Evaluation of the alamarblue assay for adherent cell irradiation experiments

Partial heart transplant valves demonstrate growth in piglets despite prolonged cold storage

BACKGROUND

Traditional heart valve replacement options lack growth potential, limiting their long-term effectiveness in pediatric patients. Partial heart transplantation is an emerging approach that offers growth-capable valves by transplanting only the valve-containing segment of the heart. We report on the effects of extended cold storage on the viability and growth potential of partial heart transplantation grafts.

METHODS

Pulmonary and aortic conduits were harvested from piglets and human donors and stored at 4°C in cold-storage solution, with some samples supplemented with apoptosis inhibitors, membrane stabilizers, and antibiotics to optimize cellular viability. Viability was assessed in vitro over 7 days using the MTS assay. A piglet model of pulmonary valve replacement was used to assess in vivo growth potential after 1 week of cold storage.

RESULTS

In vitro analysis showed a gradual decline in metabolic activity over 7 days, with approximately 50% viability retained in both porcine and human valves. Supplementation with apoptosis inhibitors and membrane stabilizers did not significantly enhance viability. In vivo, transplanted conduits demonstrated robust leaflet and annular growth without significant stenosis or regurgitation, confirming the maintenance of growth potential despite reduced viability.

CONCLUSIONS

Partial heart transplantation grafts can be preserved in cold storage for up to 1 week without significantly compromising in vivo growth potential. These findings support the feasibility of partial heart transplantation as a viable growth-capable valve replacement option for children and suggest that optimized cold storage protocols could facilitate broader access to this technique.

Silk fibroin-hyaluronic acid nanofibers for peripheral nerve regeneration

Peripheral nerve injuries are common and a major source of pain that can lead to debilitating loss of function. Current treatments are limited, with autologous nerve grafts being the gold standard treatment for nerve injuries. However, autografting is not always successful and can lead to increased debilitation through donor site morbidity. Tissue engineering seeks to improve nerve injury treatment though the use of nerve conduits. Conduits made from a functional biomaterial can be implanted into a nerve injury site encouraging and controlling axonal regrowth without causing additional harm to the patient. Both silk fibroin (SF) and hyaluronic acid (HA) have been proven successful in the field of neural tissue engineering. SF has excellent mechanical properties and is biocompatible. HA is part of the extracellular matrix and had been used in nerve regeneration applications. This study developed aligned combination SF-HA nanofibers through electrospinning that could be used within a nerve conduit. Both materials were methacrylated to allow for photocrosslinking and additional control over material properties. Methcrylated SF-HA was tested alongside a material containing only methacrylated HA that has already proven to be effective in literature. When characterizing the materials, it was found that through chemical methacrylation HA was substituted at 60% while SF reported a 30% substitution. Electrospun SF-HA nanofibers were found to have a greater diameter than HA fibers; however, SF-HA was found to be more aligned with greater surface hydrophobicity. Mechanically, it was found that both materials exceeded the elastic modulus of native tissue, but SF-HA far exceeded HA in elasticity and overall fiber extension. Furthermore, human Schwann cells attached, proliferated, and released more pro-regenerative growth factors on SF-HA than HA. Dorsal root ganglia neurons also displayed longer neurite extensions on SF-HA fibers. We concluded that SF-HA nanofibers have potential as a nerve conduit material.

Brasiliensic acid: in vitro cytotoxic and genotoxic, in vivo acute toxicity and in silico pharmacological prediction of a new promising molecule

Brasiliensic acid (Bras) is a chromanone isolated from Calophyllum brasiliense Cambèss. bark extracts with confirmed potential activity on gastric ulcer and Helicobacter pylori infection. This study aimed to investigate the in vitro and in vivo toxicity of Bras and molecular docking studies on its interactions with the H. pylori virulence factors and selected gastric cancer-related proteins. Cytotoxicity was evaluated by alamarBlue© assay, genotoxicity by micronucleus and comet assays, and on cell cycle by flow cytometry, using Chinese hamster epithelial ovary cells. Bras was not cytotoxic to CHO-K1 cells, and caused no chromosomal aberrations, nor altered DNA integrity. Furthermore, Bras inhibited damages to DNA by H2O2 at 1.16 µM. No cell cycle arrest was observed, but apoptosis accounted for 31.2% of the cell death observed in the CHO-K1 at 24 h incubation of the IC50. Oral acute toxicity by Hippocratic screening test in mice showed no relevant behavioral change/mortality seen up to 1,000 mg/kg. The molecular docking approach indicated potential interactions between Bras and the various targets for peptic ulcer and gastric cancer, notably CagA virulence factor of H. pylori and VEGFR-2. In conclusion, Bras is apparently safe and an optimization for Bras can be considered for gastric ulcer and cancer.Communicated by Ramaswamy H. Sarma.

Quantum Sensing Unravels Antioxidant Efficacy Within PCL/Matrigel Skin Equivalents

Skin equivalents (SE) that recapitulate biological and mechanical characteristics of the native tissue are promising platforms for assessing cosmetics and studying fundamental biological processes. Methods to achieve SEs with well-organized structure, and ideal biological and mechanical properties are limited. Here, the combination of melt electrowritten PCL scaffolds and cell-laden Matrigel to fabricate SE is described. The PCL scaffold provides ideal structural and mechanical properties, preventing deformation of the model. The model consists of a top layer for seeding keratinocytes to mimic the epidermis, and a bottom layer of Matrigel-based dermal compartment with fibroblasts. The compressive modulus and the biological properties after 3-day coculture indicate a close resemblance with the native skin. Using the SE, a testing system to study the damage caused by UVA irradiation and evaluate antioxidant efficacy is established. The effectiveness of Tea polyphenols (TPs) and L-ascorbic acid (Laa) is compared based on free radical generation. TPs are demonstrated to be more effective in downregulating free radical generation. Further, T1 relaxometry is used to detect the generation of free radicals at a single-cell level, which allows tracking of the same cell before and after UVA treatment.

Quantification of cellular phototoxicity of organelle stains by the dynamics of microtubule polymerization

Being able to quantify the phototoxicity of dyes and drugs in live cells allows biologists to better understand cell responses to exogenous stimuli during imaging. This capability further helps to design fluorescent labels with lower phototoxicity and drugs with better efficacy. Conventional ways to evaluate cellular phototoxicity rely on late-stage measurements of individual or different populations of cells. Here, we developed a quantitative method using intracellular microtubule polymerization as a rapid and sensitive marker to quantify early-stage phototoxicity. Implementing this method, we assessed the photosensitization induced by organelle dyes illuminated with different excitation wavelengths. Notably, fluorescent markers targeting mitochondria, nuclei, and endoplasmic reticulum exhibited diverse levels of phototoxicity. Furthermore, leveraging a real-time precision opto-control technology allowed us to evaluate the synergistic effect of light and dyes on specific organelles. Studies in hypoxia revealed enhanced phototoxicity of Mito-Tracker Red CMXRos that is not correlated with the generation of reactive oxygen species but a different deleterious pathway in low oxygen conditions.

