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At least 19 recordsLinked to original sources
PubMed2002

[Clonal chromosomal anomalies in colorectal tumors].

Colorectal tumors constitute a reason of frequent consultation in gastroenterology services in the world. They constitute the second cause of mortality in the world and the fourth cause of mortality for cancer in Venezuela. It usually begins as a polyp that becomes malignant due to a mutation at the level of the genetic code that controls the growth and the repair of cells. The present work reports the clonal chromosomal abnormalities observed in 15 samples from benign tumors as well as malignant colorectal tumors and to relate these findings. There were clonal chromosomal anomalies in 11/15 (73.33%), 4 corresponded to carcinomas and 7 to adenomatous polyps. In 7/11 (63.6%) there were anomalies of the monosomy type in the chromosomes 8 and 22, other anomalies corresponded to trisomy of the chromosomes 11 and 18, and a single case with a structural anomaly that corresponded to a del(17p). The chromosomal anomalies in adenomatous polyposis have been related with the beginning of malignant disease and, in the case of carcinomas, it has been related with progression of the illness toward metastasis and death. The use of this tool could be used as a prognostic factor for patients with non familial adenomatous polyposis.

Adenocarcinoma↗
PubMed2005

[Early diagnosis of colorectal tumors].

Colorectal cancer (CRC) is one of the most common causes of cancer mortality in Western countries. Approximately six percent of the population will develop colorectal cancer during life. Individuals older than 50 years or with a family history for colorectal tumors as well as patients with an inflammatory bowel disease have an increased risk for CRC. A significant reduction of colorectal cancer mortality can be achieved by screening of asymptomatic patients and removal of premalignant adenomatous polyp precursors. Colonoscopy is recognized as the gold standard, but in future virtual colonoscopy might be a reasonable addition. Asymptomatic individuals with an average risk for CRC should be screened from the age of 50 and then every 10 years if the examination showed no pathological findings. When the individual or family history indicate a higher risk for a colorectal neoplasia, screening should begin at the age of 40 or 10 years before the earliest tumor occurrence in the family. Families with hereditary CRC require a special surveillance.

Chronic Disease↗
PubMed1992

Identification of ras oncogene mutations in the stool of patients with curable colorectal tumors.

Colorectal (CR) tumors are usually curable if detected before metastasis. Because genetic alterations are associated with the development of these tumors, mutant genes may be found in the stool of individuals with CR neoplasms. The stools of nine patients whose tumors contained mutations of K-ras were analyzed. In eight of the nine cases, the ras mutations were detectable in DNA purified from the stool. These patients included those with benign and malignant neoplasms from proximal and distal colonic epithelium. Thus, colorectal tumors can be detected by a noninvasive method based on the molecular pathogenesis of the disease.

Adult↗
PubMed2002

Stromelysin-1 promoter mutations impair gelatinase B activation in high microsatellite instability sporadic colorectal tumors.

Colorectal cancers from the mutator phenotype pathway display distinctive pathological features and confer a lesser aggressiveness than colorectal adenocarcinomas originated by the suppressor pathway. The goal of this work was to test whether tumors developed through the mutator pathway could show a decrease in matrix metalloproteinase (MMP) activity. We evaluated levels and activity of gelatinase A (MMP-2) and gelatinase B (MMP-9), as well as stromelysin-1 (MMP-3) expression in 101 sporadic colorectal tumors in consideration of the microsatellite instability (MSI) status of the groups. Gelatinases were analyzed by ELISA and zymography. The MMP-3 study was performed by real-time quantitative PCR. MMP-9 total levels were significantly higher in MSI-H tumors. However, levels of the active MMP-9 form were significantly much lower in this group of tumors. Data from real-time quantitative PCR indicated that levels of MMP-3 for MSI-L/MSS tumors were much higher as compared with those observed in MSI-H cancers (P = 0.033). Moreover, all MSI-H tumors showed nucleotide insertions and/or deletions in MMP-3 promoter. These mutations were not observed in the group of MSI-L/MSS tumors. Our data indicate that the MMP-3 promoter constitutes a novel target of the defective mismatch repair machinery in sporadic colorectal tumors, resulting in a dramatic decrease in the levels of the active MMP-9 form, which may result in a lessened capacity for invasion.

Adenocarcinoma↗
PubMed2005

Impairment of stromelysin-1 transcriptional activity by promoter mutations in high microsatellite instability colorectal tumors.

Colorectal tumorigenesis is characterized by the sequential inactivation of a series of tumor suppressor genes (microsatellite-stable tumors) and genetic or epigenetic alterations in mismatch repair genes in nonpoliposic hereditary tumours and 13% to 15% of sporadic colorectal cancer [high microsatellite instability (MSI-H) tumors]. We hypothesized a molecular mechanism for MSI-H colorectal tumors related to matrix metalloproteinase 3 (MMP-3) promoter mutations, down-regulation of MMP-3 expression, and impairment of MMP-9 activation. We have now analyzed the 2.2-kb full MMP-3 promoter to assess the mutation distribution. The mutations found are restricted to the polymorphic region that includes the zinc-binding protein (ZBP-89) binding element. To show that these alterations were the cause of the low expression of this gene, we have generated three constructs with different MMP-3 promoters (wild type and two mutants) and we have expressed them in SW480 human colorectal cells. The basal transcriptional activity of wild-type MMP-3 promoter was much higher than the mutants activity. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced transcriptional activity of wild-type MMP-3 promoter was 10-fold higher than the mutants activity. Dexamethasone inhibited the basal transcriptional activity of wild-type MMP-3 promoter and of the two mutants found in the MSI-H subgroup of colorectal tumors. Significantly, dexamethasone almost completely blunted the TPA-induced effect on wild-type MMP-3 promoter transcriptional activity and on the mutants, even below their basal activity. Our data show that mutations found in the polymorphic region of the MMP-3 promoter from MSI-H colorectal tumors impair its basal and induced transcriptional activity, which may contribute to their better clinical outcome.

Base Sequence↗
PubMed1995

Inducibility of endogenous tumor necrosis factor by tumor cells from colorectal tumor patients at Dukes stage C as a novel prognostic factor following curative operation.

PURPOSE: It is well known that tumor cells secrete endogenous tumor necrosis factor (en-TNF) as a cytokine when stimulated with lipopolysaccharide (LPS). We, therefore, analyzed the biologic role of en-TNF secreted by tumor cells themselves to learn the prognosis of patients and the susceptibility of tumors to biologic response modifiers in particular. METHODS: Patients with Dukes C colorectal tumors were studied after curative operation to determine the inducibility of en-TNF by their primary cultured cells in response to LPS. RESULTS: Irrespective of the known clinicopathologic factors of the tumors, en-TNF was produced in 21 of a total of 44 patients. The group of patients with clear en-TNF production showed a significantly lower incidence of recurrence and/or metastasis and a higher survival rate than the group without en-TNF production, suggesting a strong correlation between patient prognosis and inducibility of en-TNF. CONCLUSION: Inducibility of en-TNF by tumor cells themselves can be a novel prognostic factor for patients with colorectal tumor, especially of Dukes Stage C.

Biomarkers↗
PubMed1996

ZD2767, an improved system for antibody-directed enzyme prodrug therapy that results in tumor regressions in colorectal tumor xenografts.

