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

PURPOSE: Childhood cancer is closely related to the mutation of tumor suppressor gene. The mutant gene may evoke congenital anomaly and development of cancer. The common solid tumors in childhood are Wilms' tumor, retinoblastoma and neuroblastoma. The cytogenetic study has been performed. The cytogentic study revealed structural abnormality of chromosome in Wilms' tumor and retinoblastoma. The oncogene and mutation of tumor suppressor gene are applicable to the study of carcinogenesis of childhood cancer. We studied to investigate the expression of p53, Rb and WT-1 in Wilms' tumor and retinoblastoma. METHODS: Immunohistochemical study has been performed to investigate the expression of p53, Rb and WT-1 in 7 cases of Wilms' tumor and 4 cases of retinoblastoma of childhood cancer. RESULTS: The positive reaction for p53, Rb and WT-l was seen in the nuclei of tumor cells. The positive reaction for tumor suppressor gene products in Wilms' tumor showed that p53 (mutant type) was 57.1%, Rb 85.7%, WT-l 28.6%. The immunohistochemistry for tumor suppressor gene products in retinoblastoma revealed that p53 protein (mutant type) was seen in all the cases, but Rb and WT-l protein were not seen. CONCLUSION: These results suggested that Wilms' tumor may be partially related with mutation of p53, Rb and WT-1, and retinoblastoma may have a relationship with mutation of p53 and Rb.
Carcinogenesis ; Cytogenetics ; Genes, Tumor Suppressor ; Immunohistochemistry ; Neuroblastoma ; Oncogenes ; Retinoblastoma ; Wilms Tumor

Development of the human colorectal cancer is associated with several distinct genetic abnormalities involving both dominant-acting oncogenes (K-ras, c-src) and tumor suppressor genes (APC, DCC, p53) which undergo inactivation or loss. In colorectal tumors, the common molecular alteration is localized in the 17p13 and 5q21 loci encoding the p53 and the APC gene, respectively. The identification of these genes may help the understanding of the pathogenesis of colorectal neoplasia. In order to determine whether the frequency of the genetic alterations varies with sex, age, tumor size, or site, including pathologic parameters, such as degree of differentiation, tumor stage, mucin component, lymphoid reaction, tumor invasion pattern, vein and nerve invasion, lymph node metastasis, and other parameters, such as disease-free survival, distant metastasis and patient outcome, the authors analyzed the loss of heterozygosity (LOH) of the APC and the p53 genes in paraffin-embedded specimens of 48 colorectal cancers by use of the polymerase chain reaction and restriction fragment length polymorphism. The results were as follows: the LOH affecting the APC was found in 15 out of 31 (48.4%) heterozygous patients, while the LOH of the p53 locus was observed in 11 out of 26 (42.3%) patients. Among 48 patients, the LOH at both the APC and the p53 loci was observed in five (10.4%) patient. No statistically significant associations were found between the LOH of the APC gene and the proposed parameters. The relationship between the LOH of the p53 and the histologic differentiation, lymphoid reaction was significant (P<0.05), but survival was not correlated. Statistically significant associations were found between overall survival of the colorectal cancer patients and distant metastasis, Astler-Coller stage, lymphoid reaction, invasion pattern, nerve invasion, vein invasion, lymph node metastasis, and disease free survival. The above results suggest that the LOH of the p53 genes could be involved in the progression of colorectal cancers. However, neither the LOH of the APC nor that of the p53 have significant association with survival of the colorectal cancer patients.
Colorectal Neoplasms* ; Disease-Free Survival ; Genes, APC ; Genes, p53 ; Genes, Tumor Suppressor* ; Humans ; Loss of Heterozygosity* ; Lymph Nodes ; Mucins ; Neoplasm Metastasis ; Oncogenes ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Veins

OBJECTIVEBoth tumor suppressor p16INK4A and p15INK4B are members of INK family of CDK inhibitor. Although the role of p16 has been well documented, the role of p15 and its signaling pathway remain less well studied. This study was aimed to assess the effect of p16 and p15 on hepatocarcinoma cell lines with different status of Rb gene.

METHODSAfter identification of the genetic status of p16, p15 as well as Rb of human hepatocellular carcinoma (HCC) cell lines BEL7402, SMMC7721 with the use of multiple PCR, the eukaryotic expression p16 and p15 recombinants pXJ-p16 and pXJ-p15 were constructed, respectively. The existence of exogenous p16, p15 genes, and the expression of p16 and p15 were assayed by means of PCR and RNA dot blotting. Finally, the proliferation and apoptosis were studied by using MTT, colony formation assay and flow cytometry.

