Proteomic analysis of differentially expressed proteins in vitamin C-treated AGS cells.
BACKGROUND
Vitamin C (ascorbic acid) is an essential nutrient of most living tissues that readily acts as a strong reducing agent, which is abundant in fruits and vegetables. Although, it inhibits cell growth in many human cancer cells in vitro, treatment in cancer is still controversial. Hence, the purpose of this study was to investigate the molecular mechanism of the inhibitory effect of vitamin C on AGS cell growth, and protein profiles in AGS cells after exposure to vitamin C treatment, by using proteomic tools.


RESULTS
Vitamin C showed a cytotoxic effect on AGS cells (IC50 300 μg/mL) and, 20 differentially expressed proteins (spot intensities which show ≥2 fold change and statistically significant, p<0.05 between the control and vitamin-C treated group) were successfully identified by assisted laser desorption/ ionization-time of flight/mass spectrometry (MALDI-TOF/MS). Of the 20 proteins, six were up-regulated and fourteen were down-regulated. Specifically, 14-3-3σ, 14-3-3ϵ, 14-3-3δ, tropomyosin alpha-3 chain and tropomyosin alpha-4 chain were down-regulated and peroxiredoxin-4 and thioredoxin domain-containing proteins 5 were up-regulated. The identified proteins are mainly involved in cell mobility, antioxidant and detoxification, signal transduction and protein metabolism. Further, the expressions of 14-3-3 isoforms were verified with immuno-blotting analysis.


CONCLUSIONS
Our proteome results suggest that the apoptosis related proteins were involved in promoting and regulating cell death of AGS cells, and might be helpful to understand the molecular mechanism of vitamin C on AGS cell growth inhibition.
Research Institute of Life Science and College of Veterinary Medicine, Gyeongsang National University, 900 Gajwadong, Jinju, Gyeongnam 660-701, Republic of Korea. gonskim@gnu.ac.kr.
Arulkumar
A
Nagappan
Hyeon Soo
HS
Park
Kwang Il
KI
Park
Jin A
JA
Kim
Gyeong Eun
GE
Hong
Sang Rim
SR
Kang
Jue
J
Zhang
Eun Hee
EH
Kim
Won Sup
WS
Lee
Chung Kil
CK
Won
Gon Sup
GS
Kim
D048948:14-3-3 Proteins / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D015180:Electrophoresis, Gel, Two-Dimensional; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D054464:Peroxiredoxins / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D020543:Proteome / Q000032:analysis*; D040901:Proteomics; D015398:Signal Transduction / Q000187:drug effects; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014335:Tropomyosin / Q000378:metabolism
D048948:14-3-3 Proteins; D000975:Antioxidants; D020033:Protein Isoforms; D020543:Proteome; C498783:TPM3 protein, human; D014335:Tropomyosin; D054464:Peroxiredoxins; D019704:Protein Disulfide-Isomerases; C480743:TXNDC5 protein, human; D001205:Ascorbic Acid