ZD2767 represents an improved version of antibody-directed enzyme prodrug therapy. It consists of a conjugate of the F(ab')2 A5B7 antibody fragment and carboxypeptidase G2 (CPG2) and a prodrug, 4-[N,N-bis(2-iodoethyl)amino]phenoxycarbonyl L-glutamic acid. The IC50 of the prodrug against LoVo colorectal tumor cells was 47 microM, and cleavage by CPG2 released the potent bis-iodo phenol mustard drug (IC50 = 0.34 microM). The drug killed both proliferating and quiescent LoVo cells. Administration of the ZD2767 conjugate to nude mice bearing LoVo colorectal xenografts resulted in approximately 1% of injected ZD2767 conjugate localizing/g of tumor after 72 h, and blood and normal tissue levels of the conjugate were 10-50-fold lower. A single round of therapy involving the administration of the prodrug 72 h after the conjugate to athymic mice bearing established LoVo xenografts resulted in approximately 50% of the tumors undergoing complete regressions, tumor growth delays greater than 30 days, and little toxicity (as judged by body-weight loss). Similar studies using a control antibody-CPG2 conjugate that does not bind to LoVo tumor cells resulted in a growth delay of less than 5 days, confirming the tumor specificity of this approach. These studies demonstrate the potential of ZD2767 for the treatment of colorectal cancer.

Animals↗
PubMed2004

Correlation of Skp2 with carcinogenesis, invasion, metastasis, and prognosis in colorectal tumors.

In colorectal tumors, S-phase kinase-associated protein 2 (Skp2) still has numerous important questions unanswered: its expression in adenomas, its correlation with key clinicopathological indices, its association with patient prognosis, its variation in lymph node metastases, and its association with many cell-cycle regulators. To answer these questions in colorectal tumors, Skp2, cyclin A, cyclin B1, cyclin E, CDK2, and Ki67 were immunohistochemically stained in 12 normal mucosa, 36 adenomas, 11 carcinomas in adenomas, 102 primary carcinomas, and 12 paired lymph node metastases; and Skp2 was examined by Western blot in 8 pairs of normal mucosa and carcinomas. Situated in nuclei, Skp2 expression significantly increased from normal mucosa through adenoma to primary carcinoma (p<0.0001), from mild through moderate to severe dysplasia in adenomas (p=0.038), from peripheral adenoma to paired central carcinoma (p=0.0033), and from primary carcinoma to lymph node metastasis (p=0.015), and these increases were confirmed by Western blot. Expression, however, relatively declined significantly in the primary carcinomas showing deep invasion (p=0.0113), lymph nodal metastases (p=0.0268), and poor prognosis for all (p=0.0104) or stage III patients (p=0.0119). High Skp2 was also significantly linked with elevated cyclin A, cyclin B1, cyclin E, CDK2 (in primary carcinomas only), and Ki67 in both adenomas and primary carcinomas. Thus, overexpression of Skp2 is associated with colorectal carcinogenesis and late metastasis to lymph nodes, whereas relative reduction of Skp2 is correlated with local invasion of primary carcinoma.

Aged↗
PubMed2004

Frequent hypermethylation of RASSF1A in early flat-type colorectal tumors.

Flat colorectal tumors, characterized by high-grade dysplasia from early small flat mucosal lesions, exhibit a relatively aggressive clinical behavior and are known for their infrequent K-ras mutations. In this study, we investigated the methylation status of the RASSF1A promoter in association with 3p LOH and K-ras mutations in 48 flat colorectal tumors (39 early carcinomas and nine intramucosal high-grade dysplasias). RASSF1A hypermethylation was detected in 39 of 48 (81.3%) tumors and RASSF1A methylation was also detected in 19 of 39 (49%) normal colonic mucosal tissues. 3p21.3 LOH was detected in 20 of 42 (47.6%) cases, but RASSF1 methylation was detected in cases with LOH (14 cases) and retention of 3p21.3 (20 cases). K-ras mutations were detected in seven of 48 (14.6%) tumors and the concordant occurrence of K-ras mutation and RASSF1A methylation was detected in three of 48 cases (6.3%). Overall, there was a statistically significant mutually exclusive relationship between K-ras mutations and RASSF1A methylation. In conclusion, promoter hypermethylation of RASSF1A is a frequent event and may start early in the background normal mucosa in this tumor type. An alternative cascade of abnormalities in RAS transduction pathways may be responsible for the flat morphology and aggressive nature of flat colorectal neoplasms.

