Targeting ODC1 inhibits tumor growth through reduction of lipid metabolism in human hepatocellular carcinoma.

Ornithine decarboxylase 1 (ODC1), a metabolic enzyme critically involved in the polyamine biosynthesis, is commonly upregulated in hepatocellular carcinoma (HCC). Despite its altered expression in human HCC tissues, the molecular mechanism by which ODC1 alters the course of HCC progression and functions in HCC cell survival is unknown. Here we identified that silencing of ODC1 expression with small interfering (si) RNA causes inhibition of HCC cell growth through blockade of cell cycle progression and induction of apoptosis. Next, to obtain insights into the molecular changes in response to ODC1 knockdown, global changes in gene expression were examined using RNA sequencing. It revealed that 119 genes show same directional regulation (76 up- and 43 down-regulated) in both Huh1 and Huh7 cells and were considered as a common ODC1 knockdown signature. Particularly, we found through a network analysis that KLF2, which is known to inhibit PPARγ expression and adipogenesis, was commonly up-regulated. Subsequent Western blotting affirmed that the downregulation of ODC1 was accompanied by a decrease in the levels of PPARγ as well as of PARP-1, cyclin E1 and pro-caspase 9 delaying cell cycle progression and accelerating apoptotic signaling. Following the down-regulation of PPARγ expression, ODC1 silencing resulted in a strong inhibition in the expression of important regulators of glucose transport and lipid biogenesis, and caused a marked decrease in lipid droplet accumulation. In addition, ODC1 silencing significantly inhibited the growth of human HCC xenografts in nude mice. These findings indicate that the function of ODC1 is correlated with HCC lipogenesis and suggest that targeting ODC1 could be an attractive option for molecular therapy of HCC.

Knockdown of RPL9 expression inhibits colorectal carcinoma growth via the inactivation of Id-1/NF-κB signaling axis.

Ribosomal protein L9 (RPL9), a component of the 60S subunit for protein synthesis, is upregulated in human colorectal cancer. In the present study, we investigated whether RPL9 gained extraribosomal function during tumorigenesis and whether targeting of RPL9 with small interfering (si) RNA could alter the course of colorectal cancer progression. Our results showed that siRNA knockdown of RPL9 suppresses colorectal cancer (CRC) cell growth and long-term colony formation through an increase in sub-G1 cell population and a strong induction of apoptotic cell death. To obtain insights into the molecular changes in response to RPL9 knockdown, global changes in gene expression were examined using RNA sequencing. It revealed that RPL9-specific knockdown led to dysregulation of 918 genes in HCT116 and 3178 genes in HT29 cells. Among these, 296 genes showed same directional regulation (128 upregulated and 168 downregulated genes) and were considered as a common RPL9 knockdown signature. Particularly, we found through a network analysis that Id-1, which is functionally associated with activation of NF-κB and cell survival, was commonly downregulated. Subsequent western blot analysis affirmed that RPL9 silencing induced the decrease in the levels of Id-1 and phosphorylated IκBα in both HCT116 and HT29 cells. Also, the same condition decreased the levels of PARP-1 and pro-caspase-3, accelerating apoptosis. Furthermore, inhibition of RPL9 expression significantly suppressed the growth of human CRC xenografts in nude mice. These findings indicate that the function of RPL9 is correlated with Id-1/NF-κB signaling axis and suggest that targeting RPL9 could be an attractive option for molecular therapy of colorectal cancer.

Electro-hyperthermia up-regulates tumour suppressor Septin 4 to induce apoptotic cell death in hepatocellular carcinoma.

