Plasma membrane calcium ATPase expression in human colon multistep carcinogenesis.

The expression of the plasma membrane Ca(2+) ATPase (PMCA) was analyzed in a series of 84 formalin-fixed and paraffin embedded colon samples including normal mucosa (n = 32), adenoma (n = 19), adenocarcinoma (n = 27), and lymph node metastasis (n = 6) using (i) immunohistochemistry, (ii) mRNA in situ hybridization, and (iii) quantitative reverse-transcriptase PCR. A marked reduction of PMCA4 protein was observed in high-grade adenoma, colon cancer as well as lymph node metastasis, pointing to its potential role in the progression of cancer. However, PMCA4 RNA transcripts were unchanged or even increased in colon carcinomas, suggesting posttranscriptional regulation of PMCA4 during carcinogenesis.