Everolimus-induced human keratinocytes toxicity is mediated by STAT3 inhibition

Abstract

BackgroundMammalian target of rapamycin (mTOR) inhibitors are associated with dermatological adverse events. The chief aim of this study was to examine the relation between the signal transducer and activator of transcription 3 (STAT3) protein and the dermatological adverse events associated with the mTOR inhibitor everolimus.MethodsWe evaluated the effects of STAT3 activity and related signal transduction activities on everolimus-induced cell growth inhibition in the human keratinocyte HaCaT cell line via a WST-8 assay, and on signal transduction mechanisms involved in everolimus treatments via a western blot analysis. Apoptosis was evaluated using an imaging cytometric assay.ResultsThe cell growth inhibitory effects of everolimus were enhanced by stattic or STA-21, which are selective inhibitors of STAT3, treatment in HaCaT cells, although such effects were not observed in Caki-1 and HepG2 cells. Phosphorylation at tyrosine 705 of STAT3 was decreased by treatment with everolimus in a dose-dependent manner in HaCaT cells; in contrast, phosphorylation at serine 727 was not decreased by everolimus, but slightly increased. Furthermore, we found that pretreatment of p38 MAPK inhibitor and transfection with constitutively active form of STAT3 in HaCaT cells resisted the cytostatic activity of everolimus.ConclusionsThese findings suggest that STAT3 activity may be a biomarker of everolimus-induced dermatological toxicity.

Bullous pemphigoid induced by m‐TOR inhibitors in renal transplant recipients

“…Inhibition of mTOR kinases affects signalling pathways regulating cell cycle and growth, angiogenesis and tissue repair . The skin is an unwanted target experiencing several side‐effects, and experimental data have postulated a direct mTOR activity on human keratinocytes altering the downstream signalling pathway . Influences on intracellular functions, such as motility and adhesion or desmosomal junctions assemblage might be relevant in the induction of the bullous autoimmune disease.…”

“…[1][2][3][4] The skin is an unwanted target experiencing several side-effects, and experimental data have postulated a direct mTOR activity on human keratinocytes altering the downstream signalling pathway. 13 Influences on intracellular functions, such as motility and adhesion or desmosomal junctions assemblage might be relevant in the induction of the bullous autoimmune disease. Another case of BP in a kidney-transplanted patient has been reported in Italy, in which everolimus was suspected and withdrawn, but at the moment of the publication the patient was still under corticosteroid therapy, and rechallenge was not performed.…”

s-HBEGF/SIRT1 circuit-dictated crosstalk between vascular endothelial cells and keratinocytes mediates sorafenib-induced hand–foot skin reaction that can be reversed by nicotinamide

“…The vascular endothelial cell-keratinocyte axis is a novel insight into the mechanism underlying drug-induced cutaneous diseases, given that a majority of previous studies have only identified the keratinocyte as the primary regulator of drug-specific dermatological toxicities. [20][21][22] In fact, due to the complex internal structures and functions of organisms, drugs may not always directly influence their effector cells and immediately give rise to pathological processes. Intricate cases of crosstalk were reported to occur among different types of cells at the onset of various drug toxicities, such as doxorubicin-induced cardiotoxicity and bleomycin-induced pulmonary fibrosis.…”

“…Hyper-keratosis, including hyper-proliferation and hyper-differentiation, arises from the epidermal dyshomeostasis in keratinocytes. [16][17][18][19] Given that most cutaneous toxicities induced by drugs (e.g., everolimus, adriamycin liposome, and capecitabine) are caused by cellular processes targeting keratinocytes, [20][21][22] we initially sought to test the direct effect of sorafenib on keratinocytes by employing human primary keratinocytes and HaCaT cells, the immortalized human keratinocytes which largely retained the differentiation capacity of normal epidermal cells. 24 We examined the states of proliferation and differentiation in keratinocytes, with keratin 5 (KRT5) and keratin 14 (KRT14) applied as proliferation markers, and keratin 1 (KRT1), keratin 10 (KRT10), loricrin (LORICRIN) and involucrin (IVL) characterizing differentiation.…”

“…[12][13][14][15] Hyper-keratosis, defined as stratum corneum thickening, generally results from the abnormality in epidermal homeostasis of keratinocytes, including hyperproliferation and hyper-differentiation. [16][17][18][19] Since numerous studies have uncovered that most drug-induced cutaneous toxicities are the aftereffects of pathways directly affecting keratinocytes, [20][21][22] keratinocyte dysfunction has thus been largely speculated as the main cause of sorafenib-induced HFSR. However, intervention strategies based on such concept are proven ineffective.…”