Adult↗
PubMed1999

Immuno-histochemical detection of human telomerase catalytic component, hTERT, in human colorectal tumor and non-tumor tissue sections.

Human telomerase is expressed in germ tissues and in the majority of primary tumors. Cell renewal tissues and some pre-cancerous tissues also have weak telomerase activity. Yet, neither the exact location and frequency of telomerase-positive cells nor the changes in telomerase expression during differentiation or carcinogenesis of individual cells are known. This paper reports on the expression of hTERT (telomerase reverse transcriptase) protein in tumor and non-tumor colorectal tissues by Western blotting and tissue sections by immunohistochemistry using antibodies raised against partial peptides of hTERT. Though telomerase activity and hTERT expression at both mRNA and protein levels were generally higher in tumor part than in non-tumor part, these two were not always correlated: expression of hTERT did not always give rise to high telomerase activity. Colonic carcinoma cell nuclei were stained with anti-hTERT antibodies but not with antigen-preabsorbed antibodies. In normal mucosa, hTERT protein was expressed, though weaker than in carcinoma, in all colonic crypt epithelial cells except those at the tip; the expressing-cell distribution was much wider than that of Ki-67 positive cells which were located at the bottom of the crypt. Isolated crypt contained a significant level of hTERT protein revealed by Western blotting, while having very weak telomerase activity. Telomerase activity was detected in epithelial cells only at the bottom half of the crypt. Specific hTERT-staining was positive in tissue lymphocytes but negative in almost all other stromal cells. It is of interest to see whether a significant level of hTERT expression with low telomerase activity is characteristic of physiologically regenerating tissues containing stem cells. In situ detection of the hTERT protein will permit further analysis of cancer diagnosis and stem cell differentiation.

Blotting, Western↗
PubMed1992

Homotypic aggregation and terminal glycosylation of cells from dissociated human colorectal tumor tissue.

Colorectal tumor tissue directly obtained from the surgeon was dissociated by enzymatical and mechanical disruption into a suspension of single cells of high viability. Homotypic aggregation, sialidase-accessible sialic acid and total fucose content of tumor cells were determined. Aggregation of cells from mucinous tumors was found to be significantly lower than of cells from nonmucinous tissue. The median value of surface-bound sialic acid was lower in strongly aggregating cells compared to nonaggregating cells. Cells from metastasizing tumors showed slightly lower aggregation, but on an average carried more surface-bound sialic acid and were significantly higher fucosylated than cells from nonmetastasizing tumors.

Cell Aggregation↗
PubMed1986

Association of antigen expression and DNA ploidy in human colorectal tumors.

Fifty colorectal tumors were screened by indirect immunofluorescence and flow cytometry for antigen expression using a panel of monoclonal antibodies that recognize determinants preferentially expressed on tumor cells (carcinoembryonic antigen, Y haptenic blood group, 791T/36 defined antigen 791T-P72). Fifty % of the tumors expressed all three antigens, 41%, two, and 9%, one. Over a third reacted strongly with at least one monoclonal antibody, although the majority of tumors stained with a moderate intensity. Extranuclear membranes from tumors showed similar antigen expression to disaggregated tumor cells and were particularly useful for providing the relative tumor:normal tissue binding ratios. The carcinoembryonic antigen specific monoclonal antibody showed the strongest tumor selectivity with a tumor:normal tissue ratio of 24 +/- 7:1. Lack of correlation between expression of the three antigens suggested that the monoclonal antibodies recognizing them may have potential as a "cocktail." One-third of the tumors contained cells with an aneuploid DNA content and expressed elevated levels of carcinoembryonic antigen and Y haptenic blood group antigen when compared to tumors with diploid DNA content. Aneuploid cells within a tumor were also preferentially stained with all of the monoclonal antibodies.

Adenocarcinoma↗
PubMed1998

Increased levels of phosphatidylinositol 3-kinase activity in colorectal tumors.

