RESUMO
Phosphoinositide (PI) 3-kinases have been shown to have critical roles in signal transduction, cell transformation and intracellular protein trafficking. Reverse-transcription polymerase chain reaction methods, using degenerate primers derived from the lipid kinase consensus region, were utilised to identify PI 3-kinases in the normal human breast. Here we report the cDNA cloning of a novel human PI 3-kinase isoform, HsC2-PI3K. This PI 3-kinase is most closely related to the recently described C2 domain-containing family of PI 3-kinases which includes Drosophila PI3K_68D/cpk and murine cpk-m/p170. Sequence analysis suggests that HsC2-PI3K is a second distinct mammalian member of the C2 domain-containing PI 3-kinase family. Northern blot analysis of human tissues indicates that HsC2-PI3K is widely expressed. Fluorescence in situ hybridisation has mapped HsC2-PI3K to chromosome 1q32.
Assuntos
Fosfotransferases (Aceptor do Grupo Álcool)/genética , Sequência de Aminoácidos , Mama/enzimologia , Mapeamento Cromossômico , Clonagem Molecular , DNA Complementar/química , Feminino , Humanos , Dados de Sequência Molecular , Fosfatidilinositol 3-Quinases , Conformação Proteica , Alinhamento de Sequência , Transdução de Sinais , Distribuição TecidualRESUMO
WNT-2 is a secreted polypeptide with mitogenic effects in murine mammary epithelial cells, but its role in human cancer is unknown. Using RNase protection analysis of primary cell preparations and in situ hybridization analysis, we report that WNT-2 is expressed at low levels in normal human breast fibroblasts but not in epithelial cells. WNT-2 was found to be expressed at high levels in both the epithelium and stroma of 5 of 11 infiltrating carcinomas and 2 of 6 fibroadenomas. The high level of WNT-2 expression in tumor epithelium suggests that tumorigenesis may involve the ectopic expression of WNT-2 and the creation of an autocrine Wnt signaling loop.
Assuntos
Neoplasias da Mama/genética , Mama/metabolismo , Carcinoma Ductal de Mama/genética , Fibroadenoma/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Neoplasias/biossíntese , Proteínas Proto-Oncogênicas/biossíntese , Mama/citologia , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Tecido Conjuntivo/metabolismo , Epitélio/metabolismo , Feminino , Fibroadenoma/patologia , Fibroblastos/metabolismo , Humanos , Hibridização In Situ , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogênicas/genética , Transdução de Sinais/fisiologia , Proteína Wnt2RESUMO
Expression of the Msx-1 and Msx-2 homeobox genes have been shown to be coordinately regulated with the Bmp-2 and Bmp-4 ligands in a variety of developing tissues. Here we report that transcripts from all four genes are developmentally regulated during both foetal and postnatal mammary gland development. The location and time-course of the Bmp and Msx expression point to a role for Msx and Bmp gene products in the control of epithelial-mesenchymal interactions. Expression of Msx-2, but not Msx-1, Bmp-2 or Bmp-4 was decreased following ovariectomy, while expression of the human Msx-2 homologue was regulated by 17beta-oestradiol in the MCF-7 breast cancer cell line. The regulation of Msx-2 expression by oestrogen raises the possibility that hormonal regulation of mammary development is mediated through the control of epithelial-mesenchymal interactions.
Assuntos
Proteínas Morfogenéticas Ósseas/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Homeodomínio/genética , Glândulas Mamárias Animais/crescimento & desenvolvimento , Fatores de Transcrição , Animais , Northern Blotting , Estradiol/farmacologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Humanos , Hibridização In Situ , Fator de Transcrição MSX1 , Glândulas Mamárias Animais/embriologia , Glândulas Mamárias Animais/metabolismo , Camundongos , Camundongos Endogâmicos , Camundongos Transgênicos , Morfogênese , Ovariectomia , Gravidez , RNA Antissenso/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Células Tumorais CultivadasRESUMO
Ectopic expression of Wnt-1 in the mammary epithelium causes hyperplasias and increases the frequency of tumour formation. Other members of the Wnt gene family are naturally expressed in the breast and are thought to be involved in controlling mammary gland development. Using Northern and in-situ hybridisation, differential expression of Wnt-2, Wnt-4, Wnt-5a, Wnt-5b, Wnt-6 and Wnt-7b in epithelial and mesenchymal compartments was observed. Complex patterns of Wnt expression were found during the ductal, lobulo-alveolar and involution phases of development. Finally, Wnt-2, Wnt-4 and Wnt-5b were shown to be regulated by ovarian hormones. These results suggest that Wnt genes have non-redundant roles in breast development and may be involved in the hormonal regulation of mammary growth.
