Clinicopathologic significance of hypoxia-inducible factor 1alpha overexpression in gastric carcinomas.
ABSTRACT Hypoxia-inducible factor 1alpha (HIF-1alpha) plays a key role in responses to hypoxia and expression of HIF-1alpha downstream genes leads to both an adapted metabolism and increased oxygen supply. We investigated the clinical significance of HIF-1alpha expression in gastric carcinoma.
We examined HIF-1alpha, vascular endothelial growth factor (VEGF), and insulin-like growth factor-2 (IGF-2) expression patterns immunohistochemically in 126 specimens of gastric carcinoma. CD34 antigen levels were also examined by immunohistochemistry to determine microvessel density (MVD) within tumors and correlations between HIF-1alpha expression, clinicopathological features, and survival were examined.
HIF-1alpha expression correlated with tumor size (P<0.005), depth of invasion (P=0.018), VEGF expression (P=0.03), and intra-tumor MVD (P<0.005). IGF-2 expression was more prevalent in HIF-1alpha positive than in HIF-1alpha negative tumors and the 5-year survival rate was 58.4% for HIF-1alpha positive patients and 81.5% for HIF-1alpha negative patients (P=0.009). HIF-1alpha expression is an independent prognostic factor in gastric carcinoma (P=0.032).
Overexpression of HIF-1alpha in gastric carcinomas may upregulate its downstream gene products leading to VEGF-mediated angiogenesis, and resulting in a poor prognosis for patients.
Article: Up-regulation of hypoxia inducible factor-1α by cobalt chloride correlates with proliferation and apoptosis in PC-2 cells.[show abstract] [hide abstract]
ABSTRACT: The exact mechanism of the effects of hypoxia on the proliferation and apoptosis in carcinoma cells is still conflicting. This study investigated the variation of hypoxia-inducible factor-1α(HIF-1α) expression and the apoptosis effect of hypoxia stimulated by cobalt chloride (CoCl(2)) in pancreatic cancer PC-2 cells. PC-2 cells were cultured with different concentration (50-200 μmol/L) of CoCl(2) after 24-120 hours to simulate hypoxia in vitro. The proliferation of PC-2 cells was examined by MTT assay. The cellular morphology of PC-2 cells were observed by light inverted microscope and transmission electron microscope(EM). The expression of HIF-1α on mRNA and protein level was measured by semi-quantitative RT-PCR and Western blot analysis. Apoptosis of PC-2 cells were demonstrated by flow cytometry with Annexin V-FITC/PI double staining. MTT assay showed that the proliferation of PC-2 cells were stimulated in the first 72 h, while after treated over 72 h, a dose- dependent inhibition of cell growth could be observed. By using transmission electron microscope, swollen chondrosomes, accumulated chromatin under the nuclear membrane and apoptosis bodies were observed. Flow cytometer(FCM) analysis showed the apoptosis rate was correlated with the dosage of CoCl(2). RT-PCR and Western blot analysis indicated that hypoxia could up-regulate the expression of HIF-1α on both mRNA and protein levels. Hypoxic microenvironment stimulated by CoCl(2) could effectively induce apoptosis and influence cell proliferation in PC-2 cells, the mechanism could be related to up-expression of HIF-1α.Journal of Experimental & Clinical Cancer Research 03/2012; 31:28. · 2.15 Impact Factor
Article: Everolimus (RAD001) and anti-angiogenic cyclophosphamide show long-term control of gastric cancer growth in vivo.[show abstract] [hide abstract]
ABSTRACT: Metronomic dosing of cytotoxic drugs such as cyclophosphamide has shown anti-angiogenic activity, most likely by inducing hypoxia in tumors. Hypoxia leads to activation of escape mechanisms allowing tumor cell survival. This potentially limits the activity of anti-angiogenic strategies. We hypothesized that mTORC1 inhibition by everolimus (RAD001) leads to suppression of HIF-1alpha and VEGF resulting in synergistic anti-tumor activity in combination with anti-angiogenically dosed cyclophosphamide. In vitro, effects of everolimus on mTORC1 signaling, proliferation, cell cycle, HIF-1alpha expression and VEGF secretion were evaluated in two gastric cancer cell lines. In vivo, anti-tumor activity of everolimus in combination with metronomic cyclophosphamide was studied in a NCI-N87 human gastric cancer SCID mouse xenograft model. Expression of Ki-67 and HIF-1alpha, activated caspase 3, microvascular density (MVD) and tumor necrotic area assessed. Everolimus decreased proliferation and attenuated production of HIF-1alpha as well as VEGF in gastric cancer cells in vitro. In vivo, everolimus significantly inhibited tumor growth. This anti-tumor activity was linked to a significant increase in tumor necrotic area (p < 0.02) and trends for decreased proliferation, increased apoptosis, decreased HIF-1alpha and lower tumor MVD (p = n.s.). The combination of everolimus and cyclophosphamide resulted in a striking and highly significant long-term tumor growth control compared to monotherapy (p < 0.001), which was associated with a sharp increase in central tumor necrosis (p < 0.001). In conclusion, the combination of everolimus and metronomic cyclophosphamide showed synergistic anti-tumor activity. Depriving cancer cells by everolimus of factors necessary for their survival under hypoxia induced by anti-angiogenic chemotherapy appears to be a promising approach for treatment of gastric cancer.Cancer biology & therapy 06/2008; 7(9):1377-85. · 2.64 Impact Factor
Article: Growth suppression of cervical carcinoma by pigment epithelium-derived factor via anti-angiogenesis.[show abstract] [hide abstract]
ABSTRACT: Pigment epithelium-derived factor (PEDF), an angiogenesis inhibitor with multiple other functions, balances angiogenesis in the eye and blocks tumor progression. Cervical cancer, an angiogenesis-dependent tumor, is the second most common cancer in women without effective treatment. It has been reported that PEDF can inhibit several types of tumors, however, the potential of PEDF for the treatment of cervical carcinoma has not been well explored. The present study was designed to investigate the effect of recombinant PEDF on the neovascularization and growth of cervical carcinoma. We found for the first time that PEDF was downregulated apparently in human cervical carcinoma nests compared to either normal cervical epithelium or nonneoplastic peritumoral epithelium, suggesting potential anti-angiogenesis function by supplement of PEDF in cervical carcinoma. Intraperitoneal injection of PEDF in xenografted cervical carcinoma mice suppressed tumor growth with 68% reduction. Microvessel density in tumor tissues treated with PEDF was significantly decreased. PEDF dose-dependently inhibited proliferation and induced apoptosis of endothelial cells, but had no direct effect on proliferation and apoptosis of Hela cells under both normoxia and hypoxia. These results suggested that PEDF suppressed tumor growth by blocking angiogenesis instead of a direct cytotoxic effect on tumor cells. VEGF, a major angiogenic stimulator, was downregulated by PEDF in Hela cells by downregulation of HIF-1α, a crucial transcriptional factor for VEGF expression. Downregulation of VEGF expression in tumor cells through inhibiting HIF-1α, thus attenuating the paracrine effect of VEGF on endothelial cells, may represent a mechanism for the anti-angiogenic activity of PEDF.Cancer biology & therapy 06/2010; 9(12):967-74. · 2.64 Impact Factor