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Published on: September 20, 2016
Molecular abnormalities of mdm-2 in human sarcomas
C Buesoramos1, Y Yang, T Manshouri
1UNIV TEXAS,MD ANDERSON CANCER CTR,DIV LAB MED,HEMATOPATHOL PROGRAM,HOUSTON,TX 77030. UNIV TEXAS,MD ANDERSON CANCER CTR,DEPT PATHOL,HOUSTON,TX 77030.
Abstract:
MDM-2 is an oncoprotein that seems to function, at least in part, by interacting with the p53 protein and modulating its tumor-suppressing activity. The MDM-2 gene codes for p57, p74, p76, p85, and p90 proteins. Overexpression of only the p90 MDM-2 protein has been reported in sarcomas showing MDM-2 gene amplification. In addition, post-transcriptional mechanisms have been demonstrated to play a role in the expression of MDM-2 proteins. We investigated MDM-2 gene amplification, mRNA and protein levels in various cases of sarcomas. We found MDM-2 gene amplification in 12 (26%) of 46 cases of sarcoma: 11 of 13 cases of liposarcoma and 1 of 6 cases of malignant fibrous histiocytoma. The MDM-2 amplification correlated with the presence of elevated levels of mRNA and protein in the liposarcomas. In sarcomas other than liposarcomas, mRNA was overexpressed in 7 (30%) of 23 cases, without MDM-2 amplification. In 15 (62.5%) of 24 cases of sarcoma and in 1 case of lipoma the MDM-2 protein was overexpressed as shown by Western blot analysis. Interestingly, p57 not p90 was the most commonly overexpressed MDM-2 protein. These data indicate that the molecular abnormalities affecting MDM-2 expression in cases of sarcoma include transcriptional, post-transcriptional, and gene dosage (amplification) mechanisms. Furthermore, our findings suggest that MDM-2 p57 protein may be as important as p90 in the pathogenesis of human sarcomas.
Insights
MDM-2 gene amplification and protein overexpression, particularly p57, are implicated in sarcoma development. These molecular changes involve transcriptional, post-transcriptional, and gene dosage mechanisms, highlighting MDM-2
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- MDM-2 is an oncoprotein that modulates p53 tumor-suppressing activity.
- The MDM-2 gene encodes multiple proteins, including p57 and p90.
- Aberrant MDM-2 expression is linked to sarcoma pathogenesis.
Purpose of the Study:
- To investigate MDM-2 gene amplification, mRNA, and protein levels in sarcomas.
- To determine the role of different MDM-2 protein isoforms in sarcoma development.
- To elucidate the molecular mechanisms underlying MDM-2 dysregulation in sarcomas.
Main Methods:
- Analysis of MDM-2 gene amplification using quantitative PCR or similar techniques.
- Measurement of MDM-2 mRNA levels via RT-PCR or Northern blot.
- Detection of MDM-2 protein expression using Western blot analysis.
Main Results:
- MDM-2 gene amplification was observed in 26% of sarcomas, notably in liposarcomas.
- Amplification correlated with elevated MDM-2 mRNA and protein in liposarcomas.
- MDM-2 p57 protein was the most commonly overexpressed isoform, not p90, in sarcomas.
Conclusions:
- Sarcomas exhibit diverse molecular abnormalities in MDM-2 expression, including gene amplification, transcriptional, and post-transcriptional alterations.
- MDM-2 p57 protein plays a significant role in human sarcoma pathogenesis, potentially equal to p90.
- Understanding these MDM-2 alterations provides insights into sarcoma development and potential therapeutic targets.
