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