Castration-resistant prostate cancer: Androgen receptor inactivation induces telomere DNA damage, and damage response inhibition leads to cell death

Telomere stability is important for cell viability, as cells with telomere DNA damage that is not repaired do not survive. We reported previously that androgen receptor (AR) antagonist induces telomere DNA damage in androgen-sensitive LNCaP prostate cancer cells; this triggers a DNA damage response (DDR) at telomeres that includes activation of ATM, and blocking ATM activation prevents telomere DNA repair and leads to cell death. Remarkably, AR antagonist induces telomere DNA damage and triggers ATM activation at telomeres also in 22Rv1 castration-resistant prostate cancer (CRPC) cells that are not growth inhibited by AR antagonist. Treatment with AR antagonist enzalutamide (ENZ) or ATM inhibitor (ATMi) by itself had no effect on growth in vitro or in vivo, but combined treatment with ENZ plus ATMi significantly inhibited cell survival in vitro and tumor growth in vivo. By inducing telomere DNA damage and activating a telomere DDR, an opportunity to inhibit DNA repair and promote cell death was created, even in CRPC cells. 22Rv1 cells express both full-length AR and AR splice variant AR-V7, but full-length AR was found to be the predominant form of AR associated with telomeres and required for telomere stability. Although 22Rv1 growth of untreated 22Rv1 cells appears to be driven by AR-V7, it is, ironically, expression of full-length AR that makes them sensitive to growth inhibition by combined treatment with ENZ plus ATMi. Notably, this combined treatment approach to induce telomere DNA damage and inhibit the DDR was effective in inducing cell death also in other CRPC cell lines (LNCaP/AR and C4-2B). Thus, the use of ENZ in combination with a DDR inhibitor, such as ATMi, may be effective in prolonging disease-free survival of patients with AR-positive metastatic CRPC, even those that co-express AR splice variant

Effects of Additional Pleurodesis with Dextrose and Talc-Dextrose Solution after Video Assisted Thoracoscopic Procedures for Primary Spontaneous Pneumothorax

Recurrence after thoracoscopic surgery for primary spontaneous pneumothorax is a lingering problem, and many intraoperative methods to induce pleural symphysis have been introduced. We analyzed the effects of chemical pleurodesis during thoracoscopic procedures. Between August 2003 and July 2005, 141 patients among indicated surgical treatment for primary spontaneous pneumothorax in two hospitals of our institution allowed this prospective study. The patients were randomly assigned to 3 groups: thoracoscopic procedure only (group A, n=50), thoracoscopic procedure and pleurodesis with dextrose solution (group B, n=49), and thoracoscopic procedure and pleurodesis with talc-dextrose mixed solution (group C, n=42). There was no significant difference in demographic data among the three groups. The two groups that underwent intraoperative pleurodesis had significantly longer postoperative hospital stays (A/B/C: 2.50±1.85/4.49±2.10/6.00±2.58 days; p=0.001) and a higher incidence of postoperative fever (A/B/C: 10.0/22.45/52.38%; χ2=21.598, p=0.00). No significant differences were found for recurrence rates or the number of postoperative days until chest tube removal. Therefore, the results of our study indicate that intraoperative chemical pleurodesis gives no additional advantage to surgery alone in deterring recurrence for patients with primary spontaneous pneumothorax. Thus, the use of such scarifying agents in the operating room must be reconsidered

Telomere dysfunction and cell survival: roles for distinct TIN2-containing complexes

Telomeres are maintained by three DNA-binding proteins (telomeric repeat binding factor 1 [TRF1], TRF2, and protector of telomeres 1 [POT1]) and several associated factors. One factor, TRF1-interacting protein 2 (TIN2), binds TRF1 and TRF2 directly and POT1 indirectly. Along with two other proteins, TPP1 and hRap1, these form a soluble complex that may be the core telomere maintenance complex. It is not clear whether subcomplexes also exist in vivo. We provide evidence for two TIN2 subcomplexes with distinct functions in human cells. We isolated these two TIN2 subcomplexes from nuclear lysates of unperturbed cells and cells expressing TIN2 mutants TIN2-13 and TIN2-15C, which cannot bind TRF2 or TRF1, respectively. In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere dysfunction and cell death. Our findings suggest that distinct TIN2 complexes exist and that TIN2-15C–sensitive subcomplexes are particularly important for cell survival in the absence of functional p53

Pharmacokinetic evaluation of paclitaxel, albumin-binding paclitaxel, and liposomal-encapsulated albumin-binding paclitaxel upon gastric subserosal administration

Introduction: Systemic chemotherapy is typically administered following radical gastrectomy for advanced stage. To attenuate systemic side effects, we evaluated the effectiveness of regional chemotherapy using paclitaxel, albumin-paclitaxel, and liposome-encapsulated albumin-paclitaxel via subserosal injection in rat models employing nuclear medicine and molecular imaging technology.Method: Nine Sprague Dawley rats were divided into three groups: paclitaxel (n = 3), albumin-paclitaxel nano-particles (APNs; n = 3), and liposome-encapsulated APNs (n = 3). [123I]Iodo-paclitaxel ([123I]I-paclitaxel) was synthesized by conventional electrophilic radioiodination using tert-butylstannyl substituted paclitaxel as the precursor. Albumin-[123I]iodo-paclitaxel nanoparticles ([123I]APNs) were prepared using a desolvation technique. Liposome-encapsulated APNs (L-[123I]APNs) were prepared by thin-film hydration using DSPE-PEG2000, HSPC, and cholesterol. The rats in each group were injected with each test drug into the subserosa of the stomach antrum. After predetermined times (30 min, 2, 4, 8 h, and 24 h), molecular images of nuclear medicine were acquired using single-photon emission computed tomography/computed tomography.Results: Paclitaxel, APNs, and L-APNs showed a high cumulative distribution in the stomach, with L-APNs showing the largest area under the curve. Most drugs administered via the gastric subserosal route are distributed in the stomach and intestines, with a low uptake of less than 1% in other major organs. The time to reach the maximum concentration in the intestine for L-APNs, paclitaxel, and APNs was 6.67, 5.33, and 4.00 h, respectively.Conclusion: These preliminary results imply that L-APNs have the potential to serve as a novel paclitaxel preparation method for the regional treatment of gastric cancer

