Aim: To investigate the dose effect of fractioned ionizing radiation on the expression of MDR1 in human esophageal cancer cells.
Methods: The mRNA and protein levels of MDR1 in esophageal cancer cell line EC9706 incubated in culture containing 150 micromol/L CoCl(2); pre- and post-irradiation were measured by quantitative reverse transcription-polymerase chain reaction (QRT-PCR) and Western blot analysis, respectively. The chemo-sensitivity was analyzed by MTT.
Results: Comparing with the control group, hypoxia culture significantly induced MDR1 expression (P<0.05). After 20 fractions of irradiation, the MDR1 expression was significantly up-regulated in 2 Gy/d.f group (P<0.05), while obviously decreased in 1 Gy/d.f group (P<0.05). Consequently, the cell inhibitory rate was significantly reduced in 2 Gy/d.f group, but increased in 1 Gy/d.f group (P<0.05).
Conclusion: These results indicate that MDR1 is differentially modulated by different doses of fractionated radiation, which should be taken into account when combining radiotherapy chemotherapy for esophageal cancer patients.