p53 mutant human glioma cells are sensitive to UV-C-induced apoptosis due to impaired cyclobutane pyrimidine dimer removal

Hybrid Radiant Disinfection: Exploring UVC and UVB Sterilization Impact on the Mechanical Characteristics of PLA Materials

This study explores the impact of disinfection techniques on the mechanical properties of poly(lactic acid) (PLA), a crucial material in the production of medical implants, tissue engineering, orthopedic devices and drug delivery systems, owing to its biocompatibility and ease of manufacturing. The focus is on evaluating the effectiveness of ultraviolet (UV) type C (254 nm wavelength) and the combined use of type C and B (310 nm wavelength) disinfection methods. Fifteen tensile test specimens (ASTM D638) and fifteen compression test specimens (ASTM D695) were utilized to assess PLA's mechanical properties, including yield strength, ultimate strength, and fracture strength. The investigation involved subjecting the specimens to the specified disinfection methods and evaluating these properties both before and after the disinfection process. In the tensile test, a statistically significant difference (p = 0) in yield displacement was observed among the three groups. Additionally, a notable difference (p = 0.047) in fracture displacement was identified between the untreated group and the UVC and UVB combination group. No discernible impact on yield or fracture forces was noted. In the compression test, there was a significant difference (p = 0.04) in yield displacement and a clear difference (p = 0.05) in fracture force between the untreated group and the UVC and UVB combination group. The hybrid combination of UVC and UVB disinfection techniques did not affect yield force in both tensile and compression tests. However, it demonstrated a clear impact on displacement, suggesting its potential as a promising disinfection technique in the medical field.

XPC multifaceted roles beyond DNA damage repair: p53-dependent and p53-independent functions of XPC in cell fate decisions

Xeroderma pigmentosum group C protein (XPC) acts as a DNA damage recognition factor for bulky adducts and as an initiator of global genome nucleotide excision repair (GG-NER). Novel insights have shown that the role of XPC is not limited to NER, but is also implicated in DNA damage response (DDR), as well as in cell fate decisions upon stress. Moreover, XPC has a proteolytic role through its interaction with p53 and casp-2S. XPC is also able to determine cellular outcomes through its interaction with downstream proteins, such as p21, ARF, and p16. XPC interactions with effector proteins may drive cells to various fates such as apoptosis, senescence, or tumorigenesis. In this review, we explore XPC's involvement in different molecular pathways in the cell and suggest that XPC can be considered not only as a genomic caretaker and gatekeeper but also as a tumor suppressor and cellular-fate decision maker. These findings envisage that resistance to cell death, induced by DNA-damaging therapeutics, in highly prevalent P53-deficent tumors might be overcome through new therapeutic approaches that aim to activate XPC in these tumors. Moreover, this review encourages care providers to consider XPC status in cancer patients before chemotherapy in order to improve the chances of successful treatment and enhance patients' survival.

The Effects of Ultraviolet Light-Emitting Diodes with Different Wavelengths on Periodontopathic Bacteria In Vitro

Objective: The aim of this study was to examine effects of recently developed ultraviolet light-emitting diodes (UV LEDs) wavelengths on in vitro growth and gene expression of cultural periodontopathic bacteria, and on viability of experimental gingival fibroblasts. Materials and methods: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Streptococcus oralis were irradiated by UV LEDs (265, 285, 310, 365, and 448 nm) at 600 mJ/cm² and grown anaerobically in vitro. The colony forming units were counted after 1 week. Cell morphology was observed using a scanning electron microscope (SEM). Quantitative real-time polymerase chain reaction was performed to investigate gene expression changes by 310 nm irradiation. Viability of the irradiated human gingival fibroblasts was evaluated using WST-8 assay. Results: Both 265 and 285 nm resulted in the complete death of bacteria and fibroblasts, whereas 310 nm caused partial killing and suppression of bacterial growth and much less damage to the fibroblasts in vitro. Both 365 and 448 nm resulted in no significant change. SEM showed that P. gingivalis cells gradually degraded from day 2 or 3 and were severely destructed on day 5 for 265, 285, and 310 nm. The 310 nm irradiation transiently suppressed the transcripts of SOS response- and cell division-relative genes. Conclusions: Both 265 and 285 nm may induce powerful bactericidal effects and severe fibroblast phototoxicity, and 310 nm may induce partial killing or growth suppression of bacterial cells with much less fibroblast phototoxicity. UV lights may have potential for bacterial suppression, with situations dependent on wavelength, in periodontal and peri-implant therapy.

