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Steroidal aromatase inhibitors inhibit growth of hormone-dependent breast cancer cells by inducing cell cycle arrest and apoptosis. Apoptosis 2013; 18:1426-1436. [DOI: 10.1007/s10495-013-0879-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Amaral C, Borges M, Melo S, da Silva ET, Correia-da-Silva G, Teixeira N. Apoptosis and autophagy in breast cancer cells following exemestane treatment. PLoS One 2012; 7:e42398. [PMID: 22912703 PMCID: PMC3418278 DOI: 10.1371/journal.pone.0042398] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 07/05/2012] [Indexed: 01/11/2023] Open
Abstract
Aromatase inhibitors (AIs), which block the conversion of androgens to estrogens, are used for hormone-dependent breast cancer treatment. Exemestane, a steroidal that belongs to the third-generation of AIs, is a mechanism-based inhibitor that binds covalently and irreversibly, inactivating and destabilizing aromatase. Since the biological effects of exemestane in breast cancer cells are not totally understood, its effects on cell viability, cell proliferation and mechanisms of cell death were studied in an ER-positive aromatase-overexpressing breast cancer cell line (MCF-7aro). The effects of 3-methyladenine (3-MA), an inhibitor of autophagy and of ZVAD-FMK, an apoptotic inhibitor, in exemestane treated cells were also investigated. Our results indicate that exemestane induces a strong inhibition in MCF-7aro cell proliferation in a dose- and time-dependent manner, promoting a significant cell cycle arrest in G(0)/G1 or in G(2)/M phases after 3 and 6 days of treatment, respectively. This was accompanied by a decrease in cell viability due to activation of cell death by apoptosis, via mitochondrial pathway and the occurrence of autophagy. Inhibition of autophagy by the autophagic inhibitor, 3-MA, resulted in a reduction of cell viability and activation of caspases. All together the results obtained suggest that exemestane induced mitochondrial-mediated apoptosis and autophagy, which act as a pro-survival process regulating breast cancer cell apoptosis.
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Affiliation(s)
- Cristina Amaral
- Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - Margarida Borges
- Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - Soraia Melo
- Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- Department of Zoology, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | - Elisiário Tavares da Silva
- Center of Pharmaceutical Studies, Pharmaceutical Chemistry Laboratory, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Georgina Correia-da-Silva
- Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - Natércia Teixeira
- Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
- * E-mail:
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Fortunati N, Catalano MG, Boccuzzi G, Frairia R. Sex Hormone-Binding Globulin (SHBG), estradiol and breast cancer. Mol Cell Endocrinol 2010; 316:86-92. [PMID: 19770023 DOI: 10.1016/j.mce.2009.09.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 09/14/2009] [Accepted: 09/14/2009] [Indexed: 01/13/2023]
Abstract
The human serum Sex Hormone-Binding Globulin (SHBG) plays an important role in breast cancer pathophysiology and risk definition, since it regulates the bioavailable fraction of circulating estradiol. We here summarize data reported over the years concerning the involvement of SHBG and SHBG polymorphisms in the definition of breast cancer risk. We also report what is known about the direct action of SHBG in breast cancer cells, illustrating its interaction with these cells and the subsequent initiation of a specific intracellular pathway leading to cross-talk with the estradiol-activated pathway and, finally, to the inhibition of several effects of estradiol in breast cancer cells. In conclusion, as a result of its unique property of regulating the estrogen free fraction and cross-talking with the estradiol pathways, by inhibiting estradiol-induced breast cancer cell growth and proliferation, SHBG is associated with a reduced risk of developing the neoplasm after estrogen exposure.
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Affiliation(s)
- N Fortunati
- Laboratory of Oncological Endocrinology, AUO San Giovanni Battista, Turin, Italy.
