Restoring miR122 in human stem-like hepatocarcinoma cells, prompts tumor dormancy through Smad-independent TGF-β pathway

Abstract

miR122 is the prevalent miRNA in adult healthy liver and it is responsible for liver stem cell differentiation towards hepatocyte lineage. Its expression is frequently lost in hepatocellular carcinoma (HCC). We studied the effects of restoring miR122 expression in a distinctive cell line derived from human HCC-BCLC9 cells-with a solid stem-like cell profile, high tumor initiating ability and undetectable miR122 expression. We generated a stable BCLC9 cell line that expresses miR122 (BCLC9-miR122). Restitution of miR122 in BCLC9 cells, decreases cell proliferation rate and reduces significantly tumor size in vivo. BCLC9-miR122 cells down-regulate expression of MYC, KLF4, FOXM1, AKT2 and AKT3 genes and up-regulate FOXO1 and FOXO3A gene expression. In addition, miR122 transfected cells decreased AKT2 kinase activation while decreased FOXO1 and FOXO3A protein inactivation. Reduction in tumor size in BCLC9-miR122 associated with an increase in p38MAPK protein expression and activation leading to a low phospho-ERK1/2 to phospho-p38 ratio. Treatment of miR122 positive cells with an inhibitor of TGFBR1 activation, abolished tumor dormancy program and recovered cell proliferation rate through a Smad-independent TGF-β response.HCC stem-like cells can be directed towards cell differentiation and tumor dormancy by restoring miR122 expression. We demonstrate, for the first time, that dormancy program is achieved through a Smad-independent TGF-β pathway. Reestablishing miR122 expression is a promising therapeutic strategy that would work concurrently reducing tumor aggressiveness and decreasing disease recurrence.

Antiapoptotic BCL-2 proteins determine sorafenib/regorafenib resistance and BH3-mimetic efficacy in hepatocellular carcinoma

“…To verify these observations we used the anchor-free growing human hepatocellular carcinoma cells. BCLC9 cells, established from a well-differentiated human HCC, exhibit a stem cell phenotype and are highly efficient tumor initiating cells in nude mice [ 28 ]. Mimicking the results obtained in mice bearing HepG2 tumors, ABT-263 was highly effective reducing the growth of BCLC9 tumors treated with sorafenib (Figure 7A ).…”

Biomarkers Associated With Response to Regorafenib in Patients With Hepatocellular Carcinoma

“…Most of the miRNAs have not been described previously in HCC pathogenesis, with the exception of MIR122 and MIR200. [22][23][24][25] For example, MIR122 targets IGF1R, PDK4, LDHA, and GALNT10, thereby regulating RAS/RAF/ERK signaling and glycolysis, and has been reported to overcome resistance to sorafenib. 23 Interestingly, our functional analysis suggests that response to regorafenib is associated with previously described HCC molecular subtypes, with an improvement in response to regorafenib in the Hoshida S3 subgroup.…”

The Diverse Mechanisms of miRNAs and lncRNAs in the Maintenance of Liver Cancer Stem Cells

“…TGF- β is an antimitogenic cytokine that becomes oncogenic in advanced tumors [ 66 ]. The restoration of miR-122 has been reported to be able to induce a dormant state of stem-like HCC through the Smad-independent TGF- β pathway [ 67 ].…”