The role of icIL-1RA type 1 in oral keratinocyte senescence and the development of the senescence associated secretory phenotype
There is compelling evidence that senescent cells, through the senescence-associated secretory phenotype (SASP), can promote malignant transformation and invasion. IL-1 is a key mediator of this cytokine network, but the control of its activity in the senescence program has not been elucidated. IL-1 signalling is regulated by IL-1RA, which has four variants. Here, we show that expression of intracellular IL-1RA type 1 (icIL-1RA1), which competitively inhibits binding of IL-1 to its receptor, is progressively lost during oral carcinogenesis ex vivo and that the pattern of expression is associated with keratinocyte replicative fate in vitro. We demonstrate icIL-1RA1 is an important regulator of the SASP in mortal cells, as CRISPR-CAS9 mediated icIL-1RA1 knockdown in normal and mortal dysplastic oral keratinocytes is followed by increased IL-6 and IL-8 secretion, and rapid senescence following release from ROCK inhibition. Thus, we suggest that downregulation of icIL-1RA1 in early stages of the carcinogenesis process can enable the development of a premature and de-regulated SASP, creating a pro-inflammatory state in which cancer is more likely to arise.Competing Interest StatementThe authors have declared no competing interest.View Full Text