Hepatitis C Virus Proteins Modulate MicroRNA Expression and Chemosensitivity in Malignant Hepatocytes

Abstract

Purpose: Hepatocellular cancer (HCC) is highly resistant to chemotherapy and is associated with poor prognosis. Chronic hepatitis C virus (HCV) infection is a major cause of HCC. However, the effect of viral proteins in mediating chemosensitivity in tumor cells is unknown. We postulated that HCV viral proteins could modulate therapeutic responses by altering host cell microRNA (miRNA) expression.Experimental Design: HepG2 malignant hepatocytes were stably transfected with full-length HCV genome (Hep-394) or an empty vector (Hep-SWX). MiRNA profiling was done by using a custom microarray, and the expression of selected miRNAs was validated by real-time PCR. Protein expression was assessed by Western blotting, whereas caspase activation was assessed by a luminometric assay.Results: The IC 50 to sorafenib was lower in Hep-394 compared with Hep-SWX control cells. Alterations in miRNA expression occurred with 10 miRNAs downregulated >2-fold and 23 miRNAs upregulated >2-fold in Hep-394 cells compared with controls. Of these, miR-193b was overexpressed by 5-fold in Hep-394 cells. miR-193b was predicted to target Mcl-1, an antiapoptotic protein that can modulate the response to sorafenib. The expression of Mcl-1 was decreased, and basal caspase-3/7 activity and poly ADP ribose polymerase cleavage were increased in Hep-394 cells compared with controls. Moreover, transfection with precursors to miR-193b decreased both Mcl-1 expression and the IC 50 to sorafenib.Conclusions: Cellular expression of full-length HCV increases sensitivity to sorafenib by the miRNAdependent modulation of Mcl-1 and apoptosis. Modulation of miRNA responses may be a useful strategy to enhance response to chemotherapy in HCC. Clin Cancer Res; 16(3); 957-66. ©2010 AACR.

miR-193b Regulates Mcl-1 in Melanoma

“…38 Note that an earlier study showed that miR-193b targets Mcl-1 in malignant hepatocyte cells via the matched seed sequence that was essential for posttranscriptional repression. 39 Three scenarios could explain this discrepancy. First, the present study analyzes the interaction between miR-193b and the full length Mcl-1 3= UTR, whereas Braconi et al 39 examined a short fragment of the Mcl-1 3= UTR that included the seed pairing site.…”

“…39 Three scenarios could explain this discrepancy. First, the present study analyzes the interaction between miR-193b and the full length Mcl-1 3= UTR, whereas Braconi et al 39 examined a short fragment of the Mcl-1 3= UTR that included the seed pairing site. Thus, the seedless miR-193b binding site in the Mcl-1 3= UTR could have been missing from the fragment studied by the Braconi group.…”

Role of microRNAs in solid tumors

“…The expression of microRNA is also reported to be associated with HBV and HCV infections 52,53 which are closely related to HCC, and the association with hepatocarcinogenesis has been indicated. 54 Reduced expression of miR-122 in a chimpanzee model of HCV hepatitis/HCC was reported to result in successful control of HCC,55 and the clinical application to humans is greatly anticipated.…”

Erratum to: Negative feedback of miR-29 family TET1 involves in hepatocellular cancer

“…A growing body of evidence has demonstrated that miRNAs have played important roles in cancer development and clinical outcomes of cancer patients [11]. Up to date, different study cohorts find that miRNAs are involved in HCC development and some of them have been identified to correlate with prognosis or accepted to be potential therapeutic targets [12][13][14][15]. For example, the study by Jiang and his colleagues revealed that miR-199a, miR-21 and miR-301 were differentially expressed between tumor and adjacent benign liver.…”

“…Furthermore, several deregulated miRNAs (e.g., miR-21, miR-101, miR-195, miR-122, miR-221, miR-223 and miR-224) have been shown to regulate cell growth, apoptosis, migration or invasion [17][18][19][20][21][22]. In conclusion, the ability of miRNAs to function as tumor promoters or suppressors in hepatocarcinogenesis has led to new insights into the molecular pathways involved in HCC [14,23]. To date, several oncogenes, caused by apoptosis-related molecules, such as T cell leukemia/lymphoma 1 (TCL1), myeloid cell leukemia sequence 1 (Mcl-1), cell division cycle 42 (CDC42) and phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), have been characterized as targets of the miR family [24][25][26][27][28][29].…”