Human Leiomyoma Express a Second Form of Gonadotropin-Releasing Hormone (GnRH 2) and Receptor (GnRHR 2)

Abstract

To determine the presence or absence of a second form of gonadotropin-releasing hormone (GnRH 2) and corresponding receptor (GnRHR 2) in human uterine myometrium and leiomyomata. High throughput genotyping of human leiomyoma and patient-matched myometrium, followed by confirmatory studies for both mRNA and protein expression of GnRH 2 and GnRHR 2. Differential expression was evaluated by paired Student’s t tests. Confidence intervals were calculated. Leiomyoma and adjacent myometrium was obtained following a hysterectomy for a symptomatic fibroid uterus from eight women enrolled into an IRB approved protocol. Microarray analysis was performed to screen for the genes of interest. Confirmation was performed by Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR). Real-Time RT-PCR quantified the relative gene expression of these genes in leiomyoma compared with patient matched myometrium. Confirmation of protein expression was performed by immunohistochemistry of GnRH 2 in both leiomyoma and myometrium. Microarray analysis demonstrated expression, which was confirmed by Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR). Real-Time RT-PCR demonstrated mean GnRH 2 fold difference in myometrium compared to fibroid was 0.99 (95% C.I. 0.47, 1.51), while the GnRHR 2 fold difference was 1.28 (95% C.I. 0.90, 1.66), see Table 1. Tabled 1 Immunohistochemistry confirmed the protein expression of GnRH 2 in both leiomyoma and myometrium. Figure 1 demonstrates the H&E stain of myometrium (A) and fibroid (C), immunohistochemistry staining with GnRH 2 of myometrium (B) and fibroid (D). A second form of GnRH, GnRH 2, and its corresponding receptor, GnRHR 2, exists in fibroid and myometrium. Our results support a hypothesis by which GnRH agonists could directly influence uterine fibroid regression separate from a mechanism involving estrogen and progesterone.