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Gene expression profiling reveals effects of Cimicifuga racemosa (L.) NUTT. (black cohosh) on the estrogen receptor positive human breast cancer cell line MCF-7.

Gaube F, Wolfl S, Pusch L, Kroll TC, Hamburger M - BMC Pharmacol. (2007)

Bottom Line: Also several transcripts coding for oxidoreductases were induced, as for example the cytochrome P450 family members 1A1 and 1B1.In addition, some transcripts associated with antitumor but also tumor-promoting activity were regulated.The effects may be results of the activation of different pathways.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Pharmacy, Department of Pharmaceutical Biology, University of Jena, Semmelweisstr, 10, 07743 Jena, Germany. Friedemann.Gaube@uni-jena.de

ABSTRACT

Background: Extracts from the rhizome of Cimicifuga racemosa (black cohosh) are increasingly popular as herbal alternative to hormone replacement therapy (HRT) for the alleviation of postmenopausal disorders. However, the molecular mode of action and the active principles are presently not clear. Previously published data have been largely contradictory. We, therefore, investigated the effects of a lipophilic black cohosh rhizome extract and cycloartane-type triterpenoids on the estrogen receptor positive human breast cancer cell line MCF-7.

Results: Both extract and purified compounds clearly inhibited cellular proliferation. Gene expression profiling with the extract allowed us to identify 431 regulated genes with high significance. The extract induced expression pattern differed from those of 17beta-estradiol or the estrogen receptor antagonist tamoxifen. We observed a significant enrichment of genes in an anti-proliferative and apoptosis-sensitizing manner, as well as an increase of mRNAs coding for gene products involved in several stress response pathways. These functional groups were highly overrepresented among all regulated genes. Also several transcripts coding for oxidoreductases were induced, as for example the cytochrome P450 family members 1A1 and 1B1. In addition, some transcripts associated with antitumor but also tumor-promoting activity were regulated. Real-Time RT-PCR analysis of 13 selected genes was conducted after treatment with purified compounds - the cycloartane-type triterpene glycoside actein and triterpene aglycons - showing similar expression levels compared to the extract.

Conclusion: No estrogenic but antiproliferative and proapoptotic gene expression was shown for black cohosh in MCF-7 cells at the transcriptional level. The effects may be results of the activation of different pathways. The cycloartane glycosides and - for the first time - their aglycons could be identified as an active principle in black cohosh.

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Stress response pathways affected by black cohosh at the transcriptional level. Genes marked by boxes were regulated in MCF-7 cells after treatment with black cohosh extract. ↑ represents up-regulation, ↓ represents down-regulation. (Abbreviations: ATF6, activating transcription factor 6; XBP1, x box binding protein 1; IRE1α, Serine/threonine-protein kinase/endoribonuclease, Inositol-requiring 1).
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Figure 6: Stress response pathways affected by black cohosh at the transcriptional level. Genes marked by boxes were regulated in MCF-7 cells after treatment with black cohosh extract. ↑ represents up-regulation, ↓ represents down-regulation. (Abbreviations: ATF6, activating transcription factor 6; XBP1, x box binding protein 1; IRE1α, Serine/threonine-protein kinase/endoribonuclease, Inositol-requiring 1).

Mentions: In relation to the results above, overexpression of transcripts involved with response to cellular stress was highly statistically significant after treatment with black cohosh extract. Among different functional categories we identified some 40 transcripts associated with metabolic stress response such as hypoxia [47], mal- or unfolded protein response in the endoplasmic reticulum [48,49] or starvation for amino acids or glucose [50,51] (Figure 6). Transcript of hypoxia inducible factor 1α (HIF1α; HIF1A), a key regulator in hypoxia, was upregulated. A heterodimer of HIF1α/ARNT (HIF1) binds to hypoxia-responsive elements (HREs), thereby regulating the expression of hypoxia-response genes. Vascular endothelial growth factor (VEGF), heme oxygenase 1 (HMOX1), basic helix-loop-helix domain containing, class B, 2 (BHLHB2), p21cip1 and DDIT4 – these transcripts were also upregulated – are known to be direct target genes [47,52,53]. A hypoxia response pathway via mTOR (mammalian target of rapamycin) including inactivation of EIF4EBP1 (Eukaryotic translation initiation factor 4E binding protein 1) and finally resulting in increased mRNA translation is known to be inhibited by DDIT4 [52]. This could explain the increase of EIF4EBP1 mRNA we observed in our experiment. The increases of CCAAT/enhancer binding protein, beta (CEBPB), endothelial PAS domain protein 1 (EPAS1=HIF2α), early growth response 1 (EGR1) and sestrin 2 (SESN2) mRNA are also related to hypoxia [53,54].


