Lineberger Comprehensive Cancer Center, UNC at Chapel Hill, Department of Immunology and Microbiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Division of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kanazawa University, Kanazawa 920-8640, Japan.
Int J Mol Sci. 2019 Jul 31;20(15):3733. doi: 10.3390/ijms20153733.
Normally ubiquitin C-terminal hydrolase L1 (UCH-L1) is expressed in the central nervous and reproductive systems of adults, but its de novo expression has been detected in many human cancers. There is a growing body of evidence that UCH-L1 de-ubiquitinating (DUB) activity plays a major pro-metastatic role in certain carcinomas. Here we tested anti-metastatic effects of the small-molecule inhibitor of UCH-L1 DUB activity, LDN-57444, in cell lines from advanced oral squamous cell carcinoma (OSCC) as well as invasive nasopharyngeal (NP) cell lines expressing the major pro-metastatic gene product of Epstein-Barr virus (EBV) tumor virus, LMP1. To overcome the limited aqueous solubility of LDN-57444 we developed a nanoparticle formulation of LDN-57444 by incorporation of the compound in polyoxazoline micellear nanoparticles (LDN-POx). LDN-POx nanoparticles were equal in effects as the native compound in vitro. Our results demonstrate that inhibition of UCH-L1 DUB activity with LDN or LDN-POx inhibits secretion of exosomes and reduces levels of the pro-metastatic factor in exosomal fractions. Both forms of UCH-L1 DUB inhibitor suppress motility of metastatic squamous carcinoma cells as well as nasopharyngeal cells expressing EBV pro-metastatic Latent membrane protein 1 (LMP1) in physiological assays. Moreover, treatment with LDN and LDN-POx resulted in reduced levels of pro-metastatic markers, a decrease of carcinoma cell adhesion, as well as inhibition of extra-cellular vesicle (ECV)-mediated transfer of viral invasive factor LMP1. We suggest that soluble inhibitors of UCH-L1 such as LDN-POx offer potential forms of treatment for invasive carcinomas including EBV-positive malignancies.
通常情况下，泛素 C 端水解酶 L1（UCH-L1）仅在成人的中枢神经系统和生殖系统中表达，但在许多人类癌症中已检测到其新生表达。越来越多的证据表明，UCH-L1 去泛素化（DUB）活性在某些癌中发挥主要的促转移作用。在这里，我们测试了小分子 UCH-L1 DUB 活性抑制剂 LDN-57444 在晚期口腔鳞状细胞癌（OSCC）细胞系以及表达 EBV 肿瘤病毒主要促转移基因产物 LMP1 的侵袭性鼻咽（NP）细胞系中的抗转移作用。为了克服 LDN-57444 的有限水溶性，我们通过将该化合物整合到聚恶唑啉胶束纳米粒子（LDN-POx）中来开发 LDN-57444 的纳米颗粒制剂。LDN-POx 纳米颗粒在体外与天然化合物具有同等效果。我们的结果表明，用 LDN 或 LDN-POx 抑制 UCH-L1 DUB 活性可抑制外泌体的分泌并降低外泌体部分中促转移因子的水平。两种形式的 UCH-L1 DUB 抑制剂均可抑制转移性鳞状癌细胞以及表达 EBV 促转移潜伏膜蛋白 1（LMP1）的鼻咽细胞的运动。此外，用 LDN 和 LDN-POx 处理会导致促转移标志物水平降低、癌细胞黏附减少以及细胞外囊泡（ECV）介导的病毒侵袭因子 LMP1 的转移受到抑制。我们认为，UCH-L1 的可溶性抑制剂（如 LDN-POx）为包括 EBV 阳性恶性肿瘤在内的侵袭性癌提供了潜在的治疗形式。
