Abstract 4686: MicroRNA mir-93 activates oncogenic c-Met/PI3K/Akt pathway targeting PTEN in hepatocellular carcinoma
Authors: Ohta Katsuya , Hoshino Hiromitsu , Hata Keisuke , Wang Jinhua , Huang Sharon , Menon Vijay , Colquhoun Steven , Hoon Dave S. B. 
Published: May 2015

Background; The incidence rate of hepatocellular cellular carcinoma (HCC) has been rapidly increasing globally; however, no effective systemic therapy has been established for advanced HCC after first line therapy with Sorafenib fails. Combining the immediate need for more effective therapy and emerging reports on epigenetic events in HCC, we aimed to identify specific micro RNA (miR) regulating oncogenic pathways in HCC to serve as potential therapeutic targets.

Materials and Methods; We performed initial screening by miR array analysis in 6 HCC cell lines, as well as stage I-IV HCC paraffin-embedded archival tissue (PEAT) specimens (n=47) which were compared to normal livers and liver cirrhosis specimens (n=74). IHC staining analysis of c-Met and miRs expression by qRT-PCR were performed using cell lines and PEAT specimens. The effect on miR levels on recombinant HGF treatment of HCC cells was assessed. We performed functional miR assays by luciferase-vectors with 3′ untranslated sequences (3′UTR) targeted to specific miR binding regions transfected to HCC cells. c-Met/PI3K/Akt pathway analysis was examined using qRT-PCR and western blot analysis. Biological functional activities of miR in HCC were assessed using proliferation, migration, invasion, and 3D sphered colony assays. Chemosensitivity of HCC kinase inhibitors, Sorafenib and Tivantinib on HCC cell lines were examined using a cell viability assay.

Results; We identified that miR-93 was expressed over 10-fold in HCC cell lines compared to normal liver cells via screening by miR array analysis. miR-93 expression was significantly upregulated in HCC PEAT specimens compared to normal and cirrhosis liver specimens (p=0.002). miR-93 expression was shown to have a significant correlation with IHC staining of c-Met protein in HCC PEAT. In vitro studies demonstrated that the HCC cells treated with recombinant HGF (50 μM; 24 hr) induced overexpression of miR-93. Focusing on miR-93 target genes, miR-93 was demonstrated to interfere with the PTEN expression through binding of specific 3′ UTR regions. miR-93 oncogenic effects were shown to regulate phosphorylation of Akt by suppressing PTEN. We demonstrated that miR-93 was silencing tumor-related pathway genes, whereby its function is controlling c-Met/PI3K/Akt signal transduction. It was confirmed that inhibiting miR-93 expression (anti-miR) would suppress proliferation, migration, and invasion of HCC cells. Anti-miR treatment of HCC cell lines significantly enhanced chemosensitivity against kinase inhibitors, Sorafenib (p=0.021) and Tivantinib (p&lt;0.001).

Conclusion: Our results indicated that miR-93 is targeting PTEN involved in tumorigenesis of HCC through the oncogenic c-Met/PI3K/Akt pathway. We demonstrated that anti-miR-93 enhances chemosensitivity against Sorafenib and Tivantinib in HCC. miR-93 is a potential therapeutic target to mitigate chemosensitivity to kinase inhibitors in HCC.

Note: This abstract was not presented at the meeting.

Citation Format: Katsuya Ohta, Hiromitsu Hoshino, Keisuke Hata, Jinhua Wang, Sharon Huang, Vijay Menon, Steven Colquhoun, Dave S. B. Hoon. MicroRNA mir-93 activates oncogenic c-Met/PI3K/Akt pathway targeting PTEN in hepatocellular carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4686. doi:10.1158/1538-7445.AM2014-4686