EXO1-mediated DNA repair by single-strand annealing is essential for BRCA1-deficient cells.

Deficiency for the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR) leads to chromosomal instability and diseases such as cancer. Yet, defective HR also results in vulnerabilities that can be exploited for targeted therapy. Here, we identify such a vulnerability and show that BRCA1-deficient cells are dependent on the long-range end-resection factor EXO1 for survival. EXO1 loss results in DNA replication-induced lesions decorated by poly(ADP-ribose)-chains. In cells that lack both BRCA1 and EXO1, this is accompanied by unresolved DSBs due to impaired single-strand annealing (SSA), a DSB repair process that requires the activity of both proteins. In contrast, BRCA2-deficient cells have increased SSA, also in the absence of EXO1, and hence are not dependent on EXO1 for survival. In agreement with our mechanistic data, BRCA1-mutated tumours have elevated EXO1 expression and contain more genomic signatures of SSA compared to BRCA1-proficient tumours. Collectively, our data indicate that EXO1 is a promising novel target for treatment of BRCA1-deficient tumours.

Transcriptomic profiling identified altered expression of genes associated with testicular functions in adult F1 rats exposed to carbimazole during fetal period.

The central goal of this study was to investigate the alterations in transcriptome of testis in F1 generation adult rats exposed to carbimazole prenatally. At post-natal day 100, the testis of rats delivered to carbimazole exposed (time-mated pregnant rats orally administered with carbimazole from gestation day 9 to 21) and control (untreated pregnant rats) groups were subjected to transcriptomic analysis using NGS platform. A total of 187 differentially expressed (up regulated: 49 genes; down regulated: 138) genes were identified in carbimazole exposed rats over controls and the major processes associated with these altered testicular transcripts were examined. Functional clustering analysis suggest that the involvement of identified DEGs were linked to intrinsic and extrinsic apoptotic pathways, mitochondrial solute carriers slc25a members, nuclear receptors/zinc family members, steroidogenic pathway and cholesterol synthesis, and growth factors and protein kinases and thus represent potential mediators of the developmental toxic effects of carbimazole in F1 generation rats. Based on the findings, it can be concluded that prenatal exposure to carbimazole prominently affects expression of multiple transcripts implicating key regulatory events associated with testicular functions, spermatogenesis and steroidogenesis in rats at their adulthood. These results support our earlier findings and hypothesis. This background information obtained at the testicular transcriptome during gestational hypothyroidism might be helpful for future studies and experiments to gain additional in-depth analysis and to develop strategies to protect F1 generation male reproductive health. SIGNIFICANCE: The rationale for the paper described thyroid gland changes in the off springs. Antithyroid drugs are widely used to control thyroid disorders and used to control thyroid hormone levels during surgeries. Carbimazole is one of the antithyroid drugs and is a parent molecule of methimazole. Both the drugs can able to cross placenta. During fetal period, the development of thyroid gland is not completely formed and hence, the fetus entirely depends on the maternal thyroid hormones. Therefore, it is conceivable that the disturbances at the level of maternal thyroid hormones could interfere with the development of vital organs such as testis and glands including thyroid gland (Kala et al., 2012). To address this notion, the present study was designed and executed.

α-lipoic acid protects testis and epididymis against linuron-induced oxidative toxicity in adult rats.

Linuron is well known for its antiandrogenic property. However, the effects of linuron on testicular and epididymal pro- and antioxidant status are not well defined. On the other hand, α-lipoic acid is well known as universal antioxidant. Therefore, the purpose of this study was twofold: firstly to investigate whether linuron exposure alters antioxidant status in the testis and epididymis of rats and if so, whether the supplementation of α-lipoic acid mitigates linuron-induced oxidative toxicity in rats. To address this question, α-lipoic acid at a dose of 70 mg/Kg body weight (three times a week) was administered to linuron exposed rats (10 or 50 mg/Kg body weight, every alternate day over a period of 60 days), and the selected reproductive endpoints were analyzed after 60 days. Respective controls were maintained in parallel. Linuron at selected doses reduced testicular daily sperm count, and epididymal sperm count, sperm motility, sperm viability, and number of tail coiled sperm, reduced activity levels of 3ß- and 17ß-hydroxysteroid dehydrogenases, decreased expression levels of StAR mRNA, inhibition of testosterone levels, and elevated levels of testicular cholesterol in rats over controls. Linuron intoxication deteriorated the structural integrity of testis and epididymis associated with reduced the reproductive performance over controls. Conversely, α-lipoic acid supplementation enhanced sperm quality and improved the testosterone synthesis pathway in linuron exposed rats over its respective control. Administration of α-lipoic acid restored inhibition of testicular and epididymal enzymatic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidise) and non-enzymatic (glutathione content), increased lipid peroxidation and protein carbonyl content produced by linuron in rats. α-lipoic acid supplementation inhibited the expression levels of testicular caspase-3 mRNA levels and also its activity in linuron treated rats. To summate, α-lipoic acid-induced protection of reproductive health in linuron treated rats could be attributed to its antioxidant, and steroidogenic properties.

α-lipoic acid inhibits oxidative stress in testis and attenuates testicular toxicity in rats exposed to carbimazole during embryonic period.

