Encapsulation of Inositol Hexakisphosphate with Chitosan via Gelation to Facilitate Cellular Delivery and Programmed Cell Death in Human Breast Cancer Cells

Inositol hexakisphosphate (InsP6) is the most abundant inositol polyphosphate both in plant and animal cells. Exogenous InsP6 is known to inhibit cell proliferation and induce apoptosis in cancerous cells. However, cellular entry of exogenous InsP6 is hindered due to the presence of highly negative charge on this molecule. Therefore, to enhance the cellular delivery of InsP6 in cancerous cells, InsP6 was encapsulated by chitosan (CS), a natural polysaccharide, via the ionic gelation method. Our hypothesis is that encapsulated InsP6 will enter the cell more efficiently to trigger its apoptotic effects. The incorporation of InsP6 into CS was optimized by varying the ratios of the two and confirmed by InsP6 analysis via polyacrylamide gel electrophoresis (PAGE) and atomic absorption spectrophotometry (AAS). The complex was further characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) for physicochemical changes. The data indicated morphological changes and changes in the spectral properties of the complex upon encapsulation. The encapsulated InsP6 enters human breast cancer MCF-7 cells more efficiently than free InsP6 and triggers apoptosis via a mechanism involving the production of reactive oxygen species (ROS). This work has potential for developing cancer therapeutic applications utilizing natural compounds that are likely to overcome the severe toxic effects associated with synthetic chemotherapeutic drugs.

Co-delivery of oncolytic virus and chemotherapeutic modality: Vincristine against prostate cancer treatment: A potent viro-chemotherapeutic approach

Prostate cancer is a prevalent carcinoma among males, and conventional treatment options are often limited. Cytotoxic chemotherapy, despite its drawbacks, remains a mainstay. We propose a targeted co-delivery approach using nanoscale delivery units for Oncolytic measles virus (OMV) and vincristine (VC) to enhance treatment efficacy. The HA-coated OMV + VC-loaded TCs nanoformulation is designed for targeted oncolytic activity in prostate cancer. The CD44 expression analysis in prostate cancer cell lines indicates a significantly high expression in PC3 cells. The optimization of nanoformulations using Design of Expert (DOE) is performed, and the preparation and characterization of HA-coated OMV + VC-loaded TCs nanoformulations are detailed showing average particle size 397.2 ± 0.01 nm and polydispersity index 0.122 with zeta potential 19.7 + 0.01 mV. Results demonstrate successful encapsulation efficiency with 2.4 × 106 TCID50/Ml and sustained release of OMV and VC from the nanoformulation for up to 72 h. In vitro, assays reveal potent anticancer activity at 10 ± 0.71% cell viability in PC3 cells compared to 73 ± 0.66% in HPrEC and significant morphological changes at 90 µg/ml in dose and time-dependent manner. The co-formulation showed positive cell death 49.5 ± 0.02% at 50 µg PI/ml in PBS and 54.3% cell cycle arrest at the G2/M phase, 8.1% G0/G1 and 5.7% at S phase, with significant mitochondrial membrane potential (MMP) at 50 µg/ml, as assessed by flow cytometry (FACS). The surface-integrating ligand approach enhances the targeted delivery of the oncolytic virus and chemotherapeutic drug, presenting a potential alternative for prostate cancer treatment and suggested that co-administering VC and OMV in a nanoformulation could improve therapeutic outcomes while reducing chemotherapeutic drug doses.

