We have previously demonstrated that estrogen receptor (ER) alpha (ESR1) increases proliferation of adrenocortical carcinoma (ACC) through both an estrogen-dependent and -independent (induced by IGF-II/IGF1R pathways) manner. Then, the use of tamoxifen, a selective estrogen receptor modulator (SERM), appears effective in reducing ACC growth in vitro and in vivo. However, tamoxifen not only exerts antiestrogenic activity, but also acts as full agonist on the G protein-coupled estrogen receptor (GPER). Aim of this study was to investigate the effect of a non-steroidal GPER agonist G-1 in modulating ACC cell growth. We found that G-1 is able to exert a growth inhibitory effect on H295R cells both in vitro and, as xenograft model, in vivo. Treatment of H295R cells with G-1 induced cell cycle arrest, DNA damage and cell death by the activation of the intrinsic apoptotic mechanism. These events required sustained extracellular regulated kinase (ERK) 1/2 activation. Silencing of GPER by a specific shRNA partially reversed G-1-mediated cell growth inhibition without affecting ERK activation. These data suggest the existence of G-1 activated but GPER-independent effects that remain to be clarified. In conclusion, this study provides a rational to further study G-1 mechanism of action in order to include this drug as a treatment option to the limited therapy of ACC.

These findings establish a critical role for ERα in E2- and IGF-II-dependent ACC proliferation and provide a rationale for targeting ERα to control the proliferation of ACC.

ARMC5 mutations have recently been identified as a common genetic cause of primary bilateral macronodular adrenal hyperplasia (PBMAH). We aimed to assess the prevalence of ARMC5 germline mutations and correlate genotype with phenotype in a large cohort of PBMAH patients. A multicenter study was performed, collecting patients from different endocrinology units in Italy. Seventy-one PBMAH patients were screened for small mutations and large rearrangements in the ARMC5 gene: 53 were cortisol-secreting (two with a family history of adrenal hyperplasia) and 18 were non-secreting cases of PBMAH. Non-mutated and mutated patients' clinical phenotypes were compared and related to the type of mutation. A likely causative germline ARMC5 mutation was only identified in cortisol-secreting PBMAH patients (one with a family history of adrenal hyperplasia and ten apparently sporadic cases). Screening in eight first-degree relatives of three index cases revealed four carriers of an ARMC5 mutation. Evidence of a second hit at somatic level was identified in five nodules. Mutated patients had higher cortisol levels (p = 0.062), and more severe hypertension and diabetes (p < 0.05). Adrenal glands were significantly larger, with a multinodular phenotype, in the mutant group (p < 0.01). No correlation emerged between type of mutation and clinical parameters. ARMC5 mutations are frequent in cortisol-secreting PBMAH and seem to be associated with a particular pattern of the adrenal masses. Their identification may have implications for the clinical care of PBMAH cases and their relatives.

Mitotane, 1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane (o,p 0 -DDD) is an agent with adrenotoxic effect, which is able to block cortisol synthesis. This drug and radiotherapy are used also in adrenal cancer treatment even if their biological action in this neoplasia remains unknown. We investigated the effects of o,p 0 -DDD and ionizing radiations (IR) on cell growth inhibition and cell cycle perturbation in H295R and SW13 adrenocortical cancer cells. Both cell lines were irradiated at a 6 Gy dose and were treated with o,p 0 -DDD 10 K5 M separately and with IR/o,p 0 -DDD in combination. This combination treatment induced an irreversible inhibition of cell growth in both adrenocortical cancer cells. Cell cycle analysis showed that IR alone and IR/o,p 0 -DDD in combination induced the cell accumulation in the G 2 phase. At 120 h after IR, the cells were able to recover the IR-induced G 2 block while cells treated with IR/o,p 0 -DDD were still arrested in G 2 phase. In order to study the molecular mechanism involved in the G 2 irreversible arrest, we have considered the H295R cell line showing the highest inhibition of cell proliferation associated with a noteworthy G 2 arrest. In these cells, cyclin B1 and Cdk2 proteins were examined by western blot and Cdk2 kinase activity measured by assay kit. The H295R cells treated with IR/o,p 0 -DDD shared an increase in cyclin B1 amount as the coimmunoprecipitation of Cdc2-cyclin B1 complex. The kinase activity also shows an increase in the treated cells with combination therapy. Moreover, in these cells, sequence analysis of p53 revealed a large deletion of exons 8 and 9. The same irreversible block on G 2 phase, induced by IR/o,p 0 -DDD treatment, happened in H295R cells with restored wild-type p53 suggesting that this mechanism is not mediated by p53 pathway.

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