Effects of dietary starch types on early postmortem muscle energy metabolism in finishing pigs

This study aimed to investigate the effects of different dietary starch types on early postmortem muscle energy metabolism in finishing pigs. Ninety barrows (68.0±2.0kg) were randomly allotted to three experimental diets with five replicates of six pigs, containing pure waxy maize starch (WMS), nonwaxy maize starch (NMS), and pea starch (PS) (amylose/amylopectin were 0.07, 0.19 and 0.28 respectively). Compared with the WMS diet, pigs fed the PS diet exhibited greater creatine kinase activity, higher adenosine triphosphate and adenosine diphosphate contents, lower phosphocreatine (PCr), adenosine monophosphate and glycogen contents, and lower glycolytic potential (P<0.05). Moreover, the PS diet led to reduced percentage of bound hexokinase activity, decreased level of phosphorylated AKT (P<0.05) and increased level of hypoxia-inducible factor-1α (P<0.05). In conclusion, diet with high amylose content might promote PCr degradation and inhibit the rate of glycolysis, followed by attenuation of early postmortem glycolysis in finishing pigs.

Silver ion-induced mitochondrial dysfunction via a nonspecific pathway

Silver, once regarded as a safe noble metal for humans, has been widely used in industrial and commercial products, especially in nanometer biomaterials. It is now well known that Ag+ is biologically active and is able to interact with the cell membrane, proteins and DNA. However, very little is understood about the potential impacts of Ag+ at the sub-cellular level. Our work investigated the potential toxicity of Ag+ on mitochondria isolated from rat livers by examining the mitochondrial morphology, respiration, swelling, membrane fluidity and reactive oxygen species (ROS) generation. We observed that Ag+ significantly affects the mitochondrial structure and function, including mitochondrial swelling, collapse of the transmembrane potential, change of permeability and fluidity, decline of the respiratory rate, and acceleration of ROS, indicating that Ag+ should be seriously regarded as a potentially hazardous substance. Moreover, we conclude that Ag+ injures the mitochondrial structure and function by a nonspecific approach, in which the interaction is unregulated by inherent parts such as the mitochondria permeability transition pore (MPTP). These results help us learn more about the toxicity of Ag+ at the subcellular (mitochondrial) level and influence future biological and medical applications of Ag-based materials.

SOX4 Promotes Proliferative Signals by Regulating Glycolysis through AKT Activation in Melanoma Cells

The sex-determining region Y-related high-mobility group box transcription factor 4 (SOX4) plays a fundamental role during embryogenesis and controls cell fate and differentiation. Recently, increased SOX4 expression has been reported in various cancer types, contributing to the progression and survival of cancer cells. However, the distinct functions and downstream targets of SOX4 remain to be fully elucidated. In this study, we initially found elevated SOX4 expression in melanoma. SOX4 regulates apoptosis and cell cycle arrest, affects glucose consumption and lactate production, and consequently, promotes melanoma cell proliferation. Moreover, we found that SOX4 rewires glucose metabolism by regulating the expression of glucose transporter type 1, hexokinase 2, and lactate dehydrogenase A at the transcriptional level. Mechanistically, SOX4 knockdown reduced activation of acutely transforming retrovirus AKT8 in rodent T-cell lymphoma and mTORC1, leading to an attenuated malignant phenotype. We also identified p70 ribosomal S6 kinase and eukaryotic initiation factor 4E-binding protein 1 as key substrates involved in the regulation of mTORC1 in melanoma cells. In conclusion, our study demonstrates the essential role of SOX4 in melanoma glycolytic metabolism through the acutely transforming retrovirus AKT8 in rodent T-cell lymphoma signaling pathway and highlights its potential as a therapeutic target in melanoma management.