Recent advances in hepatocellular carcinoma-targeted nanoparticles

In the field of medicine, we often brave the unknown like interstellar explorers, especially when confronting the formidable opponent of hepatocellular carcinoma (HCC). The global burden of HCC remains significant, with suboptimal treatment outcomes necessitating the urgent development of novel drugs and treatments. While various treatments for liver cancer, such as immunotherapy and targeted therapy, have emerged in recent years, improving their transport and therapeutic efficiency, controlling their targeting and release, and mitigating their adverse effects remains challenging. However, just as we grope through the darkness, a glimmer of light emerges-nanotechnology. Recently, nanotechnology has attracted attention because it can increase the local drug concentration in tumors, reduce systemic toxicity, and has the potential to enhance the effectiveness of precision therapy for HCC. However, there are also some challenges hindering the clinical translation of drug-loaded nanoparticles (NPs). Just as interstellar explorers must overcome interstellar dust, we too must overcome various obstacles. In future researches, the design and development of nanodelivery systems for novel drugs treating HCC should be the first attention. Moreover, researchers should focus on the active targeting design of various NPs. The combination of the interventional therapies and drug-loaded NPs will greatly advance the process of precision HCC therapy.

Transferrin-inspired iron delivery across the cell membrane using [(L2Fe)2(μ-O)] (L = chlorquinaldol) to harness anticancer activity of ferroptosis

Although iron is a bio-essential metal, dysregulated iron acquisition and metabolism result in production of reactive oxygen species (ROS) due to the Fenton catalytic reaction, which activates ferroptotic cell death pathways. The lipophilic Fe(III)-chelator chlorquinaldol (L; i.e., 5,7-dichloro-8-hydroxy-2-methylquinoline) strongly favors the formation of a highly stable binuclear Fe(III) complex [(L2Fe)2(μ-O)] (1) that can mimic the function of the Fe(III)-transferrin complex in terms of the strong binding to Fe(III) and facile release of Fe(II) when the metal center is reduced. It should be noted that the cellular uptake of 1 is not transferrin receptor-mediated but enhanced by the high lipophilicity of chlorquinaldol. Once 1 is transported across the cell membrane, Fe(III) can be reduced by ferric reductase or other cellular antioxidants to be released as Fe(II), which triggers the Fenton catalytic reaction, thus harnessing the anticancer activity of iron. As the result, this transferrin-inspired iron-delivery strategy significantly reduces the cytotoxicity of 1 in normal human embryonic kidney cells (HEK 293) and the hemolytic activity of 1 in human red blood cells (hRBCs), giving rise to the unique tumor-specific anticancer activity of this Fe(III) complex.

Lipophilic Fe(III)-Complex with Potent Broad-Spectrum Anticancer Activity and Ability to Overcome Pt Resistance in A2780cis Cancer Cells

Although iron is essential for all forms of life, it is also potentially toxic to cells as the increased and unregulated iron uptake can catalyze the Fenton reaction to produce reactive oxygen species (ROS), leading to lipid peroxidation of membranes, oxidation of proteins, cleavage of DNA and even activation of apoptotic cell death pathways. We demonstrate that Fe(hinok)₃ (hinok = 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), a neutral Fe(III) complex with high lipophilicity is capable of bypassing the regulation of iron trafficking to disrupt cellular iron homeostasis; thus, harnessing remarkable anticancer activity against a panel of five different cell lines, including Pt-sensitive ovarian cancer cells (A2780; IC₅₀ = 2.05 ± 0.90 μM or 1.20 μg/mL), Pt-resistant ovarian cancer cells (A2780cis; IC₅₀ = 0.92 ± 0.73 μM or 0.50 μg/mL), ovarian cancer cells (SKOV-3; IC₅₀ = 1.23 ± 0.01 μM or 0.67 μg/mL), breast cancer cells (MDA-MB-231; IC₅₀ = 3.83 ± 0.12 μM or 2.0 μg/mL) and lung cancer cells (A549; IC₅₀ = 1.50 ± 0.32 μM or 0.82 μg/mL). Of great significance is that Fe(hinok)₃ exhibits unusual selectivity toward the normal HEK293 cells and the ability to overcome the Pt resistance in the Pt-resistant mutant ovarian cancer cells of A2780cis.

