| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
To investigate which of paternal or maternal allele is related to the loss of heterozygosity (LOH) of chromosome 17p that is frequently observed in human glioblastomas, we analyzed restriction fragment length polymorphism (RFLP) of genomic DNA derived from tumor and peripheral blood leukocytes in young adults and children with glial tumor.
So far, we have collected 15 cases in which genomic DNA was extracted from the tumor, patient leukocytes, and parents' leukocytes.In these 15 cases, however, we have not found a case which shows LOH of chromosome 17p in patient's leukocyte-derived DNA as compared to the parental DNA.As an explanation for this, it is considered that LOH of p53 gene on chromosome 17p occurs in glioma-oncogenesis but not in germ-line, contrasting to the WT1 gene.However, this supposition remained to be confirmed, since RFLP analysis can miss a minute change of genomic DNA adjacent to the TP53 gene, because of the limitations in informativeness of fragment length by a limited number of restriction enzyme digestion.Also it is possible that recombination of chromosomal genes in meiosis can mas the LOH.To solve this problem, we employed a new assay of mutant p53 using yeast two-hybrid system to detect abnormality of p53 gene at both mRNA and genomic DNA levels.This assay can quantify them mutation of p53 gene as loss of the transcriptional activity by in vivo expression of p53 and reporter plasmid construct of ADE2 gene.So far, we have found 4 tumors with p53 gene mutation in young patients (below 30 year-old), but these mutations have not been reproduced in the leukocyte-derived genomic DNA.In conclusion, p53 gene mutation is considered to occur primarily in the glioma cells but not in parental germ-line, except for special cases of Li-Fraumeni syndrome.
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