Expression of GHRH-R, a Potentially Targetable Biomarker, in Triple-negative Breast Cancer

The Potential Prognostic and Therapeutic Implications of Prolactin Receptor and Growth Hormone-releasing Hormone Receptor Expression in Uterine Leiomyosarcomas

The management of uterine leiomyosarcomas (uLMS) remains challenging. The rate of recurrence and metastasis is high, with 5-yr survival reaching only 40% to 50% in patients with tumor confined to the uterus (FIGO stage I or II). Prolactin receptor (PRLR) and growth hormone-releasing hormone receptor (GHRHR) have been implicated in the carcinogenesis of malignant tumors of the breast, endometrium, ovary, liver, and prostate. GHRHR antagonists inhibit in vitro growth of many human tumors and the expression of PRLR is associated with resistance to chemotherapy. The immunohistochemical expression of PRLR and GHRH in 24 primary and 2 recurrent uLMS was evaluated. Representative sections were stained with PRLR and GHRHR antibodies and immunoreactivity was calculated using H -score. The results were correlated with clinicopathologic data using Kaplan-Meier survival and multivariable Cox proportion hazard regression analyses. All tumors were positive for both markers with predominantly moderate to strong expression of PRLR (89%) and GHRHR (82%). Patients with tumors showing moderate to strong expression of PRLR were significantly less likely to achieve disease-free survival ( P =0.004) and significantly more likely to have a poor overall survival ( P =0.049). No significant difference in mean PRLR expression was found between tumors with higher mitotic counts (>20/10 hpf) and lower mitotic counts (20 or less/10 hpf). Furthermore, in 2 patients where the primary and recurrent tumors were tested, there was stronger expression of PRLR in the recurrence compared with the primary. This correlation was not found with GHRHR. Both PRLR and GHRHR may play a role in carcinogenesis in uLMS, as they do in other malignant neoplasms. To our knowledge, this study is the first evaluating the expression of these receptors in uLMS. Moderate or high expression of PRLR may serve as a prognostic marker associated with recurrences and increased mortality in uLMS patients.

Expression of Growth Hormone-Releasing Hormone and Its Receptor Splice Variants in Primary Human Endometrial Carcinomas: Novel Therapeutic Approaches

Antagonists of growth hormone-releasing hormone (GHRH) inhibit the growth of various tumors, including endometrial carcinomas (EC). However, tumoral receptors that mediate the antiproliferative effects of GHRH antagonists in human ECs have not been fully characterized. In this study, we investigated the expression of mRNA for GHRH and splice variants (SVs) of GHRH receptors (GHRH-R) in 39 human ECs and in 7 normal endometrial tissue samples using RT-PCR. Primers designed for the PCR amplification of mRNA for the full length GHRH-R and SVs were utilized. The PCR products were sequenced, and their specificity was confirmed. Nine ECs cancers (23%) expressed mRNA for SV1, three (7.7%) showed SV2 and eight (20.5%) revealed mRNA for SV4. The presence of SVs for GHRH-Rs could not be detected in any of the normal endometrial tissue specimens. The presence of specific, high affinity GHRH-Rs was also demonstrated in EC specimens using radioligand binding studies. Twenty-four of the investigated thirty-nine tumor samples (61.5%) and three of the seven corresponding normal endometrial tissues (42.9%) expressed mRNA for GHRH ligand. Our findings suggest the possible existence of an autocrine loop in EC based on GHRH and its tumoral SV receptors. The antiproliferative effects of GHRH antagonists on EC are likely to be exerted in part by the local SVs and GHRH system.