FLASH X-ray spares intestinal crypts from pyroptosis initiated by cGAS-STING activation upon radioimmunotherapy.

DNA-damaging treatments such as radiotherapy (RT) have become promising to improve the efficacy of immune checkpoint inhibitors by enhancing tumor immunogenicity. However, accompanying treatment-related detrimental events in normal tissues have posed a major obstacle to radioimmunotherapy and present new challenges to the dose delivery mode of clinical RT. In the present study, ultrahigh dose rate FLASH X-ray irradiation was applied to counteract the intestinal toxicity in the radioimmunotherapy. In the context of programmed cell death ligand-1 (PD-L1) blockade, FLASH X-ray minimized mouse enteritis by alleviating CD8+ T cell-mediated deleterious immune response compared with conventional dose rate (CONV) irradiation. Mechanistically, FLASH irradiation was less efficient than CONV X-ray in eliciting cytoplasmic double-stranded DNA (dsDNA) and in activating cyclic GMP-AMP synthase (cGAS) in the intestinal crypts, resulting in the suppression of the cascade feedback consisting of CD8+ T cell chemotaxis and gasdermin E-mediated intestinal pyroptosis in the case of PD-L1 blocking. Meanwhile, FLASH X-ray was as competent as CONV RT in boosting the antitumor immune response initiated by cGAS activation and achieved equal tumor control in metastasis burdens when combined with anti-PD-L1 administration. Together, the present study revealed an encouraging protective effect of FLASH X-ray upon the normal tissue without compromising the systemic antitumor response when combined with immunological checkpoint inhibitors, providing the rationale for testing this combination as a clinical application in radioimmunotherapy.

Suppression of autophagy augments the radiosensitizing effects of STAT3 inhibition on human glioma cells.

Radiotherapy is an essential component of the standard therapy for newly diagnosed glioblastoma. To increase the radiosensitivity of glioma cells is a feasible solution to improve the therapeutic effects. It has been suggested that inhibition of signal transducer and activator of transcription 3 (STAT3) can radiosensitize glioma cells, probably via the activation of mitochondrial apoptotic pathway. In this study, human malignant glioma cells, U251 and A172, were treated with an STAT3 inhibitor, WP1066, or a short hairpin RNA plasmid targeting STAT3 to suppress the activation of STAT3 signaling. The radiosensitizing effects of STAT3 inhibition were confirmed in glioma cells. Intriguingly, combination of ionizing radiation exposure and STAT3 inhibition triggered a pronounced increase of autophagy flux. To explore the role of autophagy, glioma cells were treated with 3-methyladenine or siRNA for autophagy-related gene 5, and it was demonstrated that inhibition of autophagy further strengthened the radiosensitizing effects of STAT3 inhibition. Accordingly, more apoptotic cells were induced by the dual inhibition of autophagy and STAT3 signaling. In conclusion, our data revealed a protective role of autophagy in the radiosensitizing effects of STAT3 inhibition, and inhibition of both autophagy and STAT3 might be a potential therapeutic strategy to increase the radiosensitivity of glioma cells.

Delayed Administration of WP1066, an STAT3 Inhibitor, Ameliorates Radiation-Induced Lung Injury in Mice.

PURPOSE: The present study was designed to investigate the effects of WP1066, a specific inhibitor of STAT3 signaling, on radiation-induced lung injury in mice. METHODS: C57BL/6J mice were subjected to a single thoracic irradiation of 15 Gy X-ray and WP1066 was administrated through intraperitoneal injection. The early and delayed treatment groups were treated with WP1066 during the first 2 weeks and the second 2 weeks, respectively. The therapeutic effects of WP1066 were evaluated by survival analysis, histological examination, and measurement of inflammatory parameters and collagen deposition. The activation of STAT3 pathway was also estimated by immunohistochemical staining and Western blotting. RESULTS: Delayed treatment of WP1066, but not early treatment, prolonged survival time and prevented the development of radiation pneumonitis and the subsequent lung fibrosis in mice. WP1066 treatment also significantly suppressed the activation of STAT3 signaling in the irradiated lung tissues. CONCLUSIONS: The activation of STAT3 pathway might play an important part in the pathogenesis of radiation-induced lung injury. The protective effects of delayed treatment of WP1066 suggested STAT3 signaling could be a therapeutic target for radiation pneumonitis.

