Oxaliplatin-Induced Senescence in Colorectal Cancer Cells Depends on p14(ARF)-Mediated Sustained p53 Activation

SIMPLE SUMMARY: Chemotherapy can lead to cellular senescence in tumor cells. Here we demonstrate that oxaliplatin induces senescence in p53-proficient colorectal cancer (CRC) cells and leads to the G2-phase arrest in all lines studied (HCT116(p53+/+,) HCT116(p53−/−), LoVo, SW48, and SW480). At early times the p53-competent lines activate p53 and p21(CIP1), however, at later times, only LoVo cells showed sustained p53/p21(CIP1) activation, accompanied by a strong induction of senescence and senescence-associated secretory phenotype (SASP) factors. Opposite to LoVo, the p53/p21(CIP1) response and senescence induction is much weaker in the other p53-proficient cells, due to p14(ARF) deficiency. LoVo cells express p14(ARF) protein and siRNA-mediated knockdown of p14(ARF) significantly reduces sustained p53/p21(CIP1) activation and senescence. Vice versa, ectopic expression of p14(ARF) enhances oxaliplatin-induced senescence in SW48 and SW480 cells. Our data show that oxaliplatin-induced senescence in CRC cells depends on p53 proficiency; however, a significant induction can only be observed upon p14(ARF)-mediated p53 stabilization. ABSTRACT: Senescence is an important consequence of cytostatic drug-based tumor therapy. Here we analyzed to which degree the anticancer drug oxaliplatin induces cell death, cell cycle arrest, and senescence in colorectal cancer (CRC) cells and elucidated the role of p53. Oxaliplatin treatment resulted in the G2-phase arrest in all CRC lines tested (HCT116(p53+/+), HCT116(p53−/−), LoVo, SW48 and SW480). Immunoblot analysis showed that within the p53-competent lines p53 and p21(CIP1) are activated at early times upon oxaliplatin treatment. However, at later times, only LoVo cells showed sustained activation of the p53/p21(CIP1) pathway, accompanied by a strong induction of senescence as measured by senescence-associated β-Gal staining and induction of senescence-associated secretory phenotype (SASP) factors. Opposite to LoVo, the p53/p21(CIP1) response and senescence induction was much weaker in the p53-proficient SW48 and SW480 cells, which was due to deficiency for p14(ARF). Thus, among lines studied only LoVo express p14(ARF) protein and siRNA-mediated knockdown of p14(ARF) significantly reduced sustained p53/p21(CIP1) activation and senescence. Vice versa, ectopic p14(ARF) expression enhanced oxaliplatin-induced senescence in SW48 and SW480 cells. Our data show that oxaliplatin-induced senescence in CRC cells is dependent on p53 proficiency; however, a significant induction can only be observed upon p14(ARF)-mediated p53 stabilization.