Hypoxic microenvironment always exists in solid tumors, and it closely relates to the development and metastasis of solid tumor. As a main transcription factor responding to hypoxic environment, hypoxia-inducible factor (HIF) can promote tumor cell proliferation, survival, angiogenesis, and epithelial-mesenchymal transition (EMT), etc. EMT is a biological process that epithelial phenotype was transformed into mesenchymal phenotype, which is mainly associated with its signaling pathways, transcription factors, inflammatory factors and miRNAs, and plays a vital role in tumor invasion and metastasis. This paper summarizes the effects of hypoxia signaling pathway, Wnt/β-catenin signaling pathway, Notch signaling pathway, NF-κB signaling pathway, Hedgehog (Hh) signaling pathway and PI3K/Akt signaling pathway on the EMT of tumor cells.
Objective To explore the effect and mechanism of rapamycin and deferoxamin on wound healing after ischemia and hypoxia. Methods The model of ischemia and hypoxia wound was made on the back of 40 SPF male adult Sprague Dawley rats, weight (300±20) g; they were randomly divided into 4 groups (n=10): the control group (group A), deferoxamine intervention group (group B), rapamycin intervention group (group C), and deferoxamine+rapamycin intervention group (group D). At 3, 6, and 9 days after model preparation, rats of groups A, B, C, and D were intra-peritoneally injected with normal saline, deferoxamin (10 mg/kg), rapamycin (3 mg/kg), deferoxamin (10 mg/kg)+rapamycin (3 mg/kg) respectively. The wound healing was observed and the healing time was recorded in each group; the wound healing tissue was harvested to test the mRNA and protein expressions of mammalian target of rapamycin (mTOR), hypoxia inducible factor 1α (HIF-1α), and vascular endothelial growth factor (VEGF) by real-time fluorescence quantitative PCR and Western blot at 2 days after wound healing. Results All rats survived to the end of the experiment, and wounds healed; the healing time of groups A, B, and D was significantly shorter than that of group C (P<0.05), but there was no significant difference between groups A, B, and D (P>0.05). Real-time fluorescence quantitative PCR showed that the expression of mTOR mRNA in groups C and D was significantly decreased when compared with the expressions in groups A and B (P<0.05); there was significant difference between groups A and B (P<0.05), but no significant difference between groups C and D (P>0.05). The expressions of HIF-1α mRNA and VEGF mRNA were signi-ficantly higher in groups B and D than groups A and C, and in group A than group C (P<0.05), but there was no signifi-cant difference between groups B and D (P>0.05). Western blot showed that the relative expressions of mTOR protein in groups C and D were significantly decreased when compared with the expressions in groups A and B (P<0.05), but there was no significant difference between groups C and D (P>0.05). The relative expressions of HIF-1α protein in groups A, B, and C were significantly increased when compared with expression in group D (P<0.05), but there was no significant difference between groups A, B, and C (P>0.05). The relative expression of VEGF protein were significantly lower in groups B, C, and D than group A, in group D than groups B and C, and in group C than group B (P<0.05). Conclusion Defe-roxamin can promote the wound healing of rats after ischemia and hypoxia, and the effect of rapamycin is opposite. It may be related to the existence of mTOR and HIF-1 signaling pathway in chronic ischemia-hypoxia wound.
Objective To explore the influence on the expressions of vascular endothelial growth factor (VEGF) gene and matrix metalloproteinase-2 (MMP-2) gene in hepatocellular carcinoma of SMMC-7721 cells with RNA interference (RNAi) silencing the expression of hypoxia inducible factor-1α (HIF-1α) gene. Methods Firstly, constructed short hairpin RNA (shRNA) targeting for HIF-1α gene, and then transfected it to SMMC-7721 cells after combining with plasmid. The SMMC-7721 cells were divided into three groups, silencing group, negative control group, and blank control group, which were transfected with HIF-1α-shRNA-pGenesil-1 recombinant vector, shRNA-HK-pGenesil-1 recombinant vector, and pGenesil-1 vector respectively. Transfection cells were screened by the concentration of 500 μg/mL G418, and then positive and negative cell clones with transfection recombination carrier were obtained. Detected the expressions of HIF-1α mRNA, VEGF mRNA, and MMP-2 mRNA in the 3 groups with real time PCR (RT-PCR) technology, under the condition of hypoxic training 6 h, 12 h, and 24 h, as well as conventional oxygen training. Results There was no expression of HIF-1α mRNA at conventional oxygen condition in the 3 groups, and there was no significant difference in expressions of VEGF mRNA and MMP-2 mRNA among the 3 groups (P>0.05) at the condition of conventional oxygen training. The expressions of HIF-1α mRNA, VEGF mRNA, and MMP-2 mRNA in the silencing group, compared with the the negative control group and the blank control group, were obviously decreased (P<0.05) under the condition of hypoxic training (6, 12, and 24 h), while there was no significant difference between the negative control group and the blank control group at each time point (P>0.05), but the expressions of HIF-1α mRNA, VEGF mRNA, and MMP-2 mRNA in the 3 groups under every condition of hypoxic training were all higher than those of conventional oxygen condition (P<0.05). Under the condition of hypoxic training, the expressions of HIF-1α mRNA, VEGF mRNA, and MMP-2 mRNA in the 3 groups decreased over time, and there was significant difference between any 2 time points in each group (P<0.05). Conclusion RNAi technique can effectively silence the expression of HIF-1α mRNA of SMMC-7721 cells, and then silence the expressions of VEGF and MMP-2 mRNA, to inhibit the invasion and metastasis of hepatocellular carcinoma.
