Androgens Modulate Bcl-2 Agonist of Cell Death (BAD) Expression and Function in Breast Cancer Cells

Androgen receptor (AR) expression in estrogen receptor-positive (ER+) breast cancer (BC) correlates with lower tumor grade and a better clinical outcome. Additionally, in normal mammary epithelium or ER+ BC preclinical models, androgens counteract basal/ER-dependent proliferation. Here, we report an additional mechanism, underlining the protective role exerted by AR. Specifically, the activation of intracellular AR upregulates the Bcl-2-family protein BAD, and TCGA database analyses show that in ER+ BC, BAD expression is associated with better disease-free survival. Ligand-activated AR influences its own and BAD cellular compartmentalization by enhancing levels in the nucleus, as well as in mitochondrial fractions. In both compartments, BAD exerts unconventional functions. In the nucleus, BAD and AR physically interact and, upon androgen stimulation, are recruited at the AP-1 and ARE sites within the cyclin D1 promoter region, contributing to explaining the anti-proliferative effect of androgens in BC cells. Androgens cause an enrichment in BAD and AR content in the mitochondria, correlated with a decrease in mitochondrial function. Thus, we have defined a novel mechanism by which androgens modulate BAD expression, its mitochondria localization, and nuclear content to force its ability to act as a cell cycle inhibitor, strengthening the protective role of androgen signaling in estrogen-responsive BCs.

SIRT1 is involved in adrenocortical cancer growth and motility

Adrenocortical cancer (ACC) is a rare tumour with unfavourable prognosis, lacking an effective treatment. This tumour is characterized by IGF‐II (insulin‐like growth factor II) overproduction, aromatase and ERα (oestrogen receptor alpha) up‐regulation. Previous reports suggest that ERα expression can be regulated by sirt1 (sirtuin 1), a nicotinamide adenine dinucleotide (NAD+)‐dependent class III histone deacetylases that modulates activity of several substrates involved in cellular stress, metabolism, proliferation, senescence, protein degradation and apoptosis. Nevertheless, sirt1 can act as a tumour suppressor or oncogenic protein. In this study, we found that in H295R and SW13 cell lines, sirt1 expression is inhibited by sirtinol, a potent inhibitor of sirt1 activity. In addition, sirtinol is able to decrease ACC cell proliferation, colony and spheroids formation and to activate the intrinsic apoptotic mechanism. Particularly, we observed that sirtinol interferes with E2/ERα and IGF1R (insulin growth factor 1 receptor) pathways by decreasing receptors expression. Sirt1 involvement was confirmed by using a specific sirt1 siRNA. More importantly, we observed that sirtinol can synergize with mitotane, a selective adrenolitic drug, in inhibiting adrenocortical cancer cell growth. Collectively, our data reveal an oncogenic role for sirt1 in ACC and its targeting could implement treatment options for this type of cancer.

Role of GPER-Mediated Signaling in Testicular Functions and Tumorigenesis

Estrogen signaling plays important roles in testicular functions and tumorigenesis. Fifteen years ago, it was discovered that a member of the G protein-coupled receptor family, GPR30, which binds also with high affinity to estradiol and is responsible, in part, for the rapid non-genomic actions of estrogens. GPR30, renamed as GPER, was detected in several tissues including germ cells (spermatogonia, spermatocytes, spermatids) and somatic cells (Sertoli and Leydig cells). In our previous review published in 2014, we summarized studies that evidenced a role of GPER signaling in mediating estrogen action during spermatogenesis and testis development. In addition, we evidenced that GPER seems to be involved in modulating estrogen-dependent testicular cancer cell growth; however, the effects on cell survival and proliferation depend on specific cell type. In this review, we update the knowledge obtained in the last years on GPER roles in regulating physiological functions of testicular cells and its involvement in neoplastic transformation of both germ and somatic cells. In particular, we will focus our attention on crosstalk among GPER signaling, classical estrogen receptors and other nuclear receptors involved in testis physiology regulation.

SUN-931 Characterization of an Ovarian Steroid Cell Tumor in a VHL Patient

Most ovarian steroid cell tumors arise sporadically. However, they can also be observed as a rare manifestation of von Hippel Lindau disease. Here, we present a clinical, pathological and molecular characterization of a steroid cell tumor in a VHL patient. A 14 year old girl with molecularly confirmed diagnosis of VHL developed hirsutism and amenorrhea. Initial clinical hormonal evaluation was notable for elevated 17-OHP of 406ng/dl, androstenedione 275ng/dl, and testosterone 102ng/dl. In order to exclude congenital adrenal hyperplasia as a common cause of hirsutism in adolescents, ACTH stimulation was performed, but no increase in 17-OHP was observed. Anti Muellerian hormone, inhibin (INH) A and INH B were normal. Imaging revealed a bilobed 6cm left adnexal mass. The mass was resected en bloc via a left oophorectomy. Pathological evaluation showed multinodular steroid cell tumor with clear cytoplasm and delicate vascular meshwork. Immunoprofiling demonstrated positivity for inhibin and calretinin; while renal cell carcinoma markers were negative. All laboratory values normalized post-surgery. In addition to clinical measurements pre- and post-surgery, steroid profiles were evaluated by LC-MS/MS. Quantitative RT-PCR analysis showed robust tumor expression of enzymes facilitating the production of androgens, but not estrogens. Further preliminary analysis by exome sequencing confirmed the known germline pathogenic variant in VHL, but no additional obvious somatic driver mutations were identified. Interestingly, the NGS analysis of different specimens from the same tumor revealed multiple different single base pair variants in the VHL gene as a second hit. In summary, hirsutism in VHL patients should raise the suspicion for unusual ovarian tumors. In contrary to the usual theory of a monoclonal expansion after loss of the wt VHL allele, this tumor appeared to be oligoclonal as evidenced by different somatic VHL mutations. This could be either explained by initial parallel occurrence of several clones or that the VHL second hit is not an initial event, but the mutation instead supports tumor expansion following initial steps of tumorigenesis.