ABSTRACTS – ORAL PRESENTATIONS - AMCA, spol. s r.o.

P42. ELUCIDATION OF CROSSTALK BETWEEN SENESCENCE AND APOPTOSIS
Zuzana Nahacka, Gita Novakova, Ladislav Anděra
Institute of Molecular Genetics of the Academy of Science of Czech Republic, Laboratory
of Cell Signaling and Apoptosis, Prague, Czech Republic, nahackaz@img.cas.cz
Senescence is irreversible cell-cycle arrest, where senescent cells stay metabolically
active and acquire distinctive morphological and biochemical alterations (Bartek et al.,
2007). Replicative senescence was described in normal cells as an intrinsic molecular
programme that limits cell multiplication (Hayflick and Moorhead, 1961). Apart from
aging, senescence in normal human cells can be induced by oncogenes such as activated
H-Ras as a protective measure against tumorigenesis. Furthermore stress-induced or
premature senescence is one of the major cellular response to chemotherapy and
radiotherapy in solid tumors (Mirzayans et al., 2005).
The other type of cell protection against tumorigenesis is apoptosis. In our study we are
mainly interested in an elucidation of presumed crosstalk between apoptotic signaling
and senescence-triggered rewiring the cellular signaling and metabolism.
We induced premature senescence in primary (colorectal NCM460) and cancer cell
lines (pancreatic PANC and mestohelial H28) with BrdU (20-100uM) treatment for 5-7
days. Then using mainly flow cytometry we analyzed response of senescent cells to
different apoptotic stimuli inducing extrinsic (Trail, Fas ligand) or intrinsic (mito-VES,
staurosporine, campthotecin) apoptotic signaling and the expression profile of TRAIL-R1
(Death receptor 4), TRAIL-R2 (Death receptor 5), TRAIL-R3 (Decoy receptor 1), TRAIL-R4
(Decoy receptor 2), FAS and TNF receptors. In addition to drug-induced senescence
we are currently testing recombinant lentiviruses with inducible (pLVX p16-T2A-p21)
or constitutive (pCDH p16-T2A-p21), expression of cell cycle inhibitors p16 and p21
proteins. We found that Fas expression has increased in the drug-induced senescent
cells which is in agreement with recently published data (Crescenzi et al., 2011). These
cells were also sensitized to FasL-induced apoptosis. Similarly, these senescent cells
were sensitized to campthotecin and mito-VES triggered apoptosis. In contrast, DR4
expression and sensitivity to TRAIL dropped in the senescent cells.
References
Hayflick, L. and Moorhead, P.S. (1961) The serial cultivation of human diploid cell strains.
Exp Cell Res, 25, 585-621.
Mirzayans, R., Scott, A., Cameron, M. (2005) Induction of accelerated senescence by
gamma radiation in human solid tumor-derived cell lines expressing wild-type TP53.
Radiat Res, 163, 53-62.
Bartek, J., Bartkova, J., Lukas, J. (2007) DNA damage signalling guards against activated
oncogenes and tumour progression. Oncogene, 26, 7773-7779.
Crescenzi, E., Pacifico, F., Lavorgna, A. et al. (2011) NF-κB-dependent cytokine secretion
controls Fas expression on chemotherapy-induced premature senescent tumor cells.
Oncogene, 30, 2707-2717.
138 Analytical Cytometry VII