The Wnt Signaling Pathway Inhibitors Improve the Therapeutic Activity of Glycolysis Modulators against Tongue Cancer Cells

Excessive glucose metabolism and disruptions in Wnt signaling are important molecular changes present in oral cancer cells. The aim of this study was to evaluate the effects of the combinatorial use of glycolysis and Wnt signaling inhibitors on viability, cytotoxicity, apoptosis induction, cell cycle distribution and the glycolytic activity of tongue carcinoma cells. CAL 27, SCC-25 and BICR 22 tongue cancer cell lines were used. Cells were treated with inhibitors of glycolysis (2-deoxyglucose and lonidamine) and of Wnt signaling (PRI-724 and IWP-O1). The effects of the compounds on cell viability and cytotoxicity were evaluated with MTS and CellTox Green tests, respectively. Apoptosis was evaluated by MitoPotential Dye staining and cell cycle distribution by staining with propidium iodide, followed by flow cytometric cell analysis. Glucose and lactate concentrations in a culture medium were evaluated luminometrically. Combinations of 2-deoxyglucose and lonidamine with Wnt pathway inhibitors were similarly effective in the impairment of oral cancer cells’ survival. However, the inhibition of the canonical Wnt pathway by PRI-724 was more beneficial, based on the glycolytic activity of the cells. The results point to the therapeutic potential of the combination of low concentrations of glycolytic modulators with Wnt pathway inhibitors in oral cancer cells.     

Hyperthermia Enhances Doxorubicin Therapeutic Efficacy against A375 and MNT-1 Melanoma Cells

Melanoma is the deadliest form of skin cancer, and its incidence has alarmingly increased in the last few decades, creating a need for novel treatment approaches. Thus, we evaluated the combinatorial effect of doxorubicin (DOX) and hyperthermia on A375 and MNT-1 human melanoma cell lines. Cells were treated with DOX for 24, 48, and 72 h and their viabilities were assessed. The effect of DOX IC10 and IC20 (combined at 43 °C for 30, 60, and 120 min) on cell viability was further analyzed. Interference on cell cycle dynamics, reactive oxygen species (ROS) production, and apoptosis upon treatment (with 30 min at 43 °C and DOX at the IC20 for 48 h) were analyzed by flow cytometry. Combined treatment significantly decreased cell viability, but not in all tested conditions, suggesting that the effect depends on the drug concentration and heat treatment duration. Combined treatment also mediated a G2/M phase arrest in both cell lines, as well as increasing ROS levels. Additionally, it induced early apoptosis in MNT-1 cells, while in A375 cells this effect was similar to the one caused by hyperthermia alone. These findings demonstrate that hyperthermia enhances DOX effect through cell cycle arrest, oxidative stress, and apoptotic cell death.     

Arsenic Trioxide Inhibits Cell Growth and Induces Apoptosis through Inactivation of Notch Signaling Pathway in Breast Cancer

Arsenic trioxide has been reported to inhibit cell growth and induce apoptotic cell death in many human cancer cells including breast cancer. However, the precise molecular mechanisms underlying the anti-tumor activity of arsenic trioxide are still largely unknown. In the present study, we assessed the effects of arsenic trioxide on cell viability and apoptosis in breast cancer cells. For mechanistic studies, we used multiple cellular and molecular approaches such as MTT assay, apoptosis ELISA assay, gene transfection, RT-PCR, Western blotting, and invasion assays. For the first time, we found a significant reduction in cell viability in arsenic trioxide-treated cells in a dose-dependent manner, which was consistent with induction of apoptosis and also associated with down-regulation of Notch-1 and its target genes. Taken together, our findings provide evidence showing that the down-regulation of Notch-1 by arsenic trioxide could be an effective approach, to cause down-regulation of Bcl-2, and NF-κB, resulting in the inhibition of cell growth and invasion as well as induction of apoptosis. These results suggest that the anti-tumor activity of arsenic trioxide is in part mediated through a novel mechanism involving inactivation of Notch-1 and its target genes. We also suggest that arsenic trioxide could be further developed as a potential therapeutic agent for the treatment of breast cancer.     

