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TAIP induces apoptosis in
hepatocellular carcinoma-derived cells
Klaas Kooistra
Biological Chemistry, Molecular Genetics
LIC, Leiden University
LC Workshop Proteins killing Tumour Cells
November 1, 2007
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A specific TT virus strain has a CAV-like genome
TTV protein (TAIP) harbors apoptin-like characteristics?
• Amino-acid sequence similarities?
• Apoptosis?
TAIP-studies in human tumor cell lines
Specific TT virus (TTV) strain
TT viruses belong to human circoviridae
• Single stranded circular DNA virus
Within TT viruses a very high genetic variability exists
TTV strain (GenBank: AB008394) described by Miyata
• Isolated from Japanese patient with non-A-E hepatitis
Attracted our specific attention for …..
TTV-strain has CAV-like genomic organization
TAIP
GC-rich region
Apoptin
SP-1 site
Poly(A) site
TATA box
TTV: torque teno virus
CAV: chicken anemia virus
Miyata et al. 1999
TAIP amino acid sequence shows
“similarities” with apoptin’s
TAIP
Apt
TAIP
Apt
TAIP
Apt
Hydrophobic a.a. stretches; Proline distribution; Thr/Ser-rich
Expression of TAIP in human tumor cells
Putative TTV-derived TAIP of 105 a.a.
Approach
0.36 kb Myc-TAIP DNA was synthesized (Midland, USA)
Cloned in pCMV-expression vector
15 kD
TAIP production in COS-1 cells
TAIP
TAIP
DNA
Cytoplasmic TAIP induces
apoptosis in HUH-7 cells
apoptin
apoptin
IFA / HUH-7 cells
DNA
TAIP induces apoptosis human HCC cells
5 days post
transfection
TAIP
Apoptin
Lac Z
Transient transfection of three human hepatocellular carcinoma
(HCC) cell lines
TAIP induces much less apoptosis in non-HCC
5 days post
transfection
TAIP
Apoptin
Lac Z
Transient transfection of three non-HCC cell lines
TAIP-induces apoptosis in HCC significantly
more than in non-HCC
TAIP
Apoptin
Lac Z
Preliminary results: TAIP does not induce apoptosis
in normal rat hepatocytes
Conclusions
TAIP induces p53 independent apoptosis
TAIP induces apoptosis preferentially in HCC cells
TAIP is localized in the cytoplasm in cancer cells
TAIP non-toxic for normal cells (?)
TAIP functions differently than apoptin?!
Acknowledgements
Ying-Hui Zhang
Niek Hendriquez
Bertram Weiss
Dominik Mumberg
Mathieu Noteborn
Thank you for your attention
Literature of interest
1. Miyata et al., Identification of a novel GC-rich 113nucleotide region to complete the circular, singlestranded DNA genome of TT virus, the first human
circovirus.
J Virol. 1999 May;73(5):3582-6.
2. Kooistra et al., TT virus-derived apoptosis-inducing
protein induces apoptosis preferentially in hepatocellular
carcinoma-derived cells.
J Gen Virol. 2004 Jun;85(Pt 6):1445-50.
3. Hino and Miyata, Torque teno virus (TTV): current status.
Rev Med Virol. 2007 Jan-Feb;17(1):45-57.