Pyroelectric Crystal Generated Very Low Dose X-rays Enhanced the Phytotherapeutic Effects of Beta-lapachone in Hormone Dependent Prostate Cancer Cells In Vitro

In 2015, an estimated 220, 800 new cases and 27, 540 deaths are expected to occur due to prostate
cancer in US men, thus adding to the economic burden of the over 2.6 million men currently battling the
disease. Plethora of studies have demonstrated the phytotherapeutic potentials of beta-lapachone, a
phytochemical compound derived from the bark of the lapacho tree, native to South America. Betalapachone
(β-lap) has been shown to exhibit its anti-cancer effects majorly by the futile cycling between
the oxidized and the two electron reduction of β-lap mediated by NAD(P)H:quinone oxidoreductase
(NQO1) resulting in the generation of reactive oxygen species (ROS) using NADH or NAD(P) as
electron sources. β-lap is known to selectively kill human cancer cells, since NQO1 is expressed more
abundantly in numerous human solid tumors than in the adjacent normal tissues; NQO1 has been
shown to be exceptionally under expressed in hormone dependent prostate cancer cells (LNCaP)
compared to the hormone independent prostate cancer cells (PC3). This study was aimed to
investigate the enhancing effects of very low dose radiation (VLDR (20mGy)) derived from a
pyroelectric crystal generator on the phytotherapeutic activity of beta-lapachone in LNCaP cell line in
vitro accessed by MTT and Trypan blue assay. Treatment-induced intracellular levels of ROS were also
assessed using Nitro blue tetrazolium assay. NQO1 activities in LNCaP cells were also investigated
following treatment with VLDR and/or β-lap using Dicoumarol (NQO1 inhibitor). Results indicate that
LNCaP cells respond significantly to combined treatments compared to single treatments.