PURPOSE: The germline, or somatic, inactivation of tumor suppressor genes, through point mutation, or deletion, plays an important role in carcinogenesis. Several gene alterations, such as adenomatous polyposis coli (APC), deleted in colorectal cancer (DCC) and p53, have been detected in the development of colorectal cancer. Within these genes, a loss of heterozygosity (LOH) at the DCC gene locus was frequently associated with colorectal tumors, and the LOH of the DCC gene, and the expression of the DCC protein, might be related to malignant formation and metastasis. The aim of this study was to determine the DCC LOH and the expression of DCC protein in colorectal cancers, and evaluate their prognostic value and relationship with the clinicopathological data. MTHODE: Fifty colorectal cancer tissues were obtained from resected specimens. Using formalin-fixed paraffin- embedded sections as a source of DNA, we examined the DCC protein in the tissue through immunohistochemical stainings and immunoblotting analysis, the DCC LOH through a polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP). RESULTS: DCC LOH was observed in 24 of the 50 patients (48.0%). The expression of the DCC protein was decreased in the cancer tissue (62.3 23.6%) compared with the adjacent normal mucosa inform the immunoblotting analysis. A decreased DCC protein expression was also observed from the immunohistochemistry, which coincided with the immunoblotting analysis. However, both the DCC LOH and the decreased DCC protein were not related to the clinical and pathological parameters, such as location of tumor, tumor size, histological type and the venous, and lymphatic invasions. There were significant correlations between the DCC protein expression and tumor progression, and hematogenous metastasis (P<.05). CONCLUSIONS: A decreased expression of the DCC protein was noted in human colorectal cancers, and there was a significant relationship between the expression of the DCC protein and distant metastasis, but there was no correlation between the DCC LOH and distant metastasis. These results suggest that the expression of the DCC protein might be related to tumor progression and metastatic potential, and the DCC protein immunoreactivity may be a useful prognostic factor in patients with colorectal cancers.
Adenomatous Polyposis Coli ; Carcinogenesis ; Colorectal Neoplasms* ; DNA ; Genes, DCC* ; Genes, Tumor Suppressor ; Genes, vif ; Humans ; Immunoblotting ; Immunohistochemistry ; Loss of Heterozygosity ; Mucous Membrane ; Neoplasm Metastasis ; Point Mutation ; Polymerase Chain Reaction

Colorectal cancer is one of the malignant tumours of which molecular genetic alterations have been much unveiled among the human cancers. In the multi-stepwise process to the carcinogenesis, it has been recently revealed that the neoplastic growth is originated either from the activiation of oncogene through its mutation, rearragement and amplification, or from the inactivation of the tumour suppression gene through its mutation and deletion. DCC(Deleted in colon cancer) protein is the product of DCC gene, the representative of tumor suppressor genes. The alteration of DCC protein may be related with the aggressiveness of carcinoma and metastasis. As a result, the prognosis of the cancer may be also thought to be affected. Now the prognosis of colorectal cancer mainly depends on pathologic staging, but there are some variations of survival and recurrence among the patients in same stage. Then this study is aimed to reveal the significance of alteration of DCC protein as an independent factor related to prognosis. Twenty three cancer tissues were obtained from the rejected specimens of colorectal carcinomas. We exacted the DCC gene products in the cancer tissues by the methods of immunohistochemical stains and Western blots. We also analyzed the relationships between the alteration of DCC proteins and the status of regional lymph node metastasis or the serum levels of CEA's(carcinoembryonic antigen). As results, we found the abscence or very scanty stains of DCC protein by Western lot in 14 cancer tissues of available 19 cases, but there were all negative responses in immunohistochemical stains. In contrast with above results, there were all positively stains of DCC proteins in corresponding 23 normal colorectal tissues by both the methods. There was no significantly statistical relation between the alteration of DCC proteins and the status of regional lymph node metastasis or the serum level of CEA. In conclusion, we can confirm that the DCC proteins are abscent or very scanty in colorectal cancer tissues and that may be related with the process of carcinogenesis. But the role of DCC protein loss as an independent prognostic factor was not found in this study.
Blotting, Western ; Carcinogenesis ; Colon ; Colorectal Neoplasms* ; Coloring Agents ; Genes, DCC ; Genes, Tumor Suppressor ; Humans ; Lymph Nodes ; Molecular Biology ; Neoplasm Metastasis ; Oncogenes ; Prognosis ; Recurrence ; Staphylococcal Protein A

OBJECTIVETo investigate the role of loss of heterozygosity (LOH) in tumor suppressor genes (TSG) and microsatellite instability (MSI) in hepatocarcinogenesis, as well as their correlation with clinicopathologic features.

METHODSLOH in 6 TSG (APC, DCC, MCC, OGG1, p53 and RB1) was detected in 36 informative cases of hepatocellular carcinoma (HCC), among 92 surgically resected HCC. Thirteen polymorphic microsatellite markers were also studied in 15 of these cases by microdissection-based PCR amplification and direct DNA sequencing. The correlation between genetic alterations and clinicopathologic features was analyzed.

