[Dose effect of radiotherapy on drug resistance in esophageal cancer cell].
ABSTRACT To investigate the dose effect of fractioned ionizing radiation on the expression of MDR1 in human esophageal cancer cells.
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.
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).
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.