Anti-cancer drug-mediated increase in mitochondrial mass limits the application of metabolic viability-based MTT assay in cytotoxicity screening.

The high-throughput metabolic viability-based colorimetric MTT test is commonly employed to screen the cytotoxicity of different chemotherapeutic drugs. The assay assumes a cell density-dependent linear correlation with the MTT spectral absorbance. Therefore, the present study aimed to compare the cytotoxicity assessment between the MTT assay and gold standard cell number enumeration. The cytotoxicity was induced by Cisplatin, Etoposide, and Doxorubicin in human lung epithelial adenocarcinoma cells (A549) and cervix carcinoma (HeLa) cell lines. The mitochondrial mass was estimated, and immunoblotting of succinate dehydrogenase (SDH-A) was performed following drug treatment in both cell lines. Student's t-test paired analysis was employed to calculate the significance of the results, where the value p < 0.05 was considered statistically significant. The drug-induced cytotoxic response estimated by MTT absorbance did not show any significant difference with respect to control, and no correlation was observed with the enumerated cell number in both A549 and HeLa cells. Interestingly, per-cell metabolic viability was found to be increased by 1.18 to 3.26-fold (p < 0.05) following drug treatment. Further, mechanistic investigation revealed a drug concentration-dependent significant increase in mitochondrial mass (1.21 to 4.2-fold) and upregulation of SDH protein (50-70%) as well as enzymatic activity with respect to control in both A549 and Hela cells. The limitation of the MTT assay for drug-induced cytotoxicity assessment is due to increased mitochondrial mass and SDH upregulation in surviving cells, leading to enhanced formazan formation. This leads to a lack of correlation between cell number and MTT spectral absorbance, suggesting that the MTT assay may provide an erroneous conclusion for cytotoxicity assessment.

Granular Hemostatic Composite of Alginate, Calcium, and Zinc for Rapid and Effective Management of Post-Traumatic Hemorrhage.

Post-traumatic hemorrhage, which can result from accidents or battlefield injuries, is a significant global concern due to the high prehospital mortality rate. Substantial efforts have been made to develop hemostatic agents that can effectively reduce hemorrhage in the immediate aftermath of a traumatic event. The present study investigated the potential efficacy of Ca2+ and Zn2+ supplemented sodium alginate-based dry hemostatic particles (SA-CZ DHP) to manage excessive blood loss or post-traumatic hemorrhage. SA-CZ DHP were developed, followed by their physical and biochemical characterization, cytocompatibility and hemocompatibility testing, and critical evaluation of the hemostatic potential in vitro and in vivo. The safe SA-CZ DHP showed high absorption and accelerated blood clotting kinetics with reduced coagulation time (≈70%, p < 0.0001) in whole human blood, observed with insignificant hemolysis and uninterrupted RBC morphology. SA-CZ DHP significantly reduced the mean blood loss (≈90% in SD rats tail incision), and bleeding time (≈60% in BALB/c mice tail incision) was at par with commercially available Celox hemostatic granules. In conclusion, the biocompatible SA-CZ DHP exhibited rapid and effective management of excessive blood loss. It is also pertinent to note that the developed formulation could be a cost-effective alternative to its commercial counterparts.

Nanoemulsion potentiates the anti-cancer activity of Myricetin by effective inhibition of PI3K/AKT/mTOR pathway in triple-negative breast cancer cells.

