JS-K as a nitric oxide donor induces apoptosis via the ROS/Ca2+/caspase-mediated mitochondrial pathway in HepG2 cells

Glycyrrhetinic acid inhibits non-small cell lung cancer via promotion of Prdx6- and caspase-3-mediated mitochondrial apoptosis

Glycyrrhetinic acid (GA) shows great efficiency against non-small cell lung cancer (NSCLC), but the detailed mechanism is unclear, which has limited its clinical application. Herein, we investigated the potential targets of GA against NSCLC by activity-based protein profiling (ABPP) technology and the combination of histopathology and proteomics validation. In vitro and in vivo results indicated GA significantly inhibited NSCLC via promotion of peroxiredoxin-6 (Prdx6) and caspase-3 (Casp3)-mediated mitochondrial apoptosis. This original finding will provide theoretical and data support to improve the treatment of NSCLC with the application of GA.

Enhanced IRE1α Phosphorylation/Oligomerization-Triggered XBP1 Splicing Contributes to Parkin-Mediated Prevention of SH-SY5Y Cell Death under Nitrosative Stress

Mutations in parkin, a neuroprotective protein, are the predominant cause of autosomal recessive juvenile Parkinson's disease. Neuroinflammation-derived nitrosative stress has been implicated in the etiology of the chronic neurodegeneration. However, the interactions between genetic predisposition and nitrosative stress contributing to the degeneration of dopaminergic (DA) neurons remain incompletely understood. Here, we used the SH-SY5Y neuroblastoma cells to investigate the function of parkin and its pathogenic mutants in relation to cell survival under nitric oxide (NO) exposure. The results showed that overexpression of wild-type parkin protected SH-SY5Y cells from NO-induced apoptosis in a reactive oxygen species-dependent manner. Under nitrosative stress conditions, parkin selectively upregulated the inositol-requiring enzyme 1α/X-box binding protein 1 (IRE1α/XBP1) signaling axis, an unfolded protein response signal through the sensor IRE1α, which controls the splicing of XBP1 mRNA. Inhibition of XBP1 mRNA splicing either by pharmacologically inhibiting IRE1α endoribonuclease activity or by genetically knocking down XBP1 interfered with the protective activity of parkin. Furthermore, pathogenic parkin mutants with a defective protective capacity showed a lower ability to activate the IRE1α/XBP1 signaling. Finally, we demonstrated that IRE1α activity augmented by parkin was possibly mediated through interacting with IRE1α to regulate its phosphorylation/oligomerization processes, whereas mutant parkin diminished its binding to and activation of IRE1α. Thus, these results support a direct link between the protective activity of parkin and the IRE1α/XBP1 pathway in response to nitrosative stress, and mutant parkin disrupts this function.

Tailoring carrier-free nanocombo of small-molecule prodrug for combinational cancer therapy

The outcomes of monotherapy could not satisfy clinical cancer treatment owing to the challenges of tumor heterogeneity, multi-drug resistance, tumor metastasis and relapse. In response, the significance of combinational cancer therapy has been highlighted. Traditional combinational schemes usually utilize "free" drug for multi drug administration, independently. The diverse pharmacokinetics and biodistribution greatly hinder the antitumor effects and cause systematic toxicity. To tackle the hinderance, various nanoparticulate drug delivery systems (Nano-DDSs) have been developed. However, conventional Nano-DDSs encapsulate drugs into carrier materials through noncovalent interactions, resulting in low drug loading, fixed multi drug encapsulation ratio, chemical instability and carrier-associated toxicity. Recently, carrier-free nanocombos based on self-assembling small-molecule prodrugs (SPNCs) have emerged as a versatile Nano-DDSs for multiple drug delivery. Benefited by the self-assembly capability, SPNCs could be facilely fabricated with distinct merits of ultra-high drug loading, adjustable drug ratio and negligible carrier-associated toxicity. Herein, we summarize the latest trends of SPNCs. First, a basic review on self-assembling small-molecule prodrugs is presented. Additionally, facile techniques to prepare SPNCs are introduced. Furthermore, advanced combinational therapies based on SPNCs are spotlighted with special emphasis on synergistic mechanisms. Finally, future prospects and challenges are discussed.

