Induction of insulin production in rat pancreatic acinar carcinoma cells by conophylline.
We set up a screening system to detect low-molecular-weight compounds that induce insulin expression in pancreatic acinar carcinoma AR42J cells. They can differentiate into insulin-producing cells with neuron-like morphological change when treated with activin A. We employed this morphological change for the screening of beta-cell inducers among various signal transduction inhibitors. As a result, a vinca alkaloid, conophylline, induced neurite formation at 0.1 approximately 0.3 microg/ml in 72 h, like activin A. Conophylline-treated cells were found to express insulin as measured at both mRNA and protein levels. By RT-PCR analysis, conophylline-treated cells were shown to express neurogenin3 strongly. They also expressed Beta2/NeuroD and Nkx2.2, but not Pax4 and PP. Although activin A induces nuclear translocation of Smad2, conophylline did not. But the latter induced p38 activation, like activin A, as detected by phosphorylation. Pretreatment with a p38-specific inhibitor, SB203580, lowered the conophylline-induced insulin production. Therefore, p38 activation would be involved in the differentiation of AR42J cells into insulin-producing cells. Studies on structure-activity relationship with conophyllidine, conofoline, conophyllinine, and related monomer alkaloids showed that the dimeric aspidosperma structure with the dihydrofuran unit in its center was essential for the differentiation-inducing activity.
Faculty of Science and Technology, Department of Applied Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-0061, Japan. umezawa@applc.keio.ac.jp
K
K
Umezawa
A
A
Hiroki
M
M
Kawakami
H
H
Naka
I
I
Takei
T
T
Ogata
I
I
Kojima
T
T
Koyano
T
T
Kowithayakorn
H-S
HS
Pang
T-S
TS
Kam
D000818:Animals; D018267:Carcinoma, Acinar Cell / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000090322:Homeobox Protein Nkx-2.2; D007328:Insulin / Q000096:biosynthesis*; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000096:biosynthesis; D014748:Vinca Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases
D000090322:Homeobox Protein Nkx-2.2; D007328:Insulin; C000715628:Nkx2-2 protein, rat; D014157:Transcription Factors; D014748:Vinca Alkaloids; C099167:conophylline; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases