微缺氧对人结肠癌细胞HT-29骨桥蛋白及核转录因子表达及其侵袭能力的影响

Moderate hypoxia up-regulates the expression of osteopontin and NF-κB and augments invasive capacity in colon carcinoma cell line HT-29

目的探讨微缺氧与人结肠癌细胞HT-29侵袭能力的关系及其机制。方法建立微缺氧模型,噻唑蓝(MTT)比色试验测定HT-29细胞的异质性黏附能力,transwell侵袭试验判定其侵袭游走能力,内皮细胞小管形成实验检测促进新生血管形成的能力;将HT-29细胞微缺氧处理0、6、12、24、48 h,明胶酶谱分析检测分泌的MMP-2/9活性变化,逆转录-聚合酶链反应(RT-PCR)和Western blot检测骨桥蛋白(OPN)的mRNA和蛋白表达,Western blot检测胞核内核转录因子(NF-κB/p65)蛋白表达。结果微缺氧诱导24 h后,HT-29细胞的异质性黏附能力、侵袭游走能力显著增加,明显促进人脐静脉内皮细胞(HUVECs)形成管状结构。微缺氧下6 h,MMP-2/9活性无明显变化,尔后随着微缺氧时间的延长,其活性逐渐显著上调,24 h达顶峰,48与24 h差异无统计学意义(P>0.05)。HT-29细胞在微缺氧的诱导下,其OPN的mRNA和蛋白以及胞核内NF-κB/p65蛋白的表达趋势与MMP-2/9活性变化趋势类同。结论微缺氧能诱导HT-29细胞异质性黏附能力、侵袭游走能力显著增加,MMP-2/9活性上调,促进新生血管形成而促使其向恶性表型转化。OPN- NF-κB可能是微缺氧下继HIF-I之外的另一重要调节途径,该途径与微缺氧诱导的恶性表型密切相关。

Objective To investigate the correlation between moderate hypoxia and invasive capacity in colon carcinoma cell line HT-29 and explore its latent mechanism of malignant transformation. Methods Hypoxie conditions were produced referring to the PO2 of tumor in vivo. The beterotypie adhesiveness of HT-29 cells was detected by MTT assay; Reaction to a hypoxic environment was determined via invasion across a matrigel-coated transwell filter;Tube formation of human umbilical vein endothelial cells （HUVECs） was adopted to evaluate the ability of tumor angiogenesis in vitro. After 0,6,12,24 or 48 h of hypoxia, MMP-2/9 activity was assessed by gelatin zymography, and osteopontin mRNA and protein levels detected by RT-PCR and Western blot respectively. NF-KB/p65 levels in nucleus were measured by Western blot after extraction of nucleic protein. Results After induction by moderate hypoxia for 24 h, the beterotypie adhesiveness and invasive capacity of HT-29 cells were significantly enhanced. HT-29 cells significantly promoted HUVECs to form tube structure. MMP-2/9 activity under moderate hypoxia at 6 h showed no significant change as compared with that under normal conditions. Thereafter, gradually, it was significantly up-regulated with the extending of hypoxia time and reached the peak at 24 h. The trend of osteopontin mRNA and protein and NF-KB/p65 protein in nucleus was similar to that of MMP-2/9 under moderate hypoxia. Conclusion Moderate hypoxia could induce HT-29 cells to malignant transformation through enhancing beterotypic adheslveness,invasive capacity and tumor angiogenesis and up-regtdation of MMP-2/9 activity. OPN- NF-KB may be an important modulatory pathway besides HIF-1 under hypoxie condltlon,which was involved in malignant phenotype induced by moderate hypoxia.