Xi-Lin Chen

Involvement of PI3K/PTEN/AKT/mTOR pathway in invasion and metastasis in hepatocellular carcinoma: Association with MMP‐9

Aim:  To investigate the status of Phosphatidylinositol 3‐kinase (PI3K)/PTEN/AKT/mammalian target of rapamycin (mTOR) pathway and its correlation with clinicopathological features and matrix metalloproteinase‐2, ‐9 (MMP‐2, 9) in human hepatocellular carcinoma (HCC).

Bead‐based microarray analysis of microRNA expression in hepatocellular carcinoma: miR‐338 is downregulated

Aim:  Recent studies have underlined causative links between microRNA (miRNA) deregulation and cancer development. However, the relevance of abnormally expressed miRNA to tumor biology has not been well understood in hepatocellular carcinoma (HCC).

Sonic hedgehog signaling pathway induces cell migration and invasion through focal adhesion kinase/AKT signaling-mediated activation of matrix metalloproteinase (MMP)-2 and MMP-9 in liver cancer

The aberrant activation of sonic hedgehog (SHH) pathway contributes to initiation and progression of various malignancies. However, the roles and underlying mechanisms of SHH signaling pathway in invasion and metastasis of liver cancer have not been well understood. In this study, we found that SHH signaling was activated and correlated with invasion and metastasis in hepatocellular carcinoma (HCC). Enhanced SHH signaling by recombinant human SHH N-terminal peptide (rSHH-N) promoted hepatoma cell adhesion, migration and invasion, whereas blockade of SHH signaling with SHH neutralizing antibody or cyclopamine suppressed hepatoma cell adhesion, migration and invasion. Furthermore, matrix metalloproteinase (MMP)-2 and MMP-9 expressions and activities were upregulated and downregulated by rSHH-N and SHH signaling inhibitor, respectively. The rSHH-N-mediated hepatoma cell migration and invasion was blocked by MMP-specific inhibitors or neutralizing antibodies to MMP-2 and MMP-9. In addition, phosphorylations of AKT and focal adhesion kinase (FAK) were increased and decreased by rSHH-N and SHH signaling inhibitor, respectively. Further investigations showed that activation of AKT and FAK were required for rSHH-N-mediated upregulation of MMP-2 and MMP-9, cell migration and invasion. Finally, we found that SHH protein expression was positively correlated with phosphorylatd FAK Tyr397, phosphorylatd AKT Ser473, MMP-2 and MMP-9 protein expressions in HCC samples. Taken together, our findings suggest that SHH pathway induces cell migration and invasion through FAK/AKT signaling-mediated MMP-2 and MMP-9 production and activation in liver cancer.

miR-338-3p suppresses invasion of liver cancer cell by targeting smoothened†

MicroRNAs are involved in human carcinogenesis and cancer progression. Our previous study has shown that loss of miR‐338‐3p expression is associated with clinical aggressiveness of hepatocellular carcinoma (HCC). However, the exact roles and mechanisms of miR‐338‐3p remain unknown in HCC. To determine whether and how miR‐338‐3p influences liver cancer cell invasion, we studied miR‐338‐3p in the liver cancer cell lines, and we found that miR‐338‐3p is down‐regulated in treated cells. Forced expression of miR‐338‐3p in SK‐HEP‐1 cells suppressed cell migration and invasion, whereas inhibition of miR‐338‐3p in SMMC‐7721 cells induced cell migration and invasion. Furthermore, smoothened (SMO) was identified as a direct target of miR‐338‐3p. Forced expression of miR‐338‐3p down‐regulated SMO and matrix metalloproteinase (MMP)‐9 expression, but inhibition of miR‐338‐3p up‐regulated SMO and MMP9 expression. However, small interfering RNA targeted SMO reversed the effects induced by blockade of miR‐338‐3p. SMO and MMP9 were overexpressed and associated with invasion and metastasis in HCC tissues. These data indicate that miR‐338‐3p suppresses cell invasion by targeting the smoothened gene in liver cancer in vitro and miR‐338‐3p might be a novel potential strategy for liver cancer treatment. Copyright

FAK is involved in invasion and metastasis of hepatocellular carcinoma

Studies have shown that focal adhesion kinase (FAK) is overexpressed in several human tumors and plays an important role in tumor progression. However, the role and underlying mechanisms of FAK in hepatocellular carcinoma (HCC) progression remains to be elucidated. In this study, we examined FAK and phosphorylated FAK Tyr397 expression in a large series of HCCs. We found that both FAK and phosphorylated FAK Tyr397 were overexpressed in HCC samples and HCC cell lines. Increased FAK and phosphorylated FAK Tyr397 expressions were correlated with tumor stage, vascular invasion and intrahepatic metastasis in HCC. Furthermore, HCC cell adhesion, migration and invasion were substantially impaired by siRNA-mediated knockdown of FAK expression, whereas cell growth, apoptosis and cell cycle distribution were not affected. In addition, depletion of FAK induced a significant reduction in expressions and activities of both MMP-2 and MMP-9. Taken together, FAK contributes to invasion and metastasis of HCC partly through regulating expressions and activations of both MMP-2 and MMP-9, suggesting FAK could be a promising therapeutic target for HCC.

