Involvement of Rel/Nuclear Factor-κB Transcription Factors in Keratinocyte Senescence

After a finite doubling number, normal cells become senescent, i.e. nonproliferating and apoptosis resistant. Because Rel/nuclear factor (NF)-κB transcription factors regulate both proliferation and apoptosis, we have investigated their involvement in senescence. cRel overexpression in young normal keratinocytes results in premature senescence, as defined by proliferation blockage, apoptosis resistance, enlargement, and appearance of senescence-associated β-galactosidase (SA-β-Gal) activity. Normal senescent keratinocytes display a greater endogenous Rel/NF-κB DNA binding activity than young cells; inhibiting this activity in presenescent cells decreases the number of cells expressing the SA-β-Gal marker. Normal senescent keratinocytes and cRel-induced premature senescent keratinocytes overexpressed manganese superoxide dismutase (MnSOD), a redox enzyme encoded by a Rel/NF-κB target gene. MnSOD transforms the toxic O2.- into H2O2, whereas catalase and glutathione peroxidase convert H2O2 into H2O. Neither catalase nor glutathione peroxidase is up-regulated during cRel-induced premature senescence or during normal senescence, suggesting that H 2O2 accumulates. Quenching H2O2 by catalase delays the occurrence of both normal and premature cRel-induced senescence. Conversely, adding a nontoxic dose of H2O2 to the culture medium of young normal keratinocytes induces a premature senescence-like state. All these results indicate that Rel/NF-κB factors could take part in the occurrence of senescence by generating an oxidative stress via the induction of MnSOD.

Incidence of febrile neutropenia and neutropenic infections in elderly patients receiving anthracycline-based chemotherapy for breast cancer without primary prophylaxis with colony-stimulating factors

There is concern about the potential increase of hematological toxicity in elderly patients treated with chemotherapy. Recently, primary prophylaxis with colony-stimulating factors (CSFs) was proposed for elderly patients receiving moderately toxic chemotherapy. However, evidence for the benefits of this primary prophylaxis for elderly breast cancer patients is currently lacking. We retrospectively analyzed the incidence of febrile neutropenia (FN) and neutropenic infections in elderly breast cancer patients receiving anthracycline-based chemotherapy without primary prophylaxis with colony-stimulating factors. In addition, we assessed the direct costs of hospitalization for these complications. Febrile neutropenia or neutropenic infection occurred in 13% of the 46 patients. Further studies are needed to adequately evaluate the risk of neutropenic complications (NC) in elderly patients receiving standard-dose chemotherapy for breast cancer and the potential benefits of primary prophylaxis with colony-stimulating factors. © 2004 Elsevier Ireland Ltd. All rights reserved.