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N-(4-hydroxyphenyl) retinamide induces cell cycle specific growth inhibition in PC3 cells
M Igawa1, T Tanabe, G W Chodak
1Department of Surgery, University of Chicago, Illinois.
Abstract:
The synthetic retinoid N-(4-hydroxyphenyl) retinamide (4-HPR) has been demonstrated to inhibit the development of primary and metastatic neoplasms in several animal models. In order to investigate the effect of 4-HPR on human prostate adenocarcinoma, we designed a series of in vitro experiments with the PC3 cell line to evaluate effects on proliferation, cell cycle kinetics, and c-myc mRNA expression. 4-HPR demonstrated cytotoxicity only at the supraphysiologic concentration of 10.0 microM. However, asynchronously growing cells exposed to 1 microM 4-HPR demonstrated a 51% reduction in proliferation rate, associated with an accumulation of cells in the G0/G1 phase of the cell cycle. PC3 cells synchronized with serum deprivation or aphidicolin exhibited significant decreases in DNA synthesis when treated with 1 microM 4-HPR. Additionally, these cells were found to accumulate in G0/G1 and S phase. Northern blots indicated a significant decrease in c-myc mRNA expression in asynchronously growing cells with continuous administration of 1 microM 4-HPR for 6 days. These data suggest that 4-HPR can inhibit growth of PC3 cells as a consequence of a block in cell cycle transition from G1 to S phase at a concentration of 1 microM, and that this inhibition is associated with a suppression of c-myc gene expression.
Insights
The synthetic retinoid N-(4-hydroxyphenyl) retinamide (4-HPR) inhibits human prostate cancer cell growth by blocking cell cycle progression and reducing c-myc gene expression. This study highlights 4-HPR
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Synthetic retinoids show promise in cancer treatment.
- N-(4-hydroxyphenyl) retinamide (4-HPR) has demonstrated anti-neoplastic effects in animal models.
- Prostate adenocarcinoma is a significant health concern requiring novel therapeutic strategies.
Purpose of the Study:
- To investigate the in vitro effects of 4-HPR on human prostate adenocarcinoma PC3 cells.
- To evaluate the impact of 4-HPR on cell proliferation, cell cycle kinetics, and c-myc mRNA expression.
- To determine the effective concentration of 4-HPR for inhibiting prostate cancer cell growth.
Main Methods:
- In vitro experiments using the PC3 cell line.
- Assessment of cell proliferation rates.
- Cell cycle analysis using flow cytometry.
- Quantification of c-myc mRNA expression via Northern blot.
Main Results:
- 1 microM 4-HPR significantly reduced PC3 cell proliferation by 51%.
- 4-HPR induced cell cycle arrest at the G0/G1 and S phases.
- Continuous 4-HPR treatment suppressed c-myc mRNA expression.
- Cytotoxicity was observed only at a high concentration (10.0 microM).
Conclusions:
- 4-HPR inhibits human prostate adenocarcinoma PC3 cell growth at a concentration of 1 microM.
- The anti-proliferative effect is mediated by a block in G1 to S phase cell cycle transition.
- Suppression of c-myc gene expression is associated with 4-HPR-induced growth inhibition.