F. Zhu, Y. Guan and R. Zhang Pages 668 - 676 ( 9 )
Background: Linoleic acid has been implicated in the pathogenesis of acute pancreatitis. However, molecular mechanisms underlying adverse effects of large-dose linoleic acid remain unclear. Current study aimed to explore the impact of high-dose linoleic acid on the activation of Janus kinase 2 (JAK2)-signal transducers and activators of transcription 3 (STAT3) pathway, cytokine production, and lipogenesis in pancreatic exocrine cells.
Methods: MTT assay was used to detect the viability of AR42J rat pancreatic exocrine cells, and lactate dehydrogenase assay was utilized to detect cytotoxicity. Concentrations of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were detected by ELISA, and protein expression of JAK2, p-JAK2, STAT3, p- STAT3, and fatty acid synthase (FAS) was examined by Western Blot. The impact of highdose linoleic acid on JAK2-STAT3 pathway was also examined when JAK2 was inhibited by AG490, and STAT3 expression was interrupted by siRNA.
Results: The cell viability of AR42J rat pancreatic exocrine cells was inhibited, and cytotoxicity was increased by high-dose linoleic acid. JAK2 and STAT3 proteins in pancreatic exocrine cells were activated by high-dose linoleic acid via phosphorylation and nuclear localization of phosphorylated STAT3. Moreover, the expression of downstream proteins in JAK2-STAT3 pathway (IL-6, TNF-α and FAS) was up-regulated by high-dose linoleic acid. The increased levels of IL-6 and TNF-α caused by high-dose linoleic acid were attenuated by JAK2 inhibitor AG490. p-JAK2 protein was up-regulated, whereas p-STAT3, STAT3 and FAS proteins were down-regulated by high-dose linoleic acid in the presence of STAT3-siRNA.
Conclusion: The cytotoxicity was increased and JAK2-STAT3 signaling pathway was activated by high-dose linoleic acid through cytokine production and lipogenesis in rat pancreatic exocrine cells.
JAK2, STAT3, linoleic acid, cytokines, fatty acid synthase.
Department of Gastroenterology, Shanghai East Hospital, Shanghai Tongji University School of Medicine, No. 150 Jimo Road, Pudong New District, Shanghai 200120, China.