(2) Coincidental p53 allele mutation and PML loss shifts the tumor profile toward sarcoma formation, which is paralleled in human leiomyosarcomas (indicated by immunohistochemistry; IHC).
Soft tissue sarcoma (STS) also develops, though less frequently, in burn scars. p53 gene mutations were analyzed in paraffin-embedded specimens from 5 patients with STS (4 males and 1 female) that had arisen in a burn scar, by means of polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by direct sequencing.
Soft tissue sarcoma patients with the Pro/Pro variant had a reduced survival rate (30%), when compared to the p53 Arg/Arg (45%) and the p53 Arg/Pro groups (55%).
Sarcoma physicians (N = 124) from 21 countries participated, 40% of whom favored TP53 mutation testing in children regardless of family history, increasing to ∼83% for all age groups if a family history was present and ∼85% if multiple primary cancers were present.
A high proliferative index was demonstrated in 27.5% (11/40) of the tumours (2 MFH, 4 leiomyosarcomas, 1 rhabdomyosarcoma, 1 osteosarcoma, 2 Ewing's sarcomas and 1 unclassified sarcoma). p53 overexpression was associated with high tumour grade (p < 0.05) and MIB-1 expression was correlated with reduced survival (p < 0.05), but p53 overexpression was not significantly associated with either MIB-1 score or with overall survival of the patients.
A high proportion (58%) of the radiation-induced sarcomas exhibited a somatic inactivating mutation for one allele of TP53, systematically associated with a loss of the other allele.
A high proportion (58%) of the radiation-induced sarcomas exhibited a somatic inactivating mutation for one allele of TP53, systematically associated with a loss of the other allele.
A tumorigenic connection between the oncogene product Mdm2 and tumor suppressor p53 is generally accepted, but their possible clinical relevance has not yet been investigated sufficiently in soft tissue sarcoma.
Abnormalities identified by immunohistochemistry included p21 immunonegativity (60%, 25%, 93%), which was most frequent in TE-GBM (P = .008), strong nuclear p53 staining (29%, 29%, 41%), strong membranous staining for epidermal growth factor receptor (EGFR) (21%, 63%, 19%), which was most frequent in E-GBM (P = .03), and an increased frequency of p27 immunonegativity in gliosarcomas (15% negative, 85% focal) compared with tumors without sarcoma (38% strongly positive) (P = .009).
Abnormalities of the p53 gene were found in several classes of soft tissue sarcoma, including leiomyosarcomas, rhabdomyosarcomas and malignant fibrous histiocytomas.
Accelerated carcinoma and sarcoma tumour formation in p53(+/-) females with bi-allelic Igf2 expression was associated with reductions in p53 loss of heterozygosity and apoptosis.
Although neither of these two genes have been previously associated with sarcoma, ABCB5 has been shown to share clinical drug resistance associations with melanoma and leukaemia and C16orf96 shares regulatory elements with genes that are involved with TNF-alpha mediated apoptosis in a p53/TP53-dependent manner.
Among genes governing the apoptosis pathway, overexpression of the bcl2 family or mutations of p53 have recently been reported to be involved in drug resistance in sarcoma.
Amplification of the MDM2 gene, which maps to chromosome band 12q13 and encodes a p53-binding protein, may result in functional inactivation of p53 and has been observed in various bone and soft tissue sarcomas.