Abstract 2024: Over-expression of miR-106b in metastatic hepatocellular carcinoma using an orthotopic metastasis animal model

Abstract

Abstract Hepatocellular carcinoma (HCC) is one the most fatal cancers worldwide. Early diagnosis is crucial for curing the disease. However, patients are often diagnosis at late-stage with distant metastasis, and the prognosis of metastatic HCC is poor. Molecular pathological studies confirm that gene expression alteration plays a critical role in disease progression. Recently it has been discovered that microRNA (miRNA) can alter the gene expression at post-transcription level. This study aimed to elucidate the role of miRNA in development of metastatic HCC using an orthotopic animal model and the molecular pathway involved. Orthotopic metastasis animal model was established by implanting HCC cell lines onto the liver of the SCID mice. Tumor growth was monitored by in vivo imaging system. Primary tumor and lung metastasis were observed after 12 weeks of inoculation. Tumor were then excised and established into primary tumor cell lines (PT) and lung metastatic cell lines (LM). Functional studies comparing the PT and LM cell lines derived from HCC cell line PLC demonstrated higher cell invasion and migration ability in the metastatic cell line compared with the primary tumor cell line. In addition, the LM cell line possessed more stress fiber than the PT cell line. The PLC-derived cell lines and another metastatic HCC cell line, MHCC97H-derived cell lines were subjected to the miRNA microarray analysis. Fifteen human miRNAs were found to be differentially expressed in the LM cell lines when compared to the PT cell lines. miR-106b was one of the miRNAs which was over-expressed in LM cell lines. We further confirmed our findings in HCC clinical sample and found that miR-106b was over-expressed in HCC tumor compared with the adjacent non-tumor tissue, and its expression was significantly associated with the tumor grade (p=0.018). MicroRNA knock-down study was performed by using the miR-106b LNA knock-down probe. The miR-106b knock-down reverted the cell migration phenotype, and fluorescent staining of stress fiber formation showed that the miR-106b knock-down cells have less stress fiber formation than the parental cell lines and the scramble control. We further studied the expression of E-cadherin in PLC-PT, PLC-LM, the scramble control and the miR-106b knock-down cell lines. Our result demonstrated that miR-106b expression inversely correlated with E-cadherin level. Since decrease of E-cadherin expression is the hallmark for epithelia-mesenchymal transition (EMT), further studies will focus on the role of miR-106b in EMT of HCC cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2024.