Physalin A induces G2/M phase cell cycle arrest in human non-small cell lung cancer cells: involvement of the p38 MAPK/ROS pathway

Two new sesquiterpenoid glycoside compounds from the calyces of Physalis alkekengi L. var. franchetii (Mast.) Makino

Two new sesquiterpenoid glycosides, 8α (H)-eudesmane-1,3,11 (13)-triene-2-one -12-O-β-D-glucopyranoside (1) and dmetelisproside B (2), together with ten known compounds (3-12) were isolated from calyces of Physalis alkekengi L. var. franchetii (Mast.) Makino (PAF). Their structures were unambiguously elucidated through HR-ESI-MS, UV, IR, and NMR spectral data. Compounds 1, 10, and 12 exhibited DPPH scavenging ability with IC50 values of 33.69 ± 6.65, 6.29 ± 0.06, and 25.66 ± 3.06 μM, respectively. Additionally, 10 and 12 demonstrated weak α-glucosidase inhibition activity with IC50 values of 250.9 ± 6.60 and 347.6 ± 2.48 μM, respectively.

Unveiling the potential of FOXO3 in lung cancer: From molecular insights to therapeutic prospects

Lung cancer poses a significant challenge regarding molecular heterogeneity, as it encompasses a wide range of molecular alterations and cancer-related pathways. Recent discoveries made it feasible to thoroughly investigate the molecular mechanisms underlying lung cancer, giving rise to the possibility of novel therapeutic strategies relying on molecularly targeted drugs. In this context, forkhead box O3 (FOXO3), a member of forkhead transcription factors, has emerged as a crucial protein commonly dysregulated in cancer cells. The regulation of the FOXO3 in reacting to external stimuli plays a key role in maintaining cellular homeostasis as a component of the molecular machinery that determines whether cells will survive or dies. Indeed, various extrinsic cues regulate FOXO3, affecting its subcellular location and transcriptional activity. These regulations are mediated by diverse signaling pathways, non-coding RNAs (ncRNAs), and protein interactions that eventually drive post-transcriptional modification of FOXO3. Nevertheless, while it is no doubt that FOXO3 is implicated in numerous aspects of lung cancer, it is unclear whether they act as tumor suppressors, promotors, or both based on the situation. However, FOXO3 serves as an intriguing possible target in lung cancer therapeutics while widely used anti-cancer chemo drugs can regulate it. In this review, we describe a summary of recent findings on molecular mechanisms of FOXO3 to clarify that targeting its activity might hold promise in lung cancer treatment.

Research progress on the chemical components and pharmacological effects of Physalis alkekengi L. var. franchetii (Mast.) Makino

Physalis Calyx seu Fructus is the dry calyx or the calyx with fruit of the Solanaceae plant Physalis alkekengi L. var. franchetii (Mast.) Makino, with a long history of use in medicine and food. However, despite its many potential therapeutic and culinary applications, P. alkekengi is not being exploited for these applications on a large scale. This study analysed various research related to the different chemical components of P. alkekengi, including steroids, flavonoids, alkaloids, phenylpropanoids, sucrose esters, piperazines, volatile oils, polysaccharides, amino acids, and trace elements. In addition, research related to the pharmacological activities of P. alkekengi, including its anti-inflammatory, anti microbial, antioxidative, hypoglycaemic, analgesic, anti-tumour, and immunomodulatory effects were investigated. Research articles from 1974 to 2023 were obtained from websites such as Google Scholar, Baidu Scholar, and China National Knowledge Infrastructure, and journal databases such as Scopus and PubMed, with the keywords such as Physalis alkekengi, components, effects, and activities. This study aims to provide a comprehensive understanding of the progress of phytochemical and pharmacological research on the phytochemical and pharmacological aspects of P. alkekengi and a reference for the better exploitation of P. alkekengi in the food and pharmaceutical industries.

An Update on Potential Molecular Biomarkers of Dietary Phytochemicals Targeting Lung Cancer Interception and Prevention

Since ancient times, dietary phytochemicals are known for their medicinal properties. They are broadly classified into polyphenols, terpenoids, alkaloids, phytosterols, and organosulfur compounds. Currently, there is considerable interest in their potential health effects against various diseases, including lung cancer. Lung cancer is the leading cause of cancer deaths with an average of five-year survival rate of lung cancer patients limited to just 14%. Identifying potential early molecular biomarkers of pre-malignant lung cancer cells may provide a strong basis to develop early cancer detection and interception methods. In this review, we will discuss molecular changes, including genetic alterations, inflammation, signal transduction pathways, redox imbalance, epigenetic and proteomic signatures associated with initiation and progression of lung carcinoma. We will also highlight molecular targets of phytochemicals during lung cancer development. These targets mainly consist of cellular signaling pathways, epigenetic regulators and metabolic reprogramming. With growing interest in natural products research, translation of these compounds into new cancer prevention approaches to medical care will be urgently needed. In this context, we will also discuss the overall pharmacokinetic challenges of phytochemicals in translating to humans. Lastly, we will discuss clinical trials of phytochemicals in lung cancer patients.

Advances in hyperbaric oxygen to promote immunotherapy through modulation of the tumor microenvironment

Hyperbaric oxygen therapy is a relatively safe treatment method that has been used for a long time in the clinic. It has been proven that it can enhance the sensitivity of radiotherapy and photodynamic therapy for cancer. However, there are few studies on hyperbaric oxygen and immunotherapy. In this article, we summarize that hyperbaric oxygen therapy regulates the tumor microenvironment through various pathways such as improving tumor hypoxia, targeting hypoxia-inducing factors, and generating reactive oxygen species. The change in the tumor microenvironment ultimately affects the curative effect of immunotherapy. Therefore, hyperbaric oxygen can influence immunotherapy by regulating the tumor microenvironment, providing a direction for the future development of immunotherapy.

Physalin A alleviates intervertebral disc degeneration via anti-inflammatory and anti-fibrotic effects

Background

The incidence of intervertebral disc degeneration (IVDD) is a common degenerative disease with inflammation, decreased autophagy, and progression of fibrosis as its possible pathogenesis. Physalin A (PA) is a widely studied anti-inflammatory drug. However, its therapeutic effects on IVDD remain unexplored. Therefore, we aimed to explore the therapeutic potential of PA in IVDD progression.

Materials and methods

In vivo, we investigated PA bioactivity using a puncture-induced IVDD rat model. IVDD signals and height changes were detected using X-ray, micro-CT, and MRI, and structural and molecular lesions using histological staining and immunohistochemistry of intervertebral disc sections. In vivo, interleukin-1 beta (IL-1β) and TGF-β1 were employed to establish inflammation fibrotic nucleus pulposus (NP) cells. The PA effect duration, concentration, influence pathways, and pathological changes in IVDD treatment were elucidated using western blotting, real-time PCR, and immunofluorescence.

