J Am Acad Dermatol. 2003 Aug;49(2):229-33.
The expression of insulin-like growth factor 1 in follicular dermal papillae correlates with therapeutic efficacy of finasteride in androgenetic alopecia.
Tang L1, Bernardo O, Bolduc C, Lui H, Madani S, Shapiro J.
It is generally believed that dihydrotestosterone is one of the pivotal mediators of hair loss in androgenetic alopecia (AGA). Finasteride, which blocks the conversion of testosterone to dihydrotestosterone, has now become an integral part of the current treatment approaches for male AGA. Several lines of evidence support the notion that dermal papilla (DP) cells represent the androgen target within the hair follicle. The specific molecular regulators modulated by androgens within hair follicles in the balding scalp are unknown.
The purpose of this study was to identify and quantify changes in expression of specific molecular hair growth regulators in DP of men with AGA treated with finasteride and correlate these findings to clinical efficacy.
Biopsy specimens were collected from 9 male patients from both the balding area and nonbalding occipital area before and after 4 months of finasteride therapy. DP were microdissected and total RNA was extracted from an equal number of DP from each biopsy specimen. The expression of various cytokines, including insulin-like growth factor (IGF)-1, was determined by reverse transcription polymerase chain reaction. The signals were detected by autoradiography. All 9 patients were given finasteride for 1 year and evaluated for efficacy at month 12. Efficacy was graded on a 7-point scale on the basis of comparison with initial baseline photography.
IGF-1 was up-regulated by finasteride treatment in 4 of 9 patients. Among the patients with increased IGF-1 expression, 3 of them showed moderate clinical improvement after 12 months of treatment and another patient remained unchanged. In contrast, 3 patients with decreased IGF-1 expression in the balding scalp showed clinical worsening after 12 months. The other 2 patients without noticeable change in IGF-1 expression showed either slight improvement or no change in their hair condition.
In a small uncontrolled study of 9 patients with AGA, an increased expression of IGF-1 messenger RNA levels in the DP was associated with patient response to finasteride.