A review of the effects and molecular mechanisms of dimethylcurcumin (ASC-J9) on androgen receptor-related diseases

Dimethylcurcumin (ASC-J9) is a curcumin analogue capable of inhibiting prostate cancer cell proliferation. The mechanism is associated with the unique role of ASC-J9 in enhancing androgen receptor (AR) degradation. So far, ASC-J9 has been investigated in typical AR-associated diseases such as prostate cancer, benign prostatic hypertrophy, bladder cancer, renal diseases, liver diseases, cardiovascular diseases, cutaneous wound, spinal and bulbar muscular atrophy, ovarian cancer and melanoma, exhibiting great potentials in disease control. In this review, the effects and molecular mechanisms of ASC-J9 on various AR-associated diseases are summarized. Importantly, the effects of ASC-J9 and AR antagonists enzalutamide/bicalutamide on prostate cancer are compared in detail and crucial differences are highlighted. At last, the pharmacological effects of ASC-J9 are summarized and the future applications of ASC-J9 in AR-associated disease control are discussed.

Relevance of low testosterone to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a condition where there is excess accumulation of triglycerides in the liver in the absence of excess alcohol consumption. It ranges from simple steatosis to non-alcoholic steatohepatitis (NASH), which can progress to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). NAFLD, one of the most common causes of chronic liver disease in Western populations, is the hepatic component of the metabolic syndrome (MetS) and is associated with increased visceral adipose tissue (VAT), insulin resistance, and dyslipidemia. Studies have also shown that testosterone deficiency is associated with increased VAT and insulin resistance in males while hyperandrogenemia has been associated with increased risk of insulin resistance and VAT in females. Thus, the aims of this review are to discuss the available experimental and epidemiological data evaluating the association between testosterone and NAFLD, to discuss the potential clinical relevance of these data, and to identify gaps in the literature.

Free testosterone: clinical utility and important analytical aspects of measurement

Testosterone, the most abundant androgen in men, is a steroid hormone that is synthesized predominantly by the testes. In women, minor amounts are synthesized in the ovaries. Androgen precursors are also produced and secreted from the adrenal glands in both sexes, where they undergo peripheral conversion to testosterone. Circulating concentrations are approximately 15-25 times higher in adult men compared to women. Maintenance of these levels is necessary for development and maintenance of secondary sexual characteristics, libido, growth, prevention of osteoporosis, and most importantly in men, spermatogenesis. Most testosterone circulates tightly bound to sex hormone-binding globulin (SHBG) or weakly bound to albumin. A minor amount circulates as free testosterone, and it is believed that this is the metabolically active fraction. Measurement of free testosterone is important in the diagnosis of many diseases, most importantly disorders of androgen deficiency in men (i.e., hypogonadism) and androgen excess in women (i.e., polycystic ovary syndrome and hirsutism). Many methodologies are available for free testosterone measurement including the reference methods (equilibrium dialysis and ultrafiltration), analog immunoassay, and calculated free testosterone based on measurement of total testosterone, SHBG, and albumin. Moreover, measurement of bioavailable testosterone, a combination of albumin-bound and free testosterone, also has clinical utility and can be measured by selective protein precipitation or calculation. In this review, the advantages and limitations of each of these methods will be discussed in the context of clinical utility and implementation into a routine hospital laboratory. Furthermore, up and coming methodologies for free testosterone measurement, including liquid chromatography-tandem mass spectrometry, will also be discussed.

Calculation of bioavailable and free testosterone in men: a comparison of 5 published algorithms

BACKGROUND

Estimation of serum concentrations of free testosterone (FT) and bioavailable testosterone (bioT) by calculation is an inexpensive and uncomplicated method. We compared results obtained with 5 different algorithms.

METHODS

We used 5 different published algorithms [described by Sodergard et al. (bioTS and FTS), Vermeulen et al. (bioTV and FTV), Emadi-Konjin et al. (bioTE), Morris et al. (bioTM), and Ly et al. (FTL)] to estimate bioT and FT concentrations in samples obtained from 399 independently living men (ages 40-80 years) participating in a cross-sectional, single-center study.