Results

PA exerted significant effects on IVDD remission due to anti-inflammation, fibrosis reduction, and autophagy enhancement. In vitro, PA improved inflammation by blocking the NF-κB and MAPK pathways, whereas it promoted autophagy via the PI3K/AKT/mTOR pathway and affected fibrotic progression by regulating the SMAD2/3 pathway. Moreover, PA improved the disc degeneration process in IVDD model.

Conclusions

PA exhibited significant anti-inflammatory and anti-fibrotic effects and improved autophagy in vivo and in vitro IVDD models, thus effectively relieving IVDD progression, indicating it is a promising agent for IVDD treatment.

The translational potential of this article

This study successfully reveals that PA, a natural bioactive withanolide, effectively relieved IVDD progression via inflammation inhibition, fibrosis reduction, and autophagy enhancement, indicating it is a promising agent for IVDD treatment.

Implications of reactive oxygen species in lung cancer and exploiting it for therapeutic interventions

Lung cancer is the second (11.4%) most commonly diagnosed cancer and the first (18%) to cause cancer-related deaths worldwide. The incidence of lung cancer varies significantly among men, women, and high and low-middle-income countries. Air pollution, inhalable agents, and tobacco smoking are a few of the critical factors that determine lung cancer incidence and mortality worldwide. Reactive oxygen species are known factors of lung carcinogenesis resulting from the xenobiotics and their mechanistic paths are under critical investigation. Reactive oxygen species exhibit dual roles in cells, as a tumorigenic and anti-proliferative factor, depending on spatiotemporal context. During the precancerous state, ROS promotes cancer origination through oxidative stress and base-pair substitution mutations in pro-oncogenes and tumor suppressor genes. At later stages of tumor progression, they help the cancer cells in invasion, and metastases by activating the NF-kB and MAPK pathways. However, at advanced stages, when ROS exceeds the threshold, it promotes cell cycle arrest and induces apoptosis in cancer cells. ROS activates extrinsic apoptosis through death receptors and intrinsic apoptosis through mitochondrial pathways. Moreover, ROS upregulates the expression of beclin-1 which is a critical component to initiate autophagy, another form of programmed cell death. ROS is additionally involved in an intermediatory step in necroptosis, which catalyzes and accelerates this form of cell death. Various therapeutic interventions have been attempted to exploit this cytotoxic potential of ROS to treat different cancers. Growing body of evidence suggests that ROS is also associated with chemoresistance and cancer cell immunity. Considering the multiple roles of ROS, this review highlights the exploitation of ROS for various therapeutic interventions. However, there are still gaps in the literature on the dual roles of ROS and the involvement of ROS in cancer cell immunity and therapy resistance.

A Rapid and Sensitive LC−MS/MS Method for the Quantitation of Physalin A with Special Consideration to Chemical Stability in Rat Plasma: Application to a Pharmacokinetic Study

Physalin A is a promising natural product with excellent anti-inflammatory and anti-tumor activities. However, the pharmacokinetic profile of physalin A is still unclear. In this study, a rapid and sensitive analytical method based on LC–MS/MS for the quantitation of physalin A in rat plasma with special consideration to its chemical stability was developed and validated. To avoid the degradation of physalin A, the separation of plasma was conducted at 4 °C directly after the blood samples were collected. Meanwhile, plasma samples were immediately precipitated with acetonitrile containing tolbutamide (internal standard, IS) and the pH of the supernatant was adjusted to 1.5 with formic acid. Chromatographic separation of physalin A and IS was achieved on an ACQUITY UPLC BEH-C18 column (2.1 × 50 mm, 1.7 μm) using 0.1% formic acid and acetonitrile as mobile phase delivered at 0.3 mL/min in a gradient elution mode. Physalin A and IS were detected through negative ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions for physalin A and IS were m/z 525.1–148.9 and m/z 269.8–169.9, respectively. The developed method showed good linearity over the range of 2.00–400 ng/mL. This method was successfully applied to the pharmacokinetic study of physalin A in rats following its intragastric administration and the findings were beneficial for future studies of physalin A.

Therapeutic Applications of Physalins: Powerful Natural Weapons

Physalins, or 16,24-cyclo-13,14-seco steroids, are compounds belonging to the class of withanolides that can be found in plants of Solanaceae family, mainly in species belonging to the genus Physalis spp., which are annual herbaceous plants widely distributed in tropical and subtropical regions of the world. Physalins are versatile molecules that act in several cell signaling pathways and activate different mechanisms of cell death or immunomodulation. A number of studies have shown a variety of actions of these compounds, including anticancer, anti-inflammatory, antiparasitic, antimicrobial, antinociceptive, and antiviral activities. Here we reviewed the main findings related to the anticancer, immunomodulatory, and antiparasitic activities of physalins and its mechanisms of action, highlighting the \challenges and future directions in the pharmacological application of physalins.

Hidden in Plants-A Review of the Anticancer Potential of the Solanaceae Family in In Vitro and In Vivo Studies

Many of the anticancer agents that are currently in use demonstrate severe side effects and encounter increasing resistance from the target cancer cells. Thus, despite significant advances in cancer therapy in recent decades, there is still a need to discover and develop new, alternative anticancer agents. The plant kingdom contains a range of phytochemicals that play important roles in the prevention and treatment of many diseases. The Solanaceae family is widely used in the treatment of various diseases, including cancer, due to its bioactive ingredient content. The purpose of this literature review is to highlight the antitumour activity of Solanaceae extracts-single isolated compounds and nanoparticles with extracts-and their synergistic effect with chemotherapeutic agents in various in vitro and in vivo cancer models. In addition, the biological properties of many plants of the Solanaceae family have not yet been investigated, which represents a challenge and an opportunity for future anticancer therapy.

Oxidative Stress and AKT-Associated Angiogenesis in a Zebrafish Model and Its Potential Application for Withanolides

Oxidative stress and the AKT serine/threonine kinase (AKT) signaling pathway are essential regulators in cellular migration, metastasis, and angiogenesis. More than 300 withanolides were discovered from the plant family Solanaceae, exhibiting diverse functions. Notably, the relationship between oxidative stress, AKT signaling, and angiogenesis in withanolide treatments lacks comprehensive understanding. Here, we summarize connecting evidence related to oxidative stress, AKT signaling, and angiogenesis in the zebrafish model. A convenient vertebrate model monitored the in vivo effects of developmental and tumor xenograft angiogenesis using zebrafish embryos. The oxidative stress and AKT-signaling-modulating abilities of withanolides were highlighted in cancer treatments, which indicated that further assessments of their angiogenesis-modulating potential are necessary in the future. Moreover, targeting AKT for inhibiting AKT and its AKT signaling shows the potential for anti-migration and anti-angiogenesis purposes for future application to withanolides. This particularly holds for investigating the anti-angiogenetic effects mediated by the oxidative stress and AKT signaling pathways in withanolide-based cancer therapy in the future.

