title: Down-regulation of E-cadherin enhances prostate cancer chemoresistance via Notch signaling.
abstract: BACKGROUND
  The chemoresistance of prostate cancer (PCa) is invariably associated with the aggressiveness and metastasis of this disease. New emerging evidence indicates that the epithelial-to-mesenchymal transition (EMT) may play pivotal roles in the development of chemoresistance and metastasis. As a hallmark of EMT, E-cadherin is suggested to be a key marker in the development of chemoresistance. However, the molecular mechanisms underlying PCa chemoresistance remain unclear. The current study aimed to explore the association between EMT and chemoresistance in PCa as well as whether changing the expression of E-cadherin would affect PCa chemoresistance.
  
  
  METHODS
  Parental PC3 and DU145 cells and their chemoresistant PC3-TxR and DU145-TxR cells were analyzed. PC3-TxR and DU145-TxR cells were transfected with E-cadherin-expressing lentivirus to overexpress E-cadherin; PC3 and DU145 cells were transfected with small interfering RNA to silence E-cadherin. Changes of EMT phenotype-related markers and signaling pathways were assessed by Western blotting and quantitative real-time polymerase chain reaction. Tumor cell migration, invasion, and colony formation were then evaluated by wound healing, transwell, and colony formation assays, respectively. The drug sensitivity was evaluated using MTS assay.
  
  
  RESULTS
  Chemoresistant PC3-TxR and DU145-TxR cells exhibited an invasive and metastatic phenotype that associated with EMT, including the down-regulation of E-cadherin and up-regulation of Vimentin, Snail, and N-cadherin, comparing with that of parental PC3 and DU145 cells. When E-cadherin was overexpressed in PC3-TxR and DU145-TxR cells, the expression of Vimentin and Claudin-1 was down-regulated, and tumor cell migration and invasion were inhibited. In particular, the sensitivity to paclitaxel was reactivated in E-cadherin-overexpressing PC3-TxR and DU145-TxR cells. When E-cadherin expression was silenced in parental PC3 and DU145 cells, the expression of Vimentin and Snail was up-regulated, and, particularly, the sensitivity to paclitaxel was decreased. Interestingly, Notch-1 expression was up-regulated in PC3-TxR and DU145-TxR cells, whereas the E-cadherin expression was down-regulated in these cells comparing with their parental cells. The use of γ-secretase inhibitor, a Notch signaling pathway inhibitor, significantly increased the sensitivity of chemoresistant cells to paclitaxel.
  
  
  CONCLUSIONS
  The down-regulation of E-cadherin enhances PCa chemoresistance via Notch signaling, and inhibiting the Notch signaling pathway may reverse PCa chemoresistance.
authors.affiliation: Center for Translational Medicine, Guangxi Medical University, 12th Floor, Medical Science Research Building, No. 22 Shuangyong Road, Nanning, Guangxi, 530021, P. R. China.|Key Laboratory of Longevity and Ageing-related Diseases, Ministry of Education, Nanning, Guangxi, 530021, P. R. China.|Department of Urology and Pathology, School of Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: Wenchu
authors.initials: W
authors.lastname: Wang
authors.affiliation: Center for Translational Medicine, Guangxi Medical University, 12th Floor, Medical Science Research Building, No. 22 Shuangyong Road, Nanning, Guangxi, 530021, P. R. China.|Key Laboratory of Longevity and Ageing-related Diseases, Ministry of Education, Nanning, Guangxi, 530021, P. R. China.
authors.forename: Lihui
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Urology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, 920-1192, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mizokami
authors.affiliation: Center for Translational Medicine, Guangxi Medical University, 12th Floor, Medical Science Research Building, No. 22 Shuangyong Road, Nanning, Guangxi, 530021, P. R. China.|Key Laboratory of Longevity and Ageing-related Diseases, Ministry of Education, Nanning, Guangxi, 530021, P. R. China.
authors.forename: Junlin
authors.initials: J
authors.lastname: Shi
authors.affiliation: Center for Translational Medicine, Guangxi Medical University, 12th Floor, Medical Science Research Building, No. 22 Shuangyong Road, Nanning, Guangxi, 530021, P. R. China.|Key Laboratory of Longevity and Ageing-related Diseases, Ministry of Education, Nanning, Guangxi, 530021, P. R. China.
authors.forename: Chunlin
authors.initials: C
authors.lastname: Zou
authors.affiliation: Department of Urology and Pathology, School of Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: Jinlu
authors.initials: J
authors.lastname: Dai
authors.affiliation: Department of Urology and Pathology, School of Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: Evan T
authors.initials: ET
authors.lastname: Keller
authors.affiliation: Center for Translational Medicine, Guangxi Medical University, 12th Floor, Medical Science Research Building, No. 22 Shuangyong Road, Nanning, Guangxi, 530021, P. R. China. luyi5555@hotmail.com.|Key Laboratory of Longevity and Ageing-related Diseases, Ministry of Education, Nanning, Guangxi, 530021, P. R. China. luyi5555@hotmail.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Center for Translational Medicine, Guangxi Medical University, 12th Floor, Medical Science Research Building, No. 22 Shuangyong Road, Nanning, Guangxi, 530021, P. R. China. jianzhang008@hotmail.com.|Key Laboratory of Longevity and Ageing-related Diseases, Ministry of Education, Nanning, Guangxi, 530021, P. R. China. jianzhang008@hotmail.com.|Department of Biology and School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, P. R. China. jianzhang008@hotmail.com.|Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15232, USA. jianzhang008@hotmail.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000818:Animals; D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D051379:Mice; D017239:Paclitaxel / Q000008:administration & dosage* / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction; D023041:Xenograft Model Antitumor Assays
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D051880:Receptors, Notch; D017239:Paclitaxel
keywords: Chemoresistance; E-cadherin; Epithelial-to-mesenchymal transition; Notch signaling; Prostate cancer