Apoptosis induction associated with the ER stress response through up-regulation of JNK in HeLa cells by gambogic acid

Multi-spectroscopic and in silico investigation of gambogic acid-calf thymus DNA interactions

Gambogic acid (GA), a xanthanoid compound, is derived from Garcinia Hanbury gamboge resin. Studying GA's DNA binding and targeting processes is crucial to understanding its tumor-targeting potentiality. This study used spectroscopic and in silico methods to investigate the GA-calf thymus DNA-binding interaction. The results of the UV-visible absorbance spectroscopy revealed that GA binds to DNA and forms a complex. Investigation of fluorescence quenching using ethidium bromide-DNA revealed that GA displaced ethidium bromide, and the type of quenching was static in nature, as determined by Stern-Volmer plot data. Thermodynamic analysis of the DNA-GA complex revealed a spontaneous, favorable interaction involving hydrogen bonding and hydrophobic interactions. Quenching experiments with potassium iodide, Acridine orange, and NaCl verified GA's groove-binding nature and the presence of weak electrostatic interactions. The thermal melting temperature of DNA in its native and bound states with GA did not differ significantly (69.27° C to 71.25° C), validating the binding of GA to the groove region. Furthermore, the groove-binding nature of GA was confirmed by studying its interaction with ssDNA and DNA viscosity. The methods of DSC, FT-IR, and CD spectroscopy have not revealed any structural aberrations in DNA bound with GA. Molecular docking and modeling studies revealed that GA has a groove-binding nature with DNA, which is consistent with prior experimental results. Finally, the findings shed information by which GA attaches to DNA and provide insights into its recognized anticancer effects via topoisomerase inhibition causing DNA cleavage, inhibition of cell proliferation and apoptosis.Communicated by Ramaswamy H. Sarma.

Research progress on the GRP78 gene in the diagnosis, treatment and immunity of cervical cancer

BACKGROUND

GRP78 is a molecular chaperone protein in the endoplasmic reticulum that is involved in protein assembly and quality control, and it participates in ER stress regulation of endoplasmic reticulum stress pathways. Studies have confirmed that GRP78 gene is highly expressed in a variety of tumors and is involved in different biological functions.

PURPOSE

The present review highlights the involvement of the GRP78 gene in regulating the development of cervical cancer by promoting the proliferation and invasion of cervical cancer cells as well as by inhibiting apoptosis and promoting the Warburg effect. High expression of GRP78 is positively correlated with chemotherapy resistance in cervical cancer. GRP78 plays an anticancer role in cervical cancer by regulating autophagy and apoptosis. Mediated immune CD8 + T cells regulate tumor cell immunity and play a role in the application of the HPV vaccine.

CONCLUSIONS

GRP78 plays a multifunctional role in cervical cancer and has important therapeutic and diagnostic value.

Dual RNase activity of IRE1 as a target for anticancer therapies

The unfolded protein response (UPR) is a cellular mechanism that protects cells during stress conditions in which there is an accumulation of misfolded proteins in the endoplasmic reticulum (ER). UPR activates three signaling pathways that function to alleviate stress conditions and promote cellular homeostasis and cell survival. During unmitigated stress conditions, however, UPR activation signaling changes to promote cell death through apoptosis. Interestingly, cancer cells take advantage of this pathway to facilitate survival and avoid apoptosis even during prolonged cell stress conditions. Here, we discuss different signaling pathways associated with UPR and focus specifically on one of the ER signaling pathways activated during UPR, inositol-requiring enzyme 1α (IRE1). The rationale is that the IRE1 pathway is associated with cell fate decisions and recognized as a promising target for cancer therapeutics. Here we discuss IRE1 inhibitors and how they might prove to be an effective cancer therapeutic.

Erianin: A phytoestrogen with therapeutic potential

Erianin, a phytoestrogen with therapeutic potential, is one of the major active components of Dendrobll caulis. Erianin has a variety of pharmacological effects, such as anti-tumor, anti-inflammatory, anti-diabetic retinopathy, anti-psoriasis, and antibacterial effects. Especially, in regard to the anti-tumor effect of erianin, the underlying molecular mechanism has been partly clarified. In fact, the numerous pharmacological actions of erianin are complex and interrelated, mainly including ERK1/2, PI3K/Akt, JAK2/STAT3, HIF-1α/PD-L1, PPT1/mTOR, JNK/c-Jun, and p38 MAPK signal pathway. However, on account of the poor water solubility and the low bioavailability of erianin, greatly affected and limited its further development and application. And it is worthwhile and meaningful to explore more extensive pharmacological effects and mechanisms, clarify pharmacokinetics, and synthesize the derivatives of erianin. Conclusively, in this paper, the pharmacological effects of erianin and its mechanism, pharmacokinetics, and derivatives studies were reviewed, in order to provide a reference for the development and application of erianin.

Systemic deuteration of SCID mice using the water-isotopologue deuterium oxide (D2 O) inhibits tumor growth in an orthotopic bioluminescent model of human pancreatic ductal adenocarcinoma

Since its initial discovery as a natural isotopologue of dihydrogen oxide (1 H2 O), extensive research has focused on the biophysical, biochemical, and pharmacological effects of deuterated water (2 H2 O [D2 O, also referred to as "heavy water"]). Using a panel of cultured human pancreatic ductal adenocarcinoma (PDAC) cells we have profiled (i) D2 O-induced phenotypic antiproliferative and apoptogenic effects, (ii) redox- and proteotoxicity-directed stress response gene expression, and (iii) phosphoprotein-signaling related to endoplasmic reticulum (ER) and MAP-kinase stress response pathways. Differential array analysis revealed early modulation of stress response gene expression in both BxPC-3 and PANC-1 PDAC cells elicited by D2 O (90%; ≤6 h; upregulated: HMOX1, NOS2, CYP2E1, CRYAB, DDIT3, NFKBIA, PTGS1, SOD2, PTGS2; downregulated: RUNX1, MYC, HSPA8, HSPA1A) confirmed by independent RT-qPCR analysis. Immunoblot-analysis revealed rapid (≤6 h) onset of D2 O-induced MAP-kinase signaling (p-JNK, p-p38) together with ER stress response upregulation (p-eIF2α, ATF4, XBP1s, DDIT3/CHOP). Next, we tested the chemotherapeutic efficacy of D2 O-based drinking water supplementation in an orthotopic PDAC model employing firefly luciferase-expressing BxPC-3-FLuc cells in SCID mice. First, feasibility and time course of systemic deuteration (30% D2 O in drinking water; 21 days) were established using time-resolved whole-body proton magnetic resonance imaging and isotope-ratio mass spectrometry-based plasma (D/H)-analysis. D2 O-supplementation suppressed tumor growth by almost 80% with downregulated expression of PCNA, MYC, RUNX1, and HSP70 while increasing tumor levels of DDIT3/CHOP, HO-1, and p-eIF2α. Taken together, these data demonstrate for the first time that pharmacological induction of systemic deuteration significantly reduces orthotopic tumor burden in a murine PDAC xenograft model.

Heat Shock Proteins: Central Players in Oncological and Immuno-Oncological Tracks

Heat shock proteins (HSPs) are a group of proteins that promote protein folding, inhibit denaturation of cellular proteins, and maintain other proteins' functional activities when cells are subjected to stress and/or high temperature. HSP classification is generally based on their molecular weights into large and small HSP. The family of small HSPs includes HSPs 27, 40, 60, 70, and 90. The potential roles of HSP27 and HSP70 are quite evident in different solid malignancies, including breast, colorectal, pancreatic, and liver cancers. In this chapter, the authors focus on HSP27 and HSP70 signaling in oncology and their role in different solid malignancies as well as they shed light on the novel role of HSP70 and HSP90 in the immune-oncology field.

Andrographolide promote the growth and immunity of Litopenaeus vannamei, and protects shrimps against Vibrio alginolyticus by regulating inflammation and apoptosis via a ROS-JNK dependent pathway

Vibrio alginolyticus (V. alginolyticus) is one of the major pathogens causing mass mortality of shrimps worldwide, affecting energy metabolism, immune response and development of shrimps. In the context of the prohibition of antibiotics, it is necessary to develop a drug that can protect shrimp from V. alginolyticus. Andrographolide (hereinafter called Andr), a traditional drug used in Chinese medicine, which possesses diverse biological effects including anti-bacteria, antioxidant, immune regulation. In this study, we investigated the effect of Andr on growth, immunity, and resistance to V. alginolyticus infection of Litopenaeus vannamei (L. vannamei) and elucidate the underlying molecular mechanisms. Four diets were formulated by adding Andr at the dosage of 0 g/kg (Control), 0.5 g/kg, 1 g/kg, and 2 g/kg in the basal diet, respectively. Each diet was randomly fed to one group with three replicates of shrimps in a 4-week feeding trial. The results showed that dietary Andr improved the growth performance and non-specific immune function of shrimps. L. vannamei fed with Andr diets showed lower mortality after being challenged by V. alginolyticus. After 6 h of V. alginolyticus infection, reactive oxygen species (ROS) production, tissue injury, apoptosis, expression of inflammatory factors (IL-1 β and TNFα) and apoptosis-related genes (Bax, caspase3 and p53) were increased in hemocytes and hepatopancreas, while feeding diet with 0.5 g/kg Andr could inhibit the increase. Considering that JNK are important mediators of apoptosis, we examined the influence of Andr on JNK activity during V. alginolyticus infection. We found that Andr inhibited JNK activation induced by V. alginolyticus infection on L. vannamei. The ROS scavenger N-acetyl-l-cysteine (NAC) suppressed V. alginolyticus-induced inflammation and apoptosis, suggesting that ROS play an important role in V. alginolyticus-induced inflammation and apoptosis. Treated cells with JNK specific activator anisomycin, the inflammation and apoptosis inhibited by Andr were counteracted. Collectively, Andr promote the growth and immunity of L. vannamei, and protects shrimps against V. alginolyticus by regulating inflammation and apoptosis via a ROS-JNK dependent pathway. These results improve the understanding of the pathogenesis of V. alginolyticus infection and provide clues to the development of effective drugs against V. alginolyticus.

6-Methoxylated Flavonoids: Jacein, and 3-demethyljacein from Centaurea schmidii with Their Endoplasmic Reticulum Stress and Apoptotic Cell Death in Breast Cancer Cells Along with In-silico Analysis

In phytochemical analysis, Jacein derivatives: 5,7,4'-trihydroxy-3,6,3'-trimethoxyflavone-7(β)-D-glucopyranoside (1), and 3-demethyljacein: 3,5,7,4'-tetrahydroxy-6,3'-dimethoxyflavone-7(β)-D-glucopyranoside (2) were isolated from Campylopus schmidii (C. schmidii) for the first time. The structures were determined by interpretation of NMR, UV, and Mass spectra. To check the roles of ER stress and consequent apoptosis in MCF-7 cell by these compounds, UPR signaling pathway was further examined by analysis of expression of ER stress-related genes. In MTT assay, compounds 1-2 showed cytotoxicity activity against MCF-7 (A) and MDA-MB cells (B) with IC₅₀ values (μM) of 1) 60.04 ± 7.98 (A), and > 200 (B); 2) 42.89 ± 1.91 (A), and 85.31 ± 2.68 (B). The Annexin/PI flow cytometry apoptosis of tested compounds 1-2 was increased significantly in a dose-dependent manner. For example, MCF-7 treatment at the concentration of 100 μM of compounds 1, 2 resulted in total apoptosis (early + late) of 42.04 (18.1 + 24.0), and 66.49 (2.7 + 63.8)%, respectively. Fluorescence microscopy analysis detected an increased protein aggregation, indicating induced ER stress with a marked increase in XBP-1, sXBP-1, ATF-4, and CHoP compared to untreated cells. In-silico characterization, suggested that Adenosine diphosphate site (A-site) and quercetin site (Q-Site) in IRE1a enzyme are both available interacting sites of a target for the investigated ligands but with different strengths of interactions. The results indicated that the ligand∼A-Site complexes are stronger than the ligand∼Q-Site complexes, but the already available ADP ligand in cells does not allow other ligands to interact with the A-Site and cause them to bond in Q-Site.

Gambogic acid: A shining natural compound to nanomedicine for cancer therapeutics

The United States Food and Drug Administration has permitted number of therapeutic agents for cancer treatment. Most of them are expensive and have some degree of systemic toxicity which makes overbearing in clinical settings. Although advanced research continuously applied in cancer therapeutics, but drug resistance, metastasis, and recurrence remain unanswerable. These accounts to an urgent clinical need to discover natural compounds with precisely safe and highly efficient for the cancer prevention and cancer therapy. Gambogic acid (GA) is the principle bioactive and caged xanthone component, a brownish gamboge resin secreted from the of Garcinia hanburyi tree. This molecule showed a spectrum of biological and clinical benefits against various cancers. In this review, we document distinct biological characteristics of GA as a novel anti-cancer agent. This review also delineates specific molecular mechanism(s) of GA that are involved in anti-cancer, anti-metastasis, anti-angiogenesis, and chemo-/radiation sensitizer activities. Furthermore, recent evidence, development, and implementation of various nanoformulations of gambogic acid (nanomedicine) have been described.

Andrographolide induces apoptosis in human osteosarcoma cells via the ROS/JNK pathway

Osteosarcoma is the most common primary malignant tumor of the bone and the long-term survival of patients with this disease has remained unsatisfactory over the past several decades. Andrographolide, a traditional drug used in Chinese medicine, has been found to exert a significant antitumor effect against several types of cancer. However, relatively little is known about the effect of andrographolide on osteosarcoma and the underlying mechanisms. In the present study, it was shown that andrographolide inhibited osteosarcoma cell proliferation by arresting the cell cycle at the G2/M phase and increasing caspase-mediated apoptosis. Furthermore, treatment with andrographolide induced JNK activation and increased production of reactive oxygen species (ROS). The andrographolide-triggered apoptosis in osteosarcoma cells was partly abrogated by a JNK inhibitor and completely reversed by a ROS scavenger. Additionally, JNK activation and cell cycle arrest at the G2/M phase were prevented by administration of an ROS scavenger. In vivo, it was also found that andrographolide inhibited tumor growth by increasing the levels of ROS and activating JNK; thus inducing cytotoxicity in primary osteosarcoma cells. Together, the results of the present study suggest that andrographolide caused G2/M arrest and induced cell apoptosis via regulation of the ROS/JNK signaling pathway in osteosarcoma cells. Thus, andrographolide may serve as a promising antitumor therapeutic agent against osteosarcoma.

