title: Attenuation of argininosuccinate lyase inhibits cancer growth via cyclin A2 and nitric oxide.
abstract: Arginine biosynthesis and nitric oxide (NO) production are important for cancer homeostasis. Degradation of arginine may be used to inhibit liver tumors with low argininosuccinate synthetase (ASS) expression. In this report, we investigated an alternative therapeutic approach by targeting argininosuccinate lyase (ASL). ASL is transcriptionally induced by endoplasmic reticulum stress and is overexpressed in some human liver tumors. Knockdown of ASL expression by short hairpin RNA (shRNA) in three liver cancer cell lines, ML-1, HuH-7, and HepG2, decreased colony formation in vitro and tumor growth in vivo. Furthermore, lentiviral infection of ASL shRNA inhibited tumor growth in a therapeutic animal tumor model. Analysis of ASL shRNA on the cell-cycle progression revealed a G2-M delay. Among cell-cycle regulatory molecules, cyclin A2 expression was reduced. Reintroduction of exogenous cyclin A2 restored the cell growth in ASL-knockdown cells. Autophagy was observed in the cells treated with ASL shRNA, as shown by an increase in LC3-II levels and autophagosome formation. The total cellular arginine level was not altered significantly. Inhibition of autophagy further attenuated cell growth, suggesting that autophagy induced by ASL shRNA plays a feedback prosurvival function. Knockdown of ASL reduced NO content, and addition of NO donor partially recovered the growth inhibition by ASL shRNA. In summary, downregulation of ASL attenuated tumor growth and the inhibition was mainly mediated by a decrease of cyclin A2 and NO.
authors: Corresponding Author: Ming-Derg Lai, Center for Infectious Diseases and Signaling Research, College of Medicine, National Cheng Kung University, University Road, No. 1, Tainan 701, Taiwan. a1211207@mail.ncku.edu.tw.
authors: Hau-Lun
authors: HL
authors: Huang
authors: Hui-Ping
authors: HP
authors: Hsu
authors: Shu-Chu
authors: SC
authors: Shieh
authors: Yung-Sheng
authors: YS
authors: Chang
authors: Wei-Ching
authors: WC
authors: Chen
authors: Chien-Yu
authors: CY
authors: Cho
authors: Chiao-Fang
authors: CF
authors: Teng
authors: Ih-Jen
authors: IJ
authors: Su
authors: Wen-Chun
authors: WC
authors: Hung
authors: Ming-Derg
authors: MD
authors: Lai
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism; D001123:Argininosuccinate Lyase / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D056751:Cyclin A2 / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D008114:Liver Neoplasms, Experimental; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009569:Nitric Oxide / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology*
chemical_list: D056751:Cyclin A2; D034741:RNA, Small Interfering; D009569:Nitric Oxide; D001120:Arginine; D001123:Argininosuccinate Lyase