Pyrazole derivatives of pyridine and naphthyridine as proapoptotic agents in cervical and breast cancer cells

Cancer is one of the leading causes of death worldwide. The increasing prevalence and resistance to chemotherapy is responsible for driving the search of novel molecules to combat this disease. In search of novel compounds with pro-apoptotic potential, pyrazolo-pyridine and pyrazolo-naphthyridine derivatives were investigated against cervical cancer (HeLa) and breast cancer (MCF-7) cells. The anti-proliferative activity was determined through the MTT assay. Potent compounds were then analyzed for their cytotoxic and apoptotic activity through a lactate dehydrogenase assay and fluorescence microscopy after propidium iodide and DAPI staining. Flow cytometry was used to determine cell cycle arrest in treated cells and pro-apoptotic effect was verified through measurement of mitochondrial membrane potential and activation of caspases. Compounds 5j and 5k were found to be most active against HeLa and MCF-7 cells, respectively. G0/G1 cell cycle arrest was observed in treated cancer cells. Morphological features of apoptosis were also confirmed, and an increased oxidative stress indicated the involvement of reactive oxygen species in apoptosis. The compound-DNA interaction studies demonstrated an intercalative mode of binding and the comet assay confirmed the DNA damaging effects. Finally, potent compounds demonstrated a decrease in mitochondrial membrane potential and increased levels of activated caspase-9 and -3/7 confirmed the induction of apoptosis in treated HeLa and MCF-7 cells. The present work concludes that the active compounds 5j and 5k may be used as lead candidates for the development of lead drug molecules against cervical and breast cancer.

Structural elucidation of a Mn(III) derivative anchored with a tetradentate Schiff base precursor: in vitro cytotoxicity study

A new mononuclear Mn(III) derivative, [Mn(L)(H2O)2]ClO4 (1) was obtained by reacting manganese perchlorate with the tetradentate Schiff base precursor, H2L, [where H2L=C6H3(OMe)(OH)CH=N(CH2)3N=CH(OH)(OMe)C6H3] and characterized by various spectral techniques. Single crystal X-ray diffraction analysis revealed that in 1, the central Mn atom is hexa-coordinated via the NNOO donor sites of the Schiff base precursor and two water molecules, yielding a distorted octahedral geometry. Also, the EPR spectra of 1 were recorded at the solid state by varying the temperature (from 90 to 300 K) as well as in different organic solvents; DMSO, MeOH and a mixture CH2Cl2/toluene; the results obtained agree with the geometrical environment around the metal. The cytotoxic activity of the Mn(III) derivative was evaluated against normal and cancer cell lines. The derivative exhibited comparatively better cytotoxic activity against MCF-7 cells compared to SiHa and fibroblast cells.

The characterization and expression analysis under stress conditions of PCST1 in Arabidopsis

Analysis of PCST1 expression characteristics and the role of PCST1 in response to osmotic stress in Arabidopsis thaliana. The structure of PCST1 was analyzed using Bioinformatics method. Real-time PCR, GUS tissue localization and subcellular localization were adopted to analyze the expression pattern of PCST1 in Arabidopsis. To validate the transgenic positive strain of PCST1 using Real-time PCR, overexpression experiments were performed in wild type. Full-length cDNA was cloned and connected into a binary vector with 35S promoter, and the construction was transformed into wild type. With NaCl and mannitol treatments, the germination rate, green leaves rate, physiological indexes were carried out and counted in Arabidopsis with overexpression of PCST1 and T-DNA insertion mutants. The molecular mechanism of PCST1 in response to osmotic stress in Arabidopsis was analyzed. Based on the bioinformatic analysis, PCST1 is a hydrophobin with 403 amino acids, and the molecular weight is 45.3236 KDa. It contains only the START (the lipid/sterol - binding StAR - related lipid transfer protein domains) conservative domain. PCST1 possesses phosphatidylcholine binding sites and transmembrane region. Expression pattern analysis showed that expression of PCST1 increased with time. The PCST1 widely expressed in Arabidopsis, including roots, axils of stem leaves, flowers (sepal, conductive tissue of the petal, thrum, anther and stigmas), and the top and basal parts of the siliquas. It mainly localized in cell membrane. The overexpression of PCST1 enhanced the sensitivity to osmotic stress in Arabidopsis based on the germination rate. While expression of PCST1 decreased, and the sensitivity to osmotic stress had no obvious change in Arabidopsis. Its molecular mechanism study showed, that PCST1 response to osmotic stress resistance by regulating the proline, betaine synthesis, as well as the expression of key genes SOS, NCED, CIPK. PCST1 is composed of 403 amino acids. The START conservative domain, a transmembrane structure, the phosphatidyl choline binding sites are contained in PCST1. It is localized in cytoplasmic membrane. The PCST1 widely expressed in the root, leaf, flower and siliquas. NaCl and mannitol suppressed the expression of PCST1 and PCST1 can negatively control action of Arabidopsis in the osmotic stress. PCST1 regulates the synthetic pathway of proline, betaine and the expression of SOS, NCED and CIPK in response to the osmotic stress resistance.

