Targeting PRSS23 with tipranavir induces gastric cancer stem cell apoptosis and inhibits growth of gastric cancer via the MKK3/p38 MAPK-IL24 pathway

Gastric cancer stem cells (GCSCs) contribute to the refractory features of gastric cancer (GC) and are responsible for metastasis, relapse, and drug resistance. The key factors drive GCSC function and affect the clinical outcome of GC patients remain poorly understood. PRSS23 is a novel serine protease that is significantly up-regulated in several types of cancers and cancer stem cells, and related to tumor progression and drug resistance. In this study, we investigated the role of PRSS23 in GCSCs as well as the mechanism by which PRSS23 regulated the GCSC functions. We demonstrated that PRSS23 was critical for sustaining GCSC survival. By screening a collection of human immunodeficiency virus (HIV) protease inhibitors (PIs), we identified tipranavir as a PRSS23-targeting drug, which effectively killed both GCSC and GC cell lines (its IC50 values were 4.7 and 6.4 μM in GCSC1 cells and GCSC2 cells, respectively). Administration of tipranavir (25 mg·kg-1·d-1, i.p., for 8 days) in GCSC-derived xenograft mice markedly inhibited the growth of subcutaneous GCSC tumors without apparent toxicity. In contrast, combined treatment with 5-FU plus cisplatin did not affect the tumor growth but causing significant weight loss. Furthermore, we revealed that tipranavir induced GCSC cell apoptosis by suppressing PRSS23 expression, releasing MKK3 from the PRSS23/MKK3 complex to activate p38 MAPK, and thereby activating the IL24-mediated Bax/Bak mitochondrial apoptotic pathway. In addition, tipranavir was found to kill other types of cancer cell lines and drug-resistant cell lines. Collectively, this study demonstrates that by targeting both GCSCs and GC cells, tipranavir is a promising anti-cancer drug, and the clinical development of tipranavir or other drugs specifically targeting the PRSS23/MKK3/p38MAPK-IL24 mitochondrial apoptotic pathway may offer an effective approach to combat gastric and other cancers.

Spleen Toxicity of Organophosphorus Flame Retardant TDCPP in Mice and the Related Mechanisms

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is an organophosphorus flame retardant that has been utilized in recent years as a primary replacement for polybrominated diphenyl ethers (PBDEs) in a wide variety of fire-sensitive applications. However, the impact of TDCPP on the immune system has not been fully determined. As the largest secondary immune organ in the body, the spleen is considered to be an important study endpoint for determining immune defects in the body. The aim of this study is to investigate the effect of TDCPP toxicity on the spleen and its possible molecular mechanisms. In this study, for 28 consecutive days, TDCPP was administered intragastrically (i.g), and we assessed the general condition of mice by evaluating their 24 h water and food intake. Pathological changes in spleen tissues were also evaluated at the end of the 28-day exposure. To measure the TDCPP-induced inflammatory response in the spleen and its consequences, the expression of the critical players in the NF-κB pathway and mitochondrial apoptosis were detected. Lastly, RNA-seq was performed to identify the crucial signaling pathways of TDCPP-induced splenic injury. The results showed that TDCPP intragastric exposure triggered an inflammatory response in the spleen, likely through activating the NF-κB/IFN-γ/TNF-α/IL-1β pathway. TDCPP also led to mitochondrial-related apoptosis in the spleen. Further RNA-seq analysis suggested that the TDCPP-mediated immunosuppressive effect is associated with the inhibition of chemokines and the expression of their receptor genes in the cytokine-cytokine receptor interaction pathway, including four genes of the CC subfamily, four genes of the CXC subfamily, and one gene of the C subfamily. Taken together, the present study identifies the sub-chronic splenic toxicity of TDCPP and provides insights on the potential mechanisms of TDCPP-induced splenic injury and immune suppression.

Selenium-Modified Chitosan Induces HepG2 Cell Apoptosis and Differential Protein Analysis

INTRODUCTION

Chitosan is the product of the natural polysaccharide chitin removing part of the acetyl group, and exhibits various physiological and bioactive functions. Selenium modification has been proved to further enhance the chitosan bioactivities, and has been a hot topic recently.

METHODS

The present study aimed to investigate the potential inhibitory mechanism of selenium-modified chitosan (SMC) on HepG2 cells through MTT assays, morphological observation, annexin V-FITC/PI double staining, mitochondrial membrane potential determination, cell-cycle detection, Western blotting, and two-dimensional gel electrophoresis (2-DE).

RESULTS

The results indicated that SMC can induce HepG2 cell apoptosis with the cell cycle arrested in the S and G2/M phases and gradual disruption of mitochondrial membrane potential, reduce the expression of Bcl2, and improve the expression of Bax, cytochrome C, cleaved caspase 9, and cleaved caspase 3. Also, 2-DE results showed that tubulin α1 B chain, myosin regulatory light chain 12A, calmodulin, UPF0568 protein chromosome 14 open reading frame 166, and the cytochrome C oxidase subunit 5B of HepG2 cells were downregulated in HepG2 cells after SMC treatment.

DISCUSSION

These data suggested that HepG2 cells induced apoptosis after SMC treatment via blocking the cell cycle in the S and G2/M phases, which might be mediated through the mitochondrial apoptotic pathway. These results could be of benefit to future practical applications of SMC in the food and drug fields.

Potential Biochemical Pesticide-Synthesis of Neofuranocoumarin and Inhibition the Proliferation of Spodoptera frugiperda Cells through Activating the Mitochondrial Pathway

Furanocoumarins, the secondary metabolites of plants, are considered to be natural insecticides and fungicides because they prevent the invasion of plant pathogenic microorganisms and the predation of herbivorous insects. In this study, novel 2-arylfuranocoumarin derivatives were designed to synthesize by condensation, esterification, bromination, and Wittig reaction. The results showed an excellent photosensitive activity of 2-thiophenylfuranocoumarin (I34). Cell Counting Kit-8 detected that I34 could inhibit the proliferation of Spodoptera frugiperda (Sf9) cells in a time- and concentration-dependent manner under ultraviolet A (UV-A) light for 3 min. The inverted microscope revealed that cells treated with I34 swelled, the membrane was ruptured, and apoptotic bodies appeared. The flow cytometry detected that I34 could induce apoptosis of Sf9 cells, increase the level of intracellular reactive oxygen species (ROS), decrease the mitochondrial membrane potential, and block cell cycle arrest in the G2/M phase. Transmission electron microscopy detected cell mitochondrial cristae damage, matrix degradation, and mitochondrial vacuolation. Further enzyme activity detection revealed that the enzyme activities of apoptosis-related proteins caspase-3 and caspase-9 increased significantly (p < 0.05). Finally, Western blotting analysis detected that the phosphorylation level of Akt and Bad and the expression of the apoptosis inhibitor protein Bcl-XL were inhibited, cleaved-PARP and P53 were increased, and cytochrome C was released from the mitochondria into the cytoplasm. Moreover, under UV-A irradiation, I34 promoted the increase in ROS in Sf9 cells, activated the mitochondrial apoptotic signal transduction pathway, and finally, inhibited cell proliferation. Thus, novel furanocoumarins exhibit a potential application prospect as a biochemical pesticide.

Chelerythrine-Induced Apoptotic Cell Death in HepG2 Cells Involves the Inhibition of Akt Pathway and the Activation of Oxidative Stress and Mitochondrial Apoptotic Pathway

Chelerythrine (CHE) is a majorly harmful isoquinoline alkaloid ingredient in Chelidonium majus that could trigger potential hepatotoxicity, but the pivotal molecular mechanisms remain largely unknown. In the present study, CHE-induced cytotoxicity and the underlying toxic mechanisms were investigated using human HepG2 cells in vitro. Data showed that CHE treatment (at 1.25–10 μM)-induced cytotoxicity in HepG2 cells is dose-dependent. CHE treatment increased the production of ROS and induced oxidative stress in HepG2 cells. Additionally, CHE treatment triggered the loss of mitochondrial membrane potential, decreased the expression of mitochondrial complexes, upregulated the expression of Bax, CytC, and cleaved-PARP1 proteins and the activities of caspase-9 and caspase-3, and downregulated the expression of Bcl-XL, and HO-1 proteins, finally resulting in cell apoptosis. N-acetylcysteine supplementation significantly inhibited CHE-induced ROS production and apoptosis. Furthermore, CHE treatment significantly downregulated the expression of phosphorylation (p)-Akt (Ser473), p-mTOR (Ser2448), and p-AMPK (Thr172) proteins in HepG2 cells. Pharmacology inhibition of Akt promoted CHE-induced the downregulation of HO-1 protein, caspase activation, and apoptosis. In conclusion, CHE-induced cytotoxicity may involve the inhibition of Akt pathway and the activation of oxidative stress-mediated mitochondrial apoptotic pathway in HepG2 cells. This study sheds new insights into understanding the toxic mechanisms and health risks of CHE.

Duck Tembusu virus infection induces mitochondrial-mediated and death receptor-mediated apoptosis in duck embryo fibroblasts

Duck Tembusu virus (DTMUV) is a pathogenic flavivirus that has caused enormous economic losses in Southeast Asia. Our previous study showed that DTMUV could induce duck embryo fibroblast (DEF) apoptosis, but the specific mechanism was not clear. In this study, we confirmed that DTMUV could induce the apoptosis of DEFs by DAPI staining and TUNEL staining. Furthermore, we found that the expression levels of cleaved-caspase-3/7/8/9 were significantly upregulated after DTMUV infection. After treatment of cells with an inhibitor of caspase-8 or caspase-9, DTMUV-induced apoptosis rates were significantly decreased, indicating that the caspase-8-mediated death receptor apoptotic pathway and caspase-9-mediated mitochondrial apoptotic pathway were involved in DTMUV-induced apoptosis. Moreover, we found that DTMUV infection not only caused the release of mitochondrial cytochrome C (Cyt C) and the downregulation of the apoptosis-inhibiting protein Bcl-2 but also reduced the mitochondrial membrane potential (MMP) and the accumulation of intracellular reactive oxygen species (ROS). Key genes in the mitochondrial apoptotic pathway and death receptor apoptotic pathway were upregulated to varying degrees, indicating the activation of the mitochondrial apoptosis pathway and death receptor apoptosis pathway. In conclusion, this study clarifies the molecular mechanism of DTMUV-induced apoptosis and provides a theoretical basis for revealing the pathogenic mechanism of DTMUV infection.

Novel Scopoletin Derivatives Kill Cancer Cells by Inducing Mitochondrial Depolarization and Apoptosis

BACKGROUND

Natural products and their molecular frameworks have been explored as invaluable sources of inspiration for drug design by means of structural modification, computer-aided drug design, and so on. Scopoletin extracting from multiple herbs exhibits potential anti-cancer activity in vitro and in vivo without toxicity towards normal cells.

OBJECTIVE

The study aims to obtain new scopoletin derivatives with enhanced anti-cancer activity. We performed chemical structure modification and researched the mechanism of anti-tumor activity.

