Allicin, an extremely active constituent of freshly crushed garlic, is produced upon reaction of substrate
alliin with the
enzyme alliinase (EC 4.4.1.4).
Allicin has been shown to be toxic to several mammalian cells in vitro in a dose-dependent manner. In the present study this cytotoxicity was taken to advantage to develop a novel approach to
cancer treatment, based on site directed generation of
allicin.
Alliinase was chemically conjugated to a
monoclonal antibody (mAb) which was directed against a specific
pancreatic cancer marker, CA19-9. After the CA19-9 mAb-
alliinase conjugate was bound to targeted
pancreatic cancer cells (MIA PaCa-2 cells), on addition of
alliin, the
cancer cell-localized
alliinase produced
allicin, which effectively induced apoptosis in MIA PaCa-2 cells. Specificity of anticancer activity of in situ generated
allicin was demonstrated using a novel in vitro system-integrated discrete multiple organ co-culture technique. Further,
allicin-induced
caspase-3 expression, DNA fragmentation, cell cycle arrest, p21(Waf1/Cip1)
cyclin-dependent kinase inhibitor expression, ROS generation, GSH depletion, and led to various epigenetic modifications which resulted in stimulation of apoptosis. This approach offers a new therapeutic strategy, wherein
alliin and
alliinase-bound antibody work together to produce
allicin at targeted locations which would reverse gene silencing and suppress
cancer cell growth, suggesting that combination of these targeted agents may improve
pancreatic cancer therapy.