Natural Products from Physalis alkekengi L. var. franchetii (Mast.) Makino: A Review on Their Structural Analysis, Quality Control, Pharmacology, and Pharmacokinetics

The calyxes and fruits of Physalis alkekengi L. var. franchetii (Mast.) Makino (P. alkekengi), a medicinal and edible plant, are frequently used as heat-clearing and detoxifying agents in thousands of Chinese medicine prescriptions. For thousands of years in China, they have been widely used in clinical practice to treat throat disease, hepatitis, and bacillary dysentery. This systematic review summarizes their structural analysis, quality control, pharmacology, and pharmacokinetics. Furthermore, the possible development trends and perspectives for future research studies on this medicinal plant are discussed. Relevant information on the calyxes and fruits of P. alkekengi was collected from electronic databases, Chinese herbal classics, and Chinese Pharmacopoeia. Moreover, information was collected from ancient documents in China. The components isolated and identified in P. alkekengi include steroids, flavonoids, phenylpropanoids, alkaloids, nucleosides, terpenoids, megastigmane, aliphatic derivatives, organic acids, coumarins, and sucrose esters. Steroids, particularly physalins and flavonoids, are the major characteristic and bioactive ingredients in P. alkekengi. According to the literature, physalins are synthesized by the mevalonate and 2-C-methyl-d-erythritol-4-phosphate pathways, and flavonoids are synthesized by the phenylpropanoid pathway. Since the chemical components and pharmacological effects of P. alkekengi are complex and varied, there are different standards for the evaluation of its quality and efficacy. In most cases, the analysis was performed using high-performance liquid chromatography coupled with ultraviolet detection. A pharmacological study showed that the crude extracts and isolated compounds from P. alkekengi had extensive in vitro and in vivo biological activities (e.g., anti-inflammatory, anti-tumor, immunosuppressive, antibacterial, anti-leishmanial, anti-asthmatic, anti-diabetic, anti-oxidative, anti-malarial, anti-Alzheimer's disease, and vasodilatory). Moreover, the relevant anti-inflammatory and anti-tumor mechanisms were elucidated. The reported activities indicate the great pharmacological potential of P. alkekengi. Similarly, studies on the pharmacokinetics of specific compounds will also contribute to the progress of clinical research in this setting.

Assessing the Quality of Calyx of Physalis alkekengi L. var. franchetii Based on Quantitative Analysis of Q-Marker Combined with Chemometrics and Machine Learning Algorithms

Physalis alkekengi L. var. franchetii (PALF) is a traditional Chinese medicine, which is well known for its antimicrobial, anti-inflammatory, antipyretic, and expectorant properties. Its fruits and fruiting calyxes are used as dietary supplements and traditional herbs in China. However, the quality of calyxes is uneven, and it is prone to getting moldy or moth-eaten during storage. High-performance liquid chromatography (HPLC) fingerprints and multivariate chemometric methods were combined to evaluate quality, and three representative compounds were chosen as the quality markers (Q-markers). Hierarchical cluster analysis (HCA) and principal component analysis (PCA) provided a clear discrimination of PALF samples. Through further verification by partial least squares discriminant analysis (PLS-DA), backpropagation artificial neural network (BP-ANN), machine learning, and combination with the determination of the content, biology, and pharmacology effect judgment, galuteolin, rutin, and physalin O could be used as Q-markers that their contents affect the quality of PALF grade evaluation. A simple method was established to rapidly assess the quality of PALF that is important for its clinical application and storage and provide a reference for evaluating the quality of materials used in Chinese medicine.

Physalin A Inhibits MAPK and NF-κB Signal Transduction Through Integrin αVβ3 and Exerts Chondroprotective Effect

Osteoarthritis (OA) is a common articular ailment presented with cartilage loss and destruction that is common observed in the elderly population. Physalin A (PA), a natural bioactive withanolide, exerts anti-inflammatory residences in more than a few diseases; however, little is known about its efficacy for OA treatment. Here, we explored the therapeutic effects and potential mechanism of PA in mouse OA. After the in vitro administration of PA, the expression of inflammation indicators including inducible nitric oxide synthase and cyclooxygenase-2 was low, indicating that PA could alleviate the IL-1β-induced chondrocyte inflammation response. Moreover, PA reduced IL-1β-induced destruction of the extracellular matrix by upregulating the gene expression of anabolism factors, including collagen II, aggrecan, and sry-box transcription factor 9, and downregulating the gene expression of catabolic factors, including thrombospondin motif 5 and matrix metalloproteinases. In addition, the chondroprotective effect of PA was credited to the inhibition of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways. Furthermore, in vivo experiments showed that intra-articular injection of PA could alleviate cartilage destruction in a mouse OA model. However, the anti-inflammatory, anabolism enhancing, catabolism inhibiting, and MAPK and NF-κB signaling pathway inhibiting properties of PA on IL-1β-induced chondrocytes could be reversed when integrin αVβ3 is knocked down by siRNA. In conclusion, our work demonstrates that PA exhibits a chondroprotective effect that may be mediated by integrin αVβ3. Thus, PA or integrin αVβ3 might be a promising agent or molecular target for the treatment of OA.

Naturally occurring physalins from the genus Physalis: A review

Physalins, including physalins and neophysalins, are a class of highly oxygenated ergostane-type steroids. They are commonly known by the name of 16,24-cyclo-13,14-seco steroids, in which the disconnection of C-13 and C-14 produces an eight or nine-membered ring and the carbocyclization of C-16 and C-24 generates a new six-membered ring. Meanwhile, the oxidation of C-18 methyl to carboxyl group forms a 18,20-lactone, and the oxidation of C-14 and C-17 gets a heterocyclic oxygen acrossing rings C and D. Additionly, physalins frequently form an oxygen bridge to connect C-14 to C-27. Physalins are a kind of characteristic constituents from the species of the genus Physalis (Solanaceae), which are reported with a wide array of pharmacological activities, including anticancer, anti-inflammatory, immunoregulatory, antimicrobial, trypanocidal and leishmanicidal, antinociceptive, antidiabetic and some other activities. Herein,the research progress of physalins from the genus Physalis during the decade from 1970 to 2021 on phytochemistry, pharmacology, pharmacokinetics and application in China are systematically presented and discussed for the first time.

Physalin A, 13,14-Seco-16, 24-Cyclo-Steroid, Inhibits Stemness of Breast Cancer Cells by Regulation of Hedgehog Signaling Pathway and Yes-Associated Protein 1 (YAP1)

The Hedgehog (HH) signaling pathway plays an important role in embryonic development and adult organ homeostasis. Aberrant activity of the Hedgehog signaling pathway induces many developmental disorders and cancers. Recent studies have investigated the relationship of this pathway with various cancers. GPCR-like protein Smoothened (SMO) and the glioma-associated oncogene (GLI1) are the main effectors of Hedgehog signaling. Physalin A, a bioactive substance derived from Physalis alkekengi, inhibits proliferation and migration of breast cancer cells and mammospheres formation. Physalin A-induced apoptosis and growth inhibition of mammospheres, and reduced transcripts of cancer stem cell (CSC) marker genes. Physalin A reduced protein expressions of SMO and GLI1/2. Down-regulation of SMO and GLI1 using siRNA inhibited mammosphere formation. Physalin A reduced mammosphere formation by reducing GLI1 gene expression. Down-regulation of GLI1 reduced CSC marker genes. Physalin A reduced protein level of YAP1. Down-regulation of YAP1 using siRNA inhibited mammosphere formation. Physalin A reduced mammosphere formation through reduction of YAP1 gene expression. Down-regulation of YAP1 reduced CSC marker genes. We showed that treatment of MDA-MB-231 breast cancer cells with GLI1 siRNA induced inhibition of mammosphere formation and down-regulation of YAP1, a Hippo pathway effector. These results show that Hippo signaling is regulated by the Hedgehog signaling pathway. Physalin A also inhibits the canonical Hedgehog and Hippo signaling pathways, CSC-specific genes, and the formation of mammospheres. These findings suggest that physalin A is a potential therapeutic agent for targeting CSCs.

