Alteration of gammaretroviral vector integration patterns by insertion of histone and leucine zipper into integrase.

Retroviral vectors show long-term gene expression in gene therapy through the integration of transgenes into the human cell genome. Murine leukemia virus (MLV), a well-studied gammaretrovirus, has been often used as a representative retroviral vector. However, frequent integrations of MLV-based vectors into transcriptional start sites (TSSs) could lead to the activation of oncogenes by enhancer effects of the genetic components within the vectors. Therefore, the MLV integration preference for TSSs limits its wider use in clinical applications. To reduce the integration preference of MLV-based vectors, we attempted to perturb the structure of the viral integrase that plays a key role in determining integration sites. For this goal, we inserted histones and leucine zippers, having DNA-binding property, into internal sites of MLV integrase. This integrase engineering yielded multiple mutant vectors that showed significantly different integration patterns compared with that of wild-type vector. Some mutant vectors did not prefer the key regulatory genomic domains of human cells, TSSs. Moreover, a couple of engineered vectors did not integrate into the genomic sites near the TSSs of oncogenes. Overall, this study suggests that structural perturbation of integrase is a simple way to develop safer MLV-based retroviral vectors for use in clinical applications.

Curcumin inhibits the cancer­associated fibroblast­derived chemoresistance of gastric cancer through the suppression of the JAK/STAT3 signaling pathway.

The present study aimed to investigate whether the Janus­activated kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is a critical mechanism underlying the cancer­associated fibroblast (CAF)­induced chemoresistance of gastric cancer (GC). In addition, the present study tried to suggest a natural product to compromise the effects of CAF on the chemoresistance of GC. The results of cell proliferation assay revealed that the conditioned medium (CM) collected from CAFs further increased resistance to 5­fluorouracil (5­FU) in GC cell lines. Secretome analysis revealed that the levels of several secreted proteins, including C­C motif chemokine ligand 2, C­X­C motif chemokine ligand 1, interleukin (IL)­6 and IL­8, were increased in the CM from CAFs co­cultured with cancer cells compared to CM from cancer cells. Western blot analysis revealed that CAFs activated the JAK/STAT3 signaling pathway in cancer cells. The experimental models revealed that curcumin abrogated the CAF­mediated activation of the JAK/STAT3 signaling pathway in GC cells. In vivo data revealed the synergistic effects of curcumin with 5­FU treatment in xenograft GC tumors. These data strongly suggest that the suppression of the JAK/STAT3 signaling pathway counteracts the CAF­induced chemoresistance of GC cells. It is suggested that curcumin may be a suitable natural product which may be used to overcome chemoresistance by inhibiting the CAF­induced activation of the JAK/STAT3 signaling pathway in GC.

Correlation-based and feature-driven mutation signature analyses to identify genetic features associated with DNA mutagenic processes in cancer genomes.

Mutation signatures represent unique sequence footprints of somatic mutations resulting from specific DNA mutagenic and repair processes. However, their causal associations and the potential utility for genome research remain largely unknown. In this study, we performed PanCancer-scale correlative analyses to identify the genomic features associated with tumor mutation burdens (TMB) and individual mutation signatures. We observed that TMB was correlated with tumor purity, ploidy, and the level of aneuploidy, as well as with the expression of cell proliferation-related genes representing genomic covariates in evaluating TMB. Correlative analyses of mutation signature levels with genes belonging to specific DNA damage-repair processes revealed that deficiencies of NHEJ1 and ALKBH3 may contribute to mutations in the settings of APOBEC cytidine deaminase activation and DNA mismatch repair deficiency, respectively. We further employed a strategy to identify feature-driven, de novo mutation signatures and demonstrated that mutation signatures can be reconstructed using known causal features. Using the strategy, we further identified tumor hypoxia-related mutation signatures similar to the APOBEC-related mutation signatures, suggesting that APOBEC activity mediates hypoxia-related mutational consequences in cancer genomes. Our study advances the mechanistic insights into the TMB and signature-based DNA mutagenic and repair processes in cancer genomes. We also propose that feature-driven mutation signature analysis can further extend the categories of cancer-relevant mutation signatures and their causal relationships.

Spatially Distinct Reprogramming of the Tumor Microenvironment Based On Tumor Invasion in Diffuse-Type Gastric Cancers.

PURPOSE: Histologic features of diffuse-type gastric cancer indicate that the tumor microenvironment (TME) may substantially impact tumor invasiveness. However, cellular components and molecular features associated with cancer invasiveness in the TME of diffuse-type gastric cancers are poorly understood. EXPERIMENTAL DESIGN: We performed single-cell RNA-sequencing (scRNA-seq) using tissue samples from superficial and deep invasive layers of cancerous and paired normal tissues freshly harvested from five patients with diffuse-type gastric cancer. The scRNA-seq results were validated by immunohistochemistry (IHC) and duplex in situ hybridization (ISH) in formalin-fixed paraffin-embedded tissues. RESULTS: Seven major cell types were identified. Fibroblasts, endothelial cells, and myeloid cells were categorized as being enriched in the deep layers. Cell type-specific clustering further revealed that the superficial-to-deep layer transition is associated with enrichment in inflammatory endothelial cells and fibroblasts with upregulated CCL2 transcripts. IHC and duplex ISH revealed the distribution of the major cell types and CCL2-expressing endothelial cells and fibroblasts, indicating tumor invasion. Elevation of CCL2 levels along the superficial-to-deep layer axis revealed the immunosuppressive immune cell subtypes that may contribute to tumor cell aggressiveness in the deep invasive layers of diffuse-type gastric cancer. The analyses of public datasets revealed the high-level coexpression of stromal cell-specific genes and that CCL2 correlated with poor survival outcomes in patients with gastric cancer. CONCLUSIONS: This study reveals the spatial reprogramming of the TME that may underlie invasive tumor potential in diffuse-type gastric cancer. This TME profiling across tumor layers suggests new targets, such as CCL2, that can modify the TME to inhibit tumor progression in diffuse-type gastric cancer.See related commentary by Huang and Brekken, p. 6284.

Blocking of monocyte-associated B7-H1 (CD274) enhances HCV-specific T cell immunity in chronic hepatitis C infection.

The establishment of a chronic hepatitis C (CHC) infection is associated with defective HCV-specific T cell responses. Recent studies suggest that negative T cell regulators such as programmed death 1 (PD-1) contribute to the impairment of virus-specific T cell functions in chronic viral infections. However, the implication of peripheral monocytes from CHC patients in the inhibition of HCV-specific T cell responses is only partially defined. In this study, we found that B7-H1, a ligand of PD-1, was significantly up-regulated on monocytes of CHC patients. Proliferation of T cells in response to anti-CD3 antibody was directly suppressed by B7-H1+CD14+ monocytes, and this suppression was reversed by addition of antagonistic B7-H1 mAb. Furthermore, blocking of monocyte-associated B7-H1 (moB7-H1) significantly enhanced the frequency of IFN-gamma-producing, HCV-specific CD4+ and CD8+ effector T cells and the production of Th1 cytokines, such as IL-2 but not Th2 cytokines, including IL-4 and IL-10. Upon B7-H1 blockade, production of perforin was also increased in CD8+ T cells stimulated with HCV peptides. Our findings suggest that moB7-H1 inhibits HCV-specific CD4+ and CD8+ T lymphocyte proliferation and suppresses Th1 cytokine production and perforin secretion. Blockade of the B7-H1 pathway thus represents an attractive approach in the treatment of chronic HCV infection.

Blockade of endogenous B7-H1 suppresses antibacterial protection after primary Listeria monocytogenes infection.

B7-H1 (also known as CD274 and PD-L1) is a cosignalling molecule regulating T-cell immunity positively or negatively in vivo. However, little is known about the role of endogenous B7-H1 in bacterial infection. We found that B7-H1 expression was up-regulated in various cell populations including CD4+ and CD8+ T cells, natural killer (NK) cells and macrophages following Listeria monocytogenes infection. Administration of the antagonistic B7-H1 monoclonal antibody resulted in a significant increase in mortality in mice infected with a lethal dose of L. monocytogenes compared with mice given the control immunoglobulin. In vivo blockade of B7-H1 greatly inhibited the production of tumour necrosis factor (TNF)-alpha and nitric oxide, key effector molecules responsible for intracellular killing by macrophages. B7-H1 blockade also suppressed the expression of granzyme B and interferon (IFN)-gamma by NK cells. Interestingly, blocking of endogenous B7-H1 selectively inhibited CD8+ T cells rather than CD4+ T cells in response to L. monocytogenes infection, as evidenced by the reduction of IFN-gamma production and the expression of effector surface markers including CD62L(int/low) and CD44(high) in CD8+ T cells from mice given anti-B7-H1 monoclonal antibody. In addition, we found that the proliferation of listeriolysin-O (LLO)-specific and IFN-gamma-producing L. monocytogenes-reactive CD8+ T cells was significantly decreased not only in the effector phase but also in the memory phase in the presence of anti-B7-H1 antibody. Our findings thus suggest that endogenous B7-H1 can provide positive costimulatory signals for innate and adaptive immunity leading to protection against intracellular bacterial infection.

Co-inhibitory role of T-cell-associated B7-H1 and B7-DC in the T-cell immune response.

B7-H1 and B7-DC expressed on antigen-presenting cells inhibit the T-cell response via the PD-1 counter-receptor on T cells, and co-stimulate T-cell immunity under certain conditions via an unidentified co-stimulatory receptor. However, little is known about the functional consequence of T-cell-associated B7-H1 or B7-DC in the T-cell immune response. Therefore, we evaluated the physiological role of B7-H1 and B7-DC expressed on T cells in terms of cell proliferation and cytokine production by alloreactive T cells. We found that PD-1, B7-H1, and B7-DC were up-regulated in alloreactive CD4(+) and CD8(+) T cells in vitro and in vivo. In the alloreactive T-T model, blockade of the B7-H1:PD-1 or B7-DC:PD-1 pathways significantly increased the proliferation, and IFN-gamma and IL-2 production of alloreactive T cells, although it did not affect the production of other cytokines, including IL-4, IL-10, and IL-12. The data indicate that T-cell-associated B7-H1 and B7-DC negatively regulate the T-cell response via the T-T interaction.

B7-H1 (CD274) inhibits the development of herpetic stromal keratitis (HSK).

The co-signaling molecule B7-H1 (CD274) functions as both a co-inhibitor through programmed death-1 (PD-1) receptor and a co-stimulator via an as-yet-unidentified receptor on T cells. We investigated the physiological role of endogenous B7-H1 in the pathogenesis of herpetic stromal keratitis (HSK) caused by herpes simplex virus type 1 (HSV-1). Following HSV-1 infection of the cornea of mice, B7-H1 expression was up-regulated in the CD11b+ macrophage population in the draining lymph nodes (dLN) and in the inflamed cornea. In addition, HSV-1 infection significantly increased PD-1 expression on CD4+ T cells in the dLN and inflamed cornea. The administration of antagonistic B7-H1 monoclonal antibody resulted in the proliferation of HSV-specific CD4+ T cells that secreted interferon (INF)-gamma, and inhibited the apoptosis of HSV-specific CD4+ T cells, which exaggerated HSK. These results strongly suggest that the B7-H1 may be involved in suppression of the development of HSK.

Tyrosine kinase-mediated activation of NADPH oxidase enhances proliferative capacity of diabetic vascular smooth muscle cells.

To investigate a potential molecular basis for a link between diabetes and atherosclerosis, experiments were performed to determine the role of NADPH oxidase in the enhanced proliferative capacity of vascular smooth muscle cells (VSMC) from OLETF rat, an animal model of type 2 diabetes. An enhanced proliferative response to 10% fetal bovine serum with an increased cell cycle progression from G1 to S phase as well as an augmented superoxide generation with an increased NADPH oxidase activity were observed in diabetic versus control VSMC. Both the enhanced proliferation and superoxide generation in diabetic VSMC were significantly attenuated not only by diphenyleneiodonium (10 microM) and apocynin (100 microM), NADPH oxidase inhibitors but also by protein tyrosine kinase inhibitors such as genistein (100 microM) and AG 112 (100 microM). Furthermore, the enhanced NADPH oxidase activity in diabetic VSMC was significantly attenuated by genistein and AG112, but not by daidzein (100 microM), a genistein analogue devoid of protein tyrosine kinase inhibitory properties. Based on these results, it is suggested that the enhanced proliferative capacity of diabetic VSMC is closely related to the activation of NADPH oxidase that is induced through activation of protein tyrosine kinase.

Effect of Di-(2-ethylhexyl)-phthalate on Sphingolipid Metabolic Enzymes in Rat Liver.

