Alshaker Heba, Wang Qi, Brewer Daniel, Pchejetski Dmitri
School of Medicine, University of East Anglia, Norwich, United Kingdom.
Department of Pharmacology and Biomedical Sciences, Faculty of Pharmacy and Medical Sciences, University of Petra, Amman, Jordan.
Front Pharmacol. 2019 Mar 27;10:303. doi: 10.3389/fphar.2019.00303. eCollection 2019.
Sphingosine kinases 1 and 2 (SK1 and SK2) are proto-oncogenic isozymes expressed in many human tumors and associated with chemoresistance and poor prognosis. They are well-recognized therapy targets and their inhibition was shown to induce tumor volume reduction and chemosensitization in multiple cancer models. Oncogenic signaling is extremely complex and often cross-regulated. Designing molecular therapies and their combinations requires rational approaches to avoid redundant targeting or developing resistance. In this study, we have performed RNA transcriptome microarray analysis of two breast and two prostate metastatic cancer cell lines treated with siRNAs targeting SK1 or SK2. In prostate cancer cell lines SK1 knockdown (KD) has significantly changed expression of several genes including downregulation of and upregulation of ETS1. SK2 KD also affected expression of multiple genes including downregulation of and and upregulation of , and . Similarly, in breast cancer cells SK1 KD led to downregulation of , and and upregulation of , and . SK2 KD in breast cancer cells has decreased expression of and and increased expression of and . Gene-set enrichment analysis of known biochemical pathways showed that in prostate and breast cell lines SKs KD have altered multiple pathways. SK1 KD altered chromatin assembly, regulation of G1/S transition and mitosis, Wnt and MAP kinase signaling and cell motility. SK2 KD altered RAS protein signal transduction, regulation of MAP kinase and serine/threonine kinase activity, cell motility, small GTPase mediated signal transduction and phosphatidylinositol 3-kinase (PI3K) signaling. Through genome-wide microarray analysis, we have identified important molecular pathways affected by SK1 and SK2 KD. It appears that while KD of both genes leads to a decrease in individual pro-tumorigenic genes, there is a universal cellular response resulting in upregulation of several known pro-survival and pro-tumorigenic pathways such as MAPK, RAS, and PI3K, which may mediate cancer resistance to anti-SKs therapies. Our data point out to the potential advantage of certain molecular therapy combinations in targeting prostate and breast cancer. Further signaling studies are required to confirm the individual involvement of identified pathways.
鞘氨醇激酶1和2（SK1和SK2）是原癌基因同工酶，在许多人类肿瘤中表达，并与化疗耐药性和不良预后相关。它们是公认的治疗靶点，在多种癌症模型中，抑制它们可使肿瘤体积缩小并产生化疗增敏作用。致癌信号极其复杂，且常常相互交叉调节。设计分子疗法及其组合需要合理的方法，以避免重复靶向或产生耐药性。在本研究中，我们对用靶向SK1或SK2的小干扰RNA（siRNA）处理的两种乳腺癌和两种前列腺癌转移细胞系进行了RNA转录组微阵列分析。在前列腺癌细胞系中，SK1基因敲低（KD）显著改变了几个基因的表达，包括[未提及基因名称1]的下调和ETS1的上调。SK2基因敲低也影响了多个基因的表达，包括[未提及基因名称2]和[未提及基因名称3]的下调以及[未提及基因名称4]和[未提及基因名称5]的上调。同样，在乳腺癌细胞中，SK1基因敲低导致[未提及基因名称6]、[未提及基因名称7]和[未提及基因名称8]的下调以及[未提及基因名称9]和[未提及基因名称10]的上调。乳腺癌细胞中的SK2基因敲低使[未提及基因名称11]和[未提及基因名称12]的表达降低，[未提及基因名称13]和[未提及基因名称14]的表达增加。对已知生化途径的基因集富集分析表明，在前列腺和乳腺癌细胞系中，SK基因敲低改变了多个途径。SK1基因敲低改变了染色质组装、G1/S期转换和有丝分裂的调控、Wnt和丝裂原活化蛋白激酶（MAP激酶）信号传导以及细胞运动性。SK2基因敲低改变了RAS蛋白信号转导、MAP激酶和丝氨酸/苏氨酸激酶活性的调控、细胞运动性、小GTP酶介导的信号转导以及磷脂酰肌醇3激酶（PI3K）信号传导。通过全基因组微阵列分析，我们确定了受SK1和SK2基因敲低影响的重要分子途径。似乎虽然两个基因的敲低都导致单个促肿瘤基因的减少，但存在一种普遍的细胞反应，导致几个已知的促生存和促肿瘤途径如MAPK、RAS和PI3K上调，这可能介导癌症对抗SK疗法的耐药性。我们的数据指出了某些分子疗法组合在靶向前列腺癌和乳腺癌方面的潜在优势。需要进一步的信号传导研究来证实所确定途径的具体作用。
