Capsaicin (CAP), the pungent ingredient of chili peppers, inhibits growth of various solid cancers via TRPV1 as
well as TRPV1-independent mechanisms. Recently, we showed that TRPV1 regulates intracellular calcium level
and chromogranin A secretion in pancreatic neuroendocrine tumor (NET) cells. In the present study, we
characterize the role of the TRPV1 agonist – CAP – in controlling proliferation and apoptosis of pancreatic
BON and QGP-1 NET cells. We demonstrate that CAP reduces viability and proliferation, and stimulates
apoptotic death of NET cells. CAP causes mitochondrial membrane potential loss, inhibits ATP synthesis
and reduces mitochondrial Bcl-2 protein production. In addition, CAP increases cytochrome c and cleaved caspase
3 levels in cytoplasm. CAP reduces reactive oxygen species (ROS) generation. The antioxidant N-acetyl-L-cysteine
(NAC) acts synergisticallywith CAP to reduce ROS generation,without affecting CAP-induced toxicity. TRPV1 protein
reduction by 75% reduction fails to attenuate CAP-induced cytotoxicity. In summary, these results suggest
that CAP induces cytotoxicity by disturbing mitochondrial potential, and inhibits ATP synthesis inNET cells. Stimulation
of ROS generation by CAP appears to be a secondary effect, not related to CAP-induced cytotoxicity. These
results justify further evaluation of CAP in modulating pancreatic NETs in vivo.
Capsaicin (CAP), the pungent ingredient of chili peppers, inhibits growth of various solid cancers via TRPV1 aswell as TRPV1-independent mechanisms. Recently, we showed that TRPV1 regulates intracellular calcium leveland chromogranin A secretion in pancreatic neuroendocrine tumor (NET) cells. In the present study, wecharacterize the role of the TRPV1 agonist – CAP – in controlling proliferation and apoptosis of pancreaticBON and QGP-1 NET cells. We demonstrate that CAP reduces viability and proliferation, and stimulatesapoptotic death of NET cells. CAP causes mitochondrial membrane potential loss, inhibits ATP synthesisand reduces mitochondrial Bcl-2 protein production. In addition, CAP increases cytochrome c and cleaved caspase3 levels in cytoplasm. CAP reduces reactive oxygen species (ROS) generation. The antioxidant N-acetyl-L-cysteine(NAC) acts synergisticallywith CAP to reduce ROS generation,without affecting CAP-induced toxicity. TRPV1 proteinreduction by 75% reduction fails to attenuate CAP-induced cytotoxicity. In summary, these results suggestthat CAP induces cytotoxicity by disturbing mitochondrial potential, and inhibits ATP synthesis inNET cells. Stimulationof ROS generation by CAP appears to be a secondary effect, not related to CAP-induced cytotoxicity. Theseresults justify further evaluation of CAP in modulating pancreatic NETs in vivo.
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