How does hypoxia inducible factor-1α participate in enhancing the glycolysis activity in cervical cancer?

Abstract

The objective of this study is to explore the role of hypoxia inducible factor-1 (HIF-1) in glycolysis activity and its relationship with malignant biologic behaviors of cervical cancer. Immunohistochemistry was performed to study the protein expression and distribution of HIF-1α and glucose transport protein 1 (GLUT1) in cervical tissue of 158 cases, including 28 with normal cervical epithelium, 32 with cervical intraepithelial neoplasia, and 98 with invasive cervical cancer. Cobalt(II) chloride was used to induce hypoxia in Hela and Siha cells; the biologic behaviors of cells cultured in normal or hypoxic environments were monitored by colorimetric, Transwell, flow cytometry, and enzyme-linked immunosorbent assay; immunocytochemistry, Western blot, and reverse transcription-polymerase chain reaction were used to observe gene and protein expression of HIF-1α, GLUT1, and hexokinase II in cell lines during normoxia and hypoxia. The expression of HIF-1α and GLUT1 gradually increased from normal cervical tissue to cervical intraepithelial neoplasia, then to cervical cancer. There were significant differences among these groups (P < .05). HIF-1α was strongly associated with pathologic differentiation, clinic stage, magnitude of lesions, and patient age, whereas GLUT1 was associated with lymphatic metastasis (P < .05). HIF-1α was strongly associated with expression of GLUT1 (P < .05). In hypoxia, proliferation, invasion, resistance to apoptosis, and glycolysis of both Hela and Siha were enhanced compared with cells in normoxia (P < .05). Both gene and protein expressions of GLUT1 and hexokinase II were strengthened, whereas only the protein expression of HIF-1α was stronger in hypoxia than that in normoxia (P < .05). The results of Hela in normoxia and in hypoxia were similar to those of Siha (P > .05). HIF-1α plays a key role in cervical cancer both in vivo and in vitro. The role of HIF-1α can be implemented mainly by up-regulating its downstream gene, such as GLUT1, and the main mechanism may enhance glycolytic ability. Strong up-regulation and the role of HIF-1α suggest that HIF-1α could be an important factor in the onset and progression of cervical cancer and could be an attractive therapeutic molecular target for that type of cancer.