Cytotoxicity of ultraviolet-C radiation on a heterogeneous population of human glioblastoma multiforme cells: Meta-analysis

INTRODUCTION

Current treatment strategies for glioblastoma multiforme are limited due to early recurrence and heterogeneity of the cell population that causes a varied response to treatment. Ultraviolet-C (UVC) radiation may be a potential adjuvant treatment that could theoretically be delivered locally by implantable micro-electromechanical systems that sense and kill early recurrence and/or minimally residual cancer. in vitro irradiation experiments are limited because they commonly use a single cell line. Therefore other methods are required to investigate cytotoxicity across a heterogeneous population of GBM.

METHODS

A meta-analysis was conducted to assess the cytotoxic effects of UVC radiation on human GBM cell lines, with or without genetic modification, in monolayer to simulate a heterogeneous model. 16 publications were included using 14 different cell lines and 19 gene vectors. Effect sizes were calculated for cell survival, viability, apoptosis and proliferation. Univariate meta-regression was used to investigate the effects of radiant exposure (J/m²) and timing on cytotoxicity.

RESULTS

UVC resulted in a 70.9% (CI: 63.6%-78.2%) reduction in survival, 16.6% (CI: 10.8%-22.4%) increase in apoptosis, 32.0% (CI: 9.95%-54.2%) reduction in viability, and 413.8% (CI: 95.7%-731.9%) reduction in proliferation of GBM cell lines compared to controls. Radiant exposure was significantly associated with survival (R² = 0.486, p < 0.0001) but not with apoptosis or viability.

CONCLUSIONS

This study provides more data on the therapeutic translational potential of UVC to a more clinically-realistic context. Overall, UVC is cytotoxic to GBM cell lines in aggregate and may be clinically useful when combined with genetic modification or other adjuvant treatments.

BmK CT enhances the sensitivity of temozolomide-induced apoptosis of malignant glioma U251 cells in vitro through blocking the AKT signaling pathway

Temozolomide (TMZ) is a drug that has been demonstrated to improve the survival time of patients with glioblastoma multiforme (GBM) when administered with concomitant radiotherapy. However, chemoresistance is one of the major obstacles in the treatment of GBM. In the present study, an MTT assay and flow cytometry were used to demonstrate that chlorotoxin-like toxin in the venom of the scorpion Buthus martensii Kirsch (BmK CT) markedly inhibited cell proliferation and induced apoptosis in U251 cells when combined with TMZ. In combination with TMZ, BmK CT exhibited a significant and synergistic anti-tumor effect by inhibiting protein kinase B (AKT) independently and triggering the apoptosis signaling cascade in vitro. Furthermore, BmK CT increased the expression of phosphatase and tensin homolog at the transcriptional level, which is a key negative regulator of the AKT signaling pathway. The results of the present study demonstrated that BmK CT enhanced the sensitivity of TMZ-induced U251 cell apoptosis through the downregulation of phosphorylated AKT levels, suggesting that BmK CT and TMZ combination therapy may be a novel approach for glioma therapy.

