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The aldehyde dehydrogenase enzyme 7A1 is functionally involved in prostate cancer bone metastasis.

van den Hoogen C, van der Horst G, Cheung H, Buijs JT, Pelger RC, van der Pluijm G - Clin. Exp. Metastasis (2011)

Bottom Line: Knockdown of ALDH7A1 resulted in decreased intra-bone growth and inhibited experimentally induced (bone) metastasis, while intra-prostatic growth was not affected.In line with these observations, evidence is presented that TGF-β, a key player in cancer invasiveness and bone metastasis, strongly induced ALDH activity while BMP7 (an antagonist of TGF-β signaling) down-regulated ALDH activity.Our findings show, for the first time, that the ALDH7A1 enzyme is functionally involved in the formation of bone metastases and that the effect appeared dependent on the microenvironment, i.e., bone versus prostate.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Leiden University Medical Centre, The Netherlands.

ABSTRACT
High aldehyde dehydrogenase (ALDH) activity can be used to identify tumor-initiating and metastasis-initiating cells in various human carcinomas, including prostate cancer. To date, the functional importance of ALDH enzymes in prostate carcinogenesis, progression and metastasis has remained elusive. Previously we identified strong expression of ALDH7A1 in human prostate cancer cell lines, primary tumors and matched bone metastases. In this study, we evaluated whether ALDH7A1 is required for the acquisition of a metastatic stem/progenitor cell phenotype in human prostate cancer. Knockdown of ALDH7A1 expression resulted in a decrease of the α2(hi)/αv(hi)/CD44(+) stem/progenitor cell subpopulation in the human prostate cancer cell line PC-3M-Pro4. In addition, ALDH7A1 knockdown significantly inhibited the clonogenic and migratory ability of human prostate cancer cells in vitro. Furthermore, a number of genes/factors involved in migration, invasion and metastasis were affected including transcription factors (snail, snail2, and twist) and osteopontin, an ECM molecule involved in metastasis. Knockdown of ALDH7A1 resulted in decreased intra-bone growth and inhibited experimentally induced (bone) metastasis, while intra-prostatic growth was not affected. In line with these observations, evidence is presented that TGF-β, a key player in cancer invasiveness and bone metastasis, strongly induced ALDH activity while BMP7 (an antagonist of TGF-β signaling) down-regulated ALDH activity. Our findings show, for the first time, that the ALDH7A1 enzyme is functionally involved in the formation of bone metastases and that the effect appeared dependent on the microenvironment, i.e., bone versus prostate.

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Regulation of the PC-3M-Pro4luc subpopulation with high ALDH activity. a Human prostate cancer cells (PC-3M-Pro4luc) were assayed with the ALDEFLUOR® kit after stimulation for 3 days with different concentrations of either BMP7 (50, 100, and 500 ng/ml) or TGF-β (1, 5, and 10 ng/ml). b PC-3M-Pro4luc were assayed with the ALDEFLUOR® kit after stimulation for 3 days with either BMPs (100 ng/ml BMP2, 4, 6, and 500 ng/ml BMP7) or 10 ng/ml TGF-β. c mRNA expression levels of ALDH7A1 in PC-3M-Pro4luc cells after stimulation for 3 days with either BMPs (BMP2, 4, 6, and 7) or TGF-β as detected by qPCR. Data are representative for two independent experiments. d Western blot analysis of ALDH7A1 protein expression after stimulation of PC-3M-Pro4luc cells with TGF-β for 72 h. Intensities were normalized for β-actin
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Fig5: Regulation of the PC-3M-Pro4luc subpopulation with high ALDH activity. a Human prostate cancer cells (PC-3M-Pro4luc) were assayed with the ALDEFLUOR® kit after stimulation for 3 days with different concentrations of either BMP7 (50, 100, and 500 ng/ml) or TGF-β (1, 5, and 10 ng/ml). b PC-3M-Pro4luc were assayed with the ALDEFLUOR® kit after stimulation for 3 days with either BMPs (100 ng/ml BMP2, 4, 6, and 500 ng/ml BMP7) or 10 ng/ml TGF-β. c mRNA expression levels of ALDH7A1 in PC-3M-Pro4luc cells after stimulation for 3 days with either BMPs (BMP2, 4, 6, and 7) or TGF-β as detected by qPCR. Data are representative for two independent experiments. d Western blot analysis of ALDH7A1 protein expression after stimulation of PC-3M-Pro4luc cells with TGF-β for 72 h. Intensities were normalized for β-actin

Mentions: Incubation with different concentrations of TGF-β for 72 h significantly and dose-dependently increased the size of the ALDHhi subpopulation of prostate cancer stem/progenitor cells, whereas incubation with different concentrations of BMP7 significantly and dose-dependently decreased the size of this subpopulation (Fig. 5a). Incubation with BMP2, BMP4, and BMP7 decreased the size of the ALDHhi subpopulation significantly (−56, −62, and −67%, respectively), while the close homolog of BMP7, BMP6, only marginally affected this subpopulation with −25% (Fig. 5b).Fig. 5


