Proscillaridin A Promotes Oxidative Stress and ER Stress, Inhibits STAT3 Activation, and Induces Apoptosis in A549 Lung Adenocarcinoma Cells

Unraveling the complexity of STAT3 in cancer: molecular understanding and drug discovery

Signal transducer and activator of transcription 3 (STAT3) is a transcriptional factor involved in almost all cancer hallmark features including tumor proliferation, metastasis, angiogenesis, immunosuppression, tumor inflammation, metabolism reprogramming, drug resistance, cancer stemness. Therefore, STAT3 has become a promising therapeutic target in a wide range of cancers. This review focuses on the up-to-date knowledge of STAT3 signaling in cancer. We summarize both the positive and negative modulators of STAT3 together with the cancer hallmarks involving activities regulated by STAT3 and highlight its extremely sophisticated regulation on immunosuppression in tumor microenvironment and metabolic reprogramming. Direct and indirect inhibitors of STAT3 in preclinical and clinical studies also have been summarized and discussed. Additionally, we highlight and propose new strategies of targeting STAT3 and STAT3-based combinations with established chemotherapy, targeted therapy, immunotherapy and combination therapy. These efforts may provide new perspectives for STAT3-based target therapy in cancer.

Cellular battle against endoplasmic reticulum stress and its adverse effect on health

The endoplasmic reticulum (ER) is a dynamic organelle and a reliable performer for precisely folded proteins. To maintain its function and integrity, arrays of sensory and quality control systems enhance protein folding fidelity and resolve the highest error-prone areas. Yet numerous internal and external factors disrupt its homeostasis and trigger ER stress responses. Cells try to reduce the number of misfolded proteins via the UPR mechanism, and ER-related garbage disposals systems like ER-associated degradation (ERAD), ER-lysosome-associated degradation (ERLAD), ER-Associated RNA Silencing (ERAS), extracellular chaperoning, and autophagy systems, which activates and increase the cell survival rate by degrading misfolded proteins, prevent the aggregated proteins and remove the dysfunctional organelles. Throughout life, organisms must confront environmental stress to survive and develop. Communication between the ER & other organelles, signaling events mediated by calcium, reactive oxygen species, and inflammation are linked to diverse stress signaling pathways and regulate cell survival or cell death mechanisms. Unresolved cellular damages can cross the threshold limit of their survival, resulting in cell death or driving for various diseases. The multifaceted ability of unfolded protein response facilitates the therapeutic target and a biomarker for various diseases, helping with early diagnosis and detecting the severity of diseases.

Synthesis and Biological Evaluation of 3-Amino-4,4-Dimethyl Lithocholic Acid Derivatives as Novel, Selective, and Cellularly Active Allosteric SHP1 Activators

Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1), a non-receptor member of the protein tyrosine phosphatase (PTP) family, negatively regulates several signaling pathways that are responsible for pathological cell processes in cancers. In this study, we report a series of 3-amino-4,4-dimethyl lithocholic acid derivatives as SHP1 activators. The most potent compounds, 5az-ba, showed low micromolar activating effects (EC50: 1.54–2.10 μM) for SHP1, with 7.63–8.79-fold maximum activation and significant selectivity over the closest homologue Src homology 2 domain-containing protein tyrosine phosphatase 2 (SHP2) (>32-fold). 5az-ba showed potent anti-tumor effects with IC50 values of 1.65–5.51 μM against leukemia and lung cancer cells. A new allosteric mechanism of SHP1 activation, whereby small molecules bind to a central allosteric pocket and stabilize the active conformation of SHP1, was proposed. The activation mechanism was consistent with the structure–activity relationship (SAR) data. This study demonstrates that 3-amino-4,4-dimethyl lithocholic acid derivatives can be selective SHP1 activators with potent cellular efficacy.

Nanoparticle-Mediated Delivery of STAT3 Inhibitors in the Treatment of Lung Cancer

Lung cancer is a common malignancy worldwide, with high morbidity and mortality. Signal transducer and activator of transcription 3 (STAT3) is an important transcription factor that not only regulates different hallmarks of cancer, such as tumorigenesis, cell proliferation, and metastasis but also regulates the occurrence and maintenance of cancer stem cells (CSCs). Abnormal STAT3 activity has been found in a variety of cancers, including lung cancer, and its phosphorylation level is associated with a poor prognosis of lung cancer. Therefore, the STAT3 pathway may represent a promising therapeutic target for the treatment of lung cancer. To date, various types of STAT3 inhibitors, including natural compounds, small molecules, and gene-based therapies, have been developed through direct and indirect strategies, although most of them are still in the preclinical or early clinical stages. One of the main obstacles to the development of STAT3 inhibitors is the lack of an effective targeted delivery system to improve their bioavailability and tumor targetability, failing to fully demonstrate their anti-tumor effects. In this review, we will summarize the recent advances in STAT3 targeting strategies, as well as the applications of nanoparticle-mediated targeted delivery of STAT3 inhibitors in the treatment of lung cancer.

A method establishment and comparison of in vivo lung cancer model development platforms for evaluation of tumour metabolism and pharmaceutical efficacy

BACKGROUND

Currently, the identification of accurate biomarkers for the diagnosis of patients with early-stage lung cancer remains difficult. Fortunately, metabolomics technology can be used to improve the detection of plasma metabolic biomarkers for lung cancer. In a previous study, we successfully utilised machine learning methods to identify significant metabolic markers for early-stage lung cancer diagnosis. However, a related research platform for the investigation of tumour metabolism and drug efficacy is still lacking.

HYPOTHESIS/PURPOSE

A novel methodology for the comprehensive evaluation of the internal tumour-metabolic profile and drug evaluation needs to be established.

METHODS

The optimal location for tumour cell inoculation was identified in mouse chest for the non-traumatic orthotopic lung cancer mouse model. Microcomputed tomography (micro-CT) was applied to monitor lung tumour growth. Proscillaridin A (P.A) and cisplatin (CDDP) were utilised to verify the anti-lung cancer efficacy of the platform. The top five clinically valid biomarkers, including proline, L-kynurenine, spermidine, taurine and palmitoyl-L-carnitine, were selected as the evaluation indices to obtain a suitable lung cancer mouse model for clinical metabolomics research by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

The platform was successfully established, achieving 100% tumour development rate and 0% surgery mortality. P.A and CDDP had significant anti-lung cancer efficacy in the platform. Compared with the control group, four biomarkers in the orthotopic model and two biomarkers in the metastatic model had significantly higher abundance. Principal component analysis (PCA) showed a significant separation between the orthotopic/metastatic model and the control/subcutaneous/KRAS transgenic model. The platform was mainly involved in arginine and proline metabolism, tryptophan metabolism, and taurine and hypotaurine metabolism.

CONCLUSION

This study is the first to simulate clinical metabolomics by comparing the metabolic phenotype of plasma in different lung cancer mouse models. We found that the orthotopic model was the most suitable for tumour metabolism. Furthermore, the anti-tumour drug efficacy was verified in the platform. The platform can very well match the clinical reality, providing better lung cancer diagnosis and securing more precise evidence for drug evaluation in the future.

Role of JNK, ERK, and p38 MAPK signaling pathway in protective effect of sildenafil in cyclophosphamide-induced placental injury in rats

AIMS

Chemotherapeutic agents; cyclophosphamide (CYC) is used for treatment of cancer and autoimmune diseases. Grievously, CYC is non-selective as it affects both tumor and healthy cells resulting in systemic toxicity including placenta. The present study aimed to evaluate the effect of phosphodiesterase 5 inhibitor, sildenafil (Sild) on CYC-induced placental injury in rats.

MATERIALS AND METHODS

Thirty-two female Wister rats were randomly divided into 4 experimental groups. Group 1: control pregnant group; Group 2: Sild-treated pregnant rats; Group 3: pregnant rats received CYC; Group 4: pregnant rats received Sild and CYC. Placental malondialdehyde (MDA), total nitrite/nitrate (NOx), reduced glutathione (GSH), tumor necrosis factor-α (TNF-α), platelet growth factor (PlGF), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38MAPK), extracellular signal-regulated kinase (ERK) and cleaved caspase-3 were measured. Histological changes, Nuclear Factor kappa-light-chain-enhancer of activated B (NF-κB), Connexin 43 (GJA1) and proliferating cell nuclear antigen (PCNA) immuno-expressions were also evaluated.

KEY FINDINGS

CYC showed significant decrease in placental GSH, NOx, PlGF, GJA1 and PCNA immuno-expressions but significant increase in placental MDA, TNF-α, JNK, P38MAPK, ERK, caspase-3 and NF-kB immuno-expression. Sild showed significant improvement in all oxidative, inflammatory and apoptotic parameters.

SIGNIFICANCE

Sild is a promising protective drug against placental injury induced by CYC through antagonizing MAPK (JNK, ERK, and p38) signaling pathway with anti-oxidant, anti-inflammatory and anti-apoptotic effects.

Effects of Long Noncoding RNA H19 on Isoflurane-Induced Cognitive Dysregulation by Promoting Neuroinflammation

INTRODUCTION

Isoflurane (ISO) may cause neuronal apoptosis and synaptic disorder during development, and damage long-term learning and memory function. This observation aimed to study the function of H19 in vitro and in vivo tests and the further mechanism was identified.

METHODS

ISO cell models and rat models were established and reactive oxygen species (ROS) identified. The viability and apoptosis of HT22 cells were detected by the MTT and flow cytometer. Morris water maze test was conducted to analyze the neurotoxicity of ISO on spatial learning and memory ability. Quantitative PCR was the method to verify the expression of H19. The concentration of inflammatory indicators was identified by enzyme-linked immunosorbent assay.

RESULTS

1.5% and 2% ISO led to the neurotoxicity of HT22 cells and increased expression of H19. Silenced H19 meliorated these adverse impacts of ISO. Interference of H19 exerted neuroprotective roles by repressing modified neurological severity score, inhibiting escape latency, elevating distance and time of target area, and controlling ROS and inflammation. MiR-17-5p might be a promising competing endogenous RNA of H19. The expression of miR-17-5p was reduced in the ISO group and reversed by the absence of H19.

CONCLUSION

Our results of in vitro and in vivo assay indicated that the absence of HT22 is a neuroprotective regulator of cognition and inflammation by accumulating miR-17-5p.

TWIST2 inhibits EMT and induces oxidative stress in lung cancer cells by regulating the FGF21-mediated AMPK/mTOR pathway

Twist related protein 2 (TWIST2) plays an important role in bone development, tumorigenesis, tumour progression and epithelial mesenchymal transition (EMT). At present, there are few reports about the role of TWIST2 in lung cancer, which need to be further explored. Therefore, the purpose of this study is to explore the role and molecular mechanism of TWIST2 in the occurrence and development of lung cancer. The expression of TWIST2 in tissues of patients and cell lines was measured using RT-qPCR and western blotting. MTT and CCK8 assays were used to detect cell proliferation and viability. Western blotting was used to measure the expression of EMT-related proteins, including E-cadherin, N-cadherin, Vimentin and Slug. The results revealed that TWIST2 is lowly expressed in the tissues of lung cancer patients and cell lines. Further studies found that overexpression of TWIST2 significantly induced apoptosis and promoted the expression of E-cadherin, as well as inhibiting the expression of N-cadherin, Vimentin and Slug. More importantly, TWIST2 induced oxidative stress in lung cancer cells. In addition, TWIST2 regulated the FGF21 and AMPK/mTOR signalling pathway, which is involved in the molecular mechanism of the gene in lung cancer cells. We suggest that the mechanism of TWIST2 inhibition of the progression of lung cancer is by regulating the FGF21-mediated AMPK/mTOR signalling pathway.

Antioxidant and Cytotoxic Effects and Identification of Ophiocordyceps sinensis Bioactive Proteins Using Shotgun Proteomic Analysis

RESEARCH BACKGROUND

Ophiocordyceps sinensis, a highly valued medicinal fungus, is close to extinction due to overexploitation. Successful cultivation of O. sinensis fruiting body (OCS02®) shows that the cultivar has a promising nutritional value and numerous bioactive compounds. Antioxidant and antiproliferative properties and biologically active proteins of the OCS02® are investigated for possible development into nutraceuticals.

EXPERIMENTAL APPROACH

The chemical composition of the OCS02® cold water extract was determined, and the antioxidant activities were examined using ferric reducing, DPPH• and O2 •- scavenging assays. Tetrazolium dye (MTT) cytotoxic assay was performed to assess the antiproliferative activity of the extract. Bioactive proteins in the active fraction of the extract were identified using liquid chromatography (LC) and tandem-mass spectrometry (MS/MS).

RESULTS AND CONCLUSIONS

The OCS02® extract exhibited strong O2 •- scavenging (expressed as Trolox equivalents (18.4±1.1) mol/g) and potent cytotoxic activities against adenocarcinomic human alveolar basal epithelial (A549) cells (IC50=(58.2±6.8) µg/mL). High molecular mass polysaccharides, proteins and protein-polysaccharide complexes could have contributed to the antioxidant and cytotoxic selectivity of the OCS02®. LC-MS/MS analysis identified several potential cytotoxic proteases and an oxalate decarboxylase protein which may exhibit protection effects on kidneys.

NOVELTY AND SCIENTIFIC CONTRIBUTIONS

The findings demonstrate the potential of OCS02® to be developed into functional food due to its promising superoxide anion radical scavenging capacity, cytotoxic effect and presence of biopharmaceutically active proteins.

Chinese herbal medicine: Fighting SARS-CoV-2 infection on all fronts

ETHNOPHARMACOLOGICAL RELEVANCE

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19), a highly pathogenic virus that has spread rapidly across the entire world. There is a critical need to develop safe and effective drugs, especially broad-spectrum antiviral and organ protection agents in order to treat and prevent this dangerous disease. It is possible that Chinese herbal medicine may play an essential role in the treatment of patients with SARS-CoV-2 infection.

AIM OF THE REVIEW

We aim to review the use of Chinese herbal medicine in the treatment of COVID-19 both in vitro and in clinical practice. Our goal was to provide a better understanding of the potential therapeutic effects of Chinese herbal medicine and to establish a "Chinese protocol" for the treatment of COVID-19.

MATERIALS AND METHODS

We systematically reviewed published research relating to traditional Chinese herbal medicines and the treatment of SARS-CoV-2 from inception to the 6^th January 2021 by screening a range of digital databases (Web of Science, bioRxiv, medRxiv, China National Knowledge Infrastructure, X-MOL, Wanfang Data, Google Scholar, PubMed, Elsevier, and other resources) and public platforms relating to the management of clinical trials. We included the active ingredients of Chinese herbal medicines, monomer preparations, crude extracts, and formulas for the treatment of COVID-19.

RESULTS

In mainland China, a range of Chinese herbal medicines have been recognized as very promising anti-SARS-CoV-2 agents, including active ingredients (quercetagetin, osajin, tetrandrine, proscillaridin A, and dihydromyricetin), monomer preparations (xiyanping injection, matrine-sodium chloride injection, diammonium glycyrrhizinate enteric-coated capsules, and sodium aescinate injection), crude extracts (Scutellariae Radix extract and garlic essential oil), and formulas (Qingfei Paidu decoction, Lianhuaqingwen capsules, and Pudilan Xiaoyan oral liquid). All these agents have potential activity against SARS-CoV-2 and have attracted significant attention due to their activities both in vitro and in clinical practice.

CONCLUSIONS

As a key component of the COVID-19 treatment regimen, Chinese herbal medicines have played an irreplaceable role in the treatment of SARS-CoV-2 infection. The "Chinese protocol" has already demonstrated clear clinical importance. The use of Chinese herbal medicines that are capable of inhibiting SARS-Cov-2 infection may help to address this immediate unmet clinical need and may be attractive to other countries that are also seeking new options for effective COVID-19 treatment. Our analyses suggest that countries outside of China should also consider protocols involving Chinese herbal medicines combat this fast-spreading viral infection.

Shikonin Derivatives from Onsoma visianii Decrease Expression of Phosphorylated STAT3 in Leukemia Cells and Exert Antitumor Activity

Antitumor effects of shikonins on chronic lymphocytic leukemia (CLL) and B-cell prolymphocytic leukemia (B-PLL) are mostly unexplored. The antitumor activity of shikonins, isolated from Onosma visianii Clem (Boraginaceae), in BCL1, mouse CLL cells and JVM-13, human B-PLL cells was explored in this study. The cytotoxicity of shikonin derivatives was measured by an MTT test. Cell death, proliferation, cell cycle, and expression of molecules that control these processes were analyzed by flow cytometry. Expression of STAT3-regulated genes was analyzed by real-time q-RT-PCR (Quantitative Real-Time Polymerase Chain Reaction). The antitumor effects of shikonin derivatives in vivo were analyzed, using flow cytometry, by detection of leukemia cells in the peripheral blood and spleens of mice intravenously injected with BCL1 cells. The two most potent derivatives, isobutyrylshikonin (IBS) and α-methylbutyrylshikonin (MBS), induced cell cycle disturbances and apoptosis, inhibited proliferation, and decreased expression of phospho-STAT3 and downstream-regulated molecules in BCL1 and JVM-13 cells. IBS and MBS decreased the percentage of leukemia cells in vivo. The link between the decrease in phosphorylated STAT3 by MBS and IBS and BCL1 cell death was confirmed by detection of enhanced cell death after addition of AG490, an inhibitor of Jak2 kinase. It seems that IBS and MBS, by decreasing STAT3 phosphorylation, trigger apoptosis, inhibit cell proliferation, and attenuate leukemia cell stemness.

Identification of Molecular Markers Associated With the Pathophysiology and Treatment of Lupus Nephritis Based on Integrated Transcriptome Analysis

Lupus nephritis (LN) is a well-known complication of systemic lupus erythematosus and is its leading cause of morbidity and mortality. Our study aimed to identify the molecular markers associated with the pathophysiology and treatment of LN. The renal tissue gene expression profiles of LN patients in the GSE32591 dataset were downloaded as a discovery cohort from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified; weighted gene co-expression network analysis (WGCNA) was used to identify the co-expression modules of DEGs; and gene function enrichment analysis, molecular crosstalk analysis, and immune cell infiltration analysis were performed to explore the pathophysiological changes in glomeruli and tubulointerstitia of LN patients. The crosstalk genes were validated in another RNA-sequencing cohort. DEGs common in RNA-sequencing dataset and GSE32591 were uploaded to the Connectivity Map (CMap) database to find prospective LN-related drugs. Molecular docking was used to verify the targeting association between candidate small molecular compounds and the potential target. In all, 420 DEGs were identified; five modules and two modules associated with LN were extracted in glomeruli and tubulointerstitia, respectively. Functional enrichment analysis showed that type I interferon (IFN) response was highly active, and some biological processes such as metabolism, detoxification, and ion transport were impaired in LN. Gene transcription in glomeruli and tubulointerstitia might affect each other, and some crosstalk genes, such as IRF7, HLA-DRA, ISG15, PSMB8, and IFITM3, play important roles in this process. Immune cell infiltration analysis revealed that monocytes and macrophages were increased in glomeruli and tubulointerstitia, respectively. CMap analysis identified proscillaridin as a possible drug to treat LN. Molecular docking showed proscillaridin forms four hydrogen bonds with the SH2 domain of signal transducer and activator of transcription 1 (STAT1). The findings of our study may shed light on the pathophysiology of LN and provide potential therapeutic targets for LN.

Cyclosporin A protects JEG-3 cells against oxidative stress-induced apoptosis by inhibiting the p53 and JNK/p38 signaling pathways

BACKGROUND

Trophoblast cells are required for the establishment of pregnancy and fetal development. Apoptosis is an essential feature for trophoblast invasion. Uncontrolled trophoblast apoptosis is related to some complicate pregnancies. Oxidative stress (OS) is an important inducer of trophoblast apoptosis. Cyclosporin A (CsA) has been shown to promote the activity of trophoblast cells and reduce OS-induced oxidative injury. We investigated the role and mechanism of CsA in oxidative stress-induced trophoblast cell apoptosis.

METHODS

JEG-3 cells were cocultured with H₂O₂ and CsA. Cell viability and morphology were measured by MTT assay and DAPI staining. Cell apoptosis was tested with annexin V/PI staining. The expression of Bcl-2-associated X protein (Bax), B-cell lymphoma/leukemia-2 (Bcl-2), cleaved poly (ADP-ribose) polymerase (PARP) and pro-caspase-3 was assayed by western blotting. The protein expression and phosphorylation of p53 and mitogen-activated protein kinase (MAPK) kinases (JNK, ERK1/2 and p38) were examined by western blotting.

RESULTS

CsA increased the viability, alleviated morphological injury and reduced cell apoptosis of the H₂O₂-treated JEG-3 cells. CsA also attenuated the activation of p53, decreased the expression of Bax and cleavage of PARP, and increased the expression of Bcl-2 and pro-caspase-3 in the JEG-3 treated with H₂O₂. Furthermore, CsA reduced the activation of JNK and P38 but had no significant effect on the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the H₂O₂-treated JEG-3 cells. Promoting the activation of JNK and p38 impaired the protective effect of CsA on OS-induced trophoblast apoptosis.

CONCLUSIONS

These results suggested that CsA protected trophoblast cells from OS-induced apoptosis via the inhibition of the p53 and JNK/p38 signaling pathways.

Hispidulin: A novel natural compound with therapeutic potential against human cancers

Cancer is one of the most devastating disease and leading cause of death worldwide. The conventional anticancer drugs are monotarget, toxic, expensive and suffer from drug resistance. Development of multi-targeted drugs from natural products has emerged as a new paradigm to overcome aforementioned conventionally encountered obstacles. Hispidulin (HIS), is a biologically active natural flavone with versatile biological and pharmacological activities. The anticancer, antimutagenic, antioxidative and anti-inflammatory properties of HIS have been reported. The aim of this review is to summarize the findings of several studies over the last few decades on the anticancer activity of HIS published in various databases including PubMed, Google Scholar, and Scopus. HIS has been shown to reduce the growth of cancer cells by inducing apoptosis, arresting cell cycle, inhibiting angiogenesis, invasion and metastasis via modulating multiple signaling pathways implicated in cancer initiation and progression. Multitargeted anticancer activity of HIS remains the strongest point for developing it into potential anticancer drug. We also highlighted the natural sources, anticancer mechanism, cellular targets, and chemo-sensitizing potential of HIS. This review will provide bases for design and conduct of further pre-clinical and clinical trials to develop HIS into a lead structure for future anticancer therapy.

Heat shock protein B8 promotes proliferation and migration in lung adenocarcinoma A549 cells by maintaining mitochondrial function

Heat shock protein B8 (HSPB8) impacts on tumor proliferation and migration of malignancy. However, the role of HSPB8 in lung adenocarcinoma (LUAC) remains unclear. The aim of this study, therefore, was to clarify whether HSPB8 could bring benefits to proliferation and migration of LUAC and its underlying mechanisms. The expression of HSPB8 was first evaluated by immunohistochemistry in 35 LUAC samples. Then, A549 lung adenocarcinoma cells were transfected with pcDNA-HSPB8 or si-HSPB8 to induce HSPB8 overexpression and silence. Cellular activity was evaluated with a Cell Counting Kit-8 (CCK-8) assay. Cell proliferation and migration were observed by EdU assay and scratch assay. Mitochondria-specific reactive oxygen species (mtROS) and membrane potential were measured using MitoSOX Red probe and JC-1 staining. Superoxide dismutase (SOD) activities and malondialdehyde (MDA) level were measured using commercial kits, respectively. HSPB8 protein, mitochondrial fusion protein MFN2 and mitochondrial fission protein p-Drp1/Drp1 were measured using western blot. Compared with the normal tissues, the expression of HSPB8 protein was higher in LUAC tissues and upregulation of HSPB8 protein was related to tumor size and tumor location. Furthermore, HSPB8 overexpression aggravated cell proliferation and migration of A549 cells. Mechanistically, HSPB8 suppressed mitochondrial impairment, leading to promoting the progress of A549 lung adenocarcinoma cells. These data demonstrate that HSPB8 plays an important role in progression of LUAC and may be a new target to treat LUAC.

