BACKGROUND: In recent years, nano-carriers have been regarded as the most promising
technologies for breakthrough the bottleneck of
gene transfer. Polyamidoamine
dendrimer (PAMAM) is a kind of new nanometer material. PAMAM can transfer target
gene to the
cell with high
efficiency and lower toxic both in vivo and
in vitro .
OBJECTIVE: To evaluate the antitumour effects of
survivin antisense oligonucleotide (
Survivin -asODN) carried by PAMAM on
colorectal cancer transplanted subcutaneously in
nude mice .DESIGN,
TIME AND
SETTING: An in vivo experiment regarding
tumor gene therapy was performed from February to August in 2008 at the
Laboratory of Bionanometer
Engineering ,
Research Institute of Micro/nanometer
Science &
Technology of Shanghai Jiao Tong
University and Central
Laboratory of Zhujiang
Hospital of Southern Medical
University .MATERIALS
Human colorectal cancer cells SW620 were from Shanghai
Cell Institute of
Chinese Academy of
Sciences .PAMAM
dendrimer was offered by the Bionanometer
Engineering Laboratory ,
Research Institute of Micro/nanometer
Science &
Technology , Shanghai Jiao Tong
University . Lipofectamine ~(TM)2000 was purchased from Invitrogen, USA.
Survivin -asODN was synthesized by Shanghai
Bioengineering Company.
METHODS: The PAMAM and
cation liposome were respectively mixed with
Survivin -asODN to generate the
transfection complex
carrying antisense
gene . The shape of the complex was observed by
transmission electron microscope, the
particle size was determined by
laser particle size analysator and the
zeta potential was measured by an analytical tool. The encapsulating
efficiency and release progress
in vitro were determined by ultraviolet spectrophotometer in centrifuging
method .
Human colorectal cancer cells SW620 at logarithmic phase were inoculated into the abdominal region of 18 Blab/C
nude mice subcutaneously to produce transplanted
tumor models in
colorectal cancer nude mice , which were randomly divided into 3 groups
liposome , PAMAM and blank
control groups . They were injected respectively with Hposome-
survivin -asODN complex,PAMAM-
survivin -as ODN
transfection complex and seroculture liquid. The volumes of
tumor were surveyed in the 2 groups.
Western blotting method was used to determine the
survivin gene expression in the transplanted
tumor tissue .MAIN OUTCOME
MEASURES: Particle size ,
zeta potential ,
gene loading level, encapsulation
efficiency , release rate of cationic
liposome -
survivin -asODN complex and PAMAM-
survivin -asODN complex, as well as
survivin expression rate and
apoptosis rate after
transfection , inhibition rate of the transplanted
tumor growth ,
Survivin protein expression and activity in the transplanted
tumor cells .
RESULTS: The
particle size of PAMAM-
survivin -asODN complex was smaller (P < 0.01), but the
zeta potential was greater (P < 0.05), compared with
liposome -
survivin -asODN. There was no significant difference between PAMAM and
liposome groups in terms of
gene loading rate and
transfection efficiency .
DNA release lasted for 14 days for PAMAM, but only 5 days for
liposome .After
colorectal cancer cell transfection ,
survivin protein expression was lower, but
apoptosis rate was higher, in the PAMAM-
survivin -asODN complex than in the
liposome -
survivin -asODN complex (P < 0.05).
CONCLUSION: PAMAM facilitates delivery of
Survivin -asODN into transplanted
colorectal cancer cells SW620. As a result,
survivin protein expression was decreased, and
apoptosis rate was increased in vivo which inhibited transplanied tumour
growth .