Dual Role of Reactive Oxygen Species and their Application in Cancer Therapy

Reactive oxygen species (ROS) play a dual role in the initiation, development, suppression, and treatment of cancer. Excess ROS can induce nuclear DNA, leading to cancer initiation. Not only that, but ROS also inhibit T cells and natural killer cells and promote the recruitment and M2 polarization of macrophages; consequently, cancer cells escape immune surveillance and immune defense. Furthermore, ROS promote tumor invasion and metastasis by triggering epithelial-mesenchymal transition in tumor cells. Interestingly, massive accumulation of ROS inhibits tumor growth in two ways: (1) by blocking cancer cell proliferation by suppressing the proliferation signaling pathway, cell cycle, and the biosynthesis of nucleotides and ATP and (2) by inducing cancer cell death via activating endoplasmic reticulum stress-, mitochondrial-, and P53- apoptotic pathways and the ferroptosis pathway. Unfortunately, cancer cells can adapt to ROS via a self-adaption system. This review highlighted the bidirectional regulation of ROS in cancer. The study further discussed the application of massively accumulated ROS in cancer treatment. Of note, the dual role of ROS in cancer and the self-adaptive ability of cancer cells should be taken into consideration for cancer prevention.

Physalin D attenuates hepatic stellate cell activation and liver fibrosis by blocking TGF-β/Smad and YAP signaling

BACKGROUND

Hepatic fibrosis is considered integral to the progression of chronic liver diseases, as it leads to the development of cirrhosis and hepatocellular carcinoma. The activation of hepatic stellate cells (HSCs) is the dominant event in hepatic fibrogenesis. The transforming growth factor-β1 (TGF-β1) and Yes-associated protein (YAP) pathways play a pivotal role in HSC activation, hepatic fibrosis and cirrhosis progression. Therefore, targeting the TGF-β/Smad and YAP signaling pathways is a promising strategy for antifibrotic therapy.

PURPOSE

The present study investigated the protective effects of Physalin D (PD), a withanolide isolated from Physalis species (Solanaceae), against liver fibrosis and further elucidated the mechanisms involved in vitro and in vivo.

STUDY DESIGN/METHODS

We conducted a series of experiments using carbon tetrachloride (CCl₄)- and bile duct ligation (BDL)-induced fibrotic mice and cultured LX-2 cells. Serum markers of liver injury, and the morphology, histology and fibrosis of liver tissue were investigated. Western blot assays and quantitative real-time PCR were used to investigate the mechanisms underlying the antifibrotic effects of PD.

RESULT

PD decreased TGF-β1-induced COL1A1 promoter activity. PD inhibited TGF-β1-induced expression of Collagen I and α-smooth muscle actin (α-SMA) in human hepatic stellate LX-2 cells. PD significantly ameliorated hepatic injury, including transaminase activities, histology, collagen deposition and α-SMA, in CCl₄- or BDL-induced mice. Moreover, PD markedly decreased the expression of phosphorylated Smad2/3 in vitro and in vivo. Furthermore, PD significantly decreased YAP protein levels, and YAP knockdown did not further enhance the effects of PD, namely α-SMA inhibition, Collagen I expression and YAP target gene expression in LX-2 cells.

CONCLUSION

These results clearly show that PD ameliorated experimental liver fibrosis by inhibiting the TGF-β/Smad and YAP signaling pathways, indicating that PD has the potential to effectively treat liver fibrosis.

Physalin B induces G2/M cell cycle arrest and apoptosis in A549 human non-small-cell lung cancer cells by altering mitochondrial function

Physalin B (PB) is one of the major constituents of Physalis alkekengi var. franchetii, a well-known Chinese traditional herb. In this study, we demonstrated for the first time that PB exhibits significant antiproliferative and apoptotic activity in A549 human lung cancer cells in a concentration-dependent and time-dependent manner. Flow cytometric analyses indicated that PB-induced G2/M arrest through down-regulation of cyclin B1 and cell division control protein cyclin-dependent kinase 1, and up-regulation of p21. The reduction in the level of cyclin B1/cyclin-dependent kinase 1 complex down-regulated oxidative phosphorylation multisubunit activity to reduce mitochondrial energetic homeostasis. Moreover, defects in mitochondrial ATP synthesis and mitochondrial membrane potential were found in PB-treated cell lines. These abnormalities led to an increase in intracellular superoxide and apoptosis. Thus, as an inhibitor of mitochondrial energetic homeostasis, PB demonstrates potent antitumor activities and may be developed as an alternative therapeutic agent against non-small-cell lung cancer.

Bioactive compounds induced in Physalis angulata L. by methyl-jasmonate: an investigation of compound accumulation patterns and biosynthesis-related candidate genes

We employed both metabolomic and transcriptomic approaches to explore the accumulation patterns of physalins, flavonoids and chlorogenic acid in Physalis angulata and revealed the genes associated with the biosynthesis of bioactive compounds under methyl-jasmonate (MeJA) treatment. Physalis angulata L. is an annual Solanaceae plant with a number of medicinally active compounds. Despite the potential pharmacological benefits of P. angulata, the scarce genomic information regarding this plant has limited the studies on the mechanisms of bioactive compound biosynthesis. To facilitate the basic understanding of the main chemical constituent biosynthesis pathways, we performed both metabolomic and transcriptomic approaches to reveal the genes associated with the biosynthesis of bioactive compounds under methyl-jasmonate (MeJA) treatment. Untargeted metabolome analysis showed that most physalins, flavonoids and chlorogenic acid were significantly upregulated. Targeted HPLC-MS/MS analysis confirmed variations in the contents of two important representative steroid derivatives (physalins B and G), total flavonoids, neochlorogenic acid, and chlorogenic acid between MeJA-treated plants and controls. Transcript levels of a few steroid biosynthesis-, flavonoid biosynthesis-, and chlorogenic acid biosynthesis-related genes were upregulated, providing a potential explanation for MeJA-induced active ingredient synthesis in P. angulata. Systematic correlation analysis identified a number of novel candidate genes associated with bioactive compound biosynthesis. These results may help to elucidate the regulatory mechanism underlying MeJA-induced active compound accumulation and provide several valuable candidate genes for further functional study.

