Cisplatin-mediated c-myc overexpression and cytochrome c (cyt c) release result in the up-regulation of the death receptors DR4 and DR5 and the activation of caspase 3 and caspase 9, likely responsible for the TRAIL-sensitizing effect of cisplatin

A look into DGAT1 through the EM lenses

With the advent of modern detectors and robust structure solution pipeline, cryogenic electron microscopy has recently proved to be game changer in structural biology. Membrane proteins are challenging targets for structural biologists. This minireview focuses a membrane embedded triglyceride synthesizing machine, DGAT1. Decades of research had built the foundational knowledge on this enzyme's activity. However, recently solved cryo-EM structures of this enzyme, in apo and bound form, has provided critical mechanistic insights. The flipping of the catalytic histidine is critical of enzyme catalysis. The structures explain why the enzyme has preference to long fatty acyl chains over the short forms.

Evodiamine inhibits stemness and metastasis by altering the SOX9-β-catenin axis in non-small-cell lung cancer

Evodiamine (EVO), a natural dietary alkaloid extracted from the roots of the Evodia rutaecarpa, has shown anticancer activities. Here, we have investigated EVO's role in inhibiting cell proliferation and migration in A549 and NCI-H522 lung cancer cells. EVO decreased the cell viability in A549 and NCI-H522 cells in a dose- and time-dependent manner. It also induced apoptosis by downregulating the expression of antiapoptotic Bcl-2 and upregulating the expression of cleaved caspase-3 and PARP. In addition, the treatment of EVO elevated the level of reactive oxygen species (ROS) generation inside the cells to induce the cell death pathways. In contrast, the pretreatment of ROS scavenger, N-acetyl cysteine, reverses the effect of EVO and attenuates cell death. Moreover, excess ROS generation in response to EVO resulted in the depletion of mitochondrial membrane potential. Furthermore, it induced DNA damage and arrested the cell cycle at the G2/M phase in A549 and NCI-H522 cells. Our study also investigated that EVO significantly suppressed tumorigenicity by inhibiting colony formation and tumorsphere formation. However, the treatment of EVO downregulated the cancer stem cell markers CD44 and CD133 in non-small-cell lung cancer. The inhibitory effect of EVO on cell invasion was mediated by altering the expression of E-cadherin, ZO-1, N-cadherin, and Vimentin. Additionally, we have revealed that EVO treatment showed downregulation of SOX9, an upstream component of β-catenin. Lastly, we have demonstrated that EVO targets the SOX9-β-catenin axis by reducing SOX9 and β-catenin expression. These findings suggested that EVO could be a promising agent for treating human lung cancer.

Unbalanced ER-mitochondrial calcium homeostasis promotes mitochondrial dysfunction and associated apoptotic pathways activation in methylmercury exposed rat cortical neurons

Methylmercury (MeHg) is a cumulative environmental pollutant that can easily cross the blood-brain barrier and cause damage to the brain, mainly targeting the central nervous system. The purpose of this study is to investigate the role of calcium ion (Ca²⁺ ) homeostasis between the endoplasmic reticulum (ER) and mitochondria in MeHg-induced neurotoxicity. Rat primary cortical neurons exposed to MeHg (0.25-1 μm) underwent dose-dependent cell damage, accompanied by increased Ca²⁺ release from the ER and elevated levels of free Ca²⁺ in cytoplasm and mitochondria. MeHg also increased the protein and messenger RNA expressions of the inositol 1,4,5-triphosphate receptor, ryanodine receptor 2, and mitochondrial calcium uniporter. Ca²⁺ channel inhibitors 2-aminoethyl diphenylborinate and procaine reduced the release of Ca²⁺ from ER, while RR and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate inhibited Ca²⁺ uptake from mitochondria. In addition, pretreatment with Ca²⁺ chelator BAPTA-AM effectively restored mitochondrial membrane potential levels, inhibited over opening of mitochondrial permeability transition pore, and maintained mitochondrial function stability. Meanwhile, the expression of mitochondrial apoptosis-related proteins recovered to some extent, along with the reduction of the early apoptosis ratio. These results suggest that Ca²⁺ homeostasis plays an essential role in mitochondrial damage and apoptosis induced by MeHg, which may be one of the important mechanisms of MeHg-induced neurotoxicity.

Chemo-Sensitization of CD133+ Cancer Stem Cell Enhances the Effect of Mesenchymal Stem Cell Expressing TRAIL in Non-Small Cell Lung Cancer Cell Lines

Simple Summary

The anti-tumor properties of mesenchymal stem cell (MSCs) expressing TNF-related apoptosis inducing ligand (TRAIL) or MSC-TRAIL have been well documented by several reports. However, some tumors are resistant to TRAIL due to the existence of cancer stem cells (CSCs). Chemo-sensitization of tumors and their CSCs has been reported to enhance TRAIL-mediated inhibition. In this study, we examined the effect of pre-treatment using first-line chemotherapies on MSC-TRAIL-induced inhibition in non-small cell lung cancers (NSCLCs)–derived CSCs. We found that these chemotherapies were able to induce a chemo-sensitization effect to the CSC, thus improving the MSC-TRAIL-induced inhibition. We also noticed that the effect of chemo-sensitization was cell type specific and selecting chemotherapies for the right NSCLC subtypes might help in inducing a more meaningful combinatory effect. As such, this study has proven that chemo-sensitization of the CSCs was able to enhance the MSC-TRAIL-induced inhibition in NSCLC cell lines.

