The Role of the PAX8/PPARγ Fusion Oncogene in Thyroid Cancer

Thyroid cancer is uncommon and exhibits relatively low mortality rates. However, a subset of patients experience inexorable growth, metastatic spread, and mortality. Unfortunately, for these patients, there have been few significant advances in treatment during the last 50 years. While substantial advances have been made in recent years about the molecular genetic events underlying papillary thyroid cancer, the more aggressive follicular thyroid cancer remains poorly understood. The recent discovery of the PAX8/PPARγ translocation in follicular thyroid carcinoma has promoted progress in the role of PPARγ as a tumor suppressor and potential therapeutic target. The PAX8/PPARγ fusion gene appears to be an oncogene. It is most often expressed in follicular carcinomas and exerts a dominant-negative effect on wild-type PPARγ, and stimulates transcription of PAX8-responsive promoters. PPARγ agonists have shown promising results in vitro, although very few studies have been conducted to assess the clinical impact of these agents

Technical and Regulatory Considerations for Taking Liquid Biopsy to the Clinic: Validation of the JAX PlasmaMonitor

The standard of care in oncology has been genomic profiling of tumor tissue biopsies for the treatment and management of disease, which can prove to be quite challenging in terms of cost, invasiveness of procedure, and potential risk for the patient. As the number of available drugs in oncology continues to increase, so too does the demand for technologies and testing applications that can identify genomic alterations targetable by these new therapies. Liquid biopsies that use a blood draw from the diseased patient may offset the many disadvantages of the invasive procedure. However, as with any new technology or finding in the clinical field, the clinical utility of an analytical test such as that of the liquid biopsy has to be established. Here, we review the clinical testing space for liquid biopsy offerings and elucidate the technical and regulatory considerations to develop such an assay, using our recently validated PlasmaMonito

Genomic Profiling of Two Histologically Distinct Rare Urothelial Cancers in a Clinical Setting to Identify Potential Therapeutic Options for Treatment and Management of Disease.

Molecular profiling of urothelial cancers for therapeutic and prognostic potential has been very limited due to the absence of cancer-specific targeted therapies. We describe here 2 clinical cases with a histological diagnosis of an invasive sarcomatoid and a poorly differentiated carcinoma favoring urothelial with some neuroendocrine differentiation, two of the rarer types of urothelial cancers, which were evaluated for mutations in 212 genes for single-nucleotide variants and copy-number variants and 53 genes for fusions associated with solid tumors. In both cases, we identified variants in 2 genes, Case Rep Oncol 2018 Mar 27; 11(1):196-205

The notch regulator MAML1 interacts with p53 and functions as a coactivator.

Members of the evolutionarily conserved Mastermind (MAM) protein family, including the three related mammalian Mastermind-like (MAML) proteins MAML1-3, function as crucial coactivators of Notch-mediated transcriptional activation. Given the recent evidence of cross-talk between the p53 and Notch signal transduction pathways, we have investigated whether MAML1 may also be a transcriptional coactivator of p53. Indeed, we show here that MAML1 is able to interact with p53. We show that MAML1-p53 interaction involves the N-terminal region of MAML1 and the DNA-binding domain of p53, and we use a chromatin immunoprecipitation assay to show that MAML1 is part of the activator complex that binds to native p53-response elements within the promoter of the p53 target genes. Overexpression of wild-type MAML1 as well as a mutant, defective in Notch signaling, enhanced the p53-dependent gene induction in mammalian cells, whereas MAML1 knockdown reduced the p53-dependent gene expression. MAML1 increases the half-life of p53 protein and enhances its phosphorylation/acetylation upon DNA damage of cells. Finally, RNA interference-mediated knockdown of the single Caenorhabditis elegans MAML homolog, Lag-3, led to substantial abrogation of p53-mediated germ-cell apoptotic response to DNA damage and markedly reduced the expression of Ced-13 and Egl-1, downstream pro-apoptotic targets of the C. elegans p53 homolog Cep-1. Thus, we present evidence for a novel coactivator function of MAML1 for p53, independent of its function as a coactivator of Notch signaling pathway

Genomic Profiling of Two Histologically Distinct Rare Urothelial Cancers in a Clinical Setting to Identify Potential Therapeutic Options for Treatment and Management of Disease

