siRNA Targeting of MDR1 Reverses Multidrug Resistance in a Nude Mouse Model of Doxorubicin-resistant Human Hepatocellular Carcinoma.
OBJECTIVE
To investigate the effects of vector-based small interfering RNA (siRNA) targeting MDR1 on the reversal of multidrug resistance in a mouse model of doxorubicin (DOX)-resistant human hepatocellular carcinoma.


METHODS
Three siRNAs plasmid vectors (MDR1 siRNA1, MDR1 siRNA2 and MDR1 siRNA3) targeting MDR1 were constructed and transfected into DOX-resistant human hepatocellular carcinoma Bel-7402/ADM cells. The expression of MDR1 mRNA and P-glycoprotein (P-gp) was detected with RT-PCR and western blotting, respectively. A nude mouse model of DOX-resistance was established with untransfected Bel-7402/ADM or Bel-7402/ADM transfected with MDR1 siRNA (Bel-7402/ADMsi). The nude mice with tumors from untransfected Bel-7402/ADM cells were treated with either saline (Group 1); intravenous DOX (Group 2); or the combination of intra-tumoral MDR1 siRNA and intravenous DOX (Group 3). The nude mice with tumors from Bel-7402/ADMsi cells were treated with intravenous DOX (Group 4). DOX and MDR1 siRNA were administered twice a week at 20 mg/kg/dose and 9.8 mg/kg/dose, respectively. Tumor growth was measured to assess reversal of multidrug resistance by MDR1 siRNA.


RESULTS
MDRl mRNA and P-gp expression of Bel-7402/ADM cells was reduced by transfection of three siRNAs with different silencing efficiency (p<0.05). DOX treatment (Group 4) resulted in significant reduction in tumor size in the Bel-7402/ADMsi tumor model (p<0.05), indicating reversal of multidrug resistance in tumor by MDR1 siRNA. However, the combination treatment of intratumoral MDR1 siRNA and DOX (Group 3) showed no significant anti-tumor efficacy in the untransfected Bel-7402/ADM (p>0.05) tumor model, suggesting poor in vivo transfection efficiency of MDR1 siRNA. Analysis of the tumor samples showed the reduced expression level of MDR1 mRNA and P-gp was due to efficacy of MDR1 siRNA.


CONCLUSIONS
In vitro transfection of siRNAs' vectors targeting the MDR1 gene can effectively silence MDR1 mRNA and P-gp expression in DOX-resistant human hepatocellular carcinoma Bel-7402/ADM cells that resulted in reversal of multidrug resistance to DOX in the xenograft tumor model.
Anhui Medical University, Hefei, Anhui, P.R. China The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui, P.R. China.
Haitao
H
Yang
The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui, P.R. China.
Rui
R
Ding
The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui, P.R. China.
Zhong
Z
Tong
The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui, P.R. China.
Jun
J
Huang
Hefei Third People's Hospital, Hefei, Anhui, P.R. China.
Lei
L
Shen
Origin Biosciences Inc., Nanjing, Jiangsu, P.R. China.
Y U
YU
Sun
Origin Biosciences Inc., Nanjing, Jiangsu, P.R. China.
Jing
J
Liao
Origin Biosciences Inc., Nanjing, Jiangsu, P.R. China AntiCancer Inc., San Diego, CA, U.S.A.
Zhijian
Z
Yang
AntiCancer Inc., San Diego, CA, U.S.A. Department of Surgery, UCSD, San Diego, CA, U.S.A.
Robert M
RM
Hoffman
Anhui Medical University, Hefei, Anhui, P.R. China The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui, P.R. China xianglingm@medmail.com.cn wchwch3365@163.com.
Chenghong
C
Wang
Anhui Medical University, Hefei, Anhui, P.R. China The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, P.R. China xianglingm@medmail.com.cn wchwch3365@163.com.
Xiangling
X
Meng
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000235:genetics*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D034741:RNA, Small Interfering / Q000235:genetics*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D034741:RNA, Small Interfering; D004317:Doxorubicin
Multidrug resistance; P-glycoprotein; human hepatocellular carcinoma; siRNA