Effects of Ultraviolet Radiation on Glioma: Systematic Review

Glioblastoma multiforme is the most aggressive primary brain tumor. Treatment is largely palliative, with current strategies unable to prevent inevitable tumor recurrence. Implantable micro-electromechanical systems are becoming more feasible for the management of several human diseases. These systems may have a role in detecting tumor recurrence and delivering localized therapies. One potential therapeutic tool is ultraviolet (UV) light. This systematic review assesses the effects of UV light on glioma cells. A total of 47 publications are included. The large majority were in vitro experiments conducted on human glioblastoma cell lines in monolayer. In these cells, UV light was shown to induce apoptosis and the expression of genes or activation of proteins that modulate cell death, repair, and proliferation. The nature and magnitude of cellular response varied by UV wavelength, dose, cell line, and time after irradiation. UVC (wavelength 100-280 nm) was most effective at inducing apoptosis, and this effect was dose dependent. The included studies had varied methodologies, complicating reconciliation of results. Further work will be required to determine the best regime of UV irradiation for therapeutic use. J. Cell. Biochem. 118: 4063-4071, 2017. © 2017 Wiley Periodicals, Inc.

Bactericidal effects of 310 nm ultraviolet light-emitting diode irradiation on oral bacteria

Background

Ultraviolet (UV) light is used for phototherapy in dermatology, and UVB light (around 310 nm) is effective for treatment of psoriasis and atopic dermatitis. In addition, it is known that UVC light (around 265 nm) has a bactericidal effect, but little is known about the bactericidal effect of UVB light. In this study, we examined the bactericidal effects of UVB-light emitting diode (LED) irradiation on oral bacteria to explore the possibility of using a 310 nm UVB-LED irradiation device for treatment of oral infectious diseases.

Methods

We prepared a UVB (310 nm) LED device for intraoral use to examine bactericidal effects on Streptococcus mutans, Streptococcus sauguinis, Porphyromonas gingivalis, and Fusobacterium nucleatum and also to examine the cytotoxicity to a human oral epithelial cell line (Ca9–22). We also examined the production of nitric oxide and hydrogen peroxide from Ca9–22 cells after irradiation with UVB-LED light.

Results

Irradiation with the 310 nm UVB-LED at 105 mJ/cm² showed 30–50% bactericidal activity to oral bacteria, though 17.1 mJ/cm² irradiation with the 265 nm UVC-LED completely killed the bacteria. Ca9–22 cells were strongly injured by irradiation with the 265 nm UVC-LED but were not harmed by irradiation with the 310 nm UVB-LED. Nitric oxide and hydrogen peroxide were produced by Ca9–22 cells with irradiation using the 310 nm UVB-LED. P. gingivalis was killed by applying small amounts of those reactive oxygen species (ROS) in culture, but other bacteria showed low sensitivity to the ROS.

Conclusions

Narrowband UVB-LED irradiation exhibited a weak bactericidal effect on oral bacteria but showed low toxicity to gingival epithelial cells. Its irradiation also induces the production of ROS from oral epithelial cells and may enhance bactericidal activity to specific periodontopathic bacteria. It may be useful as a new adjunctive therapy for periodontitis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-017-0382-5) contains supplementary material, which is available to authorized users.

Axially-modified paddlewheel diruthenium(II,III)-ibuprofenato metallodrugs and the influence of the structural modification on U87MG and A172 human glioma cell proliferation, apoptosis, mitosis and migration

