Stewart, Sheila A.

ABSTRACT Chemotherapy-induced peripheral neuropathy (CIPN) is a common, debilitating complication of cancer therapy. Although axonal degeneration defines CIPN, the initiating cellular events remain unknown. Here, we show that CIPN is initiated by senescent peripheral fibroblasts rather than by the neuron itself. Across the mechanistically distinct chemotherapeutic agents paclitaxel and cisplatin, chemotherapy-induced senescence is unexpectedly restricted to peripheral fibroblasts rather than neurons and acts upstream of neuronal SARM1 activation. Genetic or pharmacological ablation of senescent fibroblasts prevents neuropathy and reverses established disease, demonstrating that these cells are required for both disease initiation and maintenance. Mechanistically, senescent fibroblasts drive neuropathic injury through an MK2-dependent senescence-associated secretory phenotype (SASP), and genetic or pharmacological inhibition of MK2 suppresses the SASP, preserves peripheral innervation and restores sensory function. Together, these findings redefine the cellular origin of CIPN and identify MK2-dependent fibroblast senescence as a therapeutic target.

Abstract Chemotherapy is important for cancer treatment, however, toxicities limit its use. While great strides have been made to ameliorate the acute toxicities induced by chemotherapy, long-term comorbidities including bone loss remain a significant problem. Chemotherapy-driven estrogen loss is postulated to drive bone loss, but significant data suggests the existence of an estrogen-independent mechanism of bone loss. Using clinically relevant mouse models, we showed that senescence and its senescence-associated secretory phenotype (SASP) contribute to chemotherapy-induced bone loss that can be rescued by depleting senescent cells. Chemotherapy-induced SASP could be limited by targeting the p38MAPK-MK2 pathway, which resulted in preservation of bone integrity in chemotherapy-treated mice. These results transform our understanding of chemotherapy-induced bone loss by identifying senescent cells as major drivers of bone loss and the p38MAPK–MK2 axis as a putative therapeutic target that can preserve bone and improve a cancer survivor's quality of life. Significance: Senescence drives chemotherapy-induced bone loss that is rescued by p38MAPK or MK2 inhibitors. These findings may lead to treatments for therapy-induced bone loss, significantly increasing quality of life for cancer survivors.