METHODS

In this study, we considered scopoletin as a lead compound, designed and synthesized a series of scopoletin derivatives via introducing different heterocyclic fragments, and their chemical structures were characterized by NMR spectra (¹H NMR and ¹³C NMR) and HRMS(ESI). The antiproliferative activity of target compounds in four cancer cell lines (MDA-MB-231, MCF-7, HepG2, and A549) was determined by the MTT assay. Compound 11b was treated with Ac-cys under different reaction conditions to explore the thiol addition activity of it. The Annexin V/PI and JC-1 staining assay were performed to investigate the anti-tumor mechanism of 11b.

RESULTS

Novel compounds 8a-h and 11a-h derivatives of scopoletin were synthesized. Most of the target compounds exhibited enhanced antiproliferative activity against different cancer cells and reduced toxicity towards normal cells. In particular, 11b displayed the optimal antitumor ability against breast cancer MDA-MB- 231 cells with an IC₅₀ value of 4.46 μM. Compound 11b also cannot react with Ac-cys under the experimental condition. When treated with 11b for 24 h, the total apoptotic cells increased from 10.8% to 79.3%. Besides, 11b induced the depolarization of mitochondrial membrane potential.

CONCLUSION

Compound 11b was more active than other derivatives, indicating that the introduction of thiophene fragment was beneficial for the enhancement of antitumor effect, and it was also not an irreversible inhibitor based on the result that the α, β-unsaturated ketones of 11b cannot undergo Michael addition reactions with Accys. Furthermore, studies on the pharmacological mechanism showed that 11b induced mitochondrial depolarization and apoptosis, which indicated that 11b killed cancer cells via a mitochondrial apoptotic pathway. Therefore, in-depth research and structure optimization of this compound is warranted.

Induction of mitochondrial apoptosis pathway mediated through caspase-8 and c-Jun N-terminal kinase by cadmium-activated Fas in rat cortical neurons

Cadmium (Cd) is a toxic metal and an environmental pollutant and can cause neurotoxicity by inducing apoptosis. Fas (CD95/Apo-1) is a cell-surface receptor that triggers apoptosis upon ligand binding, mediated through the mitochondrial apoptotic pathway. However, the role and regulatory mechanism of Fas in Cd-induced neuronal apoptosis remain understudied. Here, we demonstrate that activation of caspase-8 and the c-Jun N-terminal kinase (JNK) pathway are mechanisms underlying Cd-induced Fas-mediated activation of the mitochondrial apoptotic pathway in rat cerebral cortical neurons. In vitro, Cd induced apoptosis in primary cortical neurons by activating caspase-8, JNK, and the mitochondrial apoptotic pathway. Fas knockdown enhanced cell viability in the presence of Cd and inhibited apoptosis by blocking Cd-activated Fas, caspase-8, and JNK. Fas knockdown also inhibited the decrease of mitochondrial membrane potential, cleavage of caspase-9/3 and poly (ADP-ribose) polymerase 1, and impaired nuclear translocation of apoptosis-inducing factor and endonuclease G. In vivo, Fas knockdown alleviated Cd-induced neuronal injury and inhibited apoptosis, activation of caspase-8, JNK, and mitochondrial apoptotic pathways in rat cerebral cortical neurons. In summary, our results demonstrate that Cd-activated Fas relays apoptotic signals from the cell surface to the mitochondria via caspase-8 and JNK activation in rat cerebral cortical neurons, leading to aggravation of the neuronal injury.

The effect of reproductive toxicity induced by ZnO NPs in mice during early pregnancy through mitochondrial apoptotic pathway

The potential toxicity of Zinc oxide nanoparticles (ZnO NPs) to human beings has become a widespread concern. This study explored the reproductive toxicity and the mechanism of toxicity of ZnO NPs in early pregnant mice. The results showed that abnormal weight changes, induced inflammation, reduced level of serum sex hormones, damaged uterus, increased abortion, and abnormal development of fetus. In the uterus, the transcription levels of ZnT-1, HO-1, Bax, Bax/Bcl-2, JNK, and Caspase-3 were significantly up-regulated while Bcl-2, ER-1 and PR were significantly down-regulated. The TUNEL-positive cells increased that were exposed to high levels of ZnO NPs. In summary, those results indicated that Zn from high levels of exposure to ZnO NPs accumulated in the uterus that could have caused the formation of ROS that led to oxidative stress, which might have activated the mitochondrial apoptotic pathway that could have caused the uterine injury which induced the observed reproductive toxicity.

Zika virus infection induced apoptosis by modulating the recruitment and activation of pro-apoptotic protein Bax

Zika virus (ZIKV) infection is associated with microcephaly in newborns and serious neurological complications in adults. Apoptosis of neural progenitor cells induced by ZIKV infection is believed to be a main reason for ZIKV infection-related microcephaly. However, the detailed mechanism of ZIKV infection-induced apoptosis remains to be elucidated. In this report, ZIKV infection induced the conformational activation of the pro-apoptotic protein Bax, with subsequent formation of oligomers of Bax in the mitochondria. Cell apoptosis was reduced significantly in SY5Y cells subjected to Bax knockdown. Additionally, while decreasing Bax expression inhibited the release of Cyt c from the mitochondria and reduced the rate of loss of mitochondrial membrane potential induced by ZIKV infection, silencing Bak, caspase-8, and/or caspase-10 expression did not. Mitochondria isolated from the untreated ZIKV-infected cells displayed Bax-binding ability and the subsequent release of Cyt c. This study also indicated that the NS4B protein of ZIKV recruited Bax to the mitochondria and induced Bax conformational activation. The overexpressed NS4B was localized to the mitochondria and induced cell apoptosis by activating the pro-apoptotic protein Bax. All the above results indicated that ZIKV infection directly impacted the mitochondrial apoptotic pathway by modulating the recruitment and activation of Bax.Importance: Since the large outbreaks that occurred in the Pacific Islands and Latin America in 2013, Zika virus has been confirmed a neuroteratogenic pathogen and causative agent of microcephaly and other developmental anomalies of the central nervous system in children born to infected mothers. As the widespread apoptosis throughout the whole brain, studies in animal models have reinforced the link between microcephaly caused by ZIKV infection and NPC apoptosis. Currently, the detailed mechanism of ZIKV infection-induced apoptosis still remains to be elucidated. Here, we firstly demonstrate that ZIKV infection activated the classic signs of mitochondrial apoptotic pathway by modulating the recruitment and activation of Bax. ZIKV NS4B represents a novel viral apoptotic protein that can modulate the recruitment and activation of Bax and trigger the apoptotic program. This is a new insight into understanding the interplay between apoptosis and ZIKV infection.

