title: Programmed cell death 4 (PDCD4) mediates the sensitivity of gastric cancer cells to TRAIL-induced apoptosis by down-regulation of FLIP expression.
abstract: Tumor necrosis factor-related apoptosis induced ligand (TRAIL) is an important apoptosis inducer in a variety of tumor cells. In the present study, we determined the underlying molecular mechanisms by which certain gastric cancer cells are resistant to TRAIL. We first detected expression of programmed cell death 4 (PDCD4) in three gastric cancer cell lines and identified its association with the sensitivity of gastric cancer cells to TRAIL. We then stably transfected PDCD4 cDNA or shRNA into these gastric cell lines. Our data showed that restoration of PDCD4 expression induced TRAIL sensitivity, whereas knockdown of PDCD4 expression reduced the sensitivity of these tumor cells to TRAIL treatment. PDCD4 was able to suppress expression of FLICE-inhibiting protein (FLIP), a negative regulator of apoptosis. Knockdown of FLIP expression using FLIP shRNA had similar effects as those of restored PDCD4 expression. Furthermore, the proteasome inhibitor MG132 was able to inhibit expression of FLIP mRNA and protein and upregulate the sensitivity of these cells to TRAIL treatment. Taken together, the results from the current study demonstrated that PDCD4 plays an important role in mediating the sensitivity of gastric cancer cells to TRAIL-induced apoptosis through FLIP suppression. Therefore, the proteasome inhibitor MG132 should be further evaluated for combination therapy with TRAIL.
authors.affiliation: Department of Gastroenterology, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Wang
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhao
authors.forename: Hongbin
authors.initials: H
authors.lastname: Wang
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Sun
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Peng
authors.forename: Gang
authors.initials: G
authors.lastname: Zhou
authors.forename: Lilin
authors.initials: L
authors.lastname: Fan
authors.forename: Xingwei
authors.initials: X
authors.lastname: Wang
authors.forename: Shiming
authors.initials: S
authors.lastname: Yang
authors.forename: Rongquan
authors.initials: R
authors.lastname: Wang
authors.forename: Dianchun
authors.initials: D
authors.lastname: Fang
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics* / Q000378:metabolism; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D034741:RNA, Small Interfering / Q000494:pharmacology; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C114487:PDCD4 protein, human; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand