Comparison between the effects of diallyl tetrasulfide on human retina pigment epithelial cells (ARPE-19) and HCT116 cells.
BACKGROUND
Diallyl mono- and polysulfanes from garlic are known to induce an adaptive cell response and the formation of antioxidants in cancer cells. In the case of a severe ER stress and a failure in the response, cancer cells eventually go into apoptosis. Only little is known about the response of normal cells upon treatment.


METHODS
Normal ARPE-19 cells were treated with diallyl tetrasulfide to study their cellular response and the results were compared with those of HCT116 cancer cells. Cell viability was checked by an MTT assay and cytofluorimetry. The formation of superoxide radicals, H2O2 and thiols were determined and proteins involved in the ER stress response were also detected by Western blot analysis.


RESULTS
We found that diallyl tetrasulfide induced reactive oxygen species (ROS) in normal cells similar to cancer cells in a time (0 to 60min) and dose dependent manner (0 to 50μM). The level of heme oxigenase-1 (HO-1) was up-regulated in both cell types. Initially, we found a decrease in the total thiol level in both cell types but in contrast to cancer cells, normal cells recovered from the decrease in the total thiol concentration within 60min of treatment.


CONCLUSIONS
The recovery of the thiol concentration in normal cells treated with diallyl tetrasulfide seems to be responsible for the failure to induce the ER stress signalling pathway and finally apoptosis in normal cells.


CONCLUSIONS
The difference in the recovery of the thiol status might be an explanation for the anti-carcinogenic effects of garlic compounds.
Medical Biochemistry and Molecular Biology, University of the Saarland, Building 44, 66424 Homburg, Germany.
Nathaniel Edward Bennett
NE
Saidu
Imad
I
Abu Asali
Brigitte
B
Czepukojc
Berthold
B
Seitz
Claus
C
Jacob
Mathias
M
Montenarh
D000498:Allyl Compounds / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005737:Garlic / Q000378:metabolism; D045325:HCT116 Cells; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012160:Retina / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013440:Sulfides / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D000498:Allyl Compounds; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D013440:Sulfides; D013481:Superoxides; D006861:Hydrogen Peroxide; D051547:Heme Oxygenase-1; C431585:diallyl tetrasulfide
Antioxidants; Apoptosis; ER stress signalling; Normal cells; Reactive oxygen species; Thiols