Ligand-activated BMP signaling inhibits cell differentiation and death to promote melanoma
Arvind M. Venkatesan, … , Michael Green, Craig J. Ceol
Arvind M. Venkatesan, … , Michael Green, Craig J. Ceol
Published December 4, 2017
Citation Information: J Clin Invest. 2018;128(1):294-308. https://doi.org/10.1172/JCI92513.
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Research Article Development Oncology

Ligand-activated BMP signaling inhibits cell differentiation and death to promote melanoma

Abstract

Oncogenomic studies indicate that copy number variation (CNV) alters genes involved in tumor progression; however, identification of specific driver genes affected by CNV has been difficult, as these rearrangements are often contained in large chromosomal intervals among several bystander genes. Here, we addressed this problem and identified a CNV-targeted oncogene by performing comparative oncogenomics of human and zebrafish melanomas. We determined that the gene encoding growth differentiation factor 6 (GDF6), which is the ligand for the BMP family, is recurrently amplified and transcriptionally upregulated in melanoma. GDF6-induced BMP signaling maintained a trunk neural crest gene signature in melanomas. Additionally, GDF6 repressed the melanocyte differentiation gene MITF and the proapoptotic factor SOX9, thereby preventing differentiation, inhibiting cell death, and promoting tumor growth. GDF6 was specifically expressed in melanomas but not melanocytes. Moreover, GDF6 expression levels in melanomas were inversely correlated with patient survival. Our study has identified a fundamental role for GDF6 and BMP signaling in governing an embryonic cell gene signature to promote melanoma progression, thus providing potential opportunities for targeted therapy to treat GDF6-positive cancers.

Authors

Arvind M. Venkatesan, Rajesh Vyas, Alec K. Gramann, Karen Dresser, Sharvari Gujja, Sanchita Bhatnagar, Sagar Chhangawala, Camilla Borges Ferreira Gomes, Hualin Simon Xi, Christine G. Lian, Yariv Houvras, Yvonne J. K. Edwards, April Deng, Michael Green, Craig J. Ceol

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Figure 2

GDF6 modulation alters melanoma growth.

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GDF6 modulation alters melanoma growth. (A) Melanoma-free survival curv...
(A) Melanoma-free survival curves for Tg(mitfa:BRAFV600E);p53(lf);mitfa(lf) zebrafish injected with miniCoopR-gdf6b or miniCoopR-EGFP. Statistical analysis was performed with a Wilcoxon rank-sum test. (B) Melanoma-free survival curves for Tg(mitfa:BRAFV600E);p53(lf) and Tg(mitfa:BRAFV600E);p53(lf);gdf6a(lf) zebrafish. Statistical analysis was performed with a Wilcoxon rank-sum test. (C) Immunoblot showing expression and quantification of GDF6 protein levels (relative to GDF6 protein in A375 melanoma cells) in melanoma cell lines. GAPDH was used as a loading control. Copy number values of the GDF6 locus in the different melanoma cell lines obtained from the COSMIC database (http://cancer.sanger.ac.uk/cosmic) are shown. (D) Immunoblots showing expression of GDF6 and GAPDH in A375 melanoma cells and M14 melanoma cells overexpressing GDF6. (E) Tumor formation in mice injected with A375 cells and M14 cells overexpressing GDF6 or empty vector control (1 × 106 cells were injected per mouse). Error bars represent the mean ± SEM. n = 3. (F) Immunoblots showing expression of GDF6 in A375 cells (top) expressing an shRNA targeting EGFP or 2 independent GDF6-targeted shRNAs and M14 cells (bottom) expressing an shRNA targeting EGFP or the GDF6-targeted shRNA GDF6.1. (G) Colony formation assay with A375 cells (left) expressing an shRNA targeting EGFP or 2 independent GDF6-targeted shRNAs and M14 cells (right) expressing an shRNA targeting EGFP or the GDF6-targeted shRNA GDF6.1. Error bars represent the mean ± SEM. n = 3. (H) Tumor formation in mice injected with A375 cells expressing an shRNA targeting EGFP or 2 independent GDF6-targeted shRNAs and M14 cells expressing an shRNA targeting EGFP or the GDF6-targeted shRNA GDF6.1 (1 × 107 cells were injected per mouse). Error bars represent the mean ± SEM. n = 3. *P < 0.05, **P < 0.01, and ***P < 0.001, by 2-tailed Student’s t test (E and G [right] and H [right]) or 1-way ANOVA with Dunnett’s test (G [left] and H [left]).