TAIP induces apoptosis in hepatocellular carcinoma-derived cells
Klaas Kooistra
Biological Chemistry, Molecular GeneticsLIC, Leiden University
LC Workshop Proteins killing Tumour CellsNovember 1, 2007
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
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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 …..
Miyata et al. 1999
Apoptin
TAIP
GC-rich region
SP-1 site
Poly(A) site
TATA box
TTV-strain has CAV-like genomic organization
TTV: torque teno virusCAV: chicken anemia virus
TAIP
Apt
TAIP
Apt
TAIP
Apt
TAIP amino acid sequence shows “similarities” with apoptin’s
Hydrophobic a.a. stretches; Proline distribution; Thr/Ser-rich
Expression of TAIP in human tumor cells
Putative TTV-derived TAIP of 105 a.a.
Approach0.36 kb Myc-TAIP DNA was synthesized (Midland, USA) Cloned in pCMV-expression vector
15 kD
TAIP production in COS-1 cells
TAIP
IFA / HUH-7 cells
TAIP DNA
apoptin apoptin DNA
Cytoplasmic TAIP inducesapoptosis in HUH-7 cells
Transient transfection of three human hepatocellular carcinoma (HCC) cell lines
TAIP
Apoptin
Lac Z
5 days post transfection
TAIP induces apoptosis human HCC cells
Transient transfection of three non-HCC cell lines
TAIP induces much less apoptosis in non-HCC
TAIP
Apoptin
Lac Z
5 days post transfection
TAIP-induces apoptosis in HCC significantlymore than in non-HCC
TAIP
Apoptin
Lac Z
Preliminary results: TAIP does not induce apoptosisin normal rat hepatocytes
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 (?)
Conclusions
TAIP functions differently than apoptin?!
Acknowledgements
Ying-Hui ZhangNiek HendriquezBertram Weiss
Dominik MumbergMathieu Noteborn
Thank you for your attention
1. Miyata et al., Identification of a novel GC-rich 113-nucleotide region to complete the circular, single-stranded 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.
Literature of interest