Lycorine hydrochloride induces reactive oxygen species-mediated apoptosis via the mitochondrial apoptotic pathway and the JNK signaling pathway in the oral squamous cell carcinoma HSC-3 cell line

Poor drug efficacy is a prominent cause of oral squamous cell carcinoma (OSCC) treatment failure. Although increased efforts in developing OSCC therapeutic strategies have been achieved in recent decades, the 5-year survival rate of patients with OSCC remains poor and effective drugs to treat OSCC are lacking. The aim of the present study was to investigate the apoptotic effect caused by lycorine hydrochloride (LH) and to identify its mechanism in the OSCC HSC-3 cell line. The findings demonstrated that LH effectively induced HSC-3 cell apoptosis and cell cycle arrest at the G₀/G₁ phase, resulting in the inhibition of cell proliferation. Furthermore, it was found that LH increased reactive oxygen species (ROS) production, triggered mitochondrial membrane potential (MMP) disorder, enhanced the protein expression levels of Bax, Bim, cleaved caspase-9, caspase-3 and poly(ADP-ribose) polymerase 1 and decreased Mcl-1 expression. The protein expression levels of important members of the JNK signaling pathway, including phosphorylated (p)-JNK, p-mitogen-activated protein kinase kinase 4 and p-c-Jun, were significantly increased in LH-treated cells, accompanied by an increase in ROS. However, N-acetyl cysteine (NAC), a potent antioxidant, reversed the upregulated mRNA expression of c-Jun, as well as the enhanced ROS production, the disorder of MMP and the apoptosis of HSC-3 cells induced by LH. These results suggested that LH may induce HSC-3 cell apoptosis via the ROS-mediated mitochondrial apoptotic pathway and the JNK signaling pathway, which indicated that LH may be a potential drug candidate for anti-OSCC therapy.

Synthetic Cannabinoids Induce Autophagy and Mitochondrial Apoptotic Pathways in Human Glioblastoma Cells Independently of Deficiency in TP53 or PTEN Tumor Suppressors

Simple Summary

Glioblastomas (GBMs) are aggressive brain tumors with frequent genetic defects in TP53 and PTEN tumor suppressor genes, which render tumors refractory to standard chemotherapeutics. Natural and synthetic cannabinoids showed antitumor activity in glioma cells and animal glioma models. Due to differences in the expression of cannabinoid type 2 receptors (CB2), which are abundant in GBMs but absent from a healthy brain, we tested synthetic cannabinoids for their ability to kill numerous glioma cells. We performed multiple biochemical analyses to determine which cell death pathways are activated in human glioma cells. We demonstrate high susceptibility of human glioblastoma cells to synthetic cannabinoids, despite genetic defects contributing to apoptosis resistance, which makes cannabinoids promising anti-glioma therapeutics.

Abstract

Glioblastomas (GBMs) are aggressive brain tumors with frequent genetic alterations in TP53 and PTEN tumor suppressor genes rendering resistance to standard chemotherapeutics. Cannabinoid type 1 and 2 (CB1/CB2) receptor expression in GBMs and antitumor activity of cannabinoids in glioma cells and animal models, raised promises for a targeted treatment of these tumors. The susceptibility of human glioma cells to CB2-agonists and their mechanism of action are not fully elucidated. We determined CB1 and CB2 expression in 14 low-grade and 21 high-grade tumor biopsies, GBM-derived primary cultures and established cell lines. The non-selective CB receptor agonist WIN55,212-2 (but not its inactive enantiomer) or the CB2-selective agonist JWH133 induced apoptosis in patient-derived glioma cultures and five established glioma cell lines despite p53 and/or PTEN deficiency. Growth inhibitory efficacy of cannabinoids correlated with CB1/CB2 expression (EC₅₀ WIN55,212-2: 7.36–15.70 µM, JWH133: 12.15–143.20 µM). Treatment with WIN55,212-2 or JWH133 led to activation of the apoptotic mitochondrial pathway and DNA fragmentation. Synthetic cannabinoid action was associated with the induction of autophagy and knockdown of autophagy genes augmented cannabinoid-induced apoptotic cell death. The high susceptibility of human glioblastoma cells to synthetic cannabinoids, despite genetic defects contributing to apoptosis resistance, makes cannabinoids promising anti-glioma therapeutics.