Knockdown of miR-210 decreases hypoxic glioma stem cells stemness and radioresistance.

Glioma contains abundant hypoxic regions which provide niches to promote the maintenance and expansion of glioma stem cells (GSCs), which are resistant to conventional therapies and responsible for recurrence. Given the fact that miR-210 plays a vital role in cellular adaption to hypoxia and in stem cell survival and stemness maintenance, strategies correcting the aberrantly expressed miR-210 might open up a new therapeutic avenue to hypoxia GSCs. In the present study, to explore the possibility of miR-210 as an effective therapeutic target to hypoxic GSCs, we employed a lentiviral-mediated anti-sense miR-210 gene transfer technique to knockdown miR-210 expression and analyze phenotypic changes in hypoxic U87s and SHG44s cells. We found that hypoxia led to an increased HIF-2α mRNA expression and miR-210 expression in GSCs. Knockdown of miR-210 decreased neurosphere formation capacity, stem cell marker expression and cell viability, and induced differentiation and G0/G1 arrest in hypoxic GSCs by partially rescued Myc antagonist (MNT) protein expression. Knockdown of MNT could reverse the gene expression changes and the growth inhibition resulting from knockdown of miR-210 in hypoxic GSCs. Moreover, knockdown of miR-210 led to increased apoptotic rate and Caspase-3/7 activity and decreased invasive capacity, reactive oxygen species (ROS) and lactate production and radioresistance in hypoxic GSCs. These findings suggest that miR-210 might be a potential therapeutic target to eliminate GSCs located in hypoxic niches.

Adenovirus-mediated coexpression of DCX and SPARC radiosensitizes human malignant glioma cells.

This study is designed to examine the radiosensitizing effects of coexpression of doublecortin (DCX) and secreted protein and rich in cysteine (SPARC). Previously, we showed that downregulation of SPARC by small interfering RNA increased radioresistance of U-87MG glioma cells. Therefore, overexpression of SPARC might increase radiosensitivity of glioma cells. But SPARC has been shown to promote glioma cell invasion both in vitro and vivo. In order to radiosensitize glioma cells without stimulating invasion, we chose DCX, which is a well-characterized anti-tumor gene, to coexpress with SPARC. An adenovirus-mediated double gene expression system was constructed and applied to U251 and A172 glioma cell lines. Our data showed that coexpression of DCX and SPARC collaboratively diminished radioresistance of glioma cells, interfered with cell cycle turnover and increased irradiation-induced apoptosis. In addition, transwell assay revealed that coexpression was able to counteract the invasion-promoting effects of SPARC, and even inhibited intrinsic invasion, evidenced by less invading cells in double gene overexpressed group than that of control adenovirus-treated group. In conclusion, genetic engineering combining two or more genes might be a more effective method to overcome radioresistance of glioma cells.

Downregulation of miR-210 expression inhibits proliferation, induces apoptosis and enhances radiosensitivity in hypoxic human hepatoma cells in vitro.

Hypoxia is a common feature of solid tumors and an important contributor to tumor radioresistance. miR-210 is the most consistently and robustly induced microRNA under hypoxia in different types of tumor cells and normal cells. In the present study, to explore the feasibility of miR-210 as an effective therapeutic target, lentiviral-mediated anti-sense miR-210 gene transfer technique was employed to downregulate miR-210 expression in hypoxic human hepatoma SMMC-7721, HepG2 and HuH7 cells, and phenotypic changes of which were analyzed. Hypoxia led to an increased hypoxia inducible factor-1α (HIF-1α) and miR-210 expression and cell arrest in the G(0)/G(1) phase in all cell lines. miR-210 downregulation significantly suppressed cell viability, induced cell arrest in the G(0)/G(1) phase, increased apoptotic rate and enhanced radiosensitivity in hypoxic human hepatoma cells. Moreover, apoptosis-inducing factor, mitochondrion-associated, 3 (AIFM3) was identified as a direct target gene of miR-210. AIFM3 downregulation by siRNA attenuated radiation induced apoptosis in miR-210 downregulated hypoxic human hepatoma cells. Taken together, these data suggest that miR-210 might be a potential therapeutic target and specific inhibition of miR-210 expression in combination with radiotherapy might be expected to exert strong anti-tumor effect on hypoxic human hepatoma cells.