Manganese Schiff Base Complexes, Crystallographic Studies, Anticancer Activities, and Molecular Docking

Choice of ligands is significant to successful synthesis of metal complexes (coordination compounds). This study reports the use of Schiff base as the right ligand to control the poor bioavailability and neurodegenerative toxicity challenges of manganese ion. In line with this study, document analysis was used as the methodological approach to evaluate the significance of Schiff base ligands in easing these manganese’s challenges and aligning the resultant coordination compounds (manganese Schiff base complexes) as therapeutic agents in anticancer studies. Report also involves crystallographic studies where single crystal X-ray crystallography was used as a chemical characterization technique. In addition, molecular docking studies, MOE2008, and AutoDock software were used to reveal the mode of interaction between the Schiff base and the manganese(II) and (III) ions, as well as scrutinizing the biological efficacy of the manganese(II) and manganese(III) Schiff bases coordination compounds as anticancer agents against some anticancer cell lines. Conclusion drawn was that manganese(II) and manganese(III) Schiff bases coordination compounds gave more active and potent activities than the corresponding Schiff bases. As a result, challenges of neurodegenerative toxicity and poor bioavailability of manganese ion were overcome, and the chelation therapy was fulfilled. Results from single crystal X-ray crystallography confirmed the successful synthesis of manganese(II) and manganese(III) Schiff bases coordination compounds and revealed the mechanism of reaction, while the molecular docking buttressed the biological activities of the Schiff base ligand and manganese Schiff base coordination compounds by portraying the structure activity relationship (SAR) between either Schiff base or the manganese Schiff base coordination compounds and the virtual cancer cell line (receptor protein), where hits were obtained for lead optimizations.

Ameliorative potential of manganese nanoparticles with low-level ionizing radiation against experimentally induced hepatocarcinogenesis

Nanotechnology is a rich field with infinite possibilities of drug designs for cancer treatment. We aimed to biosynthesize manganese nanoparticles (Mn NPs) using Lactobacillus helveticus to investigate its anticancer synergistic effect with low-dose gamma radiation on HCC-induced rats. Diethylnitrosamine (DEN) (20 mg/kg BW, 5 times a week for 6 weeks) induced HCC in rats. Rats received Mn NPs (5 mg/kg BW/day) by gastric gavage over 4 weeks concomitant with single dose of gamma radiation (γ-R) (0.25 Gy). Characterization, cytotoxicity, and anticancer activity of Mn NPs were evaluated. DEN-induced significant liver dysfunction (alanine transaminase activity ALT, total proteins, and albumin levels) associated with significant increase in lipid peroxidation levels with reduction in super oxide dismutase activity. Furthermore, DEN intoxication is sponsored for remarkable increase in levels of Alfa-fetoprotein, tumor necrosis factor α, vascular endothelial growth factor, and transforming growth factor beta with remarkable decrease in caspase 3 and cytochrome c. Treatment with Mn NPs (4.98-11.58 nm) and single dose gamma radiation evoked significant repair in ALT, total protein, and albumin accompanied with balanced oxidative status, diminished inflammatory biomarkers, angiogenic factor, and growth factor with restoration in apoptotic factors. Mn NPs revealed obvious in vitro cytotoxic activity against HepG2 cell line in a dose-dependent manner. Our findings were well appreciated with the histopathological study. In conclusion, a new approach of the single or combined use of Mn NPs with low-dose γ-radiation regimens as promising paradigm for HCC treatment is recommended.

