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PubMed2002

Antigen levels of the urokinase-type plasminogen activator and its gene polymorphisms in colorectal cancer.

We analysed the distribution of genotypes of two polymorphisms in the urokinase-type plasminogen activator (uPA) gene: C-->T substitution in exon 6 and T-->C substitution in intron 7 in 52 subjects with colorectal cancer. Genotypes were determined in tumour tissue and distant mucosa samples by allele-specific polymerase chain reaction. The antigen levels of uPA in cancer tissue were higher than in distant mucosa as measured by enzyme-linked immunosorbent assay. The level of uPA antigens in cancer samples with the C/C genotype of C-->T polymorphism in exon 6 was higher than in samples with C/T and T/T genotypes. No differences in the level of uPA antigens between the alleles of the intron 7 T-->C polymorphism were found. As uPA can be involved in cancer invasion and metastasis, C/C genotype in exon 6 of uPA gene can be further considered as being related to colorectal cancer progression.

Aged↗

PubMed2004

Colorectal cancer and the relationship between genes and the environment.

Colorectal cancer (CRC) is a significant cause of morbidity and mortality in developed countries, with both genetic and environmental factors contributing to the etiology and progression of the disease. Several risk factors have been identified, including positive family history, red meat intake, smoking, and alcohol intake. Protective factors include vegetables, calcium, hormone replacement therapy, folate, nonsteroidal anti-inflammatory drugs, and physical activity. The interaction between these environmental factors, in particular diet and genes, is an area of growing interest. Currently, oncogenes, tumor suppressor genes, and mismatch repair genes are believed to play an essential role in colorectal carcinogenesis. When considering the genetics of CRC, only 10% of cases are inherited and only 2-6% can be ascribed to the highly penetrant genes, such as APC, hMLH and hMSH2. Lower penetrance genes combined with a Western-style diet contribute to the majority of sporadic CRCs. The purpose of this article is to give a brief overview of the epidemiologic studies that have been conducted and present the major findings. Here, we examine the molecular events in CRC, with particular focus on the interaction between genes and environment, and review the most current research in this area.

Colorectal Neoplasms↗

PubMed2001

[Structure and expression of colorectal cancer related Immunoglobulin novel gene SNC73].

OBJECTIVE: To study the structure and function of a colorectal cancer-associated gene SNC73 obtained by subtractive hybridization technique. METHODS: Direct sequencing was performed on cDNA of SNC73 gene. In situ-max fluorescence in situ hybridization was used in chromosome mapping of SNC73. Expression of SNC73 in various cancer cell lines and differential expression between normal mucosa and colorectal cancer tissue were examined by Northern blotting and RT-PCR. Expression of SNC73 in colorectal epithelium was detected by in situ hybridization and in situ PCR. RESULTS: Open reading frame prediction showed that SNC73 encodes a peptide identical to the constant region of an IgA molecule in the carboxyl-terminus. The gene was mapped to human chromosome 14q32. The expression of SNC73 in colorectal cancer tissue and that in normal mucosa was different (P < 0.05). SNC73 was lowly expressed in colorectal epithelium. CONCLUSION: Decrease in SNC73 expression may be a potential genetic marker for the development of colorectal cancer. An immunoglobulin alpha-1 gene can be expressed in non-lymphoid cells.

Blotting, Northern↗

PubMed2005

Genomic screens for genes upregulated by demethylation in colorectal cancer: possible usefulness for clinical application.

Inactivation of tumor suppressor genes may result in clinically aggressive tumors and poor prognoses for cancer patients. This study was conducted to investigate the clinical significance of genomic screens for genes upregulated by demethylation in colorectal cancer. We performed a comprehensive survey of commonly inactivated genes in colorectal cancer through the functional reactivation of epigenetically silenced genes by 5-Azacytidine, using cDNA microarrays containing 12,814 genes. We then investigated the clinical significance of the identified gene in colorectal cancer patients. Among 41 candidate genes identified by this microarray analysis, 31 (76%) harbored CpG islands, and many of the genes were associated with cancer-testis antigens, Wnt inhibitors, growth factors, and cell cycle regulators. Subsequent analysis by quantitative RT-PCR confirmed the reliability of our microarray strategy. In order to elucidate the potential clinical significance of these identified genes, we selected one of these genes, apolipoprotein D (apo D), and investigated its mRNA expression in 63 colorectal cancer patients using quantitative real-time RT-PCR. The mean expression level of Apo D mRNA was significantly lower in cancerous tissues than in non-cancerous tissues (p < 0.01), and a lower expression of Apo D was significantly correlated with lymph node metastasis (p < 0.05), advanced stages (p < 0.05) and poorer overall survival (p < 0.05). These results indicated that a genomic screen for genes upregulated by demethylation may be a useful approach for the identification of genes that are of clinical significance in colorectal cancer patients.

