Androgen production in pediatric adrenocortical tumors may occur via both the classic and/or the alternative backdoor pathway

Advances in translational research of the rare cancer type adrenocortical carcinoma

Adrenocortical carcinoma is a rare malignancy with an annual worldwide incidence of 1-2 cases per 1 million and a 5-year survival rate of <60%. Although adrenocortical carcinoma is rare, such rare cancers account for approximately one third of patients diagnosed with cancer annually. In the past decade, there have been considerable advances in understanding the molecular basis of adrenocortical carcinoma. The genetic events associated with adrenocortical carcinoma in adults are distinct from those of paediatric cases, which are often associated with germline or somatic TP53 mutations and have a better prognosis. In adult primary adrenocortical carcinoma, the main somatic genetic alterations occur in genes that encode proteins involved in the WNT-β-catenin pathway, cell cycle and p53 apoptosis pathway, chromatin remodelling and telomere maintenance pathway, cAMP-protein kinase A (PKA) pathway or DNA transcription and RNA translation pathways. Recently, integrated molecular studies of adrenocortical carcinomas, which have characterized somatic mutations and the methylome as well as gene and microRNA expression profiles, have led to a molecular classification of these tumours that can predict prognosis and have helped to identify new therapeutic targets. In this Review, we summarize these recent translational research advances in adrenocortical carcinoma, which it is hoped could lead to improved patient diagnosis, treatment and outcome.

Approach to the Virilizing Girl at Puberty

Virilization is the medical term for describing a female who develops characteristics associated with male hormones (androgens) at any age, or when a newborn girl shows signs of prenatal male hormone exposure at birth. In girls, androgen levels are low during pregnancy and childhood. A first physiologic rise of adrenal androgens is observed at the age of 6 to 8 years and reflects functional activation of the zona reticularis of the adrenal cortex at adrenarche, manifesting clinically with first pubic and axillary hairs. Early adrenarche is known as "premature adrenarche." It is mostly idiopathic and of uncertain pathologic relevance but requires the exclusion of other causes of androgen excess (eg, nonclassic congenital adrenal hyperplasia) that might exacerbate clinically into virilization. The second modest physiologic increase of circulating androgens occurs then during pubertal development, which reflects the activation of ovarian steroidogenesis contributing to the peripheral androgen pool. However, at puberty initiation (and beyond), ovarian steroidogenesis is normally devoted to estrogen production for the development of secondary female bodily characteristics (eg, breast development). Serum total testosterone in a young adult woman is therefore about 10- to 20-fold lower than in a young man, whereas midcycle estradiol is about 10- to 20-fold higher. But if androgen production starts too early, progresses rapidly, and in marked excess (usually more than 3 to 5 times above normal), females will manifest with signs of virilization such as masculine habitus, deepening of the voice, severe acne, excessive facial and (male typical) body hair, clitoromegaly, and increased muscle development. Several medical conditions may cause virilization in girls and women, including androgen-producing tumors of the ovaries or adrenal cortex, (non)classical congenital adrenal hyperplasia and, more rarely, other disorders (also referred to as differences) of sex development (DSD). The purpose of this article is to describe the clinical approach to the girl with virilization at puberty, focusing on diagnostic challenges. The review is written from the perspective of the case of an 11.5-year-old girl who was referred to our clinic for progressive, rapid onset clitoromegaly, and was then diagnosed with a complex genetic form of DSD that led to abnormal testosterone production from a dysgenetic gonad at onset of puberty. Her genetic workup revealed a unique translocation of an abnormal duplicated Y-chromosome to a deleted chromosome 9, including the Doublesex and Mab-3 Related Transcription factor 1 (DMRT1) gene.

LEARNING OBJECTIVES

Identify the precise pathophysiologic mechanisms leading to virilization in girls at puberty considering that virilization at puberty may be the first manifestation of an endocrine active tumor or a disorder/difference of sex development (DSD) that remained undiagnosed before and may be life-threatening. Of the DSDs, nonclassical congenital adrenal hyperplasia occurs most often.Provide a step-by-step diagnostic workup plan including repeated and expanded biochemical and genetic tests to solve complex cases.Manage clinical care of a girl virilizing at puberty using an interdisciplinary team approach.Care for complex cases of DSD manifesting at puberty, such as the presented girl with a Turner syndrome-like phenotype and virilization resulting from a complex genetic variation.

Update on adrenarche

PURPOSE OF REVIEW

Adrenarche is the pubertal maturation of the innermost zone of the adrenal cortex, the zona reticularis. The onset of adrenarche occurs between 6 and 8 years of age when dehydroepiandrosterone sulfate (DHEAS) concentrations increase. This review provides an update on adrenal steroidogenesis and the differential diagnosis of premature development of pubic hair.

RECENT FINDINGS

The complexity of adrenal steroidogenesis has increased with recognition of the alternative 'backdoor pathway' and the 11-oxo-androgens pathways. Traditionally, sulfated steroids such as DHEAS have been considered to be inactive metabolites. Recent data suggest that intracellular sulfated steroids may function as tissue-specific intracrine hormones particularly in the tissues expressing steroid sulfatases such as ovaries, testes, and placenta.

SUMMARY

The physiologic mechanisms governing the onset of adrenarche remain unclear. To date, no validated regulatory feedback mechanism has been identified for adrenal C19 steroid secretion. Available data indicate that for most children, premature adrenarche is a benign variation of development and a diagnosis of exclusion. Patients with premature adrenarche tend to have higher BMI values. Yet, despite greater knowledge about C19 steroids and zona reticularis function, much remains to be learned about adrenarche.

In silico and functional studies reveal novel loss-of-function variants of SRD5A2, but no variants explaining excess 5α-reductase activity

Androgens are steroid hormones essential for human male and female development. Steroid reductases 5α (SRD5As) are key enzymes in androgen biosynthesis. Mutations in the human SRD5A2 are known to cause loss-of-function and severe 46,XY undervirilization. Gain-of-function variants have been suggested in androgen excess syndromes, but have not been found so far. Therefore we searched for gain-of-function mutations in the human SRD5A2 gene which might explain hyperandrogenic disorders such as the polycystic ovary syndrome, premature adrenarche and prostate cancer. We screened databases for candidate variants and characterised them in silico with the help of a novel SRD5A2 model. We selected 9 coding SNPs (A49T, R50A, P106L, P106A, N122A, L167S, R168C, P173S, R227Q) that have not been described in manifesting individuals, and assessed their enzyme kinetic properties in HEK293 cells. SRD5A2 activity was assessed by conversion of testosterone (T), progesterone (Prog) and androstenedione (Δ4A) to their 5α-reduced metabolites. Variants R50A and P173S showed partial activity with substrates T (34% and 28%) and Δ4A (37% and 22%). With substrate Prog variants P106L, P106A, L167S and R168C in addition showed partial activity (15% to 64%). Functional testing of all other variants showed loss-of-function. As predicted in our in silico analysis, all coding SNPs affected enzyme activity, however none of them showed gain-of-function. Thus excess 5α-reductase activity might be rather regulated at the (post)-transcriptional and/or post-translational level. However through this work seven new coding SNPs were characterised which might be of clinical relevance. It is possible that individuals carrying these SNPs show a minor phenotype that is not yet identified.

Human Adrenal Cortex: Epigenetics and Postnatal Functional Zonation

The human adrenal cortex, involved in adaptive responses to stress, fluid homeostasis, and secondary sexual characteristics, arises from a tightly regulated development of a zone and cell type-specific secretory pattern. However, the molecular mechanisms governing adrenal zonation, particularly postnatal zona reticularis development, which produce adrenal androgens in a lifetime-specific manner, remain poorly understood. Epigenetic events, including DNA and histone modifications as well as regulation by noncoding RNAs, are crucial in establishing or maintaining the expression pattern of specific genes and thus contribute to the stability of a specific differentiation state. Emerging evidence points to epigenetics as another regulatory layer that could contribute to establishing the adrenal zone-specific pattern of enzyme expression. Here, we outline the developmental milestones of the human adrenal cortex, focusing on current advances and understanding of epigenetic regulation of postnatal functional zonation. Numerous questions remain to be addressed emphasizing the need for additional investigations to elucidate the role of epigenetics in the human adrenal gland. Ultimately, improved understanding of the epigenetic factors involved in adrenal development and function could lead to novel therapeutic interventions.