BIK is involved in BRAF/MEK inhibitor induced apoptosis in melanoma cell lines

In patients with BRAF-mutated melanoma specific inhibitors of BRAF^V600E and MEK1/2 frequently induce initial tumor reduction, frequently followed by relapse. As demonstrated previously, BRAF^V600E-inhibition induces apoptosis only in a fraction of treated cells, while the remaining arrest and survive providing a source or a niche for relapse. To identify factors contributing to the differential initial response towards BRAF/MEK inhibition, we established M14 melanoma cell line-derived single cell clones responding to treatment with BRAF inhibitor vemurafenib and MEK inhibitor trametinib predominantly with either cell cycle arrest (CCA-cells) or apoptosis (A-cells). Screening for differentially expressed apoptosis-related genes revealed loss of BCL2-Interacting Killer (BIK) mRNA in CCA-cells. Importantly, ectopic expression of BIK in CCA-cells resulted in increased apoptosis rates following vemurafenib/trametinib treatment, while knockdown/knockout of BIK in A-cells attenuated the apoptotic response. Furthermore, we demonstrate reversible epigenetic silencing of BIK mRNA expression in CCA-cells. Importantly, HDAC inhibitor treatment associated with re-expression of BIK augmented sensitivity of CCA-cells towards vemurafenib/trametinib treatment both in vitro and in vivo. In conclusion, our results suggest that BIK can be a critical mediator of melanoma cell fate determination in response to MAPK pathway inhibition.

Multiple pro-tumorigenic functions of the human minor Histocompatibility Antigen-1 (HA-1) in melanoma progression

BACKGROUND

Remodeling of cytoskeleton plays an important role in development of multiple cancers, including melanoma. As a group of F-actin regulators, the Ras homology (Rho) GTPase-activating proteins (ARHGAPs) were reported by accumulating studies as a set of significant mediators in cell morphology, proliferation, migration and invasion.

OBJECTIVE

To investigate the function of HMHA1 and its encode protein HA-1 in melanoma.

METHODS

The mRNA microarray was performed to screen the expression of ARHGAP family genes between melanoma tissues and nevi tissues. QRT-PCR and Western Blot were used to detect the expression of mRNA of HMHA1 and its relevant protein HA-1 respectively. Small interfering RNA was used to knock down the expression of HMHA1. Cell-count kit 8 assays and colony formation assays were used to evaluate the cell proliferative viability of melanoma cells. Flow cytometry was employed to analyze cell apoptosis. Transwell assay and the observation of cell morphology were used to evaluate the invasive and migrating activity of melanoma cells.

RESULTS

In previous study, we first found that both the mRNA level of HMHA1and the expression of HA-1 were up-regulated in melanoma tissues and cell lines compared with nevi tissues and normal human melanocytes respectively. Blocking HMHA1 expression in melanoma cell lines WM35 and A375 suppressed their proliferation and function of colony forming. Moreover, silencing HMHA1 not only significantly increased cell apoptosis but also suppressed cell migration and invasion.

CONCLUSION

Our results demonstrate that HMHA1 significantly promotes melanoma cells proliferation, invasion and migration, and prevents cell apoptosis. Additionally, it can be considered as a new diagnostic marker and drug target of melanoma.

Abstract 477: Down-regulated miR-23a contributes to invasion and metastasis of cutaneous melanoma by promoting autophagy

Background: The occurrence of invasion and metastasis is the major cause of mortality in melanoma. Recent studies suggest that dysregulated miRNAs play critical roles in this procedure, but the underlying mechanism remains elusive. Here, we show that down-regulated miR-23a can promote invasion-metastasis cascade through autophagy in melanoma.Methods: The role of miR-23a in prognosis was assessed in a cohort of melanoma patients (n = 192) with Kaplan-Meier analysis. The effects of miR-23a overexpression were investigated using assays of invasion, migration and in a xenograft model (n = 10 mice per group). Autophagy-related target of miR-23a was confirmed by bioinformatics analysis, luciferase assays and immunoblotting. Molecular studies were performed to determine the downstream cellular and molecular mechanisms. All statistical tests were two-sided.Results: Serum miR-23a level was significantly down-regulated in melanoma patients (P&lt; .001) and was highly correlated with poor clinical outcomes (P = .027, log-rank test). In addition, miR-23a level was remarkably decreased in metastatic melanoma tissues and cell lines (P&lt;.05, P&lt;.01). Moreover, miR-23a overexpression prevented the invasion and migration in vitro and lung and liver metastasis in vivo (both P&lt; .05), by targeting ATG12 and inhibiting autophagy. Mechanically, miR-23a-ATG12 axis attenuated invasion and migration through autophagy-mediated AMPK-RhoA pathway. Finally, the down-regulation of miR-23a in metastatic melanoma was caused by RUNX2 in a transcriptional repression-manner. Conclusion: MiR-23a can act as a crucial epigenetic repressor of melanoma invasion and metastasis in an autophagy-dependent way, which indicates that miR-23a-mediated autophagy inhibition can be exploited to restrain invasion-metastasis cascade in melanoma treatment.