Inhibition of JNK-Mediated Autophagy Promotes Proscillaridin A- Induced Apoptosis via ROS Generation, Intracellular Ca+2 Oscillation and Inhibiting STAT3 Signaling in Breast Cancer Cells

Breast cancer is the most heterogenous cancer type among women across the world. Despite concerted efforts, breast cancer management is still unsatisfactory. Interplay between apoptosis and autophagy is an imperative factor in categorizing therapeutics for cancer treatment. Proscillaridin A (PSD-A), a well-known cardiac glycoside used for cardiac arrest and arrythmias, has been unveiled in many cancer types but the underlying mechanism for apoptosis and autophagy in breast cancer is not fully understood. In our study, PSD-A restricted cell growth, inhibited STAT3 activation and induced apoptosis and autophagy in breast cancer cells via ROS generation and Ca⁺² oscillation. Pretreatment of NAC and BAPTA-AM restored PSD-A induced cellular events in breast cancer cells. PSD-A induced apoptosis via DNA fragmentation, caspase-cascade activation, PARP cleavage, mitochondrial dysfunction, Bax/Bcl-2 proteins modulation and ER chaperone GRP78 inhibition along with decreased phosphorylation of ERK1/2. Inhibition of STAT3 activation was found to be associated with decreased phosphorylation of SRC. Moreover, PSD-A induced events of autophagy i.e. conversion of LC3-I to LC3-II, and Atg3 expression via JNK activation and decreased mTOR and AKT phosphorylation. In this study, pretreatment of SP600125, a JNK inhibitor, reduced autophagy and enhanced STAT3 inhibition and apoptosis. Additionally, SB203580, a commercial p38 inhibitor, stimulated STAT3 activation and improved autophagic events rate in breast cancer cells, displaying the role of the MAPK signaling pathway in interplay between apoptosis and autophagy. Our data suggest that the rate of apoptotic cell death is improved by blocking JNK-induced autophagy in PSD-A treated MCF-7 and MDA-MB-231 breast cancer cells.

Molecular mechanisms of bufadienolides and their novel strategies for cancer treatment

Bufadienolides are cardioactive C24 steroids with an α-pyrone ring at position C17. In the last ten years, accumulating studies have revealed the anticancer activities of bufadienolides and their underlying mechanisms, such as induction of autophagy and apoptosis, cell cycle disruption, inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and stemness, and multidrug resistance reversal. As Na⁺/K⁺-ATPase inhibitors, bufadienolides have inevitable cardiotoxicity. Short half-lives, poor stability, low plasma concentration and oral bioavailability in vivo are obstacles for their applications as drugs. To improve the drug potency of bufadienolides and reduce their side effects, prodrug strategies and drug delivery systems such as liposomes and nanoparticles have been applied. Therefore, systematic and recapitulated information about the antitumor activity of bufadienolides, with special emphasis on the molecular or cellular mechanisms, prodrug strategies and drug delivery systems, is of high interest. Here, we systematically review the anticancer effects of bufadienolides and the molecular or cellular mechanisms of action. Research advancements regarding bufadienolide prodrugs and their tumor-targeting delivery strategies are critically summarized. This work highlights recent scientific advances regarding bufadienolides as effective anticancer agents from 2011 to 2019, which will help researchers to understand the molecular pathways involving bufadienolides, resulting in a selective and safe new lead compound or therapeutic strategy with improved therapeutic applications of bufadienolides for cancer therapy.

Implications for glycosylated compounds and their anti-cancer effects

Glycosylated compounds are major secondary metabolites of plants, which have various therapeutic effects on human diseases, by acting as anti-cancer, antioxidant, and anti-inflammatory agents. Glycosylation increases stability, bioactivity, and solubility of compounds and improves their pharmacological properties. Two well-known examples of glycosylated compounds include cardiac and flavonoid, the anti-tumor activities of which have been emphasized by several studies. However, little is known about their role in the treatment or prevention of cancer. In this review, recent studies on anti-tumor properties of cardiac and flavonoid glycosides, and their mechanisms of action, have been investigated. More specifically, this review is aimed at focusing on the multifactorial properties of cardiac and flavonoid compounds as well as their correlation with signaling pathways in the treatment of cancer.

Brevilin A induces ROS-dependent apoptosis and suppresses STAT3 activation by direct binding in human lung cancer cells

Sesquiterpene lactones have been shown to be promising leads for anticancer drug development. Brevilin A (BLN-A), a sesquiterpene lactone compound of Centipeda minima has been shown to exhibit anticancer effects against various cancer cells. However, the anticancer mechanism and cellular targets of BLN-A remain elusive. Here in this study, BLN-A inhibits proliferation and induces cell morphological changes in A549 and NCI-H1650 non-small cell lung cancer cells in a dose-dependent manner. Moreover, BLN-A increased ROS generation and bax/bcl-2 ratio while decreased intracellular glutathione (GSH), and mitochondrial membrane potential which resulted in induction of apoptosis as evident by annexin-V/FITC staining, caspase-3 activation and PARP cleavage. Supplementation of cells with NAC (ROS Scavenger) effectively protected the cells from BLN-A-induced apoptosis. Finally, BLN-A inhibited constitutive as well as IL-6- and EGF-induced STAT3 activation at Tyr705. Using molecular docking and SPR analyses, we found that BLN-A directly binds with STAT3 and thereby inhibits its activation. Knocking down of STAT3 by stable transfection with shRNA suppressed growth and augmented cytotoxicity of BLN-A, indicating the key role of STAT3 in BLN-A-mediated apoptosis. Cumulative findings suggest that BLN-A is a promising lead structure for developing it into a potent STAT3 inhibitor and therapeutic agent against NSCLC as well.

