Basu Reetobrata, Kulkarni Prateek, Qian Yanrong, Walsh Christopher, Arora Pranay, Davis Emily, Duran-Ortiz Silvana, Funk Kevin, Ibarra Diego, Kruse Colin, Mathes Samuel, McHugh Todd, Brittain Alison, Berryman Darlene E, List Edward O, Okada Shigeru, Kopchick John J
Edison Biotechnology Institute, Ohio University, Athens, OH 45701, USA.
Molecular and Cellular Biology (MCB) Program, Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
Cancers (Basel). 2019 Sep 12;11(9):1352. doi: 10.3390/cancers11091352.
Growth hormone (GH) facilitates therapy resistance in the cancers of breast, colon, endometrium, and melanoma. The GH-stimulated pathways responsible for this resistance were identified as suppression of apoptosis, induction of epithelial-to-mesenchymal transition (EMT), and upregulated drug efflux by increased expression of ATP-binding cassette containing multidrug efflux pumps (ABC-transporters). In extremely drug-resistant melanoma, ABC-transporters have also been reported to mediate drug sequestration in intracellular melanosomes, thereby reducing drug efficacy. Melanocyte-inducing transcription factor (MITF) is the master regulator of melanocyte and melanoma cell fate as well as the melanosomal machinery. MITF targets such as the oncogene MET, as well as MITF-mediated processes such as resistance to radiation therapy, are both known to be upregulated by GH. Therefore, we chose to query the direct effects of GH on MITF expression and activity towards conferring chemoresistance in melanoma. Here, we demonstrate that GH significantly upregulates MITF as well as the MITF target genes following treatment with multiple anticancer drug treatments such as chemotherapy, BRAF-inhibitors, as well as tyrosine-kinase inhibitors. GH action also upregulated MITF-regulated processes such as melanogenesis and tyrosinase activity. Significant elevation in MITF and MITF target gene expression was also observed in mouse B16F10 melanoma cells and xenografts in bovine GH transgenic (bGH) mice compared to wild-type littermates. Through pathway inhibitor analysis we identified that both the JAK2-STAT5 and SRC activities were critical for the observed effects. Additionally, a retrospective analysis of gene expression data from GTEx, NCI60, CCLE, and TCGA databases corroborated our observed correlation of MITF function and GH action. Therefore, we present in vitro, in vivo, and in silico evidence which strongly implicates the GH-GHR axis in inducing chemoresistance in human melanoma by driving MITF-regulated and ABC-transporter-mediated drug clearance pathways.
生长激素（GH）促进乳腺癌、结肠癌、子宫内膜癌和黑色素瘤对治疗产生抗性。导致这种抗性的GH刺激途径被确定为抑制细胞凋亡、诱导上皮-间质转化（EMT）以及通过增加含多药外排泵的ATP结合盒（ABC转运蛋白）的表达来上调药物外排。在极具耐药性的黑色素瘤中，也有报道称ABC转运蛋白介导细胞内黑素小体中的药物隔离，从而降低药物疗效。黑素细胞诱导转录因子（MITF）是黑素细胞和黑色素瘤细胞命运以及黑素小体机制的主要调节因子。已知GH会上调MITF的靶标，如癌基因MET，以及MITF介导的过程，如对放射治疗的抗性。因此，我们选择研究GH对MITF表达的直接影响以及其在黑色素瘤中赋予化学抗性的活性。在这里，我们证明，在用多种抗癌药物治疗（如化疗、BRAF抑制剂以及酪氨酸激酶抑制剂）后，GH会显著上调MITF以及MITF靶基因。GH的作用还上调了MITF调节的过程，如黑色素生成和酪氨酸酶活性。与野生型同窝小鼠相比，在牛生长激素转基因（bGH）小鼠的小鼠B16F10黑色素瘤细胞和异种移植瘤中也观察到MITF和MITF靶基因表达显著升高。通过通路抑制剂分析，我们确定JAK2-STAT5和SRC活性对于观察到的效应都至关重要。此外，对来自GTEx、NCI60、CCLE和TCGA数据库的基因表达数据进行的回顾性分析证实了我们观察到的MITF功能与GH作用之间的相关性。因此，我们提供了体外、体内和计算机模拟证据，有力地表明GH-GHR轴通过驱动MITF调节和ABC转运蛋白介导的药物清除途径，在诱导人类黑色素瘤的化学抗性中发挥作用。
