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T cells engineered to express chimeric antigen receptors (CARs) targeting CD19 have demonstrated impressive activity against relapsed or refractory B cell cancers yet fail to induce durable remissions for nearly half of patients treated. Enhancing the efficacy of this therapy requires detailed understanding of the molecular circuitry that restrains CAR-driven anti-tumor T cell function. We developed and validated an in vitro model that drives T cell dysfunction through chronic CAR activation and interrogated how CAR costimulatory domains, central components of CAR structure and function, contribute to T cell failure. We found that chronic activation of CD28-based CARs results in activation of classical T cell exhaustion programs and development of dysfunctional cells that bear the hallmarks of exhaustion. In contrast, 41BB-based CARs activate a divergent molecular program and direct differentiation of T cells into a novel cell state. Interrogation of CAR T cells from a patient with progressive lymphoma confirmed activation of this novel program in a failing clinical product. Further, we demonstrate that 41BB-dependent activation of the transcription factor FOXO3 is directly responsible for impairing CAR T cell function. These findings identify that costimulatory domains are critical regulators of CAR-driven T cell failure and that targeted interventions are required to overcome costimulation-dependent dysfunctional programs.

Background/purpose Positional obstructive sleep apnea (OSA) is defined as an apnea hypopnea index at least twice as high in the supine position as in the lateral position. Whether a positional OSA patient persistently has positional OSA in the follow-up period is unknown. This study was conducted to investigate the maintenance of the positional effect on OSA patients and the predictors of changing from positional OSA to nonpositional OSA. Methods Patients who were diagnosed to have positional OSA were screened for a follow-up polysomnography (PSG), which evaluated the effect of the same lateral position as baseline PSG on the severity of OSA. Those who met the criteria of positional OSA in both PSGs were classified as the unchanged group, the others were classified as the changed group. Results Seventy-eight positional OSA patients were enrolled in the final analyses. Twenty-seven of the enrolled patients (35%) were changed to nonpositional OSA patients in the second PSG. A higher apnea index in the lateral position was found in the changed group compared with that in the unchanged group ( p = 0.02). Logistic regression also showed that the apnea index in the lateral position was the only independent predictor of changing from positional OSA to nonpositional OSA in the follow-up PSG (odds ratio = 1.13, p = 0.004). Conclusion One-third of positional OSA patients who had a high apnea index in the lateral position tends to become nonpositional OSA patients in the follow-up PSG and must be closely monitored if receiving positional therapy only.

Primary and metastatic neoplasms of the liver account for more than a million deaths per year worldwide. Despite decades of research, effective novel therapies for these cancers are urgently needed. Oncolytic virotherapeutics represent a novel class of pharmacophore that holds promise for the treatment of hepatic neoplasms. Cancer-specific replication is followed by oncolysis, virus spreading and infection of adjacent cancer cells. This process is then repeated. Virotherapeutics target multiple genetic pathways involved in carcino-genesis, and demonstrate activity against apoptosis-resistant tumour cells. This platform can also exploit the advantage of multiple intrinsic anti-cancer therapeutic mechanisms, combining direct viral oncolysis with therapeutic transgene expression. Recent advances in pre-clinical and clinical studies are revealing the potential of this unique therapeutic class, in particular for liver cancers. This review summarizes the available data on applying oncolytic virotherapeutics to hepatic neoplasms to date, and discusses the challenges and future directions for virotherapy.

Transcriptional silencing in yeast is mediated by the interactions of silent information regulator (Sir) proteins with chromatin and with one another. The stable association of Sir3 with Sir4 is mediated by a C-terminal region of Sir3 that has additional functions including the dimerization of Sir3. We have developed a simple, robust expression screening methodology that allows for the unbiased identification of functional protein domains expressed from nested-deletion libraries of full-length genes. Using these methodologies, Sir3 dimerization was shown to be mediated by two separate domains. One of these domains also binds cooperatively to the C-terminal coiled-coil motif of Sir4 and dimerization further increases the affinity of Sir3 for Sir4. The resulting Sir3-Sir4 complexes form progressively higher order assemblies with increasing protein concentration, with implications for the mechanism of gene silencing.

