A Comparative Study on the Lysosomal Cation Channel TMEM175 Using Automated Whole-Cell Patch-Clamp, Lysosomal Patch-Clamp, and Solid Supported Membrane-Based Electrophysiology: Functional Characterization and High-Throughput Screening Assay Development.

The lysosomal cation channel TMEM175 is a Parkinson's disease-related protein and a promising drug target. Unlike whole-cell automated patch-clamp (APC), lysosomal patch-clamp (LPC) facilitates physiological conditions, but is not yet suitable for high-throughput screening (HTS) applications. Here, we apply solid supported membrane-based electrophysiology (SSME), which enables both direct access to lysosomes and high-throughput electrophysiological recordings. In SSME, ion translocation mediated by TMEM175 is stimulated using a concentration gradient at a resting potential of 0 mV. The concentration-dependent K+ response exhibited an I/c curve with two distinct slopes, indicating the existence of two conducting states. We measured H+ fluxes with a permeability ratio of PH/PK = 48,500, which matches literature findings from patch-clamp studies, validating the SSME approach. Additionally, TMEM175 displayed a high pH dependence. Decreasing cytosolic pH inhibited both K+ and H+ conductivity of TMEM175. Conversely, lysosomal pH and pH gradients did not have major effects on TMEM175. Finally, we developed HTS assays for drug screening and evaluated tool compounds (4-AP, Zn as inhibitors; DCPIB, arachidonic acid, SC-79 as enhancers) using SSME and APC. Additionally, we recorded EC50 data for eight blinded TMEM175 enhancers and compared the results across all three assay technologies, including LPC, discussing their advantages and disadvantages.

Robust genomic copy number predictor of pan cancer metastasis.

Copy number alterations(CNAs) are the most common genetic changes observed in many cancers, reflecting the innate chromosomal instability of this disorder. Yet, how these alterations affect gene function to promote metastases across different tumor types has not been established. In this study, we developed a pan-cancer metastasis potential score (panMPS) based on observed CNAs. panMPS predicts metastasis and metastasis-free survival in cohorts of patients with prostate cancer, triple negative breast cancer and lung adenocarcinoma, and overall survival in the Metabric breast cancer cohort and three cohorts from The Cancer Genome Atlas (TCGA), including prostate, breast and lung adenocarcinoma. These CNAs are present in cell lines of metastatic tumors from eight different origins, reflected by an elevated panMPS for all cell lines. Many copy number alterations involve large chromosomal segments that encompass multiple genes ("clumps"). We show that harnessing this structural information to select only one gene per clump captures the contributions of other genes within the clump, resulting in a robust predictor of metastasis outcome. These sets of selected genes are distinct from cancer drivers that undergo mutation, and in fact, metastasis-related functions have been published for over half of them.

Utilization of the 21-Gene Recurrence Score in a Diverse Breast Cancer Patient Population: Development of a Clinicopathologic Model to Predict High-Risk Scores and Response to Neoadjuvant Chemotherapy.

INTRODUCTION: The 21-gene expression profile [Oncotype DX Recurrence Score (RS)] stratifies benefit from adjuvant chemotherapy in hormone receptor (HR)-positive, HER2/neu-negative, node-negative breast cancer. It is not routinely applied to predict neoadjuvant chemotherapy (NACT) response; data in diverse patient populations also are limited. We developed a statistical model based on standard clinicopathologic features to identify high-risk cases (RS > 30) and then evaluated ability of predicted high RS to predict for NACT downstaging. METHODS: Primary surgery patients with Oncotype DX RS testing 2012-2016 were identified from a prospectively-maintained database. A RS predictive model was created and applied to a dataset of comparable NACT patients. Response was defined as tumor size decrease ≥ 1 cm. RESULTS: Of 394 primary surgery patients-60.4% white American; 31.0% African American-RS distribution was similar for both groups. No single feature reliably identified high RS patients; however, a model accounting for age, HR expression, proliferative index (MIB1/Ki67), histology, and tumor size was generated, with receiver operator area under the curve 0.909. Fifty-six NACT patients were identified (25 African American). Of 21 cases with all relevant clinicopathology, 14 responded to NACT and the model generated high-risk RS in 14 (100%); conversely, of 16 cases generating high-risk RS, only 2 did not respond. CONCLUSIONS: Predictive modelling can identify high RS patients; this model also can identify patients likely to experience primary tumor downstaging with NACT. Until this model is validated in other datasets, we recommend that Oncotype-eligible patients undergo primary surgery with decisions regarding chemotherapy made in the adjuvant setting.