Adipose-Derived Stem Cells Preincubated with Green Tea EGCG Enhance Pancreatic Tissue Regeneration in Rats with Type 1 Diabetes through ROS/Sirt1 Signaling Regulation

Type 1 diabetes stem-cell-based therapy is one of the best therapeutic approaches for pancreatic damage treatment due to stem cell tissue regeneration. Epigallocatechin gallate (EGCG) is one of the active components found in green tea. Experimental results suggest that EGCG shows beneficial effects on cell protection. This study explores whether a better pancreatic regeneration therapeutic effect could be found in mesenchymal stem cells pretreated with EGCG compared to stem cells without EGCG pretreatment. A cell model confirmed that adipose-derived stem cells (ADSC) incubated with EGCG increase cell viability under high-glucose (HG) stress. This is due to survival marker p-Akt expression. In an animal model, type 1 diabetes induced the activation of several pathological signals, including islet size reduction, extracellular fibrotic collagen deposition, oxidative stress elevation, survival pathway suppression, apoptosis signaling induction, and Sirt1 antioxidant pathway downregulation. Ordinary ADSC transplantation slightly improved the above pathological signals. Further, EGCG-pretreated ADSC transplantation significantly improved the above pathological conditions. Taken together, EGCG-pretreated ADSCs show clinical potential in the treatment of patients with type 1 diabetes through the regeneration of damaged pancreatic tissues.     

Novel Bi-Specific Immuno-Modulatory Tribodies Potentiate T Cell Activation and Increase Anti-Tumor Efficacy

Cancer immunotherapy has already shown significant improvements by combining different antibodies specific for distinct immune checkpoints, such as Ipilimumab and Nivolumab. Here, we tested combinatorial treatments of immunomodulatory antibodies, previously generated in our laboratory, for their effects on hPBMC activation, either upon stimulation with SEB or in co-cultures with tumor cells by cytokine secretion assays. We found that some of them showed additive or synergistic effects, and on the basis of these observations, we constructed, for the first time, four novel bispecific tribodies (TR), made up of a Fab derived from one anti-IC mAb and two scFvs derived from another mAb targeting a different IC. All four TRs cotargeting either programmed cell death protein 1 (PD-1) and Lymphocyte Activating 3 (LAG-3) or programmed death-ligand 1 (PD-L1) and LAG-3 retained binding affinity for their targets and the antagonistic effects of their parental mAbs, but some of them also showed an increased ability to induce lymphocyte activation and increased in vitro cytotoxicity against tumor cells compared to parental antibodies used either alone or in combinatorial treatments. Furthermore, none of the tribodies showed significant increased cytotoxicity on human cardiomyocytes. Considering that the tribody format reduces production costs (as only one construct provides the inhibitory effects of two antibodies), has an intermediate molecular size (100 kDa) which is well suited for both tumor penetration and an acceptable half-life, we think that these novel immunomodulatory TRBs have the potential to become precious tools for therapeutic applications, particularly in monotherapy-resistant cancer patients.     

Arachidin-1, a Prenylated Stilbenoid from Peanut,Induces Apoptosis in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is unresponsive to typical hormonal treatments, causing it to be one of the deadliest forms of breast cancer. Investigating alternative therapies to increase survival rates for this disease is essential. The goal of this study was to assess cytotoxicity and apoptosis mechanisms of prenylated stilbenoids in TNBC cells. The prenylated stilbenoids arachidin-1 (A-1) and arachidin-3 (A-3) are analogs of resveratrol (RES) produced in peanut upon biotic stress. The anticancer activity of A-1 and A-3 isolated from peanut hairy root cultures was determined in TNBC cell lines MDA-MB-231 and MDA-MB-436. After 24 h of treatment, A-1 exhibited higher cytotoxicity than A-3 and RES with approximately 11-fold and six-fold lower IC₅₀, respectively, in MDA-MB-231 cells, and nine-fold and eight-fold lower IC₅₀, respectively, in MDA-MB-436 cells. A-1 did not show significant cytotoxicity in the non-cancerous cell line MCF-10A. While A-1 blocked cell division in G2-M phases in the TNBC cells, it did not affect cell division in MCF-10A cells. Furthermore, A-1 induced caspase-dependent apoptosis through the intrinsic pathway by activating caspase-9 and PARP cleavage, and inhibiting survivin. In conclusion, A-1 merits further research as a potential lead molecule for the treatment of TNBC.     

Ruthenium(II)–Arene Thiocarboxylates: Identification of a Stable Dimer Selectively Cytotoxic to Invasive Breast Cancer Cells

Ru^II-arene complexes provide a versatile scaffold for novel anticancer drugs. Seven new Ru^II-arene-thiocarboxylato dimers were synthesized and characterized. Three of the complexes ( 2 a , b and 5 ) showed promising antiproliferative activities in MDA-MB-231 (human invasive breast cancer) cells, and were further tested in a panel of fifteen cancerous and noncancerous cell lines. Complex 5 showed moderate but remarkably selective activity in MDA-MB-231 cells (IC₅₀=39±4 μm Ru). Real-time proliferation studies showed that 5 induced apoptosis in MDA-MB-231 cells but had no effect in A549 (human lung cancer, epithelial) cells. By contrast, 2 a and b showed moderate antiproliferative activity, but no apoptosis, in either cell line. Selective cytotoxicity of 5 in aggressive, mesenchymal-like MDA-MB-231 cells over many common epithelial cancer cell lines (including noninvasive breast cancer MCF-7) makes it an attractive lead compound for the development of specifically antimetastatic Ru complexes with low systemic toxicity.     

Multifunctional Role of Lipids in Modulating the Tumorigenic Properties of 4T1 Breast Cancer Cells

Tumor growth and progression are linked to an altered lipid metabolism in the tumor microenvironment (TME), including tumor cells and tumor-associated macrophages (TAMs). A growing number of lipid metabolism targeting drugs have shown efficacy in anti-tumor therapy. In addition, exogenously applied lipids and lipid analogues have demonstrated anti-tumor activities in several cancers, including breast cancer. In this study, we investigated the anti-tumor efficacies of the natural lipids palmitic acid (PA), sphingomyelin (SM), ceramide (Cer) and docosahexaenoic acid (DHA) on breast cancer cells. All tested lipids reduced the malignancy of breast cancer cells in vitro by impairing cell proliferation, migration and invasiveness. PA showed superior anti-tumor properties, as it additionally impaired cancer cell viability by inducing apoptosis, without affecting healthy cells. Co-culture experiments further demonstrated that Cer and PA reduced the immunosuppressive phenotype of M2 macrophages and the M2 macrophage-promoted the epithelial–mesenchymal transition (EMT) and migration of breast cancer cells. At the molecular level, this coincided with the up-regulation of E-cadherin. Our results highlight a powerful role for exogenously applied PA and Cer in reducing breast cancer tumorigenicity by simultaneously targeting cancer cells and M2 macrophages. Our findings support the notion that lipids represent alternative biocompatible therapeutic agents for breast cancer.     

Inhibition of Autophagy Potentiates Atorvastatin-Induced Apoptotic Cell Death in Human Bladder Cancer Cells in Vitro

Statins are cholesterol reduction agents that exhibit anti-cancer activity in several human cancers. Because autophagy is a crucial survival mechanism for cancer cells under stress conditions, cooperative inhibition of autophagy acts synergistically with other anti-cancer drugs. Thus, this study investigates whether combined treatment of atorvastatin and autophagy inhibitors results in enhancing the cytotoxic effects of atorvastatin, upon human bladder cancer cells, T24 and J82, in vitro. To measure cell viability, we performed the EZ-Cytox cell viability assay. We examined apoptosis by flow cytometry using annexin-V/propidium iodide (PI and western blot using procaspase-3 and poly (ADP-ribose) polymerase (PARP) antibodies. To examine autophagy activation, we evaluated the co-localization of LC3 and LysoTracker by immunocytochemistry, as well as the expression of LC3 and p62/sequestosome-1 (SQSTM1) by western blot. In addition, we assessed the survival and proliferation of T24 and J82 cells by a clonogenic assay. We found that atorvastatin reduced the cell viability of T24 and J82 cells via apoptotic cell death and induced autophagy activation, shown by the co-localization of LC3 and LysoTracker. Moreover, pharmacologic inhibition of autophagy significantly enhanced atorvastatin-induced apoptosis in T24 and J82 cells. In sum, inhibition of autophagy potentiates atorvastatin-induced apoptotic cell death in human bladder cancer cells in vitro, providing a potential therapeutic approach to treat bladder cancer.     

The Impact of [C16Pyr][Amp] on the Aggressiveness in Breast and Prostate Cancer Cell Lines

Breast (BrCa) and prostate (PCa) cancers are the most common malignancies in women and men, respectively. The available therapeutic options for these tumors are still not curative and have severe side effects. Therefore, there is an urgent need for more effective antineoplastic agents. Herein, BrCa, PCa, and benign cell lines were treated with two ionic liquids and two quinoxalines and functional experiments were performed—namely cell viability, apoptosis, cytotoxicity, and colony formation assays. At the molecular level, an array of gene expressions encompassing several molecular pathways were used to explore the impact of treatment on gene expression. Although both quinoxalines and the ionic liquid [C2OHMIM][Amp] did not show any effect on the BrCa and PCa cell lines, [C16Pyr][Amp] significantly decreased cell viability and colony formation ability, while it increased the apoptosis levels of all cell lines. Importantly, [C16Pyr][Amp] was found to be more selective for cancer cells and less toxic than cisplatin. At the molecular level, this ionic liquid was also associated with reduced expression levels of CPT2, LDHA, MCM2, and SKP2, in both BrCa and PCa cell lines. Hence, [C16Pyr][Amp] was shown to be a promising anticancer therapeutic agent for BrCa and PCa cell lines.     

Cytotoxic Activity of LLO Y406A Is Targeted to the Plasma Membrane of Cancer Urothelial Cells

Identification of novel agents for bladder cancer treatment is highly desirable due to the high incidence of tumor recurrence and the risk of progression to muscle-invasive disease. The key feature of the cholesterol-dependent toxin listeriolysin O mutant (LLO Y406A) is its preferential activity at pH 5.7, which could be exploited either directly for selective targeting of cancer cells or the release of accumulated therapeutics from acidic endosomes. Therefore, our goal was to compare the cytotoxic effect of LLO Y406A on cancer cells (RT4) and normal urothelial cells (NPU), and to identify which cell membranes are the primary target of LLO Y406A by viability assays, life-cell imaging, fluorescence, and electron microscopy. LLO Y406A decreased viability, altered cell morphology, provoked membrane blebbing, and induced apoptosis in RT4 cells, while it did not affect NPU cells. LLO Y406A did not cause endosomal escape in RT4 cells, while the plasma membrane of RT4 cells was revealed as the primary target of LLO Y406A. It has been concluded that LLO Y406A has the ability to selectively eliminate cancer urothelial cells through pore-forming activity at the plasma membrane, without cytotoxic effects on normal urothelial cells. This promising selective activity merits further testing as an anti-cancer agent.     

JAK2 Inhibitor,Fedratinib, Inhibits P-gp Activity and Co-Treatment Induces Cytotoxicity in Antimitotic Drug-Treated P-gp Overexpressing Resistant KBV20C Cancer Cells