Abstract

Pre-clinical studies have demonstrated the efficacy of mesenchymal stem cells (MSCs) expressing tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) or MSC-TRAIL against several tumors. However, due to the existence of cancer stem cells (CSCs), some tumors, including non-small cell lung cancer (NSCLC), exhibit TRAIL resistance. This study was designed to evaluate the capacity of using first-line chemotherapies including cisplatin, 5-fluorouracil (5-FU) and vinorelbine to act as a chemo-sensitizer on CD133+ (prominin-1 positive) CSCs derived from NSCLC cell lines (A549, H460 and H2170) for the purpose of MSC-TRAIL-induced inhibition. We showed that MSC-TRAIL was resistant to all three chemotherapies compared to the NSCLC cell lines, suggesting that the chemotherapies had little effect on MSC-TRAIL viability. Pre-treatment using either cisplatin or 5-FU, but not with vinorelbine, was able to increase the efficacy of MSC-TRAIL to kill the TRAIL-resistant A549-derived CSCs. The study also demonstrated that both 5-FU and vinorelbine were an effective chemo-sensitizer, used to increase the anti-tumor effect of MSC-TRAIL against H460- and H2170-derived CSCs. Furthermore, pre-treatment using cisplatin was noted to enhance the effect of MSC-TRAIL in H460-derived CSCs; however, this effect was not detected in the H2170-derived CSCs. These findings suggest that a pre-treatment using certain chemotherapies in NSCLC could enhance the anti-tumor effect of MSC-TRAIL to target the CSCs, and therefore the combination of chemotherapies and MSC-TRAIL may serve as a novel approach for the treatment of NSCLC.

Peripheral Membrane Proteins: Promising Therapeutic Targets across Domains of Life

Membrane proteins can be classified into two main categories-integral and peripheral membrane proteins-depending on the nature of their membrane interaction. Peripheral membrane proteins are highly unique amphipathic proteins that interact with the membrane indirectly, using electrostatic or hydrophobic interactions, or directly, using hydrophobic tails or GPI-anchors. The nature of this interaction not only influences the location of the protein in the cell, but also the function. In addition to their unique relationship with the cell membrane, peripheral membrane proteins often play a key role in the development of human diseases such as African sleeping sickness, cancer, and atherosclerosis. This review will discuss the membrane interaction and role of periplasmic nitrate reductase, CymA, cytochrome c, alkaline phosphatase, ecto-5'-nucleotidase, acetylcholinesterase, alternative oxidase, type-II NADH dehydrogenase, and dihydroorotate dehydrogenase in certain diseases. The study of these proteins will give new insights into their function and structure, and may ultimately lead to ground-breaking advances in the treatment of severe diseases.

Synergistic anticancer effect of docosahexaenoic acid and isoliquiritigenin on human colorectal cancer cells through ROS-mediated regulation of the JNK and cytochrome c release

A large body of research has demonstrated a synergistic anticancer effect between docosahexaenoic acid (DHA) and standard chemotherapy regimens against colorectal cancer (CRC). In this study, we investigated the chemotherapeutic potential of cotreatment with DHA and isoliquiritigenin (ISL) against CRC HCT-116 cells. Apoptosis was confirmed by Annexin V/PI staining and expression of apoptosis-associated proteins. The synergistic effect of DHA and ISL combination on apoptosis was detected using combination index approaches. Flow cytometry was carried out using fluorescent probes to measure the production of reactive oxygen species (ROS). DHA and ISL in combination synergistically enhanced the decrease in cell viability versus the compounds used alone. Moreover, we demonstrated that the synergistic anti-CRC activity of cotreatment with these two compounds was achieved by inducing the apoptosis caspase-dependently mediated through augmented ROS generation followed by increased Fas ligand mRNA expression and cytochrome c release. Our data also demonstrated that cotreating with DHA and ISL strongly upregulated the phosphorylation of ERK and JNK, which are functionally associated with ROS induced by the two compounds in combination. Interestingly, further study revealed that inhibiting ERK phosphorylation strongly enhanced Fas ligand mRNA expression and the combination of the two compounds induced stronger cytotoxicity, whereas inhibiting JNK phosphorylation significantly reduced the apoptotic signals mediated by cotreatment with these two compounds. Excessive ROS-induced JNK activation and cytochrome c release from mitochondria played a key role in the synergistic anticancer activity of CRC cells by cotreating with DHA and ISL.

