Expression of putative stem cell genes Musashi-1 and beta 1-integrin in human colorectal adenomas and adenocarcinomas

Recent studies revealed that Musashi-1and beta 1-integrin were putative stem cell genes. Overexpressions of Musashi-1 and beta 1-integrin have been reported in some tumor tissues and cell lines. This study was to detect expressions of the two genes in colorectal adenomas and carcinomas and to analyze the correlation between Musashi-1 and beta 1-integrin. Musashi-1 and beta 1-integrin immunoreactivity was studied immunohistochemically in tissue microarray-based samples containing 69 colorectal adenocarcinomas, eight normal mucosa, and eight adenomas, and their messenger RNA (mRNA) expression level was detected by RT-PCR in resected specimens including the three types of tissue. A percentage of 66.7% (46/69) and 59.2% (41/69) of colorectal adenocarcinomas were immunoreactive with Musashi-1 and beta 1-integrin, respectively. The expressions of Musashi-1 and beta 1-integrin protein were significantly higher in tissue samples of stage III than those of stage I-II (P = 0.0252; P = 0.0018, respectively). beta 1-integrin expression was higher in group of adenocarcinomas than that of adenomas (P = 0.0276). Musashi-1 expression was closely correlated with beta 1-integrin (rs = 0.631, P = 0.0001). Significant differences of Musashi-1 and beta 1-integrin mRNA expression levels were found between the normal colorectal mucosa, adenoma, and adenocarcinoma tissues (P = 0.01; P = 0.03, respectively). Musashi-1 and beta 1-integrin may be involved in human colorectal tumor carcinogenesis and progression. Our observations also indicate the need for further investigations to test in vivo whether cells with these markers have stem cell properties.