title: Outcome of treatment of human HeLa cervical cancer cells with roscovitine strongly depends on the dosage and cell cycle status prior to the treatment.
abstract: Exposure of asynchronously growing human HeLa cervical carcinoma cells to roscovitine (ROSC), a selective cyclin-dependent kinases (CDKs) inhibitor, arrests their progression at the transition between G(2)/M and/or induces apoptosis. The outcome depends on the ROSC concentration. At higher dose ROSC represses HPV-encoded E7 oncoprotein and initiates caspase-dependent apoptosis. Inhibition of the site-specific phosphorylation of survivin and Bad, occurring at high-dose ROSC treatment, precedes the onset of apoptosis and seems to be a prerequisite for cell death. Considering the fact that in HeLa cells the G(1)/S restriction checkpoint is abolished by E7, we addressed the question whether the inhibition of CDKs by pharmacological inhibitors in synchronized cells would be able to block the cell-cycle in G(1) phase. For this purpose, we attempted to synchronize cells by serum withdrawal or by blocking of the mitotic apparatus using nocodazole. Unlike human MCF-7 cells, HeLa cells do not undergo G(1) block after serum starvation, but respond with a slight increase of the ratio of G(1) population. Exposure of G(1)-enriched HeLa cells to ROSC after re-feeding does not block their cell-cycle progression at G(1)-phase, but increases the ratio of S- and G(2)-phase, thereby mimicking the effect on asynchronously growing cells. A quite different impact is observed after treatment of HeLa cells released from mitotic block. ROSC prevents their cell cycle progression and cells transiently accumulate in G(1)-phase. These results show that inhibition of CDKs by ROSC in cells lacking the G(1)/S restriction checkpoint has different outcomes depending on the cell-cycle status prior to the onset of treatment.
authors.affiliation: Cell Cycle Regulation Group, Department of Medicine I, Div. Institute of Cancer Research, Medical University of Vienna, Vienna, Austria. jozefa.gadek-wesierski@meduniwien.ac.at
authors.forename: Józefa
authors.initials: J
authors.lastname: Wesierska-Gadek
authors.forename: Andreea
authors.initials: A
authors.lastname: Borza
authors.forename: Eva
authors.initials: E
authors.lastname: Walzi
authors.forename: Vladimir
authors.initials: V
authors.lastname: Krystof
authors.forename: Margarita
authors.initials: M
authors.lastname: Maurer
authors.forename: Oxana
authors.initials: O
authors.lastname: Komina
authors.forename: Stefanie
authors.initials: S
authors.lastname: Wandl
mesh_terms: D002453:Cell Cycle; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D005260:Female; D016193:G1 Phase; D006367:HeLa Cells; D006801:Humans; D011687:Purines / Q000494:pharmacology*; D000077546:Roscovitine; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy* / Q000473:pathology
chemical_list: D016895:Culture Media, Serum-Free; D011687:Purines; D000077546:Roscovitine; D018844:Cyclin-Dependent Kinases