title: Downregulation of uridine-cytidine kinase like-1 decreases proliferation and enhances tumor susceptibility to lysis by apoptotic agents and natural killer cells.
abstract: Natural killer (NK) cells target and kill tumor cells by direct anti-tumor cytotoxicity. NK lytic-associated molecule (NKLAM) is a protein involved in this cytolytic function. Acting as an E3 ubiquitin ligase, NKLAM binds to and ubiquitinates a novel protein, uridine-cytidine kinase like-1 (UCKL-1), targeting it for degradation. However, UCKL-1's function in tumor cell survival and NK cell cytotoxicity is unknown. UCKL-1's homology to uridine kinases and over expression in tumor cells suggests a role for UCKL-1 in tumor growth and/or survival. We propose that NKLAM and UCKL-1 interact in the tumor cell, where degradation of UCKL-1 leads to increased tumor cell apoptosis. Here we use RNA interference to downregulate UCKL-1 expression in K562 erythroleukemia cells. It was seen that downregulation of UCKL-1 initiated apoptosis and slowed the cell cycle, resulting in lower growth in the small interfering UCKL-1 RNA treated K562 cell culture. In addition, the chemotherapeutic agent staurosporine was seen to be more effective in inducing cell death by apoptosis in UCKL-1 depleted K562 cells compared with controls. We also found that UCKL-1 depleted K562 cells were more susceptible to NK mediated cytolysis than controls. These results indicate a role for UCKL-1 in tumor cell survival and suggest possible therapeutic potential of UCKL-1 inhibitors in cancer treatment.
authors: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA. ecoffey1@slu.edu
authors: Elise C
authors: EC
authors: Ambrose
authors: Jacki
authors: J
authors: Kornbluth
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D005047:Etoposide / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D009369:Neoplasms / Q000201:enzymology* / Q000276:immunology / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D014541:Uridine Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D005047:Etoposide; C546408:UCKL1 protein, human; D014541:Uridine Kinase; D053148:Caspase 3; D053179:Caspase 7; D019311:Staurosporine