Targeting caspases in cancer therapeutics

Ultrastructural, molecular and haemato-immunological changes: Multifaceted toxicological effects of microcystin-LR in rohu, Labeo rohita

No water body is resilient to afflicts of algal bloom, if goes unmanaged. With the increasing trend of intensification, eutrophication and climate change, Labeo rohita (rohu) is highly anticipated to suffer from the deleterious effects of bloom and eventually its toxins. A comprehensive study was conducted to understand the toxicopathological effects of microcystin-LR (MC-LR) in rohu following intraperitoneal injection of 96 h-LD50 dose i.e., 713 μg kg-1. Substantial changes in micro- and ultrastructural level were evident in histopathology and transmission electron microscope (TEM) study. The haematological, biochemical, cellular and humoral innate immune biomarkers were significantly altered (p < 0.05) in MC-LR treated fish. The mRNA transcript levels of IL-1β, IL-10, IgM and IgZ in liver and kidney tissues were significantly up-regulated in 12 hpi and declined in 96 hpi MC-LR exposed fish. The relative mRNA expression of caspase 9 in the liver and kidney indicates mitochondrial-mediated apoptosis which was strongly supported by TEM study. In a nutshell, our study illustrates for the first time MC-LR induced toxicological implications in rohu displaying immunosuppression, enhanced oxidative stress, pathophysiology, modulation in mRNA transcription, genotoxicity, structural and ultrastructural alterations signifying it as a vulnerable species for MC-LR intoxication.

A Comprehensive Exploration of Caspase Detection Methods: From Classical Approaches to Cutting-Edge Innovations

The activation of caspases is a crucial event and an indicator of programmed cell death, also known as apoptosis. These enzymes play a central role in cancer biology and are considered one promising target for current and future advancements in therapeutic interventions. Traditional methods of measuring caspase activity such as antibody-based methods provide fundamental insights into their biological functions, and are considered essential tools in the fields of cell and cancer biology, pharmacology and toxicology, and drug discovery. However, traditional methods, though extensively used, are now recognized as having various shortcomings. In addition, these methods fall short of providing solutions to and matching the needs of the rapid and expansive progress achieved in studying caspases. For these reasons, there has been a continuous improvement in detection methods for caspases and the network of pathways involved in their activation and downstream signaling. Over the past decade, newer methods based on cutting-edge state-of-the-art technologies have been introduced to the biomedical community. These methods enable both the temporal and spatial monitoring of the activity of caspases and their downstream substrates, and with enhanced accuracy and precision. These include fluorescent-labeled inhibitors (FLIs) for live imaging, single-cell live imaging, fluorescence resonance energy transfer (FRET) sensors, and activatable multifunctional probes for in vivo imaging. Recently, the recruitment of mass spectrometry (MS) techniques in the investigation of these enzymes expanded the repertoire of tools available for the identification and quantification of caspase substrates, cleavage products, and post-translational modifications in addition to unveiling the complex regulatory networks implicated. Collectively, these methods are enabling researchers to unravel much of the complex cellular processes involved in apoptosis, and are helping generate a clearer and comprehensive understanding of caspase-mediated proteolysis during apoptosis. Herein, we provide a comprehensive review of various assays and detection methods as they have evolved over the years, so to encourage further exploration of these enzymes, which should have direct implications for the advancement of therapeutics for cancer and other diseases.

Decoding cell death signalling: Impact on the response of breast cancer cells to approved therapies

Breast cancer is a principal cause of cancer-related mortality in female worldwide. While many approved therapies have shown promising outcomes in treating breast cancer, understanding the intricate signalling pathways controlling cell death is crucial for optimizing the treatment outcome. A growing body of evidence has unveiled the aberrations in multiple cell death pathways across diverse cancer types, highlighting these pathways as appealing targets for therapeutic interventions. In this review, we provide a comprehensive overview of the current state of knowledge on the cell death signalling mechanisms with a particular focus on their impact on the response of breast cancer cells to approved therapies. Additionally, we discuss the potentials of combination therapies that exploit the synergy between approved drugs and therapeutic agents targeting modulators of cell death pathways.

The adverse effect of anticancer drug toremifene on vascular smooth muscle cells is an important aspect of its tumor growth inhibition

PURPOSE

Toremifene (TOR) is widely used as an antineoplastic drug and has an inhibitory effect on angiogenesis in mesenteric desmoid tumors and vascular intracranial solitary fibrous tumors. However, no study has investigated the direct effect of TOR on vascular cells. This study aimed at exploring the effect of TOR on the behaviors of vascular smooth muscle cells (VSMCs).

METHODS

Human aortic umbilical vascular smooth muscle cells (HAVSMCs) were treated by TOR. Cell morphology, migration, adhesion, and proliferation assay were investigated. The cell cycle, apoptosis, mitochondrial membrane potential, and reactive oxygen species were assessed using flow cytometry. Caspase-3 and 9 activities were assayed using Caspase-3 and Caspase-9 Activity Assay kits, respectively. Immunofluorescence and Western blot assays were carried out to characterize protein expressions of PCNA, p53, and Rho/ROCK signaling pathway.

RESULTS

TOR damaged cytoskeleton, inhibited VSMC proliferation, migration, and adhesion, and induced abnormal cell morphology and apoptosis. The antiproliferative activity of TOR was associated with the induction of G0/G1 phase arrest, blocking the cell cycle. TOR disrupted intracellular reactive oxygen species and mitochondrial membrane potential, and enhanced p53 expression and the activities of caspase-3 and caspase-9. Thus, TOR-induced apoptosis by the mitochondrial signaling pathway. Additionally, TOR induced decreased Rho, ROCK, MLC, and pMLC proteins. Collectively, TOR may affect multiple behaviors of VSMCs by damaging cytoskeleton through the Rho/ROCK pathway.

CONCLUSION

The adverse effect of TOR on VSMCs could be considered as an important aspect of tumor growth inhibition.

Sedum middendorffianum Maxim Induces Apoptosis and Inhibits the Invasion of Human Ovarian Cancer Cells via Oxidative Stress Regulation

Sedum middendorffianum Maxim (SMM) is a Korean endemic plant belonging to the Crassulaceae family. This study aimed to investigate the antitumor effects of the SMM extract on human ovarian cancer cells. Among five endemic plants grown in Korea, the SMM extract showed the most potent cytotoxicity in ovarian cancer cells and had little effect on normal ovarian surface epithelial cells. Furthermore, we revealed that the SMM extract dose-dependently induced apoptosis in human ovarian cancer A2780 and SKOV3 cells. The SMM extract markedly stimulated the activation of caspase-3/8, while the broad-spectrum caspase inhibitor and caspase-8 selective inhibitor significantly reversed SMM extract-induced apoptosis. In addition, the SMM extract significantly inhibited cell invasion and the expression levels of matrix metalloproteinase (MMP)-2 and MMP-9 in ovarian cancer cells. Notably, the SMM extract increased the generation of intracellular ROS, and pretreatment with antioxidant N-acetyl-L-cysteine (NAC) significantly suppressed SMM-induced cytotoxicity and anti-invasive activity. Moreover, NAC treatment reversed the SMM-induced inhibition of MMP-2/9 expression. Taken together, these data suggest that the SMM extract induces caspase-dependent apoptotic cell death and inhibits MMP-dependent invasion via ROS regulation.