Toward Defect-Free Nanoimprinting

Nanoimprinting large-area structures, especially high-density features like meta lenses, poses challenges in achieving defect-free nanopatterns. Conventional high-resolution molds for nanoimprinting are often expensive, typically constructed from inorganic materials such as silicon, nickel (Ni), or quartz. Unfortunately, replicated nanostructures frequently suffer from breakage or a lack of definition during demolding due to the high adhesion and friction at the polymer-mold interface. Moreover, mold degradation after a limited number of imprinting cycles, attributed to contamination and damaged features, is a common issue. In this study, a disruptive approach is presented to address these challenges by successfully developing an anti-sticking nanocomposite mold. This nanocomposite mold is created through the co-deposition of nickel atoms and low surface tension polytetrafluoroethylene (PTFE) nanoparticles via electroforming. The incorporation of PTFE enhances the ease of polymer release from the mold. The resulting Ni-PTFE nanocomposite mold exhibits exceptional lubrication properties and a significantly reduced surface energy. This robust nanocomposite mold proves effective in imprinting fine, densely packed nanostructures down to 100 nm using thermal nanoimprinting for at least 20 cycles. Additionally, UV nanoimprint lithography (UV-NIL) is successfully performed with this nanocomposite mold. This work introduces a novel and cost-effective approach to reusable high-resolution molds, ensuring defect-reduction production in nanoimprinting.

Melt electrowritten poly-lactic acid /nanodiamond scaffolds towards wound-healing patches

Multifunctional wound dressings, enriched with biologically active agents for preventing or treating infections and promoting wound healing, along with cell delivery capability, are highly needed. To address this issue, composite scaffolds with potential in wound dressing applications were fabricated in this study. The poly-lactic acid/nanodiamonds (PLA/ND) scaffolds were first printed using melt electrowriting (MEW) and then coated with quaternized β-chitin (QβC). The NDs were well-dispersed in the printed filaments and worked as fillers and bioactive additions to PLA material. Additionally, they improved coating effectiveness due to the interaction between their negative charges (from NDs) and positive charges (from QβC). NDs not only increased the thermal stability of PLA but also benefitted cellular behavior and inhibited the growth of bacteria. Scaffolds coated with QβC increased the effect of bacteria growth inhibition and facilitated the proliferation of human dermal fibroblasts. Additionally, we have observed rapid extracellular matrix (ECM) remodeling on QβC-coated PLA/NDs scaffolds. The scaffolds provided support for cell adhesion and could serve as a valuable tool for delivering cells to chronic wound sites. The proposed PLA/ND scaffold coated with QβC holds great potential for achieving fast healing in various types of wounds.

Challenging applicability of ISO 10993-5 for calcium phosphate biomaterials evaluation: Towards more accurate in vitro cytotoxicity assessment

Research on biomaterials typically starts with cytocompatibility evaluation, using the ISO 10993-5 standard as a reference that relies on extract tests to determine whether the material is safe (cell metabolic activity should exceed 70 %). However, the generalized approach within the standard may not accurately reflect the material's behavior in direct contact with cells, raising concerns about its effectiveness. Calcium phosphates (CaPs) are a group of materials that, despite being highly biocompatible and promoting bone formation, still exhibit inconsistencies in basic cytotoxicity evaluations. Hence, in order to test the cytocompatibility dependence on different experimental setups and material-cell interactions, we used amorphous calcium phosphate, α-tricalcium phosphate, hydroxyapatite, and octacalcium phosphate (0.1 mg/mL to 5 mg/mL) with core cell lines of bone microenvironment: mesenchymal stem cells, osteoblast-like and endothelial cells. All materials have been characterized for their physicochemical properties before and after cellular contact and once in vitro assays were finalized, groups identified as 'cytotoxic' were further analyzed using a modified Annexin V apoptosis assay to accurately determine cell death. The obtained results showed that indirect contact following ISO standards had no sensitivity of tested cells to the materials, but direct contact tests at physiological concentrations revealed decreased metabolic activity and viability. In summary, our findings offer valuable guidelines for handling biomaterials, especially in powder form, to better evaluate their biological properties and avoid false negatives commonly associated with the traditional standard approach.

Evaluation of the cytotoxicity, antioxidant activity, and molecular docking of biogenic zinc oxide nanoparticles derived from pumpkin seeds

This study aimed to investigate the characterization of zinc oxide nanoparticles (ZnONPs) produced from Cucurbita pepo L. (pumpkin seeds) and their selective cytotoxic effectiveness on human colon cancer cells (HCT 116) and African Green Monkey Kidney, Vero cells. The study also investigated the antioxidant activity of ZnONPs. The study also examined ZnONPs' antioxidant properties. This was motivated by the limited research on the comparative cytotoxic effects of ZnO NPs on normal and HCT116 cells. The ZnO NPs were characterized using Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Transmission Electron Microscope/Selected Area Electron Diffraction (TEM/SAED), and Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) for determination of chemical fingerprinting, heat stability, size, and morphology of the elements, respectively. Based on the results, ZnO NPs from pumpkins were found to be less than 5 μm and agglomerates in nature. Furthermore, the ZnO NPs fingerprinting and SEM-EDX element analysis were similar to previous literature, suggesting the sample was proven as ZnO NPs. The ZnO NPs also stable at a temperature of 380°C indicating that the green material is quite robust at 60-400°C. The cell viability of Vero cells and HCT 116 cell line were measured at two different time points (24 and 48 h) to assess the cytotoxicity effects of ZnO NP on these cells using AlamarBlue assay. Cytotoxic results have shown that ZnO NPs did not inhibit Vero cells but were slightly toxic to cancer cells, with a dose-response curve IC50 = ~409.7 μg/mL. This green synthesis of ZnO NPs was found to be non-toxic to normal cells but has a slight cytotoxicity effect on HCT 116 cells. A theoretical study used molecular docking to investigate nanoparticle interaction with cyclin-dependent kinase 2 (CDK2), exploring its mechanism in inhibiting CDK2's role in cancer. Further study should be carried out to determine suitable concentrations for cytotoxicity studies. Additionally, DPPH has a significant antioxidant capacity, with an IC50 of 142.857 μg/mL. RESEARCH HIGHLIGHTS: Pumpkin seed extracts facilitated a rapid, high-yielding, and environmentally friendly synthesis of ZnO nanoparticles. Spectrophotometric analysis was used to investigate the optical properties, scalability, size, shape, dispersity, and stability of ZnO NPs. The cytotoxicity of ZnO NPs on Vero and HCT 116 cells was assessed, showing no inhibition of Vero cells and cytotoxicity of cancer cells. The DPPH assay was also used to investigate the antioxidant potential of biogenic nanoparticles. A molecular docking study was performed to investigate the interaction of ZnO NPs with CDK2 and to explore the mechanism by which they inhibit CDK2's role in cancer.

Investigation of Cannabinoid Acid/Cyclodextrin Inclusion Complex for Improving Physicochemical and Biological Performance

This study aimed to investigate the enhancement of cannabinoid acid solubility and stability through the formation of a cannabinoid acid/cyclodextrin (CD) inclusion complex. Two cannabinoid acids, tetrahydro-cannabinolic acid (THCA) and cannabidiolic acid (CBDA), were selected as a model drug along with five types of CD: α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and methylated-β-cyclodextrin (M-β-CD). Phase solubility studies were conducted using various types of CD to determine the complex stoichiometry. The preparation methods of the CD inclusion complex were optimized by adjusting the loading pH solution and the drying processes (spray-drying, freeze-drying, spray-freeze-drying). The drying process of the cannabinoid acid/M-β-CD inclusion complex was further optimized through the spray-freeze-drying method. These CD complexes were characterized using solubility determination, differential scanning calorimetry (DSC), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and 1H NMR spectroscopy. DSC, XRD, and FE-SEM studies confirmed the non-crystalline state of the cannabinoid acid/CD inclusion complex. The permeation of THCA or CBDA from the M-β-CD spray-freeze-dried inclusion complex was highly improved compared to those of cannabis ethanolic extracts under simulated physiological conditions. The stability of the cannabinoid acid/M-β-CD inclusion complex was maintained for 7 days in a simulated physiological condition. Furthermore, the minimum inhibitory concentration of cannabinoid acid/M-β-CD inclusion complex had superior anti-cancer activity in MCF-7 breast cancer cell lines compared to cannabinoid acid alone. The improved physicochemical and biological performances indicated that these CD inclusion complexes could provide a promising option for loading lipophilic cannabinoids in cannabis-derived drug products.

