Introduction: p53 protein is a critical regulator of cell cycle and apoptosis. Many stimuli change its expression and modify its functions. The aim of our work was to determine stability and chosen posttranslational modification of p53 protein during the treatment of lung cancer.
Material and methods: We investigated levels of poly-ADP-ribose- a marker of cellular DNA damage, DNA ploidy, Ki-67 expression, wild type and mutated p53 protein expression and intensity of phosphorylation of chosen p53 serine sites: C-terminal Ser392, and N-terminal Ser15, and Ser20 in fiberoptic bronchoscopy biopsy samples taken from patients suffering from recurrent squamous cell lung cancer before and after radio/chemotherapy. Analysis was based on results obtained from 23 patients after surgery in I-IIIA clinical stage of the disease.
Results: Therapy lowered the number of G2/M cells, but increased S fraction cell population in about 50%. Therapy increased p53 expression and p53 phosphorylation at Ser392 and Ser20, and these changes correlated with poly-ADP-ribose levels and Ki-67 expression.
Conclusions: Our results indicate that apart from changes in p53 quantity, p53 posttranslational phosphorylation play a role in regulation of neoplastic cells proliferation in response to drugs.