Novel nitric oxide donor, nitrated phenylbutyrate, induces cell death of human pancreatic cancer cells and suppresses tumor growth of cancer xenografts

Pancreatic cancer has a low response rate to chemotherapy due to the low drug transferability caused by the low blood flow around the tumor. In the present study, focusing on nitric oxide (NO) for its vasodilatory and antitumor effects, a novel NO donor, a nitrated form of phenylbutyrate (NPB) was synthesized and the antitumor effect on human pancreatic cancer cells (AsPC1 and BxPC3) and xenografts was examined. Using Annexin V, NPB was confirmed to induce cell death against AsPC1 and BxPC3 in a time‑ and concentration‑dependent manner. In NPB‑exposed cells, DAF‑FM DA (a probe to detect intracellular NO) derived fluorescence was observed. Release of nitrite and nitrate from NPB in aqueous solution was very gradual until even 72 h after dissolution. Phenylbutyrate (PB) and hydroxy PB in which the nitro group of NPB was replaced with a hydroxyl group did not have the cell death‑inducing effect as observed in NPB. These results suggest that the effect of NPB was dependent on NO release form NPB. Apoptosis inhibitor, Z‑VAD FMK, had no effect on the cell death‑inducing effect of NPB, and NPB did not show significant activation of caspase‑3/7. In addition, NPB significantly decreased cellular ATP levels, suggesting that necrosis is involved in the effect of NPB. NPB also accumulated cells specifically at the S phase of the cell cycle. A single dose of NPB (10 mg/kg) into mice with established BxPC3 xenografts significantly suppressed tumor growth for at least 7 weeks without apparent toxicity. The findings of the present study indicate that NPB has potential as a novel therapeutic agent for NO‑based therapy of pancreatic cancer.

San-Huang-Chai-Zhu Formula Ameliorates Liver Injury in Intrahepatic Cholestasis through Suppressing SIRT1/PGC-1α-Regulated Mitochondrial Oxidative Stress

Background

Chinese herbal formulae possess promising applications in treating intrahepatic cholestasis.

Objective

Our study aims to explore the protective effect of the San-Huang-Chai-Zhu formula (SHCZF) on liver injury in intrahepatic cholestasis (IC) and investigate the underlying mechanism related to mitochondrial oxidative stress.

Methods

An IC rat model was established by α-naphthyl isothiocyanate induction. Hepatic histomorphology was observed through hematoxylin and eosin staining. Levels of biochemical indexes of hepatic function and oxidative stress were determined by an enzyme-linked immunosorbent assay. Cell apoptosis in liver tissues was detected by the TUNEL assay. The mRNA expression of mtDNA, SIRT1, and PGC-1α was measured by qRT-PCR, and the protein expression of Bax, Bcl-2, caspase-3, SIRT1, and PGC-1α was determined by Western blotting.

Results

SHCZF treatment attenuated liver injury in IC. Levels of hepatic function parameters were decreased after SHCZF administration. In addition, the decreased level of malondialdehyde (MDA) and the increased levels of superoxide dismutase (SOD), glutathione (GSH), and adenosine triphosphate (ATP) in hepatic mitochondria confirmed that SHCZF could attenuate oxidative stress in IC. SHCZF treatment also reduced the apoptosis in the liver tissues of IC rats. Furthermore, SHCZF administration upregulated the expression of mtDNA, SIRT1, and PGC-1α in IC.

Conclusions

SHCZF exerts a protective effect on liver injury in IC via alleviating SIRT1/PGC-1α-regulated mitochondrial oxidative stress.

