Project description:Aberrant acinar to ductal metaplasia (ADM), one of the earliest events involved in exocrine pancreatic cancer development, is typically studied using pancreata from transgenic mouse models. We used primary, human pancreatic acinar cells to evaluate the transcriptional profile during the course of ADM.
Project description:Acinar ductal metaplasia (ADM), is believed to be one of the earliest precursor lesions towards the development of pancreatic ductal adenocarcinoma, and maintaining the pancreatic acinar cell phenotype suppresses tumor formation. We report that pStat3 and HDAC inhibition can attenuate ADM in vitro and TSA treatment reverses the dedifferentiated phenotype to one that is more acinar. Our findings suggest that pharmacological inhibition or reversal of pancreatic ADM represents a potential therapeutic strategy for blocking ductal reprogramming of acinar cells.
Project description:Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease when diagnosed at a late stage, however patient survivorship significantly increases when the disease is detect prior to metastasis. To study the earliest events leading to PDAC initiation, we developed a genetically engineered mouse model of PDAC utilizing a tamoxifen-inducible Cre Recombinase knocked into the transcription factor Ptf1a locus to induce expression of oncogenic KrasG12D and Trp53R270H alleles in adult pancreatic acinar cells. Mice of the genotype KrasLSL-G12D/+; Trp53LSL-R270H/+; Ptf1aCreERTM/+ (KPT) developed PDAC following tamoxifen injection while control Cre recombinase negative KrasLSL-G12D/+; Trp53LSL-R270H/+; (KP) mice injected with tamoxifen did not develop PDAC. Acinar cells comprising the pancreata of tamoxifen treated KPT mice we observed to undergo acinar to ductal metaplasia (ADM), and formed precancerous lesions. We used laser capture microdissection (LCM) and RNA sequencing to generate, to our knowledge, the first transcriptional profile of an enriched population of metaplastic acinar cells in situ. Comparing the transcriptional profile of metaplastic acinar cells with the transcriptional profile of healthy pancreatic tissue identified differentially expressed genes associated with ADM. Ingenuity pathway analysis revealed transcriptional regulators and canonical signaling pathways involved in ADM. LCM was used to generate a transactional profile of cancer cells isolated from pancreatic tumors, and differential gene expression analysis revealed a subset of genes which are overexpressed in both ADM and PDAC relative to healthy pancreas. Further analysis of genes expressed in both pancreatic cancer precursor ADM lesions and invasive PDAC may lead to the identification of novel biomarkers of PDAC.
Project description:This study describes a novel function for the ST6GAL1 sialyltransferase in promoting acinar to ductal metaplasia (ADM). ST6GAL1 activity facilitates ADM by reprogramming acinar cells into a more progenitor-like state.
Project description:In order to compare the gene expression profile of acinar-to-ductal metaplasia (ADM), ductal and acinar cells in the setting of pancreatitis, which were obtained by laser-capture microdissection (LMD) from frozen sections of wild type mice pancreata 2 days after caerulein administration, we performed microarray analysis. ADM has an intermediate property between ductal and acinar cells in the setting of pancreatitis, and Cxcr4 mRNA which is expressed in multipotent pancreatic progenitors, were up-regulated in ADM compared with ductal cells or acinar cells. Notably, in consistent with our immunostaining data, Dclk1 mRNA was highly expressed in ADM cells compared with ductal and acinar cells.
Project description:To investigate the underlying changes during acinar-to-ductal metaplasia, pancreatic acinar cells were isolated from 5 week old KrasG12D-mice. RNA was isolated immediately after isolation (t=0 days) or after 3 days embedded in collagen.
Project description:Pancreatic ductal adenocarcinoma (PDAC) is the most important histological subtype of pancreatic cancer, accounting for approximately 90% of all pancreatic cancers.Acinar to ductal metaplasia (ADM) is a recently recognized, yet less well-studied, precursor lesion of PDAC developed in the setting of chronic pancreatitis. Through digital spatial mRNA profiling, we compared ADM and adjacent PDAC tissues from patient samples to unveil the bridging genes, bridging signaling pathway and bridging molecular function during the malignant transformation of pancreatitis.
Project description:Oncogenic KrasG12D, a driver mutation of pancreatic ductal adenocarcinoma (PDAC), induces neoplastic transformation of acinar cells through acinar-to-ductal metaplasia (ADM). Here, we show that both functional complexes of mTOR (mechanistic target of rapamycin kinase, mTORC1 and mTORC2) are specifically activated in ADM. Murine models uncover that mTORC1 and mTORC2 cooperate to promote KrasG12D-driven ADM development. Proteomic analyses identify Arp2/3 complex, an actin nucleator, as the common downstream effector: mTORC1 is responsible for the protein synthesis of Rac1 and Arp3 while mTORC2 promotes the Arp2/3 complex activity via Akt/Rac1 signalling. Genetic ablation of Arp2/3 complex completely arrests KrasG12D-driven ADM development. The Arp2/3 complex-mediated y-branching of actin network promotes the basolateral spread of filamentous actin, which is indispensable for acinar cells-initiated carcinogenesis. Induced by oncogenic KrasG12D, ADM is a metaplastic phenotype of acinar cells that requires extensive actin rearrangements. mTORC1 and mTORC2, downstream targets of KrasG12D, have well-established oncogenic functions in PDAC development. The actin-related protein 2/3 (Arp2/3) complex is the first identified actin nucleator. Regarded as textbook knowledge, it is activated by EGFR/Rac1 signalling to promote the polymerisation of branched actin filaments from pre-existing filaments in numerous biological contexts. Hereby, we identify that mTORC1 and mTORC2 attain a dual, yet non-redundant, regulatory role in promoting Arp2/3 complex function, which is responsible for generating basolateral filamentous actin in ADM. Thus, the role of Arp2/3 complex fills up the missing gap between putative oncogenic signals and actin dynamics underlying PDAC initiation.