title: Induction of apoptosis coupled to endoplasmic reticulum stress in human prostate cancer cells by n-butylidenephthalide.
abstract: BACKGROUND
  N-butylidenephthalide (BP) exhibits antitumor effect in a variety of cancer cell lines. The objective of this study was to obtain additional insights into the mechanisms involved in BP induced cell death in human prostate cancer cells.
  
  
  RESULTS
  Two human prostate cancer cell lines, PC-3 and LNCaP, were treated with BP, and subsequently evaluated for their viability and cell cycle profiles. BP caused cell cycle arrest and cell death in both cell lines. The G0/G1 phase arrest was correlated with increase levels of CDK inhibitors (p16, p21 and p27) and decrease of the checkpoint proteins. To determine the mechanisms of BP-induced growth arrest and cell death in prostate cancer cell lines, we performed a microarray study to identify alterations in gene expression induced by BP in the LNCaP cells. Several BP-induced genes, including the GADD153/CHOP, an endoplasmic reticulum stress (ER stress)-regulated gene, were identified. BP-induced ER stress was evidenced by increased expression of the downstream molecules GRP78/BiP, IRE1-α and GADD153/CHOP in both cell lines. Blockage of IRE1-α or GADD153/CHOP expression by siRNA significantly reduced BP-induced cell death in LNCaP cells. Furthermore, blockage of JNK1/2 signaling by JNK siRNA resulted in decreased expression of IRE1-α and GADD153/CHOP genes, implicating that BP-induced ER stress may be elicited via JNK1/2 signaling in prostate cancer cells. BP also suppressed LNCaP xenograft tumor growth in NOD-SCID mice. It caused 68% reduction in tumor volume after 18 days of treatment.
  
  
  CONCLUSIONS
  Our results suggest that BP can cause G0/G1 phase arrest in prostate cancer cells and its cytotoxicity is mediated by ER stress induction. Thus, BP may serve as an anticancer agent by inducing ER stress in prostate cancer.
authors.affiliation: Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan.
authors.forename: Sheng-Chun
authors.initials: SC
authors.lastname: Chiu
authors.forename: Shee-Ping
authors.initials: SP
authors.lastname: Chen
authors.forename: Sung-Ying
authors.initials: SY
authors.lastname: Huang
authors.forename: Mei-Jen
authors.initials: MJ
authors.lastname: Wang
authors.forename: Shinn-Zong
authors.initials: SZ
authors.lastname: Lin
authors.forename: Horng-Jyh
authors.initials: HJ
authors.lastname: Harn
authors.forename: Cheng-Yoong
authors.initials: CY
authors.lastname: Pang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D004722:Endoribonucleases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D059585:G1 Phase Cell Cycle Checkpoints; D006801:Humans; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048056:Mitogen-Activated Protein Kinase 9 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010796:Phthalic Anhydrides / Q000494:pharmacology*; D011471:Prostatic Neoplasms; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D051742:Transcription Factor CHOP / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; C497249:DDIT3 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; D010796:Phthalic Anhydrides; D034741:RNA, Small Interfering; D051742:Transcription Factor CHOP; D050760:Cyclin-Dependent Kinase Inhibitor p27; D048056:Mitogen-Activated Protein Kinase 9; C528229:ERN1 protein, human; D017346:Protein Serine-Threonine Kinases; D048055:Mitogen-Activated Protein Kinase 8; D004722:Endoribonucleases; C026105:butylidenephthalide