The Effects Of Blocking The HENT_s In Pancreatic Cancer Cell Menbrane On The Cytotoxicity Of 5-Fluorouracil

Objective: To study the effects and the mechanism of the hENTS blocker on the cytotoxicity of 5-Fluorouracil (5-FU) to pancreatic cancer cell lines.Methods: mRNA expressions of hENT1, hENT2, hCNT1, hCNT2 and hCNT3 in Panc-1, Sw1990 and Aspc-1 pancreatic cancer cell lines were investigated by RT-PCR. Cell lines were incubated in 96 wells plate. Then, each cell line was divided into DP treated group and control group. The DP treated group was further divided into two subgroups according to the DP concentration, the 5μM subgroup and the 10μM subgroup. After cells incubated in the medium with 5-FU in a serial concentrations for 48 hr, cell proliferation in each group was determined with MTT assay and the IC50 was calculated. To investigate the effect of DP combined with 5-FU on cell apoptosis and cell cycle distribution in Panc-1 cells, cells were also divided into 3 groups with the same DP serial, and incubated in 5-FU with the doubled concentration of the IC50 calculated in control group for 24 hr. Cell apoptosis and cell cycle were detected with flow cytometer.Results: MTT showed 5-FU inhibited cell proliferation, which was enhanced by DP in Panc-1 and Sw1990 cell lines, while not in Aspc-1 cell line. The differences were correlated to the expression of hENTS in the three cell lines. Panc-1 and Sw1990 cell lines expressed high levels of hENTS, in contrast, Aspc-1cell line expressed low hENT1 and no hENT2. In comparision to control group, IC50 in 10μM DP group decreased 7 times in Panc-1 and 10 times in Sw1990 (P < 0.01), no change was found in Aspc-1. The apoptosis assay and the cell cycle detected by flow cytometer suggested 5-FU induced the apoptosis and reduced the percentage of S-phase cells, which was enhanced by DP blocking hENTS in Panc-1 cells, Apoptosis was induced 1.80 times (P < 0.01) and the percentage of S-phase cells reduced to 74.06 % (P < 0.05) in 10μM DP group.Conclusion: In pancreatic cancer cell lines, DP could significantly enhance the cytotoxicity of 5-FU by blocking hENTS transporters, which depends on the high expressions of hENT1 and hENT2.