In vitro investigation on therapeutic potential of juglone, a naphthoquinone from walnuts against pancreatic cancer

Abstract

Juglone, a naphthoquinone found in Juglandaceae family, which includes black walnut, European walnut, and butter nut possess various biological activities. The anti-cancer properties of juglone has been reported; however, the effect of juglone in pancreatic cancer (PC) has not been elucidated yet. PC is an aggressive lethal, highly metastatic disease associated with poor prognosis and high mortality rate. PC is usually diagnosed in advanced stage and chemotherapy is provided as a first line of treatment. The de novo chemoresistance that develops with chemotherapeutic treatment creates a critical need for identification of novel therapeutic agents for effectively targeting the disease. The effects of juglone on PC cell proliferation, level of reactive oxygen species (ROS) production, and expression of various oncogenic signal transduction molecules in MIA Paca-2, pancreatic carcinoma cells were investigated. The major findings indicate that treatment with juglone dose dependently suppressed the in vitro proliferation and induced cell death of rapidly dividing human PC cells with an IC50 value of 5 μM at 24 h. Long-term colonies forming ability of PC cells was also significantly inhibited. The molecular mechanisms behind juglone-induced apoptosis of PC cells indicated activation of caspase-3, cleavage of PARP, upregulation of Bax, down regulation of Akt, ERK, HER-2, Cox-2, and Bcl-2 and very high production of ROS leading to chromatin condensation, DNA damage and cell death. Changes in morphological features of cell treated with juglone were obtained by confocal microscopy using Hoechst staining, which specified apoptotic features in treated cells. The results also revealed the anti-angiogenic and anti-metastatic potential of juglone. PC cell migration and invasion was significantly reduced with juglone treatment and the potential of endothelial cells to form tubes was also limited when treated with juglone. Key angiogenic regulators such as HIF-1α and VEGF were also downregulated with juglone treatment. Taken together, our data suggest that of ROS-inducing agent juglone could provide a novel therapeutic approach for PC treatment.