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de Medina P, Payré B, Boubekeur N, Bertrand-Michel J, Tercé F, Silvente-Poirot S, Poirot M. Ligands of the antiestrogen-binding site induce active cell death and autophagy in human breast cancer cells through the modulation of cholesterol metabolism. Cell Death Differ 2009; 16:1372-84. [DOI: 10.1038/cdd.2009.62] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Cepa M, Correia-da-Silva G, da Silva EJT, Roleira FMF, Borges M, Teixeira NA. New steroidal aromatase inhibitors: suppression of estrogen-dependent breast cancer cell proliferation and induction of cell death. BMC Cell Biol 2008; 9:41. [PMID: 18652661 PMCID: PMC2515307 DOI: 10.1186/1471-2121-9-41] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Accepted: 07/24/2008] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Aromatase, the cytochrome P-450 enzyme (CYP19) responsible for estrogen biosynthesis, is an important target for the treatment of estrogen-dependent breast cancer. In fact, the use of synthetic aromatase inhibitors (AI), which induce suppression of estrogen synthesis, has shown to be an effective alternative to the classical tamoxifen for the treatment of postmenopausal patients with ER-positive breast cancer. New AIs obtained, in our laboratory, by modification of the A and D-rings of the natural substrate of aromatase, compounds 3a and 4a, showed previously to efficiently suppress aromatase activity in placental microsomes. In the present study we have investigated the effects of these compounds on cell proliferation, cell cycle progression and induction of cell death using the estrogen-dependent human breast cancer cell line stably transfected with the aromatase gene, MCF-7 aro cells. RESULTS The new steroids inhibit hormone-dependent proliferation of MCF-7aro cells in a time and dose-dependent manner, causing cell cycle arrest in G0/G1 phase and inducing cell death with features of apoptosis and autophagic cell death. CONCLUSION Our in vitro studies showed that the two steroidal AIs, 3a and 4a, are potent inhibitors of breast cancer cell proliferation. Moreover, it was also shown that the antiproliferative effects of these two steroids on MCF-7aro cells are mediated by disrupting cell cycle progression, through cell cycle arrest in G0/G1 phase and induction of cell death, being the dominant mechanism autophagic cell death. Our results are important for the elucidation of the cellular effects of steroidal AIs on breast cancer.
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Affiliation(s)
- Margarida Cepa
- Biochemistry Laboratory, Faculty of Pharmacy, University of Oporto, Rua Aníbal Cunha, 164, 4099-030 Oporto, Portugal
- IBMC – Institute for Molecular and Cellular Biology, University of Oporto, 4150-180 Oporto, Portugal
| | - Georgina Correia-da-Silva
- Biochemistry Laboratory, Faculty of Pharmacy, University of Oporto, Rua Aníbal Cunha, 164, 4099-030 Oporto, Portugal
- IBMC – Institute for Molecular and Cellular Biology, University of Oporto, 4150-180 Oporto, Portugal
| | - Elisiário J Tavares da Silva
- Centro de Estudos Farmacêuticos, Pharmaceutical Chemistry Laboratory, Faculty of Pharmacy, University of Coimbra, 3000-295 Coimbra, Portugal
| | - Fernanda MF Roleira
- Centro de Estudos Farmacêuticos, Pharmaceutical Chemistry Laboratory, Faculty of Pharmacy, University of Coimbra, 3000-295 Coimbra, Portugal
| | - Margarida Borges
- Biochemistry Laboratory, Faculty of Pharmacy, University of Oporto, Rua Aníbal Cunha, 164, 4099-030 Oporto, Portugal
- IBMC – Institute for Molecular and Cellular Biology, University of Oporto, 4150-180 Oporto, Portugal
| | - Natércia A Teixeira
- Biochemistry Laboratory, Faculty of Pharmacy, University of Oporto, Rua Aníbal Cunha, 164, 4099-030 Oporto, Portugal
- IBMC – Institute for Molecular and Cellular Biology, University of Oporto, 4150-180 Oporto, Portugal
