Identification of triosephosphate isomerase as an anti-drug resistance agent in human gastric cancer cells using functional proteomic analysis.

AIMS: Proteomic study was used to explore new multidrug resistance (MDR)-related proteins and clarify novel mechanism of MDR in gastric cancer.
METHODS: Two-dimensional gel electrophoresis and the PDQuest software analysis were applied to compare the differential expression of MDR-related proteins in gastric cancer SGC7901 cells and drug-resistant SGC7901 cells (SGC7901/VCR) induced by vincristine sulfate (VCR). The differential protein dots were excised and further analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis (MALDI-TOF-MS).
RESULTS: Nine differential expression proteins between the two cell lines were successfully identified by MALDI-TOF-MS. Triosephosphate isomerase (TPI), a glycolytic pathway enzyme, was identified as a downregulated protein in SGC7901/VCR cells. Further, Western blot analysis and semiquantitative RT-PCR confirmed its decreased expression in SGC7901/VCR cells. Sense vector pcDNA3.1-TPI was constructed and transfected into SGC7901/VCR. The sensitivity of TPI-SGC7901/VCR cells to adriamycin (ADR), VCR, 5-fluorouracil and cis-dichlorodiamine platinum, as well as the accumulation and retention to ADR, were significantly increased when compared to their control cell lines.
CONCLUSIONS: These results provide new MDR-related protein candidates, which are differentially expressed in the MDR cell line and its parental cell line including TPI, which may participate in the VCR-mediated MDR in human gastric cancer. Upregulation of TPI expression could partially reverse multidrug-resistant phenotype of SGC7901/VCR, which suggests that TPI may be an anti-drug resistance agent in gastric cancer and the candidate target to develop novel therapeutics for better treatment of gastric cancer.