Triple-negative breast cancer (TNBC) is a heterogeneous tumor with a poor prognosis and high metastatic potential, resulting in poor clinical outcomes, necessitating investigation to devise effective therapeutic strategies. Multiple studies have substantiated the anti-cancer properties of the naturally occurring flavonoid "Myricetin" in various malignancies. However, the therapeutic application of Myricetin is impeded by its poor water solubility and low oral bioavailability. To overcome this limitation, we aimed to develop nanoemulsion of Myricetin (Myr-NE) and evaluate its advantage over Myricetin alone in TNBC cells. The nanoemulsion was formulated using Capryol 90 (oil), Tween 20 (surfactant), and Transcutol HP (co-surfactant). The optimized nano-formulation underwent an evaluation to determine its size, zeta potential, morphology, stability, drug encapsulation efficiency, and in vitro release properties. The anti-cancer activity of Myr-NE was further studied to examine its distinct impact on intracellular drug uptake, cell-viability, anti-tumor signaling, oxidative stress, clonogenicity, and cell death, compared with Myricetin alone in MDA-MB-231 (TNBC) cells. The in vitro drug release and intracellular drug uptake of Myricetin was significantly increased in Myr-NE formulation as compared to Myricetin alone. Moreover, Myr-NE exhibited significant inhibition of cell proliferation, clonogenicity, and increased apoptosis with ~ 2.5-fold lower IC50 as compared to Myricetin. Mechanistic investigation revealed that nanoemulsion augmented the anti-cancer efficacy of Myricetin, most likely by inhibiting the PI3K/AKT/mTOR pathway, eventually leading to enhanced cell death in TNBC cells. The study provides substantial experimental evidence to support the notion that the Myr-NE formulation has the potential to be an effective therapeutic drug for TNBC treatment.

A calcium and zinc composite alginate hydrogel for pre-hospital hemostasis and wound care.

We developed, characterized, and examined the hemostatic potential of sodium alginate-based Ca2+ and Zn2+ composite hydrogel (SA-CZ). SA-CZ hydrogel showed substantial in-vitro efficacy, as observed by the significant reduction in coagulation time with better blood coagulation index (BCI) and no evident hemolysis in human blood. SA-CZ significantly reduced bleeding time (≈60 %) and mean blood loss (≈65 %) in the tail bleeding and liver incision in the mice hemorrhage model (p ≤ 0.001). SA-CZ also showed enhanced cellular migration (1.58-fold) in-vitro and improved wound closure (≈70 %) as compared with betadine (≈38 %) and saline (≈34 %) at the 7th-day post-wound creation in-vivo (p < 0.005). Subcutaneous implantation and intra-venous gamma-scintigraphy of hydrogel revealed ample body clearance and non-considerable accumulation in any vital organ, proving its non-thromboembolic nature. Overall, SA-CZ showed good biocompatibility along with efficient hemostasis and wound healing qualities, making it suitable as a safe and effective aid for bleeding wounds.

Protective Effect of Organ Preservation Fluid Supplemented With Nicorandil and Rutin Trihydrate: A Comparative Study in a Rat Model of Renal Ischemia.

OBJECTIVES: The objective of organ preservation is sustained viability of detached/removed/isolated organs and subsequent successful posttransplant outcomes. Nicorandil (an ATP-sensitive potassium channel opener) is an efficacious agent to preserve lungs and heart. Rutin trihydrate (an antioxidant) inhibits free radical-mediated cytotoxicity and lipid peroxidation. We aimed to evaluate the efficacy of nicorandil and rutin trihydrate to enhance kidney preservation. MATERIALS AND METHODS: We prepared 2 versions of organ preservation fluid, supplemented with either nicorandil or rutin trihydrate, and used 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assays to evaluate the efficacy of these solutions in vitro (HEK293 human embryonic kidney cells), according to various cellular parameters such as ATP levels, reactive oxygen species, and cell viability. We also investigated the in vivo preservation efficacy in a rat model of renal ischemia and evaluated the immunohistological expression of apoptotic markers (caspase 3) in preserved rat kidney. RESULTS: We observed significant improvement of intracellular ATP levels (32 999 ± 1454 pmol/cell, n = 3; P < .05) in cells preserved in the nicorandil- supplemented solution compared with Custodiol solution (23 216 ± 1315 pmol/cell). Reactive oxygen species declined 1.25-fold (P < .05) in the presence of rutin trihydrate. Cell viability assays revealed a 4.8-fold increase in viability of renal cells preserved in the solutions supplemented with nicorandil or rutin trihydrate after 24-hour incubation compared with controls. In vivo, there were significant effects on serum creatinine (0.5480 ± 0.052, 0.956 ± 0.043 mg/dL) and blood urea nitrogen (85.36 ± 4.64, 92.85 ± 3.15 mg/dL) with the nicorandil and rutin trihydrate solutions, respectively. We observed suppressed expression of the apoptotic marker caspase 3 in groups treated with the 2 supplemented preservation fluids. CONCLUSIONS: Our results showed that solutions of organ preservation fluid supplemented with either nicorandil or rutin trihydrate can ameliorate cellular problems/dysfunction and facilitate sustained impro - vement of tissue survival and subsequent organ viability.