Applications and Advances of Multicellular Tumor Spheroids: Challenges in Their Development and Analysis

Biomedical research requires both in vitro and in vivo studies in order to explore disease processes or drug interactions. Foundational investigations have been performed at the cellular level using two-dimensional cultures as the gold-standard method since the early 20th century. However, three-dimensional (3D) cultures have emerged as a new tool for tissue modeling over the last few years, bridging the gap between in vitro and animal model studies. Cancer has been a worldwide challenge for the biomedical community due to its high morbidity and mortality rates. Various methods have been developed to produce multicellular tumor spheroids (MCTSs), including scaffold-free and scaffold-based structures, which usually depend on the demands of the cells used and the related biological question. MCTSs are increasingly utilized in studies involving cancer cell metabolism and cell cycle defects. These studies produce massive amounts of data, which demand elaborate and complex tools for thorough analysis. In this review, we discuss the advantages and disadvantages of several up-to-date methods used to construct MCTSs. In addition, we also present advanced methods for analyzing MCTS features. As MCTSs more closely mimic the in vivo tumor environment, compared to 2D monolayers, they can evolve to be an appealing model for in vitro tumor biology studies.

Increased glucose influx and glycogenesis in lung cancer cells surviving after irradiation

PURPOSE

Lung cancer is considered as one of the most frequent malignancies worldwide. Radiotherapy is the main treatment modality applied for locally advanced disease, but remnant surviving cancer tissue results in disease progression in the majority of irradiated lung carcinomas. Metabolic reprogramming is regarded as a cancer hallmark and is associated with resistance to radiation therapy. Here, we explored metabolic alterations possibly related to cancer cell radioresistance.

MATERIALS AND METHODS

We compared the expression of metabolism-related enzymes in the parental A549 lung cancer cell line along with two new cell lines derived from A549 cells after recovery from three (A549-IR3) and six (A549-IR6) irradiation doses with 4 Gy. Differential GLUT1 and GYS1 expression on proliferation and radioresistance were also comparatively investigated.

RESULTS

A549-IR cells displayed increased extracellular glucose absorption, and enhanced mRNA and protein levels of the GLUT1 glucose transporter. GLUT1 inhibition with BAY-876, suppressed cell proliferation and the effect was significantly more profound on A549-IR3 cells. Protein levels of molecules associated with aerobic or anaerobic glycolysis, or the phosphate pentose pathway were similar in all three cell lines. However, glycogen synthase 1 (GYS1) was upregulated, especially in the A549-IR3 cell line, suggestive of glycogen accumulation in cells surviving post irradiation. GYS1-gene silencing repressed the proliferation capacity of A549, but this increased their radioresistance. The radio-protective effect of the suppression of proliferative activity induced by GYS1 silencing did not protect A549-IR3 cells against further irradiation.

CONCLUSIONS

These findings indicate that GYS1 activity is a critical component of the metabolism of lung cancer cells surviving after fractionated radiotherapy. Targeting the glycogen metabolic reprogramming after irradiation may be a valuable approach to pursue eradication of the post-radiotherapy remnant of disease.

Toward the Scalable Fabrication of Fully Bio-Based Antimicrobial and UVB-Blocking Transparent Polylactic Acid Films That Incorporate Natural Coatings and Nanopatterns

Microbial transmissions via membrane surface and single-use plastic-induced pollution are two urgent societal problems. This research introduces a scalable fabrication strategy for fully biobased antibacterial and ultraviolet-B block polylactic acid (PLA) films integrating natural coatings and nanopatterns via ultrasonic atomization spray coating and thermal nanoimprinting lithography (TNIL) techniques, respectively. Tannic acid (TA) and gallic acid (GA) were formulated prior to TNIL using anode aluminum oxide template. Results reveal that TA and GA inks display intense adsorption in the UVB region. Plasma increases the hydrophilicity of PLA films for fast spreading of ink droplets. Micron-sized pillars observed on film confirm the successful structural replication. TA-coated PLA films display higher transparency than GA-coated ones. Nanopatterned PLA films have a modest antibacterial resistance of c. 45% against Escherichia coli. TA/GA coatings, however, impart PLA films with a bacterial reduction rate of over 80%. The integration of a TA or GA coating with nanopatterns further promotes the antibacterial rate up to 98%. The cytocompatibility of TA and GA demonstrates that the engineered film can potentially be applied as food packaging. Finally, a continuous mass production strategy is proposed along with an outline of the associated challenges and costs. This study provides a scalable strategy to the sustainable development of eco-benign and functional films.

In vitro chemosensitivity of a canine tumor venereal transmissible cancer cell line

The canine transmissible venereal tumor (CTVT) is the most common malignity in dogs. Because there are reports that this tumor is resistant to vincristine sulfate, the chemotherapeutic options are scarce, and the development of new therapeutic approaches is necessary. In this study, we evaluated the cytotoxic activity of vincristine, doxorubicin, temozolomide, panobinostat, toceranib, gemcitabine, cisplatin, fluorouracil, cyclophosphamide, and methotrexate on a CTVT cell line, determining that all drugs decreased the viability in a dose-dependent manner. Furthermore, they inhibit cellular migration in a time- and drug-dependent manner, as evaluated by the wound healing assay. On the other hand, vincristine, panobinostat, gemcitabine, toceranib, cyclophosphamide, and methotrexate increased the percentage of cells in the subG1 phase, and doxorubicin, temozolomide, gemcitabine, toceranib, and methotrexate decreased the percentage of cells in the synthesis phase. To efficientize the use of vincristine, only toceranib increased the cytotoxic effect of vincristine in a synergistic manner. Our results confirm the use of vincristine as the gold standard for CTVT treatment as monotherapy and suggest the use of a combinatorial and sequential treatment with toceranib.

HOXB9 Overexpression Promotes Colorectal Cancer Progression and Is Associated with Worse Survival in Liver Resection Patients for Colorectal Liver Metastases

As is known, HOXB9 is an important factor affecting disease progression and overall survival (OS) in cancer. However, its role in colorectal cancer (CRC) remains unclear. We aimed to explore the role of HOXB9 in CRC progression and its association with OS in colorectal liver metastases (CRLM). We analysed differential HOXB9 expression in CRC using the Tissue Cancer Genome Atlas database (TCGA). We modulated HOXB9 expression in vitro to assess its impact on cell proliferation and epithelial-mesenchymal transition (EMT). Lastly, we explored the association of HOXB9 protein expression with OS, using an institutional patient cohort (n = 110) who underwent liver resection for CRLM. Furthermore, HOXB9 was upregulated in TCGA-CRC (n = 644) vs. normal tissue (n = 51) and its expression levels were elevated in KRAS mutations (p < 0.0001). In vitro, HOXB9 overexpression increased cell proliferation (p < 0.001) and upregulated the mRNA expression of EMT markers (VIM, CDH2, ZEB1, ZEB2, SNAI1 and SNAI2) while downregulated CDH1, (p < 0.05 for all comparisons). Conversely, HOXB9 silencing disrupted cell growth (p < 0.0001). High HOXB9 expression (HR = 3.82, 95% CI: 1.59-9.2, p = 0.003) was independently associated with worse OS in CRLM-HOXB9-expressing patients after liver resection. In conclusion, HOXB9 may be associated with worse OS in CRLM and may promote CRC progression, whereas HOXB9 silencing may inhibit CRC growth.