Rutin-protected BisGMA-induced cytotoxicity, genotoxicity, and apoptosis in macrophages through the reduction of the mitochondrial apoptotic pathway and induction of antioxidant enzymes

Bisphenol-A-glycidyldimethacrylate (BisGMA) is a resin monomer frequently used in dentin restorative treatments. The leakage of BisGMA monomer from BisGMA-based polymeric resins can lead to cytotoxicity in macrophages. Rutin has various beneficial bioeffects, including antioxidation and antiinflammation. In this study, we found that pretreatment of RAW264.7 macrophages with rutin-inhibited cytotoxicity induced by BisGMA in a concentration-dependent manner. BisGMA-induced apoptosis, which was detected by levels of phosphatidylserine from the internal to the external membrane and formation of sub-G1, and genotoxicity, which was detected by cytokinesis-blocked micronucleus and single-cell gel electrophoresis assays, were inhibited by rutin in a concentration-dependent manner. Rutin suppressed the BisGMA-induced activation of caspase-3 and -9 rather than caspase-8. Rutin inhibited the activation of the mitochondrial apoptotic pathway, including cytochrome C release and mitochondria disruption, after macrophages were treated with BisGMA. Finally, BisGMA-induced reactive oxygen species (ROS) generation and antioxidant enzyme (AOE) deactivation could be reversed by rutin. Parallel trends were observed in the elevation of AOE activation and inhibition of ROS generation, caspase-3 activity, mitochondrial apoptotic pathway activation, and genotoxicity. These results suggested that rutin suppressed BisGMA-induced cytotoxicity through genotoxicity, the mitochondrial apoptotic pathway, and relatively upstream factors, including reduction of ROS generation and induction of AOE.

Curcumin prevents renal cell apoptosis in acute kidney injury in a rat model of dry-heat environment heatstroke via inhibition of the mitochondrial apoptotic pathway

Heatstroke is a life-threatening illness that is characterised by a core body temperature >40^°C and central nervous system dysfunction. Acute kidney injury (AKI) is a common complication of heatstroke, and the mitochondrial apoptotic pathway has been demonstrated to be one of the leading causes of tissue damage and cell death in AKI. Curcumin is a phenol that is extracted from turmeric and demonstrates anti-apoptotic properties. To test if curcumin can protect the kidney from injury caused by heat stress, the effect of curcumin administration on renal injury and apoptosis of renal tissue was examined in a rat model of dry-heat environment. A total of 50 Sprague-Dawley rats were randomly divided into five groups (n=10): Standard temperature control, dry-heat control and curcumin treatment groups (50, 100 and 200 mg/kg groups). After exposure to a dry-heat environment for 150 min, the rats were anesthetized and euthanized. Blood, urine and renal tissue were collected to quantify the expression of specific mitochondrial apoptosis-related molecules. Curcumin pre-treatment decreased blood urea nitrogen and serum creatinine, urinary kidney injury molecule-1, and neutrophil gelatinase-associated lipocalin levels compared with the dry-heat control group. Curcumin was also revealed to downregulate c-Jun N-terminal kinases (JNK), cytochrome c, caspase-3 and caspase-9 expression upon treatment with 100 and 200 mg/kg curcumin, which may result in inhibition of the mitochondrial apoptotic pathway in renal cells. The current study revealed that Curcumin may to have potential for preventing heatstroke-induced AKI.

Glutathione S-transferase omega 1 inhibition activates JNK-mediated apoptotic response in breast cancer stem cells

Glutathione S-transferase omega 1 (GSTO1) contributes to the inactivation of a wide range of drug compounds via conjugation to glutathione during phase reactions. Chemotherapy-induced GSTO1 expression in breast cancer cells leads to chemoresistance and promotes metastasis. In search of novel GSTO1 inhibitors, we identified S2E, a thia-Michael adduct of sulfonamide chalcone with low LC₅₀ (3.75 ± 0.73 μm) that binds to the active site of GSTO1, as revealed by molecular docking (glide score: -8.1), cellular thermal shift assay and fluorescence quenching assay (K_b  ≈ 10 × 10⁵  mol·L^-1 ). Docking studies confirmed molecular interactions between GSTO1 and S2E, and identified the hydrogen bond donor Val-72 (2.14 Å) and hydrogen bond acceptor Ser-86 (2.77 Å). Best pharmacophore hypotheses could effectively map S2E and identified the 4-methyl group of the benzene sulfonamide ring as crucial to its anti-cancer activity. Lack of a thiophenyl group in another analog, 2e, reduced its efficacy as observed by cytotoxicity and pharmacophore matching. Furthermore, GSTO1 inhibition by S2E, along with tamoxifen, led to a significant increase in apoptosis and decreased migration of aggressive MDA-MB-231 cells, as well as significantly decreased migration, invasion and mammosphere formation in sorted breast cancer stem cells (CSCs, CD24^- /CD44⁺ ). GSTO1 silencing in breast CSCs also significantly increased apoptosis and decreased migration. Mechanistically, GSTO1 inhibition activated the c-Jun N-terminal kinase stress kinase, inducing a mitochondrial apoptosis signaling pathway in breast CSCs via the pro-apoptotic proteins BAX, cytochrome c and cleaved caspase 3. Our study elucidated the role of the GSTO1 inhibitor S2E as a potential therapeutic strategy for preventing chemotherapy-induced breast CSC-mediated cancer metastasis and recurrence.

[Effects of Bcl-2 family on the thyroid cell apoptosis of experimental autoimmune thyroiditis mice induced by iodine]

OBJECTIVE

To study the effect of Bcl-2 family members on experimental autoimmune thyroiditis(EAT) and explore the pathogenesis of autoimmune thyroiditis.

