Efficient 1-Hour Technetium-99 m Pyrophosphate Imaging Protocol for the Diagnosis of Transthyretin Cardiac Amyloidosis.

BACKGROUND: Technetium-99 m pyrophosphate protocols for transthyretin cardiac amyloidosis diagnosis have variably used 1- and 3-hour imaging time points. We investigated whether imaging at 1 hour with superior efficiency had comparable diagnostic accuracy as 3-hour imaging. METHODS: This is a registry analysis of patients with suspected transthyretin cardiac amyloidosis referred for technetium-99 m pyrophosphate at a single tertiary center from June 2015 through January 2019. Patients underwent planar and single-photon emission computed tomography (SPECT) imaging at 1 and 3 hours. A positive Tc-99m pyrophosphate study was defined by the presence of diffuse myocardial tracer uptake on SPECT. For planar imaging, visual semiquantitative (grades 0-3, ≥2 considered positive) and quantitative heart to contralateral ratios (≥1.5 considered positive) were used. RESULTS: Two hundred thirty-three patients (69% men; median age, 77 [69-83] years) underwent the study protocol. There were 60 (25.8%) patients with diffuse myocardial uptake, 1 (0.4%) with regional uptake, and 172 (73.8%) with no myocardial uptake. Results of SPECT were identical at 1 and 3 hours. Planar imaging at 1 hour had 98% sensitivity and 96% specificity. Planar grade 0 uptake or heart to contralateral ratio ≤1.2 and planar grade 3 uptake or heart to contralateral ratio ≥2.0 were always associated with negative and positive SPECT, respectively. For planar grades 1 and 2 uptake and heart to contralateral ratio 1.3 to 1.9, SPECT was needed to make a diagnosis. No patient with light-chain cardiac amyloidosis had positive SPECT. CONCLUSIONS: An efficient 1-hour technetium-99 m pyrophosphate protocol had comparable diagnostic performance to a 3-hour protocol.

Disulfiram (Antabuse) Activates ROS-Dependent ER Stress and Apoptosis in Oral Cavity Squamous Cell Carcinoma.

A paucity of advances in the development of novel therapeutic agents for squamous cell carcinomas of the head and neck, oral cavity (OSCC) and oropharynx, has stagnated disease free survival rates over the past two decades. Although immunotherapies targeted against checkpoint inhibitors such as PD-1 or CTLA-4 are just now entering the clinic for late stage disease with regularity the median improvement in overall survival is only about three months. There is an urgent unmet clinical need to identify new therapies that can be used alone or in combination with current approaches to increase survival by more than a few months. Activation of the apoptotic arm of the unfolded response (UPR) with small molecules and natural products has recently been demonstrated to be a productive approach in pre-clinical models of OSCC and several other cancers. The aim of current study was to perform a high throughput screen (HTS) with a diverse chemical library to identify compounds that could induce CHOP, a component of the apoptotic arm of the UPR. Disulfiram (DSF, also known as Antabuse) the well-known aversion therapy used to treat chronic alcoholism emerged as a hit that could generate reactive oxygen species, activate the UPR and apoptosis and reduce proliferation in OSCC cell cultures and xenografts. A panel of murine embryonic fibroblasts null for key UPR intermediates (e.g., Chop and Atf4) was resistant to DSF suggesting that an intact UPR is a key element of the mechanism regulating the antiproliferative effects of DSF.

Borrelidin Induces the Unfolded Protein Response in Oral Cancer Cells and Chop-Dependent Apoptosis.

Oral squamous cell carcinoma (OSCC) is the most common cancer affecting the oral cavity, and US clinics will register about 30,000 new patients in 2015. Current treatment modalities include chemotherapy, surgery, and radiotherapy, which often result in astonishing disfigurement. Cancers of the head and neck display enhanced levels of glucose-regulated proteins and translation initiation factors associated with endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). Previous work demonstrated that chemically enforced UPR could overwhelm these adaptive features and selectively kill malignant cells. The threonyl-tRNA synthetase (ThRS) inhibitor borrelidin and two congeners were discovered in a cell-based chemical genomic screen. Borrelidin increased XBP1 splicing and led to accumulation of phosphorylated eIF2α and UPR-associated genes, prior to death in panel of OSCC cells. Murine embryonic fibroblasts (MEFs) null for GCN2 and PERK were less able to accumulate UPR markers and were resistant to borrelidin. This study demonstrates that UPR induction is a feature of ThRS inhibition and adds to a growing body of literature suggesting ThRS inhibitors might selectively target cancer cells.

Celastrol induces unfolded protein response-dependent cell death in head and neck cancer.

The survival rate for patients with oral squamous cell carcinoma (OSCC) has not seen marked improvement in recent decades despite enhanced efforts in prevention and the introduction of novel therapies. We have reported that pharmacological exacerbation of the unfolded protein response (UPR) is an effective approach to killing OSCC cells. The UPR is executed via distinct signaling cascades whereby an initial attempt to restore folding homeostasis in the endoplasmic reticulum during stress is complemented by an apoptotic response if the defect cannot be resolved. To identify novel small molecules able to overwhelm the adaptive capacity of the UPR in OSCC cells, we engineered a complementary cell-based assay to screen a broad spectrum of chemical matter. Stably transfected CHO-K1 cells that individually report (luciferase) on the PERK/eIF2α/ATF4/CHOP (apoptotic) or the IRE1/XBP1 (adaptive) UPR pathways, were engineered [1]. The triterpenoids dihydrocelastrol and celastrol were identified as potent inducers of UPR signaling and cell death in a primary screen and confirmed in a panel of OSCC cells and other cancer cell lines. Biochemical and genetic assays using OSCC cells and modified murine embryonic fibroblasts demonstrated that intact PERK-eIF2-ATF4-CHOP signaling is required for pro-apoptotic UPR and OSCC death following celastrol treatment.