Lipophagy-related protein perilipin-3 (PLIN3) and resistance of prostate cancer to radiotherapy

PURPOSE

Radiotherapy is a principal treatment modality for localized and locally advanced prostate cancer (PCa). Metabolic alterations, including lipid metabolism, may reduce treatment efficacy resulting in tumor relapse and poor therapeutic outcome. In the current study, we investigated the role of the lipophagy-related protein perilipin-3 (PLIN3) and the lysosomal acid lipase (LAL) in PCa response to radiotherapy.

METHODS AND MATERIALS

We explored the in vitro and xenograft (in NOD.SCID and R2G2 mice) response to radiation of either PLIN3-depleted or LAL-depleted hormone-refractory (DU145, PC3), and hormone-responsive 22Rv1 PCa cell lines. Moreover, we evaluated the clinical role of PLIN3 and LAL protein expression in a series of PCa tissue specimens from patients treated with radical radiotherapy.

RESULTS

In vitro and in vivo experiments showed reduced proliferation and strong radiosensitization of all studied PCa cell lines upon PLIN3 depletion. In vivo experiments demonstrated the significantly augmented radiotherapy efficacy upon PLIN3 depletion, resulting in extensive tissue necrosis. PLIN3 overexpression in tissue specimens was correlated with increased MIB1 proliferation index, increased autophagy flux, reduced response to radiotherapy and poor prognosis. The impact of LAL depletion on radiotherapy was of lesser importance.

CONCLUSIONS

Assessment of PLIN3 expression may identify subgroups of PCa patients less responsive to radiotherapy, and at high risk of relapse post irradiation. Whether radiotherapy efficacy may be enhanced by concurrent autophagy or PLIN3 inhibition in this sub-group of patients demands clinical evaluation.

Apalutamide radio-sensitisation of prostate cancer

INTRODUCTION

The combination of radiotherapy with bicalutamide is the standard treatment of prostate cancer patients with high-risk or locally advanced disease. Whether new-generation anti-androgens, like apalutamide, can improve the radio-curability of these patients is an emerging challenge.

MATERIALS AND METHODS

We comparatively examined the radio-sensitising activity of apalutamide and bicalutamide in hormone-sensitive (22Rv1) and hormone-resistant (PC3, DU145) prostate cancer cell lines. Experiments with xenografts were performed for the 22Rv1 cell line.

RESULTS

Radiation dose-response viability and clonogenic assays showed that apalutamide had a stronger radio-sensitising activity for all three cell lines. Confocal imaging for γΗ2Αx showed similar DNA double-strand break repair kinetics for apalutamide and bicalutamide. No difference was noted in the apoptotic pathway. A striking cell death pattern involving nuclear karyorrhexis and cell pyknosis in the G1/S phase was exclusively noted when radiation was combined with apalutamide. In vivo experiments in SCID and R2G2 mice showed significantly higher efficacy of radiotherapy (2 and 4 Gy) when combined with apalutamide, resulting in extensive xenograft necrosis.

CONCLUSIONS

In vitro and in vivo experiments support the superiority of apalutamide over bicalutamide in combination with radiotherapy in prostate cancer. Clinical studies are encouraged to show whether replacement of bicalutamide with apalutamide may improve the curability rates.

DNA Dyes-Highly Sensitive Reporters of Cell Quantification: Comparison with Other Cell Quantification Methods

Cell quantification is widely used both in basic and applied research. A typical example of its use is drug discovery research. Presently, plenty of methods for cell quantification are available. In this review, the basic techniques used for cell quantification, with a special emphasis on techniques based on fluorescent DNA dyes, are described. The main aim of this review is to guide readers through the possibilities of cell quantification with various methods and to show the strengths and weaknesses of these methods, especially with respect to their sensitivity, accuracy, and length. As these methods are frequently accompanied by an analysis of cell proliferation and cell viability, some of these approaches are also described.

Suppressed PLIN3 frequently occurs in prostate cancer, promoting docetaxel resistance via intensified autophagy, an event reversed by chloroquine

Lipid metabolism reprogramming is one of the adaptive events that drive tumor development and survival, and may account for resistance to chemotherapeutic drugs. Perilipins are structural proteins associated with lipophagy and lipid droplet integrity, and their overexpression is associated with tumor aggressiveness. Here, we sought to explore the role of lipid droplet-related protein perilipin-3 (PLIN3) in prostate cancer (PCa) chemotherapy. We investigated the role of PLIN3 suppression in docetaxel cytotoxic activity in PCa cell lines. Additional effects of PLIN3 depletion on autophagy-related proteins and gene expression patterns, apoptotic potential, proliferation rate, and ATP levels were examined. Depletion of PLIN3 resulted in docetaxel resistance, accompanied by enhanced autophagic flux. We further assessed the synergistic effect of autophagy suppression with chloroquine on docetaxel cytotoxicity. Inhibition of autophagy with chloroquine reversed chemoresistance of stably transfected shPLIN3 PCa cell lines, with no effect on the parental ones. The shPLIN3 cell lines also exhibited reduced Caspase-9 related apoptosis initiation. Moreover, we assessed PLIN3 expression in a series of PCa tissue specimens, were complete or partial loss of PLIN3 expression was frequently noted in 70% of the evaluated specimens. Following PLIN3 silencing, PCa cells were characterized by impaired lipophagy and acquired an enhanced autophagic response upon docetaxel-induced cytotoxic stress. Such an adaptation leads to resistance to docetaxel, which could be reversed by the autophagy blocker chloroquine. Given the frequent loss of PLIN3 expression in PCa specimens, we suggest that combination of docetaxel with chloroquine may improve the efficacy of docetaxel treatment in PLIN3-deficient cancer patients.

Biochemical impact of solar radiation exposure on human keratinocytes monitored by Raman spectroscopy; effects of cell culture environment

Understanding and amelioration of the effects of solar radiation exposure are critical in preventing the occurrence of skin cancer. Towards this end, many studies have been conducted in 2D cell culture models under simplified and unrealistic conditions. 3D culture models better capture the complexity of in vivo physiology, although the effects of the 3D extracellular matrix have not been well studied. Monitoring the instantaneous and resultant cellular responses to exposure, and the influence of the 3D environment, could provide an enhanced understanding of the fundamental processes of photocarcinogenesis. This work presents an analysis of the biochemical impacts of simulated solar radiation (SSR) occurring in immortalised human epithelial keratinocytes (HaCaT), in a 3D skin model, compared to 2D culture. Cell viability was monitored using the Alamar Blue colorimetric assay (AB), and the impact of the radiation exposure, at the level of the biomolecular constituents (nucleic acids and proteins), were evaluated through the combination of Raman microspectroscopy and multivariate statistical analysis. The results suggest that SSR exposure induces alterations of the conformational structure of DNA as an immediate impact, whereas changes in the protein signature are primarily seen as a subsequent response.

Vitrification of particulated articular cartilage via calculated protocols

Preserving viable articular cartilage is a promising approach to address the shortage of graft tissue and enable the clinical repair of articular cartilage defects in articulating joints, such as the knee, ankle, and hip. In this study, we developed two 2-step, dual-temperature, multicryoprotectant loading protocols to cryopreserve particulated articular cartilage (cubes ~1 mm3 in size) using a mathematical approach, and we experimentally measured chondrocyte viability, metabolic activity, cell migration, and matrix productivity after implementing the designed loading protocols, vitrification, and warming. We demonstrated that porcine and human articular cartilage cubes can be successfully vitrified and rewarmed, maintaining high cell viability and excellent cellular function. The vitrified particulated articular cartilage was stored for a period of 6 months with no significant deterioration in chondrocyte viability and functionality. Our approach enables high-quality long-term storage of viable articular cartilage that can alleviate the shortage of grafts for use in clinically repairing articular cartilage defects.