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Bailly-Maitre B, Bard-Chapeau E, Luciano F, Droin N, Bruey JM, Faustin B, Kress C, Zapata JM, Reed JC. Mice Lackingbi-1Gene Show Accelerated Liver Regeneration. Cancer Res 2007; 67:1442-50. [PMID: 17308082 DOI: 10.1158/0008-5472.can-06-0850] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The liver has enormous regenerative capacity such that, after partial hepatectomy, hepatocytes rapidly replicate to restore liver mass, thus providing a context for studying in vivo mechanisms of cell growth regulation. Bax inhibitor-1 (BI-1) is an evolutionarily conserved endoplasmic reticulum (ER) protein that suppresses cell death. Interestingly, the BI-1 protein has been shown to regulate Ca(2+) handling by the ER similar to antiapoptotic Bcl-2 family proteins. Effects on cell cycle entry by Bcl-2 family proteins have been described, prompting us to explore whether bi-1-deficient mice display alterations in the in vivo regulation of cell cycle entry using a model of liver regeneration. Accordingly, we compared bi-1(+/+) and bi-1(-/-) mice subjected to partial hepatectomy with respect to the kinetics of liver regeneration and molecular events associated with hepatocyte proliferation. We found that bi-1 deficiency accelerates liver regeneration after partial hepatectomy. Regenerating hepatocytes in bi-1(-/-) mice enter cell cycle faster, as documented by more rapid incorporation of deoxynucleotides, associated with earlier increases in cyclin D1, cyclin D3, cyclin-dependent kinase (Cdk) 2, and Cdk4 protein levels, more rapid hyperphosphorylation of retinoblastoma protein, and faster degradation of p27(Kip1). Dephosphorylation and nuclear translocation of nuclear factor of activated T cells 1 (NFAT1), a substrate of the Ca(2+)-sensitive phosphatase calcineurin, were also accelerated following partial hepatectomy in BI-1-deficient hepatocytes. These findings therefore reveal additional similarities between BI-1 and Bcl-2 family proteins, showing a role for BI-1 in regulating cell proliferation in vivo, in addition to its previously described actions as a regulator of cell survival.
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Affiliation(s)
- Béatrice Bailly-Maitre
- Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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Boulay A, Rudloff J, Ye J, Zumstein-Mecker S, O'Reilly T, Evans DB, Chen S, Lane HA. Dual inhibition of mTOR and estrogen receptor signaling in vitro induces cell death in models of breast cancer. Clin Cancer Res 2005; 11:5319-28. [PMID: 16033851 DOI: 10.1158/1078-0432.ccr-04-2402] [Citation(s) in RCA: 270] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE RAD001 (everolimus), a mammalian target of rapamycin (mTOR) pathway inhibitor in phase II clinical trials in oncology, exerts potent antiproliferative/antitumor activities. Many breast cancers are dependent for proliferation on estrogens synthesized from androgens (i.e., androstenedione) by aromatase. Letrozole (Femara) is an aromatase inhibitor used for treatment of postmenopausal women with hormone-dependent breast cancers. The role of the mTOR pathway in estrogen-driven proliferation and effects of combining RAD001 and letrozole were examined in vitro in two breast cancer models. EXPERIMENTAL DESIGN The role of the mTOR pathway in estrogen response was evaluated in aromatase-expressing MCF7/Aro breast cancer cells by immunoblotting. Effects of RAD001 and letrozole (alone and in combination) on the proliferation and survival of MCF7/Aro and T47D/Aro cells were evaluated using proliferation assays, flow cytometry, immunoblotting, and apoptosis analyses. RESULTS Treatment of MCF7/Aro cells with estradiol or androstenedione caused modulation of the mTOR pathway, a phenomenon reversed by letrozole or RAD001. In MCF7/Aro and T47D/Aro cells, both agents inhibited androstenedione-induced proliferation; however, in combination, this was significantly augmented (P < 0.001, two-way ANOVA, synergy by isobologram analysis). Increased activity of the combination correlated with more profound effects on G1 progression and a significant decrease in cell viability (P < 0.01, two-way ANOVA) defined as apoptosis (P < 0.05, Friedman test). Increased cell death was particularly evident with optimal drug concentrations. CONCLUSION mTOR signaling is required for estrogen-induced breast tumor cell proliferation. Moreover, RAD001-letrozole combinations can act in a synergistic manner to inhibit proliferation and trigger apoptotic cell death. This combination holds promise for the treatment of hormone-dependent breast cancers.
