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1.
Int J Mol Sci ; 16(4): 7655-71, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25853264

RESUMO

There is increasing evidence that prenatal exposure to environmental factors may modify breast cancer risk later in life. This study aimed to investigate the effects of in utero exposure to low-dose alcohol on mammary development and tumor risk. Pregnant MMTV-erbB-2 mice were exposed to alcohol (6 g/kg/day) between day 13 and day 19 of gestation, and the female offspring were examined for tumor risk. Whole mount analysis indicated that in utero exposure to low-dose alcohol induced significant increases in ductal extension at 10 weeks of age. Molecular analysis showed that in utero alcohol exposure induced upregulation of ERα signaling and activation of Akt and Erk1/2 in pubertal mammary glands. However, enhanced signaling in the EGFR/erbB-2 pathway appeared to be more prominent in 10-week-old glands than did signaling in the other pathways. Interestingly, tumor development in mice with in utero exposure to low-dose alcohol was slightly delayed compared to control mice, but tumor multiplicity was increased. The results indicate that in utero exposure to low-dose alcohol induces the reprogramming of mammary development by mechanisms that include altered signaling in the estrogen receptor (ER) and erbB-2 pathways. The intriguing tumor development pattern might be related to alcohol dose and exposure conditions, and warrants further investigation.


Assuntos
Etanol/toxicidade , Glândulas Mamárias Animais/efeitos dos fármacos , Neoplasias Mamárias Experimentais/patologia , Efeitos Tardios da Exposição Pré-Natal/patologia , Receptor ErbB-2/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Transformação Celular Viral/genética , Receptor alfa de Estrogênio/metabolismo , Etanol/farmacologia , Feminino , Feto/efeitos dos fármacos , Glândulas Mamárias Animais/crescimento & desenvolvimento , Glândulas Mamárias Animais/patologia , Neoplasias Mamárias Experimentais/induzido quimicamente , Neoplasias Mamárias Experimentais/virologia , Vírus do Tumor Mamário do Camundongo/patogenicidade , Camundongos , Camundongos Transgênicos , Gravidez , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Receptor ErbB-2/genética , Regulação para Cima
2.
J Biol Chem ; 288(34): 24809-24, 2013 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-23853093

RESUMO

Melanoma antigen-A11 (MAGE-A11) is a low-abundance, primate-specific steroid receptor coregulator in normal tissues of the human reproductive tract that is expressed at higher levels in prostate cancer. Increased expression of MAGE-A11 enhances androgen receptor transcriptional activity and promotes prostate cancer cell growth. Further investigation into the mechanisms of MAGE-A11 function in prostate cancer demonstrated interactions with the retinoblastoma-related protein p107 and Rb tumor suppressor but no interaction with p130 of the Rb family. MAGE-A11 interaction with p107 was associated with transcriptional repression in cells with low MAGE-A11 and transcriptional activation in cells with higher MAGE-A11. Selective interaction of MAGE-A11 with retinoblastoma family members suggested the regulation of E2F transcription factors. MAGE-A11 stabilized p107 by inhibition of ubiquitination and linked p107 to hypophosphorylated E2F1 in association with the stabilization and activation of E2F1. The androgen receptor and MAGE-A11 modulated endogenous expression of the E2F1-regulated cyclin-dependent kinase inhibitor p27(Kip1). The ability of MAGE-A11 to increase E2F1 transcriptional activity was similar to the activity of adenovirus early oncoprotein E1A and depended on MAGE-A11 interactions with p107 and p300. The immunoreactivity of p107 and MAGE-A11 was greater in advanced prostate cancer than in benign prostate, and knockdown with small inhibitory RNA showed that p107 is a transcriptional activator in prostate cancer cells. These results suggest that MAGE-A11 is a proto-oncogene whose increased expression in prostate cancer reverses retinoblastoma-related protein p107 from a transcriptional repressor to a transcriptional activator of the androgen receptor and E2F1.


Assuntos
Antígenos de Neoplasias/metabolismo , Fator de Transcrição E2F1/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias da Próstata/metabolismo , Proteína p107 Retinoblastoma-Like/metabolismo , Transcrição Gênica , Proteínas E1A de Adenovirus/genética , Proteínas E1A de Adenovirus/metabolismo , Animais , Antígenos de Neoplasias/genética , Células COS , Chlorocebus aethiops , Inibidor de Quinase Dependente de Ciclina p27/genética , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Proteína p300 Associada a E1A/genética , Proteína p300 Associada a E1A/metabolismo , Fator de Transcrição E2F1/genética , Células HeLa , Humanos , Masculino , Proteínas de Neoplasias/genética , Fosforilação/genética , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Estabilidade Proteica , Proto-Oncogene Mas , Receptores Androgênicos/biossíntese , Receptores Androgênicos/genética , Proteína p107 Retinoblastoma-Like/genética
3.
J Biol Chem ; 288(3): 1939-52, 2013 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-23172223