ObjectiveTo explore the effects of hypoxia inducible factor-1 alpha (HIF-1α) on the reverse differentiation of hepatocellular carcinoma cells into liver cancer stem cells, and the maintenance of malignant biological behavior in hypoxic environment.MethodsCD133-negative cells in HepG2 cells were separated by immunomagnetic beads and divided into two groups. The cells of siRNA group were transfected with siRNA-HIF-1α to silence the expression of HIF-1α gene, while cells of the blank control group did not transfect any siRNA fragments. The two groups of cells were cultured under normal and hypoxic conditions respectively. MTT, cloning and Transwell chamber experiments were used to detect the proliferation and invasion ability of cells. Western blot and real-time PCR (RT-PCR) were used to detect the expressions of HIF-1α, CD133, CD90, and CD44 protein and mRNA in cells.ResultsMTT results showed that the cell proliferation rate increased with the prolongation of hypoxia in four groups. Compared with the blank control group at 24, 32, 40, and 48 hours, the cell proliferation rate decreased significantly after siRNA-HIF-1a transfection, on both two kinds of cultured conditions (P<0.05). The results of plate cloning experiment showed that the number of cell-forming clones increased significantly after hypoxic culture (there were significant differences between the transfected normoxic group and transfected hypoxic group, blank control normoxic group and blank control hypoxic group, P<0.05); and the formation of transfected hypoxic condition group at the same time of hypoxia was also significant (P<0.05). The number of clones were significantly less than that of the blank control group at the hypoxic condition (P<0.05). Transwell lab experiment showed that after hypoxic culture, the number of cells migrated to the inferior chamber in the transfection group was significantly reduced compared with that of the blank control group (P<0.05). Western blot and RT-PCR results showed that the expression levels of HIF-1α protein and tumor stem cell markers (CD133, CD90, and CD44 protein) in the blank control hypoxic condition group were significantly higher than those in the other three groups (P<0.05); after siRNA-HIF-1a transfection, HIF-1α mRNA and tumor stem cell markers mRNA (CD133, CD90, and CD44 mRNA) in the transfected hypoxic condition group were significantly lower than those in the transfected normal condition group and the blank control normal condition group (P<0.05).ConclusionsIn hypoxia environment, HIF-1α can promote hepatocellular carcinoma cells to differentiate into liver cancer stem cells and enhance their malignant biological behavior.
ObjectiveTo investigate the expression and correlation of hypoxia inducible factor 1α (HIF-1α) and autophagy related molecules (Beclin1 and LC3B) in rat nucleus pulposus cells under hypoxia in vitro.MethodsThe nucleus pulposus cells were extracted from the nucleus pulposus of healthy adult Sprague Dawley rats and passaged. The 3rd generation cells were identified by HE staining and collagenase type Ⅱ immunofluorescence staining and randomly divided into 4 groups. The cells in group A were cultured for 8 hours under normal oxygen condition (37℃, 5%CO2, 20%O2); the cells in group B were cultured for 8 hours under hypoxia condition (37℃, 5%CO2, 1%O2); the cells in group C were transfected with HIF-1α-small interfering RNA and cultured for 8 hours under hypoxia condition; and the cells in group D were cultured with autophagy inhibitor 3-MA for 8 hours under hypoxia condition. Western blot and real-time fluorescence quantitative PCR (qRT-PCR) were used to detect the expressions of HIF-1α and autophagy related molecules (Beclin1 and LC3B) in all groups.ResultsHE staining of the 3rd generation nucleus pulposus cells showed that the cytoplasm was light pink and the nucleus was blue black, and the collagenase type Ⅱ immunofluorescence staining was positive. Western blot and qRT-PCR results showed that the relative expressions of HIF-1α, Beclin1, and LC3B proteins and genes in group B were significantly higher than those in group A (P<0.05); the relative expressions of HIF-1α, Beclin1, and LC3B proteins and genes in group C were significantly lower than those in group B (P<0.05). There was no significant difference in the relative expression of HIF-1α protein and gene between groups B and D (P>0.05); while the relative expressions of Beclin1 and LC3B proteins and genes in group D were significant lower than those in group B (P<0.05).ConclusionHypoxia can induce the expressions of HIF-1α and autophagy related molecules (Beclin1 and LC3B) in rat nucleus pulposus cells, and HIF-1α in rat nucleus pulposus cells under hypoxia is related to the expression of autophagy related molecules, that is, down-regulation of HIF-1α can significantly reduce the expression of autophagy related molecules, while the down-regulation of autophagy levels under hypoxia has no or little effect on the expression of HIF-1α.