METHODS

Twenty-four female 4-5 week old NOD-SCID mice were randomly divided into four groups(six mice in each group): control group, high iodine group, poly(I:C) group and high iodine combined with poly(I:C) group. Control group and poly(I:C) group were fed with distilled water, while the high iodine group and high iodine combined with poly(I:C) group were supplied with 0. 05% NaI in their drinking water for 16 weeks. Poly(I:C) group and high iodine combined with poly(I:C) group received intraperitoneal injection of 100 μL poly(I:C)(1 μg/μL) at monday, wednesday and friday of the 11 th and 15 th week. Serum and thyroid were obtained at the last day of the 16 th week. The EAT model was confirmed by ELISA method and pathological HE staining, the apoptosis of thyroid cell were detected by TUNEL method and Cyt-C immunocytochemistry assay, and the mRNA levels of Bcl-2 family members in thyroid were determined by real-time qPCR method.

RESULTS

EAT model was established using NOD-SCID mice through high-iodine feeding combined with poly(I:C) intraperitoneal injection. The degree of cell apoptosis and the Cyt-C expression levels were positively correlated with inflammation in thyroid follicular epithelial cells. The mRNA levels of Noxa, PUMA and Bid of high iodine group and high iodine combined with poly(I:C) group were higher than those in control and poly(I:C) groups(P<0. 05).

CONCLUSION

Mitochondrial apoptosis pathway is involved in the thyroid cell apoptosis of EAT induced by high iodine, and the apoptosis may be regulated by the up-regulation of Noxa, PUMA and Bid, which belong to the pro-apoptotic members of Bcl-2 family.

Naloxone attenuates ischemic brain injury in rats through suppressing the NIK/IKKα/NF-κB and neuronal apoptotic pathways

Although naloxone has been documented to exert neuroprotection in animal model of cerebral ischemia, the mechanism is not well understood. In this present study we investigated whether naloxone affected the mitochondrial apoptotic pathway in ischemic brain injury of rats. SD rats were subjected to a permanent middle cerebral artery occlusion surgery, and received naloxone (0.5, 1, 2 mg/kg, i.v.) immediately after ischemia. Neurological deficits were evaluated 24 h after ischemia using the McGraw Stroke Index, and then the rats were killed, and the brains were collected for further analyses. We show that naloxone treatment dose-dependently decreased the infarction volume and morphological injury, improved motor behavioral function, and markedly curtailed brain edema. Furthermore, naloxone administration significantly inhibited the nuclear translocation of NF-κB p65 and decreased the levels of nuclear NF-κB p65 in the ischemic penumbra. Naloxone administration also dose-dependently increased the NF-κB inhibitory protein (IκBα) levels and attenuated phosphorylated NIK and IKKα levels in the ischemic penumbra. In addition, naloxone administration dose-dependently increased Bcl-2 levels, decreased Bax levels, stabilized the mitochondrial transmembrane potential, and inhibited cytochrome c release and caspase 3 and caspase 9 activation. These results indicate that the neuroprotective effects of naloxone against ischemic brain injury involve the inhibition of NF-κB activation via the suppression of the NIK/IKKα/IκBα pathway and the obstruction of the mitochondrial apoptotic pathway in neurons.

Marinobufagenin inhibits glioma growth through sodium pump α1 subunit and ERK signaling-mediated mitochondrial apoptotic pathway

Malignant glioma is one of the most challenging central nervous system diseases to treat and has high rates of recurrence and mortality. Current therapies often fail to control tumor progression or improve patient survival. Marinobufagenin (MBG) is an endogenous mammalian cardiotonic steroid involved in sodium pump inhibition. Currently, various studies have indicated the potential of MBG in cancer treatments; however, the precise mechanisms are poorly understood. The functions of MBG were examined using colony formation, migration, cell cycle, and apoptosis assays in glioma cells. A mitochondrial membrane potential assay was performed to determine the mitochondrial transmembrane potential change, and cytochrome c release from mitochondria was assayed by fluorescence microscopy. An immunofluorescence assay was performed, and the nuclear translocation of NF‐κB in glioma cells was confirmed by confocal microscopy. Western blotting and RT‐qPCR were used to detect the protein and gene expression levels, respectively. In addition, transfection experiment of ATP1A1‐siRNA was further carried out to confirm the role of sodium pump α1 subunit in the anticancer effect of MBG in human glioma. The apoptosis‐promoting and anti‐inflammatory effects of MBG were further investigated, and the sodium pump α1 subunit and the ERK signaling pathway were found to be involved in the anticancer effect of MBG. The in vivo anticancer efficacy of MBG was also tested in xenografts in nude mice. Thus, therapies targeting the ERK signaling‐mediated mitochondrial apoptotic pathways regulated by MBG might represent potential treatments for human glioma, and this study could accelerate the finding of newer therapeutic approaches for malignant glioma treatment.

Overcoming resistance to mitochondrial apoptosis by BZML-induced mitotic catastrophe is enhanced by inhibition of autophagy in A549/Taxol cells

OBJECTIVES

Our previous in vitro study showed that 5-(3, 4, 5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) is a novel colchicine binding site inhibitor with potent anti-cancer activity against apoptosis resistance in A549/Taxol cells through mitotic catastrophe (MC). However, the mechanisms underlying apoptosis resistance in A549/Taxol cells remain unknown. To clarify these mechanisms, in the present study, we investigated the molecular mechanisms of apoptosis and autophagy, which are closely associated with MC in BZML-treated A549 and A549/Taxol cells.

METHODS

Xenograft NSCLC models induced by A549 and A549/Taxol cells were used to evaluate the efficacy of BZML in vivo. The activation of the mitochondrial apoptotic pathway was assessed using JC-1 staining, Annexin V-FITC/PI double-staining, a caspase-9 fluorescence metric assay kit and western blot. The different functional forms of autophagy were distinguished by determining the impact of autophagy inhibition on drug sensitivity.