Clinical significance of miR-221 and its inverse correlation with p27Kip1 in hepatocellular carcinoma

The aim of the present study is to explore possible role of miR-221 in the pathogenesis of HCC. Matched HCC and adjacent non-cancerous samples were assayed for the expression of miR-221 and three G1/S transition inhibitors: p27Kip1, p21WAF1/Cip1and TGF-β1 by in situ hybridization and immunohistochemistry respectively. p27Kip1 is one of miR-221’s proven targets. Real time qRT-PCR was used to investigate miR-221 and p27Kip1 transcripts in different clinical stages. Western blotting was used to analyze the expression levels of p27Kip1 protein in different clinical stages. In result, miR-221 and TGF-β1 are frequently up-regulated in HCC, while p27Kip1 and p21WAF1/Cip1 proteins are frequently down-regulated. Moreover, miR-221 and p27Kip1’s expression correlated with metastasis and miR-221’s expression also correlated with tumor size. Both of p21WAF1/Cip1and TGF-β1’s expression correlated with tumor differentiations. miR-221’s upregulation and p27Kip1’s downregulation were significantly associated with tumor stages and metastasis. In conclusion, miR-221 is important in tumorigenesis of HCC, possibly by specifically down-regulating p27Kip1, a cell-cycle inhibitor. These results indicate miR-221 as a new therapeutic target in HCC.

Upregulation of PTEN involved in rosiglitazone-induced apoptosis in human hepatocellular carcinoma cells.

AbstractAim:To investigate the effects of rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, on the expression of the phosphatase and tensin homologue deleted on chromosome 10 gene (PTEN) and cell growth in hepatocellular carcinoma cells, as well as the underlying mechanisms of these effects.Methods:RT-PCR and Western blotting analyses were performed to detect transcription and the expression of PTEN in Hep3B cells treated with rosiglitazone. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was used to evaluate cell growth. Flow cytometry, DNA fragmentation analysis, caspase enzymatic assay, and Hoechst 33258 staining were used to determine cell apoptosis. Furthermore, small interfering RNA was used to suppress PTEN expression.Results:Rosiglitazone increased the expression of PTEN in a dose-and time-dependent manner through the PPARγ-dependent signal transduction pathway. PTEN upregulation was concomitant with a decreased level of Akt phosphorylation, subsequently resulting in cell growth inhibition and apoptosis in Hep3B cells. PTEN knockdown dramatically blocked these effects of rosiglitazone. Moreover, the exposure of cells to rosiglitazone activated caspases-9 and -3 during apoptotic proceeding.Conclusion:Thus, upregulation of PTEN is involved in the inhibition of cell growth and the induction of cell apoptosis by rosiglitazone, suggesting that rosiglitazone may be useful in liver cancer therapy via apoptosis.

Downregulation of LncRNAH19 and MiR-675 promotes migration and invasion of human hepatocellular carcinoma cells through AKT/GSK-3β/Cdc25A signaling pathway

