title: [Keratin 18 phosphorylation increases autophagy of colorectal cancer HCT116 cells and enhanced its sensitivity to oxaliplatin].
abstract: OBJECTIVE
  To study the correlation between the phosphorylation of keratin 18 (K18) and the autophagy and apoptosis of HCT116 cells under the effect of oxaliplatin (OXA) and investigate its possible mechanism.
  
  
  METHODS
  HCT116 cells were transfected with empty plasmid, wild-type K18 expression plasmid and 33, 52 phosphorylation site mutated K18 (Ser33/52A) expression plasmid separately, and all cells were then treated with 60 μmol/L OXA, followed by supplementation of autophagy inhibitor 3-methyladenine (3-MA) or autophagy inducer rapamycin. FITC-conjugated annexin V and propidium iodide (PI) double staining combined with flow cytometry, calcein-AM/PI staining were used to analyze the effects of K18 and its mutants on cell apoptosis; Western blotting was performed to detect the expressions of K18 phosphorylation, autophagy related proteins microtubule associated protein 1 light chain 3 (LC3) and beclin-1.
  
  
  RESULTS
  Transfection of Ser33/52A plasmid significantly reduced the level of K18 phosphorylation. After treated with OXA, the apoptosis rate of K18 plasmid transfected group was significantly higher than that of empty plasmid transfected group, while the apoptosis rate of Ser33/52A plasmid transfected HCT116 cells was significantly lower than that of empty plasmid or K18 plasmid transfected group. Compared with empty plasmid group, the autophagy of K18 plasmid transfected group was significantly promoted, while the autophagy in Ser33/52A plasmid transfected group was significantly inhibited.
  
  
  CONCLUSIONS
  K18 overexpression enhanced the autophagy in HCT116 cells and increased its sensitivity to OXA. The decrease of K18 ser33 and ser52 phosphorylation inhibited autophagy and decreased apoptosis of HCT116 cells.
authors.affiliation: Department of General Surgery, Shandong Cancer Hospital, Jinan 250117; School of Medicine and Life Sciences, Shandong Academy of Medical Sciences, University of Jinan, Jinan 250022, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yan
authors.affiliation: Department of Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China.
authors.forename: Buxin
authors.initials: B
authors.lastname: Kou
authors.affiliation: Department of General Surgery, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Department of General Surgery, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Chai
authors.affiliation: Department of Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China.
authors.forename: Dexi
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of General Surgery, Shandong Cancer Hospital, Jinan 250117, China. *Corresponding author, E-mail: hliangbb@163.com.
authors.forename: Hongliang
authors.initials: H
authors.lastname: Guo
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D045325:HCT116 Cells; D006801:Humans; D053538:Keratin-18 / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009154:Mutation; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D000077150:Oxaliplatin; D010766:Phosphorylation; D012694:Serine / Q000235:genetics / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; D053538:Keratin-18; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D012694:Serine; C025946:3-methyladenine; D000225:Adenine; D020123:Sirolimus