Evaluation of the antitumor activity of a series of the pincer-type metallocomplexes produced from isonicotinohydrazide derivative

In this work we report on the antitumor properties of a series of pincer-type metallocomplexes [Hg₂(HL-keto)Cl₄]_n (1), [Hg(HL-keto)I₂] (2) and [Mn(HL-zwitterion)Cl₂]∙MeOH (3∙MeOH), derived from N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and corresponding metal salts. The Hg(II) and Mn(II) salts are chelated by the keto (HL-keto) or zwitterionic (HL-zwitterion) form of HL, respectively. The cytotoxic effects of these compounds have been accessed against lung adenocarcinoma (A549) and hepatocellular carcinoma (HepG2 and Huh7) cell lines. Complexes 1 and 2 were found to be most efficient against the cell line Huh7 with IC₅₀ value of 2.56 and 9.90 μM, respectively, while they exhibit moderate activity towards cell lines A549 and HepG2, as evidenced from IC₅₀ values in the range 27.98-56.99 μM. Complex 3∙MeOH is less efficient towards all the three cell lines with relatively high IC₅₀ values. The mechanisms of the metallocomplexes killing the aforementioned cells were elucidated by flow cytometry, colony formation and polymerase chain reaction (PCR) analysis of apoptosis related expression of the genes. The results of the cytotoxic effects and antitumor activity on different cell lines are affected by the metal nature and the presence of the coordinated halide.

New Hybrid Scaffolds Based on Carbazole-Chalcones as Potent Anticancer Agents

BACKGROUND AND OBJECTIVES

Despite various technological advances for the treatment of cancer, the identification of new chemical entities with potent anticancer effects remain an indispensable requirement of the time due to multi-drug resistance exhibited by previously developed anticancer drugs. Particularly, the hybrid drugs incorporating two individual bioactive pharmacophores present medicinally important structural leads, thus improving the pharmacodynamic profile of the drug molecules. The antiproliferative and pro-apoptotic activity of the carbazole-chalcone hybrids on human breast and cervical cancer cells will be examined.

MATERIALS AND METHODS

To overcome such complications, in the current study, we evaluated the cytotoxic effects of carbazole-chalcone hybrids on human breast adenocarcinoma (MCF-7), cervical adenocarcinoma (HeLa) cells and normal cells, i.e., Baby Hamster Kidney cells (BHK-21) using MTT (dimethyl-2-thiazolyl-2,5- diphenyl-2H-tetrazolium bromide) assay. The mechanistic studies were performed on potent compound 4g by fluorescent microscopic studies, release of Lactate Dehydrogenase (LDH) and mitochondrial membrane potential, activation of caspase-9 and -3 and flow cytometric analysis.

RESULTS

As revealed by MTT assay, compound 4g was identified as the most potent derivative among the tested series with IC₅₀ values of 5.64 and 29.15μM against HeLa and MCF-7 cells, respectively. The results were compared with cisplatin. Fluorescent microscopic studies using 4',6-diamidino-2-phenylindole (DAPI) and Propidium Iodide (PI) staining confirmed the occurrence of apoptosis in HeLa cells treated with the most active compound 4g. Moreover, compound 4g also triggered the release of Lactate Dehydrogenase (LDH) in treated HeLa and MCF-7 cells while a fluorescence assay displayed a remarkable increase in the activity of caspase-9 and -3. Moreover, flow cytometric results revealed that compound 4g caused G₀/G₁ arrest in the treated HeLa cells.

CONCLUSION

Our results demonstrated that the compound 4g possesses chemotherapeutic properties against breast cancer and cervical adenocarcinoma cells, thus warranting further research to test the anticancer potential of this compound at preclinical and clinical level.