Note: This abstract was not presented at the meeting.

Citation Format: Weinan Guo, Huina Wang, Yuqi Yang, Sen Guo, Weigang Zhang, Tao Zhao, Lin Liu, Zhe Jian, Ling Liu, Gang Wang, Tianwen Gao, Qiong Shi, Chunying Li. Down-regulated miR-23a contributes to invasion and metastasis of cutaneous melanoma by promoting autophagy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 477. doi:10.1158/1538-7445.AM2017-477

Dynamics of fully nonlinear capillary-gravity solitary waves under normal electric fields

Two-dimensional capillary-gravity waves travelling under the effect of a vertical electric field are considered. The fluid is assumed to be a dielectric of infinite depth. It is bounded above by another fluid which is hydrodynamically passive and perfectly conducting. The problem is solved numerically by time-dependent conformal mapping methods. Fully nonlinear waves are presented, and their stability and dynamics are studied.

Down-regulated miR-23a Contributes to the Metastasis of Cutaneous Melanoma by Promoting Autophagy

Melanoma is among the most aggressive tumors, and the occurrence of metastasis leads to a precipitous drop in the patients' survival. Therefore, identification of metastasis-associated biomarkers and therapeutic targets will contribute a lot to improving melanoma theranostics. Recently, microRNAs (miRNAs) have been implicated in modulating cancer invasion and metastasis, and are proved as potential non-invasive biomarkers in sera for various tumors. Here, we reported miR-23a as a novel metastasis-associated miRNA that played a remarkable role in modulating melanoma invasive and metastatic capacity and was of great value in predicting melanoma metastasis and prognosis. We found that serum miR-23a level was significantly down-regulated in metastatic melanoma patients and highly correlated with poor clinical outcomes. In addition, miR-23a level was also remarkably decreased in metastatic melanoma tissues and cell lines. Furthermore, overexpressed miR-23a suppressed the invasive and migratory property of melanoma cells by abrogating autophagy through directly targeting ATG12. Specially, miR-23a-ATG12 axis attenuated melanoma invasion and migration through autophagy-mediated AMPK-RhoA pathway. Finally, the overexpression of miR-23a prevented melanoma metastasis in vivo. Taken together, our findings demonstrate that the metastasis-associated miR-23a is not only a potential biomarker, but also a valuable therapeutic target for melanoma.

A similar local immune and oxidative stress phenotype in vitiligo and halo nevus

BACKGROUND

Vitiligo and halo nevus are two common T-cell-mediated skin disorders. Although autoimmunity has been suggested to be involved in both diseases, the relationship between vitiligo and halo nevus is not fully understood.

OBJECTIVE

The aim of the current study was to investigate whether vitiligo and halo nevus share the same immunological and oxidative stress response.

METHODS

Infiltrations of T cells, and expressions of chemokine receptors (CXCR3, CCR4, CCR5) and cytotoxic markers (Granzyme B, Perforin) in the lesions of vitiligo and halo nevus were examined by immunohistochemistry. Enzyme-linked immunosorbent assay was performed to analyze the expressions of chemokines in the serum samples and cytotoxic markers secreted by CD8⁺ T cells which were sorted from the peripheral blood mononuclear cells in healthy donors, vitiligo and halo nevus patients. Tissue levels of chemokine receptors and CXCR3 ligands in healthy controls, vitiligo patients and halo nevus patients were determined by qRT-PCR analysis. The percentages of CXCR3⁺ CD4⁺ T and CXCR3⁺ CD8⁺ T cells from the peripheral blood samples were examined by flow cytometry. Tissue and serum hydrogen peroxide (H₂O₂) concentrations were measured using H₂O₂ assay kit.

RESULTS

Immunohistochemistry revealed a significant T-cell response, with pronounced dermal infiltrates of CD8⁺ T cells in vitiligo and halo nevus. The inflammatory cytotoxic markers such as Granzyme B and Perforin were also elevated in vitiligo and halo nevus, suggesting inflammatory responses in situ. By qRT-PCR and ELISA assay, we found significantly increased expressions of the chemokine receptor CXCR3 and its ligands, especially the accumulated CXCL10 in the skin lesions of vitiligo and halo nevus. Moreover, the level of H₂O₂, a key player involved in regulation of the immune response was significantly upregulated in the skin lesions of vitiligo and halo nevus. In addition, the increased H₂O₂ concentration correlated positively with CXCL10 level in skin lesions of vitiligo and halo nevus.

CONCLUSIONS

These results demonstrate a H₂O₂-involved autoimmune phenotype in vitiligo and halo nevus, characterized by increased level of IFN-γ-inducible chemokine pair CXCL10-CXCR3, as well as a dense CD8⁺ T infiltration in the skin lesions, thus suggesting a similar pathogenesis of the two diseases.

Dysregulated autophagy increased melanocyte sensitivity to H2O2-induced oxidative stress in vitiligo

In vitiligo, melanocytes are particularly vulnerable to oxidative stress owing to the pro-oxidant state generated during melanin synthesis and to the genetic antioxidant defects. Autophagy is a controlled self-digestion process which can protect cells against oxidative damage. However, the exact role of autophagy in vitiligo melanocytes in response to oxidative stress and the mechanism involved are still not clear. To determine the implications of autophagy for melanocyte survival in response to oxidative stress, we first detected the autophagic flux in normal melanocytes exposure to H₂O₂, and found that autophagy was significantly enhanced in normal melanocytes, for protecting cells against H₂O₂-induced oxidative damage. Nevertheless, vitiligo melanocytes exhibited dysregulated autophagy and hypersensitivity to H₂O₂-induced oxidative injury. In addition, we confirmed that the impairment of Nrf2-p62 pathway is responsible for the defects of autophagy in vitiligo melanocytes. Noteworthily, upregulation of the Nrf2-p62 pathway or p62 reduced H₂O₂-induced oxidative damage of vitiligo melanocytes. Therefore, our data demonstrated that dysregulated autophagy owing to the impairment of Nrf2-p62 pathway increase the sensitivity of vitiligo melanocytes to oxidative stress, thus promote the development of vitiligo. Upregulation of p62-dependent autophagy may be applied to vitiligo treatment in the future.

Simvastatin Protects Human Melanocytes from H2O2-Induced Oxidative Stress by Activating Nrf2

The prevention of hydrogen peroxide (H₂O₂)-induced oxidative stress has proved to be beneficial to vitiligo patients. Simvastatin possesses antioxidative capacity and has shown protective effect in various oxidative stress-related diseases. However, whether simvastatin can protect human melanocytes against oxidative stress has not been investigated. In this study, we initially found that pretreatment with 0.1 μmol/L to 1.0 μmol/L simvastatin led to increased cell viability and decreased cell apoptosis of melanocytes in response to H₂O₂. In addition, simvastatin was able to potentiate the activity of antioxidant enzymes and lessen intracellular reactive oxygen species accumulation. Furthermore, we found that simvastatin promoted the activation of nuclear erythroid 2-related factor (Nrf2) and that knockdown of Nrf2 abolished the protective effect of simvastatin against H₂O₂-induced oxidative damage. More importantly, the mutual enhancement between mitogen-activated protein kinase pathways and p62 contributed to simvastatin-induced Nrf2 activation in melanocytes. Finally, simvastatin showed more antioxidative capacity and better protective effect than aspirin in H₂O₂-treated melanocytes. Taken together, our results show that simvastatin protects human melanocytes from H₂O₂-induced oxidative stress by activating Nrf2, thus supporting simvastatin as a potential therapeutic agent for vitiligo.