RESUMO
BACKGROUND: Most childhood cancer survivors will develop ionizing radiation treatment-related health conditions that, in many instances, resemble age-associated pathologies. Treatment-induced premature senescence could be an underlying mechanism. FINDINGS: Here we wanted to know whether the expression of p16INK4a, a senescence/aging biomarker, is increased in skin biopsies of acute lymphoblastic leukemia survivors (ALL), previously exposed to chemotherapy and radiation therapy. Several years post-treatments, we found p16INK4a mRNA levels are 5.8 times higher in scalp skin biopsies (targeted by cranial irradiation therapy) compared to buttocks skin biopsies (n = 10, p = 0.01). CONCLUSIONS: These results demonstrate for the first time that premature senescence is induced in pediatric cancer survivors and that p16INK4a expression could be used as a potential biomarker in this population.
Assuntos
Senescência Celular , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Regulação Leucêmica da Expressão Gênica , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Adolescente , Adulto , Biomarcadores/metabolismo , Biomarcadores Tumorais/metabolismo , Feminino , Seguimentos , Humanos , Masculino , Projetos Piloto , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/radioterapia , Radiação Ionizante , Radioterapia/efeitos adversos , Couro Cabeludo/metabolismo , Pele/metabolismo , Resultado do Tratamento , Adulto JovemRESUMO
Exposure to IR has been shown to induce the formation of senescence markers, a phenotype that coincides with lifelong delayed repair and regeneration of irradiated tissues. We hypothesized that IR-induced senescence markers could persist long-term in vivo, possibly contributing to the permanent reduction in tissue functionality. Here, we show that mouse tissues exposed to a sublethal dose of IR display persistent (up to 45 weeks, the maximum time analyzed) DNA damage foci and increased p16(INK4a) expression, two hallmarks of cellular senescence and aging. BrdU-labeling experiments revealed that IR-induced damaged cells are preferentially eliminated, at least partially, in a tissue-dependent manner. Unexpectedly, the accumulation of damaged cells was found to occur independent from the DNA damage response modulator p53, and from an intact immune system, as their levels were similar in wild-type and Rag2(-/-) gammaC(-/-) mice, the latter being deficient in T, B, and NK cells. Together, our results provide compelling evidence that exposure to IR induces long-term expression of senescence markers in vivo, an effect that may contribute to the reduced tissue functionality observed in cancer survivors.