O2-(2,4-dinitrophenyl) diazeniumdiolate derivative induces G2/M arrest via PTEN-mediated inhibition of PI3K/Akt pathway in hepatocellular carcinoma cells

OBJECTIVES

The study aimed to investigate whether G2/M arrest caused by O2-(2,4-dinitrophenyl) diazeniumdiolate derivative (JS-K) was related to PTEN-mediated inhibition of PI3K/Akt pathway in hepatocellular carcinoma cells.

METHODS

The cell apoptosis was detected by DAPI staining and Annexin V-FITC/PI dual staining. The cell cycle was analysed by PI staining. The expressions of cell cycle-related proteins, PTEN and PI3K/AKT pathway were measured by Western blot. The rat model of primary hepatic carcinoma was established with diethylnitrosamine to verify the antitumour effects of JS-K.

KEY FINDINGS

The morphological features of apoptosis were obviously reversed when the cells were pre-treated with bpv(pic), followed by treatment with JS-K. JS-K mediated G2/M arrest and down-regulated expressions of cyclin B1. Meanwhile, it up-regulated the expression of p-Cdk1, p-Chk2 and p-CDC25C while down-regulated that of Cdk1 and CDC25C. Furthermore, JS-K also enhanced the expressions of p21 and p27, PTEN and p53 while decreased the expressions of p-PTEN, PI3K and p-AKT. However, bpv(pic) and Carboxy-PTIO could reverse JS-K-induced G2/M cell arrest and PTEN-mediated inhibition of the PI3K/AKT pathway. The same results were also testified in the rat model of primary hepatic carcinoma.

CONCLUSIONS

JS-K caused G2/M arrest through PTEN-mediated inhibition of the PI3K/AKT pathway involving Chk2/CDC25C/Cdk1 checkpoint.

Nitric Oxide Prodrug Delivery and Release Monitoring Based on a Galactose-Modified Multifunctional Nanoprobe

Nitric oxide (NO)-based cancer therapy has attracted much attention in recent years owing to its broad effects on cancer. Low concentrations of NO stimulate cancer cell progression, while its higher levels induce cell apoptosis, and thus, it has motivated the development of probes for in situ NO release monitoring. In this work, a galactose-modified benzothiadiazole-based fluorescent probe (GalNONP/C) was synthesized as both a NO-responsive nanoprobe and NO prodrug carrier. The probe exhibited far-red emission in the range from 550 to 800 nm, and the response showed acidity preference. The galactose on the probe enabled selective targeting of hepatocellular carcinoma (HCC) cells by binding to the asialoglycoprotein receptor (ASGPR) on the cell surface. The probe also delivered low-molecular weight NO prodrug JS-K into cells and monitored the real-time release of the generated NO. Furthermore, in vivo NO imaging with tumor targeting was demonstrated in HCC orthotopic transplantation nude mice and liver sections. Compared with the control experiment using a probe without NO prodrug loading, higher fluorescence response of NO was detected in the cell (3.0 times) and liver slices of the HCC tumor model (2.7 times). This strategy may pave the way to develop nanoprobes for in situ NO monitoring and therapy evaluation in NO-related cancer therapy.

Cytotoxicity induced by fine particulate matter (PM2.5) via mitochondria-mediated apoptosis pathway in rat alveolar macrophages