Exosomes derived from RPE cells under oxidative stress mediate inflammation and apoptosis of normal RPE cells through Apaf1/caspase-9 axis

This study aims to explore the effects of exosomes, secreted by retinal pigment epithelial (RPE) cells under oxidative stress (OS), on apoptosis and inflammation of normal RPE cells. Exosomes secreted by normal RPE cells (named as exo) and rotenone (2.5 µmol/L) stimulated RPE cells (named as rot-exo) were isolated and extracted by multi-step differential centrifugation for morphology observation under a transmission electron microscopy. pcDNA3.1a, pcDNA3.1a-Apaf1, and p3xFlag-CMV-caspase-9 plasmids were constructed and transfected into ARPE-19 cells. Exosomes secreted by ARPE-19 cells were injected into the vitreous body of rats to verify the effect of Apaf1 and caspase-9 on cell apoptosis and inflammation. Co-immunoprecipitation was applied to clarify the interaction of Apaf1 with caspase-9. Exosomes secreted by rotenone stimulated ARPE-19 cells could induce cell apoptosis, oxidative injury, and inflammation in ARPE-19 cells. Exosomes secreted under OS can damage retinal functions of rats and have upregulated expression of Apaf1. Overexpression of Apaf1 in exosomes secreted under OS can cause the inhibition of cell proliferation, the increase of cell apoptosis and elicitation of inflammatory response in ARPE-19 cells. Exosomes derived from ARPE-19 cells under OS regulate Apaf1 expression to increase cell apoptosis and to induce oxidative injury and inflammatory response through a caspase-9 apoptotic pathway.

Construction of biomimetic silver nanoparticles in the treatment of lymphoma

Lymphoma is a well-known malignant tumor in the human body. Although many anticancer drugs have been developed to improve the survival rate of patients, about 40% of patients continue to be recurrent or refractory, a key issue needing remedy. Therefore, it is necessary to identify alternative treatments to reduce the disease's mortality. To this effect, a new type of anti-lymphoma nanocomplex FA@RBCm-AgNPs was prepared using AgNPs as the core of nanoparticles along with the targeting molecule folic acid inserted erythrocyte membrane as the shell. The biomimetic properties of red blood cell membrane (RBCm) endow F-RAN with good biocompatibility as well as the ability to evade clearance of the reticuloendothelial system. In addition, F-RAN was modified with folic acid to actively and selectively identify tumor cells. In vivo and in vitro experiments demonstrate that F-RAN can inhibit lymphoma cells and induce apoptosis of stem cells while promoting apoptosis of lymphoma with no obvious side effects. Hence, F-RAN may serve as a new treatment for lymphoma.

PIM1 inhibitor synergizes the anti-tumor effect of osimertinib via STAT3 dephosphorylation in EGFR-mutant non-small cell lung cancer

Background

An increasing amount of evidence has demonstrated that combined or multiple targeted therapies could bring about more durable clinical outcomes, and it is known that epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance is related to bypass activation. This study aims to explore a specific solution for third-generation EGFR-TKI resistance caused by bypass activation, and to examine the antitumor effects of the combination of a novel inhibitor CX-6258 HCl with osimertinib, along with its underlining mechanisms.

Methods

A bioinformatics analysis was performed to detect the relations between the provirus integration site for Moloney murine leukemia virus 1 (PIM1) expression and prognosis of lung cancer. The EGFR-mutated lung cancer cell lines were treated with the combination of CX-6258 HCl and osimertinib to analyze cell proliferation using the Cell Counting Kit-8, colony formation, and in vivo experiments. Cell migration was analyzed using wound healing and Transwell assays. The apoptosis level was detected using Annexin V-propidium iodide flow cytometry. The expression levels of EGFR and STAT3 were determined using Western blot analysis.

Results

High expression level of PIM1 was related to the poor prognosis of non-small cell lung cancer (NSCLC). The combined administration of osimertinib and CX-6258 HCl significantly inhibited cell proliferation and migration and effectively induced apoptosis in lung cancer cells. It was more efficient in suppressing EGFR activation and phosphorylation of STAT3 compared with osimertinib treatment alone. Furthermore, it showed a durable efficacy in a xenograft model.

Conclusions

This study showed that PIM1 is a poor prognostic factor for NSCLC. CX-6258 HCl is a potential molecular inhibitor to sensitize the antitumor effects of osimertinib through the inhibiting of the phosphorylation of STAT3 in NSCLC.

