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Retinoids cause apoptosis in pancreatic cancer cells via activation of RAR-gamma and altered expression of Bcl-2/Bax.

Pettersson F, Dalgleish AG, Bissonnette RP, Colston KW - Br. J. Cancer (2002)

Bottom Line: Only pan-retinoic acid receptor and retinoic acid receptor-gamma selective agonists reduced viability and a cell line expressing very low levels of retinoic acid receptor-gamma is resistant to the effects of 9-cis-retinoic acid.A retinoic acid receptor-beta/gamma selective antagonist also suppressed the cytotoxic effects of 9-cis-retinoic acid in a dose-dependent manner.Our results encourage further work evaluating the clinical use of receptor subtype selective retinoids in pancreatic carcinoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Gastroenterology, Endocrinology and Metabolism, St George's Hospital Medical School, London SW17 ORE, UK.

ABSTRACT
All-trans-retinoic acid and 9-cis-retinoic acid have been reported to have inhibitory effects on pancreatic adenocarcinoma cells and we have shown that this is partly due to induction of apoptosis. In this study, the mechanisms whereby 9-cis-retinoic acid induces apoptosis in these cells were investigated. An involvement of the Bcl-2 family of proteins was shown, such that 9-cis-retinoic acid causes a decrease in the Bcl-2/Bax ratio. Overexpression of Bcl-2 also resulted in inhibition of apoptosis induced by 9-cis-retinoic acid. Furthermore, two broad-range caspase inhibitors blocked DNA fragmentation induced by 9-cis-retinoic acid, but had no effect on viability defined by mitochondrial activity. Using synthetic retinoids, which bind selectively to specific retinoic acid receptor subtypes, we further established that activation of retinoic acid receptor-gamma is essential for induction of apoptosis. Only pan-retinoic acid receptor and retinoic acid receptor-gamma selective agonists reduced viability and a cell line expressing very low levels of retinoic acid receptor-gamma is resistant to the effects of 9-cis-retinoic acid. A retinoic acid receptor-beta/gamma selective antagonist also suppressed the cytotoxic effects of 9-cis-retinoic acid in a dose-dependent manner. This study provides important insight into the mechanisms involved in suppression of pancreatic tumour cell growth by retinoids. Our results encourage further work evaluating the clinical use of receptor subtype selective retinoids in pancreatic carcinoma.

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Related in: MedlinePlus

The broad-range caspase inhibitors Z-VAD.fmk and Boc-D.fmk specifically inhibited DNA fragmentation induced by 9cRA (A), but had no effect on mitochondrial activity (B). T3M-4 cells were treated with 500 nM 9cRA±50 μM Z-VAD.fmk or 25 μM Boc-D.fmk for 6 days and DNA fragmentation and viability were assessed using the Cell Death Detection ELISA (n=4) and an MTT assay (n=6), respectively. ##Indicates a significant difference compared to 9cRA alone (P<0.01).
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fig4: The broad-range caspase inhibitors Z-VAD.fmk and Boc-D.fmk specifically inhibited DNA fragmentation induced by 9cRA (A), but had no effect on mitochondrial activity (B). T3M-4 cells were treated with 500 nM 9cRA±50 μM Z-VAD.fmk or 25 μM Boc-D.fmk for 6 days and DNA fragmentation and viability were assessed using the Cell Death Detection ELISA (n=4) and an MTT assay (n=6), respectively. ##Indicates a significant difference compared to 9cRA alone (P<0.01).

Mentions: Cells were preincubated with the broad-range caspase inhibitors Z-VAD.fmk or Boc-D.fmk for 3 h before addition of 9cRA. They were subsequently treated for up to 6 days and fresh medium, containing both compounds, was added every 48 h. Addition of either of the inhibitors resulted in a significant decrease in nuclear fragmentation, as determined by Cell Death Detection ELISA on day 6. Interestingly, mitochondrial activity was not affected, and no increase in cell viability was seen at any time point (Figure 4Figure 4


Retinoids cause apoptosis in pancreatic cancer cells via activation of RAR-gamma and altered expression of Bcl-2/Bax.