Glycolytic inhibitor 2-deoxy-d-glucose attenuates SARS-CoV-2 multiplication in host cells and weakens the infective potential of progeny virions.

AIMS: Virus-infected host cells switch their metabolism to a more glycolytic phenotype, required for new virion synthesis and packaging. Therefore, we investigated the effect and mechanistic action of glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) on virus multiplication in host cells following SARS-CoV-2 infection. MAIN METHODS: SARS-CoV-2 induced change in glycolysis was examined in Vero E6 cells. Effect of 2-DG on virus multiplication was evaluated by RT-PCR (N and RdRp genes) analysis, protein expression analysis of Nucleocapsid (N) and Spike (S) proteins and visual indication of cytopathy effect (CPE), The mass spectrometry analysis was performed to examine the 2-DG induced change in glycosylation status of receptor binding domain (RBD) in SARS-CoV-2 spike protein. KEY FINDINGS: We observed SARS-COV-2 infection induced increased glucose influx and glycolysis, resulting in selectively high accumulation of the fluorescent glucose analog, 2-NBDG in Vero E6 cells. 2-DG inhibited glycolysis, reduced virus multiplication and alleviated cells from virus-induced cytopathic effect (CPE) in SARS-CoV-2 infected cells. The progeny virions produced from 2-DG treated cells were found unglycosylated at crucial N-glycosites (N331 and N343) of the receptor-binding domain (RBD) in the spike protein, resulting in production of defective progeny virions with compromised infective potential. SIGNIFICANCE: The mechanistic study revealed that the inhibition of SARS-COV-2 multiplication is attributed to 2-DG induced glycolysis inhibition and possibly un-glycosylation of the spike protein, also. Therefore, based on its previous human trials in different types of Cancer and Herpes patients, it could be a potential molecule to study in COVID-19 patients.

Mitochondrial uncoupler DNP induces coexistence of dual-state hyper-energy metabolism leading to tumor growth advantage in human glioma xenografts.

Introduction: Cancer bioenergetics is an essential hallmark of neoplastic transformation. Warburg postulated that mitochondrial OXPHOS is impaired in cancer cells, leading to aerobic glycolysis as the primary metabolic pathway. However, mitochondrial function is altered but not entirely compromised in most malignancies, and that mitochondrial uncoupling is known to increase the carcinogenic potential and modifies treatment response by altering metabolic reprogramming. Our earlier study showed that transient DNP exposure increases glycolysis in human glioma cells (BMG-1). The current study investigated the persistent effect of DNP on the energy metabolism of BMG-1 cells and its influence on tumor progression in glioma xenografts. Methods: BMG-1 cells were treated with 2,4-dinitrophenol (DNP) in-vitro, to establish the OXPHOS-modified (OPM-BMG) cells. Further cellular metabolic characterization was carried out in both in-vitro cellular model and in-vivo tumor xenografts to dissect the role of metabolic adaptation in these cells and compared them with their parental phenotype. Results and Discussion: Chronic exposure to DNP in BMG-1 cells resulted in dual-state hyper-energy metabolism with elevated glycolysis++ and OXPHOS++ compared to parental BMG-1 cells with low glycolysis+ and OXPHOS+. Tumor xenograft of OPM-BMG cells showed relatively increased tumor-forming potential and accelerated tumor growth in nude mice. Moreover, compared to BMG-1, OPM-BMG tumor-derived cells also showed enhanced migration and invasion potential. Although mitochondrial uncouplers are proposed as a valuable anti-cancer strategy; however, our findings reveal that prolonged exposure to uncouplers provides tumor growth advantage over the existing glioma phenotype that may lead to poor clinical outcomes.

Sphingosine kinase inhibitor, SKI-II confers protection against the ionizing radiation by maintaining redox homeostasis most likely through Nrf2 signaling.