Hispidulin exhibits potent anticancer activity in vitro and in vivo through activating ER stress in non‑small‑cell lung cancer cells

Hispidulin is a medicinal natural compound isolated from S. involucrata, which exhibits potent anticancer properties. However, there are few reports on its effects on lung cancer cells. Therefore, the current study investigated the effects of hispidulin on cell viability and apoptosis in human non‑small‑cell lung cancer (NSCLC) cell lines NCI‑H460 and A549 in vitro and in vivo. Methyl thiazolyl tetrazolium, colony formation assay, Hoechst 33342 staining, flow cytometry and western blotting were performed on Human NCI‑H460 and A549 cells. A mouse xenograft model was also established using NCI‑H460 cells. The results showed that the growth of NCI‑H460 and A549 cells was inhibited, while apoptosis was promoted by hispidulin via increased generation of reactive oxygen species (ROS) in a dose‑dependent manner. Furthermore, hispidulin triggered apoptosis in NSCLC cells through upregulating the expression of cleaved caspase‑3 and cleaved poly [ADP‑ribose] polymerase. All these effects were reversed upon pretreatment with glutathione, a selective ROS inhibitor. In addition, endoplasmic reticulum stress (ER stress) in NCI‑H460 cells was activated by hispidulin. Pretreatment with tauroursodeoxycholic acid, a specific ER stress inhibitor, effectively reduced the cell apoptosis induced by hispidulin. In conclusion, hispidulin induces ROS‑mediated apoptosis via activating the ER stress pathway. The current study provides theoretical basis for the antitumor effect of hispidulin in NSCLC.

Downregulation of BIS sensitizes A549 cells for digoxin-mediated inhibition of invasion and migration by the STAT3-dependent pathway

Digoxin, a compound of the cardiac glycoside family, was originally prescribed for heart failure but has recently been rediscovered for its potent antitumor activity. However, it has a narrow therapeutic margin due to its cardiotoxicity, limiting its safe use as an antitumor agent in clinical practice. To widen its therapeutic margin, we investigated whether the antitumor effect of digoxin is potentiated by the depletion of BCL-2-interacting cell death suppressor (BIS) in A549 lung cancer cells. BIS is a multifunctional protein that is frequently overexpressed in most human cancers including lung cancer. Our results demonstrated that the inhibitory potential of digoxin on the migratory behavior of A549 cells is significantly enhanced by BIS depletion as assessed by transwell assay and collagen-incorporated 3D spheroid culture. Western blotting revealed that combination treatment significantly reduces p-STAT3 expression. In addition, a STAT3 inhibitor substantially suppressed the aggressive phenotypes of A549 cells. Thus, our results suggest that loss of STAT3 activity is a possible molecular mechanism for the synergistic effect of digoxin and BIS depletion. Our findings suggest the sensitizing role of BIS silencing to reduce the dose of digoxin for treatment of lung cancer with a high metastatic potential.

Brevilin A Inhibits STAT3 Signaling and Induces ROS-Dependent Apoptosis, Mitochondrial Stress and Endoplasmic Reticulum Stress in MCF-7 Breast Cancer Cells

Purpose

Breast cancer is the most common malignancy among women across the globe. Despite concerted efforts to improve the prevailing treatment modalities, the overall prognosis of breast cancer remains unsatisfactory. Recently, antiproliferative activity of Brevilin A (Brv-A), a sesquiterpene lactone compound of Centipeda minima, has been unveiled in various cancer types. Here, we have explored anticancer activity of Brv-A in MCF-7 breast carcinoma cells by targeting various pathways.

Materials and Methods

Cell proliferation rate was determined by CCK-8 and clonogenic assay. Cellular morphological changes were observed under phase contrast microscope while calcein-AM and PI was used for live/dead assay. Cell cycle assay was performed by flow cytometry. Apoptotic cell percentage was determined by Hoechst 33258 staining and flow cytometric analysis. ROS generation and mitochondrial membrane potential were measured using commercially available kits while protein expression was measured by Western blotting.

Results

In our study, Brv-A exerted antiproliferative effect through mitotic arrest at G₂/M phase of cell cycle and induced apoptosis in MCF-7 cells in a dose-dependent manner. Induction of apoptosis by Brv-A was found to be associated with ROS generation by targeting NOX2 and NOX3, mitochondrial dysfunction (MMP dissipation and Bcl-2 family proteins modulation), DNA fragmentation, JNK and p38 MAPK activation, endoplasmic reticulum (ER) stress by increasing Bip/GRP78, ATF4 and CHOP protein expressions and inhibition of STAT3 activation via decreased phosphorylation of JAK2 and SRC. Pretreatment of NAC, a ROS scavenger, partially reversed the aforesaid cellular events indicating ROS generation as the primary event to modulate cellular targets for induction of apoptosis. Besides, Brv-A has also been documented for inhibition of cell migration via decrease in COX-2 and MMP-2 expression.

Conclusion

Taken together, Brv-A induces G₂/M phase arrest, ROS-dependent apoptosis, ER stress, mitochondrial dysfunction and inhibits STAT3 activation in MCF-7 cells signifying it to be one of the potential anticancer therapeutics in future.

Proscillaridin A induces apoptosis and inhibits the metastasis of osteosarcoma in vitro and in vivo

The side effects of chemotherapy, drug resistance, and tumor metastasis hinder the development of treatment for osteosarcoma, leading to poor prognosis of patients with the disease. Proscillaridin A, a kind of cardiac glycoside, has been proven to have anti-proliferative properties in many malignant tumors, but the efficacy of the drug in treating osteosarcoma is unclear. In the present study, we assessed the effects of Proscillaridin A on osteosarcoma and investigated its underlying action mechanism. The cell cytotoxicity assay showed that Proscillaridin A significantly inhibited the proliferation of 143B cells in a dose- and time-dependent manner. Also, flow cytometry and invasion assay revealed that Proscillaridin A induced apoptosis and reduced 143B cell motility. Western blotting and PCR were used to detect the expressions of Bcl-xl and MMP2 and showed that mRNA/protein expression levels decreased significantly in Proscillaridin A-treated osteosarcoma cells. Using a mouse xenograft model, we found that Proscillaridin A treatment significantly inhibited tumor growth and lung metastasis in vivo and decreased the expression levels of Bcl-xl and MMP2. No noticeable side effect was observed in the liver, kidney, and hematological functions. Conclusively, Proscillaridin A suppressed proliferation, induced apoptosis, and inhibited 143B cell metastasis in vitro and in vivo, and these effects could be mediated by downregulating the expressions of Bcl-xl and MMP2.

