OBJECTIVE: Dopamine plays a key role in the proliferation regulation of the smooth muscle cells. The purpose of this study was to observe the degree of expression of dopamine D1 and D2 receptors and dopamine transporter (DAT) and to evaluate the influence of methylation about control of expression of DAT in uterine leiomyoma and normal myometrial tissue. METHODS: In 20 patients who underwent hysterectomy due to uterine leiomyoma, normal myometrial and leiomyoma specimens were obtained. The expression of dopamine D1 and D2 receptors and DAT was demonstrated by using RT-PCR and immunohistochemistry in each normal myometrium and leiomyoma. Analysis of the DNA methylation status of DAT was conducted using HpaII digestion and the methylation-sensitive PCR. RESULTS: The mRNA level of dopamine D1 receptor was relatively higher in normal myometrium than D2 receptor and it was also unchanged in leiomyomas. However, the mRNA levels of dopamine D2 receptor and DAT in leiomyomas were much higher than normal myometrium. Consistent with elevated mRNA levels, high levels of dopamine receptors protein expression were detected by immunohistochemistry in leiomyomas. The degree of methylation at CpG sites of the area intron 1 of DAT (genomic position, +377 - +888) was decreased in leiomyomas. CONCLUSION: These results suggest that overexpressed dopamine D2 receptor and DAT would be associated with proliferation of human uterine leiomyomas and the methylation status of the CpG island of DAT determines its expression.
Animals ; CpG Islands ; Digestion ; DNA Methylation ; Dopamine Plasma Membrane Transport Proteins* ; Dopamine* ; Female ; Humans ; Hysterectomy ; Immunohistochemistry ; Introns ; Leiomyoma* ; Methylation ; Mice ; Myocytes, Smooth Muscle ; Myometrium ; Polymerase Chain Reaction ; Receptors, Dopamine D1 ; Receptors, Dopamine D2 ; Receptors, Dopamine* ; RNA, Messenger