Androgen deprivation therapy in prostate cancer and metabolic risk for atherosclerosis.

CONTEXT: Prostate cancer (PCa) is the most common cancer in men. Androgen-deprivation therapy (ADT) is generally employed in the treatment of locally advanced and metastatic PCa. Although its use as an adjuvant therapy has resulted in improved survival in some patients, ADT has negative consequences. Complications like osteoporosis, sexual dysfunction, gynecomastia, and adverse body composition are well known. Recently, metabolic complications like insulin resistance, diabetes, dyslipidemia, and metabolic syndrome have emerged, which may be responsible for the increased cardiovascular mortality in this population. EVIDENCE ACQUISITION: A MEDLINE search was conducted for articles published over the last 20 yr based on the key words androgen deprivation therapy AND insulin resistance, hyperglycemia, diabetes, dyslipidemia, metabolic syndrome, and cardiovascular disease. Relevant studies in non-PCa populations evaluating the association between testosterone and metabolism were also reviewed and briefly mentioned where relevant. EVIDENCE SYNTHESIS: Prospective studies evaluating early (3-6 months) metabolic changes of ADT show development of hyperinsulinemia; however, glucose levels remain normal. Cross-sectional studies of men undergoing long-term (> or =12 months) ADT reveal higher prevalence of diabetes and metabolic syndrome compared with controls. Furthermore, men undergoing ADT also experience higher cardiovascular mortality. CONCLUSION: Long-term prospective studies of ADT are needed to determine the timing of onset of these metabolic complications and to investigate the mechanism behind them. In the meantime, we recommend baseline and serial screening for fasting glucose, lipids, and other cardiovascular risk factors in men receiving ADT. Glucose tolerance tests and cardiac evaluation may be required in selected cases.

Endocrine complications of androgen-deprivation therapy in men with prostate cancer.

Prostate cancer is one of the most common cancers in men. Androgen-deprivation therapy (ADT) is often employed in the treatment of recurrent and metastatic prostate cancer. Although its use as an adjuvant therapy has resulted in improved survival in a subset of patients, ADT also results in a multitude of endocrine complications. These complications affect quality of life and sense of well-being in these men. Some of the endocrine complications of ADT such as osteoporosis, sexual dysfunction, hot flashes, gynecomastia, and adverse body composition are well-known. Recently, insulin resistance, hyperglycemia, and metabolic syndrome have emerged as metabolic complications of castration and may be responsible for increased cardiovascular mortality in this population. In this article, we provide a detailed review of the endocrine complications of ADT, touching upon management strategies where applicable.

NF-kappaB-inducing kinase (NIK) mediates skeletal muscle insulin resistance: blockade by adiponectin.

Enhanced levels of nuclear factor (NF)-κB-inducing kinase (NIK), an upstream kinase in the NF-κB pathway, have been implicated in the pathogenesis of chronic inflammation in diabetes. We investigated whether increased levels of NIK could induce skeletal muscle insulin resistance. Six obese subjects with metabolic syndrome underwent skeletal muscle biopsies before and six months after gastric bypass surgery to quantitate NIK protein levels. L6 skeletal myotubes, transfected with NIK wild-type or NIK kinase-dead dominant negative plasmids, were treated with insulin alone or with adiponectin and insulin. Effects of NIK overexpression on insulin-stimulated glucose uptake were estimated using tritiated 2-deoxyglucose uptake. NF-κB activation (EMSA), phosphatidylinositol 3 (PI3) kinase activity, and phosphorylation of inhibitor κB kinase ß and serine-threonine kinase (Akt) were measured. After weight loss, skeletal muscle NIK protein was significantly reduced in association with increased plasma adiponectin and enhanced AMP kinase phosphorylation and insulin sensitivity in obese subjects. Enhanced NIK expression in cultured L6 myotubes induced a dose-dependent decrease in insulin-stimulated glucose uptake. The decrease in insulin-stimulated glucose uptake was associated with a significant decrease in PI3 kinase activity and protein kinase B/Akt phosphorylation. Overexpression of NIK kinase-dead dominant negative did not affect insulin-stimulated glucose uptake. Adiponectin treatment inhibited NIK-induced NF-κB activation and restored insulin sensitivity by restoring PI3 kinase activation and subsequent Akt phosphorylation. These results indicate that NIK induces insulin resistance and further indicate that adiponectin exerts its insulin-sensitizing effect by suppressing NIK-induced skeletal muscle inflammation. These observations suggest that NIK could be an important therapeutic target for the treatment of insulin resistance associated with inflammation in obesity and type 2 diabetes.