Head and neck cancers usually present with advanced disease and novel therapies are urgently needed. Genetic therapy aims at restoring malfunctioned tumor suppressor gene(s) or introducing proapoptotic genes. Oncolytic virotherapeutics induce multiple cycles of cancer-specific virus replication, followed by oncolysis, virus spreading and infection of adjacent cancer cells. Oncolytic viruses can also be armed to express therapeutic transgene(s). Recent advances in preclinical and clinical studies are revealing the potential of both therapeutic classes for advanced head and neck cancers, including the approval of two products (Gendicine and H101) by a governmental agency. This review summarizes the available clinical data to date and discusses the challenges and future directions.

The yeast silent information regulators Sir2, Sir3, and Sir4 physically interact with one another to establish a transcriptionally silent state by forming repressive chromatin structures. The Sir4 protein contains binding sites for both Sir2 and Sir3, and these protein-protein interactions are required for gene silencing. Here, we report the X-ray structure of the coiled-coil dimerization motif within the C-terminus of Sir4 and show that it forms a stable 1:1 complex with a dimeric fragment of Sir3 (residues 464–978). We have identified a cluster of residues on the surface of the Sir4 coiled coil required for specific interactions with Sir3. The histone deacetylase Sir2 can also bind to this complex, forming a ternary complex with the truncated Sir3 and Sir4 proteins. The dual interactions of Sir4 with Sir3 and Sir2 suggest a physical basis for recruiting Sir3 to chromatin by virtue of its interactions with Sir4 and with deacetylated histones in chromatin.

The DNA-binding domain of the Oct-1 transcription factor, POU, recognizes a defined DNA sequence known as the octamer element to regulate the expression of both general and cell-type-specific genes. The two-part DNA-binding domain partially encircles the DNA to recognize the eight base pairs of the octamer element. We have characterized the binding of Oct-1/POU to an octamer element using isothermal titration calorimetry. As found for other cognate protein/DNA complexes, the formation of the Oct-1 POU/DNA complex is associated with a large negative heat capacity change, DeltaC(p)()(, obs). However, the observed change is much greater than expected by empirical relationships with buried surface area. Supported by data from proteolysis studies on the free and DNA-bound protein, we propose that the discrepancy in heat capacity arises principally from the partial folding of the Oct-1 POU protein upon complex formation. Formation of the Oct-1 POU/DNA complex is strongly dependent on ionic strength, and the detailed quantification of this relationship suggests that six charged contacts are made between the protein and the phosphate groups of the DNA. This agrees with observations from the crystal structure of an Oct-1 POU/DNA complex.

The expression of immunoglobulin genes is controlled in part by the DNA-binding protein Oct-1 and the B cell-specific transcription co-activator, Bob1 (also known as OCA-B or OBF-1) that together form a complex on the Igκ promoter. We have characterised the assembly of the ternary complex using biophysical methods. Bob1 binds specifically as a monomer to the complex of the Oct-1 DNA-binding domain (Oct-1 POU) and the Igκ promoter, but binds weakly to either Oct-1 POU or the Igκ promoter alone, indicating that both are required to make an avid complex. Ternary complex formation requires a defined DNA sequence, as the stability of the complex can be strongly affected by a single base-pair change or by removing 5-methyl groups from selected thymine bases. In isolation, Bob1 appears to have little secondary structure, but may become partially structured upon recruitment into the ternary complex as demonstrated by circular dichroism spectra and calorimetry. These and other findings suggest that ternary complex formation requires a defined geometry of the POU/DNA complex, and that the co-activator makes stereo-specific contacts to both the POU protein and the major groove of the DNA that induces its fold.