A novel germ-line mutation in the noncoding region of the p53 gene in a Li-Fraumeni family.

We identified a novel germ-line p53 mutation in the noncoding, nonsplicing regions of a Li-Fraumeni family. Patients belonging to this family included pediatric medulloblastoma and rhabdomyosarcoma patients and a breast carcinoma patient. Three positions in the p53 gene were analyzed for loss of heterozygosity (LOH). One of the three loci retained heterozygosity, whereas the other two exhibited LOH. Sequence analysis of the third locus identified a change of 5'-CCGGGTGA-3' to 5'-CCAGGTTGGA-3', 63 bp downstream of exon 6. The mutation was identified in the germ line of the two pediatric patients and in each of the related parents. We excluded any additional mutation in the entire coding region of the p53 gene, including splice-site intronic sequences. Strong positive nuclear staining of the p53 protein was detected in both normal and tumor paraffin-embedded tissues. Eighty-five normal persons were negative for this alteration, which thus supports it as a mutation. These results may indicate that genetic changes within the noncoding region of the p53 gene may serve as an alternative mechanism of activating this gene. Mutations in the noncoding region of this gene should be further studied.

Mutations of the adenomatous polyposis coli and p53 genes in a child with Turcot's syndrome.

Turcot's syndrome is a rare heritable complex that is characterized by an association between a primary neuroepithelial tumor of the central nervous system and multiple colonic polyps. The aim of this study was to analyze genetic alterations in a case of Turcot's syndrome in a 10.5-year-old boy in whom a colorectal tumor developed 3.5 years following astrocytoma. An APC germline non-sense mutation at codon 1284 leading to a truncated protein was identified, as was a somatic p53 mutation in the colorectal carcinoma in exon 7, codon 244. The latter was not identified in the primary astrocytoma. However, immunohistochemistry revealed high p53 protein expression in both tumors, suggesting an additional p53 mutation in the primary astrocytic tumor. The diverse p53 mutations observed in this unique syndrome in two different sites and stages of the disease may shed light on the multistep progression of the malignant events.

A novel germ line p53 mutation in intron 6 in diverse childhood malignancies.

Screening for p53 mutations in exons 5 to 8 in 124 pediatric malignancies identified 18 abnormal shifts using single strand conformation polymorphism: 12 were missense mutations and in 6, no mutation was detected in the exon or in the splice donor acceptor sequences. Sequencing was then performed in the adjacent introns, revealing a G to A base substitution at 39 base pairs upstream to exon 7. This mutation was identified in the germ line of five of the patients, and also in the father of one, whose parents were available. For comparison, of the 184 normal controls similarly screened, only one had this mutation (P=0.036). Positive staining of p53 protein was observed in three of the paraffin embedded tissues that were available: brain tumor, rhabdomyosarcoma, and lymphocytes from a normal lymph node from the rhabdomyosarcoma patient. All tumors with the identified intron mutation were Li-Fraumeni syndrome tumors. Sequencing of all exons including splice sites was performed and revealed no mutation. We suggest that this mutation in intron 6 of the p53 gene stabilizes the wild type p53 protein, resulting in its abnormal accumulation. Mutations in the noncoding region of p53 should be further studied.

Enhanced tumor necrosis factor in anti-CD3 antibody stimulated diabetic NOD mice: modulation by PGE1 and dietary lipid.

Administration of OKT3 anti-CD3 monoclonal antibody (mAb) to patients for transplant rejection, is associated with a distinct and often severe clinical syndrome related to massive cytokine release. Previous reports have similarly demonstrated increased levels of serum tumor necrosis factor alpha (TNF alpha) in normal mice following administration of 1452-C11 anti-CD3 mAb. In this study, we compared serum TNF alpha levels at baseline and after anti-CD3 stimulation among three groups of mice: normal BALB/c controls, pre-diabetic non-obese diabetic (NOD) mice, and diabetic NOD mice. Baseline serum TNF alpha levels, as measured by L929 cell bioassay, were 2xhigher in diabetic NOD and 3xhigher in pre-diabetic NOD compared with BALB/c. Ninety minutes after anti-CD3 mAb stimulation, serum from BALB/c controls and pre-diabetic NOD contained 2- to 8-fold higher levels of TNF-alpha as compared to untreated control mice. In contrast, following anti-CD3 mAb, there was a dramatic 20-fold increase in serum TNF alpha in diabetic NOD mice (levels > 5000 pg/ml). Additionally, anti-CD3 mAb increased the steady-state TNF alpha mRNA transcripts. Spleens from diabetic mice given anti-CD3 mAb had higher steady-state TNF alpha mRNA than spleen from normal mice similarly treated. The enhanced release of circulating TNF alpha after anti-CD3 mAb in diabetic NOD mice was abrogated by pre-treatment of mice with prostaglandin E1 (PGE1) 30 min prior to anti-CD3 mAb stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)