Induction of insulin production in rat pancreatic acinar carcinoma cells by conophylline

• Published in: Biomedicine & pharmacotherapy 2003-10, Vol.57 (8), p.341-350
• Main Authors: Umezawa, K., Hiroki, A., Kawakami, M., Naka, H., Takei, I., Ogata, T., Kojima, I., Koyano, T., Kowithayakorn, T., Pang, H.-S., Kam, T.-S.
• Format: Article
• Language: English
• Subjects: Animals; AR42J cell; Biological and medical sciences; Carcinoma, Acinar Cell - metabolism; Carcinoma, Acinar Cell - pathology; Cell Differentiation - drug effects; Cell Line, Tumor; Cell Survival - drug effects; Conophylline; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Insulin; Insulin - biosynthesis; Islets of Langerhans - drug effects; Islets of Langerhans - metabolism; Islets of Langerhans - pathology; Medical sciences; Mitogen-Activated Protein Kinases - metabolism; Neurogenin3; p38; p38 Mitogen-Activated Protein Kinases; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; Rats; Reverse Transcriptase Polymerase Chain Reaction; Smad2; Structure-Activity Relationship; Transcription Factors - biosynthesis; Vinca Alkaloids - chemistry; Vinca Alkaloids - pharmacology; β-Cell
• ISSN: 0753-3322; 1950-6007
• DOI: 10.1016/S0753-3322(03)00096-9

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 β-cell inducers among various signal transduction inhibitors. As a result, a vinca alkaloid, conophylline, induced neurite formation at 0.1∼0.3 μg/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.