Isolation and characterization of cytotoxic withanolides from the calyx of Physalis alkekengi L. var franchetii

Phytochemical investigation into the calyx of Physalis alkekengi L. var franchetii (Mast) Makino resulted in the isolation of ten cytotoxic withanolides, including five new withanolides, 1-5. Compounds 2-4 were obtained as epimeric withaphysalins. The new structures were elucidated by extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. The withanolides were evaluated for their cytotoxic activities against the A549 and K562 cell lines. Compounds 1 and 8 exhibited potent cytotoxic activity against both cell lines with IC₅₀ values of 1.9-4.3 μM and induced typical apoptosis as evaluated by flow cytometric analysis. Further studies indicated that 1 and 8 displayed antitumour effects by suppressing the PI3K-Akt-mTOR signalling pathway.

B7-H3 promotes the cell cycle-mediated chemoresistance of colorectal cancer cells by regulating CDC25A

Colorectal cancer (CRC) is one of the most common malignancies, and chemoresistance is one of the key obstacles in the clinical outcome. Here, we studied the function of B7-H3 in regulating cell cycle-mediated chemoresistance in CRC. The ability of B7-H3 in regulating chemoresistance was investigated via cell viability, clonogenicity, apoptosis and cycle analysis in vitro. Moreover, the role of B7-H3/CDC25A axis in regulating chemoresistance in vivo in the xenograft tumor models by intraperitoneal injection of oxaliplatin (L-OHP) and CDC25A inhibitors. The correlation between B7-H3 and CDC25A was examined in the CRC patients by immunohistochemistry (IHC) and pathological analyses. We found that B7-H3 could effectively enhance the resistance to a chemotherapeutic drug (oxaliplatin or 5-fluorouracil) via CDC25A. B7-H3 regulated the expression of CDC25A by the STAT3 signaling pathway in CRC cells. Furthermore, overexpression of B7-H3 enhanced chemoresistance by reducing the G2/M phase arrest in a CDC25A-dependent manner. Silencing CDC25A or treatment with CDC25A inhibitor could reverse the B7-H3-induced chemoresistance of cancer cells. Moreover, both B7-H3 and CDC25A were significantly upregulated in CRC samples compared with normal adjacent tissues and that the levels correlated with tumor stage. CDC25A was positively correlated with B7-H3 expression in this cohort. Taken together, our findings provide an alternative mechanism by which CRC cells can acquire chemoresistance via the B7-H3/CDC25A axis.

Piperlongumine Induces Cell Cycle Arrest via Reactive Oxygen Species Accumulation and IKKβ Suppression in Human Breast Cancer Cells

Piperlongumine (PL), a natural product derived from long pepper (Piper longum L.), is known to exhibit anticancer effects. However, the effect of PL on cell cycle-regulatory proteins in estrogen receptor (ER)-positive breast cancer cells is unclear. Therefore, we investigated whether PL can modulate the growth of ER-positive breast cancer cell line, MCF-7. We found that PL decreased MCF-7 cell proliferation and migration. Flow cytometric analysis demonstrated that PL induced G2/M phase cell cycle arrest. Moreover, PL significantly modulated the mRNA levels of cyclins B1 and D1, cyclin-dependent kinases 1, 4, and 6, and proliferating cell nuclear antigen. PL induced intracellular reactive oxygen species (hydrogen peroxide) accumulation and glutathione depletion. PL-mediated inhibition of IKKβ expression decreased nuclear translocation of NF-κB p65. Furthermore, PL significantly increased p21 mRNA levels. In conclusion, our data suggest that PL exerts anticancer effects in ER-positive breast cancer cells by inhibiting cell proliferation and migration via ROS accumulation and IKKβ suppression.

Apoptotic Pathway as the Therapeutic Target for Anticancer Traditional Chinese Medicines

Cancer is a leading cause of morbidity and mortality worldwide. Apoptosis is a process of programmed cell death and it plays a vital role in human development and tissue homeostasis. Mounting evidence indicates that apoptosis is closely related to the survival of cancer and it has emerged as a key target for the discovery and development of novel anticancer drugs. Various studies indicate that targeting the apoptotic signaling pathway by anticancer drugs is an important mechanism in cancer therapy. Therefore, numerous novel anticancer agents have been discovered and developed from traditional Chinese medicines (TCMs) by targeting the cellular apoptotic pathway of cancer cells and shown clinically beneficial effects in cancer therapy. This review aims to provide a comprehensive discussion for the role, pharmacology, related biology, and possible mechanism(s) of a number of important anticancer TCMs and their derivatives mainly targeting the cellular apoptotic pathway. It may have important clinical implications in cancer therapy.

Physalin A regulates the Nrf2 pathway through ERK and p38 for induction of detoxifying enzymes

Background

Physalin A isolated from Physalis alkekengi var. franchetii has been known to have many pharmacological properties. However, its effect through the Nrf2 pathway has not yet been elucidated. In the present study, we determined the effects of physalin A on cancer chemoprevention via the Nrf2 pathway.

Methods

Experiments were performed in Hepa-1c1c7 and HepG2 cells. The quinone reductase (QR) activity assay was used to assess the activity of physalin A and other compounds isolated from P. alkekengi. The antioxidant response element (ARE) reporter assay was used to determine physalin A induced transcription of Nrf2 target genes, whereas the oligonucleotide pull-down assay was used to investigate Nrf2 binding to the AREs post physalin A treatment. Real-time PCR and western blotting were performed to determine the expression of Nrf2 target genes. Immunocytochemistry was used to determine Nrf2 localization after treatment with physalin A. Kinase inhibitors were used to test the involvement of Nrf2-targeting kinases and the role of ERK and p38 phosphorylation was confirmed using western blotting.

Results

Physalin A significantly induced QR activity. As an upstream effector of QR, Nrf2 induced genes containing the ARE, which encode various antioxidants and detoxification enzymes. We observed that physalin A increased the expression of Nrf2 and its target genes in HepG2 cells. Moreover, we observed that physalin A-induced Nrf2 activation was regulated by ERK and p38 kinase in HepG2 cells.

Conclusions

Taken together, we showed that physalin A increased detoxifying enzyme expression via activation of Nrf2 and its target genes. These results imply that physalin A could be a potential chemopreventive agent for liver diseases, as well as cancer.

Neolignans from Red Raspberry ( Rubus idaeus L.) Exhibit Enantioselective Neuroprotective Effects against H2O2-Induced Oxidative Injury in SH-SY5Y Cells

Red raspberry has been well-known for its nutritional purpose. Although this fruit has been reported for its potent antioxidant activity and health-promoting properties, systematic studies responsible for the bioactive constituents were still insufficient. In the current study, three pairs of dihydrobenzofuran-type enantiomeric neolignans (1a/1b-3a/3b), including two new compounds (1b and 2a), were isolated from the fruit of Rubus idaeus. The structures of these enantiomers were determined through spectroscopic methods and quantum mechanical calculations. Biologically, enantiomers 2a and 2b exhibited significant enantioselective protective effects against H₂O₂-induced neurotoxicity at 50 μM (2a, 86.72 ± 1.17%; 2b, 69.70 ± 1.59%). The underlying mechanism study demonstrated that enantiomer 2a is able to attenuate H₂O₂-induced apoptosis, reactive oxygen species (ROS) generation, and mitochondrial dysfunction in SH-SY5Y cells. Overall, these findings provide a valuable foundation for the understanding of neuroprotective activities of red raspberry and further investigation on its potential application values.