The metallodrug chloridotetrakis(ibuprofenato)diruthenium(II,III) ([Ru₂(Ibp)₄Cl] or RuIbpCl (1), Ibp=carboxylate anion derived from the non-steroidal anti-inflammatory drug ibuprofen) has shown promising results in vitro and in vivo, which point to its potential as an inhibitor of glioma tumour growth in vivo. In order to get insight into the influence of structural changes on the biological response of the metallodrug, the [Ru₂(Ibp)₄] metal-metal multiply bonded paddlewheel unit was modified for the axial ligand. Two new analogues, [Ru₂(Ibp)₄(CF₃SO₃)] (2) and [Ru₂(Ibp)₄(EtOH)₂]PF₆ (3), were synthesized and fully characterized by elemental analysis, ESI-MS, vibrational (FTIR, Raman) and electronic (UV/VIS/NIR) spectroscopy, magnetic susceptibility, molar conductivity measurements, and thermal analysis. RuIbpCl was re-prepared and complementary characterization to previous work was performed. The three axially-modified RuIbp metallodrugs were compared for their effects on U87MG and A172 human glioma cell proliferation, apoptosis, mitosis, and cell migration in vitro. The results provide evidence that the chloride ligand in RuIbpCl may play key role in the mode of action of the metallodrug, since the best results for antiproliferative activity were found for (1) in both types of human glioma cells. All the metallodrugs, (1), (2) and (3), were uptaken by the cells, and were shown to cause increase on number of apoptotic cells and decrease on number of mitotic cells. Additionally, the RuIbp metallodrugs were capable of inhibiting cell migration process in both human glioma cell lines. These data are extremely promising as drugs which can inhibit both cell proliferation/mitosis and inhibit cell migration could target two major chemotherapeutic targets in high grade gliomas.

Combination of lentivirus-mediated silencing of PPM1D and temozolomide chemotherapy eradicates malignant glioma through cell apoptosis and cell cycle arrest

Temozolomide (TMZ) is approved for use as first-line treatment for glioblastoma multiforme (GBM). However, GBM shows chemoresistance shortly after the initiation of treatment. In order to detect whether silencing of human protein phosphatase 1D magnesium dependent (PPM1D) gene could increase the effects of TMZ in glioma cells, glioma cells U87-MG were infected with lentiviral shRNA vector targeting PPM1D silencing. After PPM1D silencing was established, cells were treated with TMZ. The multiple functions of human glioma cells after PPM1D silencing and TMZ chemotherapy were detected by flow cytometry and MTT assay. Significantly differentially expressed genes were distinguished by microarray-based gene expression profiling and analyzed by gene pathway enrichment analysis and ontology assessment. Western blotting was used to establish the protein expression of the core genes. PPM1D gene silencing improves TMZ induced cell proliferation and induces cell apoptosis and cell cycle arrest. When PPM1D gene silencing combined with TMZ was performed in glioma cells, 367 genes were upregulated and 444 genes were downregulated compared with negative control. The most significant differential expression pathway was pathway in cancer and IGFR1R, PIK3R1, MAPK8 and EP300 are core genes in the network. Western blotting showed that MAPK8 and PIK3R1 protein expression levels were upregulated and RB1 protein expression was decreased. It was consistent with that detected in gene expression profiling. In conclusion, PPM1D gene silencing combined with TMZ eradicates glioma cells through cell apoptosis and cell cycle arrest. PIK3R1/AKT pathway plays a role in the multiple functions of glioma cells after PPM1D silencing and TMZ chemotherapy.

Lipocalin 2 Enhances Migration and Resistance against Cisplatin in Endometrial Carcinoma Cells

PURPOSE

Lipocalin 2 (LCN2) is a secretory protein that is involved in various physiological processes including iron transport. We previously identified LCN2 as an up-regulated gene in endometrial carcinoma, and found that the overexpression of LCN2 and its receptor, SLC22A17, was associated with a poor prognosis. However, the functions and mechanism of action of LCN2 currently remain unclear.

METHODS

The LCN2-overexpressing endometrial carcinoma cell lines, HHUA and RL95-2, and LCN2-low-expressing one, HEC1B, were used. The effects of LCN2 on cell migration, cell viability, and apoptosis under various stresses, including ultraviolet (UV) irradiation and cisplatin treatment, were examined using the scratch wound healing assay, WST-1 assay, and Apostrand assay, respectively.

