Microvascular Research Laboratories, School of Physiology and Pharmacology, Preclinical Veterinary Sciences Building, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Liverpool, UK.
Br J Cancer. 2014 Jul 29;111(3):477-85. doi: 10.1038/bjc.2014.342. Epub 2014 Jul 10.
Current therapies for metastatic melanoma are targeted either at cancer mutations driving growth (e.g., vemurafenib) or immune-based therapies (e.g., ipilimumab). Tumour progression also requires angiogenesis, which is regulated by VEGF-A, itself alternatively spliced to form two families of isoforms, pro- and anti-angiogenic. Metastatic melanoma is associated with a splicing switch to pro-angiogenic VEGF-A, previously shown to be regulated by SRSF1 phosphorylation by SRPK1. Here, we show a novel approach to preventing angiogenesis-targeting splicing factor kinases that are highly expressed in melanomas.
We used RT-PCR, western blotting and immunohistochemistry to investigate SRPK1, SRSF1 and VEGF expression in tumour cells, and in vivo xenograft assays to investigate SRPK1 knockdown and inhibition in vivo.
In both uveal and cutaneous melanoma cell lines, SRPK1 was highly expressed, and inhibition of SRPK1 by knockdown or with pharmacological inhibitors reduced pro-angiogenic VEGF expression maintaining the production of anti-angiogenic VEGF isoforms. Both pharmacological SRPK1 inhibitors and SRPK1 knockdown reduced growth of human melanomas in vivo, but neither affected cell proliferation in vitro.
These results suggest that selective blocking of pro-angiogenic isoforms by inhibiting splice-site selection with SRPK1 inhibitors reduces melanoma growth. SRPK1 inhibitors may be used as therapeutic agents.
目前针对转移性黑色素瘤的治疗方法要么针对驱动肿瘤生长的癌症突变（例如vemurafenib），要么针对免疫疗法（例如 ipilimumab）。肿瘤的进展还需要血管生成，这是由 VEGF-A 调节的，它本身通过选择性剪接形成两种异构体家族，促血管生成和抗血管生成。转移性黑色素瘤与促血管生成 VEGF-A 的剪接开关有关，以前的研究表明，这是由 SRPK1 磷酸化 SRSF1 调节的。在这里，我们提出了一种针对在黑色素瘤中高度表达的血管生成靶向剪接因子激酶的新方法。
我们使用 RT-PCR、western blot 和免疫组织化学来研究肿瘤细胞中的 SRPK1、SRSF1 和 VEGF 表达，并进行体内异种移植实验来研究 SRPK1 的敲低和体内抑制。
在葡萄膜和皮肤黑色素瘤细胞系中，SRPK1 表达水平较高，通过敲低或用药理学抑制剂抑制 SRPK1 可降低促血管生成的 VEGF 表达，同时维持抗血管生成 VEGF 异构体的产生。两种药理学 SRPK1 抑制剂和 SRPK1 敲低均减少了体内人黑色素瘤的生长，但均不影响体外细胞增殖。
这些结果表明，通过抑制 SRPK1 抑制剂的剪接位点选择来选择性阻断促血管生成异构体可减少黑色素瘤的生长。SRPK1 抑制剂可能被用作治疗剂。