TRAIL in oncology: From recombinant TRAIL to nano- and self-targeted TRAIL-based therapies

TNF-related apoptosis-inducing ligand (TRAIL) selectively induces the apoptosis pathway in tumor cells leading to tumor cell death. Because TRAIL induction can kill tumor cells, cancer researchers have developed many agents to target TRAIL and some of these agents have entered clinical trials in oncology. Unfortunately, these trials have failed for many reasons, including drug resistance, off-target toxicities, short half-life, and specifically in gene therapy due to the limited uptake of TRAIL genes by cancer cells. To address these drawbacks, translational researchers have utilized drug delivery platforms. Although, these platforms can improve TRAIL-based therapies, they are unable to sufficiently translate the full potential of TRAIL-targeting to clinically viable products. Herein, we first summarize the complex biology of TRAIL signaling, including TRAILs cross-talk with other signaling pathways and immune cells. Next, we focus on known resistant mechanisms to TRAIL-based therapies. Then, we discuss how nano-formulation has the potential to enhance the therapeutic efficacy of TRAIL protein. Finally, we specify strategies with the potential to overcome the challenges that cannot be addressed via nanotechnology alone, including the alternative methods of TRAIL-expressing circulating cells, tumor-targeting bacteria, viruses, and exosomes.

Astragalus Polysaccharide Attenuates Cisplatin-Induced Acute Kidney Injury by Suppressing Oxidative Damage and Mitochondrial Dysfunction

Cisplatin is a widely used chemotherapeutic drug in the treatment of various solid tumors. However, the cisplatin-induced acute kidney injury remains a disturbing complication, which still lacks effective prevention. Cisplatin-induced oxidative damage and mitochondrial dysfunction are anticipated to be crucial in the occurrence of kidney injury. Astragalus polysaccharide (APS) has been reported to possess multiple biological activities including anti-inflammatory, antioxidant, and mitochondria protection. In this study, we investigated the potentially protective effect of APS against cisplatin-induced kidney injury both in vivo and in vitro. We found that APS pretreatment attenuated the cisplatin-induced renal dysfunction and histopathological damage in mice; in addition, it also protected the viability of HK-2 cells upon cisplatin exposure. APS attenuated the cisplatin-induced oxidative damage by reducing reactive oxygen species (ROS) generation and recovering the activities of total superoxide dismutase and glutathione peroxidase in mice kidney. In addition, electron microscope analysis indicated that cisplatin induced extensive mitochondrial vacuolization in mice kidney. However, APS administration reversed these mitochondrial morphology changes. In HK-2 cells, APS reduced the cisplatin-induced mitochondrial and intracellular ROS generation. Furthermore, APS protected the normal morphology of mitochondria, blocked the cisplatin-induced mitochondrial permeability transition pore opening, and reduced the cytochrome c leakage. Subsequently, APS reduced the cisplatin-induced apoptosis in mice renal and HK-2 cells. In conclusion, our data suggested that APS pretreatment might prevent cisplatin-induced kidney injury through attenuating oxidative damage, protecting mitochondria, and ameliorating mitochondrial-mediated apoptosis.

Effects of Serum Cytochrome c on Contrast-Induced Nephropathy in Patients with ST-Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Background and Aims

Contrast-induced nephropathy (CIN) is a relatively infrequent complication after percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI). However, little is known about the association between cytochrome c (cyt c) and increased risk of CIN. We conducted this study to explore the impact of serum cyt c on the occurrence of CIN.

Methods

We prospectively examined cyt c levels before undergoing PCI in 240 patients with STEMI. The logistic regression was performed to identify the independent risk factors for the occurrence of CIN. The receiver operating characteristic (ROC) analysis was employed to evaluate the predictive value of cyt c for the occurrence of CIN.

Results

29 patients (12.1%) had developed CIN after the PCI procedure. The cyt c levels at baseline were significantly higher in patients who developed CIN than those in non-CIN group (0.65±0.08 versus 0.58±0.1; P = 0.001). The multivariate logistic regression showed that cyt c was an independent risk factor for the occurrence of CIN (OR, 7.421; 95% CI, 6.471–20.741; P = 0.034) after adjusting for age, history of hypertension and diabetes mellitus, levels of creatinine, uric acid, and glucose. The ROC curve analysis showed that the area under the curve of cyt c was 0.697 (95% CI, 0.611–0.783; P = 0.001), and cyt c > 0.605 ng/mL predicted CIN with sensitivity of 79.3% and specificity of 56.9%.

Conclusion

Our results show that a higher cyt c level was significantly associated with the occurrence of CIN after PCI in STEMI patients. This study has been registered in the Chinese Clinical Trial Registry. The clinical trial registration number is ChiCTR1800019368.

miR-34a increases cisplatin sensitivity of osteosarcoma cells in vitro through up-regulation of c-Myc and Bim signal

BACKGROUND AND OBJECTIVE

Osteosarcoma is the most common primary malignancy in bone. Patients who respond poorly to induction chemotherapy are at higher risk of adverse prognosis. The molecular basis for such poor prognosis remains unclear. Recently, increasing evidence has suggested decreased expression of miR-34a is observed in a number of cancer types, including human osteosarcoma, and decreased miR-34a is involved in drug resistance. However, the underlying molecular mechanisms of decreased miR-34a on cisplatin chemoresistance in osteosarcoma has not been reported.

