v-Src Causes Chromosome Bridges in a Caffeine-Sensitive Manner by Generating DNA Damage

Abstract

An increase in Src activity is commonly observed in epithelial cancers. Aberrant activation of the kinase activity is associated with malignant progression. However, the mechanisms that underlie the Src-induced malignant progression of cancer are not completely understood. We show here that v-Src, an oncogene that was first identified from a Rous sarcoma virus and a mutant variant of c-Src, leads to an increase in the number of anaphase and telophase cells having chromosome bridges. v-Src increases the number of γH2AX foci, and this increase is inhibited by treatment with PP2, a Src kinase inhibitor. v-Src induces the phosphorylation of KAP1 at Ser824, Chk2 at Thr68, and Chk1 at Ser345, suggesting the activation of the ATM/ATR pathway. Caffeine decreases the number of cells having chromosome bridges at a concentration incapable of inhibiting Chk1 phosphorylation at Ser345. These results suggest that v-Src induces chromosome bridges via generation of DNA damage and the subsequent DNA damage response, possibly by homologous recombination. A chromosome bridge gives rise to the accumulation of DNA damage directly through chromosome breakage and indirectly through cytokinesis failure-induced multinucleation. We propose that v-Src-induced chromosome bridge formation is one of the causes of the v-Src-induced malignant progression of cancer cells.

The tyrosine kinase v-Src causes mitotic slippage by phosphorylating an inhibitory tyrosine residue of Cdk1

“…v-Src expression was induced by a higher concentration of Dox used in this study than in our previous one (6). In our previous studies, we had used lower concentrations of Dox to induce v-Src expression at lower levels in v-Srcinducible cell clones (6,7,22,25). This experimental condition allowed us to observe the effects of v-Src without detachment of cells.…”

“…Tetraploid cells transiently form multipolar spindle intermediates and can generate merotelic attachments (23), leading to chromosome instability through lagging chromosome formation (24). Furthermore, v-Src induces chromosome bridge formation through the caffeine-sensitive DNA damage response (25). This can lead to further cytokinesis failure by attenuating the abscission checkpoint through Aurora B delocalization from the spindle midbody (7).…”

Lipopolysaccharide‐induced DNA damage response activates nuclear factor κB signalling pathway via GATA4 in dental pulp cells

“…The 2# GATA4 siRNA showed better inhibitory efficiency. To investigate the role of DSBs in LPS-induced activation of NF-jB in hDPCs, caffeine was used for inhibiting DDR by inhibiting the checkpoint kinases, ATM and ATR (Ikeuchi et al 2016). (c) mRNA levels of IL-1b, IL-6 and TNF-a showed an obvious downregulation in the Si group in comparison with the Nc group.…”

“…However, the mechanisms underlying induction of DNA damage and inflammatory response in hDPCs have remained unknown. To investigate the role of DSBs in LPS-induced activation of NF-jB in hDPCs, caffeine was used for inhibiting DDR by inhibiting the checkpoint kinases, ATM and ATR (Ikeuchi et al 2016). When caffeine inhibits the ATM/ATR pathway of DDR, the expression of c-H2A.X in hDPCs decreases.…”

“…Therefore, the present study aims to elucidate the role of GATA4 in the inflammatory response induced by DSBs in hDPCs. Caffeine (an inhibitor of DNA damage) was selected to change processes of DDR (Ginet et al 2014, Guo et al 2014, Ikeuchi et al 2016. Moreover, GATA4 small interfering RNA (siRNA) technology was utilized for elucidating the role of GATA4 in LPS-stimulated hDPCs.…”