Evaluation of an electrochemically aligned collagen yarn for textile scaffold fabrication

Collagen is the major component of the extracellular matrix in human tissues and widely used in the fabrication of tissue engineered scaffolds for medical applications. However, these forms of collagen gels and films have limitations due to their inferior strength and mechanical performance and their relatively fast rate of degradation. A new form of continuous collagen yarn has recently been developed for potential usage in fabricating textile tissue engineering scaffolds. In this study, we prepared the continuous electrochemical aligned collagen yarns from acid-soluble collagen that was extracted from rat tail tendons (RTTs) using 0.25 M acetic acid. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy confirmed that the major component of the extracted collagen contained alpha 1 and alpha 2 chains and the triple helix structure of Type 1 collagen. The collagen solution was processed to monofilament yarns in continuous lengths by using a rotating electrode electrochemical compaction device. Exposing the non-crosslinked collagen yarns and the collagen yarns crosslinked with 1-ethyl-3-(-3-dimethyl-aminopropyl) carbodiimide hydrochloride to normal physiological hydrolytic degradation conditions showed that both yarns were able to maintain their tensile strength during the first 6 weeks of the study. Cardiosphere-derived cells showed significantly enhanced attachment and proliferation on the collagen yarns compared to synthetic polylactic acid filaments. Moreover, the cells were fully spread and covered the surface of the collagen yarns, which confirmed the superiority of collagen in terms of promoting cellular adhesion. The results of this work indicated that the aligned RTT collagen yarns are favorable for fabricating biotextile scaffolds and are encouraging for further studies of various textile structure for different tissue engineering applications.

Monitoring the biochemical changes occurring to human keratinocytes exposed to solar radiation by Raman spectroscopy

Solar radiation exposure is recognised to be a significant contributor to the development of skin cancer. Monitoring the simultaneous and consecutive mechanisms of interaction could provide a greater understanding of the process of photocarcinogenesis. This work presents an analysis of the biochemical and morphological changes occurring to immortalised human epithelial keratinocyte (HaCaT) cell cultures exposed to simulated solar radiation (SSR). Cell viability was monitored with the aid of the Alamar Blue assay, morphological examination was done with haematoxylin and eosin staining (H&E) and changes to the biochemical constituents (nucleic acids and proteins) as a result of the radiation insult were demonstrated through a combination of Raman microspectroscopy and multivariate analysis of spectral patterns. The spectral results suggest that SSR induces changes to the conformational structure of DNA as an immediate result of the radiation, whereas alteration in the protein signature is mostly seen as a later response.

6-Nitro-Quinazolin-4(3H)-one Exhibits Photodynamic Effects and Photodegrades Human Melanoma Cell Lines. A Study on the Photoreactivity of Simple Quinazolin-4(3H)-ones

Photochemo and photodynamic therapies are minimally invasive approaches for the treatment of cancers and powerful weapons for competing bacterial resistance to antibiotics. Synthetic and naturally occurring quinazolinones are considered privileged anticancer and antibacterial agents, with several of them to have emerged as commercially available drugs. In the present study, applying a single-step green microwave irradiation mediated protocol we have synthesized eleven quinazolinon-4(3H)-ones, from cheap readily available anthranilic acids, in very good yields and purity. These products were irradiated in the presence of pBR322 plasmid DNA under UVB, UVA and visible light. Four of the compounds proved to be very effective DNA photocleavers, at low concentrations, being time and concentration dependent as well as pH independent. Participation of reactive oxygen species was related to the substitution of quinazolinone derivatives. 6-Nitro-quinazolinone in combination with UVA irradiation was found to be in vitro photodestructive for three cell lines; glioblastoma (U87MG and T98G) and mainly melanoma (A-375). Thus, certain appropriately substituted quinazolinones may serve as new lead photosensitizers for the development of promising biotechnological applications and as novel photochemo and photodynamic therapeutics.

Silk fibroin nanoscaffolds for neural tissue engineering

The nervous system is a crucial component of the body and damages to this system, either by injury or disease, can result in serious or potentially lethal consequences. An important problem in neural engineering is how we can stimulate the regeneration of damaged nervous tissue given its complex physiology and limited regenerative capacity. To regenerate damaged nervous tissue, this study electrospun three-dimensional nanoscaffolds (3DNSs) from a biomaterial blend of silk fibroin (SF), polyethylene glycol (PEG), and polyvinyl alcohol (PVA). The 3DNSs were characterised to ascertain their potential suitability for direct implant into the CNS. The biological activity of 3DNSs was investigated in vitro using PC12 cells and their effects on reactive astrogliosis were assessed in vivo using a photothrombotic model of ischaemic stroke in mice. Results showed that the concentration of SF directly affected the mechanical characteristics and internal structure of the 3DNSs, with formulations presenting as either a gel-like structure (SF ≥ 50%) or a nanofibrous structure (SF ≤ 40%). In vitro assessment revealed increased cell viability in the presence of the 3DNSs and in vivo assessment resulted in a significant decrease in glial fibrillary acidic protein (GFAP) expression in the peri-infarct region (p < 0.001 for F2 and p < 0.05 for F4) after stroke, suggesting that 3DNSs could be suppressing reactive astrogliosis. The findings enhanced our understanding of physiochemical interactions between SF, PEG, and PVA, and elucidated the potential of 3DNSs as a potential therapeutic approach to stroke recovery, especially if these are used in conjunction with drug or cell treatment.

The Effect of Antimicrobial Peptides on the Viability of Human Corneal Epithelial Cells

Antimicrobial peptides are polypeptides composed of less than 100 amino acids and are a class of antibiotics with strong activity against some infectious bacteria. This study examined the safety of four chosen antimicrobial peptides using primary human corneal epithelial cells (HCEC) and explored their potential therapeutic use. The efficacy of the peptides was also studied by evaluating the minimum inhibitory concentrations (MIC) against Gram-negative and Gram-positive bacteria. One of the peptides (polymyxin E) was found to have antibacterial efficacy against a common Gram-negative bacterium (MIC 1.56 μg/mL for Pseudomonas aeruginosa), and another one (nisin) was found to have antibacterial efficacy against a common Gram-positive bacterium (MIC 125 μg/mL for Staphylococcus aureus). Metabolic activity and live/dead/apoptotic effects were measured with fluorescent dyes after HCEC were exposed to the peptides for 30 min. Three of the peptides exhibited lower toxicity against HCEC than a currently marketed eye drop product. Regarding both efficacy and safety, two of the peptides (polymyxin E and nisin) were found to have potential use for treating ocular infections.

22β-hydroxytingenone reduces proliferation and invasion of human melanoma cells

Melanoma is a skin cancer with high invasive potential and high lethality. Considering that quinonemethide triterpenes are described as promising anticancer agents, the aim of this study was to evaluate the effect of 22β-hydroxytingenone (22-HTG) against human melanoma cells. Alamar blue assay was performed in order to evaluate its cytotoxic effect. Thus, subtoxic concentrations (1.0, 2.0, and 2.5 μM) were used to evaluate the effect of this compound on proliferation, migration, metabolism, and invasion. IC₅₀ value against SK-MEL-28 cell line was 4.35, 3.72, and 3.29 μM after 24, 48, and 72 h of incubation, respectively. 22-HTG reduced proliferation, migration and invasion by melanoma cells, with decreased activity of metalloproteinases (MMP-2 and MMP-9). Futhermore, 22-HTG decreased expression of lactate dehydrogenase (LDHA), an enzyme associated with cell metabolism. Howerver, the small reduction in LDHA enzyme activity must have occurred by the cytotoxic effect of 22-HTG. According to the results, 22-HTG interferes with important characteristics of cancer, with anti-proliferative, and anti-invasive effect against melanoma cells. The data suggest that 22-HTG is an effective substance against melanoma cells and it should be considered as a potential anticancer agent.

