title: Inactivation of TIF1gamma cooperates with Kras to induce cystic tumors of the pancreas.
abstract: Inactivation of the Transforming Growth Factor Beta (TGFbeta) tumor suppressor pathway contributes to the progression of Pancreatic Ductal AdenoCarcinoma (PDAC) since it is inactivated in virtually all cases of this malignancy. Genetic lesions inactivating this pathway contribute to pancreatic tumor progression in mouse models. Transcriptional Intermediary Factor 1 gamma (TIF1gamma) has recently been proposed to be involved in TGFbeta signaling, functioning as either a positive or negative regulator of the pathway. Here, we addressed the role of TIF1gamma in pancreatic carcinogenesis. Using conditional Tif1gamma knockout mice (Tif1gamma(lox/lox)), we selectively abrogated Tif1gamma expression in the pancreas of Pdx1-Cre;Tif1gamma(lox/lox) mice. We also generated Pdx1-Cre;LSL-Kras(G12D);Tif1gamma(lox/lox) mice to address the effect of Tif1gamma loss-of-function in precancerous lesions induced by oncogenic Kras(G12D). Finally, we analyzed TIF1gamma expression in human pancreatic tumors. In our mouse model, we showed that Tif1gamma was dispensable for normal pancreatic development but cooperated with Kras activation to induce pancreatic tumors reminiscent of human Intraductal Papillary Mucinous Neoplasms (IPMNs). Interestingly, these cystic lesions resemble those observed in Pdx1-Cre;LSL-Kras(G12D);Smad4(lox/lox) mice described by others. However, distinctive characteristics, such as the systematic presence of endocrine pseudo-islets within the papillary projections, suggest that SMAD4 and TIF1gamma don't have strictly redundant functions. Finally, we report that TIF1gamma expression is markedly down-regulated in human pancreatic tumors by quantitative RT-PCR and immunohistochemistry supporting the relevance of these findings to human malignancy. This study suggests that TIF1gamma is critical for tumor suppression in the pancreas, brings new insight into the genetics of pancreatic cancer, and constitutes a promising model to decipher the respective roles of SMAD4 and TIF1gamma in the multifaceted functions of TGFbeta in carcinogenesis and development.
authors.affiliation: INSERM, U590, IFR62, Lyon, France.
authors.forename: David F
authors.initials: DF
authors.lastname: Vincent
authors.forename: Kai-Ping
authors.initials: KP
authors.lastname: Yan
authors.forename: Isabelle
authors.initials: I
authors.lastname: Treilleux
authors.forename: Fabien
authors.initials: F
authors.lastname: Gay
authors.forename: Vanessa
authors.initials: V
authors.lastname: Arfi
authors.forename: Bastien
authors.initials: B
authors.lastname: Kaniewski
authors.forename: Bastien
authors.initials: B
authors.lastname: Kaniewsky
authors.forename: Julien C
authors.initials: JC
authors.lastname: Marie
authors.forename: Florian
authors.initials: F
authors.lastname: Lepinasse
authors.forename: Sylvie
authors.initials: S
authors.lastname: Martel
authors.forename: Sophie
authors.initials: S
authors.lastname: Goddard-Leon
authors.forename: Juan L
authors.initials: JL
authors.lastname: Iovanna
authors.forename: Pierre
authors.initials: P
authors.lastname: Dubus
authors.forename: Stéphane
authors.initials: S
authors.lastname: Garcia
authors.forename: Alain
authors.initials: A
authors.lastname: Puisieux
authors.forename: Ruth
authors.initials: R
authors.lastname: Rimokh
authors.forename: Nabeel
authors.initials: N
authors.lastname: Bardeesy
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Scoazec
authors.forename: Régine
authors.initials: R
authors.lastname: Losson
authors.forename: Laurent
authors.initials: L
authors.lastname: Bartholin
mesh_terms: D000818:Animals; D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016147:Genes, Tumor Suppressor; D006801:Humans; D051379:Mice; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C511956:TRIM33 protein, human; D014157:Transcription Factors; C491420:Trim33 protein, mouse; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras)