A Subset of Latency-Reversing Agents Expose HIV-Infected Resting CD4+ T-Cells to Recognition by Cytotoxic T-Lymphocytes.

Resting CD4+ T-cells harboring inducible HIV proviruses are a critical reservoir in antiretroviral therapy (ART)-treated subjects. These cells express little to no viral protein, and thus neither die by viral cytopathic effects, nor are efficiently cleared by immune effectors. Elimination of this reservoir is theoretically possible by combining latency-reversing agents (LRAs) with immune effectors, such as CD8+ T-cells. However, the relative efficacy of different LRAs in sensitizing latently-infected cells for recognition by HIV-specific CD8+ T-cells has not been determined. To address this, we developed an assay that utilizes HIV-specific CD8+ T-cell clones as biosensors for HIV antigen expression. By testing multiple CD8+ T-cell clones against a primary cell model of HIV latency, we identified several single agents that primed latently-infected cells for CD8+ T-cell recognition, including IL-2, IL-15, two IL-15 superagonists (IL-15SA and ALT-803), prostratin, and the TLR-2 ligand Pam3CSK4. In contrast, we did not observe CD8+ T-cell recognition of target cells following treatment with histone deacetylase inhibitors or with hexamethylene bisacetamide (HMBA). In further experiments we demonstrate that a clinically achievable concentration of the IL-15 superagonist ‘ALT-803’, an agent presently in clinical trials for solid and hematological tumors, primes the natural ex vivo reservoir for CD8+ T-cell recognition. Thus, our results establish a novel experimental approach for comparative evaluation of LRAs, and highlight ALT-803 as an LRA with the potential to synergize with CD8+ T-cells in HIV eradication strategies.

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Characterization of antibody-drug conjugates by mass spectrometry: advances and future trends.

Antibody-drug conjugates (ADCs) are emerging modalities in the pharmaceutical industry. The unique target-specific binding of antibody allows targeted delivery of cytotoxic small molecules to cancer cells, and thus expands the therapeutic window. However, in-depth characterization of ADCs is complex because it involves the characterization of antibody, conjugated molecules and antibody conjugates as a whole. In this review, we describe the practical use of mass spectrometry for ADC characterization including qualitative and quantitative analysis. Technical advances, limitations and future trends will also be discussed.
Copyright © 2016. Published by Elsevier Ltd.

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Base pairing and structural insights into the 5-formylcytosine in RNA duplex.

5-Formylcytidine (f(5)C), a previously discovered natural nucleotide in the mitochondrial tRNA of many species including human, has been recently detected as the oxidative product of 5-methylcytidine (m(5)C) through 5-hydroxymethylcytidine (hm(5)C) in total RNA of mammalian cells. The discovery indicated that these cytosine derivatives in RNA might also play important epigenetic roles similar as in DNA, which has been intensively investigated in the past few years. In this paper, we studied the base pairing specificity of f(5)C in different RNA duplex contexts. We found that the 5-formyl group could increase duplex thermal stability and enhance base pairing specificity. We present three high-resolution crystal structures of an octamer RNA duplex [5′-GUA(f(5)C)GUAC-3′]2that have been solved under three crystallization conditions with different buffers and pH values. Our results showed that the 5-formyl group is located in the same plane as the cytosine base and forms an intra-residue hydrogen bond with the amino group in the N4 position. In addition, this modification increases the base stacking between the f(5)C and the neighboring bases while not causing significant global and local structure perturbations. This work provides insights into the effects of 5-formylcytosine on RNA duplex.
© The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

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Cancer and bone fractures in observational follow-up of the RECORD study.

The RECORD study evaluated the effects of rosiglitazone on cardiovascular outcomes. A 4-year observational follow-up was added to the study to monitor the occurrence of cancer and bone fractures. We present the cancer and bone fracture data aggregated across the main study and its observational follow-up.
RECORD was a multicentre, open-label trial in people with type 2 diabetes on metformin or sulfonylurea monotherapy randomly assigned to addition of rosiglitazone (n = 2,220) or to a combination of metformin and sulfonylurea (n = 2,227). At the end of the main study, patients stopped study drug and were invited to enter the observational follow-up during which glucose-lowering treatment was selected by the patient’s physician. Serious adverse events of cancer and serious and non-serious events of bone fracture were recorded. The study is registered with ClinicalTrials.gov, number NCT00379769.
Of the 4,447 patients comprising the intent-to-treat population, 2,546 entered the observational follow-up (1,288 rosiglitazone, 1,258 metformin/sulfonylurea) and added 9,336 patient-years experience to the main RECORD study, making an aggregate of 33,744 patient-years. Based on the totality of follow-up, malignancies were reported in 179 of 2,220 patients (8.1 %) in the group originally randomised to rosiglitazone and in 195 of 2,227 patients (8.8 %) in the group allocated metformin/sulfonylurea [relative risk, RR, 0.92 (95 % CI 0.76-1.12)]. More patients reported bone fractures in the rosiglitazone group (238, 10.7 %) than in the metformin/sulfonylurea control [151, 6.8 %; RR 1.58 (1.30-1.92)]. For women, the corresponding figures were rosiglitazone 156 (14.5 %), metformin/sulfonylurea 91 (8.5 %), RR 1.71 (1.34-2.18), and for men, the corresponding figures were rosiglitazone 82 (7.2 %), metformin/sulfonylurea 60 (5.2 %), RR 1.37 (0.99-1.90). Potentially high-morbidity fractures (hip, pelvis, femur, and spine) occurred in the same number of patients (31, 1.4 %) in the two treatment groups.
We conclude that data from a 4-year observational follow-up, combined with the main RECORD study data, do not suggest an increased risk of cancer in patients randomised to rosiglitazone combination use compared with those randomised to metformin/sulfonylurea. Consistent with the main study, rosiglitazone is associated with an increased risk of peripheral bone fracture in women, and probably in men, but the combined data do not suggest an increase in potentially high-morbidity (hip, pelvis, femur, and spine) fractures.

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The hepatocyte growth factor antagonist NK4 inhibits indoleamine-2,3-dioxygenase expression via the c-Met-phosphatidylinositol 3-kinase-AKT signaling pathway.

Indoleamine-2,3-dioxygenase (IDO) is an immunosuppressive enzyme involved in tumor malignancy. However, the regulatory mechanism underlying its involvement remains largely uncharacterized. The present study aimed to investigate the hypothesis that NK4, an antagonist of hepatocyte growth factor (HGF), can regulate IDO and to characterize the signaling mechanism involved. Following successful transfection of the human ovarian cancer cell line SKOV-3 (which constitutively expresses IDO) with an NK4 expression vector, we observed that NK4 expression suppressed IDO expression; furthermore, NK4 expression did not suppress cancer cell growth in vitro [in the absence of natural killer (NK) cells], but did influence tumor growth in vivo. In addition, NK4 enhanced the sensitivity of cancer cells to NK cells in vitro and promoted NK cell accumulation in the tumor stroma in vivo. In an effort to clarify the mechanisms by which NK4 interacts with IDO, we performed investigations utilizing various biochemical inhibitors. The results of these investigations were as follows. First, c-Met (a receptor of HGF) tyrosine kinase inhibitor PHA-665752, and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 both suppress IDO expression. Second, enhanced expression of PTEN (a known tumor suppressor) via negative regulation within a PI3K-AKT pathway, inhibits IDO expression. Conversely, neither the MEK1/2 inhibitor U0126 nor the STAT3 inhibitor WP1066 affects IDO expression. These results suggest that NK4 inhibits IDO expression via a c-Met-PI3K-AKT signaling pathway.

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