The Effects Of Prunella Vulgaris On Expression Of Mdr1 Gene Of Tumor Cells

Background and ObjectiveAccording to the report of WHO,the year 2000 saw that malignancynant tumor death cases reached a startling point of 7 million around the world,which constituted an average12%of all the death cases with the 9%in developing countries and 21%in developed countries.As a developing country,China's malignancynant tumor death cases has,among all the causes,a 19%as its percentage.At present,chemotherapy is still the major means to treat malignancynant tumor patients.Athough new chemotherapy drugs and new programs have been used in the clinical,MDR is the major cause leading to the failure of tumor chemicaltherapy,and is also the major problem in tumor theatment.Multidrug resistance(MDR) here means that the tumor cells develop cross tolerance against different drugs with different structure and mechanism of action when they begin to resist one drug.The formative mechanism of drug resistance is very complicated and tumor cells could have different ways to develop MDR,and one kind of MDR cells could have many kinds of resistance mechanisms at the same time. Based on the investigation data from the society of malignancynant tumor USA,90% of the 49 million death cases of malignancy experienced the drug resistance in different levels.Therefore,to explore the mechanism of the emerging of MDR and seek the reversal agent and method against the multidrug resistance has been becoming a hot researching issue all over the world. In recent years,verapamil(VER),frequently studied reversal agent of drug resistance,and technology of antisense RNA,antisense oligonucleotide,ribozyme and gene knock-out thechnique backed gene reversion method all have been limited in the clinical application for the reason of toxical side effect,high cost or high degree of difficulty.Promisingly,as the our national treatures,chinese herb medicine has a long history of curing the cancer,with its merits of "low cost,little toxicity,big safety margin,strong broad spectrum and more effective target points" to be a reveral agent, which pulling more and more attentions in the researching of MDR.Records and reports have proved that herb medicine has the biological active constitutent,and flavonoids,tetrandrine,peimine,panaxoside,arsenic disulfide,elemene and other compound herb recipe also has the potency to reverse the MDR effect in vitro,which indicates all the better that herb medicine has a potential clinical application and value of exploitation,and thus deserving our deeper research.Prunella vulgaris here refers to the dry ripe ear of brunellae cum fructu, belonging to labiatae and Prunella,which has the effectiveness of eyesight improving and endogenous fire clearing,detumescence and stagnation eliminating,this will help to restrain the proliferation of many kinds of tumor cells and to induce apoptosis, however,it is rarely reported about the researching on its reversal effect of multidrug resistance.Zhou Xinying,an graduate student from China medical university,had done some some research and proved that PV can partly reverse the drug fast of breast cancer tumor cells,but similar report has not yet been seen on the research about reversal effect on Raji cells,MDA-MB-435s cells and SMMC-7721 cells.This research is aimed to use the RT-PCR technology and observe the effect on genetic expression of multidrug resistance in Raji cells,MDA-MB-435s cells and SMMC-7721 cells under different concentrations of PV,and in this way,to approach the mechanism of MDR with the expectation to find the potential drug fast reversal medicine with clinical application prospect.METHODS1 The half inhibitory rate(IC₅₀) of Raji cells,MDA-MB-435s cells and SMMC-7721 cells treated with ADM,and ADM in combination with PV were examined by MTT assay,respectively.2 The effects of different concentrations of Prunella vulgaris on expression of mdr1 gene of Raji cells,MDA-MB-435scells and SMMC-7721 cells were detected with reverse transcriptase polymerase chain reaction(RT-PCR).RESULTS1 PV cytotoxicity detection,the depressant effects on Raji cells,MDA-MB-435s cells and SMMC-7721 cells bear a dose-concentration dependence.Through the dose effect curve,non-cytotoxicity dose(growth rate＞95%) could be determined as 10.0μg/ml,20μg/ml and 30μg/ml.The IC₅₀ of three tumor cells dealed with PV were 31.67±0.89μg/ml,63.03±1.22μg/ml,81.45±2.16μg/ml respectively.The IC₅₀ of three tumor cells dealed with ADM were 1.28±0.66μg/ml,1.87±0.85μg/ml,2.39±1.58μg/ml.We choose the PV of non-cytotoxicity dose combinedwith ADM at its correspondingly different levels of concentrations.The experimental results show that values of IC50 have significant difference(P＜0.05) between the conditions when ADM was solely used against the tumor cells and used with the combination of Prunella vulgaris.2 The effects of Prunella vulgaris on expression mdr1 gene of tumor cells,from the rusult of study,we can see Raji cells,MDA-MB-435s cells and SMMC-7721 cells exprssion mdr1 gene,the mdr1 gene expression of SMMC-7721 cells were strongest, the mdr1 gene expression of were weakest,which were in line with the degree of resistance of three tumor cells in the clinical.Different concentrations of PV could weaken the expression level of mdr1 gene of Raji cells,MDA-MB-435s cells and SMMC-7721 cells,and with the concentration increasing,the down regulation of expression were more obvious(P＜0.05).CONCLUSION1 PV can inhibit Raji cells,MDA-MB-435s cells and SMMC-7721 cells proliferation,and the inhibition were dose-dependent.2 PV is able to partly reverse the ADM-resistance in Raji cells,MDA-MB-435s cells and SMMC-7721 cells.3 Three tumor cells have been existed primary multidrug resistance,mdr1 gene over-expression of tumor cells may be the formation of the molecular basis of MDR4 Different concentrations of PV which under the non-cytotoxic dose could reverse or partly reverse the multidrug resistance by way of weaken the expression level of mdr1 gene.