In Vitro Anticancer Effects of Stilbene Derivatives: Mechanistic Studies on HeLa and MCF-7 Cells

BACKGROUND AND OBJECTIVE

The growing prevalence of cancer and the resulting chemoresistance exert a huge burden on healthcare systems and impose a great challenge to public health around the world. In efforts to develop new chemotherapeutic agents for cancer treatment, a class of heterocyclic compounds i.e. triazine-based molecules were investigated as anticancer agents.

MATERIALS AND METHODS

New triazine hybrids of stilbene were synthesized and evaluated as anticancer agents for cervical (HeLa) and breast (MCF-7) carcinoma cells. The compound (7e), sodium (E)-6,6'-(ethene-1,2- diyl)bis(3-((4-chloro-6-((3-luorophenyl)amino)-1,3,5-triazin-2-yl)amino)benzenesulfonate) was found to be most potent among synthesized derivatives and was explored further for detailed mechanistic studies.

RESULTS

In a set comprised of twelve derivatives, compound 7e, sodium (E)-6,6'-(ethene-1,2-diyl)bis(3-((4- chloro-6-((3-luorophenyl)amino)-1,3,5-triazin-2-yl)amino)benzenesulfonate) was found most potent inhibitor for HeLa and MCF-7 cells.

DISCUSSION

The present study has revealed that compound 7e may activate mitochondrial pathway of apoptosis in HeLa and MCF-7 cells which was assessed by DNA binding studies, estimation of the release of Lactate Dehydrogenase (LDH), fluorescence imaging, production of Reactive Oxygen Species (ROS) in cancer cells, analysis of cell cycle by flow cytometry, change in Mitochondrial Membrane Potential (MMP) and activation of caspase-9 and caspase-3.

CONCLUSION

Compound 7e may serve as a lead in designing new anticancer compounds based on stilbene scaffold.

New triorganotin(iv) compounds with aromatic carboxylate ligands: synthesis and evaluation of the pro-apoptotic mechanism

Three new organotin(iv) carboxylate compounds were synthesized and structurally characterized by elemental analysis and FT-IR and multinuclear NMR (1H, 13C, 119Sn) spectroscopy. Single X-ray crystallography reveals that compound C2 has a monoclinic crystal system with space group P21/c having distorted bipyramidal geometry defined by C3SnO2. The synthesized compounds were screened for drug-DNA interactions via UV-Vis spectroscopy and cyclic voltammetry showing good activity with high binding constants. Theoretical investigations also support the reactivity of the compounds as depicted from natural bond orbital (NBO) analysis using Gaussian 09. Synthesized compounds were initially evaluated on two cancer (HeLa and MCF-7) cell lines and cytotoxicity to normal cells was evaluated using a non-cancerous (BHK-21) cell line. All the compounds were found to be active, with IC50 values less than that of the standard drug i.e. cisplatin. The cytotoxic effect of the most potent compound C2 was confirmed by LDH cytotoxicity assay and fluorescence imaging after PI staining. Apoptotic features in compound C2 treated cancer cells were visualized after DAPI staining while regulation of apoptosis was observed by reactive oxygen species generation, binding of C2 with DNA, a change in mitochondrial membrane potential and expression of activated caspase-9 and caspase-3 in cancer cells. Results are indicative of activation of the intrinsic pathway of apoptosis in C2 treated cancer cells.

