The androgen receptor (AR) plays a key role in progression to incurable androgen ablation-resistant prostate cancer (PCA). We have identified three novel AR splice variants lacking the ligand-binding domain (designated as AR3, AR4, and AR5) in hormone-insensitive PCA cells. AR3, one of the major splice variants expressed in human prostate tissues, is constitutively active, and its transcriptional activity is not regulated by androgens or antiandrogens. Immunohistochemistry analysis on tissue microarrays containing 429 human prostate tissue samples shows that AR3 is significantly up-regulated during PCA progression and AR3 expression level is correlated with the risk of tumor recurrence after radical prostatectomy. Overexpression of AR3 confers ablation-independent growth of PCA cells, whereas specific knockdown of AR3 expression (without altering AR level) in hormone-resistant PCA cells attenuates their growth under androgen-depleted conditions in both cell culture and xenograft models, suggesting an indispensable role of AR3 in ablation-independent growth of PCA cells. Furthermore, AR3 may play a distinct, yet essential, role in ablation-independent growth through the regulation of a unique set of genes, including AKT1, which are not regulated by the prototype AR. Our data suggest that aberrant expression of AR splice variants may be a novel mechanism underlying ablation independence during PCA progression, and AR3 may serve as a prognostic marker to predict patient outcome in response to hormonal therapy. Given that these novel AR splice variants are not inhibited by currently available antiandrogen drugs, development of new drugs targeting these AR isoforms may potentially be effective for treatment of ablation-resistant PCA. [Cancer Res 2009;69(6):2305-13]

BACKGROUND We wanted to determine the type of outpatient medical care reported by young adult survivors of childhood cancer and to examine factors associated with limited medical care. METHODS We analyzed data from 9,434 adult childhood cancer survivors enrolled in a retrospective cohort study who completed a baseline questionnaire. They had a mean age of 26.8 years (range 18 to 48 years), 47% were female, 12% were minorities, and 16% were uninsured. Four self-reported outcome measures were used to determine outpatient medical care in a 2-year period: general contact with the health care system, general physical examination, cancer-related medical visit, and medical visit at a cancer center. RESULTS Eighty-seven percent reported general medical contact, 71.4% a general physical examination, 41.9% a cancer-related visit, and 19.2%, a visit at a cancer center. Factors associated with not reporting a general physical examination, a cancer-related visit, or a cancer center visit included no health insurance (odds ratio [OR] = 2.34; 95% confi dence interval [CI], 1.97-2.77), male sex (OR = 1.65; 95% CI, 1.44-1.88), lack of concern for future health (OR = 1.57; 95% CI, 1.36-1.82), and age 30 years or older in comparison with those 18 to 29 years (OR = 1.56; 95% CI, 1.35-1.81). The likelihood of reporting a cancer-related visit or a general physical examination decreased signifi cantly as the survivor aged or the time from cancer diagnosis increased. This trend was also signifi cant for those treated with therapies associated with substantial risk for cardiovascular disease or breast cancer. CONCLUSIONS Primary care physicians provide health care for most of this growing high-risk population. To optimize risk-based care, it is critical that cancer centers and primary care physicians develop methods to communicate effectively and longitudinally. 62 ADULT CHILDHOOD CANCER SURVIVORS absolute excess risk for mortality from second cancers (not including late recurrences), cardiac causes, and pulmonary causes of 1.26, 0.27, and 0.015 deaths, respectively, per 1,000 person-years. Morbidity secondary to late effects of chemotherapy or radiation is frequent and often serious. In 5 studies reporting on long-term survivors with a median age ranging from 15 to 23 years, 58% to 69% had at least one late effect of therapy, with 25% to 30% experiencing a moderate to severe late complication. 4-8 Hudson et al 9 found that 44% of adult survivors of childhood cancer reported at least one domain of their health status to be moderately to extremely adversely affected. Survivors can benefi t from early diagnosis and intervention or preventive care targeted at reducing risk for late effects, such as second malignant neoplasms of the breast, 10,11 thyroid, 12,13 and skin 14,15 after radiation therapy; altered bone metabolism and osteoporosis 16,17 ; obesity-related health problems (dyslipidemia, hyper-tension, diabetes mellitus, cardiovascular disease) 18-20 ; liver failure secondary to chronic hepatitis C after blood transfusion 21 ; and en...

The androgen receptor (AR) is essential for the growth of prostate cancer cells. Here, we report that tyrosine phosphorylation of AR is induced by growth factors and elevated in hormone-refractory prostate tumors. Mutation of the major tyrosine phosphorylation site in AR significantly inhibits the growth of prostate cancer cells under androgen-depleted conditions. The Src tyrosine kinase appears to be responsible for phosphorylating AR, and there is a positive correlation of AR tyrosine phosphorylation with Src tyrosine kinase activity in human prostate tumors. Our data collectively suggest that growth factors and their downstream tyrosine kinases, which are elevated during hormone-ablation therapy, can induce tyrosine phosphorylation of AR and such modification may be important for prostate tumor growth under androgen-depleted conditions.

Summary The androgen receptor (AR) plays a critical role in prostate cancer. We have identified an ubiquitin E3 ligase RNF6 as one of AR-associated proteins in a proteomic screen. RNF6 induces AR ubiquitination and promotes AR transcriptional activity. Specific knockdown of RNF6 or mutation of RNF6-induced ubiquitination acceptor sites on AR selectively alters expression of a subset of AR target genes and diminishes recruitment of AR and its coactivators to androgen-responsive elements present in the regulatory region of these genes. Furthermore, RNF6 is overexpressed in human hormone-refractory prostate cancer tissues and required for prostate cancer cell growth under androgen-depleted conditions. Our data suggest that RNF6-induced ubiquitination may regulate AR transcriptional activity and specificity through modulating co-factor recruitment.