NAD+ depletion radiosensitizes 2-DG-treated glioma cells by abolishing metabolic adaptation.

Two-deoxy-d-glucose (2-DG) mediated glucose restriction (GR) has been applied as a potential therapeutic strategy for tumor clinical treatments. However, increasing evidences have indicated that 2-DG alone is inefficient in killing tumor cells, and the effect of 2-DG on modifying tumor radio-responses also remains controversial. In this study, we found that 2-DG triggered metabolic adaption in U87 glioma cells by up-regulating nicotinamide phosphoribosyltransferase (NAMPT) and cellular NAD+ content, which abolished 2-DG-induced potential radiosensitizing effect in glioma cells. Strikingly, NAD+ depletion evoked notable oxidative stress by NADPH reduction and hence re-radiosensitized 2-DG-treated glioma cells. Furthermore, isocitrate dehydrogenase-1 (IDH1) mutant U87 glioma cells with deficiency in the rate-limiting enzyme of Preiss-Handler pathway nicotinate phosphoribosyltransferase (Naprt1) revealed notable 2-DG-induced oxidative stress and radiosensitization. Our findings implied that targeting NAD+ could radiosensitize gliomas with GR, and 2-DG administration could be benefit for tumor patients with IDH1 mutation.

Effects of gamma radiation on bone-marrow stromal cells.

The effects of in vitro irradiation on proliferation and hematopoietic supportive functions of stromal cells were studied. To assess the effects of radiation on stromal cells proliferation, marrow cells were exposed to a single dose of gamma radiation. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that stromal cell proliferation was significantly suppressed after radiation in a dose-dependent manner. Stromal layers obtained from irradiated marrow cells failed to establish adherent layers after 6, 8, or 10 Gy of radiation. To assess the functions of stromal cells that survived radiation, stromal layers derived from irradiated marrow cells were cocultured with freshly isolated autologous hematopoietic cells and assayed for their capacity to support prolonged granulocyte-macrophage progenitors (CFU-GM) production. Stromal layers derived from 2-Gy-irradiated marrow cells resulted in similar CFU-GM production as control cells, while stromal layers derived from 4- to 10-Gy-irradiated marrow cells significantly decreased CFU-GM production. To study the influence of radiation on hematopoietic supportive capacity in established stromal layers, stromal layers generated from non-irradiated marrow cells were irradiated and cocultured with freshly isolated autologous hematopoietic cells. Established stromal layers irradiated up to 10 Gy sustained prolonged CFU-GM production, suggesting that hematopoietic stromal supportive functions remained intact at this dose of radiation. In conclusion, our results indicated that proliferation of stromal cells and bone-marrow stromal layer formation from stromal cells are sensitive to radiation in vitro, while established bone-marrow stromal layer originating from stromal cells is relatively resistant to radiation. Data generated may have implications in future bone-marrow transplantation research.

Biologic characteristics of the side population of human small cell lung cancer cell line H446.

BACKGROUND AND OBJECTIVE: Recently, the theory of cancer stem cells (CSCs) has presented new targets and orientations for tumor therapy. The major difficulties in researching CSCs include their isolation and purification. The aim of this study is to identify and characterize the side population (SP) cells in small cell lung cancer (SCLC) cell line H446, which lays the foundation for the isolation and purification of CSCs. METHODS: Fluorescence-activated cell sorting (FACS) was used to sort SP and non-SP (NSP) cells from H446. Both subgroups were cultivated to survey the capacity to form into suspended tumor cell spheres. Reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR were used to evaluate the expression levels of the mRNA of CD133, ABCG2, and nucleostemin in both subgroups. The capacity of proliferation and the differences in drug resistance of both subgroups and unsorted cells were tested by the MTT method. The differentiation ability of both subgroups was determined by FACS. Proliferation was determined by subcutaneous tumor formation in nude mice. RESULTS: The percent of Hoechst 33342 negative cells was about (5.1 +/- 0.2)% in H446 by fluorescence microscopy. The percent of SP cells was (6.3 +/- 0.1)% by flow cytometry. SP cells had a stronger capability of forming into tumor spheres than NSP cells. The mRNA expression levels of ABCG2, CD133, and nucleostemin in SP cells were 21.60 +/- 0.26, 7.10 +/- 0.14, and 1.02 +/- 0.08 folds higher than that in NSP cells (P < 0.01, P < 0.01, and P > 0.05, respectively). In vivo, SP cells showed better proliferative ability and tougher viability when treated with drugs. SP cells can differentiate into NSP cells, but NSP cells cannot differentiate into SP cells. SP cells had a greater ability to form tumors. CONCLUSION: The H446 cell line contained some SP cells with stem cell properties. CD133 and ABCG2 may be cancer stem cell markers of SCLC.

IDH1-R132H mutation radiosensitizes U87MG glioma cells via epigenetic downregulation of TIGAR.

Isocitrate dehydrogenase 1 (IDH1) is the most frequently mutated gene in World Health Organization grade II-III and secondary glioma. The majority of IDH1 mutation cases involve the substitution from arginine to histidine at codon 132 (IDH1-R132H). Although the oncogenic role of IDH1-R132H has been confirmed, patients with IDH1-R132H brain tumors exhibit a better response to radiotherapy compared with those with wild-type (WT) IDH1. In the present study, the potential mechanism of radiosensitization mediated by IDH1-R132H was investigated by overexpressing IDH1-R132H in U87MG glioma cells. The results demonstrated decreased clonogenic capacity of IDH1-R132H-expressing cells, as well as delayed repair of DNA double-strand breaks compared with IDH1-WT. Data from The Cancer Genome Atlas were analyzed, which demonstrated that the expression of TP53-induced glycolysis and apoptosis regulator (TIGAR) was lower in patients with glioma harboring IDH1 mutations compared with that in patients with IDH1-WT. TIGAR-knockdown increases the radiosensitivity of glioma cells; in U87MG cells, IDH1-R132H suppressed TIGAR expression. Chromatin immunoprecipitation assays revealed increased levels of repressive H3K9me3 markers at the TIGAR promoter in IDH1-R132H compared with IDH1-WT. These data indicated that IDH1-R132H may overcome radioresistance in glioma cells through epigenetic suppression of TIGAR expression. However, these favorable effects were not observed in U87MG glioma stem-like cells. The results of the present study provide an improved understanding of the functionality of IDH1 mutations in glioma cells, which may improve the therapeutic efficacy of radiotherapy.

TIGAR/AP-1 axis accelerates the division of Lgr5- reserve intestinal stem cells to reestablish intestinal architecture after lethal radiation.

During radiologic or nuclear accidents, high-dose ionizing radiation (IR) can cause gastrointestinal syndrome (GIS), a deadly disorder that urgently needs effective therapy. Unfortunately, current treatments based on natural products and antioxidants have shown very limited effects in alleviating deadly GIS. Reserve intestinal stem cells (ISCs) and secretory progenitor cells are both reported to replenish damaged cells and contribute to crypt regeneration. However, the suppressed ß-catenin/c-MYC axis within these slow-cycling cells leads to limited regenerative response to restore intestinal integrity during fatal accidental injury. Current study demonstrates that post-IR overexpression of TIGAR, a critical downstream target of c-MYC in mouse intestine, mounts a hyperplastic response in Bmi1-creERT+ reserve ISCs, and thus rescues mice from lethal IR exposure. Critically, by eliminating damaging reactive oxygen species (ROS) yet retaining the proliferative ROS signals, TIGAR-overexpression enhances the activity of activator protein 1, which is indispensable for initiating reserve-ISC division after lethal radiation. In addition, it is identified that TIGAR-induction exclusively gears the Lgr5- subpopulation of reserve ISCs to regenerate crypts, and intestinal TIGAR-overexpression displays equivalent intestinal reconstruction to reserve-ISC-restricted TIGAR-induction. Our findings imply that precise administrations toward Lgr5- reserve ISCs are promising strategies for unpredictable lethal injury, and TIGAR can be employed as a therapeutic target for unexpected radiation-induced GIS.

Genome-Wide Profiling of the Toxic Effect of Bortezomib on Human Esophageal Carcinoma Epithelial Cells.

OBJECTIVES: Bortezomib has been widely used to treat multiple myeloma and other hematological malignancies. However, not much is known about its effect on solid tumors. The aim of this study was to study the effect of Bortezomib on human esophageal cancer cell lines and investigate the potential target pathways. METHODS: Two human esophageal cancer cell lines, TE-1 and KYSE-150, were used in this study. Cell viability, cell cycle distribution, and apoptosis after Bortezomib treatment was detected by Cell Counting Kit-8, flow cytometry, and Annexin V/propidium iodide staining, respectively. The genes targeted by Bortezomib were analyzed at the messenger RNA level by microarray chips and quantitative real-time polymerase chain reaction. RESULTS: The proliferation of human esophageal cancer cell lines was inhibited by Bortezomib in a dose- and time-dependent manner. Bortezomib treatment led to G2/M arrest and apoptosis. Microarray chips revealed multiple signaling pathways targeted by Bortezomib, including proteasome, endoplasmic reticulum, Wnt-, and calcium-mediated pathway. The expression patterns of 4 representative genes UBD, CUL3, HDAC6, and GADD45A were verified by quantitative real-time polymerase chain reaction and showed consistency with the microarray assay. CONCLUSION: Bortezomib could suppress cell viability, cause G2/M arrest, and induce apoptosis in human esophageal cancer cells, with possible targets including UBD, CUL3, HDAC6, and GADD45A.

Robo1-specific CAR-NK Immunotherapy Enhances Efficacy of 125I Seed Brachytherapy in an Orthotopic Mouse Model of Human Pancreatic Carcinoma.

BACKGROUND/AIM: The aim of the current study was to investigate the synergistic efficacy of Robo1 bichimeric antigen receptor-natural killer cell (BiCAR-NK) immunotherapy and 125I seed brachytherapy in an orthotopic pancreatic cancer mouse model. MATERIALS AND METHODS: The orthotopic pancreatic tumor model was established with human pancreatic cancer BxPC-3 cells expressing red fluorescent protein. The mice were treated with 125I seed implantation alone or the combination of 125I seeds with Robo1-specific CAR-NK cells. To assess tumor inhibition, in vivo fluorescence imaging was conducted. 7 Tesla magnetic resonance (7T-MR) scanning was applied to measure the changes in the metabolic profiles of tumor tissues. RESULTS: Tumor size was significantly reduced in the 125I and 125I +CAR-NK treated group compared to the untreated group (p<0.05). The 125I seed +CAR-NK treated group showed significantly higher tumor reduction than 125I seed treatment alone (p<0.05). T1 diffusion weighted imaging (T1DWI) sequence showed that the tumors of the 125I +BiCAR-NK treated group had a significantly higher grey scale value than the tumors from the untreated control and the group treated with 125I seed alone (p<0.05). CONCLUSION: Robo1 specific CAR-NK immunotherapy enhances efficacy of 125I seed brachytherapy in an orthotopic pancreatic cancer mouse model.

A CRISPR/Cas9-Based Screening for Non-Homologous End Joining Inhibitors Reveals Ouabain and Penfluridol as Radiosensitizers.

Non-homologous end joining (NHEJ) is the major pathway responsible for the repair of ionizing radiation (IR)-induced DNA double-strand breaks (DSB), and correspondingly regulates the cellular response to IR. Identification of NHEJ inhibitors could substantially enhance the tumor radiosensitivity and improve the therapeutic efficiency of radiotherapy. In this study, we demonstrated a screening for NHEJ inhibitors using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and high-resolution melting (HRM) analysis. Because NHEJ is regarded as an error-prone mechanism, the NHEJ-mediated ligation of the site-specific DSB induced by Cas9 nuclease would eventually cause the mutation of the targeted sequence. Then, HRM analysis, a reliable and rapid assay for detecting sequence variation, was performed to evaluate the mutation efficiency of the targeted site. Validating analysis confirmed the NHEJ activities were positively correlated with the mutation frequencies. Next, an approved drug library containing 1,540 compounds was interrogated by using this screening strategy. Our results identified ouabain, a cardiotonic agent, and penfluridol, an antipsychotic agent, have the capacity to restrain NHEJ activity. Further experiments in vitro revealed the radiosensitizing effects of these compounds. Overall, we presented a cell-based screening for NHEJ inhibitors, which could promote the discovery of novel radiosensitizers. Mol Cancer Ther; 17(2); 419-31. ©2017 AACRSee all articles in this MCT Focus section, "Developmental Therapeutics in Radiation Oncology."

Radiosensitivity enhancement by combined treatment of nimotuzumab and celecoxib on nasopharyngeal carcinoma cells.

INTRODUCTION: In this study, the radiation-enhancing effects of combined treatment with nimotuzumab, a humanized EGFR-blocking antibody, and celecoxib, a COX-2 selective inhibitor, in human nasopharyngeal carcinoma (NPC) cells were investigated. MATERIALS AND METHODS: 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide and clonogenic survival assays were done to evaluate the combined cytotoxic and radiosensitizing effects of nimotuzumab or celecoxib or the combination on CNE1 and CNE2 cells. Western blot analysis was performed to identify the effect of nimotuzumab and/or celecoxib with or without irradiation on the cytoplasmic and nuclear EGFR signaling pathways in CNE2 cells. RESULTS: Our results demonstrated that concurrent administration of nimotuzumab and celecoxib cooperatively enhanced the cytotoxicity and radiosensitivity of CNE2 cells but not CNE1 cells. The combination of both drugs with or without irradiation also cooperatively inhibited cytoplasmic and nuclear EGFR signaling pathways in CNE2 cells. CONCLUSION: Our results suggest a promising approach for the treatment of poorly differentiated NPC.

Quantitative assessment of HR and NHEJ activities via CRISPR/Cas9-induced oligodeoxynucleotide-mediated DSB repair.

Homologous recombination (HR) and non-homologous end joining (NHEJ) are the two major mechanisms for the repair of DNA double-strand breaks (DSBs) in eukaryotic cells. Previously, we designed an assay for detecting NHEJ activity by using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system, however, this approach cannot be used to predict the activity of HR repair. Hence, we developed a novel method that is capable of quantitatively measuring both HR and NHEJ activities via CRISPR/Cas9-induced oligodeoxynucleotide (ODN)-mediated DSB repair. In the present experimental procedures, the CRISPR/Cas9 plasmid was cotransfected with single-stranded ODN (ssODN) or blunt-ended double-stranded ODN (dsODN), both of which harbored a unique marker sequence. After the induction of site-specific DSBs by CRISPR/Cas9 system, the ssODN, functioned as the donor template for HR repair, could insert the marker sequence into the DSB sites, while the dsODN was embedded in the DSB sites through NHEJ pathway. Next, by means of PCR analysis using a specific primer for the marker sequence and the primers that flank the DSB sites, the relative amount of integrated marker sequence in the genomic DNA could be quantitatively determined. The correlation between the marker sequence abundance and the HR and NHEJ activities was confirmed by using the selective HR and NHEJ inhibitors. This accessible and rapid quantitative assay for HR and NHEJ activities might be useful for the future research of the DSB repair mechanisms.