Scarless and site-directed mutagenesis in Salmonella enteritidis chromosome.

BACKGROUND: A variety of techniques have been described which introduce scarless, site-specific chromosomal mutations. These techniques can be applied to make point mutations or gene deletions as well as insert heterologous DNA into bacterial vectors for vaccine development. Most methods use a multi-step approach that requires cloning and/or designing repeat sequences to facilitate homologous recombination. We have modified previously published techniques to develop a simple, efficient PCR-based method for scarless insertion of DNA into Salmonella enteritidis chromosome. RESULTS: The final product of this mutation strategy is the insertion of DNA encoding a foreign epitope into the S. enteritidis genome without the addition of any unwanted sequence. This experiment was performed by a two-step mutation process via PCR fragments, Red recombinase and counter-selection with the I-SceI enzyme site. First, the I-SceI site and kanamycin resistance gene were introduced into the genome of cells expressing Red recombinase enzymes. Next, this sequence was replaced by a chosen insertion sequence. DNA fragments used for recombination were linear PCR products which consisted of the foreign insertion sequence flanked by homologous sequences of the target gene. Described herein is the insertion of a section of the M2e epitope (LM2) of Influenza A virus, a domain of CD154 (CD154s) or a combination of both into the outer membrane protein LamB of S. enteritidis. CONCLUSION: We have successfully used this method to produce multiple mutants with no antibiotic gene on the genome or extra sequence except those nucleotides required for expression of epitope regions. This method is advantageous over other protocols in that it does not require cloning or creating extra duplicate regions to facilitate homologous recombination, contains a universal construct in which an epitope of choice can be placed to check for cell surface expression, and shows high efficiency when screening for positive mutants. Other opportunities of this mutational strategy include creating attenuated mutants and site-specific, chromosomal deletion mutations. Furthermore, this method should be applicable in other gram-negative bacterial species where Red recombinase enzymes can be functionally expressed.

An open-label study of adjunctive modafinil in patients with sedation related to serotonergic antidepressant therapy.

OBJECTIVE: In patients with major depressive disorder (MDD), excessive sleepiness and fatigue not only are major components of the disorder, but also may occur as side effects of antidepressant therapy. In addition, sedation may be a consequence of antidepressant regimens. The novel wake-promoting agent modafinil improves wakefulness and reduces fatigue across a variety of clinical disorders. This study assessed the use of modafinil as an adjunctive treatment in patients with MDD who reported sedation related to serotonergic antidepressant therapy. METHOD: Data were collected between September 2001 and December 2003. Twenty men and women with DSM-IV-defined MDD were enrolled in this 3-week, open-label, single-center study. In addition to ongoing and stable treatment with selective serotonin reuptake inhibitors (SSRIs), clinic patients received modafinil once daily. Efficacy assessments were conducted at 1-week intervals. RESULTS: Sixteen patients (80%) completed the study. Modafinil plus SSRIs significantly improved overall depressive symptoms, as shown by reductions in mean Hamilton Rating Scale for Depression total scores (p <.001 vs. baseline). Adjunctive modafinil significantly improved subjective estimates of wakefulness on the Epworth Sleepiness Scale (p <.001, all weeks) and reduced fatigue on the Fatigue Severity Scale (p =.009). At the final visit, modafinil had improved overall health status and health-related quality of life, as shown by significant improvements in mean Medical Outcomes Study Short-Form 12-Item Health Survey total scores (p =.007) and in physical health (p =.04) and mental health (p =.006) subscores. CONCLUSION: In patients with MDD who experience sedation as a side effect of antidepressant therapy, adjunctive modafinil improved wakefulness and reduced fatigue. Modafinil plus SSRIs also improved mood and quality of life.