Expression of α1-Adrenoceptor Subtype mRNA as a Predictor of the Efficacy of Subtype Selective α1-Adrenoceptor Antagonists in the Management of Benign Prostatic Hyperplasia

PurposeWe examined the correlation between the expression of α1-adrenoceptor subtype mRNA in the prostate and the clinical efficacy of subtype selective α1-adrenoceptor antagonists. We discuss the possibility of individualizing drug therapy in patients with benign prostatic hyperplasia.Materials and MethodsA total of 33 patients randomized to the tamsulosin group and 28 randomized to the naftopidil group were enrolled in this study. Each group of patients was administered 0.2 mg tamsulosin hydrochloride or 50 mg naftopidil daily for 12 weeks. Four prostate needle biopsy specimens were obtained from the transition zone to examine the expression of α-adrenoceptor subtypes. Specimens were stored at –80C until used for TaqMan® quantitative reverse transcriptase-polymerase chain reaction, which was performed after 12 weeks of treatment.ResultsBased on the results of quantitative reverse transcriptase-polymerase chain reaction the tamsulosin and naftopidil groups were grouped into α1a-adrenoceptor dominant (22 and 12 patients) and α1d-adrenoceptor dominant (11 and 16, respectively) subgroups. The efficacy of tamsulosin hydrochloride and naftopidil differed depending on the dominant expression of the α1-adrenoceptor subtype in the prostate. Tamsulosin hydrochloride was more effective in patients with dominant expression of the α1a-adrenoceptor subtype, whereas naftopidil was more effective in those with dominant expression of the α1d-adrenoceptor subtype.ConclusionsThe expression level of α1-adrenoceptor subtype mRNA in the prostate could be a predictor of the efficacy of subtype selective α1-adrenoceptor antagonists in patients with benign prostatic hyperplasia. This result implies that genetic differences are responsible for the diverse responses to these drugs.