Figure 1

Expression of PTPRR mRNA in normal colorectal mucosa, polypoid precancerous colorectal lesions, colorectal cancers, and colorectal cancer cell lines. (A): mRNA levels based on normalized raw signal values (y-axis) were detected with the Affymetrix U133 Plus 2.0 arrays in the tissue sample series reported in Sabates-Bellver et al., 2007. (B): The two main isoforms of PTPRR are shown aligned from 5' to 3'. Introns have been reduced to minimal lengths, whereas exon sizes are proportional to their actual lengths. Horizontal bars represent the portions of cDNA that were amplified by qRT-PCR to discriminate between the two isoforms (see Methods). (C) and (D): PTPRR-1 and PTPRR-2 expression was investigated with real time qRT-PCR in a subset of the samples collected for the present study (see Methods). Fold changes were calculated as reported in Methods: For polypoid lesions and colorectal cancers, reference expression was the mean observed in the corresponding normal mucosa samples (indicated as 1); for cell lines, the reference consisted in the mean observed for 9 samples of normal mucosa from 9 patients with adenomas (indicated as 1). The differences between normal mucosa and the other groups of samples were highly significant in panels A, C, and D (all p values < 0.0001; bars: mean SE). (E) and (F): Two colorectal cancer cell lines (HCT116 and HT29) that do not express PTPRR-1 were used for the experiments shown in these panels. Re-activation of PTPRR-1 expression was investigated in cells treated with agents that act, through different mechanisms, on DNA and chromatin (see Methods). 5-Aza-dC, 5-Aza-2'-deoxycytidine; TSA, Trichostatin A; DZNep, 3-Deazaneplanocin A. Results are expressed relative to reference expression (mean observed in 9 different samples of normal mucosa, indicated as 1).