Physalin D regulates macrophage M1/M2 polarization via the STAT1/6 pathway

The in vitro and in vivo effects of physalin D on macrophage M1/M2 polarization were investigated. In silico analysis was first performed for biological function prediction of different physalins. The results suggest physalins have similar predicted biological functions due to their similarities in chemical structures. The cytotoxicity of physalins was then analyzed based on cell apoptosis rate and cell viability evaluation. Physalin D was chosen for further study due to its minimal cytotoxicity. Bone marrow macrophages were isolated and induced with lipopolysaccharide/interferon (IFN)-γ for M1 polarization and interleukin (IL)-4/IL-13 for M2 polarization. The results showed that physalin D can repolarize M1 phenotype cells toward M2 phenotype. In addition, physalin D is protective in M2 macrophages to maintain the M2 phenotype in the presence of IFN-γ. On the molecular level, we found that physalin D suppressed the signal transducers and activators of transcription (STAT)1 activation and blocked STAT1 nuclear translocation. Conversely, physalin D can also activate STAT6 and enhance STAT6 nuclear translocation for M2 polarization. Taken together, these results suggested that physalin D regulates macrophage M1/M2 polarization via the STAT1/6 pathway.

Cellular senescence: Molecular mechanisms and pathogenicity

Cellular senescence is the arrest of normal cell division. Oncogenic genes and oxidative stress, which cause genomic DNA damage and generation of reactive oxygen species, lead to cellular senescence. The senescence-associated secretory phenotype is a distinct feature of senescence. Senescence is normally involved in the embryonic development. Senescent cells can communicate with immune cells to invoke an immune response. Senescence emerges during the aging process in several tissues and organs. In fact, increasing evidence shows that cellular senescence is implicated in aging-related diseases, such as nonalcoholic fatty liver disease, obesity and diabetes, pulmonary hypertension, and tumorigenesis. Cellular senescence can also be induced by microbial infection. During cellular senescence, several signaling pathways, including those of p53, nuclear factor-κB (NF-κB), mammalian target of rapamycin, and transforming growth factor-beta, play important roles. Accumulation of senescent cells can trigger chronic inflammation, which may contribute to the pathological changes in the elderly. Given the variety of deleterious effects caused by cellular senescence in humans, strategies have been proposed to control senescence. In this review, we will focus on recent studies to provide a brief introduction to cellular senescence, including associated signaling pathways and pathology.

Homoisoflavanone-1 isolated from Polygonatum odoratum arrests the cell cycle and induces apoptosis in A549 cells

Homoisoflavanone-1 is a natural compound that may be extracted from the Chinese medicinal herb Polygonatum odoratum, which has pronounced antioxidant activities. The present study reports that homoisoflavanone-1 significantly inhibited tumor cell growth and induced apoptosis in A549 non-small cell lung cancer (NSCLC) cells in a dose-dependent manner. Homoisoflavanone-1 arrested the cell cycle at the G2/M stage, which was associated with an increase in the accumulation of phosphorylated (p-)p38, p38, p53, and p-cyclin dependent kinase (Cdc)2 proteins, as well as a decrease in Cdc2 expression. In addition, treatment with homoisoflavanone-1 increased the levels of active caspase-3 and decreased Poly ADP-ribose polymerase, which was accompanied by a reduction in the B-cell lymphoma-2/Bak ratio and consequently, apoptosis. Furthermore, homoisoflavanone-1 increased the expression of endoplasmic reticulum (ER) stress-related proteins, including PERK, ATF4 and GADD34 in a dose-dependent manner. In conclusion, homoisoflavanone-1 induced apoptosis in A549 cells by regulating the mitochondria-caspase-dependent and ER stress pathways and resulted in G2/M arrest by activating the p38/p53 signaling pathway. These findings suggest that homoisoflavanone-1 extracted from Polygonatum odoratum may function as a cancer-suppressing agent and has potential as a novel therapeutic method against NSCLC.

Sinularin Selectively Kills Breast Cancer Cells Showing G2/M Arrest, Apoptosis, and Oxidative DNA Damage

The natural compound sinularin, isolated from marine soft corals, is antiproliferative against several cancers, but its possible selective killing effect has rarely been investigated. This study investigates the selective killing potential and mechanisms of sinularin-treated breast cancer cells. In 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H- tetrazolium, inner salt (MTS) assay, sinularin dose-responsively decreased the cell viability of two breast cancer (SKBR3 and MDA-MB-231) cells, but showed less effect on breast normal (M10) cells after a 24 h treatment. According to 7-aminoactinomycin D (7AAD) flow cytometry, sinularin dose-responsively induced the G2/M cycle arrest of SKBR3 cells. Sinularin dose-responsively induced apoptosis on SKBR3 cells in terms of a flow cytometry-based annexin V/7AAD assay and pancaspase activity, as well as Western blotting for cleaved forms of poly(ADP-ribose) polymerase (PARP), caspases 3, 8, and 9. These caspases and PARP activations were suppressed by N-acetylcysteine (NAC) pretreatment. Moreover, sinularin dose-responsively induced oxidative stress and DNA damage according to flow cytometry analyses of reactive oxygen species (ROS), mitochondrial membrane potential (MitoMP), mitochondrial superoxide, and 8-oxo-2'-deoxyguanosine (8-oxodG)). In conclusion, sinularin induces selective killing, G2/M arrest, apoptosis, and oxidative DNA damage of breast cancer cells.

#2714, a novel active inhibitor with potent G2/M phase arrest and antitumor efficacy in preclinical models

Arresting cell cycle has been one of the most common approaches worldwide in cancer therapy. Specifically, arresting cells in the G2/M phase is a promising therapeutic approach in the battle against lung cancer. In the present study, we demonstrated the anticancer activities and possible mechanism of compound #2714, which can prompt G2/M phase arrest followed by cell apoptosis induction in Lewis lung carcinoma LL/2 cells. In vitro, #2714 significantly inhibited LL/2 cell viability in a concentration- and time-dependent manner while exhibiting few toxicities on non-cancer cells. The mechanism study showed that cell proliferation inhibition due to the treatment with #2714 correlated with G2/M phase arrest and was followed by LL/2 cell apoptosis. The characterized changes were associated with the downregulation of phosphorylated cell division cycle 25C (Cdc25C) and upregulation of p53. Apoptosis-associated activation of cleaved caspase-3 was also detected. Moreover, #2714 strongly attenuated LL/2 cell proliferation by disrupting the phosphorylation of p44/42 mitogen-activated protein kinase (MAPK). In vivo, intraperitoneal administration of #2714 (25–100 mg/kg/day) to mice bearing established tumors in xenograft models significantly prevented LL/2 tumor growth (58.1%) without detectable toxicity. Compound #2714 significantly increased apoptosis in LL/2 lung cancer cells in mice models, as observed via terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay, and the data from an immunohistochemical analysis showed that #2714 remarkably inhibited the proliferation and angiogenesis of lung cancer in vivo. Taken together, our data suggest that #2714 has a high potential anti-lung cancer efficacy with a pathway-specific mechanism of G2/M phase arrest and subsequent apoptosis induction both in vitro and in vivo; its potential to be an anticancer candidate warrants further investigation.