Co-Delivery System of Curcumin and Colchicine Using Functionalized Mesoporous Silica Nanoparticles Promotes Anticancer and Apoptosis Effects

Purpose: Many natural agents have a high anticancer potential, and their combination may be advantageous for improved anticancer effects. Such agents, however, often are not water soluble and do not efficiently target cancer cells, and the kinetics of their action is poorly controlled. One way to overcome these barriers is to combine natural agents with nanoparticles. Our aim in the current study was to fabricate an anticancer nanoformulation for co-delivery of two natural agents, curcumin (CR) and colchicine (CL), with a core-shell structure. Using cancer cell lines, we compared the anticancer efficacy between the combination and a nanoformulation with CL alone. Methods: For the single-drug nanoformulation, we used phosphonate groups to functionalize mesoporous silica nanoparticles (MSNs) and loaded the MSNs with CL. Additional loading of this nanoformulation with CR achieved the co-delivery format. To create the structure with a core shell, we selected a chitosan−cellulose mixture conjugated with targeting ligands of folic acid for the coating. For evaluating anticancer and apoptosis effects, we assessed changes in important genes and proteins in apoptosis (p53, caspase-3, Bax, Bcl-2) in several cell lines (MCF-7, breast adenocarcinoma; HCT-116, colon carcinoma; HOS, human osteosarcoma; and A-549, non−small cell lung cancer). Results: Nanoformulations were successfully synthesized and contained 10.9 wt.% for the CL single-delivery version and 18.1 wt.% for the CL+CR co-delivery nanoformulation. Anticancer effects depended on treatment, cell line, and concentration. Co-delivery nanoformulations exerted anticancer effects that were significantly superior to those of single delivery or free CL or CR. Anticancer effects by cell line were in the order of HCT-116 > A549 > HOS > MCF-7. The lowest IC50 value was obtained for the nanoformulation consisting of CL and CR coated with a polymeric shell conjugated with FA (equivalent to 4.1 ± 0.05 µg/mL). With dual delivery compared with the free agents, we detected strongly increased p53, caspase-3, and Bax expression, but inhibition of Bcl-2, suggesting promotion of apoptosis. Conclusions: Our findings, although preliminary, indicate that the proposed dual delivery nanoformulation consisting of nanocore: MSNs loaded with CL and CR and coated with a shell of chitosan−cellulose conjugated folic acid exerted strong anticancer and apoptotic effects with potent antitumor activity against HCT-116 colon cells. The effect bested CL alone. Evaluating and confirming the efficacy of co-delivery nanoformulations will require in vivo studies.

Arctigenin induces caspase-dependent apoptosis in FaDu human pharyngeal carcinoma cells

The present study was carried out to investigate the effect of Arctigenin on cell growth and the mechanism of cell death elicited by Arctigenin were examined in FaDu human pharyngeal carcinoma cells. To determine the apoptotic activity of Arctigenin in FaDu human pharyngeal carcinoma cells, cell viability assay, DAPI staining, caspase activation analysis, and immunoblotting were performed. Arctigenin inhibited the growth of cells in a dose-dependent manner and induced nuclear condensation and fragmentation. Arctigenin-treated cells showed caspase-3/7 activation and increased apoptosis versus control cells. FasL, a death ligand associated with extrinsic apoptotic signaling pathways, was up-regulated by Arctigenin treatment. Moreover, caspase-8, a part of the extrinsic apoptotic pathway, was activated by Arctigenin treatments. Expressions of anti-apoptotic factors such as Bcl-2 and Bcl-xL, components of the mitochondria-dependent intrinsic apoptosis pathway, significantly decreased following Arctigenin treatment. The expressions of pro-apoptotic factors such as BAX, BAD and caspase-9, and tumor suppressor -53 increased by Arctigenin treatments. In addition, Arctigenin activated caspase-3 and poly (ADP-ribose) polymerase (PARP) induced cell death. Arctigenin also inhibited the proliferation of FaDu cells by the suppression of p38, NF-κB, and Akt signaling pathways. These results suggest that Arctigenin may inhibit cell proliferation and induce apoptotic cell death in FaDu human pharyngeal carcinoma cells through both the mitochondria-mediated intrinsic pathway and the death receptor-mediated extrinsic pathway.

A comprehensive review of flaxseed (Linum usitatissimum L.): health-affecting compounds, mechanism of toxicity, detoxification, anticancer and potential risk

Flaxseed consumption (Linum usitatissimum L.) has increased due to its potential health benefits, such as protection against inflammation, diabetes, cancer, and cardiovascular diseases. However, flaxseeds also contains various anti-nutritive and toxic compounds such as cyanogenic glycosides, and phytic acids etc. In this case, the long-term consumption of flaxseed may pose health risks due to these non-nutritional substances, which may be life threatening if consumed in high doses, although if appropriately utilized these may prevent/treat various diseases by preventing/inhibiting and or reversing the toxicity induced by other compounds. Therefore, it is necessary to remove or suppress the harmful and anti-nutritive effects of flaxseeds before these are utilized for large-scale as food for human consumption. Interestingly, the toxic compounds of flaxseed also undergoes biochemical detoxification in the body, transforming into less toxic or inactive forms like α-ketoglutarate cyanohydrin etc. However, such detoxification is also a challenge for the development, scalability, and real-time quantification of these bioactive substances. This review focuses on the health affecting composition of flaxseed, along with health benefits and potential toxicity of its components, detoxification methods and mechanisms with evidence supported by animal and human studies.

Anti-inflammatory and intestinal microbiota modulation properties of high hydrostatic pressure treated cyanidin-3-glucoside and blueberry pectin complexes on dextran sodium sulfate-induced ulcerative colitis mice

This study investigated the anti-inflammatory effects of cyanidin-3-glucoside (C3G) and blueberry pectin (BP) complexes on mice with dextran sodium sulfate (DSS)-induced colitis before and after high hydrostatic pressure (HHP) treatment. Real-time polymerase chain reaction (RT-PCR), western blotting, and 16S rDNA sequencing were used to study the expression of inflammation-related factors, activation of signal pathway-related proteins, and changes in the intestinal flora in ulcerative colitis (UC) mice. The results showed that HHP-treated C3G-BP complexes significantly relieved diarrhea and blood loss in the stool of UC mice and alleviated colon shortening. The potential mechanism of action involved reduction in intestinal oxidative stress mRNA expression of pro-inflammatory factors, improvement in anti-inflammatory factor levels, inhibition of the NF-κB signaling pathway, increased protein levels of Bcl-2/Bax and caspase-3/cleaved caspase-3 genes, and improved gut microbiota composition. Compared with other experimental groups, the HHP-treated C3G-BP complexes group exhibited the best anti-inflammatory effect on DSS-induced UC mice. The results may provide new ideas for using C3G-BP complexes for treating UC and help develop better processing methods.

Identification of novel non-toxic and anti-angiogenic α-fluorinated chalcones as potent colchicine binding site inhibitors

α-Fluorinated chalcones were prepared and evaluated for their cell growth inhibitory properties against six human cancer cell lines. The most potent chalcone 4c demonstrated excellent selective toxicity against cancer cells versus normal human cells, with IC₅₀ values at nanomolar concentration ranges against 5 cancer cell lines. A further study revealed that 4c could bind to the colchicine site of tubulin, disrupt the cell microtubule networks, and effectively inhibit tubulin polymerisation. Cellular-based mechanism studies elucidated that 4c arrested MGC-803 cell cycle at G2/M phase. In addition, 4c dose-dependently caused Caspase-induced apoptosis of MGC-803 cells through mitochondrial dysfunction. Notably, compound 4c was found to inhibit the HUVECs tube formation, migration, and invasion in vitro. Furthermore, our data suggested that treatment with 4c significantly reduced MGC-803 cells metastasis and proliferation in vitro. Overall, this work showed that chalcone hybrid 4c is a potent inhibitor of tubulin assembly with prominent anti-angiogenesis and anti-cancer properties.

Angiogenesis, Anti-Tumor, and Anti-Metastatic Activity of Novel α-Substituted Hetero-Aromatic Chalcone Hybrids as Inhibitors of Microtubule Polymerization

A library of new heteroaromatic ring-linked chalcone analogs were designed and synthesized of these, compound 7m with α-CH₃ substitution and bearing a benzofuran ring, displaying the most potent activity, with IC₅₀ values of 0.07–0.183 µM against three cancer cells. Its low cytotoxicity toward normal human cells and strong potency on drug-resistant cells revealed the possibility for cancer therapy. It also could moderately inhibit in vitro tubulin polymerization with an IC₅₀ value of 12.23 µM, and the disruption of cellular architecture in MCF-7 cells was observed by an immunofluorescence assay. Cellular-based mechanism studies elucidated that 7m arrested the cell cycle at the G2/M phase and induced apoptosis by regulating the expression levels of caspases and PARP protein. Importantly, the compound 7 m was found to inhibit HUVEC tube formation, migration, and invasion in vitro. In vivo assay showed that 7m could effectively destroy angiogenesis of zebrafish embryos. Furthermore, our data suggested that treatment with 7m significantly reduced MCF-7 cell metastasis and proliferation in vitro and in zebrafish xenograft. Collectively, this work showed that chalcone hybrid 7m deserves further investigation as dual potential tubulin polymerization and angiogenesis inhibitor.

