Relationship between exon deletion frequency of CDKN2/P16 and pathological type,metastasis,sex in osteosarcoma / 中国组织工程研究

Objective To study on the CDKN2/P16 gene in primary osteosarcoma.Method By using molecular biological methods that inclued genome DNA extraction from paraffined tissue and PCR SSCP analysis technique, we studied alternations of CDKN2/P16 gene in 25 primary osteosarcomas.Results (1)The deletions frequency in differentiation degree of osteosarcomas was① bone brood cell, 16.7% ;② cartilage brood cell,12.5% ;③ Fiber brood cell:20% ,(P >0.05).(2)The deletion frequency in male patients was 17.6% , female patients 12.5% ,(P >0.05).(3)In early metastatic osteosarcomas the deletion rate was 33.3% ,which was significantly higher than that of the control group with the rate of 10.5% (P< 0.05).(4)The deletion rate was 16% and the mutations were not found.Conclusion (1)The deletion rate was 16% and the mutations were not found.This suggests that the deletions of CDKN2/P16 gene were closely related to the genesis of primary osteosarcoma and that the main type of the alternation of CDKN2/P16 gene was deletion.(2)In early metastatic osteosaarcomas the deletion rate was 33.3% , which was significantly higher than that of the control group with the rate of 10.5% .This indicates to great extend that the deletions of CDKN2/P16 gene were closely related to the metastatic ability.(3)The deletions frequency had no significant relationship with differentiation degree of osteosarcomas, so was with the sex of the patient.

The Study of CDKN2/p16INK4A Mutation in Human Breast Cancer

The p16 is a cyclin-dependent kinase inhibitor(CDKI) that inhibits cell cycle progression. In recent studies, homozygous deletions of p16 gene have been noted in some cancer cell lines, which implies the deletion or mutation of p16 gene may contribute to the malignant progression of cells in some ways. This study was to investigate the frequency of p16 gene mutation in breast cancer patients by using polymerase chain reaction-single stranded confromational polymorphysm(PCR-SSCP) analysis. Examination of 24 blood samples and corresponding 16 tissue samples from 24 breast cancer patients were performed by PCR-SSCP method. Four from 24 blood samples(16.7%) disclosed 3 abnormal bands and one band shifting. Among 13 tissue samples revealed three conformational changes(23.1%). In two cases, there were abnormal bands in both blood samples and cancer tissues. One case with no products by PCR in the tissue sample showed a band shifting in the blood sample. Three cases with no PCR products in tissue samples may considered as total allelic deletion of the p16. The cases of abnormal PCR-SSCP results show some abnormalities on direct sequencing by Sanger method as T base insertion, C/T and A/G bases substitution. The results may suggest some of breast cancer patients have germline mutations of the p16 gene and some have somatic mutations. In the carcinogenesis of some breast cancers, p16 gene mutation may dysregulates the cell cycle, that may play an important role in the unlimited tumor cell proliferations.

Altered Expressions and Point Mutations of p53 in Human Bladder Transitional Cell Carcinomas / 대한비뇨기과학회지

The objective of this study was to characterise the pattern of p53 mutations in bladder tumor. In this study, 25 bladder transitional cell carcinomas were analyzed by immunohisochemistry (IHC) for p53 nuclear overexpression, and the results were compared with those of polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis in exon 5-8 of the p53 gene and DNA sequencing analysis. 15 out of 20 cases (75%) showed p53 nuclear immunoreactivities on IHC. On PCR-SSCP analysis, 10 out of 25 cases (40%) had abnormal shifts in mobility. 62% of the mutations were in exon 8. Direct DNA sequencing analysis were performed in these 10 cases to confirm the presence of mutated p53 genes and to determine the type of mutations. Sixteen point mutations were detected in 10 cases. Two specimens had double mutations and another two had triple mutations. G:C-->A:T transitions were the most frequent patterns (62.5%). One mutation was a premature stop codon and two were silent mutations. Three out of 10 had a point mutation at codon 285 (GAG/Glu-->AAG/Lys) and two had at codon 280 (AGA/Arg-->AAA/Lys). One of 16 mutations was transition at hot spot codon 273 with CpG site. These results suggest that altered expressions and point mutations of p53 occured in all grade of bladder cancer, but are more associated with high grade bladder tumors. To elucidate the carcinogenesis of bladder cancer, further studies should be carried out.