RESULTSThe overall incidence of LOH in HCC was 41.7% (15/36). There was no LOH in MCC gene. 46.2% (6/13) microsatellites showed LOH in 9 of the 15 cases of HCC (60%). Certain clinicopathologic differences were observed between cases (number = 7) with LOH in APC, OGG1 and DCC ("type I") and cases (number = 8) with LOH in p53 and RB1 ("type II"). The mean tumor size of these two types was 2.9 (+/- 1.7) cm and 7.2 (+/- 3.4) cm, respectively (P < 0.01); and the mean survival was 72.0 (+/- 38.6) months, and 51.0 (+/- 30.4) months, respectively (P < 0.05).

CONCLUSIONSCompared with MSI pathway, LOH pathway plays a more important role in the development of HCC. A multistep hepatocarcinogenesis is likely, with LOH in APC, OGG1 and DCC ("type I") being an early event and LOH in p53 and RB1 ("type II") being a late event. On the other hand, MCC gene seems to play no role in the whole process.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Hepatocellular ; genetics ; pathology ; Female ; Genes, APC ; Genes, DCC ; Genes, MCC ; Genes, Tumor Suppressor ; Genes, p53 ; Humans ; Infant ; Liver Neoplasms ; genetics ; pathology ; Loss of Heterozygosity ; Male ; Microsatellite Instability ; Middle Aged

OBJECTIVE: This study aimed to detect the presence of microsatellite (MSI) and loss of heterozygosity (LOH) of the Deleted in Colorectal Cancer (DCC) gene in normal and tumor tissues of Filipino colorectal cancer patients and examine its correlation with age, gender, tumor grade, tumor stage and site of lesion.
METHODS: Paired frozen normal and tumor tissues from thirtynine (39) patients with colorectal adenocarcinoma were used by polymerase chain reaction (PCR). Single strand conformation polymorphism - polyacrylamide gel electrophoresis (SSCP - PAGE) was used to determine MSI and restriction fragment length polymorphism (RFLP) was used to study LOH.
RESULTS: Based on our data, out of the 39 patients, 10 showed LOH of the DCC gene using the LOH markers VNTR, M2 and M3, while no MSI was detected in the samples using the MSI markers BAT25 and BAT26. Correlation with clinicopathological characteristics showed that there is significance for the site of lesion. The LOH has correclation with tumor samples from the colon but not with those from the rectum.
CONCLUSION: Preliminary screening for MSI and LOH of the DCC gene shows that occurrences of colorectal cancer among Filipino patients can be correlated with LOH of the DCC gene with colorectal cancer in a Filipino sample population.

Human ; Male ; Female ; Aged 80 And Over ; Aged ; Middle Aged ; Adult ; Genes, Dcc ; Polymorphism, Single-stranded Conformational ; Colorectal Neoplasms ; Adenocarcinoma ; Loss Of Heterozygosity

Chromosome 18q alteration plays a key role in colorectal tumorigenesis, and loss of heterozygosity at 18q is associated with a poor prognosis in colon cancer. DCC(Deleted in Colorectal Cancer) is a putative tumor- suppressor gene at 18q21 that encodes a transmembrane protein with structural similarity to neural cell adhesion molecule that is involved in both epithelial and neuronal cell differentiation. DCC is implicated in regulation of cell growth, survival and proliferation. Thus, tumor progression in squamous cell carcinoma, stomach cancer, colorectal cancer correlates with downregulation of DCC expression. The mechanism for DCC suppression is associated with hypermethylation of the DCC gene promoter region. Hence, the goal of this study is to identify the promoter methylation responsible for the down-regulation of DCC expression in oral squamous cell carcinoma. 12 of tissue specimens for the study are excised and gathered from 12 patients who are diagnosed as SCC in department of OMS, dental hospital, dankook university. To find expression of DCC in each tissue samples, immunohistochemical staining, RT-PCR gene analysis and methylation specific PCR are processed. The results are as follows. 1. In the DCC gene RT-PCR analysis, 5(41.6%) of 12 specimens of oral squamous cell carcinoma did not expressed DCC gene. 2. In the promoter methylation specific PCR analysis, 5(41.6%) of 12 specimens showed promoter methylation of DCC gene. 3. In the immunohistochemical staining of poor differentiated and invasive oral squamous cell carcinoma, loss of DCC expression was observed. These findings suggest that methylation of the DCC gene may play a role in loss of gene expression in invasive oral squamous cell carcinoma.
Carcinoma, Squamous Cell ; Cell Differentiation ; Cell Transformation, Neoplastic ; Colonic Neoplasms ; Colorectal Neoplasms ; Down-Regulation ; Gene Expression ; Genes, DCC ; Genes, Suppressor ; Humans ; Loss of Heterozygosity ; Methylation ; Neural Cell Adhesion Molecules ; Neurons ; Polymerase Chain Reaction ; Prognosis ; Promoter Regions, Genetic ; Stomach Neoplasms