Potential biomarkers of colorectal adenoma-dysplasia-carcinoma progression: mRNA expression profiling and in situ protein detection on TMAs reveal 15 sequentially upregulated and 2 downregulated genes.

BACKGROUND

As most colorectal cancers (CRC) develop from villous adenomas, studying alterations in gene expression profiles across the colorectal adenoma-dysplasia-carcinoma sequence may yield potential biomarkers of disease progression.

METHODS

Total RNA was extracted, amplified, and biotinylated from colonic biopsies of 15 patients with CRC, 15 with villous adenoma and 8 normal controls. Gene expression profiles were evaluated using HGU133Plus2.0 microarrays and disease progression associated data were validated with RT-PCR. The potential biomarkers were also tested at the protein level using tissue microarray samples of 103 independent and 16 overlapping patients.

RESULTS

17 genes were validated to show sequentially altered expression at mRNA level through the normal-adenoma-dysplasia-carcinoma progression. Prostaglandin-D2 receptor (PTGDR) and amnionless homolog (AMN) genes revealed gradually decreasing expression while the rest of 15 genes including osteonectin, osteopontin, collagen IV-alpha 1, biglycan, matrix GLAprotein, and von Willebrand factor demonstrated progressively increasing expression. Similar trends of expression were confirmed at protein level for PTGDR, AMN, osteopontin and osteonectin.

CONCLUSIONS

Downregulated AMN and PTGDR and upregulated osteopontin and osteonectin were found as potential biomarkers of colorectal carcinogenesis and disease progression to be utilized for prospective biopsy screening both at mRNA and protein levels. Gene alterations identified here may also add to our understanding of CRC progression.