Gene expression profiling reveals effects of Cimicifuga racemosa (L.) NUTT. (black cohosh) on the estrogen receptor positive human breast cancer cell line MCF-7.

Gaube F, Wolfl S, Pusch L, Kroll TC, Hamburger M - BMC Pharmacol. (2007)

Stress response pathways affected by black cohosh at the transcriptional level. Genes marked by boxes were regulated in MCF-7 cells after treatment with black cohosh extract. ↑ represents up-regulation, ↓ represents down-regulation. (Abbreviations: ATF6, activating transcription factor 6; XBP1, x box binding protein 1; IRE1α, Serine/threonine-protein kinase/endoribonuclease, Inositol-requiring 1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2194763&req=5

Figure 6: Stress response pathways affected by black cohosh at the transcriptional level. Genes marked by boxes were regulated in MCF-7 cells after treatment with black cohosh extract. ↑ represents up-regulation, ↓ represents down-regulation. (Abbreviations: ATF6, activating transcription factor 6; XBP1, x box binding protein 1; IRE1α, Serine/threonine-protein kinase/endoribonuclease, Inositol-requiring 1).
Mentions: In relation to the results above, overexpression of transcripts involved with response to cellular stress was highly statistically significant after treatment with black cohosh extract. Among different functional categories we identified some 40 transcripts associated with metabolic stress response such as hypoxia [47], mal- or unfolded protein response in the endoplasmic reticulum [48,49] or starvation for amino acids or glucose [50,51] (Figure 6). Transcript of hypoxia inducible factor 1α (HIF1α; HIF1A), a key regulator in hypoxia, was upregulated. A heterodimer of HIF1α/ARNT (HIF1) binds to hypoxia-responsive elements (HREs), thereby regulating the expression of hypoxia-response genes. Vascular endothelial growth factor (VEGF), heme oxygenase 1 (HMOX1), basic helix-loop-helix domain containing, class B, 2 (BHLHB2), p21cip1 and DDIT4 – these transcripts were also upregulated – are known to be direct target genes [47,52,53]. A hypoxia response pathway via mTOR (mammalian target of rapamycin) including inactivation of EIF4EBP1 (Eukaryotic translation initiation factor 4E binding protein 1) and finally resulting in increased mRNA translation is known to be inhibited by DDIT4 [52]. This could explain the increase of EIF4EBP1 mRNA we observed in our experiment. The increases of CCAAT/enhancer binding protein, beta (CEBPB), endothelial PAS domain protein 1 (EPAS1=HIF2α), early growth response 1 (EGR1) and sestrin 2 (SESN2) mRNA are also related to hypoxia [53,54].

Bottom Line: Also several transcripts coding for oxidoreductases were induced, as for example the cytochrome P450 family members 1A1 and 1B1.In addition, some transcripts associated with antitumor but also tumor-promoting activity were regulated.The effects may be results of the activation of different pathways.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Pharmacy, Department of Pharmaceutical Biology, University of Jena, Semmelweisstr, 10, 07743 Jena, Germany. Friedemann.Gaube@uni-jena.de

ABSTRACT

Background: Extracts from the rhizome of Cimicifuga racemosa (black cohosh) are increasingly popular as herbal alternative to hormone replacement therapy (HRT) for the alleviation of postmenopausal disorders. However, the molecular mode of action and the active principles are presently not clear. Previously published data have been largely contradictory. We, therefore, investigated the effects of a lipophilic black cohosh rhizome extract and cycloartane-type triterpenoids on the estrogen receptor positive human breast cancer cell line MCF-7.

Results: Both extract and purified compounds clearly inhibited cellular proliferation. Gene expression profiling with the extract allowed us to identify 431 regulated genes with high significance. The extract induced expression pattern differed from those of 17beta-estradiol or the estrogen receptor antagonist tamoxifen. We observed a significant enrichment of genes in an anti-proliferative and apoptosis-sensitizing manner, as well as an increase of mRNAs coding for gene products involved in several stress response pathways. These functional groups were highly overrepresented among all regulated genes. Also several transcripts coding for oxidoreductases were induced, as for example the cytochrome P450 family members 1A1 and 1B1. In addition, some transcripts associated with antitumor but also tumor-promoting activity were regulated. Real-Time RT-PCR analysis of 13 selected genes was conducted after treatment with purified compounds - the cycloartane-type triterpene glycoside actein and triterpene aglycons - showing similar expression levels compared to the extract.

Conclusion: No estrogenic but antiproliferative and proapoptotic gene expression was shown for black cohosh in MCF-7 cells at the transcriptional level. The effects may be results of the activation of different pathways. The cycloartane glycosides and - for the first time - their aglycons could be identified as an active principle in black cohosh.

Show MeSH
Related in: MedlinePlus