P-glycoprotein (P-gp) overexpression is one of the major mechanisms of multidrug resistance (MDR). Previously, co-treatment with Janus kinase 2 (JAK2) inhibitors sensitized P-gp-overexpressing drug-resistant cancer cells. In this study, we assessed the cytotoxic effects of JAK2 inhibitor, fedratinib, on drug-resistant KBV20C cancer cells. We found that co-treatment with fedratinib at low doses induced cytotoxicity in KBV20C cells treated with vincristine (VIC). However, fedratinib-induced cytotoxicity was little effect on VIC-treated sensitive KB parent cells, suggesting that these effects are specific to resistant cancer cells. Fluorescence-activated cell sorting (FACS), Western blotting, and annexin V analyses were used to further investigate fedratinib’s mechanism of action in VIC-treated KBV20C cells. We found that fedratinib reduced cell viability, increased G2 arrest, and upregulated apoptosis when used as a co-treatment with VIC. G2 phase arrest and apoptosis in VIC–fedratinib-co-treated cells resulted from the upregulation of p21 and the DNA damaging marker pH2AX. Compared with dimethyl sulfoxide (DMSO)-treated cells, fedratinib-treated KBV20C cells showed two-fold higher P-gp-inhibitory activity, indicating that VIC–fedratinib sensitization is dependent on the activity of fedratinib. Similar to VIC, fedratinib co-treatment with other antimitotic drugs (i.e., eribulin, vinorelbine, and vinblastine) showed increased cytotoxicity in KBV20C cells. Furthermore, VIC–fedratinib had similar cytotoxic effects to co-treatment with other JAK2 inhibitors (i.e., VIC–CEP-33779 or VIC–NVP-BSK805) at the same dose; similar cytotoxic mechanisms (i.e., early apoptosis) were observed between treatments, suggesting that co-treatment with JAK2 inhibitors is generally cytotoxic to P-gp-overexpressing resistant cancer cells. Given that fedratinib is FDA-approved, our findings support its application in the co-treatment of P-gp-overexpressing cancer patients showing MDR.     

The Comparison of the Efficiency of Emodin and Aloe-Emodin in Photodynamic Therapy

Skin cancer (melanoma and non-melanoma) is the most frequent type of malignancy in the Caucasian population. Photodynamic therapy (PDT) as an interesting and unique strategy may potentially boost standard therapeutic approaches. In the present study, the potential of emodin and aloe-emodin as photosensitizers in photodynamic therapy has been investigated. The conducted research presents for the first-time comparison of the phototoxic and anti-cancerous effects of emodin and aloe-emodin on skin cancer cell lines, including SCC-25 representing cutaneous squamous cell carcinoma, MUG-Mel2 representing a melanoma cell line, and normal human keratinocytes HaCaT representing control normal skin cells. To assess the effectiveness of emodin and aloe-emodin as a photosensitizer in PDT on different skin cell lines, we performed MTT assay measuring cytotoxicity of natural compounds, cellular uptake, apoptosis with flow cytometry, and a wound-healing assay. Although emodin and aloe-emodin are isomers and differ only in the position of one hydroxyl group, our phototoxicity and apoptosis detection results show that both substances affect skin cancer cells (SSC-25 squamous cell carcinoma and MUG-Mel2 melanoma) and normal keratinocytes (HaCaT cell line) in other ways. In conclusion, our study provides evidence suggesting that emodin and aloe-emodin mediated PDT exhibits the potential for clinical development as a new effective and safe photosensitizer to treat skin cancer.     

Antimicrobial Properties of Palladium and Platinum Nanoparticles: A New Tool for Combating Food-Borne Pathogens

Although some metallic nanoparticles (NPs) are commonly used in the food processing plants as nanomaterials for food packaging, or as coatings on the food handling equipment, little is known about antimicrobial properties of palladium (PdNPs) and platinum (PtNPs) nanoparticles and their potential use in the food industry. In this study, common food-borne pathogens Salmonella enterica Infantis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus were tested. Both NPs reduced viable cells with the log₁₀ CFU reduction of 0.3–2.4 (PdNPs) and 0.8–2.0 (PtNPs), average inhibitory rates of 55.2–99% for PdNPs and of 83.8–99% for PtNPs. However, both NPs seemed to be less effective for biofilm formation and its reduction. The most effective concentrations were evaluated to be 22.25–44.5 mg/L for PdNPs and 50.5–101 mg/L for PtNPs. Furthermore, the interactions of tested NPs with bacterial cell were visualized by transmission electron microscopy (TEM). TEM visualization confirmed that NPs entered bacteria and caused direct damage of the cell walls, which resulted in bacterial disruption. The in vitro cytotoxicity of individual NPs was determined in primary human renal tubular epithelial cells (HRTECs), human keratinocytes (HaCat), human dermal fibroblasts (HDFs), human epithelial kidney cells (HEK 293), and primary human coronary artery endothelial cells (HCAECs). Due to their antimicrobial properties on bacterial cells and no acute cytotoxicity, both types of NPs could potentially fight food-borne pathogens.     