RESUMO

Prostate cancer growth and progression depend on androgen receptor (AR) signaling through transcriptional mechanisms that require interactions with coregulatory proteins, one of which is the primate-specific steroid receptor coregulator melanoma antigen-A11 (MAGE-A11). In this report, we provide evidence how increased expression of MAGE-A11 during prostate cancer progression enhances AR signaling and prostate cancer growth. MAGE-A11 protein levels were highest in castration-recurrent prostate cancer. The cyclic AMP-induced increase in androgen-dependent and androgen-independent AR transcriptional activity correlated with an increase in MAGE-A11 and was inhibited by silencing MAGE-A11 expression. MAGE-A11 mediated synergistic AR transcriptional activity in LAPC-4 prostate cancer cells. The ability of MAGE-A11 to rescue transcriptional activity of complementary inactive AR mutants and promote coimmunoprecipitation between unlike forms of AR suggests that MAGE-A11 links transcriptionally active AR dimers. A model for the AR·MAGE-A11 multidimeric complex is proposed in which one AR FXXLF motif of the AR dimer engages in the androgen-dependent AR NH(2)- and carboxyl-terminal interaction, whereas the second FXXLF motif region of the AR dimer interacts with dimeric MAGE-A11. The AR·MAGE-A11 multidimeric complex accounts for the dual functions of the AR FXXLF motif in the androgen-dependent AR NH(2)- and carboxyl-terminal interaction and binding MAGE-A11 and for synergy between reported AR splice variants and full-length AR. We conclude that the increased expression of MAGE-A11 in castration-recurrent prostate cancer, which is enhanced by cyclic AMP signaling, increases AR-dependent growth of prostate cancer by MAGE-A11 forming a molecular bridge between transcriptionally active AR dimers.


Assuntos
Antígenos de Neoplasias/genética , Melanoma/genética , Proteínas de Neoplasias/genética , Neoplasias da Próstata/genética , Receptores Androgênicos/genética , Ativação Transcricional , Motivos de Aminoácidos , Animais , Antígenos de Neoplasias/metabolismo , Sítios de Ligação , Células COS , Chlorocebus aethiops , AMP Cíclico/metabolismo , Humanos , Masculino , Melanoma/metabolismo , Melanoma/patologia , Proteínas de Neoplasias/metabolismo , Plasmídeos , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Ligação Proteica , Multimerização Proteica , Receptores Androgênicos/metabolismo , Transcrição Gênica , Transfecção , Células Tumorais Cultivadas
4.
J Biol Chem ; 287(14): 10905-15, 2012 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-22334658

RESUMO

Naturally occurring germ line mutations in the X-linked human androgen receptor (AR) gene cause incomplete masculinization of the external genitalia by disrupting AR function in males with androgen insensitivity syndrome. Almost all AR missense mutations that cause androgen insensitivity syndrome are located in the highly structured DNA and ligand binding domains. In this report we investigate the functional defect associated with an AR exon 1 missense mutation, R405S, that caused partial androgen insensitivity. The 46,XX heterozygous maternal carrier had a wild-type Arg-405 CGC allele but transmitted an AGC mutant allele coding for Ser-405. At birth, the 46,XY proband had a bifid scrotum, hypospadias, and micropenis consistent with clinical stage 3 partial androgen insensitivity. Androgen-dependent transcriptional activity of AR-R405S expressed in CV1 cells was less than wild-type AR and refractory in androgen-dependent AR NH(2)- and carboxyl interaction transcription assays that depend on the coregulator effects of melanoma antigen-A11. This mutation created a Ser-405 phosphorylation site evident by the gel migration of an AR-R405S NH(2)-terminal fragment as a double band that converted to the wild-type single band after treatment with λ-phosphatase. Detrimental effects of the R405S mutation were related to the proximity of the AR WXXLF motif (433)WHTLF(437) required for melanoma antigen-A11 and p300 to stimulate transcriptional activity associated with the AR NH(2)- and carboxyl-terminal interaction. We conclude that the coregulator effects of melanoma antigen-A11 on the AR NH(2)- and carboxyl-terminal interaction amplify the androgen-dependent transcriptional response to p300 required for normal human male sex development in utero.