Aged↗

PubMed1993

Mutation in the nm23 gene is associated with metastasis in colorectal cancer.

The human nm23 gene, a candidate metastatic suppressor gene, consists of two genes, nm23-H1 and nm23-H2. The potential mutation in the nm23-H1 gene was examined in colorectal cancer using a reverse transcription polymerase chain reaction amplification followed by DNA sequencing analysis. Genomic alterations in the nm23 gene were also examined by Southern hybridization. Genetic alterations either as a deletion in the coding sequence of nm23-H1 or as an allelic deletion were detected in four among eight colorectal adenocarcinomas associated with metastases in lymph nodes, lung, or liver. No alteration was observed in 12 additional colorectal cancer specimens without metastasis. These results provide first evidence for novel mutation in the nm23 gene and demonstrate a correlation between the mutation in the nm23 gene and metastasis in colorectal oncogenesis which suggests that the nm23 gene plays a role in the causation of metastasis.

Alleles↗

PubMed1991

Regulation of the expression of major histocompatibility complex class I genes in human colorectal cancer.

Products encoded by the major histocompatibility complex class I genes are down-regulated in many tumors. The under-representation of HLA antigens in human tumors is usually associated with a poor prognosis. In this report, the expression of HLA genes in human colorectal carcinomas was studied using HLA-A and HLA-B locus-specific probes. Over 50% of the colorectal carcinomas studied showed a reduction in the amount of steady-state HLA mRNA. For some carcinomas, non-coordinated regulation of the HLA-A and HLA-B genes was observed. The HLA expression in some, but not all cases, could be enhanced by gamma-interferon. Over 60% of the colorectal carcinomas also expressed high level of the c-myc oncogene mRNA. However, no correlation could be made between the increase of c-myc expression and the down-regulation of the HLA genes.

Carcinoma↗

PubMed1999

A profile of differentially expressed genes in primary colorectal cancer using suppression subtractive hybridization.

As a step towards understanding the complex differences between normal cells and cancer cells, we have used suppression subtractive hybridization (SSH) to generate a profile of genes overexpressed in primary colorectal cancer (CRC). From a 35¿ omitted¿000 clone SSH-cDNA repertoire, we have screened 400 random clones by reverse Northern blotting, of which 45 clones were scored as overexpressed in tumor compared to matched normal mucosa. Sequencing showed 37 different genes and of these, 16 genes corresponded to known genes in the public databases. Twelve genes, including Smad5 and Fls353, have previously been shown to be overexpressed in CRC. A series of known genes which have not previously been reported to be overexpressed in cancer were also recovered: Hsc70, PBEF, ribophorin II and Ese-3B. The remaining 21 genes have as yet no functional annotation. These results show that SSH in conjunction with high throughput screening provides a very efficient means to produce a broad profile of genes differentially expressed in cancer. Some of the genes identified may provide novel points of therapeutic intervention.

Adenocarcinoma↗

PubMed2006

Aberrant promoter methylation of multiple genes during multistep pathogenesis of colorectal cancers.

Aberrant methylation of 5'gene promoter regions associated with gene silencing is an epigenetic phenomenon responsible for silencing of tumor suppressor genes in many cancer types. The aims of our study were to study the role of methylation of a large panel of genes during multistage pathogenesis and to correlate our findings with patient age and other clinico-pathological features. We investigated the aberrant promoter methylation profile of 19 genes in 92 colorectal cancers (CRCs) and corresponding nonmalignant epithelia (NME) (n = 57), and selected 15 genes for studying 26 colorectal adenomas (CAs). On the Basis of our results, the genes could be divided into 3 groups. Group 1 consisted of 13 genes whose methylation was tumor-specific. For 8 of these genes, the methylation frequencies in CAs were similar to those of CRCs, but significantly different from the frequencies in NME. Group 2, consisting of 2 genes demonstrating little or no methylation, were present in any sample type. In Group 3, consisting of 4 genes, relatively frequent methylation was present in both CRCs and NME, and the differences between these specimen types were not significant. Methylation of Group 1 genes were tightly correlated with each other, and these genes demonstrated increased methylation frequencies in CRCs with increasing age. Methylation was not correlated with other clinico-pathological features. In general, methylation frequencies of CAs were intermediate between CRCs and NME. Our study constitutes the most comprehensive methylation profile of CRCs, demonstrates that methylation commences early during CRC pathogenesis and is an age-related phenomenon.