Telomere dysfunction and cell survival: roles for distinctTIN2-containing complexes

Telomeres are maintained by three DNA binding proteins, TRF1, TRF2 and POT1, and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. These and two other proteins form a soluble complex that may be the core telomere-maintenance complex. It is not clear whether subcomplexes exist or function in vivo. Here, we provide evidence for two TIN2 subcomplexes with distinct functions in human cells. TIN2 ablation by RNA interference caused telomere uncapping and p53-independent cell death in all cells tested. However, we isolated two TIN2 complexes from cell lysates, each selectively sensitive to a TIN2 mutant (TIN2-13, TIN2-15C). In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN215C more than TIN2-13 caused genomic instability and cell death. Thus, TIN2 subcomplexes likely have distinct functions in telomere maintenance, and may provide selective targets for eliminating cells with mutant p53

Factors Influencing Residual Pleural Opacity in Tuberculous Pleural Effusion

Tuberculous pleural effusion (TPE) leads to residual pleural opacity (RPO) in a significant proportion of cases. The aim of this study was to investigate which TPE patients would have RPO following the treatment. This study was performed prospectively for a total of 60 TPE patients, who underwent pleural fluid analysis on the initial visit and chest radiographs and computed tomography (CT) scans before and after the administration of antituberculous medication. At the end of antituberculous medication, the incidence of RPO was 68.3% (41/60) on CT with a range of 2-50 mm. Compared with the non-RPO group, the RPO group had a longer symptom duration and lower pleural fluid glucose level. On initial CT, loculation, extrapleural fat proliferation, increased attenuation of extrapleural fat, and pleura-adjacent atelectasis were more frequent, and parietal pleura was thicker in the RPO group compared with the non-RPO group. By multivariate analysis, extrapleural fat proliferation, loculated effusion, and symptom duration were found to be predictors of RPO in TPE. In conclusion, RPO in TPE may be predicted by the clinico-radiologic parameters related to the chronicity of the effusion, such as symptom duration and extrapleural fat proliferation and loculated effusion on CT

Higher order nuclear organization in growth arrest of human mammary epithelial cells: A novel role for telomere-associated protein TIN2

Summary Nuclear organization, such as the formation of specific nuclear subdomains, is generally thought to be involved in the control of cellular phenotype; however, there are relatively few specific examples of how mammalian nuclei organize during radical changes in phenotype, such as those which occur during differentiation and growth arrest. Using human mammary epithelial cells (HMECs) in which growth arrest is essential for morphological differentiation, we show that the arrest of cell proliferation is accompanied by a reorganization of the telomere-associated protein, TIN2, into one to three large nuclear subdomains. The large TIN2 domains do not contain telomeres and occur concomitant with the continued presence of TIN2 at telomeres. The TIN2 domains were sensitive to DNAse, but not RNAse, occurred frequently, but not exclusively near nucleoli, and overlapped often with dense domains containing heterochromatin protein 1γ

The determinants of stroke phenotypes were different from the predictors (CHADS2 and CHA2DS2-VASc) of stroke in patients with atrial fibrillation: a comprehensive approach

<p>Abstract</p> <p>Background</p> <p>Atrial fibrillation (AF) is a leading cause of fatal ischemic stroke. It was recently reported that international normalized ratio (INR) levels were associated with infarct volumes. However, factors other than INR levels that affect stroke phenotypes are largely unknown. Therefore, we evaluated the determinants of stroke phenotypes (pattern and volume) among patients with AF who were not adequately anticoagulated.</p> <p>Methods</p> <p>We analyzed data pertaining to consecutive AF patients admitted over a 6-year period with acute MCA territory infarcts. We divided the patients according to DWI (diffusion-weighted imaging) lesion volumes and patterns, and the relationship between stroke predictors (the CHADS₂and CHA₂DS₂-VASc score), systemic, and local factors and each stroke phenotype were then evaluated.</p> <p>Results</p> <p>The stroke phenotypes varied among 231 patients (admission INR median 1.06, interquartile range (IQR) 1.00-1.14). Specifically, (1) the DWI lesion volumes ranged from 0.04-338.62 ml (median 11.86 ml; IQR, 3.07-44.20 ml) and (2) 46 patients had a territorial infarct pattern, 118 had a lobar/deep pattern and 67 had a small scattered pattern. Multivariate testing revealed that the CHADS₂and CHA₂DS₂-VASc score were not related to either stroke phenotype. Additionally, the prior use of antiplatelet agents was not related to the stroke phenotypes. Congestive heart failure and diastolic dysfunction were not associated with stroke phenotypes.</p> <p>Conclusions</p> <p>The results of this study indicated that the determinants of stroke phenotypes were different from the predictors (i.e., CHADS2 and CHA₂DS₂-VASc score) of stroke in patients with AF.</p