Publications by authors named "Michael T Barrett"

Article Synopsis
  • Archived tissues, particularly frozen and FFPE samples, are valuable for high-definition genomics aimed at personalized cancer treatment, but face challenges like low cell yields and DNA quality issues due to degradation and contamination.
  • Recent advancements in single cell DNA sequencing (scDNA-seq) allow for better study of tumor heterogeneity and subclonal populations, essential for understanding tumor development and resistance to therapies.
  • The research presented optimized methods for isolating intact nuclei from fresh frozen and FFPE tissues, validated through a sequencing panel, which could enhance the utility of these archived samples in cancer research and clinical applications.
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Although colorectal cancer (CRC) remains the second leading cause of cancer-related death in the United States, the overall incidence and mortality from the disease have declined in recent decades. In contrast, there has been a steady increase in the incidence of CRC in individuals under 50 years of age. Hereditary syndromes contribute disproportionately to early onset CRC (EOCRC).

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  • Metastatic castration-resistant prostate cancer (mCRPC) is a severe form of cancer that often leads to poor patient outcomes, prompting the need for better treatment options.
  • Researchers developed and characterized three new patient-derived tumor xenograft (PDTX) models to explore the effectiveness of combining CDK4/6 inhibitors with AKT inhibitors, using 3D spheroids to study drug resistance patterns.
  • Findings indicated that the combination therapy showed promising results in overcoming resistance to single-agent treatments, which supports future clinical trials for mCRPC patients with specific genetic profiles.
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  • Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer that requires new treatment options, prompting research into its underlying mechanisms.
  • The study reveals a significant role of super-enhancers in regulating a cascade of RNA-binding proteins that enhance mRNA translation, promoting PDAC growth.
  • Targeting this cascade, specifically the protein arginine methyltransferase 1 (PRMT1), shows potential as a therapeutic strategy, particularly in Myc-high PDAC patients, leading to reduced tumor growth in experimental models.
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The physical structure and dynamics of cells are supported by micron-scale actin networks with diverse geometries, protein compositions, and mechanical properties. These networks are composed of actin filaments and numerous actin binding proteins (ABPs), many of which engage multiple filaments simultaneously to crosslink them into specific functional architectures. Mechanical force has been shown to modulate the interactions between several ABPs and individual actin filaments, but it is unclear how this phenomenon contributes to the emergent force-responsive functional dynamics of actin networks.

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This work examines differences in chromatin accessibility, methylation, and response to DNA hypomethylating agents between mismatch repair-deficient and non-mismatch repair-deficient endometrial cancer. Next-generation sequencing of a stage 1B, grade 2 endometrioid endometrial cancer tumor revealed microsatellite instability and a variant of unknown significance in along with global and hypermethylation. Inhibition of viability by decitabine in the study and comparison tumors was minimal, as shown by an inhibitory effect of 0 and 17.

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Article Synopsis
  • Vesiculoviruses are promising candidates for cancer treatment due to their rapid replication and ability to target tumors effectively while avoiding immune system detection.
  • Researchers developed a synthetic chimeric virus called VMG, which combines elements from Morreton virus and vesicular stomatitis virus, and found it effectively induced cell death in various sarcoma types across different species.
  • Initial safety tests in healthy mice showed no toxicity, and while VMG didn't suppress tumors in one model, it successfully stimulated immune responses, showing potential as a new oncolytic virotherapy for sarcoma.
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Amplification of chromosome 9p24.1 targeting PD-L1, PD-L2, and JAK2 (PDJ amplicon) is present in subsets of triple negative breast cancers (TNBCs) and is associated with poor clinical outcomes. However, the prevalence of PDJ+ TNBCs varies extensively across studies applying different methods for interrogating samples of interest.

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  • Researchers are studying patient-derived organoids (PDOs) to see if they can help predict how patients with gastrointestinal (GI) cancers will react to treatments.
  • They created PDOs from cancer samples and found that about 80% of the time, the PDO responses matched the actual responses of the patients.
  • The type of culture media used for growing the PDOs can change how they respond to treatments, which is important for choosing the right therapy for patients with GI cancers.
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Background: Morreton virus (MORV) is an oncolytic Vesiculovirus , genetically distinct from vesicular stomatitis virus (VSV).

Aim: To report that MORV induced potent cytopathic effects (CPEs) in cholangiocarcinoma (CCA) and hepatocellular carcinoma (HCC) in vitro models.

Approach And Results: In preliminary safety analyses, high intranasal doses (up to 10 10 50% tissue culture infectious dose [TCID 50 ]) of MORV were not associated with significant adverse effects in immune competent, non-tumor-bearing mice.

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Epstein-Barr virus (EBV)-positive extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphomas) were initially described in solid organ transplant recipients, and, more recently, in other immunodeficiency settings. The overall prevalence of EBV-positive MALT lymphomas has not been established, and little is known with respect to their genomic characteristics. Eight EBV-positive MALT lymphomas were identified, including 1 case found after screening a series of 88 consecutive MALT lymphomas with EBER in situ hybridization (1%).

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Background And Aims: Biliary tract cancers (BTCs) are uncommon, but highly lethal, gastrointestinal malignancies. Gemcitabine/cisplatin is a standard-of-care systemic therapy, but has a modest impact on survival and harbors toxicities, including myelosuppression, nephropathy, neuropathy, and ototoxicity. Whereas BTCs are characterized by aberrations activating the cyclinD1/cyclin-dependent kinase (CDK)4/6/CDK inhibitor 2a/retinoblastoma pathway, clinical use of CDK4/6 inhibitors as monotherapy is limited by lack of validated biomarkers, diffident preclinical efficacy, and development of acquired drug resistance.

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Breast cancers exhibit intratumoral heterogeneity associated with disease progression and therapeutic resistance. To define the sources and the extent of heterogeneity, we performed an in-depth analysis of the genomic architecture of three chemoradiation-naïve breast cancers with well-defined clinical features including variable ER, PR, ERBB2 receptor expression and two distinct pathogenic BRCA2 genotypes. The latter included a germ line carrier and a patient with a somatic variant.

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Adenosquamous cancer of the pancreas (ASCP) is a subtype of pancreatic cancer that has a worse prognosis and greater metastatic potential than the more common pancreatic ductal adenocarcinoma (PDAC) subtype. To distinguish the genomic landscape of ASCP and identify actionable targets for this lethal cancer, we applied DNA content flow cytometry to a series of 15 tumor samples including five patient-derived xenografts (PDX). We interrogated purified sorted tumor fractions from these samples with whole-genome copy-number variant (CNV), whole-exome sequencing, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) analyses.

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Lynch syndrome (LS) arises in patients with pathogenic germline variants in DNA mismatch repair genes. LS is the most common inherited cancer predisposition condition and confers an elevated lifetime risk of multiple cancers notably colorectal and endometrial carcinomas. A distinguishing feature of LS associated tumors is accumulation of variants targeting microsatellite repeats and the potential for high tumor specific neoepitope levels.

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Article Synopsis
  • NUC1031 is a new pro-drug designed to improve outcomes in biliary tract cancer (BTC) by addressing resistance mechanisms associated with the standard treatment gemcitabine.
  • Comprehensive testing showed that NUC1031 was less effective than gemcitabine in both lab and animal models, with no additional benefits when combined with cisplatin.
  • Findings indicate that NUC1031 did not perform better than gemcitabine, suggesting the need for a cautious approach to its ongoing clinical trials comparing the two treatments.
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  • The study focused on the effectiveness of a combination treatment of nab-paclitaxel, gemcitabine, and cisplatin in 25 patients with metastatic pancreatic ductal adenocarcinoma, given its DNA repair deficiencies and potential sensitivity to DNA-damaging agents.
  • Conducted from December 2013 to January 2018, the clinical trial assessed patient responses based on established measurement criteria, with a primary focus on complete response rates and safety profiles.
  • Results showed that the treatment had significant side effects, with many patients experiencing severe adverse events, and 12% of participants had fatal outcomes related to the treatment.
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Diffuse large B-cell lymphoma (DLBCL) is up to 17-fold more likely to occur, follows a more aggressive clinical course and frequently presents at advanced stages in HIV infected (+) individuals compared to HIV negative (-) individuals. However, the molecular pathology underpinning the clinical features of DLBCL in HIV(+) patients relative to the general population is poorly understood. We performed a retrospective study examining the transcriptional, genomic and protein expression differences between HIV(+) and HIV(-) germinal center B-cell (GCB) DLBCL cases using digital gene expression analysis, array comparative genomic hybridization (CGH) and immunohistochemistry (IHC).