Exposure to ionizing radiation (IR) set a series of deleterious events causing acute radiation syndrome and mortality, posing the need for a potent and safe radio-protective drug. IR induces cell death predominantly by causing oxidative stress and macromolecular damage. The pre-existing antioxidant defence machinery of the cellular system plays a crucial role in protecting the cells against oxidative stress by activation of Nrf2. The current study was undertaken to investigate the radio-protective potential of sphingosine kinase inhibitor (SKI-II), which was demonstrated to activate Nrf2 signaling. The safety and efficacy of SKI-II were evaluated with cell cytotoxicity, proliferation index, and clonogenic survival assays in different cell lines, namely Raw 264.7, INT-407, IEC-6 and NIH/3T3 cell lines. A safe dose of SKI-II was found radio-protective in all the cell lines linked with the activated antioxidant defence system, thereby resulting in the amelioration of IR induced oxidative stress. SKI-II pretreatment also significantly reduced DNA damage, micronuclei expression, and accelerated DNA repair kinetics as compared to IR exposed cells. Reduced oxidative stress and enhanced DNA repair significantly reduced apoptosis and suppressed the pro-death signaling associated with IR exposure. Furthermore, the in-vitro observation was verified in the in-vivo model (C57 BL/6). The Intra-peritoneal (IP) administration of SKI-II, 2 h before a lethal dose of IR exposure (7.5 Gy) resulted in 75% survival. These results imply that SKI-II ameliorates IR-induced oxidative stress and cell death by inducing anti-oxidant defence system and DNA repair pathways, thus strengthening its potential to be used as radiation countermeasure.

Mild mitochondrial uncoupling protects from ionizing radiation induced cell death by attenuating oxidative stress and mitochondrial damage.

Ionizing radiation (IR) induced mitochondrial dysfunction is associated with enhanced radiation stimulated metabolic oxidative stress that interacts randomly with intracellular bio-macromolecules causing lethal cellular injury and cell death. Since mild mitochondrial uncoupling emerged as a valuable therapeutic approach by regulating oxidative stress in most prevalent human diseases including ageing, ischemic reperfusion injury, and neurodegeneration with comparable features of IR inflicted mitochondrial damage. Therefore, we explored whether mitochondrial uncoupling could also protect from IR induced cytotoxic insult. Our results showed that DNP, BHT, FCCP, and BAM15 are safe to cells at different concentrations range depending on their respective mitochondrial uncoupling potential. Pre-incubation of murine fibroblast (NIH/3T3) cells with the safe concentration of these uncouplers followed by gamma (γ)-radiation showed significant cell growth recovery, reduced ROS generation, and apoptosis, compared to IR treatment alone. We observed that DNP pre-treatment increased the surviving fraction of IR exposed HEK-293, Raw 264.7 and NIH/3T3 cells. Additionally, DNP pre-treatment followed by IR leads to reduced total and mitochondrial oxidative stress (mos), regulated calcium (Ca2+) homeostasis, and mitochondrial bioenergetics in NIH/3T3 cells. It also significantly reduced macromolecular oxidation, correlated with the regulated ROS generation and antioxidant defence system. Moreover, DNP facilitated DNA repair kinetics evidenced by reducing the number of γ-H2AX foci formation and fragmented nuclei with time. DNP pre-incubation restrained the radiation induced pro-apoptotic factors and inhibits apoptosis. Our findings raise the possibility that mild mitochondrial uncoupling with DNP could be a potential therapeutic approach for radiation induced cytotoxic insult associated with an altered mitochondrial function.

Non-Enzymatic Protein Acetylation by 7-Acetoxy-4-Methylcoumarin: Implications in Protein Biochemistry.

