Poly(ADP-ribosyl)ation is implicated in the G0-G1 transition of resting cells.

Poly(ADP-ribosyl)ation, catalysed by a family of poly(ADP-ribose) polymerases (PARPs), plays an important role in a large variety of physiological processes, including cell proliferation, but its role in cell cycle progression is not yet completely defined. As reported here, the examination of early times following serum stimulation of quiescent fibroblasts suggests that poly(ADP-ribosyl)ation is necessary for the transition from the G0 phase to the G1 phase. We show that PARP activity is involved in this step through the regulation of immediate-early response genes, such as c-Fos and c-Myc. This is supported by the finding that exogenous Myc expression substantially restores cell cycle reactivation in the absence of polymer synthesis. Furthermore, using RNA interference, we show that PARP-1 is the PARP family member playing the most prominent role in the upregulation of c-Fos and c-Myc during G0-G1 transition. We report that even in lectin-stimulated peripheral blood mononucleated cells, the inhibition of PARP activity interferes with the upregulation of immediate-early genes and delays the induction of proliferation, suggesting a general role for PARP-1 in linking growth factor signaling with cell cycle entry.

[The value of extemporaneous study of the surgical margins of cancers of the upper aero-digestive tract. Apropos of 129 cases of oral and oropharyngeal tumors]. / Intérêt de l'étude extemporanée des limites d'exérèse dans les cancers des voies aéro-digestives supérieures (V.A.D.S.). A propos de 129 cas de tumeurs buccales et oro-pharyngées.

129 patients, who had oral cavity or oropharyngeal carcinoma underwent excision with intraoperative histopathologic examination. Thanks to this method, the number of satisfying resections has increased from 25% to 75%. Whatever the quality of the surgical excision may be, postoperative radiotherapy improves the prognosis.