RESULTS

Our data showed that BZML also exhibited desirable anti-cancer activity against drug-resistant NSCLC in vivo. Moreover, BZML caused ROS generation and MMP loss followed by the release of cytochrome c from mitochondria to cytosol in both A549 and A549/Taxol cells. However, the ROS-mediated apoptotic pathway involving the mitochondria that is induced by BZML was only fully activated in A549 cells but not in A549/Taxol cells. Importantly, we found that autophagy acted as a non-protective type of autophagy during BZML-induced apoptosis in A549 cells, whereas it acted as a type of cytoprotective autophagy against BZML-induced MC in A549/Taxol cells.

CONCLUSIONS

Our data suggest that the anti-apoptosis property of A549/Taxol cells originates from a defect in activation of the mitochondrial apoptotic pathway, and autophagy inhibitors can potentiate BZML-induced MC to overcome resistance to mitochondrial apoptosis.

GPER-independent inhibition of adrenocortical cancer growth by G-1 involves ROS/Egr-1/BAX pathway

We previously demonstrated that treatment of the H295R adrenocortical cancer cell line with the non-steroidal, high-affinity GPER (G protein-coupled estrogen receptor 1) agonist G-1 reduced tumor growth in vitro and in vivo through a GPER independent action. Moreover, we observed that G-1 treatment induces cell-cycle arrest and apoptosis following a sustained ERK1/2 activation. However, the precise mechanisms causing these effects were not clarified. Starting from our preliminary published results, we performed a microarray study that clearly evidenced a strong and significative up-regulation of EGR-1 gene in H295R cells treated for 24h with micromolar concentration of G-1. The microarray findings were confirmed by RT-PCR and Western-blot analysis as well as by immunofluorescence that revealed a strong nuclear staining for EGR-1 after G-1 treatment. EGR-1 is a point of convergence of many intracellular signaling cascades that control tumor cell growth and proliferation as well as others that relate to cell death machinery. Here we found that the increased Egr-1 expression was a consequence of G-1-mediated ROS-dependent ERK activation that were promptly reversed by the presence of the antioxidant n-acetyl-cysteine. Finally, we observed that silencing EGR-1 gene expression reversed the main effects induced by G-1 in ACC cells, including upregulation of the negative regulator of cell cycle, p21^Waf1/Cip1 and the positive regulator of mitochondrial apoptotic pathway, BAX, as well as the cell growth inhibition. The identified ROS/MAPK/Egr-1/BAX pathway as a potential off-target effect of the G-1 could be useful in implementing the pharmacological approach for ACC therapy.

MicroRNA-10a suppresses breast cancer progression via PI3K/Akt/mTOR pathway

Previous studies have demonstrated that microRNA-10a (miR-10a) regulates various opposing biological functions in breast cancer. The aim of the present study was to investigate the exact functions of miR-10a in the pathogenesis of breast cancer. miR-10a expression was initially detected in two human breast cancer cell lines, MCF-7 and MDA-MB-231 and a normal human mammary epithelial cell line MCF-10A. The proliferation, migration and apoptosis of breast cancer cells were analyzed using MTT assays, Transwell assays and flow cytometry, respectively, following transfection of MCF-7 and MDA-MB-231 cells with an miR-10a mimic or anti-miR-10a. The expression of phosphorylated (p-)protein kinase B (Akt), p-mammalian target of rapamycin (p-mTOR), p-ribosomal protein S6 kinase β-1 (p-p70S6K), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA), Cytochrome C (Cyt C), B-cell lymphoma 2 (Bcl-2), BCL-2 associated X, apoptosis regulator (Bax), and cleaved caspase-3 were analyzed by western blotting. The migration of MCF-7 cells pretreated with an mTOR inhibitor CCI-779, was detected using a Transwell assay. Relative miR-10a expression was significantly elevated in MDA-MB-231 breast cancer cells and was at its highest levels in MCF-7 cells. Transfection with the miR-10a mimic significantly inhibited proliferation and migration, and promoted the apoptosis of breast cancer cells. Furthermore, upregulation of miR-10a markedly suppressed the levels of p-Akt, p-mTOR, p-p70S6K, and PIK3CA, and increased the expression of Cyt C, cleaved caspase-3, and the ratio of Bax/Bcl-2. Anti-miR-10a had the opposite effects. In addition, CCI-779 reversed the effect of anti-miR-10a on the migration of MCF-7 cells in a dose-dependent manner. In conclusion, miR-10a is downregulated in high aggressive breast cancer cells. miR-10a inhibited the proliferation and migration, and promoted apoptosis of breast cancer cells via phosphoinositide/Akt/mTOR signaling, and the mitochondrial apoptotic pathway.

Anti-cancer effects of dopamine in human glioma: involvement of mitochondrial apoptotic and anti-inflammatory pathways

Despite the emergence of innovative cancer treatment strategies, the global burden imposed by malignant glioma is expected to increase; thus, new approaches for treating the disease are urgently required. Dopamine, a monoamine catecholamine neurotransmitter, is currently regarded as an important endogenous regulator of tumor growth. Dopamine may play an important role in glioma treatment; however, the mechanism underlying the anti-tumor activity of dopamine remains poorly understood. Here, we explored the potential roles of dopamine in glioma and highlight the importance of endogenous regulators of tumor growth. We report that dopamine inhibited glioma cell proliferation. We investigated the biological functions of dopamine via migration, colony formation and apoptosis assays in glioma cells. We also evaluated cytochrome c release from the mitochondria and p50 and p65 subcellular localization by fluorescence microscopy. We performed western blotting and real-time quantitative polymerase chain reaction to detect apoptosis and inflammatory marker protein and gene expression levels, respectively. NF-κB p50/p65 nuclear localization was analyzed after U87MG and U251 cells were treated with dopamine. The in vivo anti-tumor efficacy of dopamine was also analyzed in xenograft mice. Taken together, our results indicated that dopamine induced apoptosis by activating the cytochrome c and caspase-dependent apoptotic pathway. Moreover, dopamine markedly down-regulated inflammation-related protein expression levels and p50/p65 NF-κB nuclear localization in tumor cells, thereby inhibiting increases in tumor weight and size in xenograft mice. Thus, therapies targeting the mitochondrial apoptotic and anti-inflammatory signaling pathways regulated by dopamine may represent promising treatments for human glioma.