RESULTSNeither deletion of p16 nor p15 was detected in the two cell lines. However, Rb exons 14-16 instead of exons 22-23 deletion existed in SMMC7721. The increased mRNA expression level of p16 was found in BEL7402-p16 and SMMC7721-p16, while increased mRNA expression level of p15 was found in BEL7402-p15. The endogenous p16 and p15 genes were transcripted at low level. The cell growth and colony formation were decreased in BEL7402-p15, compared with either mock cell BEL7402 or vector control cell BEL7402-pXJ. Also shown in this study were an altered G1 phase population from 37.7% to 43.6%, an S phase population from 22% to 13% (P<0.05), and a Sub G1 peak (apoptosis peak) in BEL7402-p15. Conversely, BEL7402-p16 with endogenous p16 gene showed neither difference in cell cycle population nor difference in colony formation rate, compared with control cell groups. Additionally, SMMC7721-p16 cell growth was not inhibited by exogenous p16 gene.

CONCLUSIONp15 significantly arrested cell proliferation and induced apoptosis in BEL7402 in vitro, and the function was not influenced by endogenous p15 gene. The inhibition of cell growth by p16 on HCC cells could be dependent on intact RB pathway.

Apoptosis ; Carcinoma, Hepatocellular ; genetics ; Cell Cycle Proteins ; genetics ; Cell Division ; Cyclin-Dependent Kinase Inhibitor p15 ; Genes, Retinoblastoma ; Genes, Tumor Suppressor ; Genes, p16 ; Humans ; Liver Neoplasms ; genetics ; pathology ; RNA, Messenger ; analysis ; Tumor Suppressor Proteins ; genetics

OBJECTIVETo detect the loss of heterozygosity (LOH) in esophageal squamous cell carcinoma and adjacent high-grade squamous dysplasia, and to evaluate possible tumor suppressor genes in the development and progression of invasive malignancy.

METHODSLOH was detected in normal esophageal mucosa, high grade squamous dysplasia and esophageal squamous cell carcinoma using microdissection and polymerase chain reaction technology. The changes of LOH at seven microsatellite markers and the relationship between LOH rate and clinicopathologic parameters were analyzed.

RESULTSIn high grade squamous dysplasia, LOH was detected at D13S802 (40%), D13S267 (32%), D13S221 (31%), D9S942 (30%), D17S520 (24%) and D9S171 (33%). However, D17S1798 LOH was not detected. In invasive squamous cell carcinoma, LOH was detected as follows: D13S267 (71%), D13S802 (58%), D17S520 (55%), D13S221 (45%), D9S942 (43%), D9S171 (33%) and D17S1798 (11%). The frequency of LOH in the seven microsatellite markers, the pathologic grade, clinical stage and occurrence of lymph node metastasis did not show any statistically significant correlation (P > 0.05).

CONCLUSIONSThe progression from normal squamous epithelium to high grade squamous dysplasia and subsequently to invasive squamous cell carcinoma of the esophagus was associated with accumulation of genetic errors. Possible tumor suppressor genes related to the development of esophageal squamous cell carcinoma may exist near D13S802 (13q12.12). Possible tumor suppressor genes near D13S267 (13q13.1), D17S1798 (17p13.3) and D17S520 (17p13.1) may be related to the progression of esophageal squamous cell carcinoma.

Adult ; Aged ; Carcinoma, Squamous Cell ; genetics ; Chromosome Mapping ; Chromosomes, Human, Pair 13 ; Chromosomes, Human, Pair 17 ; Chromosomes, Human, Pair 9 ; Esophageal Neoplasms ; genetics ; Female ; Genes, Retinoblastoma ; Genes, Tumor Suppressor ; Genes, p16 ; Genes, p53 ; Humans ; Loss of Heterozygosity ; Male ; Microsatellite Repeats ; Middle Aged ; Precancerous Conditions ; genetics

A large number of data derived from molecular analyses support the hypothesis that human cancer is a genetic disease and a distinct subset of genes have been found to be genetically changed in most tumors. Molecular alterations in pancreatic cancer include: (1) oncogenes such as K-ras, c-myc, c-fos, and c-erbB-2; (2) tumor suppressor genes such as p53, p16, DPC4/SMAD4, and DCC; and (3) growth factors such as EGF, FGF, HGF, PDGF, VEGF, TGF-beta. Genetic alterations of K-ras and p53 are common in human pancreatic cancer, but the occurrence of pancreatic cancer is a multi-step phenomenon in which the accumulation of genetic changes is extremely important.
Epidermal Growth Factor ; genetics ; Fibroblast Growth Factors ; genetics ; Genes, Tumor Suppressor ; Genes, myc ; genetics ; Genes, p16 ; Genes, p53 ; genetics ; Genes, ras ; genetics ; Growth Substances ; genetics ; metabolism ; Humans ; Oncogenes ; genetics ; Pancreatic Neoplasms ; genetics