Autophagy protects PC12 cells against deoxynivalenol toxicity via the Class III PI3K/beclin 1/Bcl-2 pathway

Deoxynivalenol (DON) is a major mycotoxin from the trichothecene family of mycotoxins produced by Fusarium fungi. It can cause a variety of adverse effects on human and farm animal health. Here, we determined the effect of DON on the Class III phosphatidylinositol 3-kinase (PIK3C3)/beclin 1/B cell lymphoma-2 (Bcl-2) pathway in PC12 cells and the relationship between autophagy and apoptosis. The effects of DON were evaluated based on the apoptosis ratio; the typical indicators of autophagy, including cellular morphology, acridine orange- and monodansylcadaverine-labeled vacuoles, green fluorescent protein-microtubule associated protein 1 light chain 3 (LC3) localization, and LC3 immunofluorescence; and the expression of key autophagy-related genes and proteins, that is, PIK3C3, beclin 1, Bcl-2, LC3, and p62. The relationship between autophagy and apoptosis was analyzed by western blot analysis and flow cytometry. DON-induced PC12 cell morphological changes and autophagy significantly. PIK3C3, beclin 1, and LC3 increased in tandem with the DON concentration used; Bcl-2 and p62 expression decreased as DON concentrations increased. Moreover, the PIK3C3/beclin 1/Bcl-2 signaling pathway played a role in DON-induced autophagy. Our findings suggest that DON can induce autophagy by activating the PIK3C3/beclin 1/Bcl-2 signaling pathway and that autophagy may play a positive role in reducing DON-induced apoptosis.

Cell death mechanisms in eukaryotes

Like the organism they constitute, the cells also die in different ways. The death can be predetermined, programmed, and cleanly executed, as in the case of apoptosis, or it can be traumatic, inflammatory, and sudden as many types of necrosis exemplify. Nevertheless, there are a number of cell deaths-some of them bearing a resemblance to apoptosis and/or necrosis, and many, distinct from each-that serve a multitude of roles in either supporting or disrupting the homoeostasis. Apoptosis is coordinated by death ligands, caspases, b-cell lymphoma-2 (Bcl-2) family proteins, and their downstream effectors. Events that can lead to apoptosis include mitotic catastrophe and anoikis. Necrosis, although it has been considered an abrupt and uncoordinated cell death, has many molecular events associated with it. There are cell death mechanisms that share some standard features with necrosis. These include methuosis, necroptosis, NETosis, pyronecrosis, and pyroptosis. Autophagy, generally a catabolic pathway that operates to ensure cell survival, can also kill the cell through mechanisms such as autosis. Other cell-death mechanisms include entosis, ferroptosis, lysosome-dependent cell death, and parthanatos.

Insight Into the Role of Autophagy in Osteosarcoma and Its Therapeutic Implication

Osteosarcoma is an aggressive bone cancer that frequently metastasizes to the lungs. The cytotoxicity of most chemotherapeutics and targeted drugs in the treatment of osteosarcoma is partially lessened. Furthermore, there is a poor response to current chemo- and radiotherapy for both primary lesions and pulmonary metastases of osteosarcoma. There is a clear need to explore promising drug candidates that could improve the efficacy of osteosarcoma treatment. Autophagy, a dynamic and highly conserved catabolic process, has dual roles in promoting cell survival as well as cell death. The role of autophagy has been investigated extensively in different tumor types, and a growing body of research has highlighted the potential value of using autophagy in clinical therapy. Here, we address significant aspects of autophagy in osteosarcoma, including its functions, modulation, and possible therapeutic applications.

Salvianolic acid B protects against ANIT-induced cholestatic liver injury through regulating bile acid transporters and enzymes, and NF-κB/IκB and MAPK pathways

The purpose of this study was to investigate the pharmacological effects of salvianolic acid B (SA-B) on α-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury with the focus on bile acid homeostasis and anti-inflammatory pathways. Rats were randomly assigned into four groups. The control group was given normal saline (i.p.) for 7 consecutive days and on the 5th day was given the vehicle (i.g.). Model group was treated with normal saline (i.p.) for 7 days and administrated with ANIT (75 mg/kg, i.g.) on the 5th day. The SA-B groups were treated with SA-B (15 mg/kg and 30 mg/kg, i.p.) for 7 consecutive days as well as ANIT (75 mg/kg, i.g.) on the 5th day. We found that the serum levels of ALT, γ-GT, TBA, and other liver function indexes were found to be lower in the SA-B treatment groups than in the model group. SA-B also upregulated the transporters and enzymes involved in bile acid homeostasis such as Bsep, Oatp2, and Cyp3a2 in rats and BSEP, CYP3A4, and OATP2 in human cell lines. Moreover, SA-B suppressed NF-κB translocation into the nucleus, inhibited phosphorylation of p38 and JNK, and inhibited inflammation markers including IL-1β, IL-6, TGF-β, TNF-α, and COX-2 to extenuate cholestatic liver injury both in vivo and vitro. Taken together, our findings suggest that anti-cholestatic effects of SA-B may be associated with its ability to regulate NF-κB/IκB and MAPK inflammatory signaling pathways to inhibit inflammation and regulate transporters and enzymes to maintain bile acid homeostasis.

