| Malignant tumor has become serious disease which threats human beings. Nasopharyngeal Carcinoma (NPC) is one of the most common cancer in ENT department, radiotherapy is one of the most important methods to treat it, but the effect is not good. The main obstacles are the existance of multidrug resistance and the different sensitivity which different individual owns. Clinical multidrug resistance is recognized in patients after treated with radiotherapy. NPC HNE-1 cell line was chosed to carry out the study. Multidrug resistant HNE-1 (200) subline was derived from HNE-1 cell line after exposed to fractionated X-irradiation. By means of MTT, 4 kinds of common anti-cancer medicines, oxymatrine as well as green tea (polyphenoles) were used to detective the inhibitive rate of twokinds of cells in the field of cell proliferation. The result was as followed:Every kind of substances was capable of inhibiting cell proliferation of two cell lines at different degree.1) Below the 20% inhibition rate, the concentrations of vincristine were 25ug/ml and 50ug/ml. Furthermore, under the concentrations of 75ug/ml, 100ug/ml and 125ug/ml, the inhibitive effect of vincristine was more stronger on HNE-1 than HNE-l(200) subline. This indicated that HNE-1 (200) was resistance to vincristine after exposed to fractionated X-irradiation.2) Below the 20% inhibition rate, the concentrations of bleomycin were 20ug/ml and 40ug/ml. Under the same concentrations, bleomycin had stronger inhibitive effect on HNE-1 than HNE-l(200) subline. This indicated that HNE-l(200) was resistance to bleomycin after exposed to fractionated X-irradiation.3) 5-Fu could suppressed cell growth of both kinds of cell lines. The inhibitive effect increased gradually as the increase concentrations of 5-Fu, there was no significantly difference between the both cells in inhibitive effect.4) Cisplatin could also suppress both kinds of cell lines, there was no significant difference between the both cells, just like 5-Fu.5) Verapamil, oxymatrine had the same effect as 5-Fu and cisplatin oninhibiting cell growth. 6) Catechin, epicatechin had no signs of suppress effect to both cell lines.In order to know the reversal information of medicines to HNE-1(200) cell, seven medicines with low cell inhibitive concentrations were used and had present different degree of reversal effects on HNE-1 (200) cell line. The result is:1) The drug-drug interaction could all increase the inhibition effect on two cell lines.2) Verapamil, oxymatrine, catechin, epicatechin were capable of interaction with 4 kinds of anti-cancer drugs respectively and give rise to the reversal effect to vincristine and bleomycin in HNE-l(200) cell.In order to understand the mechanism of multidrug resistance, we examined the expression of P-glycoprotein by means of immunochemical method, Western blot, RT-PCR and the changes of cell cycle in different situation by FCM.Immunochemical method showed that the P-glycoprotein expression in HNE-1 cell was negative while HNE-l(200) was positive. This implied that cells exposed to fractionated X-irradiation can result in the increasing of P-glycoprotein in the HNE-l(200) subline.Western blot also showed that HNE-1(200) cell expressed P-glycoprotein negative while HNE-1(200) positive. This result wascoincidence with the one of immunochemical method.RT-PCR prompts that there was no significant difference between HNE-1 and HNE-1(200) subline in increasing of P-glycoprotein mRNA. This implied that P-glycoprotein overexpression was not associated with an increase in P-glycoprotein mRNA in this irradiated HNE-lcells. In other words, maybe the P-glycoprotein has been modulated with another mechanism, but not only mRNA. Through FCM, we find that:(1) After exposed to fractionated X-irradiation, the cell of in G2 stage increased in amount.(2) VCR+VRP and VCR+Oxy could decrease the proportion of cells in G2 phase and result in the death of the cells.(3) VCR+EC and VCR+catechin were capable of...
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