Comparison of three multi-cryoprotectant loading protocols for vitrification of porcine articular cartilage

Vitrification is a cryopreservation technique for the long-term storage of viable tissue, but the success of this technique relies on multiple factors. In 2012, our group published a working vitrification protocol for intact human articular cartilage and reported promising chondrocyte recovery after using a four-step multi-cryoprotectant (CPA) loading method that required 570 min. However, this protocol requires further optimization for clinical practice. Herein, we compared three multi-step CPA loading protocols to investigate their impact on chondrocyte recovery after vitrification of porcine articular cartilage on a bone base, including our previous four-step protocol (original: 570 min), and two shorter three-step protocols (optimized: 420 min, and minimally vitrifiable: 310 min). Four different CPAs were used including glycerol, dimethyl sulfoxide, ethylene glycol and propylene glycol. As vitrification containers, two conical tubes (50 ml and 15 ml) were evaluated for their heat transfer impact on chondrocyte recovery after vitrification. Osteochondral dowels were cored into two diameters of 10.0 mm and 6.9 mm with an approximately 10-mm thick bone base, and then allocated into the twelve experimental groups based on CPA loading protocol, osteochondral dowel size, and vitrification container size. After vitrification at -196 °C and tissue warming and CPA removal, samples in all groups were assessed for both chondrocyte viability and metabolic activity. The optimized protocol proposed based on mathematical modelling resulted in similar chondrocyte recovery to our original protocol and it was 150 min shorter. Furthermore, this study illustrated the role of CPA permeation (dowel size) and heat transfer (container size) on vitrification protocol outcome.

Quantification of fixed adherent cells using a strong enhancer of the fluorescence of DNA dyes

Cell quantification is widely used in basic or applied research. The current sensitive methods of cell quantification are exclusively based on the analysis of non-fixed cells and do not allow the simultaneous detection of various cellular components. A fast, sensitive and cheap method of the quantification of fixed adherent cells is described here. It is based on the incubation of DAPI- or Hoechst 33342-stained cells in a solution containing SDS. The presence of SDS results in the quick de-staining of DNA and simultaneously, in an up-to-1,000-fold increase of the fluorescence intensity of the used dyes. This increase can be attributed to the micelle formation of SDS. The method is sufficiently sensitive to reveal around 50–70 human diploid cells. It is compatible with immunocytochemical detections, the detection of DNA replication and cell cycle analysis by image cytometry. The procedure was successfully tested for the analysis of cytotoxicity. The method is suitable for the quantification of cells exhibiting low metabolic activity including senescent cells. The developed procedure provides high linearity and the signal is high for at least 20 days at room temperature. Only around 90 to 120 minutes is required for the procedure’s completion.

'Stemness' and 'senescence' related escape pathways are dose dependent in lung cancer cells surviving post irradiation

AIMS

Lung cancer is one of the main causes of cancer-related deaths worldwide and radiotherapy is a major treatment of choice. However, radioresistance is a main reason for radiotherapy failure or tumor relapse. Here, we investigated possible mechanisms associated with cancer cell radioresistance.

MATERIALS AND METHODS

We compared two newly derived cell lines, namely A549-IR3 and A549-IR6, which survived repeated (3 or 6 times) 4 Gy exposure of parental A549 lung cancer cell line. DNA repair ability, stemness and senescence were comparatively studied.

KEY FINDINGS

A549-IR3 exhibited higher proliferation ability and radioresistance compared to parental and A549-IR6 cells. Enhanced radioresistance was not accompanied by chemoresistance to cisplatin or docetaxel. DNA repair kinetics (γΗ2ΑΧ expression) were similar in all cell lines. A549-IR3 cells exhibited a significant rise in stem cell markers (CD44, CD133, OCT4, SOX2 and NANOG) whereas A549-IR6 displayed an increased senescent population.

SIGNIFICANCE

Cancer cells surviving after radiotherapy may follow two different escape pathways: selection for radioresistance resulting in regrowth, and in clinical terms relapse, or above an irradiation threshold, stem-cells die and cancer cells become senescent, leading the tumor to a state of dormancy.

HDAC8 overexpression in mesenchymal stromal cells from JAK2+ myeloproliferative neoplasms: a new therapeutic target?

Histone deacetylases (HDACs) are involved in epigenetic modulation and their aberrant expression has been demonstrated in myeloproliferative neoplasms (MPN). HDAC8 inhibition has been shown to inhibit JAK2/STAT5 signaling in hematopoietic cells from MPN. Nevertheless, the role of HDAC8 expression in bone marrow-mesenchymal stromal cells (BM-MSC) has not been assessed. In the current work we describe that HDAC8 is significantly over-expressed in MSC from in JAK-2 positive MPN compared to those from healthy-donors (HD-MSC). Using a selective HDAC8 inhibitor (PCI34051), we verified that the subsequent decrease in the protein and mRNA expression of HDAC8 is linked with an increased apoptosis of malignant MSC whereas it has no effects on normal MSC. In addition, HDAC8 inhibition in MPN-MSC also decreased their capacity to maintain neoplastic hematopoiesis, by increasing the apoptosis, cell-cycle arrest and colony formation of JAK2⁺-hematopoietic cells. Mechanistic studies using different MPN cell lines revealed that PCI34051 induced their apoptosis, which is enhanced when were co-cultured with JAK2V617F-MSC, decreased their colony formation and the phosphorylation of STAT3 and STAT5. In summary, we show for the first time that the inhibition of HDAC8 in MSC from JAK2⁺ MPN patients selectively decreases their hematopoietic-supporting ability, suggesting that HDAC8 may be a potential therapeutic target in this setting by acting not only on hematopoietic cells but also on the malignant microenvironment.

Autophagic flux response and glioblastoma sensitivity to radiation

Objective:

Glioblastoma is the most common primary brain tumor in adults and one of the most lethal human tumors. It constitutes a unique non-metastasizing human tumor model with high resistance to radiotherapy and chemotherapy. The current study investigates the association between autophagic flux and glioblastoma cell resistance.

Methods:

The expression kinetics of autophagy- and lysosome-related proteins following exposure of two glioblastoma cell lines (T98 and U87) to clinically relevant radiation doses was examined. Then, the response of cells resistant to radiotherapy and chemotherapy was investigated after silencing of LC3A, LC3B, and TFEB genes in vitro and in vivo.

Results:

Following irradiation with 4 Gy, the relatively radioresistant T98 cells exhibited enhanced autophagic flux. The more radiosensitive U87 cell line suffered a blockage of autophagic flux. Silencing of LC3A, LC3B, and TFEB genes in vitro, significantly sensitized cells to radiotherapy and temozolomide (U87: P < 0.01 and < 0.05, respectively; T98: P < 0.01 and < 0.01, respectively). Silencing of the LC3A gene sensitized mouse xenografts to radiation.

Conclusions:

Autophagy in cancer cells may be a key factor of radio-resistance and chemo-resistance in glioblastoma cells. Blocking autophagy may improve the efficacy of radiochemotherapy for glioblastoma patients.

