Mechanism of anti-tumor effect of HIF-1alpha silencing on cervical cancer in nude mice

Abstract

To observe the anti-tumor effect of silencing the expression of HIF-1alpha on cervical cancer in nude mice and to explore its mechanism of action. Human cervical cancer cell line Siha cells were divided into 3 groups: mock control group, control group transfected with scrambled sequence plasmid, and experimental group transfected with pU-HIF-1alpha-shRNA eukaryotic expression plasmid. Cultured cells of the three groups were inoculated in nude mice to establish cervical cancer-bearing nude mice. HIF-1alpha RNAi assay was performed to evaluate the tumor-suppressive effect of HIF-1alpha silencing on cervical cancer-bearing nude mice. Immunohistochemistry and Western blot were used to observe the distribution and protein expression of HIF-1alpha and GLUT1, while RT-PCR was adopted to detect the gene expression of HIF-1alpha, GLUT1 and HKII. The product of glycolysis (lactic acid) and apoptosis in tumor cells were detected by colorimetry and semi-quantitative TUNEL staining, respectively. The tumor growth in experimental group was significantly slower than that in the two control groups (P < 0.05). On the 50th day after transplantation, the tumor weight in the experimental group was (1.90 +/- 0.28) g, significantly lower than (2.95 +/- 0.77) g in the control group and (2.54 +/- 0.56) g in the mock group (P < 0.01). In the experimental group, the gene and protein levels of HIF-1alpha were 0.45 +/- 0.04 and 1.25 +/- 0.92, and the levels of GLUT1 were 0.32 +/- 0.02 and 1.25 +/- 0.48, respectively. Both indicators in HIF-1alpha and GLUT1 were lower than that in the two control groups (P < 0.05). The expression levels of HKII gene and lactic acid in the experimental group were lower than that in the two control groups (P < 0.05), but the apoptotic cells were much more numerous in the experimental group than that in matched control groups (P < 0.01). The gene therapy by siRNA targeted silencing of HIF-1alpha may down-regulate its downstream genes GLUT1 and HKII expression, therefore, to reduce the tumor glycolysis activity and promote tumor cell apoptosis, and exert a tumor-suppressing effect in vivo.