[Real-time PCR analysis of beta-catenin mRNA in sporadic colorectal cancers]

To detect beta-catenin mRNA levels in sporadic colorectal cancers (SCRC) and adjacent normal colorectal mucosa, and to investigate the association between the beta-catenin mRNA level and its aberrant expression and clinicopathological parameters.

The concentration of beta-catenin mRNA in 81 SCRCs and 28 adjacent normal colorectal mucosa specimens was determined by TaqMan real-time quantitative RT-PCR. The ratio of beta-catenin cDNA copies/GAPDH cDNA copies was used to represent the mRNA expression level in different tissues. The beta-catenin protein expression was determined by the EnVision two-step immunohistochemical method.

beta-catenin mRNA levels in SCRCs (2.527 +/- 2.284) were lower than those in the adjacent normal colorectal mucosa (5.003 +/- 3.326), P < 0.05. In addition, beta-catenin mRNA levels in lymph node-positive cases and tumors with ulcerative and infiltrating growth types were significantly lower (1.827 +/- 1.288, 2.202 +/- 2.035) than those in lymph node-negative cases and polypoid growth type tumors (3.359 +/- 2.881, 3.108 +/- 2.610), P < 0.05. No significant difference of beta-catenin mRNA level was found between cases with aberrant beta-catenin cytoplasm or nuclear expression and those without.

SCRCs express lower levels of beta-catenin mRNA than normal colorectal mucosa. Such lower level expression is associated with lymph node metastasis and tumors with ulcerative and infiltrative growth pattern. Aberrant cytoplasmic and nuclear expression of beta-catenin appears unrelated to the lower mRNA levels. Quantitative detection of beta-catenin mRNA may be a useful approach to monitor the biological behavior of SCRCs.