In melanoma and other cancers, invasion, epithelial-to-mesenchymal transition, metastasis and cancer stem cell maintenance are regulated by transcription factors including the Snail family. Slug (Snail2) protein generally supports migration and apoptosis resistance. However, its role in melanoma is not completely understood. The present study investigated the transcriptional regulation of the SLUG gene in melanoma. It demonstrated that SLUG is under the control of the Hedgehog/GLI signaling pathway and is activated predominantly by the transcription factor GLI2. The SLUG gene promoter contains a high number of GLI-binding sites. Slug expression is activated by GLI factors in reporter assays and inhibited by GANT61 (GLI inhibitor) and cyclopamine (SMO inhibitor). SLUG mRNA levels are lowered by GANT61 as assessed by reverse transcription-quantitative PCR. Chromatin immunoprecipitation revealed abundant binding of factors GLI1-3 in the four subregions of the proximal SLUG promoter. Notably, melanoma-associated transcription factor (MITF) is an imperfect activator of the SLUG promoter in reporter assays, and downregulation of MITF had no effect on endogenous Slug protein levels. Immunohistochemical analysis confirmed the above findings and showed MITF-negative regions in metastatic melanoma that were positive for GLI2 and Slug. Taken together, the results demonstrated a previously unrecognized transcriptional activation mechanism of the SLUG gene, which may represent its main regulation of expression in melanoma cells.

• Klíčová slova
• GLI family zinc finger, Hedgehog signaling, Slug, melanoma, melanoma-associated transcription factor,
• MeSH
• apoptóza MeSH
• lidé MeSH
• melanom * genetika   MeSH
• proteiny hedgehog * genetika   MeSH
• signální transdukce MeSH
• transkripční faktory genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• proteiny hedgehog * MeSH
• transkripční faktory MeSH

Metastasized malignant melanoma has a poor prognosis because of its intrinsic resistance to chemotherapy and radiotherapy. The central role in the melanoma transcriptional network has the transcription factor MITF (microphthalmia-associated transcription factor). It has been shown recently that the expression of MITF and some of its target genes require the SWI/SNF chromatin remodeling complex. Here we demonstrate that survival of melanoma cells requires functional SWI/SNF complex not only by supporting expression of MITF and its targets and but also by activating expression of prosurvival proteins not directly regulated by MITF. Microarray analysis revealed that besides the MITF-driven genes, expression of proteins like osteopontin, IGF1, TGFß2 and survivin, the factors known to be generally associated with progression of tumors and the antiapoptotic properties, were reduced in acute BRG1-depleted 501mel cells. Western blots and RT-PCR confirmed the microarray findings. These proteins have been verified to be expressed independently of MITF, because MITF depletion did not impair their expression. Because these genes are not regulated by MITF, the data suggests that loss of BRG1-based SWI/SNF complexes negatively affects survival pathways beyond the MITF cascade. Immunohistochemistry showed high expression of both BRM and BRG1 in primary melanomas. Exogenous CDK2, osteopontin, or IGF1 each alone partly relieved the block of proliferation imposed by BRG1 depletion, implicating that more factors, besides the MITF target genes, are involved in melanoma cell survival. Together these results demonstrate an essential role of SWI/SNF for the expression of MITF-dependent and MITF-independent prosurvival factors in melanoma cells and suggest that SWI/SNF may be a potential and effective target in melanoma therapy.

• MeSH
• apoptóza genetika   MeSH
• chromozomální proteiny, nehistonové genetika   metabolismus   MeSH
• cyklin-dependentní kinasa 2 genetika   metabolismus   MeSH
• DNA-helikasy genetika   metabolismus   MeSH
• imunohistochemie MeSH
• inhibitory apoptózy genetika   metabolismus   MeSH
• insulinu podobný růstový faktor I genetika   metabolismus   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• lidé MeSH
• melanom genetika   metabolismus   patologie   MeSH
• nádorové buněčné linie MeSH
• névus genetika   metabolismus   patologie   MeSH
• osteopontin genetika   metabolismus   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• proliferace buněk MeSH
• RNA interference MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
• stanovení celkové genové exprese MeSH
• survivin MeSH
• transformující růstový faktor beta2 genetika   metabolismus   MeSH
• transkripční faktor spojený s mikroftalmií genetika   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• viabilita buněk genetika   MeSH
• western blotting MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• BIRC5 protein, human MeSH Prohlížeč
• CDK2 protein, human MeSH Prohlížeč
• chromozomální proteiny, nehistonové MeSH
• cyklin-dependentní kinasa 2 MeSH
• DNA-helikasy MeSH
• inhibitory apoptózy MeSH
• insulinu podobný růstový faktor I MeSH
• jaderné proteiny MeSH
• MITF protein, human MeSH Prohlížeč
• osteopontin MeSH
• SMARCA2 protein, human MeSH Prohlížeč
• SMARCA4 protein, human MeSH Prohlížeč
• survivin MeSH
• SWI-SNF-B chromatin-remodeling complex MeSH Prohlížeč
• transformující růstový faktor beta2 MeSH
• transkripční faktor spojený s mikroftalmií MeSH
• transkripční faktory MeSH