Molecular profiling of urothelial cancers for therapeutic and prognostic potential has been very limited due to the absence of cancer-specific targeted therapies. We describe here 2 clinical cases with a histological diagnosis of an invasive sarcomatoid and a poorly differentiated carcinoma favoring urothelial with some neuroendocrine differentiation, two of the rarer types of urothelial cancers, which were evaluated for mutations in 212 genes for single-nucleotide variants and copy-number variants and 53 genes for fusions associated with solid tumors. In both cases, we identified variants in 2 genes, ARID1A and CDKN2A, indicative of the role of dysregulation of chromatin remodeling and cell cycle control as being common features of bladder cancer, consistent with the proposed model of tumorigenesis in these rare, highly aggressive pathological subtypes. The presence of a KRAS mutation in the poorly differentiated cancer and a TP53 mutation in the sarcomatoid tumor is indicative of a distinctive profile and adds a potential layer of molecular stratification to these rarer histological subtypes. We present a comparative analysis of the histological, clinical, and molecular profile of both cases and discuss the potential to delineate these tumors at the molecular level keeping in mind the possible therapeutic implications

Heparan Sulfate Mediates Infection of High-Neurovirulence Theiler's Viruses

The mechanisms by which Theiler's murine encephalomyelitis virus (TMEV) binds and enters host cells and the molecules involved are not completely understood. In this study, we demonstrate that the high-neurovirulence TMEV GDVII virus uses the glycosaminoglycan heparan sulfate (HS) as an attachment factor that is required for efficient infection. Studies based on soluble HS-mediated inhibition of attachment and infection, removal of HS with specific enzymes, and blocking with anti-HS antibodies establish that HS mediates GDVII virus entry into mammalian cells. Data from defined proteoglycan-deficient Chinese hamster ovary mutant cells further support the role of HS in GDVII infection and indicate that the extent of sulfation is critical for infection. Neuraminidase treatment of proteoglycan-deficient cells restores permissiveness to GDVII virus, indicating that sialic acid hinders direct access of virus to the protein entry receptor. A model of the potential steps in GDVII virus entry into mammalian cells involving HS is proposed

Evaluating gene fusions in solid tumors - clinical experience using an RNA based 53 gene next-generation sequencing panel.

Given the known association of gene fusions with solid tumor morbidity and the need to clarify the role of fusions in therapeutic, prognostic and diagnostic outcomes, we reviewed the positive yield rate for fusions in solid tumors using cases that were referred to our laboratory for clinical testing. We retrospectively evaluated results from 183 solid tumor samples that were received during a 24 month period for testing using the FusionSeq™ assay, an RNA-based Next Generation Sequencing (NGS) panel of 53 genes known to form fusions in solid tumors. Positive yield rate (actionable fusions) was evaluated for all samples tested, as a correlate for clinical utility. Twenty five fusions (actionable, variants of uncertain significance – VUS, and benign) were identified, of which 7 were classified as actionable gene fusions, resulting in an overall positive yield rate of ∼3.8% (7/183). Sixteen mostly novel fusions were classified and reported as VUSs. Five fusion events were classified as false positives, occurring due to mispriming or wild-type read through while 2 were classified as likely benign. Additionally 68% of fusions (17 of 25) detected in our study were present in prostate, colorectal, and gynecological cancers, suggesting that the frequency of fusions identified is dependent on specific tumor type. The high number of novel fusions identified highlights the potential for fusions in precision medicine

Implementation of a Customized Tertiary Analysis Platform for the Reporting of Somatic Variants

Precision medicine for oncology requires the evaluation of variants identified in molecular profiling of solid tumors and hematologic malignancies. This includes evaluation of pre-analytical and postanalytical quality metrics, variant interpretation, classification, and tiering as outlined in established guidelines, association with clinical significance such as FDA approved drugs and clinical trials, and finally comprehensive reporting. This study documents our experience with the customization and implementation of a software platform that facilitates these requirements for effective reporting of somatic variants

Chromosomal rearrangements and the pathogenesis of differentiated thyroid cancer

The majority of thyroid cancers arise from the follicular cells of the thyroid gland, which yield a wide variety of distinct morphotypes, ranging from relatively indolent lesions to the most malignant forms of cancer known. The remaining primary thyroid cancers arise from C cells within the gland and result primarily from mutations of the RET protooncogene, germ line mutations of which give rise to the various forms of multiple endocrine neoplasia. The most common of the follicular cell-derived cancers are papillary carcinomas, (PTC), followed by follicular carcinomas (FTC) and its Hurthle cell variant (HCC) and finally anaplastic carcinomas (ATC). The pathogenesis of many thyroid cancers, of both PTC and FTC morphotype, involves chromosomal translocations. Rearrangements of the RET protoconcogene are known to be involved in the pathogenesis of ca. 50% of PTC. A similar proportion of FTC have been associated with a t(2;3)(q13;p25) translocation, fusing the thyroid-specific transcription factor PAX8 with the peroxisome proliferator-activated receptor gamma (PPARγ) nuclear receptor, a ubiquitously expressed transcription factor. These rearrangements have analogy with translocations in erythropoetic cells, which form the only other known group of human malignancies that are largely the result of chromosomal translocation events. In this review we compare and contrast the oncogenic properties of thyroid and erythroid chromosomal transformations and speculate on mechanisms leading to their formation