Decreased cell survival and DNA repair capacity after UVC irradiation in association with down-regulation of GRP78/BiP in human RSa cells

• Published in: Experimental cell research 2005-05, Vol.305 (2), p.244-252
• Main Authors: Zhai, Ling, Kita, Kazuko, Wano, Chieko, Wu, Yuping, Sugaya, Shigeru, Suzuki, Nobuo
• Format: Article
• Language: English
• Subjects: (6–4) Photoproducts; 60 APPLIED LIFE SCIENCES; ANIMAL CELLS; APOPTOSIS; Cell Death - genetics; Cell Death - physiology; Cell Proliferation - radiation effects; Cell Survival - radiation effects; Cells, Cultured; Cisplatin - pharmacology; DIMERS; DNA; DNA - drug effects; DNA - radiation effects; DNA Damage; DNA DAMAGES; DNA Repair - radiation effects; DNA, Antisense - genetics; Down-Regulation; ENDOPLASMIC RETICULUM; EXCISION REPAIR; GRP78/BiP; HEAT-SHOCK PROTEINS; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Heat-Shock Proteins - physiology; Human cells; Humans; IN VITRO; IN VIVO; IRRADIATION; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Molecular Chaperones - physiology; Nucleotide excision repair; NUCLEOTIDES; PLASMIDS; Pyrimidine Dimers - metabolism; SENSITIVITY; THYMINE; Thymine dimers; Ultraviolet Rays; UVC
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2005.01.002

In contrast to extensive studies on the roles of molecular chaperones, such as heat shock proteins, there are only a few reports about the roles of GRP78/BiP, an endoplasmic reticulum (ER) stress-induced molecular chaperone, in mammalian cell responses to DNA-damaging stresses. To investigate whether GRP78/BiP is involved in resistance to a DNA-damaging agent, UVC (principally 254 nm in wavelength), we established human cells with down-regulation of GRP78/BiP by transfection of human RSa cells with antisense cDNA for GRP78/BiP. We found that the transfected cells showed higher sensitivity to UVC-induced cell death than control cells transfected with the vector alone. In the antisense-cDNA transfected cells, the removal capacities of the two major types of UVC-damaged DNA (thymine dimers and (6–4) photoproducts) in vivo and DNA synthesis activity of whole cell extracts to repair UVC-irradiated plasmids in vitro were remarkably decreased compared with those in the control cells. Furthermore, the antisense-cDNA transfected cells also showed slightly higher sensitivity to cisplatin-induced cell death than the control cells. Cisplatin-induced DNA damage is primarily repaired by nucleotide excision repair, like UVC-induced DNA damage. The present results suggest that GRP78/BiP plays a protective role against UVC-induced cell death possibly via nucleotide excision repair, at least in the human RSa cells tested.