KIP publications

Escape from mitotic catastrophe and generation of endopolyploid tumour cells (ETCs) represents a
potential survival strategy of tumour cells in response to genotoxic treatments. ETCs that resume the
mitotic cell cycle have reduced ploidy and are often resistant to these treatments. In search for a
mechanism for genome reduction, we previously observed that ETCs express meiotic proteins among
which REC8 (a meiotic cohesin component) is of particular interest, since it favours reductional cell
division in meiosis. In the present investigation, we induced endopolyploidy in p53-dysfunctional
human tumour cell lines (Namalwa, WI-L2-NS, HeLa) by gamma irradiation, and analysed the subcellular            localisation of REC8 in the resulting ETCs. We observed by RT-PCR and Western blot that REC8
is constitutively expressed in these tumour cells, along with SGOL1 and SGOL2, and that REC8
becomes modified after irradiation. REC8 localised to paired sister centromeres in ETCs, the former
co-segregating to opposite poles. Furthermore, REC8 localised to the centrosome of interphase ETCs
and to the astral poles in anaphase cells where it colocalised with the microtubule-associated protein
NuMA. Altogether, our observations indicate that radiation-induced ETCs express features of meiotic
cell divisions and that these may facilitate chromosome segregation and genome reduction.