Osteopontin promotes ovarian cancer progression and cell survival and increases HIF-1alpha expression through the PI3-K/Akt pathway.

Osteopontin (OPN) is a secreted, integrin-binding matrix phosphorylated glycoprotein that is overexpressed in many advanced cancers. However, the functional mechanisms by which OPN contributes to the development of ovarian cancer are poorly understood. Here, we reveal that acquired expression of OPN by HO-8910 ovarian cancer cells greatly promoted the progression of ovarian cancer. OPN expression dramatically increased the colony formation of ovarian cancer cells in vitro and tumor growth in vivo. Under the stress induced by serum depletion or curcumin treatment, OPN expression promoted the survival of ovarian cells through preventing stress-induced apoptosis. At the molecular level, both endogenous and exogenous OPN expression activated the PI3-K/Akt survival pathway and dramatically decreased p53 expression under serum depletion. In addition, HIF-1alpha was induced in OPN-producing cells under normoxia. Furthermore, we also found that inhibition of the PI3-K/Akt pathway attenuated OPN-mediated HIF-1alpha up-regulation in ovarian cancer cells. Taken together, these results indicate that OPN can increase the survival of ovarian cancer cells under stress conditions in vitro and promote the late progression of ovarian cancer in vivo, and the survival-promoting functions of OPN are mediated through Akt activation and the induction of HIF-1alpha expression.

Abnormal expression, highly efficient detection and novel truncations of midkine in human tumors, cancers and cell lines.

We detected aberrant Midkine (MK) expressions in human insulinoma and pancreatic cancer tissues by immunohistochemistry, revealing its potential role in tumorigenesis/carcinogenesis. With a nested-touchdown PCR program we were able to detect the tMK in all human tumor/cancer tissues and cancer/tumor cell lines. Detection of MK in the peripheral cells and precancerous lesions implies its potential for early cancer/tumor diagnosis. Furthermore, we have discovered two novel truncations of the MK, tMKB and tMKC, respectively, in the disease specimens. Our data not only provide an efficient methodology potentially for clinical application but also shed light on the molecular mechanism underlying the role for MK in tumorigenesis/carcinogenesis.

Effects of tachyplesin on proliferation and differentiation of human hepatocellular carcinoma SMMC-7721 cells.

AIM: To investigate the antitumor activities of tachyplesin on human hepatocellular carcinoma (HCC) cells. METHODS: Tachyplesin, isolated from acid extracts of Chinese horseshoe crab (Tachypleus tridentatus) hemocytes, was used to treat the human HCC cell line SMMC-7721. Effects of tachyplesin on the proliferation of SMMC-7721 cells were measured with trypan blue dye exclusion test and HE staining. The morphology and ultrastructure of the cells were examined by light microscopy and transmission electron microscopy, respectively. The activities of gamma-glutamyltransferase (gamma-GT) and tyrosine aminotransferase (TAT) were assayed with biochemical methods. The levels of alpha fetoprotein (alpha-FP), proliferating cell nuclear antigen (PCNA), p21( WAF1/CIP1) and c-myc were examined by immunocytochemistry. RESULTS: After treatment with tachyplesin 3.0 mg/L, the proliferation of SMMC-7721 cells was inhibited significantly, with the cell growth inhibitory rate amounted to 55.57 % and the maximum cell mitotic index declined by 43.68 %. The morphology and ultrastructure underwent restorational alteration. The activity of gamma-GT declined while TAT activity increased obviously, and the levels of alpha-FP and PCNA decreased. Moreover, the expression of p21(WAF1/CIP1) protein was up-regulated and that of c-myc protein was down-regulated. CONCLUSION: Tachyplesin could effectively inhibit the proliferation of hepatocarcinoma cells, reverse the malignant morphological and ultrastructural characteristics, alter the levels of enzymes and antigens, regulate the expression of differentiation-associated oncogene and tumor suppressor gene, and induce hepatocarcinama cell differentiation.

Growth arrest and apoptosis of human hepatocellular carcinoma cells induced by hexamethylene bisacetamide.