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Affiliation(s)
- Anne Boulay
- Novartis Institutes for BioMedical Research Basel, Oncology Research, Novartis Pharma AG, Basel, Switzerland
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Wang LH, Yang XY, Zhang X, Mihalic K, Fan YX, Xiao W, Howard OMZ, Appella E, Maynard AT, Farrar WL. Suppression of breast cancer by chemical modulation of vulnerable zinc fingers in estrogen receptor. Nat Med 2003; 10:40-7. [PMID: 14702633 DOI: 10.1038/nm969] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Accepted: 11/21/2003] [Indexed: 11/09/2022]
Abstract
Current antiestrogen therapy for breast cancer is limited by the mixed estrogenic and antiestrogenic activity of selective estrogen receptor modulators. Here we show that the function of zinc fingers in the estrogen receptor DNA-binding domain (DBD) is susceptible to chemical inhibition by electrophilic disulfide benzamide and benzisothiazolone derivatives, which selectively block binding of the estrogen receptor to its responsive element and subsequent transcription. These compounds also significantly inhibit estrogen-stimulated cell proliferation, markedly reduce tumor mass in nude mice bearing human MCF-7 breast cancer xenografts, and interfere with cell-cycle and apoptosis regulatory gene expression. Functional assays and computational analysis support a molecular mechanism whereby electrophilic agents preferentially disrupt the vulnerable C-terminal zinc finger, thus suppressing estrogen receptor-mediated breast carcinoma progression. Our results provide the proof of principle for a new strategy to inhibit breast cancer at the level of DNA binding, rather than the classical antagonism of estrogen binding.
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Affiliation(s)
- Li Hua Wang
- Basic Research Program, SAIC-Frederick, National Cancer Institute-Frederick, National Institutes of Health, PO Box B, Frederick, Maryland 21702, USA.
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Negulescu O, Bognar I, Lei J, Devarajan P, Silbiger S, Neugarten J. Estradiol reverses TGF-beta1-induced mesangial cell apoptosis by a casein kinase 2-dependent mechanism. Kidney Int 2002; 62:1989-98. [PMID: 12427123 DOI: 10.1046/j.1523-1755.2002.00679.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The slower rate of progression of chronic renal disease in women than in men is explained in part by the ability of estradiol to reverse the stimulatory effect of transforming growth factor-beta1 (TGF-beta1) on collagen IV synthesis at the level of casein kinase 2 activation. Casein kinase 2 also phosphorylates and activates the pro-apoptotic protein, p53. We hypothesized that estradiol would reverse TGF-beta1-induced mesangial cell apoptosis by antagonizing the stimulatory effects of TGF-beta1 on casein kinase 2 activity, thereby preventing p53 activation. METHODS The effects of TGF-beta1 on mesangial cell apoptosis, p53 phosphorylation, Bax and Bcl-2 levels, caspase 9 activity, and cleavage of PARP were examined. The abilities of estradiol and a specific inhibitor of CK2 (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole) (DRB) to modulate the effects of TGF-beta1 on these processes were also examined. RESULTS TGF-beta1 (2 ng/mL), which up-regulates CK2 activity, induces apoptosis in murine mesangial cells together with p53 serine389 phosphorylation, up-regulation of Bax, suppression of Bcl-2, destabilization of mitochondrial permeability transition pores, stimulation of caspase 9 activity and activation of PARP. TGF-beta1-induced p53 activation and all the intermediary steps leading to mesangial cell apoptosis were reversed by estradiol (10-9 mol/L) and by DRB, potent inhibitors of CK2 activity, but not by inhibitors of the p38 MAPK, ERK or JNK signaling cascades. In contrast, TGF-beta1 failed to induce apoptosis in p53 knockout mesangial cells. CONCLUSIONS Our data suggest that CK2 mediates the stimulatory effects of TGF-beta1 on mesangial cell apoptosis via a p53-dependent mechanism. The ability of estradiol to reverse TGF-beta1-induced apoptosis may contribute to the protective effects of female gender on the course of chronic renal disease.
