Figure 6 from p300 KAT Regulates SOX10 Stability and Function in Human Melanoma

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posted on 2024-08-01, 15:20 authored by Aaron Waddell, Nicole Grbic, Kassidy Leibowitz, William Austin Wyant, Sabah Choudhury, Kihyun Park, Marianne Collard, Philip A. Cole, Rhoda M. Alani

p300 KAT activity is essential for the activation of SOX10-repressed EMT markers. A, Diagram depicting the hypothesis that p300 activity is essential for the expression of SOX10-activated genes, but SOX10-repressed genes may also require p300 for their activation. B, Volcano plots of SOX10-repressed genes differentially expressed due to A-485 treatment for IPC-298, CO79, and A375 cells (DEGs defined as FC > |2| and P < 0.05). C, SOX10-repressed genes are enriched for genes involved in the EMT, and similar invasion-related pathways are downregulated by A-485. CAM, cell adhesion molecules; ECM, extracellular matrix. D, Volcano plot of EMT genes differentially expressed due to A-485 treatment for A375 cells. E, Volcano plot of SOX10-regulated EMT genes differentially expressed due to A-485 treatment for A375 cells. F, Volcano plots of genes differentially expressed due to A-485 are shown for various KEGG invasion-related pathways identified in C. Differentially expressed collagen genes are also shown. G, H3K27ac is enriched at the promoters of EMT genes THBS1 and SFRP1 in comparison with a gene desert in invasive 1205Lu cells via ChIP sequencing. H, H3K27ac was confirmed to be enriched at the promoters of THBS1 and SFRP1 in comparison with a gene desert in A375 cells via ChIP-qPCR. I, A-485 decreases H3K27ac enrichment at the promoters of THBS1 and SFRP1, as assessed by ChIP-qPCR. (J) 5 µmol/L A-485 alters the cell morphology of A375 and 1205Lu cells after long-term (12-day) treatment. K, A-485 potently inhibits invasion in A375 and 1205Lu after long-term (12-day) treatment. Representative images of invaded cells are shown on the left, and quantification of invaded cells is shown on the right. *, P < 0.05; **, P < 0.005; ***, P < 0.0005.

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ARTICLE ABSTRACT

SOX10 is a lineage-specific transcription factor critical for melanoma tumor growth; on the other hand, SOX10 loss-of-function drives the emergence of therapy-resistant, invasive melanoma phenotypes. A major challenge has been developing therapeutic strategies targeting SOX10’s role in melanoma proliferation while preventing a concomitant increase in tumor cell invasion. In this study, we report that the lysine acetyltransferase (KAT) EP300 and SOX10 gene loci on chromosome 22 are frequently co-amplified in melanomas, including UV-associated and acral tumors. We further show that p300 KAT activity mediates SOX10 protein stability and that the p300 inhibitor A-485 downregulates SOX10 protein levels in melanoma cells via proteasome-mediated degradation. Additionally, A-485 potently inhibits proliferation of SOX10+ melanoma cells while decreasing invasion in AXLhigh/MITFlow melanoma cells through downregulation of metastasis-related genes. We conclude that the SOX10/p300 axis is critical to melanoma growth and invasion and that inhibition of p300 KAT activity through A-485 may be a worthwhile therapeutic approach for SOX10-reliant tumors. The p300 KAT inhibitor A-485 blocks SOX10-dependent proliferation and SOX10-independent invasion in hard-to-treat melanoma cells.