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Suppression of default apoptosis in androgen-dependent cells by testosterone-mediated bcl-2 expression
1Department of Urology, Saitama Medical School, Japan. ohigashi@med.keio.ac.jp
Background:
The significance of apoptosis with regard to the development and progression of androgen-dependent cells has not been clearly understood. In the present study we investigated the expression of the bcl-2 proto-oncogene after androgen deprivation and its role in cell growth in an androgen-dependent cell line.
Methods:
We used SC2G, an androgen-dependent mouse mammary carcinoma cell line cloned from Shionogi carcinoma 115 (SC115). The expression of bcl-2 mRNA and protein in SC2G cells was measured by reverse transcription-polymerase chain reaction and western blotting, respectively. We also investigated the effects of antisense oligodeoxynucleotides (ODN) complementary to strategic sites in the mouse bcl-2 gene in SC2G cells.
Results:
When SC2G cells were cultured in serum-free medium, the number of viable cells was significantly larger among cells with testosterone than those without testosterone after 3 days. Apoptosis was demonstrated in approximately 30% of positive-staining nuclei in SC2G cells cultured in testosterone-free medium. The levels of bcl-2 mRNA and protein in SC2G cells started to decrease after testosterone withdrawal. The cell density of SC2G cells decreased after 4 days culture with antisense ODN when compared with cells cultured in the presence of sense control.
Conclusions:
These data indicate that bcl-2 proto-oncogene inhibits the self-programmed apoptosis of androgen-dependent cells, suggesting the possibility of an antisense therapy for hormone-refractory prostate cancer, which is reported to express high levels of Bcl-2 protein.
Insights
The bcl-2 proto-oncogene inhibits apoptosis in androgen-dependent cells. Antisense therapy targeting bcl-2 may offer a new treatment for hormone-refractory prostate cancer.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- The role of apoptosis in androgen-dependent cell development and progression remains unclear.
- Investigating the bcl-2 proto-oncogene's expression and function in androgen deprivation is crucial.
Purpose of the Study:
- To examine bcl-2 proto-oncogene expression in androgen-dependent cells following androgen deprivation.
- To elucidate the role of bcl-2 in cell growth and apoptosis in an androgen-dependent cell line.
Main Methods:
- Utilized the SC2G mouse mammary carcinoma cell line.
- Measured bcl-2 mRNA and protein levels using RT-PCR and Western blotting.
- Assessed the impact of antisense oligodeoxynucleotides (ODN) targeting the bcl-2 gene.
Main Results:
- Testosterone withdrawal significantly increased apoptosis in SC2G cells (approx. 30% nuclei).
- bcl-2 mRNA and protein levels decreased upon testosterone withdrawal.
- Antisense ODN treatment reduced SC2G cell density, indicating inhibition of cell growth.
Conclusions:
- The bcl-2 proto-oncogene actively suppresses self-programmed apoptosis in androgen-dependent cells.
- Findings suggest potential for antisense therapy targeting bcl-2 in hormone-refractory prostate cancer, which often overexpresses Bcl-2.