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Affiliation(s)
- Olivia Negulescu
- Division of Nephrology, Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York 10467, USA
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Carré M, André N, Carles G, Borghi H, Brichese L, Briand C, Braguer D. Tubulin is an inherent component of mitochondrial membranes that interacts with the voltage-dependent anion channel. J Biol Chem 2002; 277:33664-9. [PMID: 12087096 DOI: 10.1074/jbc.m203834200] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously reported that anti-tubulin agents induce the release of cytochrome c from isolated mitochondria. In this study, we show that tubulin is present in mitochondria isolated from different human cancerous and non-cancerous cell lines. The absence of polymerized microtubules and cytosolic proteins was checked to ensure that this tubulin is an inherent component of the mitochondria. In addition, a salt wash did not release the tubulin from the mitochondria. By using electron microscopy, we then showed that tubulin is localized in the mitochondrial membranes. As compared with cellular tubulin, mitochondrial tubulin is enriched in acetylated and tyrosinated alpha-tubulin and is also enriched in the class III beta-tubulin isotype but contains very little of the class IV beta-tubulin isotype. The mitochondrial tubulin is likely to be organized in alpha/beta dimers and represents 2.2 +/- 0.5% of total cellular tubulin. Lastly, we showed by immunoprecipitation experiments that the mitochondrial tubulin is specifically associated with the voltage-dependent anion channel, the main component of the permeability transition pore. Thus, tubulin is an inherent component of mitochondrial membranes, and it could play a role in apoptosis via interaction with the permeability transition pore.
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Affiliation(s)
- Manon Carré
- UMR CNRS 6032, UFR Pharmacy, University of La Méditerranée, 27 Boulevard Jean Moulin, 13005 Marseille, France
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Brichese L, Barboule N, Heliez C, Valette A. Bcl-2 phosphorylation and proteasome-dependent degradation induced by paclitaxel treatment: consequences on sensitivity of isolated mitochondria to Bid. Exp Cell Res 2002; 278:101-11. [PMID: 12126962 DOI: 10.1006/excr.2002.5563] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several studies have suggested that Bcl-2 phosphorylation, which occurs during mitotic arrest induced by paclitaxel, inhibits its antiapoptotic function. In the present study, we demonstrated that the level of phosphorylated Bcl-2 was threefold higher in mitochondria than in the nuclear membrane or endoplasmic reticulum. Our results show, in isolated mitochondria, that phosphorylation of Bcl-2 in mitosis does not modify either its integration into the mitochondrial membrane or the ability to release cytochrome c in response to Bid, a cytochrome c releasing agent. In HeLa cells, in which paclitaxel induces apoptosis, the nonphosphorylated form of Bcl-2 is degraded by a proteasome-dependent degradation pathway, whereas the phosphorylated forms of mitochondrial Bcl-2 appear to be resistant to proteasome-induced degradation. We found that low concentrations of recombinant Bid triggered a greater release of cytochrome c from mitochondria isolated from paclitaxel-treated HeLa cells than from mitochondria isolated from control HeLa cells. Taken together, these results show that Bcl-2 phosphorylation does not inhibit its function. On the contrary, Bcl-2 phosphorylation indirectly regulated its antiapoptotic action via protection against degradation. Indeed, in response to paclitaxel treatment, the level of Bcl-2 expression in mitochondria rather than its phosphorylation state could regulate the sensitivity of mitochondria to cytochrome c releasing agents in vitro.