AIM: To investigate the cellular effects of hybrid polar compound hexamethylene bisacetamide (HMBA) on the growth and apoptosis of human hepatocellular carcinoma cells and to provide the molecular mechanism for potential application of HMBA in the treatment of liver cancer. METHODS: Effects of HMBA on the growth of human hepatocellular carcinoma SMMC-7721 cells were assayed by MTT chronometry. Apoptosis induced by HMBA was detected by phase-contrast microscopy, flow cytometry, propidium iodide staining and immunocytochemical analysis. RESULTS: The growth of SMMC-7721 cells was significantly inhibited by HMBA, and the growth inhibitory rate was 51.1%, 62.6%, 68.7% and 73.9% respectively after treatment with 5.0, 7.5, 10.0 and 12.5 mmol/L of HMBA. In the cells treated with 10 mmol/L of HMBA for 72 h, the population of cells at sub-G(1) phase significantly increased, and the apoptotic bodies and condensed nuclei were detected. Moreover, treatment of SMMC-7721 cells with 10 mmol/L of HMBA down-regulated the expression of Bcl-2 anti-apoptotic protein, while slightly up-regulated the level of pro-apoptotic protein Bax. CONCLUSION: Treatment with 10.0 mmol/L of HMBA can significantly inhibit the growth and induce apoptosis of human hepatocellular carcinoma SMMC-7721 cells by decreasing the ratio of Bcl-2 to Bax.

Anti-proliferation and apoptosis induced by a novel intestinal metabolite of ginseng saponin in human hepatocellular carcinoma cells.

20-O-(beta-D-glucopyranosyl)-20(S)-protopanaxadiol (IH-901), a novel intestinal bacterial metabolite of ginseng protopanaxadiol saponins, is reported to induce apoptosis in a variety of cancer cells. We purified the compound and measured its in vitro anti-tumor activity. IH-901 inhibited cell growth of human hepatocellular carcinoma SMMC7721 cells in a dose- and time-dependent manner. We also found that IH-901 induced apoptotic cell death concurrent with cell cycle arrest in G0-G1 phase in SMMC7721 cells. At the molecular level, we show that IH-901 upregulates cytochrome c, p53, and Bax expression, and downregulates pro-caspase-3 and pro-caspase-9 expressions in a dose-dependent manner, while the levels of Bcl-2 and Bcl-X(L) were unchanged in IH-901-treated SMMC7721 cells. These results provide significant insight into the anticarcinogenic action of IH-901.

[Effects of HMBA on the expression of cell-cycle-associated genes in human hepatocarcinoma SMMC-7721 cells].

In this study, the effects of HMBA on the expression of G0/G1 phase arrest-associated genes in human hepatocarcinoma SMMC-7721 cells were investigated. Immunocytochemistry and in situ hybridization assay revealed that the levels of p21WAF1/CIP1 and p16 proteins and the level of p21WAF1/CIP1 mRNA were increased while the levels of CDK4 and Cyclin D1 proteins and c-myc mRNA were decreased in the cells treated with HMBA. These results showed that HMBA could up-regulate the expression of p21WAF1/CIP1 and p16 genes, down-regulate the activity of Cyclin D1-CDK4 and the transcription of c-myc gene which were necessary for cells entering into S phase, and so arrest the cells in G0/G1 phase, and induce the differentiation of human hepatocarcinoma SMMC-7721 cells.

[Tachyplesin-induced differentiation of human hepatocarcinoma cell line SMMC-7721].

BACKGROUND & OBJECTIVE: The study on antitumor activities of marine bioactive substances is an important field in exploiting marine bioactive substances and antitumor drugs. And the induction of tumor cell differentiation is a new strategy for drug therapy of tumors. So the authors used tachyplesin, a marine bioactive substance, to investigate its effects on the differentiation of human hepatocarcinoma SMMC-7721 cells for further studying its antitumor activities and mechanisms. METHODS: Tachyplesin, which was isolated from hemocytes of horseshoe crab (Tachypleus tridentatus), was used to treat human hepatocarcinoma SMMC-7721 cells. Light microscopy and transmission electron microscopy were applied to examine the changes in morphology and ultrastructure of SMMC-7721 cells, respectively. The activities of alkaline phosphatase or the expression of AFP and PCNA were assessed by cytochemistry or immunocytochemistry. RESULTS: In the cells treated with 3.0 micrograms/ml tachyplesin, the morphology and ultrastructure returned to be normal, the activity of alkaline phosphatase was decreased and the levels of AFP and PCNA were downregulated. CONCLUSION: Tachyplesin might effectively reverse the malignant morphology and ultrastructure, change the activity of enzyme and the levels of antigens associated with hepatocarcinoma cell, and induce the differentiation of the human hepatocarcinoma SMMC-7721 cells.