ORIGINAL ARTICLE

Molecular changes in the Ki-ras and APC genes in primary colorectal carcinoma and synchronous metastases compared with the findings in accompanying adenomas

P Zauber¹, M Sabbath-Solitare¹, S P Marotta¹, D T Bishop²

¹ Saint Barnabas Medical Center, 22 Old Short Hill Road, Livingstone, NJ 07039, USA
² Genetic Epidemiology Division, Cancer Research UK Clinical Centre in Leeds, St James’s University Hospital, Leeds, UK

Correspondence to:
Correspondence to:
Dr P Zauber, Saint Barnabas Medical Center, 22 Old Short Hill Road, Livingstone, NJ 07039, USA;
pzauber{at}aol.com

Aims: To compare the molecular genetic changes in the Ki-ras and adenomatous polyposis coli (APC) genes between colorectal carcinomas and synchronous metastases, and then to compare and contrast those changes with previously reported changes in the two genes between these carcinomas and accompanying adenomas. This expanded comparison would provide greater understanding of the progression of molecular changes in neoplastic tissue during the development of malignancy from a benign adenoma to carcinoma and then to metastatic spread of the malignancy.

Methods: DNA was extracted from paraffin wax embedded tissue. This was followed by polymerase chain reaction and gel electrophoresis for mutations in the Ki-ras gene using single stranded conformational polymorphism analysis. Amplification of a CA repeat marker was used to assess loss of heterozygosity (LOH) at the APC gene.

Results: The findings for the Ki-ras gene in 42 paired carcinomas and synchronous metastases were identical, regardless of whether or not the carcinoma and its companion adenoma had identical Ki-ras findings. The results of APC LOH for 39 paired carcinomas and synchronous metastases were also identical, whether or not the carcinoma and its companion adenoma had identical APC LOH findings. Results were uninformative for three pairs.

Conclusions: With respect to these two genes, a carcinoma may be discordant from its companion adenoma, but the metastasis remains consistent with the colonic carcinoma.

Keywords: Ki-ras; adenomatous polyposis coli; metastasis; colonic adenoma; colon carcinoma

Abbreviations: APC, adenomatous polyposis coli; LOH, loss of heterozygosity; PCR, polymerase chain reaction; SSCP, single stranded conformational polymorphism

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