A long way to go: caspase inhibitors in clinical use

Caspases are an evolutionary conserved family of cysteine-dependent proteases that are involved in many vital cellular processes including apoptosis, proliferation, differentiation and inflammatory response. Dysregulation of caspase-mediated apoptosis and inflammation has been linked to the pathogenesis of various diseases such as inflammatory diseases, neurological disorders, metabolic diseases, and cancer. Multiple caspase inhibitors have been designed and synthesized as a potential therapeutic tool for the treatment of cell death-related pathologies. However, only a few have progressed to clinical trials because of the consistent challenges faced amongst the different types of caspase inhibitors used for the treatment of the various pathologies, namely an inadequate efficacy, poor target specificity, or adverse side effects. Importantly, a large proportion of this failure lies in the lack of understanding various caspase functions. To overcome the current challenges, further studies on understanding caspase function in a disease model is a fundamental requirement to effectively develop their inhibitors as a treatment for the different pathologies. Therefore, the present review focuses on the descriptive properties and characteristics of caspase inhibitors known to date, and their therapeutic application in animal and clinical studies. In addition, a brief discussion on the achievements, and current challenges faced, are presented in support to providing more perspectives for further development of successful therapeutic caspase inhibitors for various diseases.

Antitumor Effects of Carvacrol and Thymol: A Systematic Review

Background: It is estimated that one in five people worldwide faces a diagnosis of a malignant neoplasm during their lifetime. Carvacrol and its isomer, thymol, are natural compounds that act against several diseases, including cancer. Thus, this systematic review aimed to examine and synthesize the knowledge on the antitumor effects of carvacrol and thymol.

Methods: A systematic literature search was carried out in the PubMed, Web of Science, Scopus and Lilacs databases in April 2020 (updated in March 2021) based on the PRISMA 2020 guidelines. The following combination of health descriptors, MeSH terms and their synonyms were used: carvacrol, thymol, antitumor, antineoplastic, anticancer, cytotoxicity, apoptosis, cell proliferation, in vitro and in vivo. To assess the risk of bias in in vivo studies, the SYRCLE Risk of Bias tool was used, and for in vitro studies, a modified version was used.

Results: A total of 1,170 records were identified, with 77 meeting the established criteria. The studies were published between 2003 and 2021, with 69 being in vitro and 10 in vivo. Forty-three used carvacrol, 19 thymol, and 15 studies tested both monoterpenes. It was attested that carvacrol and thymol induced apoptosis, cytotoxicity, cell cycle arrest, antimetastatic activity, and also displayed different antiproliferative effects and inhibition of signaling pathways (MAPKs and PI3K/AKT/mTOR).

Conclusions: Carvacrol and thymol exhibited antitumor and antiproliferative activity through several signaling pathways. In vitro, carvacrol appears to be more potent than thymol. However, further in vivo studies with robust methodology are required to define a standard and safe dose, determine their toxic or side effects, and clarify its exact mechanisms of action.

This systematic review was registered in the PROSPERO database (CRD42020176736) and the protocol is available at https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=176736.

Dehydroabietic Acid Is a Novel Survivin Inhibitor for Gastric Cancer

Gastric cancer is a malignant tumor with a high incidence and mortality rate worldwide. Nevertheless, anticancer drugs that can be used for gastric cancer treatment are limited. Therefore, it is important to develop targeted anticancer drugs for the treatment of gastric cancer. Dehydroabietic acid (DAA) is a diterpene found in tree pine. Previous studies have demonstrated that DAA inhibits gastric cancer cell proliferation by inducing apoptosis. However, we did not know how DAA inhibits the proliferation of gastric cancer cells through apoptosis. In this study, we attempted to identify the genes that induce cell cycle arrest and cell death, as well as those which are altered by DAA treatment. DAA-regulated genes were screened using RNA-Seq and differentially expressed genes (DEGs) analysis in AGS cells. RNA-Seq analysis revealed that the expression of survivin, an apoptosis inhibitor, was significantly reduced by DAA treatment. We also confirmed that DAA decreased survivin expression by RT-PCR and Western blotting analysis. In addition, the ability of DAA to inhibit survivin was compared to that of YM-155, a known survivin inhibitor. DAA was found to have a stronger inhibitory effect in comparison with YM-155. DAA also caused an increase in cleaved caspase-3, an apoptosis-activating protein. In conclusion, DAA is a potential anticancer agent for gastric cancer that inhibits survivin expression.

Synthesis and in vitro biological evaluation of novel dendrocandin analogue as potential anti-tumor agent

Dendrocandins are characteristic chemical structures of D. officinale and have strong physiological bioactivities. In this study, a dendrocandin analogue (1) has been prepared by total synthesis (9 steps, 12.6% overall yield) in which coupling reaction and Wittig reaction as the key steps. Compound 1 was also evaluated for its anticancer activity in vitro against six human cancer cells (MCF-7, A549, A431, SW480, HepG-2 and HL-60) using MTT assays. Compound 1 showed potent cytotoxicity, with the IC50 value 16.27 ± 0.26 µM. The expression levels of apoptotic proteins indicated that compound 1 can up-regulate the expression of apoptotic proteins, leading to apoptosis. This compound suggested that it's potential as anticancer agent for further development.

Gigantol inhibits proliferation and enhances DDP-induced apoptosis in breast-cancer cells by downregulating the PI3K/Akt/mTOR signaling pathway

AIMS

Gigantol is a bibenzyl compound isolated from orchids of the genus Dendrobium. Gigantol has been demonstrated to possess various pharmacologic (including anticancer) effects. Cisplatin (DDP) has been used and studied as the first-line agent for breast cancer (BC) treatment. Often, its efficacy is jeopardized due to intolerance and organ toxicity. We investigated if gigantol could enhance the anticancer effects of DDP in BC cells and its underlying mechanism of action.

MAIN METHODS

The potential pathway of gigantol in BC cells was detected by network-pharmacology and molecular-docking studies. The proliferation and apoptosis of BC cell lines were measured by the MTT assay, colony formation, Hoechst-33342 staining, and flow cytometry. Protein expression was measured by western blotting.

KEY FINDINGS

Gigantol could inhibit proliferation of BC cells and enhance DDP-induced apoptosis. According to the results of western blotting, gigantol reinforced DDP-induced anticancer effects through downregulation of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway in BC cells. The effects were consistent with those of the pathway inhibitor LY294002.

SIGNIFICANCE

Our data might provide new insights into the underlying antitumor effect of gigantol in BC cells. This enhancement effect in the combination of gigantol and DDP may provide many therapeutic benefits in clinical treatment regimens against BC.

Discovery of novel N-benzylbenzamide derivatives as tubulin polymerization inhibitors with potent antitumor activities

A series of novel N-benzylbenzamide derivatives were designed and synthesized as tubulin polymerization inhibitors. Among fifty-one target compounds, compound 20b exhibited significant antiproliferative activities with IC₅₀ values ranging from 12 to 27 nM against several cancer cell lines, and possessed good plasma stability and satisfactory physicochemical properties. Mechanism studies demonstrated that 20b bound to the colchicine binding site and displayed potent anti-vascular activity. Notably, the corresponding disodium phosphate 20b-P exhibited an excellent safety profile with the LD₅₀ value of 599.7 mg/kg (i.v. injection), meanwhile, it significantly inhibited tumor growth and decreased microvessel density in liver cancer cell H22 allograft mouse model without obvious toxicity. Collectively, 20b and 20b-P are novel promising anti-tubulin agents with more druggable properties and deserve to be further investigated for cancer therapy.

Curcumin anti-tumor effects on endometrial cancer with focus on its molecular targets

Curcumin is extracted from turmeric and shows a variety of properties that make it a useful agent for treating diseases and targeting different biological mechanisms, including apoptosis, angiogenesis, inflammation, and oxidative stress. This phenolic compound is safe even at high doses. However, it has poor bioavailability. The incidence rates of endometrial cancer (EC) that is one of the most prevalent gynecological malignancies is increasing. Meanwhile, the onset age of EC has been decreased in past few years. Besides, EC does not show a convenient prognosis, particularly at advanced stages. Based on this information, discovering new approaches or enhancing the available ones is required to provide better care for EC patients. In this review, we cover studies concerned with the anti-tumor effects of curcumin on EC. We focus on molecular mechanisms that are targeted by curcumin treatment in different processes of cancer development and progression, such as apoptosis, inflammation, and migration. Furthermore, we present the role of curcumin in targeting some microRNAs (miRNAs) that may play a role in EC.