RESULTS

LCN2-silencing using shRNA method significantly reduced the migration ability of cells (p<0.05). Cytotoxic stresses significantly decreased the viability of LCN2-silenced cells more than that of control cells. In contrast, LCN2 overexpression was significantly increased cisplatin resistance. These effects were canceled by the addition of the iron chelator, deferoxamine. After UV irradiation, the expression of phosphorylated Akt (pAkt) was decreased in LCN2-silenced cells, and the PI3K inhibitor canceled the difference induced in UV sensitivity by LCN2. The cisplatin-induced expression of pAkt was not affected by LCN2; however, the expression of p53 and p21 was increased by LCN2-silencing.

CONCLUSIONS

These results indicated that LCN2 was involved in the migration and survival of endometrial carcinoma cells under various stresses in an iron-dependent manner. The survival function of LCN2 may be exerted through the PI3K pathway and suppression of the p53-p21 pathway. These functions of LCN2 may increase the malignant potential of endometrial carcinoma cells.

Chloroquine-induced glioma cells death is associated with mitochondrial membrane potential loss, but not oxidative stress

Chloroquine (CQ), a quinolone derivative widely used to treat and prevent malaria, has been shown to exert a potent adjuvant effect when combined with conventional glioblastoma therapy. Despite inducing lysosome destabilization and activating p53 in human glioma cells, the mechanisms underlying cell death induced by this drug are poorly understood. Here, we analyzed in a time- and dose-dependent manner, the effects of CQ upon mitochondria integrity, autophagy regulation and redox processes in four human glioma cell lines that differ in their resistance to this drug. NAC-containing media protected cells against CQ-induced loss of mitochondrial membrane potential (MMP), autophagic vacuoles (LC3II) accumulation and loss of cell viability induced by CQ. However, we noticed that part of this protection was due to media acidification in NAC preparations, alerting for problems in experimental procedures using NAC. The results indicate that although CQ induces accumulation of LC3II, mitochondria, and oxidative stress, neither of these events is clearly correlated to cell death induced by this drug. The only event elicited in all cell lines at equitoxic doses of CQ was the loss of MMP, indicating that mitochondrial stability is important for cells resistance to this drug. Finally, the data indicate that higher steady-state MMP values can predict cell resistance to CQ treatment.

Growth inhibitory effects of the Diruthenium-Ibuprofen compound, [Ru2Cl(Ibp) 4], in human glioma cells in vitro and in the rat C6 orthotopic glioma in vivo

The Diruthenium-Ibuprofen compound [Ru2Cl(Ibp)4] (or RuIbp) is known to cause significant inhibition of C6 rat glioma cell proliferation in vitro. RuIbp increased the expression of cell cycle-related proteins such as p21 and p27 and the pro-apoptotic protein Bax, as well as causing a reduction in mitochondrial membrane potential and a modest increase in apoptosis in vitro. The present study extended these findings by (i) investigating the effects of RuIbp on human glioma cell line proliferation in vitro and (ii) investigating the acute and chronic toxicology of the compound in normal Wistar rats. The compound was then tested for its anti-tumour properties by either chronic 14 days intra-peritoneal (IP) administration or chronic Alzet osmotic pump infusion, in the rat C6 orthotopic glioma model in vivo. The IP injection of RuIbp caused a 41 % inhibition of tumour area without significant toxic effects but with an increase in blood neutrophils and monocytes and a decrease in blood lymphocytes. In an attempt to reduce this effect RuIbp was administered by Alzet osmotic pump infusion directly into the tumour at a dose of 15 mg/kg with an infusion rate of 0.5 µL/h for 14 days. The direct infusion of RuIbp caused a 45 % inhibition of tumour area without alterations in differential blood leukocyte counts. These results prove the efficacy of RuIbp in human glioma cell lines in vitro and in an in vivo glioma model and point to its potential as an inhibitor of tumour growth in vivo.

