The Reversing Effect Of Arsenic Trioxide On Multidrug Resistance Of Human Hepatocellular Carcinoma Cells In Vivo

Objective This study aims to investigate the multidrug resistance reversal effects of arsenic trioxid(As₂O₃) on onxenografts derived from multi-drug resistant hepatocellular carcinoma (HCC)cell line BEL-7404/ADM and the possible mechanism by detecting the expression of multidrug resistance-assoctated protein(MRP) and glucosylceramide synthase(GCS).Methods Subcutaneous tumors of the BEL-7402 hepatoma cells were transplanted into nude mice and given intraperitoneal injection of adriamycin 8W. These liver tumor cells urvivalrate was determined by MTT assay.The BEL-7402/ADM hepatoma cells were transplanted into 56 nude mice liver again. After a week these nude mice were randomly divided into seven groups.â‘ Control group: Intraperitoneal injection of NS 0.2ml.â‘¡ADM: Intraperitoneal injection of ADM 1.5mg/kg.â‘¢As₂O₃: Intraperitoneal injection of As₂O₃ 1.2 mg/kgâ‘£ADM+ As₂O₃ (AALow):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.â‘¥ADM+ As₂O₃ (AAHigh):Intraperitoneal injection of As₂O₃ 2.4 mg/kg and ADM 1.5mg/kg.⑦CsA: Intraperitoneal injection of CsA 2mg/kg and ADM 1.5mg/kg. These drugs were given after one week when the BEL-7402/ADM hepatoma cells were transplanted. As₂O₃ was used once a week, intermittently three weeks. ADM and CsA was administrated eight weekly. After treatment ,the expressions of MRPmRNA and GCS were observed with reverse transcriptate PCR and immunohistochemistry respectively.Results1.BEL-7402/ADM cells were resistant to many anti-tumor agents . The IC50 of ADM and CDDP were 13.62 and 12.97 times higher than that of BEL-7402.But the BEL-7402/ADM cells'resistance to MMC and 5-FU was not obvious.2. These nude mice which were administrated with ADM or As₂O₃ alone had a high number of ascites(P = 0.026) and peritoneal transfers(P = 0.035) than which were given united drugs.3. As₂O₃ group inhibition rate was 10.68%, ADM Group inhibition rate was 22.65%.For this drug-resistant cell lines, the two kinds of chemical drugs didn't have the basic role in tumor suppression. Low, middle and high As₂O₃ united ADM groups tumor weight in nude mice were significantly lower than ADM group. The inhibitory rate of CsA group and the United As₂O₃ chemotherapy groups (A CsA group: 64.96%, A AHigh3: Group 67.52%, A AMid2 group: 66.24% , A ALow1 group:54.7%)had no significant difference (P> 0.05), but these groups had a have in a big way suppress the tumor function comperd with the ADM group and As₂O₃ group(P<0.05). As₂O₃ with ADM showed synergy, (q = 2.14, P = 0.015).4. ADM Group had a strongest expression of MRPmRNA than other groups,and the expression of MRPmRNA in the three co-adminstration group were lower than in ADM group and NS group(P<0.01),but the three co- adminstration groups had no significant differences between them,and it also happed to As₂O₃ group and ADM group(P>0.05).5. Immunohistochemistry showed that GCS can be found in each group. The tumors of ADM group showed a strong positive expression of GCS, was significantly higher than other groups(P<0.01). A low-dose chemotherapy of ADM can enhance the positive rate of GCS. These co- adminstration groups can be reduced the expression of GCS in vivo tumor, like with CsA group(P<0.01). Although the three groups had a increasing expression of GCS , but without statistical significance(P>0.05).Conclusions1. A low doses of ADM chemotherapy could induce BEL-7402 cells increased resistance, with the use of cycles increased, the tumor cells resistant gene and protein can be a strong positive.2. As₂O₃ can reverse multidrug resistance of human hepatoma carcinoma in vivo, with is associated with decreasing the expression of MRPmRNA and GCS and increasing intra-cellular drug cumulant.3. This phenomenon that As₂O₃ showed a strong effect of reversal of multidrug resistance in liver cancer provided us a new way of clinical treatment of liver cancer.