The Superior Antitumor Effect of Self-Assembled Paclitaxel Nanofilaments for Lung Cancer Cells

OBJECTIVES

Paclitaxel (Ptx) has been regarded as one of the most effective chemotherapeutic drugs for lung cancers. Increasing studies focused on the nano-delivery system of Ptx due to its poor solubility and hypersensitivity. The aim of the recent study was to investigate the antitumor effects of self-assembled Ptx nano-filaments for lung cancer cells.

METHODS

In the present study, we designed and synthesized novel Ptx-loaded nano-filaments through conjugation of Ptx and succinic acid (SA) (Ptx-SA, P-NFs). Non-small cell lung cancer (NSCLC) A549 and H460 cells were used for detecting the antitumor effects of P-NFs, including cytotoxicity, apoptosis, and migration. Western blotting was performed for analyzing mechanism.

RESULTS

P-NFs nano-filaments exerted superior antitumor effects against NSCLC cells compared with free Ptx using cytotoxicity tests. Furthermore, P-NFs nano-filaments were much more effective in inducing NSCLC cells apoptosis and inhibiting A549 cells migration than free Ptx. To elucidate the underlying mechanisms, the expression of apoptotic and endoplasmic reticulum (ER) stress proteins was detected. The results indicated that P-NFs nano-filaments enhanced the expression of bax/bcl-2, protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), phospho- c-Jun N-terminal kinase (p-JNK), and C/EPB homologous protein (CHOP), which suggested that the strong antitumor effect of P-NFs nano-filaments may be partially attributed to the activation ER stress.

CONCLUSION

The current work demonstrated that P-NFs nano-filaments showed superior cytotoxicity of lung cancer cells, highlighting a novel profile of nano-filaments delivery systems as potential strategies for facilitating the therapeutic efficacy of Ptx in lung cancer treatment.

Scutellarin suppresses proliferation and promotes apoptosis in A549 lung adenocarcinoma cells via AKT/mTOR/4EBP1 and STAT3 pathways

Background

Scutellarin (SCU), a flavonoid isolated from Erigeron breviscapus (Vant.) Hand.‐Mazz., increases autophagy and apoptosis in the adenocarcinoma A549 cell line, which is resistant to cisplatin. However, whether SCU alone has antitumor activity against non‐small cell lung cancer (NSCLC) is unknown.

Methods

Cell Counting Kit‐8, flow cytometry, colony formation, Hoechst 33258 staining, and Western blot analyses were used to examine the proliferation and apoptosis of A549 cells treated with SCU and the possible molecular mechanisms.

Results

The cell viability assay indicated that SCU markedly suppressed the proliferation of A549 cells in concentration and time‐dependent manners. SCU caused significant G0/G1 phase arrest and apoptosis, as evidenced by flow cytometric analyses, Hoechst 33258 staining, and Western blot analyses of cyclin D1, cyclin E, BCL‐2, cleaved‐caspase‐3, and BAX. Furthermore, SCU treatment reduced the level of pan‐AKT, phosphorylated (p)‐mTOR, mTOR, BCL‐XL, STAT3, and p‐STAT3, and increased the level of 4EBP1.

Conclusions

SCU can suppress proliferation and promote apoptosis in A549 cells through AKT/mTOR/4EBP1 and STAT3 pathways. This suggests that SCU may be developed into a promising antitumor agent for treating NSCLC.

Anticancer effects and underlying mechanism of Colchicine on human gastric cancer cell lines in vitro and in vivo

The present study investigated the effects of Colchicine on gastric carcinoma (GC) cells and explored its possible mechanisms underlying such effects. The results of MTT and colony formation assays showed that Colchicine (2, 5, and 10 ng/ml) markedly inhibited the proliferation of AGS and NCI-N87 cells in a dose-dependent manner. It also led to a reduction in cell migration in both GC cells as determined by Transwell migration assay. Mover, data form Hoechst 33342 staining and flow cytometry assay indicated that Colchicine (2, 5, and 10 ng/ml) promoted the apoptosis of NCI-N87 cells. In addition, the release of cytochrome c, the activation of bax, and the inhibition of bcl-2 were observed in NCI-N87 cells treated with Colchicine. Furthermore, the in vivo experiment further confirmed that Colchicine administration remarkably suppressed the tumor growth in nude mice via induction of apoptosis at 0.05 and 0.1 mg/kg. In addition, no visible toxicity was observed in liver and renal tissue of mice. This finding suggests that Colchicine-induced apoptosis is associated with caspase-3-mediated mitochondrial apoptotic pathways.

Isoalantolactone induces apoptosis through ROS-mediated ER stress and inhibition of STAT3 in prostate cancer cells

Background

Prostate cancer is one of the most commonly diagnosed cancers in men worldwide. Currently available therapies for metastatic prostate cancer are only marginally effective. Therefore, new therapeutic agents are urgently needed to improve patient outcome. Isoalantolactone (IATL), an active sesquiterpene naturally present in many vegetables and medicinal plants, is known to induce cell death and apoptosis in various cancer cell lines. Nevertheless, antitumor mechanisms initiated by IATL in cancer cells have not been fully defined.

Methods

Cell apoptosis and cellular ROS levels were analyzed by flow cytometry. Western blot and qRT-PCR were used to analyze the protein and mRNA levels of indicated molecules, respectively. Nude mice xenograft model was used to test the effects of IATL on prostate cancer cell growth in vivo.