Design, synthesis, and cytotoxic activity of novel 2H-imidazo[1,2-c]pyrazolo[3,4-e]pyrimidine derivatives

In this study, a series of novel 2H-imidazo [1, 2-c] pyrazolo [3, 4-e] pyrimidine derivatives were designed, synthesized, and evaluated for their cytotoxic activities. The in vitro cell growth inhibition assay of the target compounds indicated their selectivity in inhibiting the proliferation of blood tumor cells (K562, U937) and solid tumor cells (HCT116, HT-29). Compound 9b exhibited the highest antiproliferative activities against K562 (IC₅₀ = 5.597 µM) and U937 (IC₅₀ = 3.512 µM). Based on the flow cytometry assays, compound 9b caused obvious induction of cell apoptosis and cell arrest at the S phase. Furthermore, western blot analysis revealed that compound 9b upregulated the expression of Bax, downregulated the levels of Bcl-2, and further activated caspase-3 in K562 cells. Therefore, compound 9b may be a potential anticancer agent that deserves further investigation.

Tracking exogenous intracellular casp-3 using split GFP

Cytosolic protein delivery promises diverse applications from therapeutics, to genetic modification and precision research tools. To achieve effective cellular and subcellular delivery, approaches that allow protein visualization and accurate localization with greater sensitivity are essential. Fluorescently tagging proteins allows detection, tracking and visualization in cellulo. However, undesired consequences from fluorophores or fluorescent protein tags, such as nonspecific interactions and high background or perturbation to native protein's size and structure, are frequently observed, or more troublingly, overlooked. Distinguishing cytosolically released molecules from those that are endosomally entrapped upon cellular uptake is particularly challenging and is often complicated by the inherent pH-sensitive and hydrophobic properties of the fluorophore. Monitoring localization is more complex in delivery of proteins with inherent protein-modifying activities like proteases, transacetylases, kinases, etc. Proteases are among the toughest cargos due to their inherent propensity for self-proteolysis. To implement a reliable, but functionally silent, tagging technology in a protease, we have developed a caspase-3 variant tagged with the 11th strand of GFP that retains both enzymatic activity and structural characteristics of wild-type caspase-3. Only in the presence of cytosolic GFP strands 1-10 will the tagged caspase-3 generate fluorescence to signal a non-endosomal location. This methodology facilitates easy screening of cytosolic vs. endosomally-entrapped proteins due to low probabilities for false positive results, and further, allows tracking of the resultant cargo's translocation. The development of this tagged casp-3 cytosolic reporter lays the foundation to probe caspase therapeutic properties, charge-property relationships governing successful escape, and the precise number of caspases required for apoptotic cell death.

Progesterone induces apoptosis by activation of caspase-8 and calcitriol via activation of caspase-9 pathways in ovarian and endometrial cancer cells in vitro

Previously we have shown inhibition of endometrial cancer cell growth with progesterone and calcitriol. However, the mechanisms by which the two agents attenuate proliferation have not been well characterized yet. Herein, we investigated how progesterone and calcitriol induce apoptosis in cancer cells. DNA fragmentation was upregulated by progesterone and calcitriol in ovarian and endometrial cancer cells. Time-dependent treatment of ovarian cancer cells, ES-2, and TOV-21G with progesterone enhanced caspase -8 activity after 12 h, whereas OV-90, TOV-112D, HEC-1A, and HEC-59 cells showed increased activity after 24 h. Caspase 9 activity was increased in all cell lines after 24 h treatment with calcitriol. Pretreatment of cancer cells with a caspase-8 inhibitor (z-IETD-fmk) or caspase-9 inhibitor (Z-LEHD-fmk) significantly attenuated progesterone and calcitriol induced caspase-8 and caspase-9 expression, respectively. The expression of FasL, Fas, FAD, and pro-caspase-8, which constitute the death-inducing signaling complex (DISC), was upregulated in progesterone treated cancer cells. Knockdown of FAS or FADD with specific siRNAs significantly blocked progesterone-induced caspase-8. Cleavage of the BID was not affected by caspase-8 activation suggesting the absence of cross-talk between caspase-8 and caspase-9 pathways. Calcitriol treatment decreased mitochondrial membrane potential and increased the release of cancer cytochrome C. These findings indicate that progesterone induces apoptosis through activation of caspase-8 and calcitriol through caspase-9 activation in cancer cells. A combination of progesterone-calcitriol activates both extrinsic and intrinsic apoptotic pathways in cancer cells.

Effects of MC-LR on histological structure and cell apoptosis in the kidney of grass carp (Ctenopharyngodon idella)

Microcystin-LR (MC-LR) is a well-known hepatotoxin; however, increasing evidence suggests that it might induce kidney injury. Grass carp (Ctenopharyngodon idella) is one of the most important farmed species and may be affected by MC-LR releasing into waterbody during cyanobacterial bloom. Here, this present study aimed to explore the nephrotoxicity of grass carp by MC-LR. The grass carp received a single intraperitoneal injection of different doses of MC-LR (0, 25, 75, and 100 μg/kg body weight (BW)), and the kidneys were isolated at 24 and 96 h post-injection (hpi). Histopathological examination revealed kidney lesions, with severe hemorrhage, necrosis of the interstitium, and dilation of Bowman's capsule in the 75 and 100 μg MC-LR/kg BW groups. Under transmission electron microscopy, a larger number of swelling and vacuolated degeneration of mitochondria were observed; moreover, apoptotic features, such as condensed chromatin and shrinkage of cells, were observed in the 75 and 100 μg MC-LR/kg BW groups at 96 hpi. MC-LR significantly upregulated the number of apoptotic cells in the 75 and 100 μg/kg BW groups at 96 hpi as indicated by terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay (P < 0. 05). The results of quantitative assays showed that the mRNA expression of Bax, caspase-9, and caspase-3 in grass carp kidney were significantly increased at 96 hpi in the 75 and 100 μg MC-LR/kg BW groups compared with that in the control group, but Bcl-2 mRNA expression was significantly decreased in all the treatment groups at 24 and 96 hpi. Taken together, these results indicated that MC-LR damaged the kidney structure and resulted in renal apoptosis which may occur via the mitochondrial pathway.

Redox Regulation by Protein S-Glutathionylation: From Molecular Mechanisms to Implications in Health and Disease

S-glutathionylation, the post-translational modification forming mixed disulfides between protein reactive thiols and glutathione, regulates redox-based signaling events in the cell and serves as a protective mechanism against oxidative damage. S-glutathionylation alters protein function, interactions, and localization across physiological processes, and its aberrant function is implicated in various human diseases. In this review, we discuss the current understanding of the molecular mechanisms of S-glutathionylation and describe the changing levels of expression of S-glutathionylation in the context of aging, cancer, cardiovascular, and liver diseases.

Protective Effects of Oenothera biennis against Hydrogen Peroxide-Induced Oxidative Stress and Cell Death in Skin Keratinocytes

BACKGROUND

Oenothera biennis (evening primrose) produces bioactive substances with a diverse range of pharmacological functions. However, it is currently unknown whether extract prepared from the aerial parts of O. biennis (APOB) can protect the skin against oxidative stress.

OBJECTIVE

The aim of this study is to investigate the protective effects of APOB against oxidative stress-induced damage in human skin keratinocytes (HaCaT) and elucidate the underlying mechanisms.

METHODS

We pretreated HaCaT cells with various concentrations of APOB or the antioxidant N-acetyl-L-cysteine before applying H₂O₂. We then compared the cell viability, intracellular reactive oxygen species (ROS) production, and DNA and mitochondrial damage between pretreated and untreated control cells using a range of assays, flow cytometry, and Western blot analysis and also examined the reducing power and DPPH free radical scavenging activity of APOB.

RESULTS

APOB pretreatment significantly increased cell viability, effectively attenuated H₂O₂-induced comet tail formation, and inhibited H₂O₂-induced phosphorylation of the histone γH2AX, as well as the number of apoptotic bodies and Annexin V-positive cells. APOB was found to have high reducing power and DPPH radical scavenging activity and also exhibited scavenging activity against intracellular ROS accumulation and restored the loss of mitochondrial membrane potential caused by H₂O₂. APOB pretreatment almost totally reversed the enhanced cleavage of caspase-3, the degradation of poly (ADP-ribose)-polymerase (PARP), DNA fragmentation that usually occurs in the presence of H₂O₂, and increased the levels of heme oxygenase-1 (HO-1), a potent antioxidant enzyme that is associated with the induction of nuclear factor-erythroid 2-related factor 2 (Nrf2).