Effect of manganese, zinc, and copper on the biological and osteogenic properties of mesoporous bioactive glass nanoparticles

Mesoporous bioactive glass nanoparticles (MBGNs) have demonstrated promising properties for the local delivery of therapeutically active ions with the aim to improve their osteogenic properties. Manganese (Mn), zinc (Zn), and copper (Cu) ions have already shown promising pro-osteogenic properties. Therefore, the concentration-dependent impact of MBGNs (composition in mol%: 70 SiO₂ , 30 CaO) and MBGNs containing 5 mol% of either Mn, Zn, or Cu (composition in mol%: 70 SiO₂ , 25 CaO, 5 MnO/ZnO/CuO) on the viability and osteogenic differentiation of human marrow-derived mesenchymal stromal cells (BMSCs) was assessed in this study. Mn-doped MBGNs (5Mn-MBGNs) showed a small "therapeutic window" with a dose-dependent negative impact on cell viability but increasing pro-osteogenic features alongside increasing Mn concentrations. Due to a constant release of Zn, 5Zn-MBGNs showed good cytocompatibility and upregulated the expression of genes encoding for relevant members of the osseous extracellular matrix during the later stages of cultivation. In contrast to all other groups, BMSC viability increased with increasing concentration of Cu-doped MBGNs (5Cu-MBGNs). Furthermore, 5Cu-MBGNs induced an increase in alkaline phosphatase activity. In conclusion, doping with Mn, Zn, or Cu can enhance the biological properties of MBGNs in different ways for their potential use in bone regeneration approaches.

Non-immunological toxicological mechanisms of metamizole-associated neutropenia in HL60 cells

Metamizole is an analgesic and antipyretic, but can cause neutropenia and agranulocytosis. We investigated the toxicity of the metabolites N-methyl-4-aminoantipyrine (MAA), 4-aminoantipyrine (AA), N-formyl-4-aminoantipyrine (FAA) and N-acetyl-4-aminoantipyrine (AAA) on neutrophil granulocytes and on HL60 cells (granulocyte precursor cell line). MAA, FAA, AA, and AAA (up to 100 µM) alone were not toxic for HL60 cells or granulocytes. In the presence of the myeloperoxidase substrate H₂O₂, MAA reduced cytotoxicity for HL60 cells at low concentrations (<50 µM), but increased cytotoxicity at 100 µM H₂O₂. Neutrophil granulocytes were resistant to H₂O₂ and MAA. Fe²⁺ and Fe³⁺ were not toxic to HL60 cells, irrespective of the presence of H₂O₂ and MAA. Similarly, MAA did not increase the toxicity of lactoferrin, hemoglobin or methemoglobin for HL60 cells. Hemin (hemoglobin degradation product containing a porphyrin ring and Fe³⁺) was toxic on HL60 cells and cytotoxicity was increased by MAA. EDTA, N-acetylcystein and glutathione prevented the toxicity of hemin and hemin/MAA. The absorption spectrum of hemin changed concentration-dependently after addition of MAA, suggesting an interaction between Fe³⁺ and MAA. NMR revealed the formation of a stable MAA reaction product with a reaction pathway involving the formation of an electrophilic intermediate. In conclusion, MAA, the principle metabolite of metamizole, increased cytotoxicity of hemin by a reaction involving the formation of an electrophilic metabolite. Accordingly, cytotoxicity of MAA/hemin could be prevented by the iron chelator EDTA and by the electron donors NAC and glutathione. Situations with increased production of hemin may represent a risk factor for metamizole-associated granulocytopenia.

Fabrication and characterization of hydroxypropyl guar-poly (vinyl alcohol)-nano hydroxyapatite composite hydrogels for bone tissue engineering

Biocompatible bone implants composed of natural materials are highly desirable in orthopedic reconstruction procedures. In this study, novel and ecofriendly bionanocomposite hydrogels were synthesized using a blend of hydroxypropyl guar (HPG), poly vinyl alcohol (PVA), and nano-hydroxyapatite (n-HA) under freeze-thaw and mild reaction conditions. The hydrogel materials were characterized using various techniques. TGA studies indicate that both composites, HPG/PVA and HPG/PVA/n-HA, have higher thermal stability compared to HPG alone whereas HPG/PVA/n-HA shows higher stability compared to PVA alone. The HPG/PVA hydrogel shows porous morphology as revealed by the SEM, which is suitable for bone tissue regeneration. Additionally, the hydrogels were found to be transparent and flexible in nature. In vitro biomineralization study performed in simulated body fluid shows HPG/PVA/n-HA has an apatite like structure. The hydrogel materials were employed as extracellular matrices for biocompatibility studies. In vitro cell viability studies using mouse osteoblast MC3T3 cells were performed by MTT, Trypan blue exclusion, and ethidium bromide/acridine orange staining methods. The cell viability studies reveal that composite materials support cell growth and do not show any signs of cytotoxicity compared to pristine PVA. Osteoblastic activity was confirmed by an increased alkaline phosphatase enzyme activity in MC3T3 bone cells grown on composite hydrogel matrices.

