Enhanced Cerebroprotection of Xenon-Loaded Liposomes in Combination with rtPA Thrombolysis for Embolic Ischemic Stroke

Xenon (Xe) has shown great potential as a stroke treatment due to its exceptional ability to protect brain tissue without inducing side effects. We have previously developed Xe-loaded liposomes for the ultrasound-activated delivery of Xe into the cerebral region and demonstrated their therapeutic efficacy. At present, the sole FDA-approved thrombolytic agent for stroke treatment is recombinant tissue plasminogen activator (rtPA). In this study, we aimed to investigate the potential of combining Xe-liposomes with an intravenous rtPA treatment in a clinically relevant embolic rat stroke model. We evaluated the combinational effect using an in vitro clot lysis model and an in vivo embolic middle cerebral artery occlusion (eMCAO) rat model. The treatment groups received intravenous administration of Xe-liposomes (20 mg/kg) at 2 h post-stroke onset, followed by the administration of rtPA (10 mg/kg) at either 2 or 4 h after the onset. Three days after the stroke, behavioral tests were conducted, and brain sections were collected for triphenyltetrazolium chloride (TTC) and TUNEL staining. Infarct size was determined as normalized infarct volume (%). Both in vitro and in vivo clot lysis experiments demonstrated that Xe-liposomes in combination with rtPA resulted in effective clot lysis comparable to the treatment with free rtPA alone. Animals treated with Xe-liposomes in combination with rtPA showed reduced TUNEL-positive cells and demonstrated improved neurological recovery. Importantly, Xe-liposomes in combination with late rtPA treatment reduced rtPA-induced hemorrhage, attributing to the reduction of MMP9 immunoreactivity. This study demonstrates that the combined therapy of Xe-liposomes and rtPA provides enhanced therapeutic efficacy, leading to decreased neuronal cell death and a potential to mitigate hemorrhagic side effects associated with late rtPA treatment.

Epigenetic Forensics for Suspect Identification and Age Prediction

Background: Genetic testing at crime scenes is an instrumental molecular technique to identify or eliminate suspects, as well as to overturn wrongful convictions. Yet, genotyping alone cannot reveal the age of a sample, which could help advance the utility of crime scene samples for suspect identification. The distribution of cytosine methylation within a DNA sample can be leveraged to determine the epigenetic age of someone's blood. Methodology: We sought to demonstrate the ability of DNA methylation markers to accurately discern the age of blood spots from an actual crime scene, a "mock" crime scene, and also from a tube of blood stored in ethylenediaminetetraacetic acid for >20 years. This was achieved by quantifying methylation within known age-associated genetic loci across each DNA sample. We observed a strong linear coefficient (0.91) and high overall correlation (R ² = 0.963) between the known age of a sample and the predicted age. Conclusion: We show that novel methods for targeted methylation and low-input whole-genome bisulfite sequencing can enable a novel and improved forensic profile of a crime scene that discerns not only who was present at the crime, but also their age. Finally, we use this model to discern the age and provenance of a blood sample that was used in a criminal investigation.

Abstract 828: Accelerated epigenetic aging in bladder cancer patients

Aging represents the most important risk factor for many chronic diseases including cardiovascular diseases, diabetes, and cancer, therefore understanding the mechanisms of aging is a fundamental step for designing new treatments for chronic diseases. DNA methylation is the most reliable and accurate molecular marker for aging quantification, however, genome-wide DNA methylation profiling techniques, such as reduced representative bisulfite sequencing and Illumina Bead Array that are widely used in aging research are prohibitively expensive and have poor data quality at low-read coverage sites. Here we report a robust targeted bisulfite sequencing approach, called SWARM® (Simplified Whole-panel Amplification Reaction Method), for the accurate biological age determination. SWARM™ is flexible and low cost, requires relatively low DNA starting material, allows the simultaneous amplification and sequencing of hundreds of loci, and has shown to increase sample throughput. Using the SWARM® approach, we were able to analyze the methylation level of several hundreds of age-associated loci including the published Horvath Clock sites. Gender-specific age-predictive models were built using the elastic net regression of DNA methylation levels of the loci and chronological age of urine DNA samples of over 300 healthy subjects of 18 to 88 years old. Urine samples from bladder cancer patients exhibit significant age acceleration, with an average of >10 years. In brief, our gender-specific urine DNAge® analysis is a tool for the precise biological aging quantification and can be used to address questions in aging and urinary track cancers.

