We prospectively followed a cohort of 446 unaffected carriers of an MMR gene mutation (MLH1, n = 161; MSH2, n = 222; MSH6, n = 47; and PMS2, n = 16) and 1,029 their unaffected relatives who did not carry a mutation every 5 years at recruitment centers of the Colon Cancer Family Registry.
We conclude that polymorphisms in some insulin-related genes are associated with an increased risk of colon cancer with specific KRAS2 and TP53 mutations, implying a link between these genetic changes and specific mutational pathways in carcinogenesis.
We examined the anti-proliferative effect of miR-143#12 and the mechanism in human colon cancer DLD-1 cell (G13D) and other cell types harboring K-Ras mutations.
Our findings suggest APC mutations alter regulation of both beta- and gamma-catenin, perhaps explaining why the frequency of APC mutations in colon cancer far exceeds that of beta-catenin mutations.
A point mutation at codon 12 of the K-ras gene was found, while no alterations were noted in the p53 gene, whose mutations are frequent in colon cancers.
In this study, we assessed and compared the mutational status of KRAS, NRAS, and PIK3CA in PDCs and corresponding main tumor tissue of 25 CCs with KRAS mutations.
This study aims to characterize colon cancer with regard to KRAS, BRAF, and PIK3CA mutations, microsatellite instability (MSI), and average DNA copy number, in connection with tumour dissemination and recurrence in patients with colon cancer.
Female patients and older group harbored a higher KRAS mutation (P = 0.018 and P = 0.031, respectively); BRAF (V600E) mutation showed a higher frequency in colon cancer and poor differentiation tumors (P = 0.020 and P = 0.030, respectively); proximal tumors appeared a higher PIK3CA mutation (P<0.001) and distant metastatic tumors shared a higher NRAS mutation (P = 0.010).
Physical inactivity, large body mass index, cigarette smoking, using aspirin/nonsteroidal anti-inflammatory drugs, and other dietary factors appeared to be comparably associated with colon cancer in those with and without p53 mutations.
In addition, Pyrosequencing proved superior to dideoxy sequencing in the detection of KRAS mutations from DNA mixtures of paraffin-embedded colon cancer and normal tissue as well as from paraffin-embedded pancreatic cancers.
To demonstrate the program, the mutational spectra of single base substitutions in the p53 gene are compared in (i) bladder cancers from smokers and non-smokers, (ii) small-cell lung cancers, non-small-cell lung cancers and colon cancers and (iii) hepatocellular carcinomas from high- and low-aflatoxin exposure groups. p53 mutations differ in several important aspects from a typical mutational spectra experiment, where a homogeneous population of cells is treated with a specific mutagen and mutations at a specific locus are recovered by phenotypic selection.
K-Ras proteins containing this tandem duplication or a similar five amino acid E62_A66dup mutation identified in lung and colon cancers transform the growth of primary myeloid progenitors and of Ba/F3 cells.
Case-control studies of genetic polymorphisms in DNA repair enzymes suggest that the common variant Ser326Cys in OGG1 may be a risk factor for lung cancer, whereas a rare variant in OGG1 and germ line mutations in the corresponding mismatch repair gene MYH are risk factors for hereditary colon cancer.
The second form of genetic instability is characterized by the development of p53 gene abnormalities that result in gross aneuploidy and multiple structural chromosomal changes. p53/aneuploidy affects most colon cancers, breast cancers, and many other solid tumors.
In the present study, a large family with evidence of polyposis and colon cancer was screened for the mutations of the p53 gene and protein overexpression.
Using data from the Colon Cancer Family Registry, we compared the proportion of childhood cancers (diagnosed before 18 years of age) in the first-, second-, and third-degree relatives of 781 probands with a pathogenic mutation in one of the MMR genes; MLH1 (n = 275), MSH2 (n = 342), MSH6 (n = 99), or PMS2 (n = 55) or in EPCAM (n = 10) (Lynch syndrome families), with that of 5073 probands with MMR-deficient colorectal cancer (non-Lynch syndrome families).
Human colon cancer development is associated with the accumulation of mutations and deletions in the suppressor genes DCC, APC and p53 and mutations in the dominant oncogene K-ras, with loss of wild type alleles.