Although positive associations exist between ambient particulate matter (PM_2.5; diameter ≤ 2.5 μm) and the morbidity and mortality rates for respiratory diseases, the biological mechanisms of the reported health effects are unclear. Considering that alveolar macrophages (AM) are the main cells responsible for phagocytic clearance of xenobiotic particles that reach the airspaces of the lungs, the purpose of this study was to investigate whether PM_2.5 induced AM apoptosis, and investigate its possible mechanisms. Freshly isolated AM from Wistar rats were treated with extracted PM_2.5 at concentrations of 33, 100, or 300 μg/mL for 4 h; thereafter, the cytotoxic effects were evaluated. The results demonstrated that PM_2.5 induced cytotoxicity by decreasing cell viability and increasing lactate dehydrogenase (LDH) levels in AMs. The levels of reactive oxygen species (ROS) and intracellular calcium cations (Ca²⁺) markedly increased in higher PM_2.5 concentration groups. Additionally, the apoptotic ratio increased, and the apoptosis-related proteins BCL2-associated X (Bax), caspase-3, and caspase-9 were upregulated, whereas B cell lymphoma-2 (Bcl-2) protein levels were downregulated following PM_2.5 exposure. Cumulative findings showed that PM_2.5 induced apoptosis in AMs through a mitochondrial-mediated pathway, which indicated that PM_2.5 plays a significant role in lung injury diseases.

3,3'-Diindolylmethane induces gastric cancer cells death via STIM1 mediated store-operated calcium entry

3,3'-Diindolylmethane (DIM), a natural phytochemicals isolated from cruciferous vegetables, has been reported to inhibit human gastric cancer cells proliferation and induce cells apoptosis as well as autophagy, but its mechanisms are still unclear. Store-operated calcium entry (SOCE) is a main Ca²⁺ influx pathway in various of cancers, which is activated by the depletion of endoplasmic reticulum (ER) Ca²⁺ store. Stromal interaction molecular 1 (STIM1) is the necessary component of SOCE. In this study, we focus on to examine the regulatory mechanism of SOCE on DIM-induced death in gastric cancer. After treating the human BGC-823 and SGC-7901 gastric cancer cells with DIM, cellular proliferation was determined by MTT, apoptosis and autophagy were detected by flow cytometry or Hoechst 33342 staining. The expression levels of related proteins were evaluated by Western blotting. Free cytosolilc Ca²⁺ level was assessed by fluorescence monitoring under a laser scanning confocal microscope. The data have shown that DIM could significantly inhibit proliferation and induce apoptosis as well as autophagy in two gastric cancer cell lines. After DIM treatment, the STIM1-mediated SOCE was activated by upregulating STIM1 and decreasing ER Ca²⁺ level. Knockdown STIM1 with siRNA or pharmacological inhibition of SOCE attenuated DIM induced apoptosis and autophagy by inhibiting p-AMPK mediated ER stress pathway. Our data highlighted that the potential of SOCE as a promising target for treating cancers. Developing effective and selective activators targeting STIM1-mediated SOCE pathway will facilitate better therapeutic sensitivity of phytochemicals acting on SOCE in gastric cancer. Moreover, more research should be performed to validate the efficacy of combination chemotherapy of anti-cancer drugs targeting SOCE for clinical application.

Cascaded amplification of intracellular oxidative stress and reversion of multidrug resistance by nitric oxide prodrug based-supramolecular hydrogel for synergistic cancer chemotherapy

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Supramolecular hydrogel was facilely developed by self-assembly of NO prodrug conjugated hydrogelator sequence.

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The locoregionally sustained NO release from the hydrogel could be triggered by intracellular over-expressed GSH/GST.

•

NO could effectively reverse the P-gp mediated MDR effect and facilitate the intracellular accumulation of DOX.

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This type of stimuli-sensitive NO delivery platform holds great potential for combating drug-resistance cancer.

Purification of Gekko Small Peptide Fraction and Its Effect of Inducing Apoptosis of EC 9706 Esophageal Cancer Cells by Inhibiting PI3K/Akt/GLUT1 Signaling Pathway