Citation Format: Yap Ching Chew, Wei Guo, Xiaojing Yang, Paolo Piatti, Mingda Jin, Keith Booher, Benjamin Jara, Xi-Yu Jia. Accelerated epigenetic aging in bladder cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 828.

Isogenic mice exhibit sexually-dimorphic DNA methylation patterns across multiple tissues

Background

Cytosine methylation is a stable epigenetic modification of DNA that plays an important role in both normal physiology and disease. Most diseases exhibit some degree of sexual dimorphism, but the extent to which epigenetic states are influenced by sex is understudied and poorly understood. To address this deficit we studied DNA methylation patterns across multiple reduced representation bisulphite sequencing datasets (from liver, heart, brain, muscle and spleen) derived from isogenic male and female mice.

Results

DNA methylation patterns varied significantly from tissue to tissue, as expected, but they also varied between the sexes, with thousands of sexually dimorphic loci identified. The loci affected were largely autonomous to each tissue, even within tissues derived from the same germ layer. At most loci, differences between genders were driven by females exhibiting hypermethylation relative to males; a proportion of these differences were independent of the presence of testosterone in males. Loci harbouring gender differences were clustered in ontologies related to tissue function.

Conclusions

Our findings suggest that gender is underwritten in the epigenome in a tissue-specific and potentially sex hormone-independent manner. Gender-specific epigenetic states are likely to have important implications for understanding sexually dimorphic phenotypes in health and disease.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12864-017-4350-x) contains supplementary material, which is available to authorized users.

Downregulation of Cdc6 and pre-replication complexes in response to methionine stress in breast cancer cells

Methionine and homocysteine are metabolites in the transmethylation pathway leading to synthesis of the methyl-donor S-adenosylmethionine (SAM). Most cancer cells stop proliferating during methionine stress conditions, when methionine is replaced in the growth media by its immediate metabolic precursor homocysteine (Met-Hcy+). Non-transformed cells proliferate in Met-Hcy+ media, making the methionine metabolic requirement of cancer cells an attractive target for therapy, yet there is relatively little known about the molecular mechanisms governing the methionine stress response in cancer cells. To study this phenomenon in breast cancer cells, we selected methionine-independent-resistant cell lines derived from MDAMB468 breast cancer cells. Resistant cells grew normally in Met-Hcy+ media, whereas their parental MDAMB468 cells rapidly arrest in the G 1 phase. Remarkably, supplementing Met-Hcy+ growth media with S-adenosylmethionine suppressed the cell proliferation defects, indicating that methionine stress is a consequence of SAM limitation rather than low amino acid concentrations. Accordingly, mTORC1 activity, the primary effector responding to amino acid limitation, remained high. However, we found that levels of the replication factor Cdc6 decreased and pre-replication complexes were destabilized in methionine-stressed MDAMB468 but not resistant cells. Our study characterizes metabolite requirements and cell cycle responses that occur during methionine stress in breast cancer cells and helps explain the metabolic uniqueness of cancer cells.

Localization of proteins and organelles using fluorescence microscopy

This chapter describes the different methods used for localization of proteins and organelles in Pichia pastoris. A series of plasmids and a modified immunofluorescence protocol for localization and co-localization of proteins and organelles are described. Also included are protocols for the labeling of different subcellular organelles with vital stains.

The use of flow cytometry for the prognosis of stage II adjuvant treated breast cancer patients

Characterization of breast cancer cells by histology, flow cytometry, and steroid receptors was performed on 197 Stage II breast node positive cancer patients given adjuvant chemotherapy, plus tamoxifen for patients with positive hormone receptors. Histologic and steroid receptor assays were performed using standard techniques; flow cytometric analysis was performed from paraffin-embedded blocks obtained from the primary tumor. Quality control studies on reproducibility, tissue heterogeneity, and analysis procedures have been included. Of the 197 patients studied, aneuploidy was found in 102 (52%); the median %S value was 8% with a range of 0.4% to 38%. Our results demonstrated that number of positive nodes, receptor status, and grade were of prognostic value. Cell cycle kinetic data were not of independent prognostic value in this series. However, ploidy could differentiate in prognosis in the receptor-negative subgroup. Patients with receptor-negative tumors had a significantly better overall survival if the tumor was diploid in nature. Cell kinetics was not significantly prognostic for either receptor subgroup, although patients with higher %S tended to have better relapse-free and overall survival. This is in disagreement with other studies and may demonstrate that treatment has confounded our results and diminished the ability of flow cytometry data to help predict outcome.