Physalis alkekengi L. var. franchetii (Mast.) Makino: An ethnomedical, phytochemical and pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

The calyxes and fruits of Physalis alkekengi L. var. franchetii (Mast.) Makino (Physalis Calyx seu Fructus), have been widely used in traditional and indigenous Chinese medicines for the therapy of cough, excessive phlegm, pharyngitis, sore throat, dysuria, pemphigus, eczema, and jaundice with a long history.

AIM OF THE REVIEW

The present review aims to achieve a comprehensive and up-to-date investigation in ethnomedical uses, phytochemistry, pharmacology, and toxicity of P. alkekengi var. franchetii, particularly its calyxes and fruits. Through analysis of these findings, evidences supporting their applications in ethnomedicines are illustrated. Possible perspectives and opportunities for the future research are analyzed to highlight the gaps in our knowledge that deserves further investigation.

MATERIAL AND METHODS

Information on P. alkekengi var. franchetii was collected via electronic search of major scientific databases (e.g. Web of Science, SciFinder, Google Scholar, Pubmed, Elsevier, SpringerLink, Wiley online and China Knowledge Resource Integrated) for publications on this medicinal plant. Information was also obtained from local classic herbal literature on ethnopharmacology.

RESULTS

About 124 chemical ingredients have been characterized from different parts of this plant. Steroids (particularly physalins) and flavonoids are the major characteristic and bioactive constituents. The crude extracts and the isolated compounds have demonstrated various in vitro and in vivo pharmacological functions, such as anti-inflammation, inhibition of tumor cell proliferation, antimicrobial activity, diuretic effect, anti-diabetes, anti-asthma, immunomodulation, and anti-oxidation.

CONCLUSIONS

P. alkekengi var. franchetii is an important medicinal plant for the ethnomedical therapy of microbial infection, inflammation, and respiratory diseases (e.g. cough, excessive phlegm, pharyngitis). Phytochemical and pharmacological investigations of this plant definitely increased in the past half century. The chemical profiles, including ingredients and structures, have been adequately verified. Modern pharmacological studies supported its uses in the traditional and folk medicines, however, the molecular mechanisms of purified compounds remained unclear and were worth of further exploration. Therefore, the researchers should be paid more attention to a better utilization of this plant.

Neuroprotective Effects of 1,2-Diarylpropane Type Phenylpropanoid Enantiomers from Red Raspberry against H2O2-Induced Oxidative Stress in Human Neuroblastoma SH-SY5Y Cells

Red raspberry (Rubus idaeus L.) is an edible fruit-producing species belonging to the Rosaceae family. In our search for the health-promoting constituents from this fruit, four pairs of enantiomeric phenylpropanoids (1a/1b-4a/4b), including three new compounds (1a and 2a/2b), were isolated from red raspberry. Their structures were elucidated by a combination of the extensive NMR spectroscopic data analyses, high-resolution electrospray ionization mass spectrometry and comparison between the experimental measurements of electronic circular dichroism (ECD) and calculated ECD spectra by time-dependent density functional theory (TDDFT). In addition, their neuroprotective effects against H₂O₂-induced oxidative stress in human neuroblastoma SH-SY5Y cells were investigated, and the results showed enantioselectivity, in which that 3a exhibited noticeable neuroprotective activity, while its enatiomer 3b exhibited no obvious protective effect. Further study demonstrated that 3a could selectively inhibit the apoptosis induction and reactive oxygen species (ROS) accumulation by enhancing the activity of catalase (CAT) in H₂O₂-treated human neuroblastoma SH-SY5Y cells. These findings shed much light on a better understanding of the neuroprotective effects of these enantiomers and provide new insights into developing better treatment of neurodegenerative diseases in the future.

Actein induces autophagy and apoptosis in human bladder cancer by potentiating ROS/JNK and inhibiting AKT pathways

Human bladder cancer is a common genitourinary malignant cancer worldwide. However, new therapeutic strategies are required to overcome its stagnated survival rate. Triterpene glycoside Actein (ACT), extracted from the herb black cohosh, suppresses the growth of human breast cancer cells. Our study attempted to explore the role of ACT in human bladder cancer cell growth and to reveal the underlying molecular mechanisms. We found that ACT significantly impeded the bladder cancer cell proliferation via induction of G2/M cycle arrest. Additionally, ACT administration triggered autophagy and apoptosis in bladder cancer cells, proved by the autophagosome formation, LC3B-II accumulation, improved cleavage of Caspases/poly (ADP-ribose) polymerase (PARP). Furthermore, reduction of reactive oxygen species (ROS) and p-c-Jun N-terminal kinase (JNK) could markedly reverse ACT-induced autophagy and apoptosis. In contrast, AKT and mammalian target of rapamycin (mTOR) were greatly de-phosphorylated by ACT, while suppressing AKT and mTOR activity could enhance the effects of ACT on apoptosis and autophagy induction. In vivo, ACT reduced the tumor growth with little toxicity. Taken together, our findings indicated that ACT suppressed cell proliferation, induced autophagy and apoptosis through promoting ROS/JNK activation, and blunting AKT pathway in human bladder cancer, which indicated that ACT might be an effective candidate against human bladder cancer in future.

Sinularin induces oxidative stress-mediated G2/M arrest and apoptosis in oral cancer cells

Soft corals-derived natural product, sinularin, was antiproliferative against some cancers but its effect and detailed mechanism on oral cancer cells remain unclear. The subject of this study is to examine the antioral cancer effects and underlying detailed mechanisms in terms of cell viability, oxidative stress, cell cycle analysis, and apoptosis analyses. In MTS assay, sinularin dose-responsively decreased cell viability of three oral cancer cells (Ca9-22, HSC-3, and CAL 27) but only little damage to oral normal cells (HGF-1). This cell killing effect was rescued by the antioxidant N-acetylcysteine (NAC) pretreatment. Abnormal cell morphology and induction of reactive oxygen species (ROS) were found in sinularin-treated oral cancer Ca9-22 cells, however, NAC pretreatment also recovered these changes. Sinularin arrested the Ca9-22 cells at G2/M phase and dysregulated the G2/M regulatory proteins such as cdc2 and cyclin B1. Sinularin dose-responsively induced apoptosis on Ca9-22 cells in terms of flow cytometry (annexin V and pancaspase analyses) and western blotting (caspases 3, 8, 9) and poly (ADP-ribose) polymerase (PARP). These apoptotic changes of sinularin-treated Ca9-22 cells were rescued by NAC pretreatment. Taken together, sinularin induces oxidative stress-mediated antiproliferation, G2/M arrest, and apoptosis against oral cancer cells and may be a potential marine drug for antioral cancer therapy.