CONCLUSIONS

APOB can protect HaCaT cells from H₂O₂-induced DNA damage and cell death by blocking cellular damage related to oxidative stress via a mechanism that affects ROS elimination and by activating the Nrf2/HO-1 signaling pathway.

The role of caspase-8 in the tumor microenvironment of ovarian cancer

Caspase-8 is an aspartate-specific cysteine protease, which is best known for its apoptotic functions. Caspase-8 is placed at central nodes of multiple signal pathways, regulating not only the cell cycle but also the invasive and metastatic cell behavior, the immune cell homeostasis and cytokine production, which are the two major components of the tumor microenvironment (TME). Ovarian cancer often has dysregulated caspase-8 expression, leading to imbalance between its apoptotic and non-apoptotic functions within the tumor and the surrounding milieu. The downregulation of caspase-8 in ovarian cancer seems to be linked to high aggressiveness with chronic inflammation, immunoediting, and immune resistance. Caspase-8 plays therefore an essential role not only in the primary tumor cells but also in the TME by regulating the immune response, B and T lymphocyte activation, and macrophage differentiation and polarization. The switch between M1 and M2 macrophages is possibly associated with changes in the caspase-8 expression. In this review, we are discussing the non-apoptotic functions of caspase-8, highlighting this protein as a modulator of the immune response and the cytokine composition in the TME. Considering the low survival rate among ovarian cancer patients, it is urgently necessary to develop new therapeutic strategies to optimize the response to the standard treatment. The TME is highly heterogenous and provides a variety of opportunities for new drug targets. Given the variety of roles of caspase-8 in the TME, we should focus on this protein in the development of new therapeutic strategies against the TME of ovarian cancer.

Design, synthesis, and evaluation of novel N'-substituted-1-(4-chlorobenzyl)-1H-indol-3-carbohydrazides as antitumor agents

In continuity of our search for novel anticancer agents acting as procaspase activators, we have designed and synthesised two series of (E)-N′-benzylidene-carbohydrazides (4a–m) and (Z)-N'-(2-oxoindolin-3-ylidene)carbohydrazides (5a–g) incorporating 1-(4-chlorobenzyl)-1H-indole core. Bioevaluation showed that the compounds, especially compounds in series 4a–m, exhibited potent cytotoxicity against three human cancer cell lines (SW620, colon cancer; PC-3, prostate cancer; NCI-H23, lung cancer). Within series 4a–m, compounds with 2-OH substituent (4g–i) exhibited very strong cytotoxicity in three human cancer cell lines assayed with IC₅₀ values in the range of 0.56–0.83 µM. In particular, two compounds 4d and 4f bearing 4-Cl and 4-NO₂ substituents, respectively, were the most potent in term of cytotoxicity with IC₅₀ values of 0.011–0.001 µM. In caspase activation assay, compounds 4b and 4f were found to activate caspase activity by 314.3 and 270.7% relative to PAC-1. This investigation has demonstrated the potential of these simple acetohydrazides, especially compounds 4b, 4d, and 4f, as anticancer agents.

Evaluation of Caspase-3 Activity During Apoptosis with Fluorescence Lifetime-Based Cytometry Measurements and Phasor Analyses

Caspase-3 is a well-described protease with many roles that impact the fate of a cell. During apoptosis, caspase-3 acts as an executioner caspase with important proteolytic functions that lead to the final stages of programmed cell death. Owing to this key role, caspase-3 is exploited intracellularly as a target of control of apoptosis for therapeutic outcomes. Yet the activation of caspase-3 during apoptosis is challenged by other roles and functions (e.g., paracrine signaling). This brief report presents a way to track caspase-3 levels using a flow cytometer that measures excited state fluorescence lifetimes and a signal processing approach that leads to a graphical phasor-based interpretation. An established Förster resonance energy transfer (FRET) bioprobe was used for this test; the connected donor and acceptor fluorophore is cleavable by caspase-3 during apoptosis induction. With the cell-by-cell decay kinetic data and phasor analyses we generate a caspase activation trajectory, which is used to interpret activation throughout apoptosis. When lifetime-based cytometry is combined with a FRET bioprobe and phasor analyses, enzyme activation can be simplified and quantified with phase and modulation data. We envision extrapolating this approach to high content screening, and reinforce the power of phasor approaches with cytometric data. Analyses such as these can be used to cluster cells by their phase and modulation "lifetime fingerprint" when the intracellular fluorescent probe is utilized as a sensor of enzyme activity. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC on behalf of International Society for Advancement of Cytometry.

Cassaine Diterpenoid Amide from Stem Bark of Erythrophleum fordii Suppresses Cytotoxic and Induces Apoptosis of Human Leukemia Cells

Cassaine diterpenoids amides from the stem bark of Vietnamese Erythrophleum fordii Oliver were screened for their cytotoxic activity against human cancer cells. The cell proliferation assay results showed that, among the active compounds, 3β-acetyl-nor-erythrophlamide (3AEP) exhibited the most potential cytotoxicity against human leukemia HL-60 and KG cells with IC₅₀ values of 12.0 ± 1.2 and 18.1 ± 2.7 µM, respectively. Treatment of 3AEP resulted in the apoptosis of HL-60 cells via the activation of caspase 3, and poly (ADP-ribose) polymerase (PARP). Molecular docking in silico results showed that the 3AEP can bind to both the procaspase-3 allosteric site and the PARP-1 active site, with binding energies of −7.51 and −9.63 kcal/mol respectively. These results indicated that the stem bark of Vietnamese E. fordii and its cassaine diterpenoid amides may be useful in the apoptosis induction of human leukemia cancer cells.

Lestaurtinib potentiates TRAIL-induced apoptosis in glioma via CHOP-dependent DR5 induction

Lestaurtinib, also called CEP-701, is an inhibitor of tyrosine kinase, causes haematological remission in patients with AML possessing FLT3-ITD (FLT3 gene) internal tandem duplication and strongly inhibits tyrosine kinase FLT3. Treatment with lestaurtinib modulates various signalling pathways and leads to cell growth arrest and programmed cell death in several tumour types. However, the effect of lestaurtinib on glioma remains unclear. In this study, we examined lestaurtinib and TRAIL interactions in glioma cells and observed their synergistic activity on glioma cell apoptosis. While U87 and U251 cells showed resistance to TRAIL single treatment, they were sensitized to apoptosis induced by TRAIL in the presence of lestaurtinib because of increased death receptor 5 (DR5) levels through CHOP-dependent manner. We also demonstrated using a xenograft model of mouse that the tumour growth was absolutely suppressed because of the combined treatment compared to TRAIL or lestaurtinib treatment carried out singly. Our findings reveal a potential new strategy to improve antitumour activity induced by TRAIL in glioma cells using lestaurtinib through a mechanism dependent on CHOP.

Synergistic Effect of Benzethonium Chloride Combined with Endoxan against Hepatocellular Carcinoma in Rats through Targeting Apoptosis Signaling Pathway

Combination therapy has been the trendy of care, particularly in cancer remedy, since it is a rational approach to increase response and tolerability and to diminish resistance. Hence, there is a growing interest in combining anticancer drugs to maximizing efficacy with minimum systemic toxicity through the delivery of lower drug doses. Therefore, in the present study, the value of combination between benzethonium chloride (benzo) and endoxan (endo) as anti-tumor drug sensitization of hepatocellular carcinoma HCC treatment were detected both in vitro and in vivo. Crystal violet test was performed to detect the proliferation of HepG2 cells treated with benzo or/and endo. In addition, the HCC rat model was established by diethylnitrosamine (DEN) administration. The antitumor effect was enhanced with the combined treatment of the two drugs, particularly in the group with benzo and endo. The results confirmed that the HCC condition was developed in response to lower expressions of caspase 3 and P53 which, in turn, was due to the overexpression of Bcl-2, and downregulation of cytochrome C. The treatment with benzo combined with endo caused significant activation of caspase-3 mediated apoptotic signals that could be responsible for its anti-HCC potential. Meantime, benzo combined with endo treatments could reduce the hepatocellular carcinogenesis by reducing the expression of MMP-9. Therefore, benzo and endo treatments may be a hopeful therapeutic drug for HCC. Also, more studies are recommended to feat the idea of this research for medical use.

