CD133 expression in renal cell carcinoma (RCC) is correlated with nuclear hypoxia-inducing factor 1α (HIF-1α)

In our previous study, we have found that the hypoxia-inducible factor 1 alpha (HIF-1 alpha) is upregulated in renal cell carcinoma (RCC) tissues compared with para-cancer normal tissues by 2-dimensional polyacrylamide gel electrophoresis. It was reported that hypoxic conditions were correlated with cancer stem cell generation and HIF-1 alpha acted as a transcription regulator in nuclear HIF-1 alpha expression. Therefore, in this study we investigate the relation between CD133 and nuclear HIF-1 alpha expression levels in RCC tissues. In this study 61 RCC tissues from the patients that treated with radical nephrectomy were collected. Then, we investigated the expression of CD133 and nuclear HIF-1 alpha expression by immunohistochemistry. To verify the relation between CD133 and nuclear HIF-1 alpha expression, we treated 786-O cells with cobalt chloride. The expression of CD133 on 786-O cells was analyzed by flowcytometry. The immunohistochemical study showed that CD133 was correlated with tumor stage and metastatic stage, whereas nuclear HIF-1 alpha had no association with clinicopathological parameters. However, the expression of nuclear HIF-1 alpha was correlated with CD133. The CD133 expression in 786-O cells was enhanced by cobalt chloride, which meant that CD133 expression was affected by hypoxia. Our study showed that in RCC, CD133 expression was strongly related to nuclear HIF-1 alpha and the expression of CD133 might be upregulated under hypoxia environment.