Aged↗

PubMed2006

Surveillance colonoscopy in individuals at risk for hereditary nonpolyposis colorectal cancer: an evidence-based review.

PURPOSE: Surveillance colonoscopy plays an important role in the management of asymptomatic patients known to carry and suspected of carrying hereditary nonpolyposis colorectal cancer gene mutations. Although the shortest interval between surveillance examinations may seem to offer the most benefit to patients, excessive use of this procedure may have unwanted consequences. This study was designed to evaluate the evidence and make recommendations regarding the optimal frequency of surveillance colonoscopy and the age at which to initiate surveillance based on the best available evidence. METHODS: MEDLINE was searched for all articles assessing surveillance colonoscopy from 1966 to 2004 by using the MESH terms "hereditary nonpolyposis colorectal cancer" and "screening." The evidence was systematically reviewed and a critical appraisal of the evidence was performed. RESULTS: There are no randomized, controlled, clinical trials examining the frequency of surveillance colonoscopy in hereditary nonpolyposis colorectal cancer. Three cohort studies were identified for review. There is one cohort study of good quality that provides evidence that surveillance colonoscopy every three years in patients with hereditary nonpolyposis colorectal cancer reduces the risk of developing colorectal cancer and the risk of death. The two remaining cohort studies provide poor evidence on which to make a recommendation. CONCLUSIONS: The best available evidence supports surveillance with complete colonoscopy to the cecum every three years in patients with hereditary nonpolyposis colorectal cancer (B recommendation). There is no evidence to support or refute more frequent screening. Further research is required to examine the potential harms and benefits of more frequent screening. However, given the potential for rapid progression from adenoma to carcinoma and missing lesions at colonoscopy, there is consensus that screening more frequently than every three years is required.

Colonoscopy↗

PubMed1997

Netrin and netrin receptor expression in the embryonic mammalian nervous system suggests roles in retinal, striatal, nigral, and cerebellar development.

The netrins are laminin-like axon guidance molecules that are conserved among Caenorhabditis elegans, Drosophila, and vertebrates and that have chemoattractive and chemorepellant properties. To study the possible actions of this gene family in the developing and adult mammalian nervous systems, we have cloned a partial cDNA which corresponds to a region conserved among chick netrin-1, netrin-2, and unc-6 and studied its expression and that of a netrin receptor, dcc, the deleted in colorectal cancer gene, in the developing and adult rat CNS. The localization of cells expressing netrin or dcc suggests that these genes, in addition to their actions in defining the ventral midline, may act in controlling retinal ganglion cell axon guidance in the optic nerve, cell migration in the developing cerebellum and olfactory epithelium, and development and maintenance of connections to the substantia nigra and corpus striatum.

Aging↗

PubMed1997

N-acetyltransferase 2 genotype in colorectal cancer and selective gene retention in cancers with chromosome 8p deletions.

BACKGROUND: Genetic polymorphisms in N-acetyltransferase (NAT2) can change the normally fast acetylation of substrates to slow acetylation, and have been associated with the development of some cancers. The NAT2 locus may also suffer dysregulation during cancer progression, as the gene resides on chromosome 8p22, a region which is frequently deleted in colorectal cancer. SUBJECTS AND METHODS: A polymerase chain reaction based method was used to determine NAT2 genotype in 275 patients with colon cancer and 343 normal control DNAs. Within the cancer group, 65 cases known to contain deletions in chromosome 8p were examined for loss of heterozygosity at the NAT2 locus. RESULTS: Overall, there was no statistical difference in frequency or distribution of NAT2 alleles and genotype between colon cancer and control groups. There was a significant association between the slow acetylation genotype and early age of onset. NAT2 genotype did not vary with other clinical features of colon cancer, which included Dukes's stage, site of tumour, and sex. Of 48 informative cases, only three (6%) showed loss of heterozygosity, indicating that the NAT2 locus is not commonly deleted in colorectal cancer. This suggests that NAT2 is retained during the process of allele loss possibly because of its proximity to a gene necessary for cell viability. CONCLUSIONS: NAT2 does not play a major role in colorectal cancer risk, but may influence risk in some age groups. The nature of the loss of heterozygosity at the chromosome 8p site is complex and is worthy of further study.