Metabolic reprogramming by Dichloroacetic acid potentiates photodynamic therapy of human breast adenocarcinoma MCF-7 cells

Aberrant glycolytic metabolism is one of the hallmarks of carcinogenesis and therefore reversal of metabolic transformation is a promising drug target in cancer treatment strategies. Dichloroacetic acid (DCA) is known to target the glycolytic pathway in cancer cells and facilitates reversal of metabolic transformation from aerobic cytosolic accumulation of pyruvic acid, "the Warburg effect", to mitochondrial oxidative phosphorylation. Recently, combination therapy particularly involving photodynamic therapy (PDT) has received considerable attention in oncology. We hypothesized that if DCA and PDT are combined, they might potentiate mitochondrial dysfunction and induce apoptosis by a reactive oxygen species (ROS) dependent pathway. We used MCF-7 cells as our in vitro model and 5-aminolevulinic acid (5-ALA) dependent PDT therapy to test our hypothesis. We found that combinatorial treatment of MCF-7 cells with PDT and DCA not only increased cell growth inhibition, but also affected mitochondrial membrane integrity perhaps via production of ROS, and enhanced apoptosis. Further, our results on ATP release during the combined treatment demonstrate that immunogenic cell death (ICD) is likely to be a potential mechanism by which PDT and DCA induce cancer cell death. Taken together, our study suggests a novel way of sensitizing MCF-7 cells for accelerated induction of apoptosis and ICD in these cells. The findings included in this study might have direct relevance in breast cancer treatment strategies.

Role of inositol polyphosphates in programed cell death in Dictyostelium discoideum and its developmental life cycle

Programed cell death or apoptosis is a key developmental process that maintains tissue homeostasis in multicellular organisms. Inositol polyphosphates (InsPs) are key signaling molecules known to regulate a variety of cellular processes including apoptosis in such organisms. The signaling role of InsPs in unicellular organisms such as Dictyostelium discoideum (D. discoideum) is not well understood. We investigated whether InsPs also play any role in apoptosis in D. discoideum and whether InsPs-mediated apoptosis follows a mechanism similar to that present in higher multicellular eukaryotes. We measured known apoptotic markers in response to exogenously administered InsP₆, the major InsPs in the cell. We found that InsP₆ was able to cause cell death in D. discoideum cell culture in a dose- and time-dependent manner as determined by cytotoxicity assays. Fluorescence staining with acridine orange/ethidium bromide and flow cytometry results confirmed that the cell death in D. discoideum by InsP₆ was due to apoptotic changes. Poly(ADP-ribose) expression, a known apoptotic marker used in D. discoideum, was also increased following InsP₆ treatment suggesting a role for InsP₆-mediated apoptosis in this organism. InsP₆-mediated cell death was accompanied by production of reactive oxygen species and a decrease in mitochondrial membrane potential. Additionally, we studied the effects of InsP₆ on the developmental life cycle of D. discoideum, the process likely affected by apoptosis. In conclusion, our studies provide evidence that InsP₆-mediated cell death process is conserved in D. discoideum and plays an important signaling role in its developmental life cycle.

Structurally related hydrazone-based metal complexes with different antitumor activities variably induce apoptotic cell death

Three new metal complexes bearing a tridentate hydrazone-based ligand were synthesized and structurally characterized. Depending on the metal ion, the complexes show remarkably different antitumor activities.