METHODS

Osteosarcoma U2OS cells were transfected with miR-34a mimics for 48 h, then the cells were treated with 3.0 μm cisplatin for 24 h. Using siRNA targeting c-Myc and Bim to examine the relation between miR-34a, c-Myc and Bim expression exposure to cisplatin on cisplatin-induced apoptosis.

RESULTS

Treatment of U2OS cells with cisplatin induced cell apoptosis by upregulation of c-Myc -dependent Bim expression; Osteosarcoma U2OS cells transfected with miR-34a mimics (miR-34a/U2OS) induced cell apoptosis and inhibited cell survival, and increased the sensitivity of U2OS cells to cisplatin. U2OS cells transfected with miR-34a mimics upregulated the protein expression of c-Myc and Bim. Targeting c-Myc downregulated the expression of Bim in the miR-34a/U2OS cells. In addition, Targeting Bim reversed the chemeresistance of miR-34a/U2OS cells to cisplatin.

CONCLUSIONS

Our data indicated that miR-34a enhanced the sensitivity to cisplatin by upregulation of c-Myc and Bim pathway.

Pachymic acid inhibits growth and induces cell cycle arrest and apoptosis in gastric cancer SGC-7901 cells

The aim of the present study was to elucidate the anticancer effect of pachymic acid (PA) in gastric cancer SGC-7901 cells and the potential molecular mechanisms involved. Cell Count kit-8 assay was performed to examine the effect of PA on the cell proliferation of SGC-7901 cells. Cell cycle, cell apoptosis, mitochondria membrane potential (Dψm) and reactive oxygen species (ROS) analysis were assessed by flow cytometry, respectively. DNA fragmentation assay was performed by Hoechst 33258 staining. Western blotting was performed to detect the effect of various concentrations of PA on the levels of BCL2 associated X protein (Bax) expression as well as B-cell lymphoma 2 (Bcl-2), cytochrome C (cyt-c) and caspase-3 in SGC-7901 cells. It was demonstrated that PA was able to significantly inhibit the viability and induce G₀/G₁ cell cycle arrest of SGC-7901 cells in a concentration-dependent manner. The apoptotic rate and ROS generation were markedly increased, while Dψm was decreased following the treatment of SGC-7901 cells with various concentrations of PA. Moreover, the expression of Bax, cytochrome c and caspase-3 were markedly increased and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) was significantly inactivated and BCL-2 expression was decreased following PA treatment in SGC-7901 cells. Notably, JAK2 inhibitor (AG490) mimics the effects of PA on the viability and apoptosis of SGC-7901 cells. Further in vivo study indicated that treatment with PA significantly inhibited the growth of tumor in nude mice that were transplanted with SGC-7901 cells in a concentration-dependent manner. These results may advance the current understanding of the anticancer mechanisms of PA in gastric cancer.

Rosuvastatin relieves myocardial ischemia/reperfusion injury by upregulating PPAR‑γ and UCP2

The present study aimed to investigate whether pretreatment with rosuvastatin (RS) can provide cardioprotection in a myocardial ischemia/reperfusion (MI/R) model. The protective effect of RS on myocardial oxygen-glucose deprivation/reperfusion (OGD/R) injury was also evaluated by upregulating peroxisome proliferator-activated receptor-γ (PPAR-γ). In the present study, MI/R model was established and activities of superoxide dismutase (SOD), lactate dehydrogenase (LDH), creatine kinase-muscle/brain (CK-MB), malondialdehyde (MDA), and troponin I/T were measured. The infarct size was measured using Evans blue staining and cell viability was measured by MTT assay. Reactive oxygen species (ROS) levels were assessed by flow cytometry. Caspase-9, cytochrome c (cyt c), mitochondrial uncoupling protein 2 (UCP2) and PPAR-γ expression levels were detected by reverse transcription-quantitative polymerase chain reaction and western blotting. The results indicated that RS increased SOD activity, and decreased LDH, CK-MB, MDA and troponin I/T activities. The effect of RS was reversed by atractyloside (ATR). RS inhibited myocardial infarct size, downregulated expression of caspase-9 and cyt c and upregulated expression of UCP2 and PPAR-γ by inhibiting ATR. Furthermore, the results indicated that RS promoted cardiomyocyte viability, inhibited LDH release, reduced ROS production, decreased expression of caspase-9 and cyt c, and increased expression of UCP2 and PPAR-γ following OGD/R damage. Therefore, the present study demonstrated that RS protects primary myocardial cells against OGD/R injury by regulating PPAR-γ and UCP2. RS may be a promising therapeutic agent for treatment of MI/R injury.