Systemic Evaluation of Mechanism of Cytotoxicity in Human Colon Cancer HCT-116 Cells of Silver Nanoparticles Synthesized Using Marine Algae Ulva lactuca Extract

In the current study, biogenic silver nanoparticles (U-AgNPs) were synthesized using marine green macro-algal Ulva lactuca extract, and evaluated mechanism behind its anticancer activity against the Human colon cancer (HCT-116). The biogenic U-AgNPs were characterized using various physiochemical techniques. The TEM micrographs confirmed the spherical morphology of synthesized U-AgNPs, with a mean size of 8–14 nm. EDX spectrum as well as ICP-OES confirmed that AgNPs was nearly 90% purity for silver. FTIR Spectra analysis of U-AgNPs confirmed U. lactuca extract bioactive molecules presence over U-AgNPs surface as a stabilizing agent, thereby improving biocompatibility. The cytotoxicity study revealed the dose dependent cell death in colon cancer cells with no loss of viability in normal human colon epithelial cells. Furthermore, the fluorescence micrographs of nucleus staining assay revealed the DNA fragmentation and nucleus condensation of cancer cells treated with U-AgNPs, indicating an apoptosis-mediated cell death. The western bolt and RT-PCR analysis of U-AgNPs treated cancer cells showed the rise in proapoptotic markers (P53, Bax, and P21) and decline in anti-apoptotic markers (Bcl-2), thus confirming the p53-dependent apoptosis mediated cell death in HCT-116. Overall, our study concluded that novel biogenic U-AgNPs nanoparticles, synthesized using marine green macro-algal U. lactuca extract showed efficient anticancer activity against HCT-116 cell line and hence could work as potential therapeutic agent for targeted anti-cancer therapy.

     

曲古抑菌素A与罗格列酮联合应用对胃癌细胞增殖的抑制作用

目的研究组蛋白去乙酰化酶(HDAC)抑制剂曲古抑菌素A(TSA)与过氧化物酶体增殖物激活受体γ配体罗格列酮(ROZ)联合应用对胃癌细胞SGC-7901增殖的抑制作用,并探讨其可能的作用机制。方法首先用不同浓度的TSA和ROZ分别作用于SGC-7901细胞,MTT法检测二者对细胞增殖的抑制作用,以筛选出合适的联合作用浓度。将SGC-7901细胞随机分为对照组、TSA组、ROZ组和TSA+ROZ组,加入相应的药物处理48h后,MTT法检测各组细胞增殖抑制率,并应用流式细胞仪检测细胞周期情况,RT-PCR检测PPARγ和CyclinD1基因mRNA的转录水平。结果对SGC-7901细胞增殖抑制作用不显著的低剂量TSA(40nmol/L)与ROZ联用时,能显著增强ROZ对细胞增殖的抑制作用,TSA+ROZ组G0/G1期细胞比例较单用TSA或ROZ组明显增加,且CyclinD1基因mRNA转录水平明显下降;TSA作用于细胞后,PPARγ基因mRNA转录水平较对照组明显升高,而ROZ单独作用后,细胞PPARγ基因mRNA转录水平无改变。结论TSA可明显增强ROZ对SGC-7901细胞增殖的抑制效应,提示HDAC在SGC-7901细胞内可能具有抑制PPARγ的作用。     

