title: Angiotensin II type 2 receptor signaling significantly attenuates growth of murine pancreatic carcinoma grafts in syngeneic mice.
abstract: BACKGROUND
  Pancreatic cancer is one of the most aggressive human malignancies, with a very poor prognosis. To evaluate the effect of angiotensin II (Ang II) type 2 receptor (AT2) expression in the host's body on the growth of pancreatic carcinoma, we have investigated the growth of mouse pancreatic ductal carcinoma grafts in syngeneic wild type and AT2 receptor-deficient (AT2-KO) mice.
  
  
  METHODS
  The role of AT2 receptor-signaling in stromal cells on the growth of murine pancreatic carcinoma cells (PAN02) was studied using various in vitro and in vivo assays. In vivo cell proliferation, apoptosis, and vasculature in tumors were monitored by Ki-67 immunostaining, TUNEL assay, and von Willebrand factor immunostaining, respectively. In the co-culture study, cell proliferation was measured by MTT cell viability assay. All the data were analyzed using t-test and data were treated as significant when p < 0.05.
  
  
  RESULTS
  Our results show that the growth of subcutaneously transplanted syngeneic xenografts of PAN02 cells, mouse pancreatic ductal carcinoma cells derived from the C57/BL6 strain, was significantly faster in AT2-KO mice compared to control wild type mice. Immunohistochemical analysis of tumor tissue revealed significantly more Ki-67 positive cells in xenografts grown in AT2-KO mice than in wild type mice. The index of apoptosis is slightly higher in wild type mice than in AT2-KO mice as evaluated by TUNEL assay. Tumor vasculature number was significantly higher in AT2-KO mice than in wild type mice. In vitro co-culture studies revealed that the growth of PAN02 cells was significantly decreased when grown with AT2 receptor gene transfected wild type and AT2-KO mouse-derived fibroblasts. Faster tumor growth in AT2-KO mice may be associated with higher VEGF production in stromal cells.
  
  
  CONCLUSIONS
  These results suggest that Ang II regulates the growth of pancreatic carcinoma cells through modulating functions of host stromal cells; Moreover, Ang II AT2 receptor signaling is a negative regulator in the growth of pancreatic carcinoma cells. These findings indicate that the AT2 receptor in stromal fibroblasts is a potentially important target for chemotherapy for pancreatic cancer.
authors.affiliation: Department of Anatomy & Physiology, Kansas State University, College of Veterinary Medicine, Manhattan, KS 66506, USA.
authors.forename: Chiyo
authors.initials: C
authors.lastname: Doi
authors.forename: Noboru
authors.initials: N
authors.lastname: Egashira
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kawabata
authors.forename: Dharmendra Kumar
authors.initials: DK
authors.lastname: Maurya
authors.forename: Naomi
authors.initials: N
authors.lastname: Ohta
authors.forename: Deepthi
authors.initials: D
authors.lastname: Uppalapati
authors.forename: Rie
authors.initials: R
authors.lastname: Ayuzawa
authors.forename: Lara
authors.initials: L
authors.lastname: Pickel
authors.forename: Yuka
authors.initials: Y
authors.lastname: Isayama
authors.forename: Deryl
authors.initials: D
authors.lastname: Troyer
authors.forename: Susumu
authors.initials: S
authors.lastname: Takekoshi
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tamura
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D018920:Coculture Techniques; D015972:Gene Expression Regulation, Neoplastic; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010190:Pancreatic Neoplasms / Q000473:pathology*; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism*; D015398:Signal Transduction; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D044139:Receptor, Angiotensin, Type 2; D013778:Tetrazolium Salts; D013844:Thiazoles; D014841:von Willebrand Factor; C022616:thiazolyl blue