Pettersson F, Dalgleish AG, Bissonnette RP, Colston KW - Br. J. Cancer (2002)

The broad-range caspase inhibitors Z-VAD.fmk and Boc-D.fmk specifically inhibited DNA fragmentation induced by 9cRA (A), but had no effect on mitochondrial activity (B). T3M-4 cells were treated with 500 nM 9cRA±50 μM Z-VAD.fmk or 25 μM Boc-D.fmk for 6 days and DNA fragmentation and viability were assessed using the Cell Death Detection ELISA (n=4) and an MTT assay (n=6), respectively. ##Indicates a significant difference compared to 9cRA alone (P<0.01).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2376147&req=5

fig4: The broad-range caspase inhibitors Z-VAD.fmk and Boc-D.fmk specifically inhibited DNA fragmentation induced by 9cRA (A), but had no effect on mitochondrial activity (B). T3M-4 cells were treated with 500 nM 9cRA±50 μM Z-VAD.fmk or 25 μM Boc-D.fmk for 6 days and DNA fragmentation and viability were assessed using the Cell Death Detection ELISA (n=4) and an MTT assay (n=6), respectively. ##Indicates a significant difference compared to 9cRA alone (P<0.01).
Mentions: Cells were preincubated with the broad-range caspase inhibitors Z-VAD.fmk or Boc-D.fmk for 3 h before addition of 9cRA. They were subsequently treated for up to 6 days and fresh medium, containing both compounds, was added every 48 h. Addition of either of the inhibitors resulted in a significant decrease in nuclear fragmentation, as determined by Cell Death Detection ELISA on day 6. Interestingly, mitochondrial activity was not affected, and no increase in cell viability was seen at any time point (Figure 4Figure 4

Bottom Line: Only pan-retinoic acid receptor and retinoic acid receptor-gamma selective agonists reduced viability and a cell line expressing very low levels of retinoic acid receptor-gamma is resistant to the effects of 9-cis-retinoic acid.A retinoic acid receptor-beta/gamma selective antagonist also suppressed the cytotoxic effects of 9-cis-retinoic acid in a dose-dependent manner.Our results encourage further work evaluating the clinical use of receptor subtype selective retinoids in pancreatic carcinoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Gastroenterology, Endocrinology and Metabolism, St George's Hospital Medical School, London SW17 ORE, UK.

ABSTRACT
All-trans-retinoic acid and 9-cis-retinoic acid have been reported to have inhibitory effects on pancreatic adenocarcinoma cells and we have shown that this is partly due to induction of apoptosis. In this study, the mechanisms whereby 9-cis-retinoic acid induces apoptosis in these cells were investigated. An involvement of the Bcl-2 family of proteins was shown, such that 9-cis-retinoic acid causes a decrease in the Bcl-2/Bax ratio. Overexpression of Bcl-2 also resulted in inhibition of apoptosis induced by 9-cis-retinoic acid. Furthermore, two broad-range caspase inhibitors blocked DNA fragmentation induced by 9-cis-retinoic acid, but had no effect on viability defined by mitochondrial activity. Using synthetic retinoids, which bind selectively to specific retinoic acid receptor subtypes, we further established that activation of retinoic acid receptor-gamma is essential for induction of apoptosis. Only pan-retinoic acid receptor and retinoic acid receptor-gamma selective agonists reduced viability and a cell line expressing very low levels of retinoic acid receptor-gamma is resistant to the effects of 9-cis-retinoic acid. A retinoic acid receptor-beta/gamma selective antagonist also suppressed the cytotoxic effects of 9-cis-retinoic acid in a dose-dependent manner. This study provides important insight into the mechanisms involved in suppression of pancreatic tumour cell growth by retinoids. Our results encourage further work evaluating the clinical use of receptor subtype selective retinoids in pancreatic carcinoma.

Show MeSH
Related in: MedlinePlus