, similar to its overexpression in Huh7, Mahlavu, and SK-Hep1 HCC cells lines, compared to the normal liver cell line THLE-2. We also demonstrated a positive correlation between MALAT1 expression and poor cell differentiation status in HCC using RNAscope. Interestingly, we demonstrated that shRNA-mediated silencing of MALAT1 concomitantly downregulated the expression levels of β-catenin, Stat3, c-Myc, CK19, vimentin, and Twist1 proteins, inhibited HCC oncogenicity, and significantly suppressed the HCC-SCs-related dye-effluxing potential of HCC cells and reduced their ALDH-1 activity, partially due to inhibited MALAT1-β-catenin interaction. Additionally, using TOP/FOP (TCL/LEF-Firefly luciferase) Flash, RT-PCR, and western blot assays, we showed that silencing MALAT1 downregulates β-catenin expression, dysregulates the canonical Wnt signaling pathway, and consequently attenuates HCC tumorsphere formation efficiency, with concurrent reduction in CD133+ and CD90+ HCC cell population, and inhibits tumor growth in SK-Hep1-bearing mice. Taken together, our data indicate that MALAT1/Wnt is a targetable molecular candidate, and the therapeutic targeting of MALAT1/Wnt may constitute a novel promising anticancer strategy for HCC treatment.