Ki-ras activation in vitro affects GI and G2M cell-cycle transit times and apoptosis

Roberto Orecchia, Edmondo Infusini, Andrea Sciutto, Anna Rapallo, Angela Di Vinci, Stefano Nigro, Elio Geido, Walter Giaretti

Research output: Contribution to journalArticlepeer-review


Mutant ras genes occur frequently in human neoplasia and, in particular, in pancreatic, colorectal, and lung adenocarcinomas. Recent evidence suggests that G→T and G→C transversions of the Ki-ras gene in codon 12 may lead to biological effects in vitro and in vivo that may be associated with an abnormal cell cycle and increased tumour aggressiveness. The role of Ki-ras activation (a G→C transversion in codon 12, arginine for glycine) in the cell cycle and apoptosis was investigated using control and permanently transfected NIH3T3 mouse fibroblasts. Flow cytometry was used to evaluate the GI-, S- and G2M-phase transit times, the potential doubling time, the growth fraction, and the cell loss factor during asynchronous exponential growth. Apoptosis was induced in both cell lines by absence of growth factors for an extended period of time (72 h) and quantitatively evaluated using the TUNEL method coupled with flow cytometry. It was found that codon 12 G→C Ki-ras transfected cells compared with controls, had a significant prolongation of G1 by about 50%, a reduction of the G2M transit time by 30%, and a decrease of the cell loss factor by about 90%. Apoptotic cells were about 10% in control and less than 0.5% in Ki-ras transfected cells after 72 h starvation- confluency. These data suggest that codon 12 G→C Ki-ras activation in mouse NIH3T3 fibroblasts is associated with deregulation of checkpoint controls in the G1 and G2M phases of the cell cycle and inhibition of apoptosis. It appears plausible that these cell mechanisms are related to a proliferative advantage and that they may also be important in the progression of human rumours characterized by specific Ki-ras mutations. Copyright (C) 2000 John Wiley and Sons, Ltd.

Original languageEnglish
Pages (from-to)423-429
Number of pages7
JournalJournal of Pathology
Issue number4
Publication statusPublished - Mar 2000


  • Apoptosis
  • Cell cycle
  • Ki-ras activation
  • Oncogenic signal
  • Proliferative advantage
  • Signal transduction
  • Tumour progression

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


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