Departamento de Farmacologia, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.
PLoS One. 2012;7(9):e44800. doi: 10.1371/journal.pone.0044800. Epub 2012 Sep 11.
Metastatic melanoma is a highly aggressive skin cancer and currently resistant to systemic therapy. Melanomas may involve genetic, epigenetic and metabolic abnormalities. Evidence is emerging that epigenetic changes might play a significant role in tumor cell plasticity and metastatic phenotype of melanoma cells.
In this study, we developed a systematic approach to identify genes implicated in melanoma progression. To do this, we used the Affymetrix GeneChip Arrays to screen 34,000 mouse transcripts in melan-a melanocytes, 4C pre-malignant melanocytes, 4C11- non-metastatic and 4C11+ metastatic melanoma cell lines. The genome-wide association studies revealed pathways commonly over-represented in the transition from immortalized to pre-malignant stage, and under-represented in the transition from non-metastatic to metastatic stage. Additionally, the treatment of cells with 10 µM 5-aza-2'-deoxycytidine (5AzaCdR) for 48 hours allowed us to identify genes differentially re-expressed at specific stages of melan-a malignant transformation. Treatment of human primary melanocytes with the demethylating agent 5AzaCdR in combination to the histone deacetylase inhibitor Trichostatin A (TSA) revealed changes on melanocyte morphology and gene expression which could be an indicator of epigenetic flexibility in normal melanocytes. Moreover, changes on gene expression recognized by affecting the melanocyte biology (NDRG2 and VDR), phenotype of metastatic melanoma cells (HSPB1 and SERPINE1) and response to cancer therapy (CTCF, NSD1 and SRC) were found when Mel-2 and/or Mel-3-derived patient metastases were exposed to 5AzaCdR plus TSA treatment. Hierarchical clustering and network analyses in a panel of five patient-derived metastatic melanoma cells showed gene interactions that have never been described in melanomas.
Despite the heterogeneity observed in melanomas, this study demonstrates the utility of our murine melanoma progression model to identify molecular markers commonly perturbed in metastasis. Additionally, the novel gene expression signature identified here may be useful in the future into a model more closely related to translational research.
转移性黑色素瘤是一种高度侵袭性的皮肤癌，目前对全身治疗有抵抗力。黑色素瘤可能涉及遗传、表观遗传和代谢异常。有证据表明，表观遗传变化可能在肿瘤细胞可塑性和黑色素瘤细胞的转移表型中发挥重要作用。
在这项研究中，我们开发了一种系统的方法来确定参与黑色素瘤进展的基因。为此，我们使用 Affymetrix GeneChip Arrays 筛选了 34000 个小鼠转录本，包括 melan-a 黑素细胞、4C 前恶性黑素细胞、4C11-非转移性和 4C11+转移性黑色素瘤细胞系。全基因组关联研究揭示了在从永生化到前恶性阶段的转变中普遍过度表达的途径，以及在从非转移性到转移性阶段的转变中表达不足的途径。此外，用 10µM 5-氮杂-2'-脱氧胞苷（5AzaCdR）处理细胞 48 小时，使我们能够识别在 melan-a 恶性转化的特定阶段差异表达的基因。用去甲基化剂 5AzaCdR 联合组蛋白去乙酰化酶抑制剂 Trichostatin A（TSA）处理人原代黑素细胞，揭示了黑素细胞形态和基因表达的变化，这可能是正常黑素细胞中表观遗传灵活性的一个指标。此外，当 Mel-2 和/或 Mel-3 衍生的患者转移物暴露于 5AzaCdR 加 TSA 处理时，我们发现了影响黑素细胞生物学（NDRG2 和 VDR）、转移性黑色素瘤细胞表型（HSPB1 和 SERPINE1）和癌症治疗反应（CTCF、NSD1 和 SRC）的基因表达变化。在一组五个患者来源的转移性黑色素瘤细胞的层次聚类和网络分析中，显示了从未在黑色素瘤中描述过的基因相互作用。
尽管在黑色素瘤中观察到异质性，但这项研究证明了我们的小鼠黑色素瘤进展模型在识别普遍失调的转移分子标记方面的实用性。此外，这里确定的新基因表达特征可能对未来与转化研究更密切相关的模型有用。