miR-135a promotes gastric cancer progression and resistance to oxaliplatin

Resistance to oxaliplatin (OXA)-based chemotherapy regimens continues to be a major cause of gastric cancer (GC) recurrence and metastasis. We analyzed GC samples and matched non-tumorous control stomach tissues from 280 patients and found that miR-135a was overexpressed in GC samples relative to control tissues. Tumors with high miR-135a expression were more likely to have aggressive characteristics (high levels of carcino-embryonic antigen, vascular invasion, lymphatic metastasis, and poor differentiation) than those with low levels. Patients with greater tumoral expression of miR-135a had shorter overall survival times and times to disease recurrence. Furthermore, miR-135a, which promotes the proliferation and invasion of OXA-resistant GC cells, inhibited E2F transcription factor 1 (E2F1)-induced apoptosis by downregulating E2F1 and Death-associated protein kinase 2 (DAPK2) expression. Our results indicate that higher levels of miR-135a in GC are associated with shorter survival times and reduced times to disease recurrence. The mechanism whereby miR-135a promotes GC pathogenesis appears to be the suppression of E2F1 expression and Sp1/DAPK2 pathway signaling.

Sphingomyelin synthase 2 overexpression promotes cisplatin-induced apoptosis of HepG2 cells

Hepatoblastoma (HB) is the most type of common pediatric liver cancer. The primary chemotherapy drug for HB is cisplatin (DDP). However, patients readily develop intrinsic and acquired resistance, and severe side effects to treatment. Sphingomyelin synthase 2 (SMS2) is a key enzyme involved in the generation of sphingomyelin (SM), which is able to regulate cell proliferation, apoptosis and differentiation. The death receptors (DRs) have important functions in DDP-induced apoptosis. However, whether SMS2 is able to modulate cell apoptosis through the DR signaling pathway remains unknown. To investigate this question, SMS2 was overexpressed in HepG2 cells and treated with 3.5 mg/l cisplatin in the present study. After 24 h, the expression of SMS2, avian myelocytomatosis viral oncogene homolog (c-Myc), DR4, DR5 and caspase-3 was analyzed. Furthermore, cell viability was quantified, and apoptosis was assessed by western blot and flow cytometry analysis as well as Cell Counting kit-8. The results of the present study revealed that overexpression of SMS2 was able to increase the expression of c-Myc, cleaved caspase-3, DR4 and DR5 compared with the control group (P<0.05, n=3), and increase the levels of apoptosis in the SMS2 + DDP group, compared with the control (P<0.001, n=3). These results indicate that overexpression of SMS2 is able to improve sensitivity of HepG2 cells to DDP by increasing the expression of c-Myc, DR4 and DR5 in HepG2 cells. This increased sensitivity may decrease intrinsic and acquired resistance of chemotherapy in HB, and reduce the associated severe side effects in pediatric patients.

Modulation of the mRNA-binding protein HuR as a novel reversal mechanism of epirubicin-triggered multidrug resistance in colorectal cancer cells

HuR (ELAVL1), a RNA-binding protein, plays a key role in posttranscriptional regulation of multidrug resistance (MDR)-related genes. Among various HuR-regulated oncogenic transcripts, the activation of galectin-3/β-catenin survival pathway is critical to induce transcription of cyclin D1, P-glycoprotein (P-gp) and/or multidrug resistance-associated proteins (MRPs). In this study, we aim to elucidate the HuR-regulating pathways related to epirubicin-mediated resistance in human colorectal carcinoma cells. The effects and mechanisms of epirubicin treatment on the expressions of upstream survival signals (e.g., β-catenin) and downstream MDR transporters (e.g., P-gp) and anti-apoptotic pathways (e.g., Bcl-2) were assessed with or without HuR knockdown (siHuR) or overexpression (overHuR; ectopic HuR or pcDNA3/HA-HuR). Our results showed that siHuR decreased transcriptional expressions of galectin-3, β-catenin, cyclin D1, Bcl-2, P-gp, MRP1, and MRP2 in epirubicin-treated colon cancer cells. Consistently, the co-treatment of epirubicin and siHuR diminished the expressions of galectin-3, ß-catenin, c-Myc, P-gp and MRP1. HuR silencing enhanced the intracellular accumulation of epirubicin in colon cancer cells. On the other hand, overHuR abolished such effects. Furthermore, siHuR significantly intensified epirubicin-mediated apoptosis via increasing reactive oxygen species and thus promoted the cytotoxic effect of epirubicin. The combined treatments of siHuR and epirubicin significantly reduced the expression of Bcl-2, but increased the expression of Bax, as well as activity and expression levels of caspase-3 and -9. In contrast, overHuR abrogated these effects. Our findings provide insight into the mechanisms by which siHuR potentiated epirubicin-induced cytotoxicity via inhibiting galectin-3/β-catenin signaling, suppressing MDR transporters and provoking apoptosis. To our best knowledge, this is an innovative investigation linking the post-transcriptional control by HuR silencing to survival signaling repression, efflux transporter reversal and apoptosis induction. Our study thus provides a powerful regimen for circumventing MDR in colon cancer cells.

