Piperlongumine induces pancreatic cancer cell death by enhancing reactive oxygen species and DNA damage

Abstract

Pancreatic cancer is one of the most deadly cancers with a nearly 95% mortality rate. The poor response of pancreatic cancer to currently available therapies and the extremely low survival rate of pancreatic cancer patients point to a critical need for alternative therapeutic strategies. The use of reactive oxygen species (ROS)-inducing agents has emerged as an innovative and effective strategy to treat various cancers. In this study, we investigated the potential of a known ROS inducer, piperlongumine (PPLGM), a bioactive agent found in long peppers, to induce pancreatic cancer cell death in cell culture and animal models. We found that PPLGM inhibited the growth of pancreatic cancer cell cultures by elevating ROS levels and causing DNA damage. PPLGM-induced DNA damage and pancreatic cancer cell death was reversed by treating the cells with an exogenous antioxidant. Similar to the in vitro studies, PPLGM caused a reduction in tumor growth in a xenograft mouse model of human pancreatic cancer. Tumors from the PPLGM-treated animals showed decreased Ki-67 and increased 8-OHdG expression, suggesting PPLGM inhibited tumor cell proliferation and enhanced oxidative stress. Taken together, our results show that PPLGM is an effective inhibitor for in vitro and in vivo growth of pancreatic cancer cells, and that it works through a ROS-mediated DNA damage pathway. These findings suggest that PPLGM has the potential to be used for treatment of pancreatic cancer.

Transcriptome Analysis of Piperlongumine-Treated Human Pancreatic Cancer Cells Reveals Involvement of Oxidative Stress and Endoplasmic Reticulum Stress Pathways

“…In this study, our goal was to more fully understand the underlying mechanisms mediating PL-induced pancreatic cancer cell death. While we recently showed that PL inhibits pancreatic cancer progression in a mouse model by elevating ROS and enhancing DNA damage, 7 the specific events leading to DNA damage and cell death have not been previously identified.…”

“…MIA PaCa-2 cells show similar sensitivity toward PL as other commonly studied pancreatic cancer cell lines PANC-1 and BxPC3. 7 The concentration (10 lM) and duration (6 h) of PL treatment that were selected for this study do not cause significant toxicity toward healthy or cancer cells (unpublished observation). However, it is clear from the results presented in this study that significant changes in gene expression are initiated within hours of PL exposure that eventually lead to cancer cell death.…”

“…Twenty-four hours later, they were treated with 10 lM PL or with 0.1% DMSO (vehicle control) for 6 h. The time point and concentration were chosen based on our previous study reporting the induction of ROS in these cells. 7 The experiment was conducted in triplicate.…”

“…6 We recently demonstrated that piperlongumine (PL), an alkaloid present in the fruits and roots of the long pepper (Piper longum) plant, inhibits the growth of both KRAS mutant and wild-type human pancreatic cancer cell lines both in vitro and in vivo through a reactive oxygen species (ROS)-dependent mechanism that leads to DNA damage and cell death. 7 Previous studies have shown that PL selectively kills a variety of cancer cell lines with minimal death for normal cells by elevating ROS levels and inducing apoptosis. 8 Additionally, PL has been shown to cause cell cycle arrest, 9 induce autophagy, 10 and inhibit migration, 11 adhesion, and invasion.…”

Using Sensors and Generators of H2O2to Elucidate the Toxicity Mechanism of Piperlongumine and Phenethyl Isothiocyanate

“…It has been previously suggested that electrophilic small molecules such as buthionine sulfoximine (BSO), piperlongumine (PL), and phenethyl isothiocyanate (PEITC) convey at least part of their toxicity via this mechanism (9,16,39,49,51,56), and all of these drugs have been shown to be selectively toxic to certain in vitro and in vivo tumor models (1,5,13,39). Incubation of tumor cells with piperlongumine and PEITC results in depletion of GSH and elevation of fluorescence from dichloro-dihydro-fluorescein diacetate (DCFH-DA), a cell permeable dye that exhibits increasing fluorescence intensity upon oxidation (9,39,49,56). However, recent comprehensive studies involving a broader class of small molecules suggest that the depletion of GSH is often insufficient to induce death of tumor cells.…”