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bcl-2, bax, bcl-XL, and bcl-XS expression in normal and neoplastic ovarian tissues
M Marone1, G Scambia, S Mozzetti
1Department of Obstetrics and Gynecology, Catholic University, Rome, Italy.
Abstract:
The bcl-2 family of proteins includes some important regulators of apoptosis. Among these, bcl-2 and bcl-xL prevent cells from entering apoptosis, whereas bax and bcl-xS can induce cell death. Alterations in the control of this process can lead to a decrease in cell death, thus contributing to neoplastic growth. Diminished susceptibility to chemotherapy has also been attributed, in in vitro systems, to alterations in the levels of bcl-2, bax, or bcl-x. We analyzed the expression of bcl-2, bax, bcl-xL, and bcl-xS in normal and neoplastic ovarian tissues by reverse transcriptase-PCR and Western blotting. The RNA and protein levels were significantly correlated for all genes. Interestingly, the levels of these genes in normal and neoplastic tissues were significantly different: bcl-2 was higher in normal tissue (P < 0.002), whereas bax and bcl-xL were higher in carcinoma (P < 0.018 and P < 0.030, respectively). bcl-xS was present at low levels in 83% of neoplastic samples and was undetectable in normal tissue. Reverse transcriptase-PCR analysis of 74 tumors showed no major correlation with clinicopathological parameters or with response to chemotherapy. Only bax and bcl-xL were correlated with progesterone receptor levels (n = 29, r = +0.44, P < 0.0189, and r = -0.40, P < 0.035, respectively). No correlation was found with estrogen receptor levels or with p53 immunostaining. Our data indicate that the regulation of the bcl-2 family of proteins differs between normal and neoplastic ovarian tissues. Moreover, the modulation of these genes in ovarian carcinoma is different compared to other tissues; therefore, tissue specificity is very important in regulation of the bcl-2 family of proteins.
Insights
The bcl-2 family proteins regulate apoptosis. Ovarian cancer shows altered bcl-2, bax, and bcl-xL expression compared to normal tissue, with bcl-xS unique to tumors, indicating tissue-specific regulation.
Area of Science:
- Molecular Biology
- Oncology
- Cell Biology
Background:
- The bcl-2 protein family critically regulates apoptosis (programmed cell death).
- Dysregulation of apoptosis contributes to neoplastic growth and chemotherapy resistance.
- Specific bcl-2 family members (bcl-2, bcl-xL, bax, bcl-xS) have opposing roles in cell death pathways.
Purpose of the Study:
- To investigate the expression patterns of bcl-2 family proteins in normal and neoplastic ovarian tissues.
- To determine correlations between bcl-2 family gene expression and clinicopathological parameters or chemotherapy response in ovarian cancer.
Main Methods:
- Analysis of bcl-2, bax, bcl-xL, and bcl-xS expression using reverse transcriptase-PCR and Western blotting.
- Quantitative assessment of RNA and protein levels in 74 ovarian tumor samples and normal ovarian tissues.
- Correlation analysis with clinicopathological data, including hormone receptor status and p53 immunostaining.
Main Results:
- Significant differences in bcl-2 family gene expression between normal and neoplastic ovarian tissues were observed.
- bcl-2 levels were higher in normal tissue, while bax and bcl-xL were elevated in carcinomas.
- bcl-xS was detected in most tumors but absent in normal tissue; no strong correlation with clinical parameters or chemotherapy response was found.
Conclusions:
- Ovarian tissue exhibits unique regulation of the bcl-2 protein family compared to other tissues.
- Altered expression of bcl-2 family members in ovarian carcinoma suggests their involvement in tumorigenesis.
- Tissue specificity is a crucial factor in the regulatory mechanisms of the bcl-2 family.