These data not only allow use of flanking markers for presymptomatic diagnosis of FAP but also provide a high-density map of the region for isolation of the APC gene itself and for further assessment of the role of chromosome 5 deletions in the biology of sporadic colorectal cancer.
In colorectal carcinoma, it has been shown that the accumulation of several alterations in ras genes and p53 genes is most important for the conversion of adenoma to carcinoma.
The positive effect on cell proliferation by these mutant p53 proteins is consistent with a role for activated p53 mutants in the genesis of colorectal carcinomas.
While the DCC gene was expressed in most normal tissues, including colonic mucosa, its expression was greatly reduced or absent in most colorectal carcinomas tested.
This dual parameter flow cytometric method, evaluating both DNA ploidy and p53 expression, may prove useful in identifying different biological subgroups of colorectal cancer.
Thus, the frequency and sites of K-ras gene mutation in colorectal carcinoma from familial polyposis coli patients are similar to those in cases of sporadic colorectal carcinoma and may not be the first genetic event linked to the tumorigenesis.
With the use of a slot blot assay, relatively low levels of MDR1 RNA were present in all four gastric carcinoma cell lines, while intermediate or high levels were present in most of the colorectal carcinoma cell lines.
We measured sigmoid and rectal mucosal ODC activity levels in 45 healthy, disease-free subjects with strong family histories of colorectal cancer before and after 2 months, during which daily dietary supplementation with calcium carbonate (to provide 600 mg calcium base) was taken.
We examined the alteration and expression of c-myc gene in 52 human colorectal carcinomas using Southern blot, Northern blot, Western blot and immunohistochemical techniques.
Elevated expression of the MDR1 gene was seen in only four of 18 xenografts of colorectal carcinoma and was not seen in any xenografts of gastric carcinoma.
We conclude that the induction of the CEA-gene expression by sodium butyrate in colorectal-cancer cells is mediated by both transcriptional and post-transcriptional mechanisms, with CEA mRNA stability as one of the major check-points.
The present study demonstrates that transfection of the c-Ha-ras-I oncogene into a poorly differentiated colorectal carcinoma cell line also renders it NK resistant.
Our results suggest that mRNA expression of the laminin-binding protein may be a marker of human colorectal cancer progression and biological aggressiveness.
Expression of mRNAs of carcinoembryonic antigen (CEA) and nonspecific cross-reacting antigen (NCA) genes in colorectal carcinomas and adenomas was investigated by in situ hybridization (ISH) with specific biotinylated probes.
With the use of a slot blot assay, relatively low levels of MDR1 RNA were present in all four gastric carcinoma cell lines, while intermediate or high levels were present in most of the colorectal carcinoma cell lines.