Azadirachtin Attenuates Lipopolysaccharide-Induced ROS Production, DNA Damage, and Apoptosis by Regulating JNK/Akt and AMPK/mTOR-Dependent Pathways in Rin-5F Pancreatic Beta Cells

Pancreatic inflammation and the resulting cellular responses have been implicated in pancreatitis, diabetes, and pancreatic cancer. Inflammatory responses due to the bacterial endotoxin, lipopolysaccharide (LPS), have been demonstrated to alter cellular metabolism, autophagy, apoptosis, and cell proliferation in different cell populations, and hence increases the risks for organ toxicity including cancer. The exact molecular mechanism is however not clear. In the present study, we investigated the role and mechanism of an antioxidant, azadirachtin (AZD), a limonoid extracted from the neem tree (Azadirachta indica), against LPS-induced oxidative stress in the pancreatic beta-cell line, Rin-5F. We demonstrated that cells treated with LPS (1 mu g/mL for 24 h) showed increased reactive oxygen species (ROS) production, DNA damage, cell cycle arrest, and apoptosis. Our results also showed that LPS induced alterations in the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathways, suppressing autophagy and augmenting apoptosis. Treatment with Azadirachtin (25 mu M for 24 h), on the other hand, rendered some degree of protection to the pancreatic cells from apoptosis by inducing the autophagy signals required for cell survival. These results may have significance in elucidating the mechanisms of pancreatic beta-cell survival and death by balancing the molecular communication between autophagy and apoptosis under inflammatory and pathological conditions.

Automated summary

Pancreatic inflammation caused by bacterial endotoxin lipopolysaccharide (LPS) can alter cellular metabolism, autophagy, apoptosis, and proliferation, increasing the risks for organ toxicity and cancer. This study investigated the role of the antioxidant azadirachtin (AZD) in protecting pancreatic beta-cells from LPS-induced oxidative stress, showing that AZD induced autophagy signals for cell survival. Balancing the molecular communication between autophagy and apoptosis may be crucial for pancreatic cell survival and death under inflammatory and pathological conditions.