MiR-222 Overexpression Confers Cell Migratory Advantages in Hepatocellular Carcinoma through Enhancing AKT Signaling

Abstract

Purpose: This study aims to profile the expressions of 156 microRNAs (miRNA) in hepatocellular carcinoma (HCC) and to characterize the functions of miR-222, the most significantly upregulated candidate identified.Experimental Design: miRNA expression profile in HCC tumors, matching adjacent cirrhotic livers, and cell lines was conducted using quantitative PCR. Common miR-222 upregulations were further validated in a larger cohort of tumors. The functional effects of miR-222 inhibition on HCC cell lines were examined. The downstream modulated pathways and target of miR-222 were investigated by coupling gene expression profiling and pathway analysis, and by in silico prediction, respectively. Luciferase reporter assay was done to confirm target interaction.Results: We identified a 40-miRNA signature that could discriminate tumors from adjacent cirrhotic liver tissue, and further corroborated common miR-222 overexpression in tumors relative to its premalignant counterpart (55.3%; P < 0.0001). Increased miR-222 expression correlated significantly with advanced stage HCC and with the shorter disease-free survival of patients (P ≤ 0.01). Inhibition of miR-222 in Hep3B and HKCI-9 significantly retarded cell motility (P < 0.05). Further investigations suggested that AKT signaling was the major pathway influenced by miR-222. A consistent reduction of AKT phosphorylation in Hep3B and HKCI-9 was shown following miR-222 suppression. The protein phosphatase 2A subunit B (PPP2R2A) was predicted as a putative miR-222 target in silico. We found that miR-222 inhibition could augment the tumor protein level and restore luciferase activity in reporter construct containing the PPP2R2A 3′ untranslated region (P = 0.0066).Conclusions: Our study showed that miR-222 overexpression is common in HCC and could confer metastatic potentials in HCC cells, possibly through activating AKT signaling. Clin Cancer Res; 16(3); 867-75.

PBX3 is targeted by multiple miRNAs and is essential for liver tumour-initiating cells

“…Paradoxically, miR-222 was previously regarded as oncogene in some reports because it could enhance some tumour cell growth by targeting CDK inhibitor p27 in vitro, and was found to be upregulated in HCC and some other types of cancers 42,51,52 ; however, its tumourpromoting role was rarely validated in vivo. Our data support miR-222 to be a tumour suppressor in HCC by controlling the stemness and tumorigenicity of a2d1 þ TICs, further confirming that the roles of miRNAs are cell context-dependent 50 .…”

“…Since the downregulation of let-7c and miR-200b and the upregulation of miR-222 were found extensively in HCC cells [40][41][42] , the fact that most HCC cells remain a2d1-negative led us to propose that miR-222 could rescue the effects of let-7c/miR-200b down-regulation on the expression of PBX3 and a2d1 in HCC cells. To test this hypothesis, we overexpressed miR-222 in Huh7 cells with let-7c and miR-200b knocked down simultaneously by respective Tud RNAs.…”

HepatomiRNoma: The proposal of a new network of targets for diagnosis, prognosis and therapy in hepatocellular carcinoma

“…This effect confers a metastatic potential in cancer cells as demonstrated by Wong et al (2010). Yang et al (2014b) suggested that MiR-222 overexpression promotes proliferation of human HCC cells by downregulating the p27 expression at post-transcriptional level.…”

MicroRNAs in the Occurrence and Development of Primary Hepatocellular Carcinoma

“…A recent discovery of PTEN is that microRNA-221 and microRNA-222 directly target genes involved in TRAIL resistance and increase the mobility of HCC [27]. In addition to the PTEN gene, microRNA-221 and microRNA-222 can also directly regulate protein phosphates' 2A subunit B (PPP2R2A) and tumor suppression factor TIMP3 expression, thereby activating the Akt signaling pathway and metal epitope peptide to promote the invasion and metastasis of HCC [28]. A report also shows a new microRNA (microRNA-143) mediated nuclear factor kb (NF-κB), promotes hepatitis B virus-related hepatocellular carcinoma metastasis [29].…”