Dextran and Polymer Polyethylene Glycol (PEG) Coating Reduce Both 5 and 30 nm Iron Oxide Nanoparticle Cytotoxicity in 2D and 3D Cell Culture

Superparamagnetic iron oxide nanoparticles are widely used in biomedical applications, yet questions remain regarding the effect of nanoparticle size and coating on nanoparticle cytotoxicity. In this study, porcine aortic endothelial cells were exposed to 5 and 30 nm diameter iron oxide nanoparticles coated with either the polysaccharide, dextran, or the polymer polyethylene glycol (PEG). Nanoparticle uptake, cytotoxicity, reactive oxygen species (ROS) formation, and cell morphology changes were measured. Endothelial cells took up nanoparticles of all sizes and coatings in a dose dependent manner, and intracellular nanoparticles remained clustered in cytoplasmic vacuoles. Bare nanoparticles in both sizes induced a more than 6 fold increase in cell death at the highest concentration (0.5 mg/mL) and led to significant cell elongation, whereas cell viability and morphology remained constant with coated nanoparticles. While bare 30 nm nanoparticles induced significant ROS formation, neither 5 nm nanoparticles (bare or coated) nor 30 nm coated nanoparticles changed ROS levels. Furthermore, nanoparticles were more toxic at lower concentrations when cells were cultured within 3D gels. These results indicate that both dextran and PEG coatings reduce nanoparticle cytotoxicity, however different mechanisms may be important for different size nanoparticles.     

Compound K, a Metabolite of Ginseng Saponin, Induces Mitochondria-Dependent and Caspase-Dependent Apoptosis via the Generation of Reactive Oxygen Species in Human Colon Cancer Cells

The objective of this study was to elucidate the cytotoxic mechanism of Compound K, with respect to the involvement of reactive oxygen species (ROS) and the mitochondrial involved apoptosis, in HT-29 human colon cancer cells. Compound K exhibited a concentration of 50% growth inhibition (IC(50)) at 20 μg/mL and cytotoxicity in a time dependent manner. Compound K produced intracellular ROS in a time dependent fashion; however, N-acetylcysteine (NAC) pretreatment resulted in the inhibition of this effect and the recovery of cell viability. Compound K induced a mitochondria-dependent apoptotic pathway via the modulation of Bax and Bcl-2 expressions, resulting in the disruption of the mitochondrial membrane potential (Δψ(m)). Loss of the Δψ(m) was followed by cytochrome c release from the mitochondria, resulting in the activation of caspase-9, -3, and concomitant poly ADP-ribosyl polymerase (PARP) cleavage, which are the indicators of caspase-dependent apoptosis. The apoptotic effect of Compound K, exerted via the activation of c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), was abrogated by specific MAPK inhibitors. This study demonstrated that Compound K-mediated generation of ROS led to apoptosis through the modulation of a mitochondria-dependent apoptotic pathway and MAPK pathway.     

Cell Survival and Apoptosis Signaling as Therapeutic Target for Cancer: Marine Bioactive Compounds

Inhibition of apoptosis leads to activation of cell survival factors (e.g., AKT) causes continuous cell proliferation in cancer. Apoptosis, the major form of cellular suicide, is central to various physiological processes and the maintenance of homeostasis in multicellular organisms. A number of discoveries have clarified the molecular mechanism of apoptosis, thus clarifying the link between apoptosis and cell survival factors, which has a therapeutic outcome. Induction of apoptosis and inhibition of cell survival by anticancer agents has been shown to correlate with tumor response. Cellular damage induces growth arrest and tumor suppression by inducing apoptosis, necrosis and senescence; the mechanism of cell death depends on the magnitude of DNA damage following exposure to various anticancer agents. Apoptosis is mainly regulated by cell survival and proliferating signaling molecules. As a new therapeutic strategy, alternative types of cell death might be exploited to control and eradicate cancer cells. This review discusses the signaling of apoptosis and cell survival, as well as the potential contribution of marine bioactive compounds, suggesting that new therapeutic strategies might follow.