Transcript Membrane b-glucuronidase - Institute of Biomedical Sciences

Membrane-anchored b-glucuronidase
Steve Roffler
Institute of Biomedical Sciences
Academia Sinica
Taipei, Taiwan
Memzyme activation of imaging or therapeutic agents
Glucuronide probe or drug
glucuronide
glucuronide
glucuronide
glucuronide
ß-glucuronidase
B7 TM Transgene Expression
MEMzyme Transgene
Potential advantage: Signal amplification due to enzymatic
hydrolysis of glucuronide probes or drugs
Potential advantages of a ßG reporter
ßG in lysosomes – inaccessible to glucuronides
Low serum ßG – little systemic activation
Low toxicity
Fast renal clearance – rapid imaging
Endogenous - low immunogenicity
Many possible glucuronide probes and drugs
In vitro imaging of gene expression
red = enzyme
expression
green = activated
probe accumulation
Fluorescent probe can be activated and accumulate
at cells that express enzyme
Imaging of adenovirus memzyme expression
Kodak IS2000MM
Sites of Ad transgene
expression could be imaged
In vitro activation of HAMG
HAMG
Glucuronide prodrug
pHAM
Active drug
COOH
O
3
H-thymidine incorporation (% control )
HO
HO
Cl
O
N
OH
HO
Cl
N
Cl
Cl
125
100
75
EJ-pHAM
EJ-HAMG
50
EJ/mbG-pHAM
EJ/mbG-HAMG
25
0
0.1
1
10
100
1000
Concentration(nM)
HAMG can be activated at EJ/mßG cells
HAMG prodrug toxicity to mice
HAMG is well tolerated by mice
Prodrug therapy of EJ tumors
(150 mg/kg HAMG on days 15 and 19)
Tumor volume (mm3)
2000
EJ
PBS
EJ HAMG
EJ/mßG PBS
EJ/mßG HAMG
1000
0
0
10
20
30
40
50
Days
HAMG displayed selective activity against EJ/mßG tumors
Summary
Surface enzyme allow both imaging and therapy
Immunogenicity is low but selectivity is high
May possess advantages for cancer gene therapy
Surface expression
Tang-Bi Liu
T cell activation
Shih-en Chang
Wen-Jun Chung
Dr. Tian-Lu Cheng
Kaohsiung Medical
University
Chin-Chuan Chen
Pei-Yu Wu
Yi-Hsuan Chiang
Chien-I Su
Dr. Hsin-Ell Wang
National Yang Ming
University
Dr. Yu-Ling Leu
Chia-Nan College of
Pharmacy and Science
Surface scFv
Dr. Kuang-Wen Liao
Shey-Cherng Tzo
Bing-Mae Chen
Dr. Ji-Wang Chern
National Taiwan
University
http://www.ibms.sinica.edu.tw/~sroff/sr_refs.html