RESUMO
Data emerged from the last 20 years of basic research on tumor antigens positioned the type I MAGE (Melanoma Antigen GEnes - I or MAGE-I) family as cancer driver factors. MAGE-I gene expression is mainly restricted to normal reproductive tissues. However, abnormal re-expression in cancer unbalances the cell status towards enhanced oncogenic activity or reduced tumor suppression. Anomalous MAGE-I gene re-expression in cancer is attributed to altered epigenetic-mediated chromatin silencing. Still, emerging data indicate that MAGE-I can be regulated at protein level. Results from different laboratories suggest that after its anomalous re-expression, specific MAGE-I proteins can be regulated by well-known signaling pathways or key cellular processes that finally potentiate the cancer cell phenotype. Thus, MAGE-I proteins both regulate and are regulated by cancer-related pathways. Here, we present an updated review highlighting the recent findings on the regulation of MAGE-I by oncogenic pathways and the potential consequences in the tumor cell behavior.
Assuntos
Melanoma , Proteínas de Neoplasias , Humanos , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Antígenos de Neoplasias/genéticaRESUMO
Oral Squamous Cell Carcinoma (OSCC) is the most common malignant cancer affecting the oral cavity. It is characterized by high morbidity and very few therapeutic options. Angiotensin (Ang)-(1-7) is a biologically active heptapeptide, generated predominantly from AngII (Ang-(1-8)) by the enzymatic activity of angiotensin-converting enzyme 2 (ACE 2). Previous studies have shown that Ang-(1-7) counterbalances AngII pro-tumorigenic actions in different pathophysiological settings, exhibiting antiproliferative and anti-angiogenic properties in cancer cells. However, the prevailing effects of Ang-(1-7) in the oral epithelium have not been established in vivo. Here, we used an inducible oral-specific mouse model, where the expression of a tamoxifen-inducible Cre recombinase (CreERtam), which is under the control of the cytokeratin 14 promoter (K14-CreERtam), induces the expression of the K-ras oncogenic variant KrasG12D (LSLK-rasG12D). These mice develop highly proliferative squamous papilloma in the oral cavity and hyperplasia exclusively in oral mucosa within one month after tamoxifen treatment. Ang-(1-7) treated mice showed a reduced papilloma development accompanied by a significant reduction in cell proliferation and a decrease in pS6 positivity, the most downstream target of the PI3K/Akt/mTOR signaling route in oral papilloma. These results suggest that Ang-(1-7) may be a novel therapeutic target for OSCC.
Assuntos
Carcinoma de Células Escamosas , Neoplasias Bucais , Papiloma , Infecções por Papillomavirus , Angiotensina I/farmacologia , Animais , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/patologia , Camundongos , Camundongos Transgênicos , Neoplasias Bucais/tratamento farmacológico , Papiloma/tratamento farmacológico , Papiloma/patologia , Papiloma/prevenção & controle , Infecções por Papillomavirus/tratamento farmacológico , Fragmentos de Peptídeos , Fosfatidilinositol 3-Quinases/metabolismo , Tamoxifeno/uso terapêuticoRESUMO
Normal-to-tumor cell transition is accompanied by changes in gene expression and signal transduction that turns the balance toward cancer-cell phenotype, eluding by different mechanisms, the response of tumor-suppressor genes. Here, we observed that MageC2, a MAGE-I protein able to regulate the p53 tumor-suppressor, is accumulated upon MEK/ERK MAPK activation. Overexpression of H-RasV12 oncogene causes an increase in MageC2 protein that is prevented by pharmacologic inhibition of MEK. Similarly, decrease in MageC2 protein levels is shown in A375 melanoma cells (which harbor B-RafV600E oncogenic mutation) treated with MEK inhibitors. MageC2 protein levels decrease when p14ARF is expressed, causing an Mdm2-independent upregulation of p53 transactivation. However, MageC2 is refractory to p14ARF-driven downregulation when H-RasV12 is co-expressed. Using MageC2 knockout A375 cells generated by CRISPR/CAS9 technology, we demonstrated the relevance of MageC2 protein in reducing p53 transcriptional activity in cells containing hyperactive MEK/ERK signaling. Furthermore, gene expression analysis performed in cancer-genomic databases, supports the correlation of reduced p53 transcriptional activity and high MageC2 expression, in melanoma cells containing Ras or B-Raf driver mutations. Data presented here suggest that MageC2 can be a functional target of the oncogenic MEK/ERK pathway to regulate p53.
Assuntos
Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Melanoma/metabolismo , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Antígenos de Neoplasias/química , Linhagem Celular Tumoral , Inibidor p16 de Quinase Dependente de Ciclina/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Regulação Neoplásica da Expressão Gênica , Técnicas de Inativação de Genes , Células HEK293 , Humanos , Sistema de Sinalização das MAP Quinases , Melanoma/genética , Camundongos , Proteínas de Neoplasias/química , Estabilidade Proteica , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Ativação TranscricionalRESUMO
Angiotensin (Ang) II, the main effector peptide of the renin-angiotensin system, has been implicated in multiple aspects of cancer progression such as proliferation, migration, invasion, angiogenesis and metastasis. Ang-(1-7), is a biologically active heptapeptide, generated predominantly from AngII by the enzymatic activity of angiotensin converting enzyme 2. Previous studies have shown that Ang-(1-7) counterbalances AngII actions in different pathophysiological settings. In this study, we have analysed the impact of Ang-(1-7) on AngII-induced pro-tumorigenic features on normal murine mammary epithelial cells NMuMG and breast cancer cells MDA-MB-231. AngII stimulated the activation of the survival factor AKT in NMuMG cells mainly through the AT1 receptor. This PI3K/AKT pathway activation also promoted epithelial-mesenchymal transition (EMT). Concomitant treatment of NMuMG cells with AngII and Ang-(1-7) completely abolished EMT features induced by AngII. Furthermore, Ang-(1-7) abrogated AngII induced migration and invasion of the MDA-MB-231 cells as well as pro-angiogenic events such as the stimulation of MMP-9 activity and VEGF expression. Together, these results demonstrate for the first time that Ang-(1-7) counteracts tumor aggressive signals stimulated by AngII in breast cancer cells emerging the peptide as a potential therapy to prevent breast cancer progression.