RhoBTB2 (DBC2) functions as a multifunctional tumor suppressor in thyroid cancer cells via mitochondrial apoptotic pathway

Thyroid cancer is the most common endocrine malignancy worldwide. Tumor suppressor gene RhoBTB2 (also known as Deleted in Breast Cancer 2, DBC2) was observed in various carcinomas, however, no reports showed the effects of RhoBTB2 on thyroid cancer. In our study, we found that RhoBTB2 decreases proliferation, increases apoptosis, inhibits mobility, and induces mitochondria damage in SW579 cells through increased Bax and decreased Bcl-2 and Bcl-xL protein expression. The effects of RhoBTB2 on SW579 cells were inversed by using butin (an inhibitor of the mitochondrial apoptosis pathway). Our results suggest that RhoBTB2 suppresses the growth of SW579 cells through a mitochondrial apoptosis pathway.

Glycoborinine induces apoptosis through mitochondrial pathway in HepG2 cells

Glycoborinine (GB), a natural carbazole alkaloid isolated from Glycosmis pentaphylla, has been shown to be a potential molecule against cancer cells. In this study, the cell-signaling pathway of its anti-tumor activity was investigated. MTT assay result showed that GB inhibited HepG2 cell proliferation in a dose- and time-dependent manner and 50% inhibiting concentration (IC50) of GB-induced cell death was 39.7 μM for a period of 48 h. GB-induced HepG2 apoptosis was confirmed by Hochest 33258 staining and PI staining. The level of reactive oxygen species (ROS) was measured with H2DCF-DA staining and the change of mitochondrial membrane potential (△Ψ(m)) was analyzed with tetrechloro-tetraethylbenzimidazolcarbocyanine iodide (JC-1) probe. Results showed that GB at 12.5, 25, and 50 μM promoted ROS production. GB induced HepG2 apoptosis through a mitochondrial apoptotic pathway, which was demonstrated by GB-induced increase in the ratio of Bax/Bcl-2, cytochrome C release, the ratio of cleaved caspase-3/procaspase-3, and the ratio of cleaved poly ADP-ribose polymerase (cleaved PARP)/poly ADP-ribose polymerase (PARP). To summarize, this study demonstrated that GB could induce HepG2 apoptosis through the mitochondrial-dependent pathway, which might provide a promising approach to cure liver cancer with GB.

Canstatin induces apoptosis in gastric cancer xenograft growth in mice through the mitochondrial apoptotic pathway

Canstatin, the non-collagenous domain of collagen type IV α-chains, belongs to a series of collagen-derived angiogenic inhibitors. In this study, the inhibitory effect of recombinant canstatin on tumour growth was investigated using a gastric cancer xenograft model. The volume and weight of tumours in mice treated with canstatin were lower than that in mice treated with PBS. Accordingly, the survival rate of these mice was significantly higher than that of mice bearing tumours treated with PBS. Moreover, valuable insight into the mechanisms mediated by canstatin was obtained.

Hydroxycamptothecin induces apoptosis of human tenon's capsule fibroblasts by activating the PERK signaling pathway

PURPOSE

Hydroxycamptothecin (HCPT) has been proven to induce apoptosis in fibroblasts. In this study, we investigated whether the PRKR-like ER kinase (PERK) pathway is implicated in apoptotic signaling of human Tenon's capsule fibroblasts (HTCFs) by HCPT.

METHODS

Normal and PERK-knockdown HTCFs were used in this study. Apoptosis was determined by the cell viability assay, Annexin V/propidium iodide (PI) dual-staining, cell cycle analysis in HTCFs treated with HCPT in various doses and for various durations. Endoplasmic reticulum (ER) stress markers and sensor proteins were detected by Western blot analysis. Mitochondrial dysfunction was measured by detecting the mitochondrial membrane potential (ΔΨm) and measuring the expression of cytochrome c (cyt c).

RESULTS

HCPT induced apoptosis in the HTCFs, which was characterized as decreased cell viability and sub-S fraction of the cell cycle and increased apoptosis rate by Annexin V/PI dual-staining. The activity levels of caspase-3 and caspase-9 were significantly increased and were accompanied by cytosolic release of cyt c and decreased ΔΨm in response to HCPT. Treatment with HCPT increased the expression of glucose-regulated protein 78 (GRP78), phospho-PERK, activating transcription factor 6 (ATF6), phosphoinositol-requiring kinase 1 (IRE1), C/EBP homologous protein (CHOP), Bax, and phospho-c-Jun N-terminal kinase (JNK) and decreased the expression of Bcl-2. Knockdown of PERK attenuates HCPT-induced apoptosis in HTCFs, dependent upon both ER stress and the mitochondrial apoptotic pathway.

CONCLUSIONS

This study suggests that the ER stress response and mitochondrial dysfunction are involved in apoptosis induced by HCPT in HTCFs, which might be mediated by PERK; thus, this study offers new insight into preventing postoperative scarring via treatment with HCPT.