Inhibition of UCH-L1 Deubiquitinating Activity with Two Forms of LDN-57444 Has Anti-Invasive Effects in Metastatic Carcinoma Cells

• DOI: 10.3390/ijms20153733
• Publication Date: 2019-07-31T15:37:07Z
• Authors: Eiji Kobayashi; Duhyeong Hwang; Anjali Bheda-Malge; Christopher B. Wh...; Alexander V. Kabanov; Satoru Kondo; Mitsuharu Aga; Tomokazu Yoshizaki; Joseph S. Pagano; Marina Sokolsky; Julia Shakelford
• Keywords: 0301 basic medicine; Herpesvirus 4, Human; Indoles; Cell Survival; Antineoplastic Agents; Exosomes; Article; 03 medical and health sciences; Cell Movement; Cell Line, Tumor; Nasopharynx; Oximes; Cell Adhesion; Humans; markers of invasion and metastasis; Oxazoles; Micelles; Cell Proliferation; Drug Carriers; Mouth; poly (2-oxazoline) micelle; Epithelial Cells; nanoformulation; 3. Good health; de-ubiquitination; Gene Expression Regulation, Neoplastic; Nanoparticles; Ubiquitin Thiolesterase

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.