| Objective This study aims to establish a MDR model of orthotopic transplantation of human hepatocellular carcinoma(HCC) in nude mice(BALB/c-nu/nu); to observe the growth, efficacy and toxicity of nude mice with As2O3 and MDR treatmented and to explore the mechanism of MDR in ude mice from the expression of clusterin (CLU), cysteine aspartate protease-3 (Caspase-3) and multidrug resistance gene -1 (MDRl) changes.Methods To establish the MDR model of orthotopic transplantation of HCC in nude mice .The nude mice were given intraperitoneal injection of ADM 8-weaks. These hepatocellular carcinoma cells resistance was determined by MTT assay.The BEL-7402/ADM hepatocellular carcinoma were transplanted into 56 nude mice liver again. After a week these nude mice were randomly divided into seven groups.①Control group: Intraperitoneal injection of NS 0.2ml.②ADM: Intraperitoneal injection of ADM 1.5mg/kg.③As2O3: Intraperitoneal injection of As2O3 1.2 mg/kg④ADM+ As2O3 (A ALow): Intraperitoneal injection of As2O3 0.8 mg/kg and ADM 1.5mg/kg.⑤ADM+ As2O3 (AAMid): Intraperitoneal injection of As2O3 1.2 mg/kg and ADM 1.5mg/kg.⑥ADM+ As2O3 (AAHigh):Intraperitoneal injection of As2O3 2.4 mg/kg and ADM 1.5mg/kg.⑦ADM+CsA: Intraperitoneal injection of CsA 2mg/kg and ADM 1.5mg/kg. These drugs were given after one week when the BEL-7402/ADM hepatocellular carcinoma were transplanted. As2O3 was used once a day,continuely a week and intermittently three weeks. ADM and CsA was administrated once a week . After 8 weaks treatment, the expressions of MDR1mRNA,CLU and Caspase-3 were observed with reverse transcriptate PCR and immunohistochemistry respectively.Results1. Through 8 weeks inducing resistance in vivo, hepatocellular carcinoma cells with positive mdrl expression showed cross drugresistance to ADM,CDDP by 13.62 and 12.97 times of IC50 as compared with negative mdrl expression respectively.2. In the group of As2O3 combined with ADM, the nude mice grow well, ascites and complications decreased significantly with in the number of drug called a separate group.3. As2O3 group inhibition rate was 10.52%, ADM Group inhibition rate is 15.35%. ADM + CsA group and the ADM + As2O3 group inhibition rate were different from ADM group.4. Expression of HCC in nude mice by immunohistochemistry. In the NS group, CLU showed strong positive expression, Caspase-3 expression was weakly positive. They were no significant difference. Compared with the control group, expression of Caspase-3 increased and expression of CLU decreased in the orthotopic transplantation of HCC was statistically significant (P <0.05). The low, middle and high doses of As2O3 + ADM group was no statistical significance.CLU and Caspase-3 expression of As2O3 group was no significant difference compared with NS group.5. Expression of MDR1 mRNA by RT-PCR was similar with the immunohistochemical results. Compared with the NS group, MDR1 mRNA levels of HCC were decreased significantly in As2O3 + ADM group (P <0.01). The low, middle and high doses of As2O3 3+ ADM group was no statistical significance. ADM group and NS group were no significant differenct (P> 0.05).Conclusions1. Successfully establish the MDR model of orthotopic transplantation of HCC in nude mice . ADM of low dose can induce MDR of HCC in nude mice .2. In As2O3 combined with ADM group, nude mice were well, weight gain was faster, orthotopic transplantation of HCC was slower and complications were fewer. Toxicity does not appear in all groups.As2O3 could significantly reversed multidrug resistance of HCC, which provide a new strategy for HCC chemotherapy.3. In vitro, As2O3 can reverse multidrug resistance of human hepatocellular carcinoma. The mechanism may be:①As2O3 can reduce the expression of MDR1mRNA;②As2O3 can promote tumor cell apoptosis by reducing the expression of CLU and increasing Caspase-3.
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