Down-regulation of BiP/GRP78 sensitizes resistant prostate cancer cells to gene-therapeutic overexpression of REIC/Dkk-3.
We have recently shown that an adenovirus carrying REIC/Dkk-3 (Ad-REIC) exhibits a potent tumor-specific cell-killing function for various human cancers. It has also become evident that some human cancers are resistant to Ad-REIC-induced apoptosis. The aim of the present study was to determine the molecular mechanisms of resistance to Ad-REIC. First, we isolated resistant clones from a human prostate cancer cell line, PC3, after repeated exposure to Ad-REIC. Infection efficiency of the adenovirus vector and expression level of REIC/Dkk-3 in the resistant clones were similar to those in the parental PC3 cells. By screening for alteration in levels and functional status of proteins involved in Ad-REIC-induced apoptosis, we found that BiP/GRP78, an ER-residing chaperone protein, was expressed at higher levels consistently among resistant cells. Expression levels of BiP and rates of apoptosis induced by Ad-REIC were inversely correlated. Down-regulation of BiP with siRNA sensitized the resistant cells to Ad-REIC in vivo as well as in culture. These results indicate that BiP is a major determinant of resistance to Ad-REIC-induced apoptosis. Thus BiP is useful for diagnosis of inherent and acquired resistance of cancers and also as a target molecule to overcome resistance to the gene therapeutic Ad-REIC.
Tanimoto
Ryuta
R
Department of Cell Biology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
Sakaguchi
Masakiyo
M
Abarzua
Fernando
F
Kataoka
Ken
K
Kurose
Kaoru
K
Murata
Hitoshi
H
Nasu
Yasutomo
Y
Kumon
Hiromi
H
Huh
Nam-Ho
NH
D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics; D018925:Chemokines; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D000091342:Endoplasmic Reticulum Chaperone BiP; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D015316:Genetic Therapy; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D015398:Signal Transduction; D023041:Xenograft Model Antitumor Assays
D048868:Adaptor Proteins, Signal Transducing; D018925:Chemokines; C498624:DKK3 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins