Transcription of androgen receptor and 5alpha-reductase II in genital fibroblasts from patients with androgen insensitivity syndrome

The differential role of androgens in early human sex development

Sexual development in humans is only partly understood at the molecular level. It is dependent on genetic control primarily induced by the sex chromosomal differences between males and females. This leads to the development of the gonads, whereby afterwards the differentiation of the apparent phenotype is controlled by hormone action. Sex steroids may exert permanent and temporary effects. Their organizational features of inducing permanent changes in phenotype occur through genetic control of downstream genes. In this, androgens are the key elements for the differentiation of male internal and external genitalia as well as other sexual organs and general body composition, acting through a single androgen receptor. The androgen receptor is a nuclear transcription factor modulating DNA transcription of respective target genes and thereby driving development and growth in a stringent manner. The specificity of androgen action seems to be a strictly time-controlled process with the androgen receptor acting in concert with different metabolites and an array of cofactors modulating the cellular response and thereby permanently altering the phenotype of any given individual. For every cell programmed by androgens, a specific 'androgen response index' must be proposed.

Transactivation Properties of Wild-Type and Mutant Androgen Receptors in Transiently Transfected Primary Human Fibroblasts

BACKGROUND

Stromal cells play key roles during androgen-mediated male sexual differentiation. Our objective was to establish a transient transfection method for primary human fibroblasts enabling functional characterization of wild-type (wt) and mutant androgen receptor (AR) plasmid constructs, corresponding to partial and complete androgen insensitivity syndrome (PAIS/CAIS).

METHODS

An AR-negative fibroblast strain (ARD842) was established from the gonads of a CAIS patient. Wt-AR or either mutants L712F (PAIS), R774C or V866M (CAIS) were transfected using a polyamine-based procedure. Alternatively, two AR-positive male foreskin fibroblast strains were investigated. Androgen-induced activation of two co-transfected reporter plasmids ((ARE)(2)TATA-, MMTV-luciferase) was measured.

RESULTS

All three fibroblast strains showed a ligand-dependent rise of luciferase activity after transfection of wt-AR. Mutant plasmids were assessed in AR-negative ARD842 cells. While L712F showed high partial activity, R774C and V866M were nearly inactive. The intrinsic AR of normal foreskin fibroblasts revealed no measurable ligand-inducible reporter gene activity.

CONCLUSIONS

Polyamine-based transfection of AR plasmids into cultured fibroblasts provides a promising tool for analysis of AR transactivation, thereby considering a stromal cellular background. This is supported by the mutant ARs which showed the expected levels of impaired transactivation with respect to the corresponding AIS phenotypes. The role of the intrinsic AR in normal male human foreskin fibroblasts needs further exploration.

Mutation of the androgen receptor (R840S) in an Egyptian patient with partial androgen insensitivity syndrome: review of the literature on the clinical expression of different R840 substitutions

The X-linked androgen insensitivity syndrome (AIS) encompasses a heterogeneous group of defects in the androgen receptor (AR) that result in varying degrees of undermasculinization. In the current study, we characterize the R840S mutation on exon 7 of the AR ligand-binding domain. The Egyptian patient, who had been reared as female, presented ambiguous genitalia at 6.5 yr. Diagnosis of partial AIS (PAIS) was based on clinical phenotype and laboratory evidence of good testosterone response and normal testosterone/dihydrotestosterone (T/DHT) ratio. The therapeutic response to testosterone depot injections justified reassignment to male sex. To our knowledge, this mutation has been reported only once in two Brazilian brothers with PAIS. Three other mutations of this residue (R840C; R840G, nonconservative; and R840H, conservative) have been reported in patients with PAIS and, when expressed in vitro, they led to subnormal transactivation of a reporter gene. Each of these mutations was associated with a very diverse spectrum of phenotypes. These data highlight the role of the AR ligand-binding pocket (LBP) in the expression of transcriptional activity during prenatal sex differentiation.

Syndromic aspects of testicular carcinoma

BACKGROUND

In patients with hereditary or constitutional chromosomal anomalies, testicular carcinoma can develop sporadically or on the basis of an underlying hereditary genetic defect. Greater knowledge of these genetic defects would provide more insight into the molecular pathways that lead to testicular carcinoma. To the authors' knowledge, little attention has been paid to date to the comorbid occurrence of testicular carcinoma in patients with hereditary disorders or constitutional chromosomal anomalies.

METHODS

The authors performed a review of the literature.

RESULTS

Twenty-five different hereditary disorders or constitutional chromosomal anomalies have been reported in patients who developed seminomatous or nonseminomatous testicular carcinoma.

CONCLUSIONS

Although most of these malignancies were too rare to enable the detection of statistically significant correlations between the chromosomal/hereditary disorder and the testicular tumor, it was striking that many of the patients had also other urogenital abnormalities. Susceptibility to urogenital abnormalities seems to disrupt normal urogenital differentiation and suggests a correlation with testicular dysgenesis and, thus, also with testicular carcinoma. Other evidence of causal involvement has been found in the field of tumor cytogenetics. Some of the genes responsible for hereditary disorders have been mapped to regions that are of interest in the development of sporadic testicular carcinoma. Molecular studies on candidate genes will be required to provide definite answers. Completion of the human gene map and the availability of advanced gene arrays and bioinformatics are expected to greatly facilitate further exploration of the role of hereditary genetic defects in testicular carcinoma.