EGF-induced proliferation of adult human pancreatic duct cells is mediated by the MEK/ERK cascade

Abstract

Human postnatal pancreatic duct cells are a potential source of new beta cells. Factors regulating proliferation of human pancreatic duct cells in vitro are unknown. In several other cell types, this process is influenced by ligands of the ErbB receptor family. The expression and functionality of the ErbB family members and their possible role in duct cell proliferation were determined. In cultured adult human pancreatic duct cells the different members of the ErbB family (ErbB1-4) were present at transcript and protein level. Stimulation of the duct cells with epidermal growth factor (EGF) and betacellulin results in Tyr-phosphorylation of ErbB1 and ErbB2, followed by activation of Shc, MEK1/2 and ERK1/2. Duct cells with activated ErbB signaling changed morphology and motility. EGF induced proliferation of a fraction of the duct cells and treatment with PD98059 prevented Ki67 expression in EGF-supplemented cells. When transduced with recombinant adenovirus expressing constitutively activated MEK1, duct cells proliferate and spread even in the absence of EGF. Importantly, the adult human duct cells retain their capacity to recapitulate ngn3-induced embryonic (neuro)endocrine differentiation after proliferation. Therefore, the present data support a possible role for human adult pancreatic duct cells, following expansion and transdifferentiation, as a source of insulin by transplantation to type I diabetes patients.

Betacellulin inhibits amylase and glucagon production and promotes beta cell differentiation in mouse embryonic pancreas

“…Addition of EGF and TGFα promoted branching morphogenesis and reduced amylase expression in cultured pancreatic buds as expected, but neither factor reduced the number of glucagon-positive cells (data not shown). Pancreases of EGFR-deficient mice show impaired ductal branching, suggesting that this phenotype is mediated, in part, by the activation of a common EGFR downstream signalling pathway, possibly the MEK/ERK pathway [21,27]. However, in contrast to betacellulin and TGFα action, EGF reduced the number of insulin-positive beta cells (data not shown), as previously reported [28].…”

Epidermal growth factor induces adult human islet cell dedifferentiation

“…We hypothesized that the effect of EGF in this system was likely the activation of the latter two kinases, as these are known to act downstream of EGF binding (Rescan et al 2005, Miettinen et al 2006. Moreover, the effect of EGF on pancreatic tissue appears to be the induction of cellular dysplasia and proliferation (Wagner et al 1998, Means et al 2005.…”

“…Following RNA extraction, as per the manufacturer's protocol, cDNA was reverse transcribed using an Omniscript RT kit (Qiagen). Custom primers (Invitrogen) were synthesized (Table 2; Adam et al 1999, Rescan et al 2005, and quantitative realtime PCR was performed using a QuantiTect SYBR green RT-PCR kit (Qiagen) in a MJ Research DNA Engine Opticon 2 (Bio-Rad). Expression levels were normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and expressed relative to pre-treatment controls.…”

“…Several EGF ligands have been reported as b-cell mitogens (Huotari et al 1998), with BTC postulated as a signaling intermediate for the mitogenic effects of glucagonlike peptide-1 (Buteau et al 2003). However, EGF ligands are not only mitogenic to endocrine cells but also induce duct cell proliferation (Vinter-Jensen et al 1997, Rescan et al 2005, Suarez-Pinzon et al 2005a. In fact, this latter effect appears to prime duct cells for islet regeneration.…”

Clinical Islet Cell Transplantation – Recent Advances

“…Therefore, the potential for conversion of pancreatic ductal cells towards an endocrine cells remains unclear. Moreover, previous studies have revealed only a limited proliferative capacity of primary human pancreatic ductal cells in culture 78 . Thus, despite their relative abundance, multiple practical issues have prevented the development of human pancreatic ductal cells as a source of replacement beta-cells.…”