BACKGROUND: The semi-synthetic acetoxycoumarins are known to acetylate proteins using novel enzymatic Calreticulin Transacetylase (CRTAase) system in cells. However, the nonenzymatic protein acetylation by polyphenolic acetates is not known. OBJECTIVE: To investigate the ability of 7-acetoxy-4-methyl coumarin (7-AMC) to acetylate proteins non-enzymatically in the test tube. METHODS: We incubated 7-AMC with BSA and analyzed the protein acetylation using Western blot technique. Further, BSA induced biophysical changes in the spectroscopic properties of 7-AMC was analyzed using Fluorescence spectroscopy. RESULTS: Using pan anti-acetyl lysine antibody, herein we demonstrate that 7-AMC acetylates Bovine Serum Albumin (BSA) in time and concentration dependent manner in the absence of any enzyme. 7-AMC is a relatively less fluorescent molecule compared to the parental compound, 7- hydroxy-4-methylcoumarin (7-HMC), however the fluorescence of 7-AMC increased by two fold on incubation with BSA, depending on the time of incubation and concentration of BSA. Analysis of the reaction mixture of 7-AMC and BSA after filtration revealed that the increased fluorescence is associated with the compound of lower molecular weight in the filtrate and not residual BSA, suggesting that the less fluorescent 7-AMC undergoes self-hydrolysis in the presence of protein to give highly fluorescent parental molecule 7-HMC and acetate ion in polar solvent (phosphate buffered saline, PBS). The protein augmented conversion of 7-AMC to 7-HMC was found to be linearly related to the protein concentration. CONCLUSION: Thus protein acetylation induced by 7-AMC could also be non-enzymatic in nature and this molecule can be exploited for quantification of proteins.

Hexokinase II inhibition by 3-bromopyruvate sensitizes myeloid leukemic cells K-562 to anti-leukemic drug, daunorubicin.

An increased metabolic flux towards Warburg phenotype promotes survival, proliferation and causes therapeutic resistance, in leukemic cells. Hexokinase-II (HK-II) is expressed predominantly in cancer cells, which promotes Warburg metabolic phenotype and protects the cancer cells from drug-induced apoptosis. The HK-II inhibitor 3- Bromopyruvate (3-BP) dissociates HK-II from mitochondrial complex, which leads to enhanced sensitization of leukemic cells to anti-leukemic drugs. In the present study, we analyzed the Warburg characteristics viz. HK-II expression, glucose uptake, endogenous reactive oxygen species (ROS) level of leukemic cell lines K-562 and THP-1 and then investigated if 3-BP can sensitize the leukemic cells K-562 to anti-leukemic drug Daunorubicin (DNR). We found that both K-562 and THP-1 cells have multi-fold high levels of HK-II, glucose uptake and endogenous ROS with respect to normal PBMCs. The combined treatment (CT) of 3-BP and DNR showed synergistic effect on the growth inhibition (GI) of K-562 and THP-1 cells. This growth inhibitory effect was attributed to 3-BP induced S-phase block and DNR induced G2/M block, resulted in reduced proliferation due to CT. Further, CT resulted in low HK-II level in mitochondrial fraction, high intracellular calcium and elevated apoptosis as compared with individual treatment of DNR and 3-BP. Moreover, CT caused enhanced DNA damage and hyperpolarized mitochondria, leading to cell death. Taken together, these results suggest that 3-BP synergises the anticancer effects of DNR in the chronic myeloid leukemic cell K-562, and may act as an effective adjuvant to anti-leukemic chemotherapy.

Mitochondrial biogenesis and metabolic hyperactivation limits the application of MTT assay in the estimation of radiation induced growth inhibition.

Metabolic viability based high throughput assays like MTT and MTS are widely used in assessing the cell viability. However, alteration in both mitochondrial content and metabolism can influence the metabolic viability of cells and radiation is a potential mitochondrial biogenesis inducer. Therefore, we tested if MTT assay is a true measure of radiation induced cell death in widely used cell lines. Radiation induced cellular growth inhibition was performed by enumerating cell numbers and metabolic viability using MTT assay at 24 and 48 hours (hrs) after exposure. The extent of radiation induced reduction in cell number was found to be larger than the decrease in MTT reduction in all the cell lines tested. We demonstrated that radiation induces PGC-1α and TFAM to stimulate mitochondrial biogenesis leading to increased levels of SDH-A and enhanced metabolic viability. Radiation induced disturbance in calcium (Ca2+) homeostasis also plays a crucial role by making the mitochondria hyperactive. These findings suggest that radiation induces mitochondrial biogenesis and hyperactivation leading to increased metabolic viability and MTT reduction. Therefore, conclusions drawn on radiation induced growth inhibition based on metabolic viability assays are likely to be erroneous as it may not correlate with growth inhibition and/or loss of clonogenic survival.

