Silencing of heparanase by siRNA inhibits tumor metastasis and angiogenesis of human breast cancer in vitro and in vivo.

Expression of the heparanase gene is associated with invasive, angiogenic and metastatic potential of diverse malignant tumors and cell lines. Here we used RNA interference strategies to evaluate the role of human heparanase in breast malignancy and to explore the therapeutic potential of its specific targeting. The siRNA targeting human heparanase almost completely inhibited the expression of heparanase in human breast carcinoma MDA-MB-435 cells, whereas the mismatched siRNA showed no effect. Cells transfected with heparanase siRNA expressed significantly less heparanase and profoundly reduced invasion and adhesion in vitro. In MDA-MB-435 cell xenograft model, tumors treated with siRNA were less vascularized and less metastatic than those treated with saline and the mismatched controls. The association of reduced levels of heparanase and altered tumorigenic properties in cells with anti-heparanase siRNA indicates that heparanase is important in cancer progress and has potential use as a target for anticancer drug development.

Growth arrest induced by C75, A fatty acid synthase inhibitor, was partially modulated by p38 MAPK but not by p53 in human hepatocellular carcinoma.

C75, a well-known fatty acid synthase (FAS) inhibitor, has been shown to possess potent anti-cancer activity in vitro and in vivo. In this study, we reveal that C75 is a cell cycle arrest inducer and explore the potential mechanisms for this effect in hepatocellular carcinoma (HCC) cell lines with abundant FAS expression: HepG2 and SMMC7721 cells with wt-p53, and Hep3B cells with null p53. The results showed FAS protein expression and basal activity levels were higher in HepG2 cells than in the other two HCC cell lines. Treatment with C75 inhibited FAS activity within 30 min of administration and induced G(2) phase arrest accompanied by p53 overexpression in HepG2 and SMMC7721 cells. By contrast, C75 triggered G(1) phase arrest in Hep3B cells, and RNA interference targeting p53 did not attenuate C75-induced G(2) arrest in HepG2 cells. Similarly, p53 overexpression via p53 plasmid transfection did not affect C75-induced G(1) phase arrest in Hep3B cells. However, we observed a clear correlation between p38 MAPK activation triggered by C75 and the induction of cell cycle arrest in all three HCC cells. Furthermore, treatment with the p38 MAPK inhibitor SB203580 reduced p38 MAPK activity and cell cycle arrest, and also partially restored cyclin A, cyclin B1, cyclin D1 and p21 protein levels. Collectively, it was p38 MAPK but not p53 involved in C75-mediated tumor cell growth arrest in HCC cells.

[Fatty acid synthase: specific target for cancer therapy].

Fatty acids, the products of fatty acid synthesis, are essential components and forms of energy for cancer growth. Compared to normal human tissues, many common human cancers express elevated levels of fatty acid synthase (FAS), the important enzyme responsible for the synthesis of fatty acid, suggesting FAS can be a specific target for cancer therapy.

Identification of genes responsive to apoptosis in HL-60 cells.

AIM: To identify genes responsive to apoptosis in HL-60 cells treated by homoharringtonine. METHODS: cDNA microarray technology was used to detect gene expression and the result of microarrays for genes (TIEG and VDUP1) was confirmed by Northern analysis. RESULTS: Seventy-five individual mRNAs whose mass changed significantly were identified. Among these genes (25 were up-regulated and 50 were down-regulated), most are known related to oncogenes and tumor suppressor. Some genes were involved in apoptosis signaling pathways. CONCLUSION: TGF beta and TNF apoptosis signaling pathways were initiated during apoptosis in HL-60 cells. TIEG and VDUP1 play important roles in mediating apoptosis.

IGF-I increases IGFBP-5 and collagen alpha1(I) mRNAs by the MAPK pathway in rat intestinal smooth muscle cells.

IGF-I is a potent fibrogenic growth factor that stimulates proliferation of intestinal smooth muscle cells and increases synthesis of collagen and IGF-I-binding proteins by the cells. These processes contribute to intestinal fibrosis that develops in patients with Crohn's disease and in Lewis-strain rats with experimental Crohn's disease. The aim of this study was to determine which early docking proteins are associated with IGF-I receptor signal transduction and which transduction pathway is involved in IGF-I-mediated gene regulation in intestinal smooth muscle cells. Primary cultures of smooth muscle cells isolated from the muscularis externa of the distal colon of Lewis rats were treated with IGF-I (100 ng/ml). Immunoprecipitation studies demonstrated that IGF-I stimulation resulted in tyrosine phosphorylation of IRS-1, IRS-2, and Shc. Coimmunoprecipitation demonstrated a close association between the IGF-I receptor and these three early docking proteins. Concurrent treatment with the MAPK inhibitor PD98059 (10 microM) resulted in an inhibition of the IGF-I-mediated increase in IGFBP-5 and collagen alpha(1)(I) mRNAs, while concurrent treatment with the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin (100 nM) had no effect. In additional experiments, cells were transiently transfected with adenoviral vectors dominantly expressing inactive mutant Akt or constitutively expressing wild-type Akt. In both cases, the IGF-I-mediated increase in collagen I protein did not differ from that observed in control cultures that had been transfected with an adenoviral vector carrying the LacZ reporter gene. These results suggest that the MAPK pathway is key to IGF-I-mediated gene regulation in intestinal smooth muscle cells, whereas data do not suggest a role for the Akt-dependent pathway in our system.