Cytotoxicity of the Sesquiterpene Lactone Spiciformin and Its Acetyl Derivative against the Human Leukemia Cell Lines U-937 and HL-60

Spiciformin (1) is a sesquiterpene lactone with a germacrane skeleton that is found in two Tanacetum species endemic to the Canary Islands. In this study, the cytotoxicities of 1 and its acetyl derivative (2) were evaluated against human tumor cells. These sesquiterpene lactones were cytotoxic against human acute myeloid leukemia (U-937 and HL-60) cells, even in cells over-expressing the pro-survival protein Bcl-2, but melanoma (SK-MEL-1) and human mononuclear cells isolated from blood of healthy donors were more resistant. Both compounds are apoptotic inducers in human leukemia U-937 cells. Cell death was mediated by the processing and activation of initiator and effector caspases and the cleavage of poly(ADP-ribose) polymerase, and it was blocked by a broad-spectrum caspase inhibitor and (in the case of sesquiterpene lactone 2) by the selective caspase-3/7, -8, and -9 inhibitors. In addition, certainly in the case of compound 2, this was found to be associated with a decrease in mitochondrial membrane potential, downregulation of the anti-apoptotic protein Bcl-2, activation of the mitogen-activated protein kinases signaling pathway, and generation of reactive oxygen species. It will, therefore, be relevant to continue characterization of this class of compounds.

Beneficial effect of fluoxetine on anti-tumor progression on hepatocellular carcinoma and non-small cell lung cancer bearing animal model

Fluoxetine, an antidepressant, has been indicated to elicit anti-cancer response in hepatocellular carcinoma (HCC) and non-small cell lung cancer (NSCLC) in vitro. However, anticancer effect and mechanism of fluoxetine in HCC and NSCLC in vivo still needs to be elucidated. In this study, we showed anticancer efficacy and inhibitory mechanism of fluoxetine on the tumor progression of HCC and NSCLC in vivo. Tumor growth was significantly inhibited with fluoxetine treatment in HCC and NSCLC in vivo. Fluoxetine obviously decreased expression of cell proliferative, anti-apoptotic, invasion-associated proteins including Cyclin-D1, survivin, vascular endothelial growth factor (VEGF), matrix metallopeptidase 9 (MMP-9) and urokinase-type plasminogen activator (uPA). Importantly, fluoxetine diminished the phosphorylation of NF-κB p65 which recognized as one of the critical transcription factors in tumor progression. Inhibition of AKT or extracellular signal-regulated kinases (ERK) phosphorylation was linked to NF-κB inactivation in NSCLC or HCC in vitro. Furthermore, expression of AKT or ERK phosphorylation was effectively attenuated by fluoxetine treatment in NSCLC or HCC in vivo. In addition, fluoxetine also triggered extrinsic/intrinsic apoptotic signaling by activating caspase-3, -8, and -9 in HCC and NSCLC. Our findings suggest that fluoxetine may represent as a promising adjuvant for patients with HCC or NSCLC. In conclude, the results also suggested the blockage of AKT/NF-κB or ERK/NF-κB activation and the induction of apoptosis are associated with fluoxetine-inhibited tumor progression of HCC or NSCLC in vivo.

Licochalcone H Synthesized by Modifying Structure of Licochalcone C Extracted from Glycyrrhiza inflata Induces Apoptosis of Esophageal Squamous Cell Carcinoma Cells

Esophageal cancer is one of the malignant cancers with a low 5-year survival rate. Licochalcone (LC) H, a chemically synthesized substance, is a regioisomer of LCC extracted from licorice. The purpose of this study was to determine whether LCH might have anticancer effect on human esophageal squamous cell carcinoma (ESCC) cell lines via apoptosis signaling pathway. After 48 h of treatment, IC₅₀ of LCH in KYSE 30, KYSE 70, KYSE 410, KYSE 450, and KYSE 510 cells were 15, 14, 18, 15, and 16 μM, respectively. This study demonstrated that LCH potently suppressed proliferation of ESCC cells in a concentration- and time-dependent manner. LCH triggered G2/M-phase arrest by modulating expression levels of cdc2, cyclin B1, p21, and p27. LCH also induced apoptosis of ESCC cells through reactive oxygen species-mediated endoplasmic reticulum (ER) stress via JNK/p38 activation pathways. The anticancer effect of LCH was associated with ER stress and mitochondrial dysfunction. It also affected protein levels of Mcl-1, tBid, Bax, Bcl-2, cytochrome c, Apaf-1, PARP, cleaved-PARP, and ER stress-related proteins (GRP78 and CHOP). Our findings provide the first demonstration that LCH has anticancer effect on ESCC. Thus, LCH might have potential for preventing and/or treating human ESCC.

In vivo acute toxicity evaluation and in vitro molecular mechanism study of antiproliferative activity of a novel indole Schiff base β-diiminato manganeseIII complex in hormone-dependent and triple negative breast cancer cells

Breast cancer is the most frequently diagnosed cancer among women worldwide. Recently, increasing attention has been paid to the anticancer effects of transition metal complexes of indole Schiff bases. β-diiminato Manganese^III complex has shown promising cell cycle arrest and apoptosis induction against MCF-7 and MDA-MB-231 breast cancer cells. In this study, time- and dose- dependent inhibitory activity were evaluated using MTT assay after 48 h and 72 h exposure time. In addition, median effect analysis was conducted according to Chou-Talalay method to investigate whether Mn^III complex has synergistic effect in combination with chemotherapeutic drugs on inhibiting breast cancer cell growth. The molecular mechanisms underlying its potent antiproliferative effect was determined through bioluminescent caspase-3/7, -8 and -9 activity assays and quantitative expression analysis of cell cycle- and apoptosis-related genes. Furthermore, safety evaluation of Mn^III complex was assessed through the acute oral toxicity test in in vivo model. The MTT assay results revealed that it potently reduced the viability of MCF-7 (IC₅₀ of 0.63 ± 0.07 µg/mL for 48 h and 0.39 ± 0.08 µg/mL for 72 h) and MDA-MB-231 (1.17 ± 0.06 µg/mL for 48 h, 1.03 ± 0.15 µg/mL for 72 h) cells in dose- and time-dependent manner. Combination treatment also enhanced the cytotoxic effects of doxorubicin but not tamoxifen on inhibiting breast cancer cell growth. The involvement of intrinsic and extrinsic pathway in apoptosis induction was exhibited through the increased activity of caspase-9 and caspase-8, respectively, leading to enhanced downstream executioner caspase-3/7 activity in treated MCF-7 and MDA-MB-231 cells. In addition, gene expression analysis revealed that Mn^III complex exerts its antiproliferative effect via up-and down-regulation of p21 and cyclin D1, respectively, along with increased expression of Bax/Bcl-2 ratio, TNF-α, initiator caspase-8 and -10 and effector caspase-3 in MCF-7 and MDA-MB-231 cells. However, the results did not show increased caspase-8 activity in treated MCF-7 cells. Furthermore, in vivo acute oral toxicity test revealed no signs of toxicity and mortality in treated animal models compared to the control group. Collectively, the promising inhibitory effect and molecular and mechanistic evidence of antiproliferative activity of Mn^III complex and its safety characterization have demonstrated that it may have therapeutic value in breast cancer treatment worthy of further investigation and development.

Treatment with flaxseed oil induces apoptosis in cultured malignant cells

Flaxseed oil is widely recognized for its exceptional nutritional value, high concentration of fiber-based lignans and large amounts of ω-fatty acids. It is one of a generic group of functional foods that is often taken by cancer patients as a potential treatment. We have examined the anti-cancer effects of flaxseed oil by studying its direct effects on cancer cell growth in vitro. Treatment of a variety of cancer cell lines with flaxseed oil decreased their growth in a dose-dependent manner while non-malignant cell lines showed small increases in cell growth. Cells treated with a mixture of fatty acids, including α-linolenic acid, docosahexaenoic acid, and eicosapentaenoic acid and lignans including enterodiol and enterolactone was also able to decrease the growth of cancer cells. Treatment of B16-BL6 murine melanoma and MCF-7 breast cancer cells with flaxseed oil induced apoptosis as determined by changes in cell morphology, annexin V staining, DNA fragmentation and/or caspase activation. In addition, treatment with flaxseed oil also disrupted mitochondrial function in B16-BL6 and MCF-7 cells. These results indicate that flaxseed oil can specifically inhibit cancer cell growth and induce apoptosis in some cancer cells and suggests it has further potential in anti-cancer therapy.

