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. Author manuscript; available in PMC: 2010 Nov 12.
Published in final edited form as: Pigment Cell Melanoma Res. 2010 Jan 22;23(2):225–237. doi: 10.1111/j.1755-148X.2010.00667.x

Figure 6.

Figure 6

PAX3 and SOX10 activate MET expression either directly, or directly and indirectly, in melanoma cells. (A,B,C) Inhibition of both PAX3 and SOX10 protein expression reduces MITF protein levels in SK-MEL23 but not in SK-MEL28 melanoma cells. Western analysis of cells transfected with either scrambled siRNA (lanes 1,3) or gene specific siRNA (lanes 2,4). Graph shown in (B) is the quantified densitometry readings of the western analysis of (A), lanes 1 and 2, and graph shown in (C) is densitometry of lanes 3 and 4. In SK-MEL23 cells (B), inhibition of both PAX3 and SOX10 leads to a reduction of PAX3, SOX10, and MITF 52.5%±5.7%, 28.2%±3.7%, and 70.2%±6.8%, respectively. In SK-MEL28 cells (C), inhibition of both PAX3 and SOX10 leads to a reduction of PAX3 (30.0%±4.3%) and SOX10 (7.5%±2.6%), but no significant reduction of MITF (109.1%±3.7%). (D) Western analysis for MET expression in SK-MEL23 cells transfected with either scrambled siRNA (lanes 1,3) or gene specific siRNA (lanes 2,4). These samples are the same as those shown in lanes 1 and 2 of panel A. (E) Comparison of the inhibition of MET protein expression between targeting MITF (bar sets 1,2) and targeting both PAX3 and SOX10 (bar sets 3,4) in SK-MEL23 cells. Bar sets 1 and 2 show densitometry reading of western analyses shown in Figure 4D,E (lanes 1,2) where inhibition of MITF expression (52.3%±2.5% of controls, bar set 1) leads to an inhibition of MET expression of 68.6%±5.9% (bar set 2). Bar sets 3 and 4 show densitometry of the western analysis shown in (D), where inhibition of both PAX3 and SOX10 expression lead to a reduction of MITF (70.2%±6.8% of controls, bar set 3) and MET (29.6%±9.1%, bar set 4) protein expression. (F) A model for direct and indirect upstream regulation of MET by PAX3 and SOX10. PAX3 and SOX10 can bind directly to upstream enhancer elements in the MET gene locus (arrow 1), or can work through an indirect pathway (arrow 2), where PAX3 and SOX10 regulates the expression of MITF, and MITF with or without SOX10 can activate MET expression.