Inhibition of PAX3 by TGF-β Modulates Melanocyte Viability
ABSTRACT The protein encoded by paired-box homeotic gene 3 (PAX3) is a key regulator of the microphthalmia-associated transcription factor (Mitf) in the melanocyte lineage. Here, we show that PAX3 expression in skin is directly inhibited by TGF-beta/Smads. UV irradiation represses TGF-beta in keratinocytes, and the repression of TGF-beta/Smads upregulates PAX3 in melanocytes, which is associated with a UV-induced melanogenic response and consequent pigmentation. Furthermore, the TGF-beta-PAX3 signaling pathway interacts with the p53-POMC/MSH-MC1R signaling pathway, and both are crucial in melanogenesis. The activation of p53-POMC/MSH-MC1R signaling is required for the UV-induced melanogenic response because PAX3 functions in synergy with SOX10 in a cAMP-response element (CRE)-dependent manner to regulate the transcription of Mitf. This study will provide a rich foundation for further research on skin cancer prevention by enabling us to identify targeted small molecules in the signaling pathways of the UV-induced melanogenic response that are highly likely to induce naturally protective pigmentation.
- SourceAvailable from: Arturo Brunetti
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- "Notably, TGF-β acts as an early tumor suppressor, but functions later as a tumour promoter and a pro-metastatic agent . In normal melanocytes, TGF-β acts as a potent inhibitor of proliferation and differentiation [7,8]; in advanced melanoma, TGF-β favors cell proliferation and dissemination, peri-tumoral angiogenesis, EMT and tumor escape from immune surveillance [9-11]. The mechanism underlying evasion from a cytostatic response to TGF-β in tumor cells remains somewhat elusive. "
ABSTRACT: FKBP51 (FKBP5 Official Symbol) is a large molecular weight component of the family of FK506 binding proteins (FKBP). In recent years, research studies from our laboratory highlighted functions for FKBP51 in the control of apoptosis and melanoma progression. FKBP51 expression correlated with the invasiveness and aggressiveness of melanoma. Since a role for TGF-beta in the enhanced tumorigenic potential of melanoma cells is widely described, we hypothesized a cooperative effect between FKBP51 and TGF-beta in melanoma progression. SAN and A375 melanoma cell lines were utilized for this study. Balb/c IL2gamma NOD SCID served to assess the ability to colonize organs and metastasize of different cell lines, which was evaluated by in vivo imaging. Realtime PCR and western blot served for measurement of mRNA and protein expression, respectively. By comparing the metastatic potential of two melanoma cell lines, namely A375 and SAN, we confirmed that an increased capability to colonize murine organs was associated with increased levels of FKBP51. A375 melanoma cell line expressed FKBP51 mRNA levels 30-fold higher in comparison to the SAN mRNA level and appeared more aggressive than SAN melanoma cell line in an experimental metastasis model. In addition, A375 expressed, more abundantly than SAN, the TGF-beta and the pro angiogenic TGF-beta receptor type III (TbetaRIII) factors. FKBP51 silencing produced a reduction of TGF-beta and TbetaRIII gene expression in A375 cell line, in accordance with previous studies. We found that the inducing effect of TGF-beta on Sparc and Vimentin expression was impaired in condition of FKBP51 depletion, suggesting that FKBP51 is an important cofactor in the TGF-beta signal. Such a hypothesis was supported by co immunoprecipitation assays, showing that FKBP51 interacted with either Smad2,3 and p300. In normal melanocytes, FKBP51 potentiated the effect of TGF-beta on N-cadherin expression and conferred a mesenchymal-like morphology to such round-shaped cells. Overall, our findings show that FKBP51 enhances some pro oncogenic functions of TGF-beta, suggesting that FKBP51-overexpression may help melanoma to take advantage of the tumor promoting activities of the cytokine.01/2014; 3(1):1. DOI:10.1186/2001-1326-3-1
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- "Immunohistochemical staining was performed as described . The immunohistochemical scoring (H score) was determined by multiplying the staining intensity by the percentage of positive tumor cells [25,26]. These primary antibodies were used: anti-p16 （f-12, SC-1661）, anti-p21（C-19, SC397, anti-TSLP (M-20, SC19178), anti-α-smooth muscle actin (α-SMA) (1A4, ab7817), anti-collagen I (ab34710) and anti-Ki67(M-19, SC7846). "
ABSTRACT: Airway remodeling is a repair process that occurs after injury resulting in increased airway hyper-responsiveness in asthma. Thymic stromal lymphopoietin (TSLP), a vital cytokine, plays a critical role in orchestrating, perpetuating and amplifying the inflammatory response in asthma. TSLP is also a critical factor in airway remodeling in asthma. To examine the role of TSLP-induced cellular senescence in airway remodeling of asthma in vitro and in vivo. Cellular senescence and airway remodeling were examined in lung specimens from patients with asthma using immunohischemical analysis. Both small molecule and shRNA approaches that target the senescent signaling pathways were used to explore the role of cellular senescence in TSLP-induced airway remodeling in vitro. Senescence-Associated β-galactosidase (SA-β-Gal) staining, and BrdU assays were used to detect cellular senescence. In addition, the Stat3-targeted inhibitor, WP1066, was evaluated in an asthma mouse model to determine if inhibiting cellular senescence influences airway remodeling in asthma. Activation of cellular senescence as evidenced by checkpoint activation and cell cycle arrest was detected in airway epithelia samples from patients with asthma. Furthermore, TSLP-induced cellular senescence was required for airway remodeling in vitro. In addition, a mouse asthma model indicates that inhibiting cellular senescence blocks airway remodeling and relieves airway resistance. TSLP stimulation can induce cellular senescence during airway remodeling in asthma. Inhibiting the signaling pathways of cellular senescence overcomes TSLP-induced airway remodeling.PLoS ONE 10/2013; 8(10):e77795. DOI:10.1371/journal.pone.0077795 · 3.23 Impact Factor
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- "In normal melanocytes, TGF-β acts as a potent inhibitor of proliferation and differentiation14. TGF-β1 represses the paired-box transcription factor PAX3, which cooperates with the homeobox transcription factor SOX10 to induce melanocyte differentiation15. TGF-β may also interfere with melanocyte maturation by inhibiting of microphtalmia transcription factor (M-MITF), a master transcription factor specific of the melanocytic lineage that controls cell survival, migration and differentiation16. "
ABSTRACT: Transforming growth factor-β (TGF-β) is a pleiotropic growth factor with broad tissue distribution that plays critical roles during embryonic development, normal tissue homeostasis, and cancer. While its cytostatic activity on normal epithelial cells initially defined TGF-β signaling as a tumor suppressor pathway, there is ample evidence indicating that TGF-β is a potent pro-tumorigenic agent, acting via autocrine and paracrine mechanisms to promote peri-tumoral angiogenesis, together with tumor cell migration, immune escape, and dissemination to metastatic sites. This review summarizes the current knowledge on the implication of TGF-β signaling in melanoma.Annals of Dermatology 05/2013; 25(2):135-144. DOI:10.5021/ad.2013.25.2.135 · 0.95 Impact Factor