ObjectiveTo investigate the effects of dipyridamole (DP), one of the human equilibrative nucleoside transporters (hENTs) blockers, on 5-fluorouracil (5-FU) induced cell apoptosis and cell cycle changes of the pancreatic cancer Panc-1 cell line. MethodsPancreatic cancer cell line Panc-1 was divided into hENTs blocked group and hENTs unblocked group. The hENTs blocked group was further divided into two subgroups according to the DP concentration, 5 μmol/L DP group and 10 μmol/L DP group. Each group was incubated in culture medium with or without 1.5×106 ng/L 5-FU for 24 h. Cell apoptosis and cell cycle were detected by flow cytometry. Results①The apoptosis results of each group： Incubated in culture medium with 1.5×106 ng/L 5-FU for 24 h, the apoptosis rates of 5 μmol/L DP group and 10 μmol/L DP group were higer than those of hENTs unblocked group （Plt;0.05）, and which of 10 μmol/L DP group was higer than that of 5 μmol/L DP group (Plt;0.05). Incubated in culture medium without 5-FU for 24 h, there were no significant differences of the apoptosis rates among three groups (Pgt;0.05). ②The cell cycle results of each group: Incubated in culture medium with 1.5×106 ng/L 5-FU for 24 h, the percentages of S phase cells in the 5 μmol/L DP group and 10 μmol/L DP group were less than those of hENTs unblocked group (Plt;0.05). The percentage of S phase cell of 5 μmol/L DP group reduced to 87.09% and that of 10 μmol/L DP group reduced to 74.06% as compared with hENTs unblocked group. 5-FU had little influence on G2 phase (Pgt;0.05) except for the percentage of G2 phase cells in the 5 μmol/L DP group increased significantly (Plt;0.05) as compared with the hENTs unblocked group. Incubated in culture medium without 5-FU for 24 h, there were no significant differences of the cell cycles among three groups (Pgt;0.05). ConclusionsIn pancreatic cancer Panc-1 cell, DP could enhance the cytotoxicity of 5-FU by blocking hENTs. The enhanced cytotoxicity is related to elevation of 5-FU concentration in cells, and unrelated to DP itself.
ObjectiveTo investigate the effect of expressions of nucleoside transporters subtype (hENT1 and hENT2) on 5-fluorouracil(5-FU) cytotoxicity in breast cancer cell lines(MDA-MB-231, MDA-MB-468, SK-BR-3, MCF-7). MethodsFour breast cancer cell lines were chosen to detect the mRNA expressions of hENT1 and hENT2 by RT-PCR. Cells were incubated in the medium with a serial concentrations of 5-FU from 1.28×104 ng/L to 2.00×108 ng/L for 48 h. Then the cell proliferation in each cell line was measured by MTT assay and the IC50 was evaluated. Results①The mRNA expressions of hENT1 and hENT2 in the MDA-MB-231, MDA-MB-468, or SK-BR-3 cells were significantly higher than thoes in the MCF-7 cells(P < 0.05). The mRNA expression of hENT2 was detected in the MDA-MB-231, MDA-MB-468, or SK-BR-3 cells, not detected in the MCF-7 cells. 2MTT showed that IC50 of 5-FU in the MDAMB-231, MDA-MB-468, or SK-BR-3 cells was significantly lower than that in the MCF-7 cells(P < 0.05). There was no statistical difference of IC50 among the three lines(MDA-MB-231, MDA-MB-468, and SK-BR-3)(P > 0.05).③The three lines(MDA-MB-231, MDA-MB-468, and SK-BR-3) with lower IC50 of 5-FU highly expressed hENTs, and MCF-7 cell with the higher IC50 of 5-FU expressed less hENTs. ConclusionsThe expressions of hENTs in breast cancer cell lines can significantly influence 5-FU cytotoxic effect. It is implicated that the hENTs expressions might be the clue to the choice of nucleoside anticancer drugs in clinic.