Interferon signals to the nucleus by activating the latent cytoplasmic transcription factor Stat1 to induce IFN-responsive genes (1, 2). In addition to function as a transcriptional activator, the transcriptional repression activity of Stat1 has also been documented (3, 4). Furthermore, the involvement of Stat1 in the constitutive transcription of several genes in the absence of ligand stimulation has recently been reported. It is believed that these distinct activities of Stat1 in gene regulation are achieved, in part, by the association of Stat1 with different transcriptional modulators (5, 6). p300 and CREB-binding protein transcriptional coactivators interact with Stat1 to enhance Stat1-mediated gene activation (7,8). The constitutive expression of the low molecular mass polypeptide 2 (LMP2) gene is mediated by a complex of unphosphorylated Stat1 and interferon regulatory factor 1 (IRF1) (9, 10). However, a transcriptional corepressor of a STAT protein has not been uncovered.Two members of the protein inhibitor of activated STAT (PIAS) protein family (5), PIAS1 and PIAS3, have been shown to act as inhibitors of Stat1-and Stat3-mediated gene activation, respectively. PIAS1 and PIAS3 can block the DNA binding activity of STAT in vitro (11,12). Two related proteins named PIASx (consisting of two splicing variants PIASx␣ and PIASx␤) and PIASy have been identified. The role of PIASx or PIASy in STAT signaling is not understood.We report here the characterization of PIASy in STAT signaling. PIASy is localized in the nucleus. Upon IFN stimulation, PIASy becomes associated with Stat1 in vivo. PIASy represses Stat1-mediated gene activation without inhibiting the DNA binding activity of Stat1. An LXXLL coregulator signature motif present at the NH 2 terminus of PIASy, although not involved in PIASy-Stat1 interaction, is required for the repressive activity of PIASy on Stat1-mediated gene activation. Our results suggest that PIASy is a transcriptional corepressor of Stat1. Materials and MethodsPlasmids and Antibodies. Flag-PIASy and Flag-PIASy-AA were constructed by insertion of the human wild-type PIASy cDNA or a mutant PIASy cDNA containing substitutions of the CTC and CTG codons for Leu-23 and Leu-24 to GCC (Ala) and GCG (Ala) into the BamHI and SalI sites of pCMV-Flag vector, respectively. pcDNA3-PIASy and pcDNA3-PIASy-AA were constructed by insertion of the human wild-type or L23L243AA mutant PIASy cDNA into the EcoRI and NotI sites of pcDNA3 vector (Invitrogen).Anti-PIASy antiserum was raised against a recombinant fusion protein of glutathione S-transferase (GST) with the 121 COOHterminal amino acid residues of murine PIASy, the sequence of which was obtained by sequencing EST clone 444894. The resulting antibody can recognize both human and murine PIASy proteins. Anti-pStat1 is from New England Biolabs.Immunofluorescence Analysis. Cells were plated on cover slips coated with fibronectin (10 g/ml) in a 24-well plate and incubated at 37°C for 16 h. Cells were then washed once with 1ϫ PBS, fixed with 3.7% formaldeh...

Timely characterization of a cancer's evolution is required to predict treatment efficacy and to detect resistance early. High content analysis of single Circulating Tumor Cells (CTCs) enables sequential characterization of genotypic, morphometric and protein expression alterations in real time over the course of cancer treatment. This concept was investigated in a patient with castrate-resistant prostate cancer progressing through both chemotherapy and targeted therapy. In this case study, we integrate across four timepoints 41 genome-wide copy number variation (CNV) profiles plus morphometric parameters and androgen receptor (AR) protein levels. Remarkably, little change was observed in response to standard chemotherapy, evidenced by the fact that a unique clone (A), exhibiting highly rearranged CNV profiles and AR+ phenotype was found circulating before and after treatment. However, clinical response and subsequent progression after targeted therapy was associated with the drastic depletion of clone A, followed by the sequential emergence of two distinct CTC sub-populations that differed in both AR genotype and expression phenotype. While AR- cells with flat or pseudo-diploid CNV profiles (clone B) were identified at the time of response, a new tumor lineage of AR+ cells (clone C) with CNV altered profiles was detected during relapse. We showed that clone C, despite phylogenetically related to clone A, possessed a unique set of somatic CNV alterations, including MYC amplification, an event linked to hormone escape. Interesting, we showed that both clones acquired AR gene amplification by deploying different evolutionary paths. Overall, these data demonstrate the timeframe of tumor evolution in response to therapy and provide a framework for the multi-scale analysis of fluid biopsies to quantify and monitor disease evolution in individual patients.

