Hypoxia-to-reoxygenation condition as one of the internal carcinogenic factors of common cancers

我们研究了在一系列缺血再灌注条件下产生的自由基是否可以作为正常或癌前细胞的内源性致癌因子。我们从人上皮细胞、啮齿类动物永生化成纤维细胞和良性纤维肉瘤细胞中获得了各种细胞系，以检查这些细胞系在一系列缺氧-复氧条件下培养后是否可以转化为致瘤细胞。缺氧-复氧条件下培养的细胞产生自由基。以2 ′，7 ′-二氯二氢荧光素二乙酸酯（H_2DCFDA）为特异性探针，检测自由基中的过氧化物。过氧化物的产生被抑制的几个自由基清除剂添加到培养基中。在这些细胞系中，非致瘤性小鼠成纤维细胞系在裸鼠中转化为致瘤性细胞系。然后，我们将它们的基因/蛋白质表达与正常对应物进行了比较。我们通过DNA微阵列和双向蛋白电泳的联合分析，筛选出了两个可能与肿瘤发生相关的基因。与亲本细胞相比，这两个基因在致瘤细胞中的表达降低。我们发现，这两个基因中的一个实际上调节小鼠成纤维细胞的致瘤潜力。我们希望在检测这些基因在各种人类肿瘤组织和啮齿动物自发产生的肿瘤中的表达后进一步证实这一发现。

We examined whether free radicals generated in a series of ischemia-reperfusion condition could act as an endogenous carcinogenic factor in normal or premalignant cells. We obtained various cell lines from human epithelial cells, rodent immortalized fibroblasts and benign fibrosarcoma cells to examine whether those cell lines could be converted into tumorigenic ones after cultivation in a series of hypoxia-reoxygenation condition. Free radicals were produced in the cells after they were cultured in the hypoxia-reoxygenation condition. Peroxides, a part of free radicals, were detected by using the specific probe 2', 7'-dichlorodihydrofluorescein diacetate (H2DCFDA). The production of peroxides was suppressed by an addition of several free radical scavengers into the culture medium. Among those cell lines, non-tumorigenic mouse fibroblast cell lines were converted into tumorigenic ones in nude mice. We then compared their gene/protein expressions with their normal counterparts. We have identified two genes possibly related with carcinogenesis by combinational analyses of DNA microarray and two-dimensional protein electrophoresis. The expression of the two genes decreased in the tumorigenic cells compared to parent cells. We found that one of the two genes actually regulated tumorigenic potential of the mouse fibroblast cells. We expect to further confirm this finding after examining expressions of those genes in a variety of human tumor tissues and rodent spontaneous arising tumors.