N-myc downstream-regulated gene 1 promotes apoptosis in colorectal cancer via up-regulating death receptor 4

The aim of this study was to evaluate the clinical significance of N-myc downstream-regulated gene 1 (NDRG1) in colorectal cancer (CRC) patients and to explore the mechanisms governing the role of NDRG1 in apoptosis of CRC cells. In the current study, we found that NDRG1 was a prognostic marker of CRC patients. Moreover, NDRG1 expression negatively correlated to tumor size and clinical TNM stage, suggesting that NDRG1 might act as a tumor suppressor by inhibiting proliferation or inducing apoptosis in CRC. Consistently, substantial apoptosis was observed in vitro and in vivo in the presence of NDRG1. From a mechanistic standpoint, we discovered that NDRG1 was able to prevent death receptor 4 from degradation induced by MARCH-8, a member of the membrane-associated RING-CH (MARCH) ubiquitin ligase family. As a consequence, CRC cells expressing NDRG1 were more sensitive to reagents targeting death receptors such as tumor necrosis factor-related apoptosis-inducing ligands (TRAIL). Additionally, the pro-apoptotic effect of NDRG1 was also validated in mouse xenograft model. In conclusion, our results provided further insights of the pivotal role of NDRG1 in apoptosis initiated by death receptors and demonstrated a novel marker to predict the sensitivity of CRC to TRAIL treatment in future clinical study.

Evaluation of the antitumor activity of platinum nanoparticles in the treatment of hepatocellular carcinoma induced in rats

This study aimed to evaluate the antitumor activity of platinum nanoparticles compared with cis-platin both in vitro and in vivo in the treatment of hepatocellular carcinoma induced in rats. The treatment efficacy of platinum nanoparticles was evaluated by measuring antioxidant activities against oxidative stress caused by diethylnitrosamine in liver tissue. The measurements included reduced glutathione content and superoxide dismutase activity, as well as malondialdehyde level. Liver function tests were also determined, in addition to the evaluation of serum alpha-fetoprotein, caspase-3, and cytochrome c in liver tissue. Total RNA extraction from liver tissue samples was also done for the relative quantification of B-cell lymphoma 2, matrix metallopeptidase 9, and tumor protein p53 genes. Histopathological examination was also performed for liver tissue. Results showed that platinum nanoparticles are more potent than cis-platin in treatment of hepatocellular carcinoma induced by diethylnitrosamine in rats as it ameliorated the investigated parameters toward normal control animals. These findings were well appreciated with histopathological studies of diethylnitrosamine group treated with platinum nanoparticles, suggesting that platinum nanoparticles can serve as a good therapeutic agent for the treatment of hepatocellular carcinoma which should attract further studies.

c-Myc Modulation and Acetylation Is a Key HDAC Inhibitor Target in Cancer

Purpose: Histone deacetylase inhibitors (HDACi) are promising anticancer drugs. Although some HDACi have entered the clinic, the mechanism(s) underlying their tumor selectivity are poorly understood.Experimental Design and Results: Using gene expression analysis, we define a core set of six genes commonly regulated in acute myeloid leukemia (AML) blasts and cell lines. MYC, the most prominently modulated, is preferentially altered in leukemia. Upon HDACi treatment, c-Myc is acetylated at lysine 323 and its expression decreases, leading to TRAIL activation and apoptosis. c-Myc binds to the TRAIL promoter on the proximal GC box through SP1 or MIZ1, impairing TRAIL activation. HDACi exposure triggers TRAIL expression, altering c-Myc-TRAIL binding. These events do not occur in normal cells. Excitingly, this inverse correlation between TRAIL and c-Myc is supported by HDACi treatment ex vivo of AML blasts and primary human breast cancer cells. The predictive value of c-Myc to HDACi responsiveness is confirmed in vivo in AML patients undergoing HDACi-based clinical trials.Conclusions: Collectively, our findings identify a key role for c-Myc in TRAIL deregulation and as a biomarker of the anticancer action of HDACi in AML. The potential improved patient stratification could pave the way toward personalized therapies. Clin Cancer Res; 23(10); 2542-55. ©2016 AACR.

Melittin induces human gastric cancer cell apoptosis via activation of mitochondrial pathway

AIM: To investigate the apoptotic effects of melittin on SGC-7901 cells via activation of the mitochondrial signaling pathway in vitro.

METHODS: SGC-7901 cells were stimulated by melittin, and its effect on proliferation and apoptosis of was investigated by methyl thiazolyl tetrazolium assay, morphologic structure with transmission electron microscopy, annexin-V/propidium iodide double-staining assay, measuring mitochondrial membrane potential (MMP) levels, and analyzing reactive oxygen species (ROS) concentrations were analyzed by flow cytometry. Cytochrome C (Cyt C), apoptosis-inducing factor (AIF), endonuclease G (Endo G), second mitochondria-derived activator of caspases (Smac)/direct IAP binding protein with low isoelectric point (Diablo), and FAS were analyzed by western blot. The expression of caspase-3 and caspase-8 was measured using activity assay kits.

