Dexamethasone Treatment Induces the Reprogramming of Pancreatic Acinar Cells to Hepatocytes and Ductal Cells

The pancreatic exocrine cell line AR42J-B13 can be reprogrammed to hepatocytes following treatment with dexamethasone. The question arises whether dexamethasone also has the capacity to induce ductal cells as well as hepatocytes.AR42J-B13 cells were treated with and without dexamethasone and analyzed for the expression of pancreatic exocrine, hepatocyte and ductal markers. Addition of dexamethasone inhibited pancreatic amylase expression, induced expression of the hepatocyte marker transferrin as well as markers typical of ductal cells: cytokeratin 7 and 19 and the lectin peanut agglutinin. However, the number of ductal cells was low compared to hepatocytes. The proportion of ductal cells was enhanced by culture with dexamethasone and epidermal growth factor (EGF). We established several features of the mechanism underlying the transdifferentiation of pancreatic exocrine cells to ductal cells. Using a CK19 promoter reporter, we show that a proportion of the ductal cells arise from differentiated pancreatic exocrine-like cells. We also examined whether C/EBPβ (a transcription factor important in the conversion of pancreatic cells to hepatocytes) could alter the conversion from acinar cells to a ductal phenotype. Overexpression of an activated form of C/EBPβ in dexamethasone/EGF-treated cells provoked the expression of hepatocyte markers and inhibited the expression of ductal markers. Conversely, ectopic expression of a dominant-negative form of C/EBPβ, liver inhibitory protein, inhibited hepatocyte formation in dexamethasone-treated cultures and enhanced the ductal phenotype.These results indicate that hepatocytes and ductal cells may be induced from pancreatic exocrine AR42J-B13 cells following treatment with dexamethasone. The conversion from pancreatic to hepatocyte or ductal cells is dependent upon the expression of C/EBPβ

Transdifferentiation of pancreatic AR42J-B13 cells to hepatocyte and ductal phenotypes

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Among Other Tissues, Short-Term Garlic Oral Treatment Incrementally Improves Indicants of Only Pancreatic Islets of Langerhans Histology and Insulin mRNA Transcription and Synthesis in Diabetic Rats

Background: The source, mRNA transcription, and synthesis of insulin in the pancreas, in addition to the bile duct and liver, in streptozotocin (STZ)-induced diabetic rats (DR) in response to garlic oral treatment are not yet clear. Objective: This study investigated the accumulative effects of continued garlic oral treatment on changes in the pancreas, bile duct, and liver with regards to: 1—Insulin mRNA transcription, synthesis, and concentration in relation to changes in serum insulin (SI); 2—Insulinogenic cells insulin intensity and distribution, proliferation, and morphology. Method: Fasting blood glucose (FBG) and insulin concentration in serum and pancreas (PI) and sources and mRNA transcription in the pancreas, bile duct, and liver in normal rats given normal saline (NR-NS) and DR given either NS (DR-NS) or garlic extract (DR-GE) before and after 1, 4, and 8 weeks of oral treatment were examined. Results: Compared to NR-NS, DR-NS showed a significant increase in FBG and reductions in SI and PI and deterioration in islets histology, associated pancreatic insulin numerical intensities, and mRNA transcription. However, compared to DR-NS, the targeted biochemical, histological, and genetic variables of DR-GE were significantly and incrementally improved as garlic treatment continued. Insulin or its indicators were not detected either in the bile duct or the liver in DR-GE. Conclusions: 8 weeks of garlic oral treatment is enough to incrementally restore only pancreatic islets of Langerhans insulin intensity and insulinogenic cells proliferation, morphology, and distribution. These indices were associated with enhanced pancreatic insulin mRNA transcription and synthesis. Eight weeks of garlic treatment were not enough to stimulate insulinogenesis in either the bile duct or the liver

Expression Profiling of <i>Pdx1</i>, <i>Ngn3</i>, and <i>MafA</i> in the Liver and Pancreas of Recovering Streptozotocin-Induced Diabetic Rats

Studies in animal diabetic models have demonstrated the possibility of islet regeneration through treatment with natural extracts, such as Allium sativum (garlic). This study aimed to investigate the effect of garlic extract (GE) on the expression of three genes (Ngn3, Pdx1, and MafA) in the pancreas and liver of diabetic rats. Thirty-two rats were divided into two groups, streptozotocin (STZ)-induced diabetic rats (n = 16) and healthy rats (n = 16). Both groups were subdivided into GE-treated (n = 8), and those administered 0.9% normal saline (NS) (n = 8) for 1 week (n = 4) and 8 weeks (n = 4). In the pancreas of diabetic rats treated with GE for 1 week, all three genes, Ngn3, Pdx1, and MafA, were significantly upregulated (p ≤ 0.01, p ≤ 0.05, and p ≤ 0.001, respectively) when compared to diabetic rats treated with NS only. However, after eight weeks of GE treatment, the expression of all three genes decreased as blood insulin increased. In the liver, only Pdx1 expression significantly (p ≤ 0.05) increased after 8 weeks. The significant expression of Ngn3, Pdx1, and MafA in the pancreas by week 1 may have induced the maturation of juvenile β-cells, which escaped the effects of STZ and caused an increase in serum insulin

Schematic representation of the possible pathways of differentiation of B13 cells into hepatocytes and ductal cells.

<p>Diagram illustrating the potential relationship between pancreatic acinar cells, ductal cells and hepatocytes.</p

Electron microscopy and stability of the ductal phenotype.

<p>(A) Electron micrographs of control, Dex and Dex/EGF treated B13 cells. (B) Immunostaining for amylase, CK20 and CK7 following withdrawal of Dex and EGF in treated B13 cells. Control B13 cells are also shown (B). Scale bars for electron micrographs are (from left to right); 2, 2, 1 and 0.5 µm. Scale bars in second row, 20 µm and 40 µm for all others.</p

CEBPβ controls the switch in phenotype from pancreatic B13 cells to hepatocyte or ductal cells.

<p>Immunostaining for C/EBPβ/TFN and C/EBPβ/PNA in control, Dex and Dex/EGF treated cells (A) and after infection with Ad-CMV-LAP (B) and Ad-CMV-LIP (C). In A only the induced endogenous C/EBPβ is visible. Scale bars, 20µ m.</p

Lineage trace of ductal phenotype.

<p>(A) Infection of HepG2, control B13 and Dex/EGF treated B13 cells with Ad-CK19-nucGFP and (B) immunostaining for amylase and TFN in Dex/EGF treated B13 cells infected with Ad-CK19-nucGFP.</p

Expression of ductal markers and inhibition of the ductal phenotype.

<p>(<b>A</b>) RT-PCR for Cx43 and GSTπ (B) Western blotting analysis for Albumin, TFN, AFP and the liver enriched transcription factor C/EBPβ in control, EGF, Dex/EGF and Dex treated cells. β-actin and α-tubulin are also shown as loading controls. (C) Immunostaining for CK7 in control and Dex/EGF treated cells in the presence and absence and absence of the EGF receptor inhibitor AG1478. The inhibitor was added at a final concentration of 25 µM.</p