Assuntos
Síndrome de Resistência a Andrógenos/genética , Antígenos de Neoplasias/metabolismo , Éxons/genética , Mutação de Sentido Incorreto , Proteínas de Neoplasias/metabolismo , Receptores Androgênicos/química , Receptores Androgênicos/metabolismo , Ativação Transcricional/genética , Motivos de Aminoácidos , Síndrome de Resistência a Andrógenos/metabolismo , Sequência de Bases , Sítios de Ligação , Proteína p300 Associada a E1A/metabolismo , Feminino , Humanos , Masculino , Fenótipo , Fosforilação/genética , Receptores Androgênicos/genética
5.
J Biol Chem ; 287(41): 34809-24, 2012 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-22891251

RESUMO

Progesterone acting through the progesterone receptor (PR) and its coregulators prepares the human endometrium for receptivity to embryo implantation and maintains pregnancy. The menstrual cycle-dependent expression of melanoma antigen-A11 (MAGE-11) in the mid-secretory human endometrium suggested a novel function in human PR signaling. Here we show that MAGE-11 is an isoform-specific coregulator responsible for the greater transcriptional activity of human PR-B relative to PR-A. PR was recruited to progesterone response regions of progesterone-regulated FK506-binding protein 5 (FKBP5) immunophilin and small Ras family G protein cell growth inhibitor RASD1 genes. Expression of MAGE-11 lentivirus shRNA in human endometrial Ishikawa cells expressing PR-B showed that MAGE-11 is required for isoform-specific PR-B up-regulation of FKBP5. In contrast, MAGE-11 was not required for progesterone up-regulation of RASD1 in endometrial cells expressing the PR-A/B heterodimer. Target gene specificity of PR-B depended on the synergistic actions of MAGE-11 and p300 mediated by the unique PR-B NH(2)-terminal (110)LLXXVLXXLL(119) motif that interacts with the MAGE-11 F-box region in a phosphorylation- and ubiquitinylation-dependent manner. A progesterone-dependent mechanism is proposed in which MAGE-11 and p300 increase PR-B up-regulation of the FKBP5 gene. MAGE-11 down-regulates PR-B, similar to the effects of progesterone, and interacts with FKBP5 to stabilize a complex with PR-B. We conclude that the coregulator function of MAGE-11 extends to isoform-specific regulation of PR-B during the cyclic development of the human endometrium.


Assuntos
Antígenos de Neoplasias/metabolismo , Endométrio/metabolismo , Proteínas de Neoplasias/metabolismo , Gravidez/fisiologia , Receptores de Progesterona/metabolismo , Proteínas de Ligação a Tacrolimo/biossíntese , Ativação Transcricional/fisiologia , Adolescente , Adulto , Motivos de Aminoácidos , Animais , Antígenos de Neoplasias/genética , Células COS , Linhagem Celular Tumoral , Chlorocebus aethiops , Regulação para Baixo/fisiologia , Implantação do Embrião/fisiologia , Endométrio/citologia , Feminino , Humanos , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Proteínas de Neoplasias/genética , Multimerização Proteica/fisiologia , Estrutura Terciária de Proteína , Receptores de Progesterona/genética , Elementos de Resposta/fisiologia , Proteínas de Ligação a Tacrolimo/genética , Regulação para Cima/fisiologia , Proteínas ras/biossíntese , Proteínas ras/genética
6.
J Biol Chem ; 286(34): 29951-63, 2011 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-21730049

RESUMO

Male sex development and growth occur in response to high affinity androgen binding to the androgen receptor (AR). In contrast to complete amino acid sequence conservation in the AR DNA and ligand binding domains among mammals, a primate-specific difference in the AR NH(2)-terminal region that regulates the NH(2)- and carboxyl-terminal (N/C) interaction enables direct binding to melanoma antigen-A11 (MAGE-11), an AR coregulator that is also primate-specific. Human, mouse, and rat AR share the same NH(2)-terminal (23)FQNLF(27) sequence that mediates the androgen-dependent N/C interaction. However, the mouse and rat AR FXXLF motif is flanked by Ala(33) that evolved to Val(33) in primates. Human AR Val(33) was required to interact directly with MAGE-11 and for the inhibitory effect of the AR N/C interaction on activation function 2 that was relieved by MAGE-11. The functional importance of MAGE-11 was indicated by decreased human AR regulation of an androgen-dependent endogenous gene using lentivirus short hairpin RNAs and by the greater transcriptional strength of human compared with mouse AR. MAGE-11 increased progesterone and glucocorticoid receptor activity independently of binding an FXXLF motif by interacting with p300 and p160 coactivators. We conclude that the coevolution of the AR NH(2)-terminal sequence and MAGE-11 expression among primates provides increased regulatory control over activation domain dominance. Primate-specific expression of MAGE-11 results in greater steroid receptor transcriptional activity through direct interactions with the human AR FXXLF motif region and indirectly through steroid receptor-associated p300 and p160 coactivators.


