title: Antitumor activity of TGF-beta inhibitor is dependent on the microenvironment.
abstract: Pancreatic cancer is one of the deadliest forms of cancer and effective treatment remains a clinical challenge. Transforming growth factor-beta (TGF-beta) has important roles in primary tumor progression and in promoting metastasis, and has become an attractive target for therapy. Previously, we reported that treatment of pancreatic cancer cells in vitro with SD-208, a small molecule inhibitor of the TGF-beta receptor I kinase (TGF-betaRI), inhibited expression of genes associated with tumor progression and inhibited invasiveness in a cell-based assay. In a demonstration of efficacy of TGF-beta signaling inhibition in an in vivo model of pancreatic cancer, we showed significantly reduced primary tumor weight and decreased incidence of metastasis in the Panc-1 orthotopic xenograft model of established pancreatic cancer. In this report, we extend these in vivo findings to examine the mechanistic consequences of TGF-betaRI inhibition on Panc-1 primary tumors and their microenvironment in situ. In a longitudinal study of TGF-betaRI inhibition in the Panc-1 orthotopic model, we show that SD-208 treatment significantly reduced tumor growth measured as bioluminescence intensity throughout the study. Histological evaluation revealed that SD-208 treatment reduced proliferation and induced apoptosis in the primary tumors, and reduced fibrosis in the tumor microenvironment. An immune contribution (greater B-cell infiltration in SD-208-treated tumors) was also suggested by the histological analyses. SD-208 not only blocked direct TGF-beta signaling in Panc-1 primary tumors (reduced phospho SMAD2/3), but also down-regulated the expression of TGF-beta-regulated genes (PAI-1 and COL7A1). Taken together, our results indicate that a TGF-betaRI kinase inhibitor has a potential therapeutic benefit for pancreatic cancer patients.
authors.affiliation: Scios Inc., Fremont, CA 94555, USA. satya.medicherla@spcorp.com
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Medicherla
authors.forename: Lingyun
authors.initials: L
authors.lastname: Li
authors.forename: Jing Ying
authors.initials: JY
authors.lastname: Ma
authors.forename: Ann M
authors.initials: AM
authors.lastname: Kapoun
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Gaspar
authors.forename: Yu-Wang
authors.initials: YW
authors.lastname: Liu
authors.forename: Ruban
authors.initials: R
authors.lastname: Mangadu
authors.forename: Gilbert
authors.initials: G
authors.lastname: O'Young
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Protter
authors.forename: George F
authors.initials: GF
authors.lastname: Schreiner
authors.forename: Darren H
authors.initials: DH
authors.lastname: Wong
authors.forename: Linda S
authors.initials: LS
authors.lastname: Higgins
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics; D011621:Pteridines / Q000494:pharmacology*; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors*; D023041:Xenograft Model Antitumor Assays
chemical_list: D047428:Protein Kinase Inhibitors; D011621:Pteridines; D018125:Receptors, Transforming Growth Factor beta; C511004:SD-208; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I