title: Silencing of argininosuccinate lyase inhibits colorectal cancer formation.
abstract: Arginine and nitric oxide (NO) are important mediators of tumorigenesis in various types of cancer. Dysregulation of NO content by argininosuccinate lyase (ASL) has been previously demonstrated to inhibit the proliferation of liver and breast cancer cells. However, the function of ASL in colon cancer is not well defined. The present study aimed to determine the effect of ASL on colon cancer. Western blot analysis indicated that ASL expression was induced by endoplasmic reticulum stress in HCT116 and SW480 colon cancer cells. Additionally, the expression of ASL in colon cancer tissues was enhanced compared with that in the adjacent normal tissues, and the patients with colon cancer with higher ASL expression exhibited poorer survival rates. Transfection of ASL-targeting short hairpin RNA (shRNA) into HCT116 cells inhibited cell proliferation and decreased anchorage-independent growth in a soft agar assay. In addition, when injected subcutaneously into NOD/SCID mice, stable transfectant ASL-downregulated HCT116 cells exhibited decreased in vivo tumorigenic ability. Flow cytometric analysis of cell cycle progression indicated that ASL-targeting shRNA induced G2/M arrest, and western blot analysis showed that the inhibition of ASL was accompanied by cyclin A2 degradation. Furthermore, ASL-targeting shRNA resulted in increased autophagosomes and decreased NO levels. Inhibition of NO by the NO synthase inhibitor L-NMMA significantly reduced cell proliferation and colony formation. In summary, the results of the present study indicated that ASL-targeting shRNA-induced growth inhibition is associated with decreased cyclin A2 expression and NO content in colon cancer.
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Hau-Lun
authors.initials: HL
authors.lastname: Huang
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Wei-Ching
authors.initials: WC
authors.lastname: Chen
authors.affiliation: Department of Surgery, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Hsu
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Cho
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Hung
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Chih-Yang
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, R.O.C.
authors.forename: Ming-Derg
authors.initials: MD
authors.lastname: Lai
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001120:Arginine / Q000378:metabolism; D001123:Argininosuccinate Lyase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D056751:Cyclin A2 / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D006801:Humans; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009569:Nitric Oxide / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D056751:Cyclin A2; D034741:RNA, Small Interfering; D009569:Nitric Oxide; D001120:Arginine; D001123:Argininosuccinate Lyase