The myelin protein PMP2 is regulated by SOX10 and drives melanoma cell invasion

The transcription factor SRY(sex related protein-Y)-box10 (SOX10) plays a key role in the development of melanocytes and peripheral glial cells from neural crest precursors. Recently, we and other groups found SOX10 to be involved in melanoma initiation, proliferation, invasion, and survival. However, specific mediators which impart the oncogenic role of SOX10 in melanoma remain widely unknown. To identify potential target genes of SOX10, we performed RNA sequencing to analyze genome-wide expression alterations after ectopic expression of SOX10. Among nine genes differentially regulated by SOX10, only peripheral myelin protein 2 (PMP2) was found upregulated in several other melanoma cell lines. PMP2 is one of the most abundant myelin proteins in glial cells and is necessary for the formation and maintenance of the myelin sheath. We detected PMP2 expression in a subset of human melanoma cell lines while it was absent in human melanocytes and fibroblasts. Direct binding of SOX10 to the PMP2 promoter was shown by chromatin immunoprecipitation and electrophoretic shift assay. In three-dimensional spheroid assays, we found that PMP2 overexpression increased melanoma cell invasion. In conclusion, we identified PMP2 as target gene of SOX10 and propose a novel role for PMP2 in melanoma cell invasion. Overall design: RNA sequencing was performed with 1205Lu metastatic melanoma cells transiently transfected with a vector for SOX10 overexpression (pCMV6-SOX10) or a control vector (pCMV6) in three biological replicates.

转录因子SRY（sex-related protein-Y）框蛋白10（SOX10）在神经嵴前体细胞分化为黑素细胞与外周神经胶质细胞的过程中发挥关键调控作用。近期，本团队与其他研究小组均发现，SOX10参与黑色素瘤的发生、增殖、侵袭及存活调控。但目前介导SOX10在黑色素瘤中发挥致癌功能的具体分子介质仍未明确。为鉴定SOX10的潜在靶基因，我们通过RNA测序（RNA-seq）分析了异位表达SOX10后全基因组的表达谱变化。在受SOX10差异调控的9个基因中，仅外周髓鞘蛋白2（PMP2）在多株其他黑色素瘤细胞系中呈现上调表达。PMP2是胶质细胞中丰度最高的髓鞘蛋白之一，对髓鞘的形成与维持具有不可或缺的作用。我们在部分人黑色素瘤细胞系中检测到PMP2的表达，而在人黑素细胞和成纤维细胞中未检测到该蛋白的表达。染色质免疫共沉淀（chromatin immunoprecipitation, ChIP）与电泳迁移率变动分析（electrophoretic mobility shift assay, EMSA）证实，SOX10可直接结合PMP2的启动子区域。在三维球体侵袭实验中，我们发现过表达PMP2可增强黑色素瘤细胞的侵袭能力。综上，本研究鉴定出PMP2为SOX10的靶基因，并提出PMP2在黑色素瘤细胞侵袭中具有全新的调控功能。整体实验设计：以1205Lu转移性黑色素瘤细胞为研究模型，将其分别瞬时转染SOX10过表达载体（pCMV6-SOX10）与空载对照载体（pCMV6），设置3次生物学重复，随后开展RNA测序。