The Research On The Relationship Between MicroRNA-21and Human Breast Cancer Cell In Radiation Sensitivity

Objective：Detect the expression of miR-21by the real-time quantitative RT-PCR methodin three different radiation sensitivity breast cancer cell lines,and set up miR-21highexpression and low expression breast cancer cell model respectively,research therelationship between microRNA-21and human breast cancer cell in radiationsensitivity and explore X-Ray radiation effects on miR-21expression.Methods：1. Set up the three normal breast cancer cells,extracted RNA, use the real-timequantitative RT-PCR method to detect the expression of miR-21.2.3Gy X-Ray irradiate the breast cancer cells,detected the expression of miR-21byreal-time quantitative RT-PCR at0,4,8,12and24h respectively,To determine the timeeffect on the expression of miR-21after X-Ray radiated.3.0Gy,1.0Gy,2.0Gy,4.0Gy and6.0Gy X-Ray irradiated the breast cancer cells,detected the expression of miR-21by real-time quantitative RT-PCR at24hrespectively,To determine the dose effect on the expression of miR-21after X-Rayradiated.4. To establish the dose-effect curve of the three normal breast cancer cell： X-Rayirradiated the cells (0Gy,1.0Gy,2.0Gy,4.0Gy,6.0Gy,dose rate：0.363Gy/min), use thecolony formation assay to detect cell survival fraction，Giemsa staining method tovalidate repeatedly.5. Refer to the instruction of LipofectamineTM2000liposome,to transfected themiR-21mimic and miR-21mimic NC into the breast cancer cell MCF7and MDA-MB-231,set up miR-21high expression cell line and the miR-21mimic NC was thecontrol group.X-Ray irradiated cells (0Gy,1.0Gy,2.0Gy,4.0Gy,6.0Gy,dose rate： 0.363Gy/min) after24hours,use the colony formation assay to detect cell survivalfraction,Giemsa staining method to validate repeatedly.and detected the expression ofmiR-21by real-time quantitative RT-PCR.6. Refer to the instruction of LipofectamineTM2000liposome,to transfected themiR-21inhibitor and miR-21inhibitor NC into the breast cancer cell MCF7andMDA-MB-231, set up miR-21low expression cell line and the miR-21inhibitorNC was the control group.X-Ray irradiated cells (0Gy,1.0Gy,2.0Gy,4.0Gy,6.0Gy,dose rate：0.363Gy/min) after24hours,use the colony formation assay to detect cellsurvival fraction,Giemsa staining method to validate repeatedly.and detected theexpression of miR-21by real-time quantitative RT-PCR.Results：1. The expression of miR-21in the three normal breast cancer cellsUse the real-time quantitative RT-PCR to detect the expression of miR-21in thethree normal breast cancer cells,we found that compared with the cell MDA-MB-231,the expression of miR-21is higher than its in the cell MCF7andMDA-MB-435s(P<0.05);and the expression of miR-21in the MCF7is higher than itsin the cell MDA-MB-435s(P<0.05).2. The time effect on the expression of miR-21after X-Ray radiated.After3Gy X-Ray radiated，the expression of miR-21in the breast cancer cellsMDA-MB-231showed a trend of rise(P<0.05);After3Gy X-Ray radiated the breastcancer cells MCF7,the expression of miR-21decreased at first,then graduallyincrease，but it began to decline at24h(P<0.05).3. The dose effect on the expression of miR-21after X-Ray radiated.Different doses of X-Ray irradiated the breast cancer cells,and detect theexpression of miR-21after24h,we found that compared with the0Gy group,theexpression of miR-21in the cell MDA-MB-231increased with the irradiation doseand reached the highest expression at4.0Gy, then began to decrease(P<0.05);Compared with the0Gy group in breast cancer cell MCF7,the expression of miR-21in1.0Gy,2.0Gy and4.0Gy increased(P<0.05),the expression of miR-21in6.0Gy group decreased(P<0.05).4. The radiation sensitivity relationship between the three normal breast cellCompare the radiation sensitivity relationship between the three normal breastcell by the colony formation assay,we found that the sensitivity of breast cancer cellsMDA-MB-435s is higher than MCF7cells,and the MCF7radiation sensitivity ishigher than the MDA-MB-231.5. The changes of radiation sensitivity after transfected miR-21mimic into the breastcancer cellsAfter transfected miR-21mimic into the breast cancer cells MCF7,comparedwith miR-21mimic NC group and normal group,the radiation sensitivity decreased;After transfected miR-21mimic into the breast cancer cells MDA-MB-231，comparedwith miR-21mimic NC group and normal group,the radiation sensitivity alsodecreased.6. The changes of radiation sensitivity after transfected miR-21inhibitor into thebreast cancer cellsAfter transfected miR-21mimic into the breast cancer cells MCF7,comparedwith miR-21inhibitor NC group and normal group,the radiation sensitivity increased;After transfected miR-21mimic into the breast cancer cells MDA-MB-231,comparedwith miR-21inhibitor NC group and normal group,the radiation sensitivity alsoincreased.Conclusion：The expression of miR-21is different in the different radiation sensitivity breastcancer cells,and it can produce certain influence to the radiation sensitivity,whenmake the miR-21high expression,it can decrease the radiation sensitivity of the breastcancer cells, In the opposite,it can make radiation sensitivity increase; And the timeeffect and the dose effect of X-Ray radiation can also affect the expression of miR-21.