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Testicular germ cell tumors (TGCTs) are unique amongst solid tumors in terms of the high cure rates using chemotherapy for metastatic disease. Nevertheless, TGCTs still kill approximately 400 men per year, at a median age of 30 years, in the United States. This young age of mortality dramatically amplifies the impact of these deaths for the patients and their often young families.

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Variable tumor cellularity can limit sensitivity and precision in comparative genomics because differences in tumor content can result in misclassifying truncal mutations as region-specific private mutations in stroma-rich regions, especially when studying tissue specimens of mediocre tumor cellularity such as lung adenocarcinomas (LUADs). To address this issue, we refined a nuclei flow-sorting approach by sorting nuclei based on ploidy and the LUAD lineage marker thyroid transcription factor 1 and applied this method to investigate genome-wide somatic copy number aberrations (SCNAs) and mutations of 409 cancer genes in 39 tumor populations obtained from 16 primary tumors and 21 matched metastases. This approach increased the mean tumor purity from 54% (range 7-89%) of unsorted material to 92% (range 79-99%) after sorting.

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Article Synopsis
  • Elevated PD-L1 expression in triple-negative breast cancers (TNBCs) is linked to various genomic features, indicating a potential adaptive immune response and interest in developing predictive immunotherapy biomarkers.
  • Whole tissue samples from 55 resected TNBCs were analyzed for PD-1 and PD-L1 expression, alongside genomic profiling through CNV mapping and whole exome sequencing to gain insights into the tumor genetics.
  • PD-L1 was found on tumor cells in over half of the cases examined, and its presence correlated with improved overall survival, though certain genomic alterations like PTEN deletion didn’t necessarily increase PD-L1 expression.
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Background: Activation of the JAK/STAT pathway is common in triple-negative breast cancer (TNBC) and affects the expression of genes controlling immune signaling. A subset of TNBC cases will have somatic amplification of chromosome 9p24.1, encoding PD-L1, PD-L2, and JAK2, which has been associated with decreased survival.

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Understanding the evolutionary mechanisms and genomic events leading to castration-resistant (CR) prostate cancer (PC) is key to improve the outcome of this otherwise deadly disease. Here, we delineated the tumour history of seven patients progressing to castration resistance by analysing matched prostate cancer tissues before and after castration. We performed genomic profiling of DNA content-based flow-sorted populations in order to define the different evolutionary patterns.

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Background: The choice of a regimen in metastatic pancreatic cancer patients following progression on 1st line therapy is empiric and outcomes are unsatisfactory. This phase II study was performed to evaluate the efficacy of therapy selected by immunohistochemistry (IHC) in these patients following progression after one or more therapies.

Methods: Eligible patients underwent a percutaneous biopsy of a metastatic lesion and treatment selection was determined by IHC.

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ROCK, or Rho-associated coiled coil-containing protein kinase, is a member of the AGC kinase family and has been shown to play a role in cell migration, ECM synthesis, stress-fiber assembly, and cell contraction. Increased ROCK expression has been reported in multiple pathological conditions, including cancer. Here, we report increased expression of ROCK 1 in pancreatic tumor epithelial cells as well as in cancer associated fibroblasts (CAF).

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