APPLICATION
OF MDR1 GENE THERAPY IN MALIGNANT TUMOR
Jin
XQ, Wang S, Li YC, Kang Q, Guo CB, An SH, Xu JL
Dept. of Surgery,
Children’s Hospital, Chongqing University of Medical Sciences, China
Objective: The project is to evaluate the stability
and function of mdr1 gene expression and to assess the feasibility and
safety of using mdr1 gene as bone marrow chemoprotection in patients
undergoing high-dose chemotherapy.
Methods: PA317 cells were
transfected with retrovirus vector, pHaMDR1/A which contained full-length
human mdr1cDNA, using calcium phosphate precipitation. Hematopoietic stem
progenitor cells were infected with the virious produced by PA317-HaMDR1/A
via co-culture. The effect of transfection was investigated by RT-PCR,
FACS, MTT and immunohistochemical stain method et al in vitro and vivo.
Results: 1) The transfection
ratio of human hematopoietic cells in vitro was about 35% with the
expression of bcl-2 and c-myc gene no significantly change; 2) Transferred
K562/MDR1 (ratio from 34% to 84%) cellular exogenous Pgp expression lasted
about 4 months with got 1.46-6 fold cross multidrug resistance (MDR)
phenotype in vitro; 3) mdr1 gene was successfully transferred into
hematopoietic cells of murine bone marrow, within 5 months, stable and
effective expression could be tested in murine bone marrow in vivo. The
transferred murine bone marrow cells were got 4-8 fold resistance to taxol
and CTX in vivo; 4) The hematopoietic cells of Balb/C mice with
hepatocarcinoma was transferred by mdr1 gene. Eight days later 3 in 6
Balb/C mice with mdr1 gene still lived and all of 6 in the control group
died under 2 fold CTX.
Conclusion: It is a feasible、attractive and safe way
for mdr1 gene transferring into hematopoietic cells to protect bone marrow
during high-dose chemotherapy. These results offer a basement for phase I
clinical trial.