[Dose effect of radiotherapy on drug resistance in esophageal cancer cell].
OBJECTIVE
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).


CONCLUSIONS
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.
Zhang
Guang-jian
GJ
Thoracic Surgery Department, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China. xiandocs@gmail.com
Gao
Rui
R
Zhang
Ming-xin
MX
Jin
Xin
X
Liang
Peng
P
Wang
Jian-sheng
JS
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000235:genetics; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D019583:Dose Fractionation, Radiation; D019008:Drug Resistance, Neoplasm; D004938:Esophageal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D012333:RNA, Messenger