SummaryLncRNAH19 has been implicated as having both oncogenic and tumor suppression properties in cancer. LncRNAH19 transcripts also serve as a precursor for miR-675. However, it is unknown whether LncRNAH19 and miR-675 are involved in the migration and invasion of hepatocellular carcinoma (HCC) cells. The purpose of this study was to investigate the effect and mechanism of LncRNAH19 and miR-675 on migration and invasion of HCC cells. The migration and invasion of HCC cells were measured by Transwell migration and invasion assays after transfection of HCC cells with miR-675 inhibitors and LncRNAH19siRNA. The levels of LncRNAH19 and miR-675 were detected by quantitative reverse transcriptase real-time polymerase chain reaction (qRT-PCR), and the protein expression of AKT, GSK-3β and Cdc25A by Western blotting analysis. The expression levels of LncRNAH19 and miR-675 were higher in MHCC-97H cells than in L02, Huh-7 and HepG2 cells. Transwell migration assay revealed that the miR-675 inhibitor and LncRNAH19siRNA could significantly increase the migration of HCC cells (P<0.01) as compared with the control group. Transwell invasion assay demonstrated that the miR-675 inhibitor and LncRNAH19siRNA could significantly increase the invasion of HCC cells (P<0.01) as compared with the control group. Western blotting analysis showed that the expression levels of AKT and Cdc25A were significantly increased (P<0.05), and the expression level of GSK-3β was significantly decreased (P<0.05) after treatment with miR-675 inhibitors and LncRNAH19siRNA as compared with the control group. These findings suggested that inhibition of LncRNAH19 and miR-675 expression can promote migration and invasion of HCC cells via AKT/GSK-3β/Cdc25A signaling pathway.LncRNAH19 has been implicated as having both oncogenic and tumor suppression properties in cancer. LncRNAH19 transcripts also serve as a precursor for miR-675. However, it is unknown whether LncRNAH19 and miR-675 are involved in the migration and invasion of hepatocellular carcinoma (HCC) cells. The purpose of this study was to investigate the effect and mechanism of LncRNAH19 and miR-675 on migration and invasion of HCC cells. The migration and invasion of HCC cells were measured by Transwell migration and invasion assays after transfection of HCC cells with miR-675 inhibitors and LncRNAH19siRNA. The levels of LncRNAH19 and miR-675 were detected by quantitative reverse transcriptase real-time polymerase chain reaction (qRT-PCR), and the protein expression of AKT, GSK-3β and Cdc25A by Western blotting analysis. The expression levels of LncRNAH19 and miR-675 were higher in MHCC-97H cells than in L02, Huh-7 and HepG2 cells. Transwell migration assay revealed that the miR-675 inhibitor and LncRNAH19siRNA could significantly increase the migration of HCC cells (P<0.01) as compared with the control group. Transwell invasion assay demonstrated that the miR-675 inhibitor and LncRNAH19siRNA could significantly increase the invasion of HCC cells (P<0.01) as compared with the control group. Western blotting analysis showed that the expression levels of AKT and Cdc25A were significantly increased (P<0.05), and the expression level of GSK-3β was significantly decreased (P<0.05) after treatment with miR-675 inhibitors and LncRNAH19siRNA as compared with the control group. These findings suggested that inhibition of LncRNAH19 and miR-675 expression can promote migration and invasion of HCC cells via AKT/GSK-3β/Cdc25A signaling pathway.

Down-regulation of Gli-1 inhibits hepatocellular carcinoma cell migration and invasion

Glioma-associated oncogene homolog-1 (Gli-1) is considered a marker of Hedgehog pathway activation and is associated with the progression of several cancers. We have previously reported that Gli-1 was correlated with invasion and metastasis in hepatocellular carcinoma (HCC). However, the exact roles and mechanisms of Gli-1 in HCC invasion are unclear. In this study, we found that small interfering RNA mediated down-regulation of Gli-1 expression significantly suppressed adhesion, motility, migration, and invasion of both SMMC-7721 and SK-Hep1 cells. Furthermore, down-regulation of Gli-1 significantly reduced expressions and activities of both matrix metalloproteinase (MMP)-2 and MMP-9. In addition, we found that down-regulation of Gli-1 resulted in up-regulation of E-cadherin and concomitant down-regulation of Snail and Vimentin, consistent with inhibition of epithelial-mesenchymal transition (EMT). Taken together, our results suggest that down-regulation of Gli-1 suppresses HCC cell migration and invasion likely through inhibiting expressions and activations of MMP-2, 9 and blocking EMT.

Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-fluorouracil antitumor activity through activation of the PPARγ signaling pathway

AbstractAim:Resistance to 5-fluorouracil (5-FU) is a major cause of chemotherapy failure in advanced hepatocellular carcinoma (HCC).Rosiglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, has a crucial role in growth inhibition and induction of apoptosis in several carcinoma cell lines. In this study, we examine rosiglitazone-induced sensitization of HCC cell lines (BEL-7402 and Huh-7 cells) to 5-FU.Methods:The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate cell viability. Western blotting analysis was performed to detect the protein expression (PPARγ, PTEN, and COX-2) in BEL-7402 cells. Immunohistochemistry staining was used to examine the expression of PTEN in 100 advanced HCC tissues and paracancerous tissues. In addition, small interfering RNA was used to suppress PPARγ, PTEN, and COX-2 expression.Results:Rosiglitazone facilitates the anti-tumor effect of 5-FU in HCC cell lines, which is mediated by the PPARγ signaling pathway. Activation of PPARγ by rosiglitazone increases PTEN expression and decreases COX-2 expression. Since distribution of PTEN in HCC tissues is significantly decreased compared with the paracancerous tissue, over-expression of PTEN by rosiglitazone enhances 5-FU-inhibited cell growth of HCC. Moreover, down-regulation of COX-2 is implicated in the synergistic effect of 5-FU.Conclusion:Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-FU antitumor activity through the activation of PPARγ. The results suggest potential novel therapies for the treatment of advanced liver cancer.