Figure 3

PML immunofluorescence combined with Tel-FISH in U2OS, CM and QGP cell lines.
U2OS cell line represents a universal positive control for ALT mechanism. CM cell line, a TERTp wild-type cell line, presented a high co-localization of telomeric DNA with PML exhibiting an ALT positive phenotype. QGP1, the TERTp mutated cell line does not present frequent co-localization of telomeric DNA with being ALT negative. These findings recapitulate the observations in our series of PETs.