Anti-proliferation of triple-negative breast cancer cells with physagulide P: ROS/JNK signaling pathway induces apoptosis and autophagic cell death

Physagulide P (PP), a new natural compound, was isolated from Physalis angulate L. in our laboratory. In this study, we demonstrated that PP potently suppressed cell proliferation by inducing G2/M phase arrest in MDA-MB-231 and MDA-MB-468 cells. Moreover, PP provoked apoptosis by decreasing the mitochondrial membrane potential and elevating the Bax/Bcl-2 protein expression ratio. The caspase inhibitor Z-VAD-FMK partly restore cell viability, suggesting that apoptosis plays as an important role in the anti-proliferative effect of PP. PP-treated cells also underwent autophagy, as evidenced by the formation of autophagosomes and the accumulation of LC3BII. Furthermore, the knockdown of LC3B reduced PP-induced cytotoxicity, indicating that autophagy played an anticancer effect. PP also induced the generation of reactive oxygen species (ROS) and resulted in c-Jun N-terminal kinases (JNK) activation. Accordingly, JNK siRNA significantly attenuated PP-triggered apoptosis and autophagy, and ROS scavengers almost completely reverse this apoptosis and autophagy. The ROS scavenger also blocked PP-induced G2/M phase arrest and the phosphorylation of JNK. Our results revealed that PP induced G2/M phase arrest, apoptosis and autophagy via the ROS/JNK signaling pathway in MDA-MB-231 and MDA-MB-468 cells. Therefore, PP is a promising candidate for the development of antitumor drugs for the treatment of triple-negative breast cancer.

2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid, a glutathione reductase inhibitor, induces G2/M cell cycle arrest through generation of thiol oxidative stress in human esophageal cancer cells

Esophageal squamous cell carcinoma (ESCC) is a highly malignant cancer with poor response to both of chemotherapy and radiotherapy. 2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid (2-AAPA), an irreversible inhibitor of glutathione reductase (GR), is able to induce intracellular oxidative stress, and has shown anticancer activity in many cancer cell lines. In this study, we investigated the effects of 2-AAPA on the cell proliferation, cell cycle and apoptosis and aimed to explore its mechanism of action in human esophageal cancer TE-13 cells. It was found that 2-AAPA inhibited growth of ESCC cells in a dose-dependent manner and it did not deplete reduced glutathione (GSH), but significantly increased the oxidized form glutathione (GSSG), resulting in decreased GSH/GSSG ratio. In consequence, significant reactive oxygen species (ROS) production was observed. The flow cytometric analysis revealed that 2-AAPA inhibited growth of esophageal cancer cells through arresting cell cycle in G₂/M phase, but apoptosis-independent mechanism. The G₂/M arrest was partially contributed by down-regulation of protein expression of Cdc-25c and up-regulation of phosphorylated Cdc-2 (Tyr15), Cyclin B1 (Ser147) and p53. Meanwhile, 2-AAPA-induced thiol oxidative stress led to increased protein S-glutathionylation, which resulted in α-tubulin S-glutathionylation-dependent depolymerization of microtubule in the TE-13 cells. In conclusion, we identified that 2-AAPA as an effective thiol oxidative stress inducer and proliferation of TE-13 cells were suppressed by G₂/M phase cell cycle arrest, mainly, through α-tubulin S-glutathionylation-mediated microtubule depolymerization. Our results may introduce new target and approach for esophageal cancer therapy through generation of GR-mediated thiol oxidative stress.

Chrysin induces death of prostate cancer cells by inducing ROS and ER stress

Chrysin is a natural flavone found in numerous plant extracts, honey, and propolis that has multiple biological activities including anti-cancer effects. Understanding of biological mechanisms mediated in response to chrysin in cancerous cells may provide novel insight into chemotherapeutic approaches with reduced side effects in cancers. In the present study, we investigated functional roles of chrysin in progression of prostate cancer cells using DU145 and PC-3 cell lines. The results showed that chrysin induced apoptosis of cells evidenced by DNA fragmentation and increasing the population of both DU145 and PC-3 cells in the sub-G₁ phase of the cell cycle. In addition, chrysin reduced expression of proliferating cell nuclear antigen in the prostate cancer cell lines compared to untreated prostate cancer cells. Moreover, chrysin induced loss of mitochondria membrane potential (MMP), while increasing production of reactive oxygen species (ROS) and lipid peroxidation in a dose-dependent manner. Also, it induced endoplasmic reticulum (ER) stress through activation of unfolded protein response (UPR) proteins including PRKR-like ER kinase (PERK), eukaryotic translation initiation factor 2α (eIF2α), and 78 kDa glucose-regulated protein (GRP78) in DU145 and PC-3 cells. The chrysin-mediated intracellular signaling pathways suppressed phosphoinositide 3-kinase (PI3K) and the abundance of AKT, P70S6K, S6, and P90RSK proteins, but stimulated mitogen-activated protein kinases (MAPK) and activation of ERK1/2 and P38 proteins in the prostate cancer cells. Collectively, these results indicate that chrysin initiates cell death through induction of mitochondrial-mediated apoptosis and ER stress, and regulation of signaling pathways responsible for proliferation of prostate cancer cells.

Importance of ROS-mediated autophagy in determining apoptotic cell death induced by physapubescin B

Physapubescin B, a steroidal compound extracted from the plant Physalis pubescens L. (Solanaceae), has been reported to possess anti-cancer potential, whereas the molecular mechanism remains elusive. In this study, we first demonstrated that physapubescin B induced autophagy in human cancer cells based on the evidence that physapubescin B increased lipidation of microtubule-associated protein 1 light chain 3 (LC3) as well as number of GFP-LC3 puncta. We further examined the molecular mechanisms and found that physapubescin B enhanced the autophagic flux through promotion of reactive oxygen species (ROS)-mediated suppression of mammalian target of rapamycin complex I (mTORC1), the key negative regulator of autophagy. Additionally, excessive ROS caused by physapubescin B also induced p53-dependent apoptotic cell death. Furthermore, we provided evidence that inhibition of autophagy either by a chemical inhibitor or gene silencing promoted physapubescin B-induced apoptotic cell death, indicating that autophagy serves as a cell survival mechanism to protect cell death. Thus, our data provide a clue that inhibition of autophagy would serve as a novel strategy for enhancing the anti-cancer potential of physapubescin B.

Flavans with cytotoxic activity from the stem and root bark of Daphne giraldii

Thirteen new flavan compounds named daphnegiravans A–M (1–13) and eight known analogues (14–21) were isolated from the stem and root bark of Daphne giraldii. Further cytotoxicity investigation was conducted on 3 and 9–12.