Colorectal carcinoma is the second most common cause of cancer deaths in the U.S.A. At present, prognostication is based mainly on pathologic staging (Dukes' classification). Molecular probes have not been applied in large groups of patients to determine if molecular markers can be used to predict clinical outcome and assist in selecting appropriate therapy. The utility of probes in defining the pathogenesis of primary human colorectal carcinoma has not been studied extensively. We propose to evaluate a select group of markers in unique subsets of patients with colorectal carcinoma whose tumors have metastatic phenotype as defined by pathologic and clinical criteria. Our long-term goal is to find molecular probes which will assist in providing appropriate therapy by identifying patients with high risk of metastases. Our hypothesis to be tested is that primary colorectal carcinomas with propensity to metastasize (i.e. which show metastatic phenotype) demonstrate interrelated pathogenetic cellular markers, including mutation of the c-Ki-ras gene with expression of the mutant ras p21 gene product, DNA aneuploidy, and high activity of ornithine decarboxylase with high concentrations of polyamines and rapid tumor cell proliferation.
Our specific aims are: (1) To begin collaborative exchange of colorectal carcinoma specimens from the tissue banks of the Bowel Tumor Working Group at The Johns Hopkins Hospital and St. Mark's Hospital, London, England. This will provide adequate pathologically well-defined populations of prospectively identified patients with definable clinical outcomes for studies of the potential markers described in Specific Aims 2 through 4. (2) To assess colorectal carcinomas for mutation of c-Ki-ras, c-Ha-ras, and N-ras genes by hybridization assay and determine ras gene product p21 expression by immunoblotting, enzyme-linked immunosorbent assay, and immunohistochemistry using a panel of monoclonal and polyclonal antibodies against native and mutated p21. (3) To assess colorectal carcinomas for DNA aneuploidy by flow cytometry. (4) To assess colorectal carcinomas for activity of ornithine decarboxylase by radiometric assay, concentrations of polyamines by high-pressure liquid chromotography, and cell proliferation by immunohistochemistry with monoclonal antibody Ki-67 against proliferating cells. (5) To analyze using appropriate statistical methods the data for the various markers in relation to each other as well as to the pathologic features of the colorectal carcinomas, the presence of metastases, and patient survival.
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