RESULTS

Mean bioT was highest for bioTS (10.4 nmol/L) and lowest for bioT(E) (3.87 nmol/L). Mean FT was highest for FTS (0.41 nmol/L), followed by FTV (0.35 nmol/L), and FTL (0.29 nmol/L). For bioT concentrations, the Pearson correlation coefficient was highest for the association between bioTS and bioTV (r = 0.98) and lowest between bioTM and bioTE (r = 0.66). FTL was significantly associated with both FTS (r = 0.96) and FTV (r = 0.88). The Pearson correlation coefficient for the association between FTL and bioTM almost reached 1.0. Bland-Altman analysis showed large differences between the results of different algorithms. BioTM, bioTE, bioTV, and FTL were all significantly associated with sex hormone binding globulin (SHBG) concentrations.

CONCLUSION

Algorithms to calculate FT and bioT must be revalidated in the local setting, otherwise over- or underestimation of FT and bioT concentrations can occur. Additionally, confounding of the results by SHBG concentrations may be introduced.

Measurement of testosterone and its sub-fractions in Canada

Interest in measuring bioactive testosterone in aging males has increased considerably in the last 5 years in Canada. Emerging andropause clinics have submerged our laboratories with requests for bioavailable testosterone (BAT) testing in replacement or addition to the traditional total testosterone (TT) and direct free testosterone (FT) assays. Beginning with a brief explanation of the bioavailability concept of Pardridge, this review examines the technical characteristics of various approaches currently available to measure TT and its sub-fractions. First, limitations in the measurement of TT, SHBG, and particularly direct (analog) FT assays are extracted from the scientific literature and recent external and internal QC reports. It is concluded that the free direct T assay is useless in the clinical context of andropause. The impact of the observed limitations of TT and SHBG measurements on calculated FT and BAT or BAT obtained by precipitation with ammonium sulfate is then discussed. A comparative evaluation of the advantages and disadvantages of calculated FT or BAT vs. precipitated BAT is presented before concluding that doing a TT as a first line test remains overall the most cost-effective measurement in the diagnosis of hypogonadism in males, and that this sole determination will be sufficient in over 75% of the cases.

When is bioavailable testosterone a redundant test in the diagnosis of hypogonadism in men?

OBJECTIVES

Total testosterone (TT) is frequently prescribed with an SHBG and/or free or bioavailable testosterone measurement. Our objective was to identify a TT range for which subsequent SHBG measurement/calculation adds no additional clinical information.

DESIGN AND METHODS

Study data were composed of 3955 sets of TT, SHBG and calculated bioavailable testosterone (cBAT) results from unscreened ambulatory male subjects, aged 18-99.

RESULTS

90% of mismatches between TT and cBAT were observed with TT levels between 6.5 and 13.0 nmol/L, with only slight age variation and no important change with albumin level. SHBG measurement restricted to male patients with TT between 6.5 and 13.0 nmol/L should enable reagent cost savings of over 55%.

CONCLUSION

We suggest that a TT level below 6.5 nmol/L or above 13.0 nmol/L provides sufficient useful information for ruling out hypogonadism in ambulatory adult males. This strategy of BAT testing should lead to significant time and cost savings.

Evaluation of an algorithm for calculation of serum “Bioavailable” testosterone (BAT)

OBJECTIVES

To evaluate a recently published algorithm for calculation of serum "Bioavailable" Testosterone (BAT) using serum Total Testosterone (TT), Sex Steroid Binding Globulin (SSBG) [also commonly known as Sex Hormone Binding Globulin (SHBG)] and albumin concentrations as parameters, in comparison with a locally available "salting-out" BAT method. If satisfactory, this calculation could serve as a substitute for the BAT assay, which would amount to a major cost saving and faster turnaround time.

DESIGN AND METHODS

During a 6-month period, 426 serum samples referred for BAT analysis to the Hospitals In-Common Laboratory of Toronto were also analyzed in-house for TT, SSBG and albumin for computation of comparison calculated BAT results.

RESULTS

A good statistical correlation was obtained, but only after unexpectedly drastic empirical modification of the association constant values: r=0.95, Calculated %BAT=0.971 x Measured %BAT + 0.008. The endocrinologist/andrologist of our team (JB), who was the responsible physician for all patients included in this study, reviewed the tabulated and charted calculated BAT results and verified that they were clinically equivalent.

CONCLUSIONS

Although it is feasible to calculate BAT, the algorithm is not directly portable. Before adopting such a calculation each laboratory should compare it with the locally available BAT method and consider adjusting the calculation to optimize the correlation. Future reassessment may be necessary whenever the SSBG, TT or BAT assay is changed.