Calycosin suppresses breast cancer cell growth via ERβ-dependent regulation of IGF-1R, p38 MAPK and PI3K/Akt pathways.
PLoS One 2014;
9:e91245. [PMID:
24618835 PMCID:
PMC3949755 DOI:
10.1371/journal.pone.0091245]
[Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 02/11/2014] [Indexed: 12/27/2022] Open
Abstract
We previously reported that calycosin, a natural phytoestrogen structurally similar to estrogen, successfully triggered apoptosis of estrogen receptor (ER)-positive breast cancer cell line, MCF-7. To better understand the antitumor activities of calycosin against breast cancer, besides MCF-7 cells, another ER-positive cell line T-47D was analyzed here, with ER-negative cell lines (MDA-231, MDA-435) as control. Notably, calycosin led to inhibited cell proliferation and apoptosis only in ER-positive cells, particularly in MCF-7 cells, whereas no such effect was observed in ER-negative cells. Then we investigated whether regulation of ERβ, a subtype of ER, contributed to calycosin-induced apoptosis in breast cancer cells. The results showed that incubation of calycosin resulted in enhanced expression ERβ in MCF-7 and T-47D cells, rather than MDA-231 and MDA-435 cells. Moreover, with the upregulation of ERβ, successive changes in downstream signaling pathways were found, including inactivation of insulin-like growth factor 1 receptor (IGF-1R), then stimulation of p38 MAPK and suppression of the serine/threonine kinase (Akt), and finally poly(ADP-ribose) polymerase 1 (PARP-1) cleavage. However, the other two members of the mitogen-activated protein kinase (MAPK) family, extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK), were not consequently regulated by downregulated IGF-1R, indicating ERK 1/2 and JNK pathways were not necessary to allow proliferation inhibition by calycosin. Taken together, our results indicate that calycosin tends to inhibit growth and induce apoptosis in ER-positive breast cancer cells, which is mediated by ERβ-induced inhibition of IGF-1R, along with the selective regulation of MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt pathways.
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