Assessment of Radiobiological α/β Ratio in Lung Cancer and Fibroblast Cell Lines Using Viability Assays

BACKGROUND/AIM

Altered fractionation is an area of intense clinical research in radiation oncology. Estimation of the α/β ratio of individual carcinomas after establishment of primary cell cultures from tumor biopsies may prove of importance in the individualization of radiotherapy schemes.

MATERIALS AND METHODS

Here we proposed a simple method to estimate the α/β ratio in cultured cell lines (two lung carcinomas: A549 and H1299; one lung fibroblast cell line: MRC5), using viability assays.

RESULTS

For the A549 cell line, the α/β ratio ranged from 14-25 Gy, for H1299 from 11-43 Gy and for the MRC5 fibroblast cell line this was far lower, ranging from 0.69 to 6 Gy. The α/β ratio decreased when extracted from comparisons of lower dose per fraction schemes.

CONCLUSION

The α/β ratio of a cell line can be easily defined after simple viability/dose fractionation experiments.

Inhibition of IKK-NFκB pathway sensitizes lung cancer cell lines to radiation

Objective

: Cancer cell radioresistance is a stumbling block in radiation therapy. The activity in the nuclear factor kappa B (NFκB) pathway correlates with anti-apoptotic mechanisms and increased radioresistance. The IKK complex plays a major role in NFκB activation upon numerous signals. In this study, we examined the interaction between ionizing radiation (IR) and different members of the IKK-NFκB pathway, as well as upstream activators, RAF1, ERK, and AKT1.

Methods

: The effect of 4 Gy of IR on the expression of the RAF1-ERK-IKK-NFκB pathway was examined in A549 and H1299 lung cancer cell lines using Western blot analysis and confocal microscopy. We examined changes in radiation sensitivity using gene silencing or pharmacological inhibitors of ERK and IKKβ.

Results

: IKKα, IKKγ, and IκBα increased upon exposure to IR, thereby affecting nuclear levels of NFκB (phospho-p65). ERK inhibition or siRNA-mediated down-regulation of RAF1 suppressed the post-irradiation survival of the examined lung cancer cell lines. A similar effect was detected on survival upon silencing IKKα/IKKγ or inhibiting IKKβ.

Conclusions

: Exposure of lung cancer cells to IR results in NFκB activation via IKK. The genetic or pharmacological blockage of the RAF1-ERK-IKK-NFκB pathway sensitizes cells to therapeutic doses of radiation. Therefore, the IKK pathway is a promising target for therapeutic intervention in combination with radiotherapy.

Disulfiram anti-cancer efficacy without copper overload is enhanced by extracellular H2O2 generation: antagonism by tetrathiomolybdate

Highlights

Background

Cu/Zn superoxide dismutases (SODs) like the extracellular SOD3 and cytoplasmic SOD1 regulate cell proliferation by generating hydrogen peroxide (H₂O₂). This pro-oxidant inactivates essential cysteine residues in protein tyrosine phosphatases (PTP) helping receptor tyrosine kinase activation by growth factor signaling, and further promoting downstream MEK/ERK linked cell proliferation. Disulfiram (DSF), currently in clinical cancer trials is activated by copper chelation, being potentially capable of diminishing the copper dependent activation of MEK1/2 and SOD1/SOD3 and promoting reactive oxygen species (ROS) toxicity. However, copper (Cu) overload may occur when co-administered with DSF, resulting in toxicity and mutagenicity against normal tissue, through generation of the hydroxyl radical (•OH) by the Fenton reaction.

Purpose

To investigate: a) whether sub-toxic DSF efficacy can be increased without Cu overload against human melanoma cells with unequal BRAF(V600E) mutant status and Her2-overexpressing SKBR3 breast cancer cells, by increasing H₂O₂from exogenous SOD; b) to compare the anti-tumor efficacy of DSF with that of another clinically used copper chelator, tetrathiomolybdate (TTM)

Results

a) without copper supplementation, exogenous SOD potentiated sub-toxic DSF toxicity antagonized by sub-toxic TTM or by the anti-oxidant N-acetylcysteine; b) exogenous glucose oxidase, another H₂O₂ generator resembled exogenous SOD in potentiating sub-toxic DSF.

Conclusions

potentiation of sub-lethal DSF toxicity by extracellular H₂O₂ against the human tumor cell lines investigated, only requires basal Cu and increased ROS production, being unrelated to non-specific or TTM copper chelator sequestration.

Significance

These findings emphasize the relevance of extracellular H₂O₂ as a novel mechanism to improve disulfiram anticancer effects minimizing copper toxicity.

Repression of the autophagic response sensitises lung cancer cells to radiation and chemotherapy

Background:

The cellular autophagic response to radiation is complex. Various cells and tissues respond differentially to radiation, depending on both the dose of exposure and the time post irradiation. In the current study, we determined the autophagosomal and lysosomal response to radiation in lung cancer cell lines by evaluating the expression of the associated proteins, as well as the effect of relevant gene silencing in radio and chemosensitisation. Furthermore, tumour sensitisation was evaluated in in vivo autophagic gene silencing model after irradiation.

Methods:

A549 and H1299 cell lines were utilised as in vitro cancer models. Both cell lines were transfected with various small-interfering RNAs, silencing auto-lysosomal genes, and irradiated with 4 Gy. Cell growth response was evaluated with AlamarBlue assay. Western blot and confocal microscopy were utilised for the characterisation of the auto-lysosomal flux. Also, the H1299 cell line was stable transfected with small-hairpin RNA of the MAP1LC3A gene, and the tumour radiosensitisation in Athymic Nude-Foxn1^nu was evaluated.

Results:

Following exposure to 4 Gy of radiation, A549 cells exhibited a significant induction of the autophagic flux, which was not supported by transcriptional activation of auto-lysosomal genes (LC3A, LC3B, p62, TFEB and LAMP2a), resulting in aggresome accumulation. Recovery of transcriptional activity and autophagy efficacy occurred 7 days post irradiation. Alternatively, H1299 cells, a relatively radio-resistant cell line, sharply responded with an early (at 2 days) transcriptional activation of auto-lysosomal genes that sustained an effective autophagosomal flux, resulting in adequate aggresome clearance. Subsequently, we tested the silencing of four genes (LC3A, LC3B, TFEB and LAMP2a), confirming a significant radiosensitisation and chemosensitisation to various chemotherapeutic agents, including cisplatin and taxanes. In mouse xenografts, exposure to radiation significantly reduced tumour growth (P<0.001), which was exacerbated among shLC3A-H1299 transfected tumours.

Conclusions:

The ability of lung cancer cells to survive after irradiation at 4 Gy depends on their ability to sustain a functional autophagic flux. Abrogation of such ability results in increased radiosensitivity and susceptibility to various chemotherapy agents. Selective inhibitors of cancer cell autophagic function may prove important for the eradication of lung cancer.

Hypoxia-inducible proteins HIF1α and lactate dehydrogenase LDH5, key markers of anaerobic metabolism, relate with stem cell markers and poor post-radiotherapy outcome in bladder cancer

PURPOSE

To assess whether anaerobic metabolism, proliferation activity and stem cell content are linked with radioresistance in bladder cancer.

MATERIALS AND METHODS

Tissue sections from 66 patients with invasive transitional cell bladder cancer treated with hypofractionated accelerated radiotherapy, was immunohistochemically analyzed for the Hypoxia-Inducible Factor 1α (HIF1α) and the anaerobic glycolysis enzyme lactate dehydrogenase 5 (LDH5). Proliferation index (Ki-67) and stem-cell marker (cluster of differentiation CD44, aldehyde dehydrogenase ALDH1) expression was also examined.