This study aimed to isolate and purify a cytotoxic extraction from Gekko japonicus, identify its components and determine its cytotoxic activity in vitro. We isolated and identified the most potent cytotoxic Gekko small peptide LH-20-15. The identification and analysis of peptide sequences of LH-20-15 were performed by de novo peptide sequencing, and two new peptides were found. LH-20-15 significantly inhibited the proliferation of human esophageal squamous carcinoma EC 9706 cells in a dose-dependent manner. Furthermore, LH-20-15 induced apoptosis in esophageal cancer cells by activating the mitochondrial apoptotic pathway. Further research showed that LH-20-15 inhibited the PI3 K/Akt/GLUT1 signaling pathway. In conclusion, LH-20-15 from Gekko japonicus is a peptide mixture and may inhibit EC 9706 cell proliferation and induce apoptosis by activating the mitochondrial apoptotic pathway. It also regulates glucose metabolism by targeting the PI3 K/Akt/GLUT1 signaling pathway. These small peptides could be new sources of natural cytotoxic ingredients against esophageal cancer with potential drug values.

Exogenous NO induces apoptosis of hepatocellular carcinoma cells via positive p38/JNK signaling pathway and negative ERK signaling pathways

JS-K as an exogenous NO donor could release NO after activation by glutathione S-transferases (GSTs). The present study explores the effects of JS-K on MAPK pathway in HepG2 and Bel-7402 cells. JS-K significantly prompted apoptosis and SB203580 (a p38 inhibitor) and SP600125 (a JNK inhibitor) prior to JS-K could partly reverse apoptosis and activation of cleaved-caspase-3 and cleaved PARP. However, U0126 (a MEK inhibitor) strengthened the cell apoptosis and the expressions of cleaved-caspase-3 and cleaved PARP. JS-K caused phosphorylation of p38 MAPK and JNK but attenuated phosphorylation of ERK, which were reversed by Carboxy-PTIO (a NO scavenger). Meanwhile, the phosphorylation of HSP27, c-JUN and ATF-2 were activated in JS-K-treated cells. SB203580 and SP600125 could attenuate phosphorylation of p38 MAPK and JNK, respectively. The phosphorylation in downstream substrates of p38 MAPK and JNK was also abolished by SB203580 and SP600125 in JS-K-treated cells. Additionally, JS-K decreased phosphorylation of c-Raf, which subsequently caused a decrease of MEK1/2 phosphorylation. Several downstream targets of ERK1/2 including p90RSK and transcription factors (e.g., Elk-1, c-Myc and c-Fos) were inhibited. U0126 potentiated JS-K-induced inhibitory effect of Raf/MEK/ERK pathway. The same results were also observed in the downstream substrates of ERK1/2 including p90RSK, Elk-1, c-Myc and c-Fos. Moreover, Carboxy-PTIO abolished the inhibitory effect of Raf/MEK/ERK pathway triggered by JS-K. Finally, JS-K significantly suppressed the growth of rat primary hepatic carcinoma via MAPK pathway in vivo. Taken together, JS-K can induce hepatocellular carcinoma cells apoptosis through its activation of JNK and p38 MAPK and inactivation of Raf/MEK/ERK signaling pathways.

Nitric oxide induces HepG2 cell death via extracellular signal-regulated protein kinase activation by regulating acid sphingomyelinase

Nitric oxide (NO) plays a vital role in the occurrence and development of tumours. Acid sphingomyelinase (ASM) participates in cell apoptosis, cell proliferation, metabolism and other biological processes. However, whether ASM has an effect on NO-treated HepG2 cells remains unknown, and the role of the extracellular signal-regulated protein kinase (ERK) pathway is also unclear. In the present study, the effects of NO on cell viability and apoptosis were assayed, followed by investigating the mRNA and protein levels of ASM and ERK phosphorylation in NO-treated HepG2 cells. The results showed that diethylenetriamine/NO (DETA-NO), an NO donor, promoted HepG2 cell death and apoptosis in a concentration-dependent manner and that the mRNA and protein expression levels of ASM were significantly decreased in DETA-NO-treated HepG2 cells. Moreover, ERK phosphorylation was significantly increased in DETA-NO-treated HepG2 cells. The inhibition of ERK phosphorylation increased DETA-NO-induced cell apoptosis. In summary, DETA-NO can promote HepG2 cell death in a concentration-dependent manner by activating ERK and NO might activate ERK by regulating ASM and then inducing HepG2 cell death.

