title: TM4SF1 Promotes Gemcitabine Resistance of Pancreatic Cancer In Vitro and In Vivo.
abstract: BACKGROUND
  TM4SF1 is overexpressed in pancreatic ductal adenocarcinoma (PDAC) and affects the development of this cancer. Also, multidrug resistance (MDR) is generally associated with tumor chemoresistance in pancreatic cancer. However, the correlation between TM4SF1 and MDR remains unknown. This research aims to investigate the effect of TM4SF1 on gemcitabine resistance in PDAC and explore the possible molecular mechanism between TM4SF1 and MDR.
  
  
  METHODS
  The expression of TM4SF1 was evaluated in pancreatic cancer cell lines and human pancreatic duct epithelial (HPDE) cell lines by quantitative RT-PCR. TM4SF1 siRNA transfection was carried out using Hiperfect transfection reagent to knock down TM4SF1. The transcripts were analyzed by quantitative RT-PCR, RT-PCR and western blotting for further study. The cell proliferation and apoptosis were obtained to investigate the sensitivity to gemcitabine of pancreatic cancer cells after silencing TM4SF1 in vitro. We demonstrated that cell signaling of TM4SF1 mediated chemoresistance in cancer cells by assessing the expression of multidrug resistance (MDR) genes using quantitative RT-PCR. In vivo, we used orthotopic pancreatic tumor models to investigate the effect of proliferation after silencing TM4SF1 by a lentivirus-mediated shRNA in MIA PaCa-2 cell lines.
  
  
  RESULTS
  The mRNA expression of TM4SF1 was higher in seven pancreatic cancer cell lines than in HPDE cell lines. In three gemcitabine-sensitive cell lines (L3.6pl, BxPC-3, SU86.86), the expression of TM4SF1 was lower than that in four gemcitabine-resistant cell lines (MIA PaCa-2, PANC-1, Hs766T, AsPC-1). We evaluated that TM4SF1 was a putative target for gemcitabine resistance in pancreatic cancer cells. Using AsPC-1, MIA PaCa-2 and PANC-1, we investigated that TM4SF1 silencing affected cell proliferation and increased the percentages of cell apoptosis mediated by treatment with gemcitabine compared with cells which were treated with negative control. This resistance was associated with the expression of multidrug resistance genes including ABCB1 and ABCC1. In vivo, silencing of TM4SF1 in MIA PaCa-2 cell lines increased the effectiveness of gemcitabine-based treatment in orthotopic pancreatic tumor models evaluated using noninvasive bioluminescent imaging.
  
  
  CONCLUSIONS
  These findings suggest that TM4SF1 is a surface membrane antigen that is highly expressed in pancreatic cancer cells and increases the chemoresistance to gemcitabine. Thus, TM4SF1 may be a promising target to overcome the chemoresistance of pancreatic cancer.
authors.affiliation: Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200092, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Cao
authors.affiliation: Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200092, China.
authors.forename: Jiachun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, 77030, United States of America.
authors.forename: Vijaya
authors.initials: V
authors.lastname: Ramachandran
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, 77030, United States of America.
authors.forename: Thiruvengadam
authors.initials: T
authors.lastname: Arumugam
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, 77030, United States of America.
authors.forename: Defeng
authors.initials: D
authors.lastname: Deng
authors.affiliation: Department of Gastroenterology, Changhai Hospital, the Second Military Medical University, Shanghai, 200433, China.
authors.forename: Zhaoshen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200092, China.
authors.forename: Leiming
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, 77030, United States of America.
authors.forename: Craig D
authors.initials: CD
authors.lastname: Logsdon
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000096:biosynthesis; D000818:Animals; D000954:Antigens, Surface / Q000235:genetics*; D017209:Apoptosis / Q000187:drug effects; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis; D009363:Neoplasm Proteins / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D000093542:Gemcitabine
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D000954:Antigens, Surface; D003841:Deoxycytidine; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000093542:Gemcitabine; C513055:ABCB1 protein, human; C074075:TM4SF1 protein, human; C421109:multidrug resistance-associated protein 1