Role of Endoplasmic Reticulum Stress in the Anticancer Activity of Natural Compounds

Cancer represents a serious global health problem, and its incidence and mortality are rapidly growing worldwide. One of the main causes of the failure of an anticancer treatment is the development of drug resistance by cancer cells. Therefore, it is necessary to develop new drugs characterized by better pharmacological and toxicological profiles. Natural compounds can represent an optimal collection of bioactive molecules. Many natural compounds have been proven to possess anticancer effects in different types of tumors, but often the molecular mechanisms associated with their cytotoxicity are not completely understood. The endoplasmic reticulum (ER) is an organelle involved in multiple cellular processes. Alteration of ER homeostasis and its appropriate functioning originates a cascade of signaling events known as ER stress response or unfolded protein response (UPR). The UPR pathways involve three different sensors (protein kinase RNA(PKR)-like ER kinase (PERK), inositol requiring enzyme1α (IRE1) and activating transcription factor 6 (ATF6)) residing on the ER membranes. Although the main purpose of UPR is to restore this organelle's homeostasis, a persistent UPR can trigger cell death pathways such as apoptosis. There is a growing body of evidence showing that ER stress may play a role in the cytotoxicity of many natural compounds. In this review we present an overview of different plant-derived natural compounds, such as curcumin, resveratrol, green tea polyphenols, tocotrienols, and garcinia derivates, that exert their anticancer activity via ER stress modulation in different human cancers.

Tocotrienols Modulate a Life or Death Decision in Cancers

Malignancy often arises from sophisticated defects in the intricate molecular mechanisms of cells, rendering a complicated molecular ground to effectively target cancers. Resistance toward cell death and enhancement of cell survival are the common adaptations in cancer due to its infinite proliferative capacity. Existing cancer treatment strategies that target a single molecular pathway or cancer hallmark fail to fully resolve the problem. Hence, multitargeted anticancer agents that can concurrently target cell death and survival pathways are seen as a promising alternative to treat cancer. Tocotrienols, a minor constituent of the vitamin E family that have previously been reported to induce various cell death mechanisms and target several key survival pathways, could be an effective anticancer agent. This review puts forward the potential application of tocotrienols as an anticancer treatment from a perspective of influencing the life or death decision of cancer cells. The cell death mechanisms elicited by tocotrienols, particularly apoptosis and autophagy, are highlighted. The influences of several cell survival signaling pathways in shaping cancer cell death, particularly NF-κB, PI3K/Akt, MAPK, and Wnt, are also reviewed. This review may stimulate further mechanistic researches and foster clinical applications of tocotrienols via rational drug designs.

Hepatotoxicity induced by psoralen and isopsoralen from Fructus Psoraleae: Wistar rats are more vulnerable than ICR mice

Fructus Psoraleae (FP) causes cholestatic liver injury; however, its main toxic constituents that are responsible for causing hepatotoxicity remained undetermined in previous studies. In the present study, psoralen and isopsoralen, the two main constituents of FP, were administered orally to rats (80 and 40 mg/kg, respectively) and mice (320 and 160 mg/kg, respectively) for 28 days, followed by biochemical and histopathological examinations to evaluate their hepatotoxicity. The results showed that psoralen and isopsoralen could induce the toxic reactions of liver and other organs in rats, while mice were not sensitive to these two compounds. Furthermore, the corresponding results indicated that administration of psoralen and isopsoralen repressed the expression of CYP7A1, BSEP, MRP2 and SULT2A1 and increased the expression of FXR and MRP3 in the rat liver. In summary, the toxic reactions of psoralen and isopsoralen are different in different species. In this study, multiple organ toxicity, such as cholestatic liver injury, occurs in rats, but not in mice. Psoralen and isopsoralen are the two main toxic constituents of FP. In addition, psoralen and isopsoralen cause liver injury, possibly through inhibiting bile acid excretion in the liver, leading to the accumulation of toxin in hepatocytes.

Physcion induces apoptosis through triggering endoplasmic reticulum stress in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and aggressive malignancies. The current study aimed to investigate the effect of physcion, a major active ingredient in several traditional herbal medicinal plants, for the treatment of HCC. Our data showed that physcion markedly induced apoptosis in human HCC cell lines Huh7 and Bel7402. The pro-apoptotic role of physcion on HCC cells was mediated by mitochondria dysfunction, which was caused by activation of endoplasmic reticulum(ER) stress. Moreover, our findings revealed that physcion stimulated ER stress by activating AMPK signaling. Besides in HCC cell lines, the anti-cancer activity of physcion was also examined in a xenograft mice model, which showed that physcion could significantly suppressed tumor growth. In conclusion, our results indicated that physcion can be considered as a potential chemotherapeutic agent in the treatment of HCC.