Results

In this study, we found that IATL dose-dependently inhibited cancer cell growth and induced apoptosis in PC-3 and DU145 cells. Mechanistically, our data found that IATL induced reactive oxygen species (ROS) production, resulting in the activation of endoplasmic reticulum stress pathway and eventually cell apoptosis in prostate cancer cells. IATL also decreased the protein expression levels of p-STAT3 and STAT3, and the effects of IATL were reversed by pretreatment with N-acetyl-L-cysteine (NAC). In vivo, we found that IATL inhibited the growth of prostate cancer xenografts without exhibiting toxicity. Treatment of mice bearing human prostate cancer xenografts with IATL was also associated with induction of ER stress and inhibtion of STAT3.

Conclusion

In summary, our results unveil a previously unrecognized mechanism underlying the biological activity of IATL, and provide a novel anti-cancer candidate for the treatment of prostate cancer.

Brevilin A promotes oxidative stress and induces mitochondrial apoptosis in U87 glioblastoma cells

Background

Sesquiterpene lactones are plant-derived, natural, bioactive molecules often used against inflammatory diseases in traditional Chinese medicines. Recently, sesquiterpene lactones have been reported to exhibit potent anticancer activity. In the present study, we have investigated the anticancer activity of Brevilin A, a sesquiterpene lactone component of Centipeda minima, against U87 glioblastoma cells.

Materials and methods

The cell proliferation was determined by MTT assay. Cell morphological changes were observed by phase-contrast microscopy. Flow cytometry was used to measure apoptosis. Glutathione (GSH), ROS generation, and mitochondrial membrane potential were measured using commercially available kits. The expression of proteins was measured by Western blotting analysis.

Results

Brevilin A inhibited the proliferation of, and induced severe morphological changes and apoptotic cell death in, U87 glioblastoma cells in a dose-dependent manner. Further mechanistic study revealed that Brevilin A induces oxidative stress, as evident from ROS generation, GSH depletion, and increased phosphorylation of stress-activated proteins p38 and JNK. Furthermore, Brevilin A bcl-xl/bak ratio, decreased mitochondrial membrane potential and induced cytochrome c release from mitochondria into cytosol in a dose-dependent manner. Finally, Brevilin A decreased the expression of Xiap and increased the expression of cleaved forms of caspase-9 and -3 and PARP in a dose-dependent manner.

Conclusion

Collective findings demonstrated that Brevilin A is a potent, anticancer, bioactive molecule and it effectively induces apoptosis in U87 glioblastoma cells, which is associated with induction of oxidative stress and mitochondrial dysfunction.

Oxidative stress-modulating drugs have preferential anticancer effects - involving the regulation of apoptosis, DNA damage, endoplasmic reticulum stress, autophagy, metabolism, and migration

To achieve preferential effects against cancer cells but less damage to normal cells is one of the main challenges of cancer research. In this review, we explore the roles and relationships of oxidative stress-mediated apoptosis, DNA damage, ER stress, autophagy, metabolism, and migration of ROS-modulating anticancer drugs. Understanding preferential anticancer effects in more detail will improve chemotherapeutic approaches that are based on ROS-modulating drugs in cancer treatments.

Proscillaridin A induces apoptosis, inhibits STAT3 activation and augments doxorubicin toxicity in prostate cancer cells

Cardiac glycosides are natural compounds used for the treatment of congestive heart failure and cardiac arrhythmias. Recently, they have been reported to exhibit anticancer activity. Proscillaridin A (PSN-A), a cardiac glycoside constituent of Urginea maritima has been shown to exhibit anticancer activity. However, the cellular targets and anticancer mechanism of PSN-A in various cancers including prostate cancer remain largely unexplored. In the present study, we have shown that PSN-A inhibits proliferation and induces apoptosis in prostate cancer cells in a dose-dependent manner. Further mechanistic study have shown that anticancer activity of PSN-A in prostate cancer cells is associated with ROS generation, Bcl-2 family proteins modulation, mitochondrial membrane potential disruption and ultimately activation of caspase-3 and cleavage of PARP. Moreover, we found that PSN-A inhibits JAK2/STAT3 signaling and augments doxorubicin toxicity in prostate cancer cells. Of note, LNCaP cells were found to be more sensitive to PSN-A treatment as compared to DU145 cells. Taken together, the data provided first evidence of the anticancer activity and possible molecular mechanism of PSN-A in prostate cancer. Further study is needed to develop PSN-A into a potential lead compound for the treatment of prostate cancer.

Pro-apoptotic effects of Kangfuxin on human stomach cancer cells and its underlying mechanism

Kangfuxin (KFX) is an oral liquid derived from Periplaneta americana, with complex components. KFX has been demonstrated to exhibit anticancer activity in a variety of different types of tumor, including gastric cancer; however, its underlying molecular mechanism remains unclear. The present study was designed to investigate the pro-apoptotic effects of KFX on SGC-7901 cells, in order to provide a theoretical basis for clinical application. In order to clarify the pro-apoptotic effects of KFX on SGC-7901 cells, MTT analysis was conducted. To evaluate the anticancer effect of KFX, peroxisome proliferator-activated receptor (PPAR)-γ was analyzed by reverse transcription-polymerase chain reaction. Western blot analysis was used to determine the effects of KFX on the expression of cleaved caspase-3, phosphorylated extracellular signal-regulated kinase (p-ERK), ERK, tumor protein p53 (p53), B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X, interleukin (IL)-6 and IL-1β. In addition, terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) analysis was used to detect apoptosis in SGC-7901 cells. It was revealed that PPAR-γ was increased in SGC-7901 cells following treatment with KFX, shown by an increase in mRNA expression. Furthermore, western blot analysis identified that KFX treatment groups exhibited markedly inhibited levels of Bcl-2, IL-6, IL-1β and p-ERK, and induced p53 protein expression. Additionally, TUNEL and MTT assays demonstrated that treatment with KFX may induce SGC-7901 cell apoptosis and inhibit proliferation. In conclusion, to the best of our knowledge, the results of the present study demonstrated for the first time that KFX may induce SGC-7901 cell apoptosis and inhibit its proliferation, and this may be primarily attributed to its role in mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase/ERK signaling pathway inhibition.