Block Copolymer Based Nanoparticles for Theranostic Intervention of Cervical Cancer: Synthesis, Pharmacokinetics, and in Vitro/in Vivo Evaluation in HeLa Xenograft Models.

Polymer-based nanoparticles have proven to be viable carriers of therapeutic agents. In this study, we have developed nanoparticles (NPs) from polypeptide-polyethylene glycol based triblock and diblock copolymers. The synthesized block copolymers poly(ethylene glycol)-b-poly(glutamic acid)-b-poly(ethylene glycol) (GEG) and poly(ethylene glycol)-b-poly(glutamic acid) (EG) conjugated with folic acid for targeting specificity (EGFA) have been used to encapsulate methotrexate (MTX) to form M-GEG and M-EGFA NPs aimed at passive and active targeting of cervical carcinoma. In-vitro SRB cytotoxicity and hemolysis assays revealed that these NPs were cytocompatible to healthy human cells and hemocompatible to human RBCs. Cellular uptake by FACS demonstrated their prompt internalization by human cervical carcinoma (HeLa) cells and points toward an apoptotic mechanism of cell kill as confirmed by AO/EB staining as well as histological analysis of explanted HeLa tumors. Pharmacokinetics and biodistribution studies were performed in New Zealand albino rabbits and HeLa xenografted Athymic mice models, respectively, by radiolabeling these NPs with 99mTc. Passive tumor accumulation and active targeting of MTX-loaded polymeric nanoparticles to folate expressing cells were confirmed by intravenous administration of these 99mTc-labeled M-GEG and M-EGFA NPs in HeLa tumor bearing nude mice and clearly visualized by whole-body gamma-SPECT images of these mice. Survival studies of these xenografted mice established the antiproliferative effect of these MTX-loaded NPs while corroborating the targeting effect of folic acid. These studies proved that the M-GEG NPs and M-EGFA NPs could be effective alternatives to conventional chemotherapy along with simultaneous diagnostic abilities and thus potentially viable theranostic options for human cervical carcinoma.

Transient elevation of glycolysis confers radio-resistance by facilitating DNA repair in cells.

BACKGROUND: Cancer cells exhibit increased glycolysis for ATP production (the Warburg effect) and macromolecular biosynthesis; it is also linked with therapeutic resistance that is generally associated with compromised respiratory metabolism. Molecular mechanisms underlying radio-resistance linked to elevated glycolysis remain incompletely understood. METHODS: We stimulated glycolysis using mitochondrial respiratory modifiers (MRMs viz. di-nitro phenol, DNP; Photosan-3, PS3; Methylene blue, MB) in established human cell lines (HEK293, BMG-1 and OCT-1). Glucose utilization and lactate production, levels of glucose transporters and glycolytic enzymes were investigated as indices of glycolysis. Clonogenic survival, DNA repair and cytogenetic damage were studied as parameters of radiation response. RESULTS: MRMs induced the glycolysis by enhancing the levels of two important regulators of glucose metabolism GLUT-1 and HK-II and resulted in 2 fold increase in glucose consumption and lactate production. This increase in glycolysis resulted in resistance against radiation-induced cell death (clonogenic survival) in different cell lines at an absorbed dose of 5 Gy. Inhibition of glucose uptake and glycolysis (using fasentin, 2-deoxy-D-glucose and 3-bromopyruvate) in DNP treated cells failed to increase the clonogenic survival of irradiated cells, suggesting that radio-resistance linked to inhibition of mitochondrial respiration is glycolysis dependent. Elevated glycolysis also facilitated rejoining of radiation-induced DNA strand breaks by activating both non-homologous end joining (NHEJ) and homologous recombination (HR) pathways of DNA double strand break repair leading to a reduction in radiation-induced cytogenetic damage (micronuclei formation) in these cells. CONCLUSIONS: These findings suggest that enhanced glycolysis generally observed in cancer cells may be responsible for the radio-resistance, partly by enhancing the repair of DNA damage.