Cholesterol Depletion by TASIN-1 Induces Apoptotic Cell Death through the ER Stress/ROS/JNK Signaling in Colon Cancer Cells

Truncated APC selective inhibitor-1 (TASIN-1) is a recently identified small molecule that selectively kills colorectal cancer cells that express truncated adenomatous polyposis coli (APC) by reducing cellular cholesterol levels. However, the downstream mechanism responsible for its cytotoxicity is not well understood. In this study, we show that TASIN-1 leads to apoptotic cell death via inducing ER stress-dependent JNK activation in human truncated APC colon cancer cells, accompanied by production of reactive oxygen species (ROS). In addition, TASIN-1 inhibits AKT activity through a cholesterol-dependent manner. Human colon tumor xenografts in immunodeficient mice also show the same TASIN-1 induced molecular mechanisms of tumor cell death as observed in vitro Taken together, cholesterol depletion by TASIN-1 treatment induces apoptotic cell death through activating ER stress/ROS/JNK axis and inhibiting AKT pro-survival signaling in colon cancer cells with truncated APC both in vitro and in vivoMol Cancer Ther; 17(5); 943-51. ©2018 AACR.

Therapeutic potential of gambogic acid, a caged xanthone, to target cancer

Natural compounds have enormous biological and clinical activity against dreadful diseases such as cancer, as well as cardiovascular and neurodegenerative disorders. In spite of the widespread research carried out in the field of cancer therapeutics, cancer is one of the most prevalent diseases with no perfect treatment till date. Adverse side effects and the development of chemoresistance are the imperative limiting factors associated with conventional chemotherapeutics. For this reason, there is an urgent need to find compounds that are highly safe and efficacious for the prevention and treatment of cancer. Gambogic acid (GA) is a xanthone structure extracted from the dry, brownish gamboge resin secreted from the Garcinia hanburyi tree in Southeast Asia and has inherent anti-cancer properties. In this review, the molecular mechanisms underlying the targets of GA that are liable for its effective anti-cancer activity are discussed that reveal the potential of GA as a pertinent candidate that can be appropriately developed and designed into a capable anti-cancer drug.

MiR-1202 functions as a tumor suppressor in glioma cells by targeting Rab1A

Aberrant expression of microRNAs correlates with the development and progression of human cancers by targeting downstream proteins. MiR-1202 is downregulated in ovarian cancer and clear cell papillary renal cell carcinoma; however, its role in glioma remains unknown. The purpose of this study was to determine the expression and the role of miR-1202 and to elucidate its regulatory mechanism in glioma. We used quantitative real-time polymerase chain reaction to measure miR-1202 expression in both glioma tissues and cell lines. The findings showed that the miR-1202 expression decreased dramatically in clinical glioma tissues and cell lines, and miR-1202 expression was inversely correlated with the expression of Rab1A. Using bioinformatics and luciferase reporter assays, we identified Rab1A as a novel and direct target of miR-1202. In vitro, overexpression of miR-1202 inhibited glioma cell proliferation and induced endoplasmic reticulum stress and apoptosis through targeting Rab1A, whereas suppression of miR-1202 promoted cell proliferation and inhibited endoplasmic reticulum stress and apoptosis. Similarly, silencing Rab1A with small interfering RNA also suppressed glioma cell growth and induced endoplasmic reticulum stress and apoptosis. Taken together, our data indicate that miR-1202 suppresses proliferation and induces endoplasmic reticulum stress and apoptosis through targeting and inhibiting Rab1A in glioma cells. These results suggest miR-1202 as a potential therapeutic target for the treatment of glioma patients.

LncRNA SPRY4-IT1 sponges miR-101-3p to promote proliferation and metastasis of bladder cancer cells through up-regulating EZH2

Emerging evidences have indicated that long non-coding RNAs (LncRNAs) play vital roles in cancer development and progression. Previous studies have suggested that overexpression of SPRY4-IT1 predicates poor prognosis and promotes tumor progress in several cancers. However, the underlying mechanism of SPRY4-IT1 in bladder cancer remains unknown. In this study, we found that SPRY4-IT1 knockdown induced inhibition of cell proliferation, cell migration and invasion ability, and caused promotion of apoptosis in bladder cancer both in vitro and in vivo. Mechanistically, knockdown of SPRY4-IT1 increased the expression of miR-101-3p and subsequently inhibited the expression of EZH2 at posttranscriptional level. Importantly, SPRY4-IT1 could directly interact with miR-101-3p and down-regulation of miR-101-3p efficiently reversed the suppression of EZH2 induced by SPRY4-IT1 shRNA. Thus, SPRY4-IT1 positively regulated the expression of EZH2 through sponging miR-101-3p, and played an oncogenic role in bladder cancer progression. Together, our study elucidates the role of LncRNA SPRY4-IT1 as a miRNA sponge in bladder cancer, and sheds new light on LncRNA-directed diagnostics and therapeutics in bladder cancer.