Acetylation↗

PubMed1995

Neurofibromatosis 2 gene in human colorectal cancer.

Colon cancers commonly have allelic losses of chromosome 22q, which suggests the presence of a tumor suppressor gene on 22q. The candidate tumor suppressor gene on 22q is the neurofibromatosis 2 (NF2) gene. Using single strand conformation polymorphism (SSCP) analysis, we screened 24 pairs of colorectal cancer and adjacent normal mucosa, as well as 10 colon cancer cell lines from non-NF2 patients, for mutations in the coding sequence of the NF2 gene. Two SSCP variants, one in exon 14 and another one in exon 16, were detected in two of the sporadic colorectal cancers, but not in adjacent normal mucosa samples. Sequencing of these variants in one tumor detected an A-to-G transition in bp 1459 of the NF2 cDNA, resulting in the change of Ile to Val at codon 487 of merlin, the NF2 protein product. The other tumor showed a 2-bp (CT) deletion in the intronic sequence of the alternatively spliced exon 16. These results suggest that the NF2 gene is probably involved in some colorectal tumors, but is not the critical chromosome 22q tumor suppressor gene involved in colon tumorigenesis.

Base Sequence↗

PubMed1991

Common regions of deletion on chromosomes 5q, 6q, and 10q in renal cell carcinoma.

Relatively frequent losses of heterozygosity on chromosomes 5q, 6q, and 10q, in addition to loss of heterozygosity on the short arm of chromosome 3, have been observed in renal cell carcinomas. As the first step toward isolation of tumor suppressor genes on these three chromosomal arms, we used six restriction fragment length polymorphism markers for 5q, nine for 6q, and eight for 10q to identify regions commonly deleted in a panel of 64 renal cell carcinomas. Allelic losses were common at chromosome 5q21, the region where the MCC (mutated in colorectal cancer) gene was recently identified; at chromosome 6q27; and at chromosome 10q21-23. Furthermore, as association was observed between accumulation of allelic losses on these three chromosomal arms and progression of tumors. Loss of heterozygosity on chromosome 5 showed a correlation with the histopathological grade of a given tumor and the incidence of distant metastasis.

Blotting, Southern↗

PubMedDate not supplied

Prognostic value of circulating KRAS2 gene mutations in colorectal cancer with distant metastases.

While tissue KRAS2 mutations have been extensively investigated, the role of circulating mutant KRAS2 gene in patients with colorectal carcinoma remains obscure. The aim of the present study was to explore the prognostic significance of circulating KRAS2 gene mutational status in subjects undergoing primary treatment for colorectal cancer. Codon 12 KRAS2 mutations were examined in DNA samples extracted from the serum of 86 patients with colorectal cancer and were compared with the KRAS2 status of their primary tumors. Tissue and serum KRAS2 status was compared with other clinicopathological variables (including CEA and CA 19-9 levels) and with cancer-related survival. KRAS2 mutations were found in tissue samples of 28 patients (33%); serum KRAS2 mutations were detected in 10 of them (36%). Serum KRAS2 status was significantly associated with Dukes' stage D (p=0.001) and with preoperative CA 19-9 levels (p=0.01). At multivariate analysis, cancer-related survival was associated with Dukes' stage (p<0.0001), CEA level (p=0.02), and mutant circulating KRAS2 (p=0.01). All 7 stage D patients with serum KRAS2 mutations died of the disease within 24 months of primary treatment; cancer-related survival was significantly better in 9 stage D patients without serum KRAS2 mutations, with 5 patients (56%) alive after 24 months and 1 patient (13%) alive after 44 months. Residual disease after surgery was evident in all 7 stage D patients with mutant circulating KRAS2, and in 5 out of 9 stage D patients without serum mutations. Serum KRAS2 status may impact substantially on the management of stage D colorectal carcinoma, since it appears to cor-relate with prognosis in this patient subgroup.

Adult↗

PubMed2004

An association of polymorphism of DNA repair genes XRCC1 and XRCC3 with colorectal cancer.