Design, Synthesis, and Biological Evaluation of Novel Biotinylated Podophyllotoxin Derivatives as Potential Antitumor Agents

Podophyllotoxin has long been used as an active substance for cytotoxic activity. Fourteen novel biotinylated podophyllotoxin derivatives were designed, synthesized, and evaluated for cytotoxic activity for this study. The synthesized compounds were evaluated for cytotoxic activity in the following human cancer cell lines, SW480, MCF-7, A-549, SMMC-7721, and HL-60 by MTT assay. Most of them exhibited potent cytotoxic effects and compound 15 showed the highest cytotoxic activity among the five cancer cell lines tested, having its IC50 values in the range of 0.13 to 0.84 μM. Apoptosis analysis revealed that compound 15 caused obvious induction of cell apoptosis. Compound 15 significantly down-regulated the expression level of the marker proteins (caspase-3 and PARP) in H1299 and H1975 cells, activated the transcription of IRE1α, increased the expression of GRP78 and XBP-1s, and finally induced apoptosis of H1299 cells. In vivo studies showed that 15 at a dose of 20 mg/kg suppressed tumor growth of S180 cell xenografts in icr mice significantly. Further molecular docking studies suggested that compound 15 could bind well with the ATPase domain of Topoisomerase-II. These data suggest that compound 15 is a promising agent for cancer therapy deserving further research.

Understanding Apoptosis and Apoptotic Pathways Targeted Cancer Therapeutics

Various physiological processes involve appropriate tissue developmental process and homeostasis - the pathogenesis of several diseases connected with deregulatory apoptosis process. Apoptosis plays a crucial role in maintaining a balance between cell death and division, evasion of apoptosis results in the uncontrolled multiplication of cells leading to different diseases such as cancer. Currently, the development of apoptosis targeting anticancer drugs has gained much interest since cell death induced by apoptosis causes minimal inflammation. The understanding of complexities of apoptosis mechanism and how apoptosis is evolved by tumor cells to oppose cell death has focused research into the new strategies designed to induce apoptosis in cancer cells. This review focused on the underlying mechanism of apoptosis and the dysregulation of apoptosis modulators involved in the extrinsic and intrinsic apoptotic pathway, which include death receptors (DRs) proteins, cellular FLICE inhibitory proteins (c-FLIP), anti-apoptotic Bcl-2 proteins, inhibitors of apoptosis proteins (IAPs), tumor suppressor (p53) in cancer cells along with various current clinical approaches aimed to selectively induce apoptosis in cancer cells.

Induction of Apoptosis Scutellaria baicalensis Georgi Root Extract by Inactivation of the Phosphatidyl Inositol 3-kinase/Akt Signaling Pathway in Human Leukemia U937 Cells

Background

The roots of Scutellaria baicalensis Georgi (Labiatae) have been widely used in traditional medicine for treatment of various diseases. In this study, we investigated the effects of ethanol extracts of S. baicalensis roots (EESB) on the growth ofn human leukemia U937 cells.

Methods

The effect of EESB on cell viability was measured by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apoptosis was determined using 4,6-diamidino-2-phenyllindile staining and flow cytometry. The effects of EESB on the expression of regulatory proteins of apoptosis and phosphatidyl inositol 3-kinase (PI3K)/Akt signaling were determined by Western blotting. Caspase activity and mitochondrial membrane potential (MMP) were measured using flow cytometric analysis.

Results

EESB significantly inhibited the growth of U937 cells and induced apoptosis, which was associated with down-regulation of anti-apoptotic Bcl-2, up-regulation of pro-apoptotic Bax, the loss of MMP and activation of caspase-9 and -3. We also found that EESB enhanced the expression of death receptors (DRs) and their associated ligands and induced the activation of caspase-8 and truncation of Bid. In addition, EESB suppressed PI3K/Akt signaling and EESB-induced apoptosis and growth inhibition were further increased by inhibition of PI3K activity.

Conclusions

Our results indicated that the pro-apoptotic effect of EESB was mediated through the activation of DR-mediated intrinsic and mitochondria-mediated extrinsic apoptosis pathways and inhibition of the PI3K/Akt signaling in U937 cells.

Sanguinarine Induces Apoptosis Pathway in Multiple Myeloma Cell Lines via Inhibition of the JaK2/STAT3 Signaling

Sanguinarine (SNG), a benzophenanthridine alkaloid, has displayed various anticancer abilities in several vivo and in vitro studies. However, the anticancer potential of SNG is yet to be established in multiple myeloma (MM), a mostly incurable malignancy of plasma cells. In this study, we aimed to investigate the potential anti-proliferative and pro-apoptotic activities of SNG in a panel of MM cell lines (U266, IM9, MM1S, and RPMI-8226). SNG treatment of MM cells resulted in a dose-dependent decrease in cell viability through mitochondrial membrane potential loss and activation of caspase 3, 9, and cleavage of PARP. Pre-treatment of MM cells with a universal caspase inhibitor, Z-VAD-FMK, prevented SNG mediated loss of cell viability, apoptosis, and caspase activation, confirming that SNG-mediated apoptosis is caspase-dependent. The SNG-mediated apoptosis appears to be resulted from suppression of the constitutively active STAT3 with a concomitant increase in expression of protein tyrosine phosphatase (SHP-1). SNG treatment of MM cells leads to down-regulation of the anti-apoptotic proteins including cyclin D, Bcl-2, Bclxl, and XIAP. In addition, it also upregulates pro-apoptotic protein, Bax. SNG mediated cellular DNA damage in MM cell lines by induction of oxidative stress through the generation of reactive oxygen species and depletion of glutathione. Finally, the subtoxic concentration of SNG enhanced the cytotoxic effects of anticancer drugs bortezomib (BTZ) by suppressing the viability of MM cells via induction of caspase-mediated apoptosis. Altogether our findings demonstrate that SNG induces mitochondrial and caspase-dependent apoptosis, generates oxidative stress, and suppresses MM cell lines proliferation. In addition, co-treatment of MM cell lines with sub-toxic doses of SNG and BTZ potentiated the cytotoxic activity. These results would suggest that SNG could be developed into therapeutic agent either alone or in combination with other anticancer drugs in MM.

Antitumor activities of novel glycyrrhetinic acid-modified curcumin-loaded cationic liposomes in vitro and in H22 tumor-bearing mice

At present, the chemotherapy of advanced inoperable liver cancer is limited with serious side effects. Curcumin possesses multiple cancer preventive activities and low safety concerns. However, its poor solubility and instability in water pose significant pharmacological barriers to its clinical application. In this study, we presented a novel delivery system – the glycyrrhetinic acid modified curcumin-loaded cationic liposomes (GAMCLCL) and investigated its antitumor activities on HepG2 cells in vitro and in H22 tumor-bearing mice. The experimental results demonstrated that GAMCLCL was a cationic liposome and could be Intravenous administration. Compared to free curcumin, GAMCLCL exhibited stronger antitumor activities in vitro and in vivo. The antitumor results of GAMCLCL after intravenous administration were very similar to those after intratumoral administration. The main activities of GAMCLCL and curcumin included inhibition of HepG2 cell proliferation, inhibition of tumor growth, reduction of tumor microvascular density, down-regulation of the expression of VEGF protein, and up-regulation of the expression of Caspases3 protein in H22 tumor tissues. Furthermore, GAMCLCL improved the parameters of WBC, RBC, ALT, CRE, LDH of H22 tumor-bearing mice. Curcumin is a nontoxic natural compound with definite antitumor activities, its antitumor effects can be enhanced by preparation of GAMCLCL.

Microcystin-LR induces angiodysplasia and vascular dysfunction through promoting cell apoptosis by the mitochondrial signaling pathway

The harmful algal blooms are becoming increasingly problematic in the regions that drinking water production depends on surface waters. With a global occurrence, microcystins are toxic peptides produced by multiple cyanobacterial genera in the harmful algal blooms. In this study, we examined the effects of microcystin-LR (MC-LR), a representative toxin of the microcystin family, on vascular development in zebrafish and the apoptosis of human umbilical vein endothelial cells (HUVECs). In zebrafish larvae, MC-LR induced angiodysplasia, damaged vascular structures and reduced lumen size at 0.1 μM and 1 μM, leading to the decrease of the blood flow area in the blood vessels and brain hemorrhage, which showed that MC-LR could dose-dependently inhibit vascular development and cause vascular dysfunction. In MC-LR treated HUVECs, the proportion of early apoptosis and late apoptosis cells increased in a concentration-dependent manner. Different concentrations of MC-LR could also activate caspase 3/9 in HUVECs, increase the level of mitochondrial ROS and reduce mitochondrial membrane potential. Additionally, MC-LR could promote the expression of p53 and inhibit the expression of PCNA. The findings showed that MC-LR could promote apoptosis of HUVECs through the mitochondrial signaling pathway. Combined with these results, MC-LR may promote vascular endothelial cell apoptosis through mitochondrial signaling pathway, leading to angiodysplasia and vascular dysfunction.

