The converse experiment, in which in vitro-translated E1b 58-kDa protein was mixed with lysates of osteosarcoma cells, showed little or no p53-E1b 58-kDa protein association, even though the in vitro E1b 58-kDa protein could associate stably with p53 from cells containing endogenous p53-E1b 58-kDa protein complex.
In contrast to osteosarcoma Saos-2 cells, expression of wild-type or mutant p53 protein in A673 cells had no effect on morphology or growth characteristics.
Recent developments of importance include an improved understanding of the importance of the p53 gene in the pathogenesis of osteosarcoma, the description of preclinical models, the development of improved imaging techniques for determining tumor extent and responsiveness to chemotherapy, and refinements in therapy.
We analyzed 14 native osteosarcoma tissue samples for alterations of the tumor suppressor genes RB1 and p53 on the DNA level, and as far as possible, the RNA level.
This result suggests that, in addition to the RB (retinoblastoma) gene on 13q and the p53 gene on 17p, at least two more tumor suppressor genes located on 3q and 18q are frequently involved in the development of osteosarcoma.
If both RB1 and TP53 are involved in the initiation of osteosarcoma, the mechanisms for development of the retinoblastoma and osteosarcoma tumors are different.
The immunoelectron-microscopic observation that p53 protein was localized in euchromatic areas of nuclei of osteosarcoma cells supported the specificity of immunoreaction for p53 protein, indicating an active role of p53 protein in the regulation of DNA synthesis and transcription.
The ability of PAb248 to recognise human p53 was established by analysis of the human osteosarcoma derived Saos-2 cell line, which lacks the p53 gene, before and after transfection with p53 cDNA, using western blotting and immunoprecipitation.
Genomic DNA extracted from peripheral-blood leukocytes from 235 unselected children with osteosarcoma from 33 institutions were screened for the presence of germline p53 mutations using constant denaturant gel electrophoresis (CDGE).
Characterization of two tumor suppressor genes, p53 and RB1, that have been implicated in osteosarcoma formation indicated that p53 was altered in five of six osteosarcoma cell lines, whereas RB1 was altered in only two or six of these cell lines.
We demonstrated a germline p53 replication error in two generations of a Li-Fraumeni family affected with liposarcoma, adrenocortical carcinoma, and osteosarcoma.
In contrast, although either functional RB or p53 re-expression effectively suppressed tumor formation in nude mice of the RB-/p53null osteosarcoma cell line, Saos-2, replacement of the wild-type p53 gene had much less impact on their invasiveness as compared to the RB gene.
Contrast study with DNA flow cytometry made on osteosarcoma showed that most of the tumors with strongly positive P53 have higher DNA content than those of negative ones.
Exogenously introduced wild-type and mutant p53 have recently been reported to enhance the human epidermal growth factor receptor (EGF-R) gene promoter activity in p53-deficient Saos2 osteosarcoma cells.
In this study, we tested the oligomerization of p53 with mutations in the oligomerization domain, when expressed in a human osteosarcoma cell line, Saos-2, in vivo.