title: Fas and c-kit are involved in the control of hair follicle melanocyte apoptosis and migration in chemotherapy-induced hair loss.
abstract: Chemotherapy alters the structure and function of hair follicle melanocytes. Molecular mechanisms controlling melanocyte responses during chemotherapy-induced hair loss, however, remain largely unknown. Using immunohistology and multicolor confocal microscopy, we show here that cyclophosphamide administration to C57BL/6 mice alters the activity and fate of hair follicle melanocytes. After 24-48 h, hair bulb melanocytes expressing Fas undergo apoptosis. The number of apoptotic follicular melanocytes is significantly reduced (p<0.01) in cyclophosphamide-treated Fas knockout mice compared to wild-type controls, suggesting that Fas signaling contributes to chemotherapy-induced melanocyte death. After 3-5 d, surviving hair bulb melanocytes express c-kit receptor, proliferate, and appear to migrate up the outer root sheath. Tyrosinase-positive and melanogenically active cells then appear in the epidermis. By Western blotting and immunohistochemistry, expression levels of the c-kit ligand, stem cell factor, in skin and epidermis are strongly increased after cyclophosphamide treatment. Cyclophosphamide-induced migration of the hair follicle melanocytes into epidermis is completely abrogated by administration of c-kit neutralizing antibody. These data suggest that chemotherapy induces a complex response in the hair follicle melanocytes, which includes apoptosis, proliferation, and migration. Pharmacologic manipulation of Fas and c-kit signaling pathways might be useful for the correction of skin hyperpigmentation as a side-effect of chemotherapy.
authors.affiliation: Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Andrei A
authors.initials: AA
authors.lastname: Sharov
authors.forename: Guang-Zhi
authors.initials: GZ
authors.lastname: Li
authors.forename: Tatyana N
authors.initials: TN
authors.lastname: Palkina
authors.forename: Tatyana Y
authors.initials: TY
authors.lastname: Sharova
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Gilchrest
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Botchkarev
mesh_terms: D000505:Alopecia / Q000139:chemically induced* / Q000473:pathology; D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D003520:Cyclophosphamide / Q000633:toxicity*; D005260:Female; D018859:Hair Follicle / Q000187:drug effects* / Q000473:pathology; D008544:Melanocytes / Q000187:drug effects* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D019009:Proto-Oncogene Proteins c-kit / Q000502:physiology*; D019014:fas Receptor / Q000502:physiology*
chemical_list: D000970:Antineoplastic Agents; D019014:fas Receptor; D003520:Cyclophosphamide; D019009:Proto-Oncogene Proteins c-kit