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Affiliation(s)
- L Brichese
- LBCMCP, UMR CNRS 5088, Université Paul Sabatier, 31, Toulouse, France
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Vail ME, Chaisson ML, Thompson J, Fausto N. Bcl-2 expression delays hepatocyte cell cycle progression during liver regeneration. Oncogene 2002; 21:1548-55. [PMID: 11896583 DOI: 10.1038/sj.onc.1205212] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2001] [Revised: 11/28/2001] [Accepted: 11/28/2001] [Indexed: 11/09/2022]
Abstract
Bcl-2 is the prototype of a family of genes that prevent apoptosis. However, several reports indicate that Bcl-2 may also act as a cell cycle modulator. In several human tumors, Bcl-2 expression correlates with a more favorable prognosis and lower tumor proliferative activity. We have shown that Bcl-2 expression delays liver tumor development in transgenic mice even when the gene is turned on shortly before the time of tumor development. We hypothesized that Bcl-2 may delay liver tumorigenesis by interfering with hepatocyte proliferation. To test whether Bcl-2 expression may act on hepatocyte replication we studied liver regeneration in Bcl-2 transgenic mice and wild-type littermates. DNA replication was delayed by approximately 8 h in Bcl-2 transgenic mice compared to the timing of the response in wild-type littermates. Cyclin D expression showed no alterations in the regenerating liver of Bcl-2 transgenic mice. In contrast, there was a delay in the expression of p107, cyclin E and in the activity of cyclin E/cdk 2 activity. These results show that Bcl-2 expression delays cell cycle progression in hepatocytes and suggests that it acts at a step involving cyclin E and p107.
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Affiliation(s)
- Mary E Vail
- Department of Pathology, University of Washington, Seattle, Washington, WA 98195-7705, USA
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Santen RJ, Song RX, McPherson R, Kumar R, Adam L, Jeng MH, Yue W. The role of mitogen-activated protein (MAP) kinase in breast cancer. J Steroid Biochem Mol Biol 2002; 80:239-56. [PMID: 11897507 DOI: 10.1016/s0960-0760(01)00189-3] [Citation(s) in RCA: 292] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mitogen-activated protein kinase (MAP kinase) cascades transmit and amplify signals involved in cell proliferation as well as cell death. These signal transduction pathways serve as an indicators of the intensity of trafficking induced by various growth factor, steroid hormone, and G protein receptor mediated ligands. Three major MAP kinase pathways exist in human tissues, but the one involving ERK-1 and -2 is most relevant to breast cancer. Peptide growth factors acting through tyrosine kinase containing receptors are the major regulators of ERK-1 and -2. Estradiol, progesterone, and testosterone can act non-genomically via membrane associated receptors to activate MAP kinase as can various other ligands acting through heterotrimeric G protein receptors. Recent studies demonstrate that breast cancers frequently contain an increased proportion of cells with the activated form of MAP kinase. In estrogen receptor positive breast tumors, MAP kinase pathways can exert "cross talk" effects at the level of ER induced transcription as well as at the level of the cell cycle. Estradiol stimulates cell proliferation by mechanisms which involve activation of MAP kinase, either through rapid, non-transcription effects or by increasing growth factor production and consequently MAP kinase. Progesterone and androgens also stimulate MAP kinase through both of these two mechanisms. Strategies used to treat hormone dependent breast cancer appear to result in upregulation of MAP kinase activation. Direct experimental data demonstrate that the pressure of estradiol deprivation results in the upregulation of MAP kinase in breast cancer cells growing in tissue culture and as xenografts. A number of investigators have now studied the expression of activated MAP kinase in human breast cancer tissues by enzymatic assay and by immunohistochemical techniques. Approximately half of breast tumors express more activated MAP kinase than does the surrounding benign tissue. Studies show a trend toward higher MAP kinase activity in primary tumors of node positive than in node negative patients. However, larger numbers of patients must be studied for these results to achieve statistical significance. The up-regulation of MAP kinase activity does not represent mutations of Ras, but appears to result from enhancement of growth factor pathway activation. No data are yet available on the relationship between MAP kinase activation and apoptosis. Additional studies are now needed to determine the precise relationship between MAP kinase activation and tumor proliferation, apoptosis, and degree of invasiveness as well as on disease free and overall survival.
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Affiliation(s)
- Richard J Santen
- Department of Medicine, Division of Endocrinology, University of Virginia Health System, P.O. Box 800379, Charlottesville, VA 22908, USA.
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