Distinct signalling pathways for mutated KIT(V560G) and KIT(D816V) in mastocytosis

Abstract

BACKGROUND: The activating mutations KIT(V560G) and KIT(D816V) are associated with mastocytosis. Thus, identifying and inhibiting the signalling pathways associated with mutated KIT gene offers a potentially important strategy for the treatment of mastocytosis. AIM: To correlate KIT mutations with specific signalling pathways in human mast-cell lines using pathway inhibitors. METHODS: Human mast-cell (HMC) lines expressing KIT(V560G) (the cell line HMC-1) and KIT(V560G and D816V) (HMC-1.2) were treated with specific signalling pathway inhibitors for 1-5 days, and the inhibitory effects on growth were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell-proliferation assay, western blotting and flow cytometry. RESULTS: Growth inhibitory assays and western blot analyses showed that the Janus kinase 3/signal transducer and activator of transcription (JAK3/STAT) pathway is the preferential signalling pathway for KIT(V560G), whereas the mechanistic target of rapamycin complex 1/4E-binding protein 1 (mTORC1/4E-BP1) pathway is preferentially linked to KIT(D816V). Inhibition of these critical signalling pathways results in programmed cell death. CONCLUSIONS: KIT(V560G) and KIT(D816V) use different signalling pathways that promote mast-cell growth. Inhibitors of these specific pathways might be effective in treating mastocytosis.