PubMed · 2614757
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1989. [Bone sarcomas].. https://pubmed.ncbi.nlm.nih.gov/2614757/
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Alterations in the normal cell cycle lead to abnormal cell proliferation and to tumor development. To explore the role of the cyclin D/Cdk4 complex and the retinoblastoma protein (pRb) in the growth and spread of osteoblastic osteosarcoma (OS), 40 tumor samples were selected. In 17 of these cases, lung metastases occurred during follow-up. Expression of pRb, cyclin D1 and its catalytic subunit, Cdk4, was studied by immunohistochemistry and immunoblotting. As controls, non-neoplastic tissues surrounding the tumor were used. The expression level and pattern were compared to clinical outcome. Cdk4 was over-expressed in 80% of OS, independently of clinical outcome, and showed an intense and uniform distribution in tumor cells compared to normal cells. However, co-immunoprecipitation of Cdk4 with cyclin D1 revealed low levels of cyclin D/Cdk4 complex; 20 of 40 OS examined had a negative or minimal immunostaining for active pRb. The probability of relapse was significantly higher in pRb-negative than in the -positive patients (p < 0.05). The ratio of unphosphorylated/hyperphosphorylated pRb was lower in relapsed patients than in patients with no evident disease, though the difference was not statistically significant. High levels of pRb/cyclin D1 were found in all samples exhibiting functional pRb expression. Our results show that G1 phase deregulation is involved in formation and development of OS. The expression levels of both pRb and cyclin D1 had a clear correlation with clinical outcome, suggesting that these parameters could be used as prognostic markers.
Recent data suggest that deletion of p16INK4 and mutation of TP53 are among the most common genetic events in the development of human cancer, since the codified proteins act as brakes of the abnormal cell cycle. As the molecular events leading to the development of pediatric bone sarcomas remain unclear, we analyzed 75 osteosarcoma and Ewing sarcoma samples from 43 pediatric patients to search for alterations at the TP53 or p16INK4 tumor suppressor genes. By means of PCR-DGGE (polymerase chain reaction and denaturing gradient gel electrophoresis) we detected TP53 point mutations in 18.6% of the tumor samples, but no constitutional mutations. In the analysis of p16INK4, 7% of the samples harbored deletions of the gene but no point mutations were detected by SSCP (single strand conformation polymorphism) analysis, just the polymorphism Ala-->Thr at codon 148. These data support the hypothesis that TP53 alterations may play a role in the development of pediatric bone tumors and that the primary mechanism of inactivation of p16INK4 seems to be homozygous deletion rather than point mutation.
We report on a Japanese girl with multiple cranial hyperostoses and a cardiac tumor, both of which manifested in early childhood. Unique juxtasutural lesions characterized the cranial findings, including a chain of almost symmetrical osseous protuberances involving the frontozygomatic and frontoparietal junctions, and discrete bony bumps on the right occipitoparietal junction and left temporo-occipital junction. These lesions histologically consisted of thickened mature bone intervened with sparse fibrous tissues, mimicking osteoma. The cardiac mass remained pathologically unknown, but was shown to have fatty elements on magnetic resonance imaging (MRI). The patient showed no evidence of gnathic hyperostoses, ophthalmological abnormalities, skin lesions, or other visceral abnormalities, which ultimately precluded known hamartomatous syndromes with craniofacial hyperostoses, such as Gardner and Proteus syndromes. Yet regional Proteus syndrome could not be completely excluded. The craniofacial deformity as a sequel of hyperostoses in our patient superficially resembled that of X-linked calvarial hyperostosis; however, the vacuolated histiocytes that characterized the hyperostotic lesions were not found in our patient. The present disorder may represent a hitherto unknown hamartomatous syndrome.