Assuntos
Antígenos de Neoplasias/metabolismo , Evolução Molecular , Regulação da Expressão Gênica/fisiologia , Proteínas de Neoplasias/metabolismo , Receptores Androgênicos/metabolismo , Transcrição Gênica/fisiologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Antígenos de Neoplasias/genética , Células COS , Chlorocebus aethiops , Células HeLa , Humanos , Masculino , Camundongos , Proteínas de Neoplasias/genética , Estrutura Terciária de Proteína , Ratos , Receptores Androgênicos/genética , Especificidade da Espécie , Fatores de Transcrição de p300-CBP/genética , Fatores de Transcrição de p300-CBP/metabolismo
7.
J Biol Chem ; 285(28): 21824-36, 2010 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-20448036

RESUMO

Androgen receptor (AR)-mediated gene regulation involves interactions with coregulatory proteins that include the melanoma antigen gene protein-A11 (MAGE-11). To understand the functional significance of sequence similarity between MAGE-11 and the adenovirus early protein E1A, we determined whether MAGE-11 contributes to AR transcriptional activity through an interaction with p300, a potent and ubiquitous transcriptional regulator. Here, we report that MAGE-11 interacts with the NH(2)-terminal region of p300 through the MAGE-11 MXXIF motif (185)MXXIF(189), with transcriptional activity depending on the MAGE-11 F-box and MAPK phosphorylation. The MAGE-11- and p300-dependent increase in AR transactivation required the NH(2)-terminal regions of AR and p300, p300 acetyltransferase activity, and the AR FXXLF motif (23)FQNLF(27) interaction with MAGE-11. MAGE-11 linked AR to p300 and the p160 coactivator, transcriptional intermediary protein 2 (TIF2). The p300 NH(2)-terminal FXXLF motif (33)FGSLF(37) was required for transcriptional activation by TIF2. Increased expression of p300 decreased the ubiquitinylation of MAGE-11 and transiently increased endogenous MAGE-11 levels. Autoacetylation of p300 and decreased acetylation of TIF2 were evident in the MAGE-11, p300, and TIF2 complex. The studies suggest that MAGE-11 links NH(2)-terminal domains of AR and p300 to promote transcriptional synergy through a cadre of FXXLF-related interacting motifs.


Assuntos
Antígenos de Neoplasias/metabolismo , Proteína p300 Associada a E1A/metabolismo , Proteínas de Neoplasias/metabolismo , Motivos de Aminoácidos , Androgênios/metabolismo , Animais , Células COS , Chlorocebus aethiops , Células HeLa , Humanos , Modelos Biológicos , Fosforilação , Receptores Androgênicos/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores de Esteroides/metabolismo , Transcrição Gênica , Técnicas do Sistema de Duplo-Híbrido
8.
Cancer Prev Res (Phila) ; 7(2): 199-210, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24322659

RESUMO

Metformin is an oral biguanide used for type II diabetes. Epidemiologic studies suggest a link between metformin use and reduced risk of breast and other types of cancers. ErbB2-expressing breast cancer is a subgroup of tumors with poor prognosis. Previous studies demonstrated that metformin is a potent inhibitor of ErbB2-overexpressing breast cancer cells; metformin treatment extends the life span and impedes mammary tumor development in ErbB2 transgenic mice in vivo. However, the mechanisms of metformin associated antitumor activity, especially in prevention models, remain unclear. We report here for the first time that systemic administration of metformin selectively inhibits CD61(high)/CD49f(high) subpopulation, a group of tumor-initiating cells (TIC) of mouse mammary tumor virus (MMTV)-ErbB2 mammary tumors, in preneoplastic mammary glands. Metformin also inhibited CD61(high)/CD49f(high) subpopulation in MMTV-ErbB2 tumor-derived cells, which was correlated with their compromised tumor initiation/development in a syngeneic tumor graft model. Molecular analysis indicated that metformin induced downregulation of ErbB2 and EGFR expression and inhibited the phosphorylation of ErbB family members, insulin-like growth factor-1R, AKT, mTOR, and STAT3 in vivo. In vitro data indicate that low doses of metformin inhibited the self-renewal/proliferation of cancer stem cells (CSC)/TICs in ErbB2-overexpressing breast cancer cells. We further demonstrated that the expression and activation of ErbB2 were preferentially increased in CSC/TIC-enriched tumorsphere cells, which promoted their self-renewal/proliferation and rendered them more sensitive to metformin. Our results, especially the in vivo data, provide fundamental support for developing metformin-mediated preventive strategies targeting ErbB2-associated carcinogenesis.


Assuntos
Genes erbB-2 , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/patologia , Metformina/farmacologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Animais , Células Cultivadas , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Integrina alfa6/metabolismo , Integrina beta3/metabolismo , Camundongos , Camundongos Transgênicos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Especificidade de Órgãos/efeitos dos fármacos
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