miR-15b-5p induces endoplasmic reticulum stress and apoptosis in human hepatocellular carcinoma, both in vitro and in vivo, by suppressing Rab1A

In human hepatocellular carcinoma (HCC), aberrant expression of miRNAs correlates with tumor cell proliferation, apoptosis, invasion, and migration by targeting downstream proteins. miR-15b levels are reported increased in HCC tissues; however, they negatively correlate to HCC recurrence. Our aim was to understand the reason for this phenomenon. We used the reverse transcription-polymerase chain reaction (RT-PCR) to measure miR-15b-5p expression in both HCC tissues and HCC cell lines. Our results were consistent with the report. Using bioinformatics and luciferase reporter assays, we identified Rab1A as a novel and direct target of miR-15b-5p. Inhibiting the function of Rab1A with shRab1A also inhibited the growth of HCC cells and induced endoplasmic reticulum stress (ERS) and apoptosis. Similarly, suppressing Rab1A by overexpression of miR-15b-5p also inhibited cell growth and induced ERS and apoptosis. Moreover, re-expression of Rab1A rescued the miR-15b-5p -induced ERS, apoptosis, and growth inhibition in HCC cells. In vivo assays were further performed to testify them. Taken together, our data suggest that miR-15b-5p induces ERS, apoptosis, and growth inhibition by targeting and suppressing Rab1A, acting as a tumor suppressor gene in HCC. This finding suggests a novel relation among Rabs, miRNAs, and apoptosis.

Oridonin induces apoptosis through the mitochondrial pathway in human gastric cancer SGC-7901 cells

Oridonin is one of the most important antitumor active ingredients of Rabdosia rubescens. Recently published studies from our laboratory have demonstrated that oridonin was able to arrest human gastric cancer SGC-7901 cells at G2/M phase. However, little is known about inducing apoptosis in gastric cancer. The aim of this study was to investigate the effect of oridonin on antineoplastic capability of SGC-7901 cells and the detailed molecular mechanism of oridonin-mediated intrinsic pathway of apoptosis. Cell proliferation was assessed by MTT assay while apoptosis induced by oridonin was determined by Hoechst 33342 staining assay and Annexin V/PI double staining assay. Early apoptotic rate was stained by Annexin V/PI and detected by flow cytometry. Apoptosis pathway was analyzed by western blot analysis of Bcl-2, Bax, cytochrome c and caspase-3 expression. The results showed that oridonin was able to inhibit the SGC-7901 cell proliferation, the 50% growth inhibition (IC50) was 22.74 µM. Oridonin could induce cell apoptosis of SGC-7901 cells and the early apoptotic rates induced by 0, 20, 40, 80 µmol/l oridonin were 1.53±0.67, 3.33±0.29, 84.80±0.82 and 96.43±0.51%, respectively. Western blot analysis revealed that oridonin downregulated Bcl-2 protein (the anti-apoptotic factor) and upregulated Bax protein (pro-apoptotic factor), eventually leading to a reduction in the ratio of Bcl-2/Bax proteins. Furthermore, oridonin induced the release of cytochrome c from the mitochondria to the cytosol and the activation of caspase-3. Taken together, the current study suggested that oridonin induced apoptosis in SGC-7901 cells via the mitochondrial signal pathway, which may represent one of the major mechanisms of oridonin-mediated apoptosis in SGC-7901 cells.

Deoxynivalenol induces apoptosis in PC12 cells via the mitochondrial pathway

Deoxynivalenol (DON) has broad toxicity in animals and humans. In this study the impact of DON treatment on apoptotic pathways in PC12 cells was determined. The effects of DON were evaluated on (i) typical indicators of apoptosis, including cellular morphology, cell activity, lactate dehydrogenase (LDH) release, and apoptosis ratio in PC12 cells, and on (ii) the expression of key genes and proteins related to apoptosis, including Bcl-2, Bax, Bid, cytochrome C (Cyt C), apoptosis inducing factor (AIF), cleaved-Caspase9, and cleaved-Caspase3. DON treatment inhibited proliferation of PC12 cells, induced significant morphological changes and apoptosis, promoted the release of Cyt C and AIF from the mitochondria, and increased the activities of cleaved-Caspase9 and cleaved-Caspase3. Bcl-2 expression decreased with increasing DON concentrations, in contrast to Bax and Bid, which were increased with increasing DON concentration. These data demonstrate that DON induces apoptosis in PC12 cells through the mitochondrial apoptosis pathway.

c-Jun N-terminal Kinase-Dependent Endoplasmic Reticulum Stress Pathway is Critically Involved in Arjunic Acid Induced Apoptosis in Non-Small Cell Lung Cancer Cells

