title: Characterization of somatostatin receptor expression in human pancreatic cancer using real-time RT-PCR.
abstract: BACKGROUND
  Somatostatin inhibits cell proliferation and may act as a tumor suppressor by interacting with five different somatostatin receptors (SSTRs). We hypothesized that SSTR expression is down-regulated in human pancreatic cancer. In the current study, we used a powerful real-time RT-PCR technique to examine the mRNA expression levels of all five SSTR subtypes in human pancreatic cancer.
  
  
  METHODS
  Total RNA was extracted from three pancreatic cancer cell lines (Panc-1, MIA PaCa-2, and Hs 766T), three surgical specimens of pancreatic cancer, and adjacent pancreatic tissue, and a pancreatic cancer cell line transfected with the SSTR-2 gene. Specific primers were designed and mRNA levels for the five SSTRs were analyzed with real-time quantitative RT-PCR using a Bio-Rad iCycler system.
  
  
  RESULTS
  The pancreatic tumor specimens had a 2.5- and 4.3-fold reduction of SSTR-2 and SSTR-5 mRNA levels, respectively, as compared to their adjacent normal pancreatic tissues. SSTR-1 and SSTR-3 were also detected in both the cancer specimens and the adjacent tissues, but SSTR-4 was absent. Human pancreatic cancer cell lines also expressed SSTR-2 and SSTR-5 mRNA, but not SSTR-1, SSTR-3, and SSTR-4. Up-regulation of SSTR-2 mRNA by 2.2 x 10(4)-fold in Panc-1 cells resulted in receptor expression and growth inhibition.
  
  
  CONCLUSIONS
  Expression of SSTR-2 and SSTR-5 could be important in the growth inhibitory effect of somatostatin in human pancreatic cancer. Down-regulation of SSTR transcription or SSTR mRNA instability may result in loss of a tumor suppressive effect of SSTRs in human pancreatic cancer.
authors.affiliation: Elkins Pancreas Center and Molecular Surgeon Research Center, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Hee Joon
authors.initials: HJ
authors.lastname: Kim
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yao
authors.forename: Changyi
authors.initials: C
authors.lastname: Chen
authors.forename: William E
authors.initials: WE
authors.lastname: Fisher
mesh_terms: D000230:Adenocarcinoma; D045744:Cell Line, Tumor; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D010190:Pancreatic Neoplasms; D012333:RNA, Messenger / Q000032:analysis; D017481:Receptors, Somatostatin / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*
chemical_list: D012333:RNA, Messenger; D017481:Receptors, Somatostatin; C103631:somatostatin receptor 3; C101130:somatostatin receptor type 1; C094573:somatostatin receptor 5; C093733:somatostatin receptor 2