title: Expression and function of classical protein kinase C isoenzymes in gastric cancer cell line and its drug-resistant sublines.
abstract: OBJECTIVE
  To investigate the expression and function of classical protein kinase C (PKC) isoenzymes in inducing MDR phenotype in gastric cancer cells.
  
  
  METHODS
  Two cell lines were used in the study: gastric cancer cell SGC7901 and its drug-resistant cell SGC7901/VCR stepwise-selected by vincristine 0.3, 0.7 and 1.0 mg.L(-1), respectively. The expression of classical PKC (cPKC) isoenzymes in SGC7901 cells and SGC7901/VCR cells were detected using immunofluorescent cytochemistry, laser confocal scanning microscope and Western blot. The effects of anti-PKC isoenzymes antibody on adriamycin accumulation in SGC7901/VCR cells were determined using flow cytometric analysis.
  
  
  RESULTS
  (1)SGC7901 cells exhibited positive staining of PKC-alpha. SGC7901/VCR cells exhibited stronger staining of PKC-alpha than SGC7901 cells. The higher dosage vincristine selected, the much stronger staining of PKC-alpha was observed on SGC7901/VCR cells. (2)Both SGC7901 and SGC7901/VCR cells exhibited positive staining of PKC-beta I and PKC-beta II with no significant difference. (3) Compared with SGC7901, SGC7901/VCR cells had decreased adriamycin accumulation and retention. Accumulation of adriamycin in SGC7901 was 5.21+/-2.56 mg.L(-1),in SGC7901/VCR 0.3 was 0.85+/-0.29 mg.L(-1), in SGC7901/VCR 0.7 was 0.81+/-0.32 mg.L(-1), and in SGC7901/VCR 1.0 was 0.80+/-0.33 mg.L(-1); Retention of adriamycin in SGC 7901 was 2.51+/-1.23 mg.L(-1), in SGC7901/VCR 0.3 was 0.47+/-0.14 mg.L(-1), in SGC7901/VCR 0.7 was 0.44+/-0.15 mg.L(-1), and in SGC 7901/VCR 1.0 was 0.41+/-0.11 mg.L(-1). (4) Fluorescence intensity presented adriamycin accumulation in SGC7901/VCR cells was increased from 1.14+/-0.36 to 2.71+/-0.94 when cells were co-incubated with anti-PKC-alpha but not with anti-PKC-beta I PKC-beta II and PKCgamma antibodies.
  
  
  CONCLUSIONS
  PKC-alpha, but not PKC-beta I, PKC-beta II or PKCgamma, may play a role in multidrug resistance of gastric cancer cells SGC7901/VCR.
authors.affiliation: Institute of Digestive Disease, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, Shaanxi Province, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Han
authors.forename: Zhe-Yi
authors.initials: ZY
authors.lastname: Han
authors.forename: Xin-Min
authors.initials: XM
authors.lastname: Zhou
authors.forename: Ru
authors.initials: R
authors.lastname: Shi
authors.forename: Yue
authors.initials: Y
authors.lastname: Zheng
authors.forename: Yong-Quan
authors.initials: YQ
authors.lastname: Shi
authors.forename: Ji-Yan
authors.initials: JY
authors.lastname: Miao
authors.forename: Bo-Rong
authors.initials: BR
authors.lastname: Pan
authors.forename: Dai-Ming
authors.initials: DM
authors.lastname: Fan
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000494:pharmacology
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D007527:Isoenzymes; D014750:Vincristine; D011493:Protein Kinase C