BackgroundProstate cancer patients on androgen deprivation therapy (ADT) experience adverse effects such as lean mass loss, known as sarcopenia, fat gain, and changes in cardiometabolic factors that increase risk of metabolic syndrome (MetS). Resistance training can increase lean mass, reduce body fat, and improve physical function and quality of life, but no exercise interventions in prostate cancer patients on ADT have concomitantly improved body composition and MetS. This pilot trial investigated 12 weeks of resistance training on body composition and MetS changes in prostate cancer patients on ADT. An exploratory aim examined if a combined approach of training and protein supplementation would elicit greater changes in body composition.MethodsProstate cancer patients on ADT were randomized to resistance training and protein supplementation (TRAINPRO), resistance training (TRAIN), protein supplementation (PRO), or control stretching (STRETCH). Exercise groups (EXE = TRAINPRO, TRAIN) performed supervised exercise 3 days per week for 12 weeks, while non-exercise groups (NoEXE = PRO, STRETCH) performed a home-based stretching program. TRAINPRO and PRO received 50 g⋅day− 1 of whey protein. The primary outcome was change in lean mass assessed through dual energy x-ray absorptiometry. Secondary outcomes examined changes in sarcopenia, assessed through appendicular skeletal mass (ASM) index (kg/m2), body fat %, strength, physical function, quality of life, MetS score and the MetS components of waist circumference, blood pressure, glucose, high-density lipoprotein-cholesterol, and triglyceride levels.ResultsA total of 37 participants were randomized; 32 participated in the intervention (EXE n = 13; NoEXE n = 19). At baseline, 43.8% of participants were sarcopenic and 40.6% met the criteria for MetS. Post-intervention, EXE significantly improved lean mass (d = 0.9), sarcopenia prevalence (d = 0.8), body fat % (d = 1.1), strength (d = 0.8–3.0), and prostate cancer-specific quality of life (d = 0.9) compared to NoEXE (p < 0.05). No significant differences were observed between groups for physical function or MetS-related variables except waist circumference (d = 0.8).ConclusionsA 12-week resistance training intervention effectively improved sarcopenia, body fat %, strength and quality of life in hypogonadal prostate cancer patients, but did not change MetS or physical function. PRO did not offer additional benefit in improving body composition.Trial registrationClinicalTrials.gov: NCT01909440. Registered 24 July 2013.

No abstract

Purpose Antiproliferative and antiosteoclastic activity from preclinical models show potential for dasatinib, an oral SRC and SRC family kinase inhibitor, as a targeted therapy for patients with prostate cancer. This phase II study investigated the activity of dasatinib in patients with metastatic castration-resistant prostate cancer (CRPC). Experimental Design Chemotherapy-naive men with CRPC and increasing prostate-specific antigen were treated with dasatinib 100 or 70 mg twice daily. Endpoints included changes in prostate-specific antigen, bone scans, measurable disease (Response Evaluation Criteria in Solid Tumor), and markers of bone metabolism. Following Prostate Cancer Working Group 2 guidelines, lack of progression according to Response Evaluation Criteria in Solid Tumor and bone scan was determined and reported at 12 and 24 weeks. Results Forty-seven patients were enrolled and received dasatinib (initial dose 100 mg twice daily, n = 25; 70 mg twice daily, n = 22), of whom 41 (87%) had bone disease. Lack of progression was achieved in 20 (43%) patients at week 12 and in 9 (19%) patients at week 24. Of 41 evaluable patients, 21 (51%) patients achieved ≥40% reduction in urinary N-telopeptide by week 12, with 33 (80%) achieving some level of reduction anytime on study. Of 15 patients with elevated urinary N-telopeptide at baseline, 8 (53%) normalized on study. Of 40 evaluable patients, 24 (60%) had reduction in bone alkaline phosphatase at week 12 and 25 (63%) achieved some reduction on study. Dasatinib was generally well tolerated and treatment-related adverse events were moderate. Conclusions This study provides encouraging evidence of dasatinib activity in bone and reasonable tolerability in chemotherapy-naive patients with metastatic CRPC.