Expression of the α1 integrin subunit in CRC samples. (A) The α1 integrin subunit mRNA levels were evaluated by qPCR in 65 sets of colorectal cancers and corresponding resection matched margins. Transcript levels for α1 were found to be increased in tumours relative to their corresponding resection margins in 86% of samples (dotted line: cut off = 2). Expression of the α1 gene was calculated by the ΔΔCt method and normalized to B2M expression. (p < 0.001, One-Sample T Test). (B) To illustrate the individual tendency of paired samples, transcript levels of α1 were expressed as 1/ΔCt in each of the 65 matched margin and corresponding cancers showing the significant tendency for a higher level of expression in cancers (p < 0.001, t-test two-tailed). (C) However, α1 subunit mRNA levels did not correlate with tumour stage (stage 1; 8 patients, stage 2; 23 patients, stage 3; 26 patients and stage 4; 8 patients). (D) Integrin α1 expression at the protein level was analysed by immunohistochemistry on a TMA containing 65 colorectal tissues and their corresponding resection margins only considering epithelial staining. As illustrated in Figure 1, α1 immunostaining was scored as 0: negative or weak, 1: moderate or 2: strong staining. Results show that α1 staining in carcinoma vs normal epithelial cells from the matched controls was significantly higher (McNemar-Bowker’s test, p < 0.001) in 37 specimens (57%, gray area), similar in 25 specimens (38%) and lower in 3 specimens (5%). (E) The relative α1 integrin subunit expression was classified as negative/weak or moderate/strong. The results show that only 23% of the normal tissues displayed moderate/strong epithelial staining for α1 compared to 65% of cancer cells and 97% of the peri-tumoral stromal cells. Bars represent 95% confidence level.