BACKGROUND: Phosphatidylinositol 3-kinase (PI 3-kinase), an enzyme that phosphorylates inositol phospholipids at the D-3 position of the inositol ring, has been implicated in the signaling pathways regulating cell growth by virtue of its activation in response to various mitogenic stimuli. In spite of the considerable attention PI 3-kinase has received with regard to its possible role in the mitogenic pathways in hematopoietic malignancies, there are few reports of investigations into PI 3-kinase activity in solid tumors. METHODS: Colorectal tumor tissue and normal-appearing colonic mucosa from the same patients were homogenized and solubilized and adjusted to equal protein levels. PI 3-kinase then was immunoprecipitated from 200 microg of the solubilized tissue using a polyclonal antibody to the p85 subunit of PI 3-kinase. PI 3-kinase activity was assessed using phosphatidylinositol as the substrate and the assay product analyzed by thin-layer chromatography. Phosphorylation of phosphatidylinositol in the D-3 position was confirmed by high performance liquid chromatography analysis of deacylated and deglycerated products. RESULTS: Thirty-two of the 37 tumors tested (86%) demonstrated increased PI 3-kinase activity compared with normal-appearing mucosa from the same patients (overall mean increase+/-standard error of the mean=3.8+/-0.6-fold; P < 0.05, Student's t test for paired data). The frequency and extent of increased PI 3-kinase enzyme activity in tumors did not correlate with clinical parameters or the presence of oncogenic ras mutations. CONCLUSIONS: In this study colorectal tumors exhibited enhanced PI 3-kinase activity compared with normal colonic mucosa, raising the possibility that PI 3-kinase may be a potential target for new strategies for the treatment of colorectal carcinoma.

Colorectal Neoplasms↗
PubMed1995

Predominance of normal karyotype in colorectal tumors from hereditary non-polyposis colorectal cancer patients.

We report the cytogenetic study of 9 colorectal tumors arising in patients with hereditary non-polyposis colorectal cancer (HNPCC). According to the cytogenetic classification of colorectal tumors previously proposed by us, 2 cases were of the trisomic type, 2 were of the monosomic type, and 5 had a normal karyotype. This represents a significant excess of tumors with normal karyotype in HNPCC tumors (56%) compared to sporadic cases (10/184 = 5%).

Adenomatous Polyposis Coli↗
PubMed2001

Laterally spreading tumor: clinicopathological study in comparison with the depressed type of colorectal tumor.

AIM: To evaluate the difference between laterally spreading colorectal tumors (LSTs) with depression and depressed-type colorectal tumors. METHODS: Sixteen LSTs showing the appearance of non-distinct, gently sloping central depressions were compared clinicopathologically with 14 depressed-type tumors that were larger than 10 mm in size. RESULTS: The mean size of LSTs with depression was 13.5 +/- 3.4 mm, which was significantly larger than that of the depressed type colorectal tumors (11.2 +/- 1.5 mm). The invasion of the depressed-type colorectal tumors was significantly deeper than that of LSTs with depression, despite the larger size of the LSTs. The surface structures (pit patterns) of both types of tumors were apparently different; the pit patterns of LSTs with depression were almost of the type IIIL pit, while that of the depressed-type tumors were almost of type V pits (P < 0.01). Histologically, LSTs with depression appeared to grow in a superficial replacing manner on the edge of the lesions, while depressed-type tumors grew in an expanding manner. CONCLUSION: It seems appropriate that these LSTs with depression should be distinguished from depressed-type colorectal tumors and regarded as constituting a new clinical entity.

Adenoma↗
PubMed1997

Immunohistochemical detection of p53 tumor suppressor gene protein in canine epithelial colorectal tumors.

