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[Roles of tumor suppressor genes in human osteosarcoma cells]
1Department of Oral Microbiology, Faculty of Dentistry, Tokyo Medical and Dental University.
Abstract:
Inactivation of two tumor suppressor genes, RB and p53, is associated with tumor formation. To elucidate the molecular basis of the tumorigenesis of human osteosarcoma, structural and expressional alterations of these two genes were examined in five human osteosarcoma cell lines, two of which were from Japanese patients. In addition, I analyzed two adenovirus E1A-binding proteins, p107 and p300, putative "tumor suppressor gene products", which share similar properties with the RB protein in binding to the E1A oncoprotein. Detailed analyses of DNA, mRNA, and protein showed that (1) 3 lines including both Japanese lines lost the expression of the RB protein due to either the absence or the alteration of mRNA caused by DNA rearrangement, (2) abnormality of p53 gene was detected in all cell lines : 4 lines lost p53 expression due to either gene loss or the absence of mRNA, and one line expressed an abnormal form of the protein without detectable DNA and mRNA alterations and (3) no significant alteration of p107 or p300 was detected in all cell lines. These results further confirm that inactivating mutations of p53 and RB genes are deeply involved in the carcinogenesis of human osteosarcoma and suggest that p107 and p300 may not play a role in the tumorigenesis.
Insights
RB and p53 tumor suppressor gene inactivation drives human osteosarcoma formation. Alterations in these genes, but not p107 or p300, were observed in osteosarcoma cell lines, confirming their critical role.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Context:
- Human osteosarcoma is a significant bone cancer.
- Tumor suppressor genes RB and p53 are crucial in preventing cancer.
- Understanding their role in osteosarcoma is vital for treatment.
Purpose:
- To investigate the structural and expressional alterations of RB and p53 genes in human osteosarcoma cell lines.
- To analyze the involvement of adenovirus E1A-binding proteins p107 and p300 in osteosarcoma tumorigenesis.
Summary:
- RB protein expression was lost in 3 cell lines due to mRNA alterations or absence from DNA rearrangement.
- p53 gene abnormalities were found in all cell lines, with 4 losing expression and one expressing an abnormal protein.
- No significant alterations were detected in p107 or p300 genes across all cell lines.
Impact:
- These findings confirm the critical role of p53 and RB gene inactivation in human osteosarcoma development.
- The study suggests that p107 and p300 proteins may not be significantly involved in osteosarcoma tumorigenesis.