Di-(2-ethylhexyl)-phthalate (DEHP), the most widely utilized industrial plastizer and a ubiquitous environmental contaminant, can act on peroxisome proliferators-activated nuclear hormone receptor family (PPAR) isoforms. To understand the contribution of sphingolipid metabolism to DEHP-induced hepatotoxicity, effect of DEHP exposure on activities of sphingolipid metabolic enzymes in rat liver was investigated. DEHP (250, 500 or 750 mg/kg) was administered to the rats through oral gavage daily for 28 days. The activities of acidic and alkaline ceramidases were slightly increased in 250 mg/kg DEHP-administered rat livers and significantly elevated in 500 mg/kg DEHP-administered ones, although the level of 750 mg/kg DEHP-administered ones was not increased. Neutral ceramidase, acidic and neutral sphingomyelinases, sphingomyeline synthase and ceramide syhthase were not changed at all by DEHP exposure. Therefore, acidic and alkaline ceramidases might play important roles in DEHP-induced hepatotoxicity.

Effects of chronic alcohol consumption on expression levels of APP and Aß-producing enzymes.

Chronic alcohol consumption contributes to numerous diseases, including cancers, cardiovascular diseases, and liver cirrhosis. Epidemiological studies have shown that excessive alcohol consumption is a risk factor for dementia. Along this line, Alzheimer's disease (AD) is the most common form of dementia and is caused by the accumulation of amyloid-ß (Aß plaques in neurons. In this study, we hypothesized that chronic ethanol consumption is associated with pathological processing of APP in AD. To investigate the relationship between chronic alcohol consumption and Aß production, brain samples from rats fed an alcohol liquid diet for 5 weeks were analyzed. We show that the expression levels of APP, BACE1, and immature nicastrin were increased in the cerebellum, hippocampus, and striatum of the alcohol-fed group compared to the control group. Total nicastrin and PS1 levels were induced in the hippocampus of alcohol-fed rats. These data suggest that the altered expression of APP and Aß-producing enzymes possibly contributes to the chronic alcohol consumption-mediated pathogenesis of AD.

Selenium attenuates A beta production and A beta-induced neuronal death.

The objective of the present study was to examine the role of selenium in the metabolism of A beta and in A beta-induced neuronal death. Selenium treatment significantly reduced A beta 40, A beta 42, and sAPP beta production by reducing A beta producing beta-secretase and gamma-secretase activities. The lipid peroxidation product 4-Hydroxynonenal (HNE)-induced transcription of beta-secretase (BACE1) was blocked by selenium. Finally, our data show that selenium protects against HNE and A beta-mediated toxicity in primary cultured neurons. The present study suggests that selenium may be able to salvage the neuronal degeneration of Alzheimer's disease, thereby limiting beta-amyloid production and neuronal death.

Contribution of gamma-secretase to calcium-mediated cell death.

Presenilins are the catalytic subunit of the large gamma-secretase complex, that promotes intramembranous proteolysis of the beta-amyloid precursor protein (APP), resulting in the production of beta-amyloid (A beta). Mutant presenilin causes early-onset familial Alzheimer's disease (FAD), is related to abnormal Ca(2+) signaling, and render cells vulnerable to cell death. In the present study, we demonstrated that Ca(2+)-mediated cell death is functionally associated with gamma-secretase activity. We found that gamma-secretase activity was elevated during Ca(2+)-mediated cell death. Using selective gamma-secretase inhibitors, we examined the role of gamma-secretase in cell death triggered by increased intracellular Ca(2+). Indeed, treatment with the selective gamma-secretase inhibitors, compound E, DAPT, or L-685.458 significantly decreased Ca(2+)-triggered cell death with that of the controls, but did not affect staurosporin or tunicamycin-mediated cell death. These results implicate the role of gamma-secretase activity in Ca(2+)-mediated cell death.

Interpretation of interleukin-2 receptor alpha positive cells during induction chemotherapy for adult acute myelogenous leukaemia patients.

To correlate clinical outcomes with the expression of interleukin-2 receptor alpha (CD25) positive cells during induction chemotherapy (IC) in adult patients with acute myeloid leukaemia (AML), we investigated the prognostic importance of subsets of peripheral blood (PB) CD45+CD25+ cells. Seventy-five patients with newly diagnosed AML received the same initial IC; and serial PB samples were taken. The gated CD45/CD25 cell populations were used to compare the intensity of immunophenotypic signals based on the treatment timeline. Patients who responded poorly to IC demonstrated exceptionally higher levels of PB CD45+CD25+ cells by percentage (p = 0.003) or by absolute count (p = 0.046) on the seventh day (D + 7) of initial IC. In addition, patients in complete remission (CR) (n = 61) demonstrated relatively lower levels of steady PB CD45+CD25+ after standard IC. These results suggest that the expression of CD25 can be used to predict the response to IC during an early period of treatment.