PURPOSE: Modulated electro-hyperthermia (mEHT) has been shown to be effective against various types of human tumours, including hepatocellular carcinoma (HCC). Here we aimed to investigate the molecular mechanism underlying the cytotoxic effects of mEHT to HCC cells. MATERIALS AND METHODS: Human liver cancer cell lines, Huh7 and HepG2, were treated with mEHT (42 °C/60 min) three times at 2-day intervals. Growth inhibition and apoptotic induction were evaluated using MTS, microscopic analysis, a clonogenic assay, annexin V/PI staining and a ccK18 ELISA. Global changes in gene expression were examined using RNA sequencing to obtain insights into molecular changes in response to mEHT. For in vivo evaluation of mEHT we used HepG2 HCC xenografts grown in nude mice. RESULTS: mEHT suppressed HCC cell proliferation and long-term colony formation through induction of apoptosis. The growth inhibitory effects are induced through a subset of molecular changes. Notably the expression level of septin 4 (SEPT4) (involved in pro-apoptotic activity and growth suppression) was up-regulated, whereas a key regulator of invasiveness G-Protein coupled receptor 64 (GPR64) was repressed. Subsequent Western blotting confirmed that the common increase in tumour suppressor SEPT4 in both Huh7 and HepG2 cells is accompanied by the restoration of cyclin-dependent kinase (CDK) inhibitor p21 and decrease in pro-caspase 7 and pro-caspase 3, thereby accelerating apoptotic signalling in HCC cells. Additionally, mEHT significantly inhibited the growth of human HCC xenografts in nude mice. CONCLUSIONS: These findings suggest that apoptotic cell death induced by mEHT is mediated by the up-regulation of tumour suppressor SEPT4 in human HCC cells.

Electro-hyperthermia inhibits glioma tumorigenicity through the induction of E2F1-mediated apoptosis.

PURPOSE: Modulated electro-hyperthermia (mEHT), also known as oncothermia, shows remarkable treatment efficacies for various types of tumours, including glioma. The aim of the present study was to investigate the molecular mechanism underlying phenotypic changes in oncothermic cancer cells. MATERIALS AND METHODS: U87-MG and A172 human glioma cells were exposed to mEHT (42 °C/60 min) three times with a 2-day interval and subsequently tested for growth inhibition using MTS, FACS and microscopic analysis. To obtain insights into the molecular changes in response to mEHT, global changes in gene expression were examined using RNA sequencing. For in vivo evaluation of mEHT, we used U87-MG glioma xenografts grown in nude mice. RESULTS: mEHT inhibited glioma cell growth through the strong induction of apoptosis. The transcriptomic analysis of differential gene expression under mEHT showed that the anti-proliferative effects were induced through a subset of molecular alterations, including the up-regulation of E2F1 and CPSF2 and the down-regulation of ADAR and PSAT1. Subsequent Western blotting revealed that mEHT increased the levels of E2F1 and p53 and decreased the level of PARP-1, accelerating apoptotic signalling in glioma cells. mEHT significantly suppressed the growth of human glioma xenografts in nude mice. We also observed that mEHT dramatically reduced the portion of CD133(+) glioma stem cell population and suppressed cancer cell migration and sphere formation. CONCLUSIONS: These findings suggest that mEHT suppresses glioma cell proliferation and mobility through the induction of E2F1-mediated apoptosis and might be an effective treatment for eradicating brain tumours.

Molecular Targeted Therapy for Hepatocellular Carcinoma: Present Status and Future Directions.

Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third most lethal neoplasm, causing an estimated 700000 deaths annually. Currently HCC has only one systemic molecular targeted therapy, the multi-kinase inhibitor, sorafenib. The standard-of-care for advanced liver cancer is limited because sorafenib can expand the median life expectancy of patients for only 1 year. Thus there is an urgent need to develop a novel molecular targeted therapy to improve therapeutic outcomes for HCC. HCCs are phenotypically and genetically heterogeneous tumors driven by diverse molecular mechanisms. However, HCCs exhibit certain common traits selected through genetic and epigenetic alterations. The identification of common molecular alterations may provide an opportunity to develop more effective anticancer treatment through targeted therapy. Recent studies in liver cancer biology have revealed a limited number of molecular targets responsible for initiating and maintaining dysregulated cell proliferation, including vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor (PDGFR), c-mesenchymal-epithelial transition factor-1 (c-Met), mammalian target of rapamycin (mTOR) and histone deacetylases (HDACs). New treatments involving inhibitors targeting several of these critical pathways are in development. This review describes the current understanding of target pathways, ongoing clinical trials using HCC-targeted agents, and future directions in the treatment of HCC.