Eighty canine epithelial colorectal tumors obtained by excisional biopsy were evaluated immunohistochemically for p53 tumor suppressor gene protein. Dogs in the study average 6.9 years of age (range, 1-12.5 years). A standard avidin-biotin immunohistochemical protocol incorporated a polyclonal antibody of rabbit origin (CM-1) as the primary antibody. Positive staining was observed within all subcategories of lesions, including hyperplastic polyps 1/2 (50%), adenomas 14/29 (48%), carcinomas in situ 9/22 (41%), adenocarcinomas 3/4 (75%), and invasive carcinomas 8/23 (35%). A total of 35/80 (44%) positive tumors wee identified. Fifteen of 31 (48%) benign tumors labeled for p53 protein compared to 20/49 (41%) malignant tumors. Survival data was available for 57/80 (71%) dogs. The average age of dogs within the group with survival data was 4.4 years. Males predominated 34/57 (60%). Mean survival time was 20.6 months. There was no significant difference in survival time between dogs grouped according to p53 immunoreactivity, cellular stain location, or tumor site. A statistically significant increase in survival time was observed between dogs with clean surgical margins and those without (P < 0.018) and for dogs with adenomas or carcinomas in situ over dogs with invasive carcinomas (P < 0.02). In this study, the overall greater positive staining frequency of benign lesions compared to malignant lesions is contrary to data derived from similar immunohistochemical analyses of human tumors and is incongruous with the theorized late-stage participation of the p53 protein in the development of human colorectal cancers. The results of this study suggest that if the p53 tumor suppressor gene protein is involved in the progression of canine colorectal tumors, it may play a relatively early role, possibly analogous to the early appearance of p53 overexpression in precancerous lesions of human ulcerative colitis. Immunohistochemical detection of p53 was not useful prognostically.

Adenocarcinoma↗
PubMed1992

[Early diagnosis saves human lives--on the status of colorectal tumors].

UNLABELLED: Colorectal cancers are on rang 3 of the malignant tumors in men and in women in incidence as well as in mortality. The only method to save more patients with these tumors is the early detection. It is to realize at its best by combination of digital rectal examination (DRE), testing for blood in feces and sigmoidoscopy. About DRE nothing is to discuss. The lack of a method without a high percentage of false negative and false positive results is the main problem of testing blood in feces. But the existing methods have to be used until more effective ones will be developed. Method no 3 is the sigmoidoscopy with the new generation of flexible instruments. Doctors have to prefer them because their use is easier, more informative and better tolerable for patients as the old rigid rectoscops. An additional method to evaluate the tumor expansion during surgical treatment is the endoscopic ultrasound examination. It enables the surgeon to look through the colorectal wall for evaluation of the tumor-spreading. There is no doubt, that the surgical treatment is the most effective. It can save around 90% of tumor patients if the tumor is detected in an early stage. The results of chemotherapy are not convincing at all. 5-fluorouracil (5-FU) seems to be the most effective but not curing drug, possibly in combination with immunemodulators. IN CONCLUSION: Colorectal cancer, early detection is the key. If the patient, the practicien and the surgeon will have this in mind, 50,000 pats with colorectal cancer more could be saved this year in the USA. Similar results should be possible in our country also.

Colorectal Neoplasms↗
PubMed1997

Tumorigenesis in colorectal tumors from patients with hereditary non-polyposis colorectal cancer.

Tumorigenesis of colorectal cancer in patients with hereditary non-polyposis colorectal cancer (HNPCC) has been postulated to follow a different pathway from that of sporadic colorectal tumors. A characteristic of HNPCC-associated tumors is the replication error phenotype. We studied tumorigenesis in 8 fresh-frozen and 67 paraffin-embedded colorectal tumors derived from 29 families with HNPCC or a familial aggregation of colorectal cancer. By using intragenic markers, inactivation of the wild-type allele of hMLH1 was shown to occur through loss of heterozygosity and not through a somatic point mutation. Microsatellite instability is very common and occurs early in almost all colorectal tumors from HNPCC patients. Transforming growth factor beta type II receptor (T beta RII) mutations occur in these tumors at a high frequency. Of colorectal cancers from families with HNPCC, 63% have frameshift mutations in T beta RII, compared with 10% of sporadic colorectal cancers. APC and K-RAS mutations appear to be as frequent in the HNPCC tumors as in the sporadic counterpart.

Alleles↗