Autophagy and genomic integrity

DNA lesions, constantly produced by endogenous and exogenous sources, activate the DNA damage response (DDR), which involves detection, signaling and repair of the damage. Autophagy, a lysosome-dependent degradation pathway that is activated by stressful situations such as starvation and oxidative stress, regulates cell fate after DNA damage and also has a pivotal role in the maintenance of nuclear and mitochondrial genomic integrity. Here, we review important evidence regarding the role played by autophagy in preventing genomic instability and tumorigenesis, as well as in micronuclei degradation. Several pathways governing autophagy activation after DNA injury and the influence of autophagy upon the processing of genomic lesions are also discussed herein. In this line, the mechanisms by which several proteins participate in both DDR and autophagy, and the importance of this crosstalk in cancer and neurodegeneration will be presented in an integrated fashion. At last, we present a hypothetical model of the role played by autophagy in dictating cell fate after genotoxic stress.

Pharmacodynamic modeling of cell cycle and apoptotic effects of gemcitabine on pancreatic adenocarcinoma cells

PURPOSE

The standard of care for treating patients with pancreatic adenocarcinomas includes gemcitabine (2',2'-difluorodeoxycytidine). Gemcitabine primarily elicits its response by stalling the DNA replication forks of cells in the S phase of the cell cycle. To provide a quantitative framework for characterizing the cell cycle and apoptotic effects of gemcitabine, we developed a pharmacodynamic model in which the activation of cell cycle checkpoints or cell death is dependent on gemcitabine exposure.

METHODS

Three pancreatic adenocarcinoma cell lines (AsPC-1, BxPC-3, and MiaPaca-2) were exposed to varying concentrations (0-100,000 ng/mL) of gemcitabine over a period of 96 h in order to quantify proliferation kinetics and cell distributions among the cell cycle phases. The model assumes that the drug can inhibit cycle-phase transitioning in each of the 3 phases (G1, S, and G2/M) and can cause apoptosis of cells in G1 and G2/M phases. Fitting was performed using the ADAPT5 program.

RESULTS

The time course of gemcitabine effects was well described by the model, and parameters were estimated with good precision. Model predictions and experimental data show that gemcitabine induces cell cycle arrest in the S phase at low concentrations, whereas higher concentrations induce arrest in all cell cycle phases. Furthermore, apoptotic effects of gemcitabine appear to be minimal and take place at later time points.

CONCLUSION

The pharmacodynamic model developed provides a quantitative, mechanistic interpretation of gemcitabine efficacy in 3 pancreatic cancer cell lines, and provides useful insights for rational selection of chemotherapeutic agents for combination therapy.

Investigation of the peak action wavelength of light-activated gene transduction

Light-activated gene transduction (LAGT) is an approach to localize gene therapy via preactivation of cells with UV light, which facilitates transduction by recombinant adeno-associated virus vectors. Prior studies demonstrated that UVC induces LAGT secondary to pyrimidine dimer formation, while UVA induces LAGT secondary to reactive oxygen species (ROS) generation. However, the empirical UVB boundary of these UV effects is unknown. Thus, we aimed to define the action spectra for UV-induced LAGT independent of DNA damage, and determine an optimal wavelength to maximize safety and efficacy. Results: UV at 288, 311 and 320nm produced significant dose-dependent LAGT effects, of which the maximum (800-fold) was observed with 4kJ/m² at 311nm. Consistent with its robust cytotoxicity, 288nm produced significantly high levels of DNA damage at all doses tested, while 311, 320 and 330nm did not generate pyrimidine dimers and produced low levels of DNA damage detected by comet assay. While 288nm failed to induce ROS, the other wavelengths were effective, with the maximum (10-fold) effect observed with 30 kJ/m² at 311nm. An in vivo pilot study assessing 311nm-induced LAGT of rabbit articular chondrocytes demonstrated a significant 6.6-fold (p<0.05) increase in transduction with insignificant cytotoxicity. Conclusion: 311nm was found to be the optimal wavelength for LAGT based on its superior efficacy at the peak dose, and its broad safety range that is remarkably wider than the other UV wavelengths tested.