The aim of this study was to evaluate the probable protective effect of α-lipoic acid against testicular toxicity in rats exposed to carbimazole during the embryonic period. Time-mated pregnant rats were exposed to carbimazole from the embryonic days 9-21. After completion of the gestation period, all the rats were allowed to deliver pups and weaned. At postnatal day 100, F1 male pups were assessed for the selected reproductive endpoints. Gestational exposure to carbimazole decreased the reproductive organ indices, testicular daily sperm count, epididymal sperm variables viz., sperm count, viable sperm, motile sperm and HOS-tail coiled sperms. Significant decrease in the activity levels of 3ß- and 17ß-hydroxysteroid dehydrogenases and expression of StAR mRNA levels with a significant increase in the total cholesterol levels were observed in the testis of experimental rats over the controls. These events were also accompanied by a significant reduction in the serum testosterone levels in CBZ exposed rats, indicating reduced steroidogenesis. In addition, the deterioration of the testicular architecture and reduced fertility ability were noticed in the carbimazole exposed rats. Significant reduction in the activity levels of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and reduced glutathione content with a significant increase in the levels of lipid peroxidation were observed in the testis of carbimazole exposed rats over the controls. Conversely, supplementation of α-lipoic acid (70 mg/Kg bodyweight) ameliorated the male reproductive health in rats exposed to carbimazole during the embryonic period as evidenced by enhanced reproductive organ weights, selected sperm variables, testicular steroidogenesis, and testicular enzymatic and non-enzymatic antioxidants. To conclude, diminished testicular antioxidant balance associated with reduced spermatogenesis and steroidogenesis might be responsible for the suppressed reproduction in rats exposed to the carbimazole transplacentally. On the other hand, α-lipoic acid through its antioxidant and steroidogenic properties mitigated testicular toxicity which eventually restored the male reproductive health of carbimazole-exposed rats.

RPA-1 from Leishmania amazonensis (LaRPA-1) structurally differs from other eukaryote RPA-1 and interacts with telomeric DNA via its N-terminal OB-fold domain.

Replication protein A-1 (RPA-1) is a single-stranded DNA-binding protein involved in DNA metabolism. We previously demonstrated the interaction between LaRPA-1 and telomeric DNA. Here, we expressed and purified truncated mutants of LaRPA-1 and used circular dichroism measurements and molecular dynamics simulations to demonstrate that the tertiary structure of LaRPA-1 differs from human and yeast RPA-1. LaRPA-1 interacts with telomeric ssDNA via its N-terminal OB-fold domain, whereas RPA from higher eukaryotes show different binding modes to ssDNA. Our results show that LaRPA-1 is evolutionary distinct from other RPA-1 proteins and can potentially be used for targeting trypanosomatid telomeres.

The effect of primary cytoreduction on outcomes of patients with FIGO stage IIIC ovarian cancer stratified by the initial tumor burden in the upper abdomen cephalad to the greater omentum.

OBJECTIVE: Our objective was to analyze the effect of surgical outcome on progression-free survival (PFS) and overall survival (OS) of patients with advanced ovarian carcinoma stratified by the initial presence and volume of upper abdominal disease cephalad to the greater omentum (UAD) found at the time of exploration. METHODS: We evaluated all patients with FIGO stage IIIC ovarian carcinoma who underwent primary cytoreduction followed by platinum-based chemotherapy at our institution between January 1989 and December 2006. The effect of surgical outcome was investigated using a time-to-event analysis. A Cox proportional hazards model was fit using clinical, surgical, and postoperative variables. RESULTS: We identified 526 evaluable patients. Optimal versus suboptimal cytoreduction was significantly associated with improved median PFS and OS in patients with no, minimal (1 cm) UAD. On multivariate analysis, patients with bulky UAD who underwent optimal cytoreduction had a 28% decreased risk of relapse (hazard ratio, 0.72; 95% confidence interval: 0.53-0.99; P=0.04) and a 33% decreased risk of death (hazard ratio, 0.67; 95% confidence interval: 0.47-0.96; P=0.03) compared to patients who underwent suboptimal cytoreduction. CONCLUSION: The presence of large-volume disease found during surgical exploration does not preclude the benefit of optimal cytoreduction. The findings support the management strategy of maximizing surgical efforts with increasing tumor burden in patients with stage IIIC ovarian cancer. Prospective studies are needed to more precisely quantify tumor burden and accurately determine the specific impact of cytoreduction on outcome.

Increased frequency of abnormal Papanicolaou smears in adolescents.

Abnormal Papanicolaou smears has increased in adolescents. Our objective was to analyze the frequency of cervical intraepithelial neoplasia (CIN) in adolescents (< 20 years of age) over the last 12 years, comparing to adult (> or = 20 years of age). We studied 110,283 (10.85% of adolescents) reports from Papanicolaou smears between 1987 and 1999 in a public university hospital that has a screening program for cervical cancer prevention. The tests were divided into 3 periods (1987-1991, 1992-1995 and 1996-1999) for studying the evolution of frequencies. CIN I was more frequent among adolescents (1.73% vs. 0.99%) and CIN III and invasive cancer among adult women (0.62% vs. 0.05%, and 0.39% vs. 0.0083%, respectively). Between the periods 1987-1991 and 1996-1999 there was an increased in the frequency of CIN I among adolescents (from 0.78-2.17%) and adults (from 0.72-1.16%); CIN II decreased among adult patients (from 0.52-0.28%) and tripled among adolescents over recent years (from 0.15-0.47%), and CIN III increased in both group, although without statistical significance. One case of invasive carcinoma among adolescents occurred in the period from 1996-1999. We strongly recommend the inclusion of adolescent populations in the screening programs, from the time that they begin sexual activity.