Porcine circovirus type 2 ORF3 protein induces apoptosis in melanoma cells

BACKGROUND

The current treatment of malignant melanoma is limited by the lack of effective therapeutic approaches, and alternative treatments are needed. Proliferative diseases such as melanoma and other cancers may be treatable by virally-encoded apoptotic proteins that are targeted to rapidly multiplying cells. Caspase-dependent apoptosis, that is frequently used in chemotherapy, can boost the cell proliferation that caspase-independent cell death does not.

METHODS

In the current study, the porcine circovirus type 2 (PCV2), proapoptotic protein ORF3 was expressed in mouse and human cancer cell lines, and its apoptotic activity was assessed.

RESULTS

Quantitative assessment of the apoptotic cells by flow cytometry showed that apoptotic cell death was significantly increased in ORF3-expressing malignant cells, compared to ORF3 non-expressing cells. Our data show that PCV2 ORF3 induces apoptosis in a caspase-3 and -8 independent manner. ORF3 expression seems to cause an increase in abnormal mitosis in B16F10 melanoma cells by interacting with centrosomes and thereby disrupting the formation of the mitotic spindle. In addition, we show that ORF3 of PCV2 also exhibits significant anti-tumor effects in vivo. Although the expression of Regulator of G protein Signaling (RGS)-16 by recipient mice inhibited the development of grafted melanoma in vivo, it was not required for the antitumoral activity of ORF3.

CONCLUSION

PCV2 ORF3 causes abnormal mitosis in rapidly dividing cells and increases the apoptosis of cancer cells. Apoptin might, therefore, be considered to develop future antitumoral strategies.

Naringenin has a chemoprotective effect in MDA-MB-231 breast cancer cells via inhibition of caspase-3 and -9 activities

Breast cancer is the leading cause of cancer-associated mortality in females. It has an incidence of 1.3 million per year, which increases by 2% annually. In China, breast cancer accounts for 12.2% of all cancer cases. The aim of the present study was to investigate the inhibitory effect of naringenin on triple-negative breast cancer cells. Lactate dehydrogenase and MTT assay was used to investigate the inhibitory effect of naringenin on MDA-MB-231 cell viability. Naringenin reduced the viability of MDA-MB-231 cells by arresting the cell cycle at the G₂ phase. Naringenin treatment not only influenced the phase of cell cycle arrest, but also induced apoptosis in a dose-dependent manner. Naringenin treatment also resulted in a significant increase in caspase-3 and caspase-9 activity (P<0.001). Taken together, the results of the present study suggested that naringenin caused an inhibitory effect on MDA-MB-231 cells via induction of apoptosis and inhibition of caspase-3 and -9 activity.

Su Yang Decoction induces human colon carcinoma cell apoptosis by activating caspases

Su Yang Decoction (SYD) is a popular healthcare product comprised of various brassicaceous vegetables known to exhibit anticancer activity. However, the effects of SYD on tumor growth, following its combination with brassicaceous vegetables into a compound formula, require further investigation. In the present study, a quality control of SYD was subjected to high-performance liquid chromatography for the quantitative and qualitative determination of sulforaphane, the main anticancer component of SYD. SYD inhibited colon cancer cell proliferation in a dose- and time-dependent manner and induced G1 phase arrest in colon cancer HT-29 cell lines. In addition, SYD triggered caspase-mediated apoptosis in a dose-dependent manner and induced the cleavage of poly (ADP-ribose) polymerase, tumor necrosis factor superfamily member 10, X-linked inhibitor of apoptosis, and truncated BH3 interacting domain death agonist. Furthermore, the expression of FADD-like interleukin-1β-converting enzyme (FLICE)-like inhibitory proteins (FLIPs) and long isoform of FLICE-inhibitory protein was reduced by SYD and the direct targeting of cellular-FLIP with small interfering RNA inhibited colon cancer cell proliferation and decreased the SYD concentration required for proliferation inhibition. SYD treatment was also associated with the translocation of proapoptotic BCL2 associated X, apoptosis regulator to the mitochondria and the release of cytochrome c from the mitochondria to the cytosol. The aforementioned results indicate that SYD exerts anti-colorectal cancer effects through an underlying mechanism that may involve caspase activation.

Synergistic inhibitory effects of capsaicin combined with cisplatin on human osteosarcoma in culture and in xenografts

BACKGROUND

The combination of phytochemicals with chemotherapy drugs is an emerging new strategy for cancer therapy to increase antitumor responses.

METHODS

The present study investigates the effect of the combination of capsaicin (CAP) with cisplatin (DDP) and the potential underlying anticancer mechanisms in osteosarcoma (OS) cells in vitro and in vivo.

RESULTS

Cell viability assays and isobolographic analyses demonstrated that the combination of CAP and DDP showed synergistic cytotoxic effects on OS cells. We chose relatively low concentrations of CAP (100 μM) and DDP (16.7 μM) for subsequent experiments. Generally, the combination of CAP and DDP had significant effects on apoptosis induction, cell cycle arrest and cell invasion inhibition in OS cells compared with the individual-treatment groups and the control group. Moreover, cotreatment with CAP and DDP triggered prosurvival autophagy through reactive oxygen species (ROS)/JNK and p-AKT/mTOR signaling in OS cells. The combination regimen of CAP and DDP also inhibited tumor growth in an OS xenograft model.

CONCLUSION

These results suggest that the combination of CAP and DDP has strong inhibitory effects on OS cells and identify CAP as a promising agent for supplementing standard chemotherapy and possible future targeted therapy in OS.

Non-apoptotic Caspase regulation of stem cell properties

The evolutionarily conserved family of proteins called caspases are the main factors mediating the orchestrated programme of cell suicide known as apoptosis. Since this protein family was associated with this essential biological function, the majority of scientific efforts were focused towards understanding their molecular activation and function during cell death. However, an emerging body of evidence has highlighted a repertoire of non-lethal roles within a large variety of cell types, including stem cells. Here we intend to provide a comprehensive overview of the key role of caspases as regulators of stem cell properties. Finally, we briefly discuss the possible pathological consequences of caspase malfunction in stem cells, and the therapeutic potential of caspase regulation applied to this context.

Sanguinarine suppresses growth and induces apoptosis in childhood acute lymphoblastic leukemia

Sanguinarine (Sang), a plant-derived compound isolated from the roots of Sanguinaria canadensis was evaluated for its potential pro-apoptotic effects in precursor B acute lymphoblastic leukemia (Pre-ALL) cell lines. Treatment of 697, REH, RS4;11, and SupB15 cell lines with Sang exhibited significant inhibition of cell viability via induction of apoptotic cell death. Sang-mediated apoptosis was found to be associated with the increased expression of proapoptotic bax with concomitant decrease of Bcl-2 expression leading to depolarization of mitochondria membrane resulting in loss of mitochondrial membrane potential (MMP). The reduced MMP caused the leakage in mitochondrial membrane and release of cytochrome c into the cytosol. The cytochrome c then mediates the activation of caspase-cascade and subsequently PARP cleavage. Furthermore, pretreatment with z-VAD-FMK, a pan-caspase inhibitor, abrogated Sang-induced inhibition of cell viability, induction of apoptosis. Sang treatment also reduced the phosphorylation of AKT and suppressed the expression of a number of anti-apoptotic genes such as cIAP1, cIAP2, and XIAP. Sang mediates its anti-cancer activity by generation of reactive oxygen species (ROS) due to depletion of glutathione level in leukemic cell lines. Pretreatment of these cells with N-acetyl cysteine (NAC) prevented Sang-induced depletion of glutathione level and mitochondrial-caspase-induced apoptosis. Finally, Sang treatment of Pre-ALL cell suppressed colony formation ability of these cells suggesting Sang has an anti-leukemic potential. Altogether, our data suggest that Sang is an efficient inducer of intrinsic apoptotic cell death via generation of ROS and exhibition of anti-leukemic effect in Pre-ALL cells raises the possibility to develop Sang as a therapeutic modality for the treatment and management of Pre-ALL.