Though arjunic acid, a triterpene isolated from Terminalia arjuna, was known to have antioxidant, antiinflammatory, and cytotoxic effects, its underlying antitumor mechanism still remains unclear so far. Thus, in the present study, the molecular antitumor mechanism of arjunic acid was examined in A549 and H460 non-small cell lung cancer (NSCLC) cells. Arjunic acid exerted cytotoxicity by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) assay and significantly increased sub-G1 population in A549 and H460 cells by cell cycle analysis. Consistently, arjunic acid cleaved poly (ADP-ribose) polymerase (PARP), activated Bax, and phosphorylation of c-Jun N-terminal kinases (JNK), and also attenuated the expression of pro-caspase-3 and Bcl-2 in A549 and H460 cells. Furthermore, arjunic acid upregulated the expression of endoplasmic reticulum (ER) stress proteins such as IRE1 α, ATF4, p-eIF2α, and C/EBP homologous protein (CHOP) in A549 and H460 cells. Conversely, CHOP depletion attenuated the increase of sub-G1 population by arjunic acid, and also JNK inhibitor SP600125 blocked the cytotoxicity and upregulation of IRE1 α and CHOP induced by arjunic acid in A549 and H460 cells. Overall, our findings suggest that arjunic acid induces apoptosis in NSCLC cells via JNK mediated ER stress pathway as a potent chemotherapeutic agent for NSCLC.

Ganoderma lucidum polysaccharide peptide prevents renal ischemia reperfusion injury via counteracting oxidative stress

Ganoderma lucidum polysaccharide peptide (GLPP) scavenges oxygen free radicals that are a key factor in the pathogenesis of renal ischemia reperfusion injury (RIRI). The aim of this study was to determine whether GLPP could attenuate RIRI by counteracting the oxidative stress. The mechanism involved was assessed by an in vivo mouse RIRI model and an in vitro hypoxia/reoxygenation model, and tunicamycin-stimulated NRK-52E cells were used to explore the GLPP-mediated alleviation of ER stress. Experimental results showed that renal dysfunction and morphological damage were reduced in GLPP-treated group. The imbalance of redox status was reversed and production of ROS was reduced by GLPP. RIRI-induced mitochondrial- and ER stress-dependent apoptosis were dramatically inhibited in GLPP-treated group. Intriguingly, JNK activation in the kidney with RIRI or hypoxia/reoxygenation was inhibited by GLPP. These results suggest that the protective effect of GLPP against RIRI may be due to reducing oxidative stress, alleviating the mitochondrial and ER stress-dependent apoptosis caused by excessive ROS.

Gambogic acid inhibits growth, induces apoptosis, and overcomes drug resistance in human colorectal cancer cells

The emergence of chemoresistance is a major limitation of colorectal cancer (CRC) therapies and novel biologically based therapies are urgently needed. Natural products represent a novel potential anticancer therapy. Gambogic acid (GA), a small molecule derived from Garcinia hanburyi Hook. f., has been demonstrated to be highly cytotoxic to several types of cancer cells and have low toxicity to the hematopoietic system. However, the potential role of GA in colorectal cancer and its ability to overcome the chemotherapeutic resistance in CRC cells have not been well studied. In the present study, we showed that GA directly inhibited proliferation and induced apoptosis in both 5-fluorouracil (5-FU) sensitive and 5-FU resistant colorectal cancer cells; induced apoptosis via activating JNK signaling pathway. The data, therefore, suggested an alternative strategy to overcome 5-FU resistance in CRC and that GA could be a promising medicinal compound for colorectal cancer therapy.

Methane-rich saline attenuates ischemia/reperfusion injury of abdominal skin flaps in rats via regulating apoptosis level

Background

In plastic surgery, skin damage induced by ischemia/reperfusion (I/R) is a multifactorial process that often occurs. Methane gas has been reported to be a new therapeutic gas for attenuating I/R injury. In this study, we assessed the effects of methane-rich saline (MRS) in regulating apoptosis on skin flap I/R injury.

Methods

Male Sprague–Dawley rats, 6–8 weeks old, were divided randomly into three groups: one sham surgery group (SH) and two surgery groups. After undergoing 6 h of I/R management of an abdominal skin flap, surgery groups were treated with physiological saline (I/R-P) or methane-rich saline (I/R-M). On the 3rd postoperative day, a laser Doppler flowmeter was used to measure flap blood supply, and hematoxylin and eosin (H&E) staining was used to observe morphological changes. TdT-mediated dUTP-X nick end labeling (TUNEL) staining was also used to observe early apoptosis and is presented as the percentage of TUNEL-positive cells. Moreover, pASK-1, pJNK, Bcl-2 and Bax were detected by immunohistochemical technology. Caspase-3 activity was also measured to evaluate the effects of MRS.

Results

Compared to the I/R-P group, the flaps in the I/R-M group presented a larger survival area and better blood perfusion with less inflammatory infiltration and cell apoptosis, a higher expression of Bcl-2, a lower expression of pASK-1, pJNK and Bax, and a lower caspase-3 activity.

Conclusion

According to the results, MRS attenuated I/R injury by regulating apoptosis and has the potential to be applied as a new therapy for improving skin flap survival.