ObjectiveTo investigate the effects of hypoxia inducible factor 1α (HIF-1α) overexpression on the differentiation of stem cells derived from human exfoliated deciduous teeth (SHED) into vascular endothelial cells.MethodsSHED was isolated from the retained primary teeth donated by healthy children by using collagenase digestion method. The third generation cells were identified by flow cytometry and alizarin red and alkaline phosphatase (ALP) staining after osteogenic differentiation culture. The SHED were divided into blank control group (SHED without any treatment), empty group (SHED infected with empty lentivirus), HIF-1α overexpression group (SHED infected with HIF-1α overexpression lentivirus), Wnt inhibitor group (SHED interfered by IWR-1), and combination group (HIF-1α overexpressed SHED interfered by IWR-1). Real-time fluorescence quantitative PCR (qRT-PCR) and Western blot were used to analyze the expressions of HIF-1α mRNA and protein in the SHED of blank control group, empty group, and HIF-1α overexpression group. Then the SHED in 5 groups were induced differentiation into vascular endothelial cells for 14 days. The expressions of cell surface marker molecule [von Willebrand factor (vWF) and CD31] were detected by flow cytometry. The mRNA expressions of vascular cell adhesion protein 1 (VCAM-1), KDR (Kinase-inserted domain containing receptor), and VE-cadherin (VE) were analyzed by qRT-PCR. The protein expressions of phosphate-glycogen synthasc kinase 3β (p-GSK3β) and β-catenin were analyzed by Western blot. The tube forming ability of induced cells was detected by Matrigel tube forming experiment. The ability of endothelial cells to phagocytic lipid after differentiation was detected by DiI-labeled acetylated low density lipoprotein (DiI-Ac-LDL) phagocytosis.ResultsAfter identification, the cells were SHED. After lentivirus transfection, compared with the blank control group and the empty group, the expressions of HIF-1α mRNA and protein in the HIF-1α overexpression group increased significantly (P<0.05). Compared with the blank control group and the empty group, the expressions of VCAM-1, KDR, and VE mRNA, the percentages of vWF positive cells and CD31 positive cells, and the relative expression of β-catenin protein were significantly higher (P<0.05), the relative expression of p-GSK3β protein was significantly lower (P<0.05), the number of tubules formed and the ability to phagocytic lipids significantly increased (P<0.05) in the HIF-1α overexpression group; while the indicators in the Wnt inhibitor group were opposite to those in the HIF-1α overexpression group (P<0.05). Compared with the HIF-1α overexpression group, the expressions of VCAM-1, KDR, and VE mRNA, the percentages of vWF positive cells and CD31 positive cells, and the relative expression of β-catenin protein were significantly lower (P<0.05), the relative expression of p-GSK3β protein was significantly higher, and the number of tubules formed and the ability of phagocytosis of lipids significantly reduced, showing significant differences between groups (P<0.05).ConclusionOverexpression of HIF-1α can promote SHED to differentiate into vascular endothelial cells by activating Wnt/β-catenin signaling pathway.
ObjectiveTo investigate the correlations among the cadual homeobox gene 2 (CDX2), hypoxia inducible factor-1α (HIF-1α) protein expressions, and tumor budding in the colorectal cancer (CRC). MethodsIn this study, 63 CRC specimens surgically removed in the First Affiliated Hospital of Xi’an Jiaotong University from January 2012 to September 2015 were collected. The CDX2 and HIF-1α protein expressions were detected by immunohistochemical staining streptavidin-biotin peroxidase two-step method. The staining and the grade of tumor budding were observed under an optical microscope, and the correlation was analyzed using Spearman test. ResultsThe positive expressions of CDX2 and HIF-1α proteins in the CRC tissues were 35 (55.6%) and 47 (74.6%) cases, respectively, which was a negative correlation in the CRC (rs=–0.302, P=0.017). The positive expressions of CDX2 and HIF-1α proteins in the tumor budding of colorectal cancer were 21 (51.2%) and 26 (63.4%) cases, respectively, which was also a negative correlation in the tumor budding of CRC (rs=–0.336, P=0.031), but there was no statistic correlation between the grade of tumor budding and CDX2 or HIF-1α positive protein expression in the CRC (rs=0.113, P=0.370; rs=–0.026, P=0.838). ConclusionsThe positive expression between CDX2 and HIF-1α has a negative correlation in the same CRC specimen and which has a negative correlation in tumor budding. There is no statistic correlation between grade of tumor budding and CDX2 or HIF-1α protein expression in the CRC. Hypoxia environment may be involved in the downregulation of CDX2 level during the malignant progression of CRC.