Ectopic corticotropin-releasing hormone (CRH) syndrome from metastatic small cell carcinoma: a case report and review of the literature.

BACKGROUND: Cushing's Syndrome (CS) which is caused by isolated corticotropin-releasing hormone (CRH) production, rather than adrenocorticotropin (ACTH) production, is extremely rare. METHODS: We describe the clinical presentation, course, laboratory values and pathologic findings of a patient with isolated ectopic CRH causing CS. We review the literature of the types of tumors associated with this unusual syndrome and the behavior of these tumors by endocrine testing. RESULTS: A 56 year old woman presented with clinical and laboratory features consistent with ACTH-dependent CS. Pituitary imaging was normal and cortisol did not suppress with a high dose dexamethasone test, consistent with a diagnosis of ectopic ACTH. CT imaging did not reveal any discrete lung lesions but there were mediastinal and abdominal lymphadenopathy and multiple liver lesions suspicious for metastatic disease. Laboratory testing was positive for elevated serum carcinoembryonic antigen and the neuroendocrine marker chromogranin A. Serum markers of carcinoid, medullary thyroid carcinoma, and pheochromocytoma were in the normal range. Because the primary tumor could not be identified by imaging, biopsy of the presumed metastatic liver lesions was performed. Immunohistochemistry was consistent with a neuroendocrine tumor, specifically small cell carcinoma. Immunostaining for ACTH was negative but was strongly positive for CRH and laboratory testing revealed a plasma CRH of 10 pg/ml (normal 0 to 10 pg/ml) which should have been suppressed in the presence of high cortisol. CONCLUSIONS: This case illustrates the importance of considering the ectopic production of CRH in the differential diagnosis for presentations of ACTH-dependent Cushing's Syndrome.

The latest options and future agents for treating male hypogonadism.

Exogenous testosterone has long been used in medicine as a pharmaceutical agent. Its use in hypogonadism is well characterized and its development as a drug has undergone several modifications in an attempt to achieve clinical success. As native testosterone is rapidly degraded, modified analogs have been developed to obtain a better pharmacokinetic profile. The developmental goals of testosterone analogs have evolved since its first introduction as an orally available form to longer acting and more stable forms such as injectables, depots and transdermal therapies. Several modalities of testosterone replacement are presently available, each differentiated by their route of delivery, half life, cost and ability to deliver physiologic levels of testosterone. As hypogonadism is often a life-long condition, physicians are compelled to use an appropriate therapy that best matches the needs of their patients. An ideal testosterone therapy should be able to deliver physiologic levels of testosterone and be safe, simple to use and cost effective. Present trends show transdermal therapies (gels and patches) along with long-acting injectables, such as Nebido, are quickly replacing intramuscular testosterone modalities. Compounds such as dihydrotestosterone, human chorionic gonadotropin, aromatase inhibitors and clomiphene are presently being studied in specific subgroups of men. Additionally, several new compounds, such as selective androgen-receptor modulators and 7-alpha-methyl-19-nortestosterone, are being developed to target androgen receptors in specific tissues. A further understanding of the androgen receptor and subsequent discovery of targeted drugs may yield more individualized treatment modalities. This will enhance the effectiveness of available therapies, while mitigating their undesirable effects.