Functions of MDMX in the modulation of the p53-response

The MDM family proteins MDM2 and MDMX are two critical regulators of the p53 tumor suppressor protein. Expression of both proteins is necessary for allowing the embryonal development by keeping the activity of p53 in check. Upon stresses that need to activate p53 to perform its function as guardian of the genome, p53 has to be liberated from these two inhibitors. In this review, we will discuss the various mechanisms by which MDMX protein levels are downregulated upon various types of stress, including posttranslational modifications of the MDMX protein and the regulation of mdmx mRNA expression, including alternative splicing. In addition, the putative function(s) of the described MDMX splice variants, particularly in tumor development, will be discussed. Lastly, in contrast to common belief, we have recently shown the existence of a p53-MDMX feedback loop, which is important for dampening the p53-response at later phases after genotoxic stress.

Enhancement of temozolomide-induced apoptosis by valproic acid in human glioma cell lines through redox regulation

Temozolomide (TMZ) is an oral alkylating agent that has been widely used in the treatment of refractory glioma, although inherent and acquired resistance to this drug is common. The clinical use of valproic acid (VPA) as an anticonvulsant and mood-stabilizing drug has been reported primarily for the treatment of epilepsy and bipolar disorder and less commonly for major depression. VPA is also used in the treatment of glioma-associated seizures with or without intracranial operation. In this study, we evaluated the potential synergistic effect of TMZ and VPA in human glioma cell lines. Compared with the use of TMZ or VPA alone, concurrent treatment with both drugs synergistically induced apoptosis in U87MG cells as evidenced by p53 and Bax expression, mitochondrial transmembrane potential loss, reactive oxygen species production, and glutathione depletion. This synergistic effect correlated with a decrease in nuclear translocation of the nuclear factor-erythroid 2 p45-related factor and corresponded with reduced heme oxygenase-1 and γ-glutamylcysteine synthetase expression. Pretreatment with N-acetylcysteine partially recovered the apoptotic effect of the TMZ/VPA combination treatment. The same degree of synergism is also seen in p53-mutant Hs683 cells, which indicates that p53 may not play a major role in the increased proapoptotic effect of the TMZ/VPA combination. In conclusion, VPA enhanced the apoptotic effect of TMZ, possibly through a redox regulation mechanism. The TMZ/VPA combination may be effective for treating glioma cancer and may be a powerful agent against malignant glioma. This drug combination should be further explored in the clinical setting.

Pseudoprogression in patients with malignant gliomas treated with concurrent temozolomide and radiotherapy: potential role of p53

We investigated pseudoprogression (psPD) in patients with malignant gliomas treated with radiotherapy (RT) and maintenance temozolomide (TMZ) in terms of incidence, outcomes, and predictive and prognostic factors. We evaluated p53 overexpression by immunohistochemical analysis of thirty-five tumor samples as a predictor for psPD. The time to progression and overall survival were compared between subgroups, psPD versus early progression (ePD) versus nonprogression (nonPD). Eight patients developed psPD among eighteen patients with lesion enlargement at the first MRI scan, and the others were classified as ePD. The remaining stable or improved patients were classified as nonPD. All patients with psPD were alive at last follow-up (median follow-up period was 12 months; range 5.8-58.5 months). Overall survival of psPD patients was significantly higher than ePD patients (P < 0.01). There was no significant survival difference between the psPD group and nonPD group (P = 0.25). Seven (87.5%) of eight tumors with psPD showed p53 overexpression, as compared to 3 (30%) of the ten tumors with ePD (P = 0.03). Our study indicates that psPD following chemoradiotherapy with TMZ is associated with significantly better overall survival compared to that of ePD, and is comparable to nonPD group. Overexpression of p53 was identified as a potential biomarker for predicting the development of psPD.