Gene expression profile in Shh-expressing cells of hair follicles in mouse during CIA

Chemotherapy-induced alopecia (CIA) is a major unsolved adverse effect in clinical oncology. In previous studies, we proved the Sonic hedgehog(Shh) signaling pathway is a major target of cyclophosphamide (CYP). However, how CYP suppresses Shh gene remains unknown. In this study, we isolated Shh-expressing cells in hair follicles of Shh-GFP+/- mice treated with CYP and tested the effect of CYP on these cells. The result showed that Shh-expressing cells decreased significantly post-CYP treatment. RNA sequencing data showed that compared with the control group, 536 and 2,439 genes expressed differentially at 12hrs and 24hrs respectively post-CYP treatment. KEGG enrichment analysis revealed the p53 and the apoptosis signaling pathway were significantly enriched at 12hrs and 24hrs after CYP injection. The immunofluorescence staining of active Caspase 3 confirmed the apoptosis of Shh-expressing cells at 12 hours post-CYP treatment. GSEA analysis, ChIP assay, and AG-490 rescue assay revealed the IFN/JAK/STAT1 signaling pathway participated in regulating Shh during CIA. The results of this study demonstrated the decrease of Shh during CIA not only because of the loss of Shh-expressing cells but also because of the down expression of Shh in Shh-expressing cells. Moreover, this study also proved that apoptosis is the main reason for the loss of Shh-expressing cells, while the IFN/JAK/STAT1 signaling pathway may play an important role in the downregulation of Shh.