RESULTS

Both HIF1α and LDH5 expression were linked with high CD44 stem cell population (p = 0.001 and 0.05, respectively), while high Ki-67 proliferation index was linked with nuclear LDH5 expression (p = 0.03) and high histological grade (p = 0.02). A strong significant association of HIF1α (p = 0.0009) and of LDH5 (p < 0.0001) with poor local relapse free survival (LRFS) was noted, which was also confirmed in multivariate analysis. A significant association with overall survival was also noted. Silencing of lactate dehydrogenase LDHA gene in the human RT112 bladder cancer cell line, or exposure to oxamate (LDH activity inhibitor), resulted in strong radio-sensitization.

CONCLUSIONS

HIF1α and LDH5 are markers of poor outcome in patients with bladder cancer treated with radiotherapy. Blockage of anaerobic metabolism may prove of importance in clinical radiotherapy.

Intensified autophagy compromises the efficacy of radiotherapy against prostate cancer

INTRODUCTION

Radiotherapy is an equivalent alternative or complement to radical prostatectomy, with high therapeutic efficacy. High risk patients, however, experience high relapse rates, so that research on radio-sensitization is the most evident route to improve curability of this common disease.

MATERIALS AND METHODS

In the current study we investigated the autophagic activity in a series of patients with localized prostate tumors treated with radical radiotherapy, using the LC3A and the LAMP2a proteins as markers of autophagosome and lysosome cellular content, respectively. The role of autophagy on prostate cancer cell line resistance to radiation was also examined.

RESULTS

Using confocal microscopy on tissue biopsies, we showed that prostate cancer cells have, overall, high levels of LC3A and low levels of LAMP2a compared to normal prostate glands. Tumors with a 'highLC3A/lowLAMP2a' phenotype, suggestive of intensified lysosomal consumption, had a significantly poorer biochemical relapse free survival. The PC3 radioresistant cell line sustained remarkably its autophagic flux ability after radiation, while the DU145 radiosensitive one experiences a prolonged blockage of the autophagic process. This was assessed with aggresome accumulation detection and LC3A/LAMP2a double immunofluorescence, as well as with sequestrosome/p62 protein detection. By silencing the LC3A or LAMP2a expression, both cell lines became more sensitive to escalated doses of radiation.

CONCLUSIONS

High base line autophagy activity and cell ability to sustain functional autophagy define resistance of prostate cancer cells to radiotherapy. This can be reversed by blocking up-regulated components of the autophagy pathway, which may prove of importance in the field of clinical radiotherapy.

Fever-range hyperthermia vs. hypothermia effect on cancer cell viability, proliferation and HSP90 expression

Purpose

The current study examines the effect of fever-range hyperthermia and mild hypothermia on human cancer cells focusing on cell viability, proliferation and HSP90 expression.

Materials and Methods

A549 and H1299 lung carcinoma, MCF7 breast adenocarcinoma, U87MG and T98G glioblastoma, DU145 and PC3 prostate carcinoma and MRC5 normal fetal lung fibroblasts cell lines were studied. After 3-day exposure to 34°C, 37°C and 40°C, cell viability was determined. Cell proliferation (ki67 index), apoptosis (Caspase 9) and HSP90 expression was studied by confocal microscopy.

Results

Viability/proliferation experiments demonstrated that MRC5 fibroblasts were extremely sensitive to hyperthermia, while they were the most resistant to hypothermia. T98G and A549 were thermo-tolerant, the remaining being thermo-sensitive to a varying degree. Nonetheless, as a universal effect, hypothermia reduced viability/proliferation in all cell lines. Hyperthermia sharply induced Caspase 9 in the U87MG most thermo-sensitive cell line. In T98G and A549 thermo-tolerant cell lines, the levels of Caspase 9 declined. Moreover, hyperthermia strongly induced the HSP90 levels in T98G, whilst a sharp decrease was recorded in the thermo-sensitive PC3 and U87MG cell lines. Hyperthermia sensitized thermo-sensitive cancer cell lines to cisplatin and temozolomide, whilst its sensitizing effect was diminished in thermo-tolerant cell lines.

Conclusions

The existence of thermo-tolerant and thermo-sensitive cancer cell lines was confirmed, which further encourages research to classify human tumor thermic predilection for patient stratification in clinical trials. Of interest, mild hypothermia had a universal suppressing effect on cancer cell proliferation, further supporting the radio-sensitization hypothesis through reduction of oxygen and metabolic demands.

Important role of autophagy in endothelial cell response to ionizing radiation

Objectives

Vasculature damage is an important contributor to the side-effects of radiotherapy. The aim of this study is to provide insights into the radiobiology of the autophagic response of endothelial cells.

Methods and Materials

Human umbilical vascular endothelial cells (HUVEC) were exposed to 2 Gy of ionizing radiation (IR) and studied using confocal microscopy and western blot analysis, at 4 and 8 days post-irradiation. The role of autophagy flux in HUVEC radio-sensitivity was also examined.

Results

IR-induced accumulation of LC3A+, LC3B+ and p62 cytoplasmic vacuoles, while in double immunostaining with lysosomal markers (LAMP2a and CathepsinD) repression of the autophagolysosomal flux was evident. Autophagy-related proteins (ATF4, HIF1α., HIF2α, Beclin1) were, however, induced excluding an eventual repressive effect of radiation on autophagy initiating protein expression. Exposure of HUVEC to SMER28, an mTOR-independent inducer of autophagy, enhanced proLC3 and LC3A, B-I protein expression and accelerated the autophagic flux. Pre-treatment of HUVEC with SMER28 protected against the blockage of autophagic flux induced by IR and conferred radio-resistance. Suppression of LC3A/LC3B proteins with siRNAs resulted in radio-sensitization.

Conclusions

The current data provide a rationale for the development of novel radioprotection policies targeting the autophagic pathway.

Lactate dehydrogenase 5 isoenzyme overexpression defines resistance of prostate cancer to radiotherapy

Background:

Radiotherapy provides high-cure rates in prostate cancer. Despite its overall slow clinical growth, high proliferation rates documented in a subset of tumours relate to poor radiotherapy outcome. This study examines the role of anaerobic metabolism in prostate cancer growth and resistance to radiotherapy.

Methods:

Biopsy samples from 83 patients with prostate cancer undergoing radical hypofractionated and accelerated radiotherapy were analysed for MIB1 proliferation index and for lactate dehydrogenase isoenzyme LDH5, a marker of tumour anaerobic metabolism. Ninety-five surgical samples were in parallel analysed. Correlation with histopathological variables, PSA and radiotherapy outcome was assessed. Dose–response experiments were performed in PC3 and DU145 cancer cell lines.

Results:

High MIB1 index (noted in 25% of cases) was directly related to Gleason score (P<0.0001), T3-stage (P=0.0008) and PSA levels (P=0.03). High LDH5 (noted in 65% of cases) was directly related to MIB1 index (P<0.0001), Gleason score (P=0.02) and T3-stage (P=0.001). High Gleason score, MIB1, LDH5 and PSA levels were significantly related to poor BRFS (P=0.007, 0.01, 0.03 and 0.01, respectively). High Gleason score (P=0.04), LDH5 (P=0.01) and PSA levels (P=0.003) were significantly related to local recurrence. MIB1 and T-stage did not affect local control. Silencing of LDHA gene in both prostate cancer cell lines resulted in significant radiosensitisation.

Conclusions:

LDH5 overexpression is significantly linked to highly proliferating prostate carcinomas and with biochemical failure and local relapse following radiotherapy. Hypoxia and LDHA targeting agents may prove useful to overcome radioresistance in a subgroup of prostate carcinomas with anaerobic metabolic predilection.