The aldehyde dehydrogenase enzyme 7A1 is functionally involved in prostate cancer bone metastasis.

van den Hoogen C, van der Horst G, Cheung H, Buijs JT, Pelger RC, van der Pluijm G - Clin. Exp. Metastasis (2011)

Regulation of the PC-3M-Pro4luc subpopulation with high ALDH activity. a Human prostate cancer cells (PC-3M-Pro4luc) were assayed with the ALDEFLUOR® kit after stimulation for 3 days with different concentrations of either BMP7 (50, 100, and 500 ng/ml) or TGF-β (1, 5, and 10 ng/ml). b PC-3M-Pro4luc were assayed with the ALDEFLUOR® kit after stimulation for 3 days with either BMPs (100 ng/ml BMP2, 4, 6, and 500 ng/ml BMP7) or 10 ng/ml TGF-β. c mRNA expression levels of ALDH7A1 in PC-3M-Pro4luc cells after stimulation for 3 days with either BMPs (BMP2, 4, 6, and 7) or TGF-β as detected by qPCR. Data are representative for two independent experiments. d Western blot analysis of ALDH7A1 protein expression after stimulation of PC-3M-Pro4luc cells with TGF-β for 72 h. Intensities were normalized for β-actin
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Fig5: Regulation of the PC-3M-Pro4luc subpopulation with high ALDH activity. a Human prostate cancer cells (PC-3M-Pro4luc) were assayed with the ALDEFLUOR® kit after stimulation for 3 days with different concentrations of either BMP7 (50, 100, and 500 ng/ml) or TGF-β (1, 5, and 10 ng/ml). b PC-3M-Pro4luc were assayed with the ALDEFLUOR® kit after stimulation for 3 days with either BMPs (100 ng/ml BMP2, 4, 6, and 500 ng/ml BMP7) or 10 ng/ml TGF-β. c mRNA expression levels of ALDH7A1 in PC-3M-Pro4luc cells after stimulation for 3 days with either BMPs (BMP2, 4, 6, and 7) or TGF-β as detected by qPCR. Data are representative for two independent experiments. d Western blot analysis of ALDH7A1 protein expression after stimulation of PC-3M-Pro4luc cells with TGF-β for 72 h. Intensities were normalized for β-actin
Mentions: Incubation with different concentrations of TGF-β for 72 h significantly and dose-dependently increased the size of the ALDHhi subpopulation of prostate cancer stem/progenitor cells, whereas incubation with different concentrations of BMP7 significantly and dose-dependently decreased the size of this subpopulation (Fig. 5a). Incubation with BMP2, BMP4, and BMP7 decreased the size of the ALDHhi subpopulation significantly (−56, −62, and −67%, respectively), while the close homolog of BMP7, BMP6, only marginally affected this subpopulation with −25% (Fig. 5b).Fig. 5

Bottom Line: Knockdown of ALDH7A1 resulted in decreased intra-bone growth and inhibited experimentally induced (bone) metastasis, while intra-prostatic growth was not affected.In line with these observations, evidence is presented that TGF-β, a key player in cancer invasiveness and bone metastasis, strongly induced ALDH activity while BMP7 (an antagonist of TGF-β signaling) down-regulated ALDH activity.Our findings show, for the first time, that the ALDH7A1 enzyme is functionally involved in the formation of bone metastases and that the effect appeared dependent on the microenvironment, i.e., bone versus prostate.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Leiden University Medical Centre, The Netherlands.

ABSTRACT
High aldehyde dehydrogenase (ALDH) activity can be used to identify tumor-initiating and metastasis-initiating cells in various human carcinomas, including prostate cancer. To date, the functional importance of ALDH enzymes in prostate carcinogenesis, progression and metastasis has remained elusive. Previously we identified strong expression of ALDH7A1 in human prostate cancer cell lines, primary tumors and matched bone metastases. In this study, we evaluated whether ALDH7A1 is required for the acquisition of a metastatic stem/progenitor cell phenotype in human prostate cancer. Knockdown of ALDH7A1 expression resulted in a decrease of the α2(hi)/αv(hi)/CD44(+) stem/progenitor cell subpopulation in the human prostate cancer cell line PC-3M-Pro4. In addition, ALDH7A1 knockdown significantly inhibited the clonogenic and migratory ability of human prostate cancer cells in vitro. Furthermore, a number of genes/factors involved in migration, invasion and metastasis were affected including transcription factors (snail, snail2, and twist) and osteopontin, an ECM molecule involved in metastasis. Knockdown of ALDH7A1 resulted in decreased intra-bone growth and inhibited experimentally induced (bone) metastasis, while intra-prostatic growth was not affected. In line with these observations, evidence is presented that TGF-β, a key player in cancer invasiveness and bone metastasis, strongly induced ALDH activity while BMP7 (an antagonist of TGF-β signaling) down-regulated ALDH activity. Our findings show, for the first time, that the ALDH7A1 enzyme is functionally involved in the formation of bone metastases and that the effect appeared dependent on the microenvironment, i.e., bone versus prostate.

Show MeSH
Related in: MedlinePlus