title: Silencing glucose-regulated protein 78 induced renal cell carcinoma cell line G1 cell-cycle arrest and resistance to conventional chemotherapy.
abstract: OBJECTIVE
  Glucose-regulated protein 78 (Grp78) is an endoplasmic reticulum chaperone; it maintains endoplasmic reticulum homeostasis and modulates unfolded protein response. The protein is overexpressed in various cancer types, including renal cell carcinoma (RCC). Increased Grp78 expression in patients with RCC is correlated with more aggressive tumors and poorer prognoses. This study investigated the role of Grp78 in regulating tumorigenesis and evaluated the potential of Grp78-targeted therapy for RCC.
  
  
  METHODS
  The expression level of Grp78 was examined in von Hippel-Lindau (VHL)-intact or VHL-null RCC cell lines by reverse transcription polymerase chain reaction and Western blot. Specific Grp78 ribonucleic acid interference was applied as a molecularly Grp78-targeted therapeutic approach. This method enabled us to assess the effects of manipulating Grp78 expression to regulate RCC cell growth.
  
  
  RESULTS
  The Grp78 messenger ribonucleic acid and protein were expressed in both VHL-intact and VHL-null RCC cell lines. The specific inhibition of Grp78 expression suppressed RCC cell growth and colony formation significantly, and induced G1 cell-cycle arrest. We also showed that inhibiting Grp78 expression increased the cells' resistance to the cytotoxicity of the S-phase-specific anticancer drug 5-fluorouracil. This effect was regulated by the unfolded protein response-induced suppression of G1/S transition-related cyclins (D1, E1, and E2) and cyclin-dependent kinase (CDK4 and CDK6) protein expression.
  
  
  CONCLUSIONS
  Overall, our findings indicate the regulatory function of Grp78 in RCC cell proliferation, and provide a molecular-based mechanism of Grp78 positivity in the progression of RCC.
authors: Graduate Institute of Clinical Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Anesthesiology, Taipei Medical University Hospital, Taipei, Taiwan.
authors: Jui-An
authors: JA
authors: Lin
authors: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan.
authors: Sheng-Uei
authors: SU
authors: Fang
authors: Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei, Taiwan.
authors: Chien-Ling
authors: CL
authors: Su
authors: Graduate Institute of Clinical Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan.
authors: Chia-Jung
authors: CJ
authors: Hsiao
authors: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan.
authors: Chun-Chao
authors: CC
authors: Chang
authors: Graduate Institute of Clinical Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan; Division of Nephrology, Department of Internal Medicine, Shuang Ho Hospital, Taipei, Taiwan.
authors: Yuh-Feng
authors: YF
authors: Lin
authors: Graduate Institute of Clinical Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan. Electronic address: ccheng@tmu.edu.tw.
authors: Chao-Wen
authors: CW
authors: Cheng
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D063646:Carcinogenesis; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018450:Disease Progression; D019008:Drug Resistance, Neoplasm; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005472:Fluorouracil / Q000737:chemistry; D016193:G1 Phase; D020868:Gene Silencing; D006360:Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D056811:Unfolded Protein Response
chemical_list: D000970:Antineoplastic Agents; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D034741:RNA, Small Interfering; D005472:Fluorouracil
keywords: Cell cycle; Chemotherapy; Grp78; Herp; UPR; VHL