Variability in DNA repair genes may contribute to human cancer risk. We performed a case-control study (51 cases and 100 controls) to test the association between two polymorphisms: Arg399Gln in the XRCC1 gene and Thr241Met in the XRCC3 gene and colorectal cancer risk. Genotypes were determined in tumour tissue and distant mucosa samples by PCR RFLP with the NciI restriction enzyme for XRCC1 and NcoI for XRCC3. Cancer occurrence was strongly associated with the XRCC3 Met/Met polymorphic variant (OR = 9.45; (95% CI 8.77-11.65)), whereas Thr/Thr and Thr/Met variants were associated with significant reduction in colorectal cancer risk (OR = 0.16; 95% CI 0-0.26 and OR = 0.26; 95% CI 0.25-0.27, respectively). Weak association was found between the XRCC1 Arg/Arg and Gln/Gln variants and the risk of colorectal cancer (OR = 1.28; 95% CI 1.00-1.84 and OR = 1.13; 95% CI 0.85-2.34, respectively). Gene-gene interaction between the XRCC1 Arg/Arg and XRCC3 Met/Met homozygous variants slightly increased the risk (OR = 10.50; 95% CI 5.67-14.79). Both polymorphisms were not associated with colorectal cancer progression.

Adenocarcinoma↗

PubMed2004

Frequent aberrant methylation of the CDH4 gene promoter in human colorectal and gastric cancer.

Gene promoter methylation causes loss of tumor suppressor genes function in human cancer. Here, we show that the CDH4 gene, a member of the cadherin family encoding for R-cadherin, contains a CpG island located at the 5' of the first exon, which functions as a promoter element and is frequently affected by methylation in human cancer. By using methylation-specific PCR and reverse transcription-PCR in human cancer cell lines, promoter methylation could be directly linked to loss of gene expression. After treatment with the demethylating agent 5-aza-2-deoxycytidine, expression could be restored. Analysis of human primary tumors revealed that the CDH4 gene is methylated in 78% (38 of 49) of colorectal and 95% (20 of 21) of gastric carcinomas. CDH4 methylation was not detected in nonneoplastic colonic (0 of 10) and stomach (0 of 10) tissues or in peripheral blood (0 of 17). CDH4 methylation was detected in histologically normal tissues located in proximity of the neoplasms, indicating that CDH4 methylation is an early event in gastrointestinal tumor progression. We also proved that CDH4 methylation can be revealed in the peripheral blood of cancer patients. Our results indicate that CDH4 may act as a tumor suppressor gene in human gastrointestinal tumors and can potentially be used as an early diagnostic marker for gastrointestinal tumorigenesis.

Base Sequence↗

PubMed2005

Functional analysis of PIK3CA gene mutations in human colorectal cancer.

Mutations in the PIK3CA gene, which encodes the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), have been reported in human cancers, including colorectal cancer. Most of the mutations cluster at hotspots within the helical and kinase domains. Whereas H1047R, one of the hotspot mutants, is reported to have elevated lipid kinase activity, the functional consequences of other mutations have not been examined. In this study, we examined the effects of colon cancer-associated PIK3CA mutations on the lipid kinase activity in vitro, activation of the downstream targets Akt and p70S6K in vivo and NIH 3T3-transforming ability. Of eight mutations examined, all showed increased lipid kinase activity compared with wild-type p110alpha. All the mutants strongly activated Akt and p70S6K compared with wild-type p110alpha as determined by immunoblotting using phospho-specific antibodies. These mutants also induced morphologic changes, loss of contact inhibition, and anchorage-independent growth of NIH 3T3 cells. The hotspot mutations examined in this study, E542K, E545K, and H1047R, all had high enzymatic and transforming activities. These results show that almost all the colon cancer-associated PIK3CA mutations are functionally active so that they are likely to be involved in carcinogenesis.

Animals↗

PubMed2000

Rare syndromes and genetic testing for colorectal cancer.

The genes responsible for each of the inherited syndromes of intestinal polyposis and colorectal cancer are now known. This knowledge has led to genetic testing for syndrome diagnosis and for determining which persons in an affected family actually have the condition. Genetic testing has also allowed a more precise clinical characterization of each of the syndromes and their subtypes. Optimal application of genetic testing, proper cancer prevention, and management of nonmalignant features of each of the syndromes are the next goals. This report summarizes each of the syndromes, their genetics, and management and provides an approach for genetic testing.

Adult↗