Li-Dan-He-Ji Improves Infantile Cholestasis Hepatopathy Through Inhibiting Calcium-Sensing Receptor-Mediated Hepatocyte Apoptosis

Infantile cholestatic hepatopathy (ICH) is a clinical syndrome characterized by the accumulation of cytotoxic bile acids in infancy, leading to serious liver cirrhosis or liver failure. The aetiology of ICH is complicated and some of them is unknown. Regardless of the aetiology, the finial pathology of ICH is hepatocyte apoptosis caused by severe and persistent cholestasis. It is already known that activation of calcium-sensing receptor (CaSR) could lead to the apoptosis of cardiomyocytes. However, the mechanism by CaSR-mediated cholestasis-related hepatocyte apoptosis is not fully understood. Li-Dan-He-Ji (LDHJ), a Traditional Chinese Medicine prescription, was developed to treat ICH. Another aim of this study was to investigate the possible mechanisms of LDHJ in cholestasis-related hepatocyte apoptosis. Using the primary hepatocytes, we first investigated the molecular mechanism of CaSR-mediated hepatocyte apoptosis in cholestasis. Then we prepared LDHJ granules and used ultra-high-performance liquid chromatography to identify the predominant drugs; confirmed the stability of the main substances; and for cell experiments screened forsythoside-A, emodin and chlorogenic acid as the three active substances of LDHJ granules. In the young rats with ANIT-induced intrahepatic cholestasis and the primary hepatocytes with TCDC-induced cholestasis-related hepatocyte apoptosis, the levels of liver injury and cholestasis-related biomarkers, calcium-sensing receptor (CaSR), hepatocyte apoptosis, Bax/Bcl-2 ratio, Cytochrome-C, caspase-3, phosphorylated-c-Jun NH₂-terminal kinase (p-JNK)/JNK, and p-P38/P38 were all increased, while the levels of p-extracellular signal-regulated kinase (p-ERK)/ERK were decreased. However, LDHJ granules and its three active substances effectively reversed these changes. Furthermore, the three active substances reduced the increases in the intracellular calcium concentration ([Ca²⁺]_i) and ROS levels and attenuated the dissipation of the mitochondria membrane potential in the TCDC-induced primary hepatocytes. The opposite results were obtained from the TCDC-induced primary hepatocytes treated with an agonist of CaSR (GdCl₃) plus forsythoside-A, emodin or chlorogenic acid. Based on the results from in vivo and in vitro studies, LDHJ functions as an antagonist of CaSR to regulate hepatocyte apoptosis in cholestasis through the mitochondrial pathway and mitogen-activated protein kinase pathway.

Identification of H2S/NO-donating artemisinin derivatives as potential antileukemic agents

Three H₂S/NO-donating artemisinin derivatives were designed and synthesized. Their antiproliferative activities were evaluated against human acute myeloid leukemia (AML) cell lines of K562 and K562/ADR and human normal liver cells of LO2. Biological evaluation indicated that NO-donating compound 10c exhibited the most potent cytotoxicity against leukemia cells, similar to the bioactivity of clinical drug of homoharringtonine, but showed less toxicity than homoharringtonine against LO2 cells. Further mechanism studies revealed that 10c could enhance the levels of intracellular NO and ROS, induce apoptosis and S phase cell cycle arrest, and disturb the mitochondrial membrane potential in K562 and K562/ADR cells. Western blot results demonstrated that 10c noticeably promoted autophagy by up-regulating the levels of Beclin1 and L3-II expression, inhibited the AKT signaling, and stimulated the AMPK and JNK signaling in both leukemia cell lines. Overall, 10c exhibited the potential to be a promising candidate for the therapy of AML.

Conjugate 10c exhibited potential antiproliferative activity against human acute myeloid leukemia cells.