HISTAMINE H4 RECEPTOR AS A NOVEL THERAPEUTIC TARGET FOR THE TREATMENT OF LEYDIG CELL TUMORS IN PREPUBERTAL BOYS

PIGNATARO OMAR P; MARCOS, ALEJANDRA; VARELA, MARÍA LUISA; MONDILLO CAROLINA; BELGOROSKY, ALICIA; BESIO MORENO MARCOS; ABIUSO, ADRIANA MARÍA BELÉN; BERENSZTEIN, ESPERANZA; RIVAROLA, MARCO AURELIO; HARO DURAND, LUIS

Miami

Congreso; XXIV North American Testis Workshop; 2017

American Society of Andrology

HISTAMINE H4 RECEPTOR AS A NOVEL THERAPEUTIC TARGET FOR THE TREATMENT OF LEYDIG CELL TUMORS IN PREPUBERTAL BOYS Adriana M. B. Abiuso1, María Luisa Varela2, Luis Haro Durand3, Marcos Besio Moreno1, Alejandra Marcos1, Marco A. Rivarola4, Alicia Belgorosky4, Omar P. Pignataro1, Esperanza Berensztein4 and Carolina Mondillo1 1Lab. de Endocrinología Molecular y Transducción de Señales − IBYME−CONICET, Buenos Aires, Argentina; 2Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Laboratorio de Ecotoxicología Acuática. CONICET−Universidad de Buenos Aires. Instituto de Biodiversidad y Biología Experimental−CONICET (IBBEA). Buenos Aires, Argentina.; 3Lab. de Patología y Farmacología Molecular − IBYME − CONICET, Buenos Aires, Argentina; 4Servicio de Endocrinología − Hospital de Pediatría Juan P. Garrahan, Buenos Aires, Argentina Introduction: Leydig cell tumors (LCTs) are rare steroid−secreting tumors of the testicular stroma, with apparent increased incidence. Symptoms include feminization or virilization in prepubertal boys, and loss of libido, erectile dysfunction, infertility and/or gynecomastia in adults. Although the etiology of LCTs is unknown, multiple studies indicate that overexpression of aromatase (CYP19), as well as excessive estrogen (E2) and IGF−1 production, play a role in Leydig cell tumorigenesis. LCTs are usually benign; however, the malignant phenotype responds poorly to chemo/radiotherapy, highlighting the need to identify novel therapeutic targets for treatment. HRH4, the newest member of the HA receptor family, is considered a promising drug target for allergy, inflammation, autoimmune disorders, and cancer. Objetive: To investigate the potential role of HRH4 as a therapeutic target for LCTs. Methods: Most of the experiments described herein were perfomed in R2C rat Leydig tumor cells, a well−documented in vitro model for Leydigioma. The expression of HRH4, StAR and CYP19 was evaluated by qPCR and Western Blot. P4 and E2 levels were determined by radioimmunoassay, and cell proliferation was assessed as a function of 3H−Thymidine incorporation. The angiogenic capacity of R2C cells and the effect of HRH4 agonist treatment on this capacity were evaluated in vitro and in vivo, employing human umbilical vein endothelial cells and by means of the quail chorioallantoic membrane assay, respectively. Also, HRH4 immunoexpression was evaluated in 2 human LCTs (3,92 and 6,0 years old) versus 9 normal human testis samples (NHTS) belonging to four different age groups: neonatal, n=2; infantile, n=1; juvenile, n=3 and pubertal, n=3. Results: E2 and IGF−1 negatively regulated HRH4 mRNA and protein levels in R2C cells. In agreement, HRH4 expression was weak in LCTs, whereas we observed moderate to strong HRH4 staining, confined to the interstitium, in all the NHTS analyzed. No HRH4 was detected in seminiferous tubules or germ cells. Treament of R2C cells with two specific HRH4 agonists inhibited StAR expression, P4 and E2 synthesis, CYP19 expression, and cell proliferation. Finally, selective HRH4 activation negatively affected the angiogenic capacity of R2C cells. Conclusion: Our results point to HRH4 as a potential therapeutic target for LCTs in prepubertal boys. Further studies are needed to determine if this conclusion can be extrapolated to adult patients.