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Inhibition of endometrial cancer cell lines by mifepristone (RU 486)
C C Schneider1, R K Gibb, D D Taylor
1Department of Obstetrics and Gynecology, University of Louisville School of Medicine, Kentucky 40202, USA.
Objective:
To determine the role of mifepristone (RU 486) in the growth of endometrial cancer cell lines, and the mechanism associated with this regulation.
Methods:
Three endometrial cancer cell lines (Hec-1A, KLE, and RL95-2) were used in this study. Growth inhibition was demonstrated by sulforhodamine B cytotoxicity assay. Mode of inhibition by RU 486 was studied by induction of DNA fragmentation. The effect of RU 486 on steady-state accumulation of the progesterone and glucocorticoid receptors (PRs and GRs, respectively) and apoptosis-associated gene products was studied by Western blotting.
Results:
We demonstrated a dose-dependent inhibition of growth in all of the three endometrial cancer cell lines. Following treatment with 5.0 micrograms/mL of RU 486, there was 39.3%, 66.3%, and 75.5% inhibition of KLE, Hec-1A, and RL95-2 cells, respectively. Decreased expression of GR in RL95-2 (0.1-10 micrograms/mL) and in KLE cells (10 micrograms/mL) was observed. A marked decrease of PR was seen with RL95-2 cells at 10 micrograms/mL, there was no change in the KLE cells, and a dose-dependent decrease was seen with Hec-1A cells. Various levels of apoptosis were demonstrated by DNA fragmentation in all three cell lines. Of the genes associated with apoptosis, dose-dependent reduction of bax expression was demonstrated in KLE cells, while induction of WAF-1 was seen in Hec-1A and RL95-2 cells, and reduction of bcl-2 was demonstrated in RL95-2 cells.
Conclusion:
Clinically achievable doses of RU 486 inhibit endometrial cancer cell lines. The mechanism of inhibition involves apoptosis, and regulation of bax, bcl-2, and WAF-1 is demonstrated. Therapeutic application of these findings remains to be determined.
Insights
Mifepristone (RU 486) effectively inhibits endometrial cancer cell growth by inducing apoptosis. This mechanism involves regulating key genes like bax, bcl-2, and WAF-1, suggesting potential therapeutic applications.
Area of Science:
- Gynecology
- Oncology
- Pharmacology
Background:
- Endometrial cancer is a significant gynecological malignancy.
- Understanding the molecular mechanisms of cancer growth is crucial for developing targeted therapies.
- Mifepristone (RU 486) is a known antiprogestogen and antiglucocorticoid.
Purpose of the Study:
- To investigate the effect of mifepristone (RU 486) on endometrial cancer cell line proliferation.
- To elucidate the underlying molecular mechanisms of RU 486-mediated growth inhibition.
Main Methods:
- Utilized three human endometrial cancer cell lines (Hec-1A, KLE, RL95-2).
- Assessed cell growth inhibition using the sulforhodamine B cytotoxicity assay.
- Investigated apoptosis induction via DNA fragmentation assays.
- Analyzed receptor expression (PR, GR) and apoptosis-related gene products (bax, bcl-2, WAF-1) using Western blotting.
Main Results:
- RU 486 demonstrated dose-dependent growth inhibition across all tested endometrial cancer cell lines.
- Significant growth inhibition percentages were observed: 39.3% (KLE), 66.3% (Hec-1A), and 75.5% (RL95-2) at 5.0 µg/mL.
- RU 486 modulated the expression of progesterone receptors (PR) and glucocorticoid receptors (GR) and induced apoptosis, evidenced by DNA fragmentation.
- Differential regulation of apoptosis-associated genes (bax, bcl-2, WAF-1) was observed among the cell lines.
Conclusions:
- Clinically achievable doses of mifepristone (RU 486) inhibit endometrial cancer cell lines.
- The mechanism of action involves the induction of apoptosis and modulation of bax, bcl-2, and WAF-1 gene expression.
- Further research is warranted to determine the therapeutic potential of RU 486 in endometrial cancer treatment.