RESULTS: Melittin was incubated at 1.0, 2.0, 4.0, or 6.0 μg/mL for 1, 2, 4, 6, or 8 h and showed a time- and concentration-dependent inhibition of SGC-7901 cell growth. Melittin induced SGC-7901 cell apoptosis, which was confirmed by typical morphological changes. Treatment with 4 μg/mL melittin induced early apoptosis of SGC-7901 cells, and the early apoptosis rates were 39.97% ± 3.19%, 59.27% ± 3.94%, and 71.50% ± 2.87% vs 32.63% ± 2.75% for 1, 2, and 4 h vs 0 h (n = 3, P < 0.05); the ROS levels were 616.53% ± 79.78%, 974.81% ± 102.40%, and 1330.94% ± 93.09% vs 603.74% ± 71.99% (n = 3, P < 0.05); the MMP values were 2.07 ± 0.05, 1.78 ± 0.29, and 1.16 ± 0.25 vs 2.55 ± 0.42 (n = 3, P < 0.05); caspase-3 activity was significantly higher compared to the control (5492.3 ± 321.1, 6562.0 ± 381.3, and 8695.7 ± 449.1 vs 2330.0 ± 121.9), but the caspase activity of the non-tumor cell line L-O2 was not different from that of the control. With the addition of the caspase-3 inhibitor (Ac-DEVD-CHO), caspase-3 activity was significantly decreased compared to the control group (1067.0 ± 132.5 U/g vs 8695.7 ± 449.1 U/g). The expression of the Cyt C, Endo G, and AIF proteins in SGC-7901 cells was significantly higher than those in the control (P < 0.05), while the expression of the Smac/Diablo protein was significantly lower than the control group after melittin exposure (P < 0.01). Ac-DEVD-CHO did not, however, have any effect on the expression of caspase-8 and FAS in the SGC-7901 cells.

CONCLUSION: Melittin can induce apoptosis of human gastric cancer (GC) cells through the mitochondria pathways, and it may be a potent agent in the treatment of human GC.

Adiponectin receptor-mediated signaling ameliorates cerebral cell damage and regulates the neurogenesis of neural stem cells at high glucose concentrations: an in vivo and in vitro study

In the central nervous system (CNS), hyperglycemia leads to neuronal damage and cognitive decline. Recent research has focused on revealing alterations in the brain in hyperglycemia and finding therapeutic solutions for alleviating the hyperglycemia-induced cognitive dysfunction. Adiponectin is a protein hormone with a major regulatory role in diabetes and obesity; however, its role in the CNS has not been studied yet. Although the presence of adiponectin receptors has been reported in the CNS, adiponectin receptor-mediated signaling in the CNS has not been investigated. In the present study, we investigated adiponectin receptor (AdipoR)-mediated signaling in vivo using a high-fat diet and in vitro using neural stem cells (NSCs). We showed that AdipoR1 protects cell damage and synaptic dysfunction in the mouse brain in hyperglycemia. At high glucose concentrations in vitro, AdipoR1 regulated the survival of NSCs through the p53/p21 pathway and the proliferation- and differentiation-related factors of NSCs via tailless (TLX). Hence, we suggest that further investigations are necessary to understand the cerebral AdipoR1-mediated signaling in hyperglycemic conditions, because the modulation of AdipoR1 might alleviate hyperglycemia-induced neuropathogenesis.

Correlation between Polymorphism of TRAIL Gene and Condition of Intervertebral Disc Degeneration

Background

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been suggested to be related with the pathogenesis and progression of osteoarticular degenerations. This study therefore aimed to investigate the relationship between the polymorphism of the TRAIL gene and the pathogenesis and severity of intervertebral disc degeneration (IDD) via detection of serum TRAIL expression levels.

Material/Methods

A total of 100 IDD patients in our hospital were recruited in the experimental group, while another cohort of 100 healthy individuals was employed as the control group. Blood samples collected from all people were quantified for TRAIL level using enzyme-linked immunosorbent assay (ELISA), in addition to allele and genotype frequency analysis via fluorescent PCR for TRAIL gene.

Results

At loci 1525 and 1529 in 3′-untranslated region (UTR) of 5^th exon of TRAIL gene, 3 different genotypes were identified: experimental group had higher frequency of 1525CG/1595CC, 1525G and 1595C alleles, compared to the control group (p<0.05). Patients under Schneiderman grade IV had significantly higher allele frequency compared to those at grade II or III. Serum TRAIL level was also higher in the experimental group compared to the control group, and in grade IV patients compared to grade II or III patients (p<0.05).

Conclusions

The G/C mutation at loci 1525/1595 of TRAIL gene may induce the progression of IDD, as the down-regulation of TRAIL can aggravate the severity of the disease.