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

Several molecular and genetic changes have been found in pituitary adenomas. We looked for correlations between these changes and the degree of invasiveness of the tumors. The invasiveness of 11 pituitary adenomas was graded by Hardy classification. We examined the retinoblastoma gene (RB1.20 on chromosome 13q) and the region around the MEN1 locus (chromosome 11q13.1-5) for loss of heterozygosity. Also examined are p53 mutations using single strain conformation polymorphism, p53 protein overexpression using immuno cytochemistry, homozygous deletions of p15 and p16 by polymerase chain reaction, and cellular proliferative activity using MIB-1 antibody. Six tumors (54.5%) had an LOH at either RB1.20 or the MEN1 locus. LOHs were found more frequently in Grade 4 and stage E tumors (72% and 67%) than in Grade 3 and stage D tumors (25% and 40%). However, no mutation or overexpression of p53 was found. No homozygous deletions of p15 or p16 were identified. The cell proliferative index ranged from 0 to 3%. LOH at 11q13 and 13q may be valuable in predicting the invasiveness of pituitary adenomas.
Adenoma/*genetics/*pathology/physiopathology/radiography ; Adult ; Aged ; Aged, 80 and over ; Cell Cycle Proteins/genetics ; Cell Transformation, Neoplastic ; Chromosomes, Human, Pair 11 ; Chromosomes, Human, Pair 13 ; Female ; *Genes, Retinoblastoma ; Genes, Tumor Suppressor ; Genes, p53 ; Human ; Loss of Heterozygosity ; Male ; Middle Age ; Mutation ; Neoplasm Invasiveness ; Neoplasm Proteins/*genetics ; Pituitary Neoplasms/*genetics/*pathology/physiopathology/radiography ; Polymorphism, Single-Stranded Conformational ; Protein p16/genetics ; Protein p53/genetics/metabolism

OBJECTIVES: Recently, the studies for oncogene and tumor marker have been actively performed to investigate the carcinogenesis of gastric carcinoma, but it is not clearly understood. We investigated the expression of tumor suppressor gene and proliferation activity in gastric carcinoma. METHODS: Immunohistochemistry for p53 protein (wild and mutant type), retinoblastoma protein(wild type), and PCNA was performed in 131 cases of formalin fixed paraffin embedded tissue sections of gastric carcinoma. We compared that expression with tissue invasiveness, lymph node metastasis, staging and, Lauren classification, and that expression with each other. RESULTS: 1) The positive ratio of p53 protein, Rb protein, also PCNA in gastric carcinoma was 64.9%, 98.5%, 99.2%, 2) The expression of p53 protein was related to invasiveness, lymph node metastasis, staging, and Lauren classification(p<0.05). 3) The positive reaction for Rb gene was identified in tumor cells as well as proliferating cells. 4) There was a close relationship between Rb gene expression and PCNA in gastric carcinoma (p<0.05). CONCLUSION: Theses results suggested that the expression of p53 gene is related to invasiveness, lymph node metastasis, staging and Lauren classification in gastric carcinoma. Expression of retinoblastoma gene is a closely related to proliferating activity.
Carcinogenesis ; Classification ; Dronabinol* ; Formaldehyde ; Genes, p53 ; Genes, Retinoblastoma ; Genes, Tumor Suppressor ; Immunohistochemistry ; Lymph Nodes ; Neoplasm Metastasis ; Oncogenes ; Paraffin ; Proliferating Cell Nuclear Antigen* ; Retinoblastoma ; Retinoblastoma Protein

OBJECTIVES: The inactivation of the tumor suppressor gene p16INK4a plays an important role in the development of malignant tumors, including oral squamous cell carcinoma. The p16 gene is involved in the p16/cyclin-dependent kinase/retinoblastoma (Rb) gene pathway of cell cycle control. The p16 protein is considered a negative regulator of this pathway. The p16 gene encodes an inhibitor of cyclin-dependent kinases 4 and 6 which regulate the phosphorylation of the retinoblastoma gene and G1 to S phase transition in the cell cycle. However, the p16 gene can lose its functionality through point mutations, loss of heterozygosity or methylation of its promoter region. MATERIALS AND METHODS: In this study, the authors analyzed the correlation between various clinicopathological findings-patient age, gender and smoking, disease recurrence, tumor size, stage, and differentiation- and p16 protein expression or p16 promoter hypermethylation in 59 cases of head and neck squamous cell carcinoma. RESULTS: The results revealed p16 protein expression and p16 promoter hypermethylation in 28 cases (47.5%) and 21 cases (35.6%), respectively, of head and neck squamous cell carcinoma. However, neither p16 protein expression nor p16 promoter hypermethylation had any statistical influence on clinicopathological findings or survival rate. CONCLUSION: This data, and a review of the literature, suggest that p16 promoter hypermethylation cannot yet be used as an independent prognostic factor influencing carcinogenesis, but must be considered as an important factor along with other genetic alterations affecting the pRb pathway.
Carcinoma, Squamous Cell ; Cell Cycle ; Cell Cycle Checkpoints ; Cyclin-Dependent Kinases ; Epigenomics ; Genes, p16 ; Genes, Retinoblastoma ; Genes, Tumor Suppressor ; Head ; Humans ; Loss of Heterozygosity ; Methylation ; Neck ; Phosphorylation ; Point Mutation ; Prognosis ; Recurrence ; S Phase ; Smoke ; Smoking