TIGAR knockdown radiosensitizes TrxR1-overexpressing glioma in vitro and in vivo via inhibiting Trx1 nuclear transport.

The up-regulation of thioredoxin reductase-1 (TrxR1) is detected in more than half of gliomas, which is significantly associated with increased malignancy grade and recurrence rate. The biological functions of NADPH-dependent TrxR1 are mainly associated with reduced thioredoxin-1 (Trx1) which plays critical roles in cellular redox signaling and tumour radio-resistance. Our previous work has proved that TP53 induced glycolysis and apoptosis regulator (TIGAR) knockdown could notably radiosensitize glioma cells. However, whether TrxR1-overexpressing glioma cells could be re-radiosensitized by TIGAR silence is still far from clear. In the present study, TrxR1 was stably over-expressed in U-87MG and T98G glioma cells. Both in vitro and in vivo data demonstrated that the radiosensitivity of glioma cells was considerably diminished by TrxR1 overexpression. TIGAR abrogation was able to radiosensitize TrxR1-overexpressing gliomas by inhibiting IR-induced Trx1 nuclear transport. Post-radiotherapy, TIGAR low-expression predicted significant longer survival time for animals suffering from TrxR1-overexpessing xenografts, which suggested that TIGAR abrogation might be a promising strategy for radiosensitizing TrxR1-overexpressing glial tumours.

Induction chemotherapy followed by concurrent chemoradiation and nimotuzumab for locoregionally advanced nasopharyngeal carcinoma: preliminary results from a phase II clinical trial.

Overexpression of epidermal growth factor receptor can be found in more than 80% of patients with locoregionally advanced nasopharyngeal carcinoma and is associated with shorter survival. In this work, we evaluated the feasibility of adding nimotuzumab to chemoradiation in locoregionally advanced nasopharyngeal carcinoma. Twenty-three patients with clinically staged T3-4 or any node-positive disease were enrolled. They were scheduled to receive one cycle of induction chemotherapy followed by intensity-modulated radiotherapy, weekly administration of nimotuzumab and concurrent chemotherapy. Results showed that all patients received a full course of radiotherapy, 19(82.6%)patients completed the scheduled neoadjuvant and concurrent chemotherapy, and 22(95.7%) patients received ≥6 weeks of nimotuzumab. During the period of concurrent chemoradiation and nimotuzumab, grade 3-4 toxicities occurred in 14(60.9%) patients: 8 (34.8%) had grade 3-4 oral mucositis, 6(26.1%) had grade 3 neutropenia, and 1(4.3%) had grade 3 dermatitis. No acne-like rash was observed. With a median follow-up of 24.1 months, the 2-year progression-free survival and overall survival were 83.5% and 95.0%, respectively. In conclusion, concurrent administration of chemoradiation and nimotuzumab was well-tolerated with good compliance. Preliminary clinical outcome data appear encouraging with favorable normal tissue toxicity results comparing with historical data of concurrent chemoradiation plus cetuximab.

MicroRNA-153/Nrf-2/GPx1 pathway regulates radiosensitivity and stemness of glioma stem cells via reactive oxygen species.

Glioma stem cells (GSCs) exhibit stem cell properties and high resistance to radiotherapy. The main aim of our study was to determine the roles of ROS in radioresistance and stemness of GSCs. We found that microRNA (miR)-153 was down-regulated and its target gene nuclear factor-erythroid 2-related factor-2 (Nrf-2) was up-regulated in GSCs compared with that of non-GSCs glioma cells. The enhanced Nrf-2 expression increased glutathione peroxidase 1 (GPx1) transcription and decreased ROS level leading to radioresistance of GSCs. MiR-153 overexpression resulted in increased ROS production and radiosensitization of GSCs. Moreover, miR-153 overexpression led to decreased neurosphere formation capacity and stem cell marker expression, and induced differentiation through ROS-mediated activation of p38 MAPK in GSCs. Nrf-2 overexpression rescued the decreased stemness and radioresistance resulting from miR-153 overexpression in GSCs. In addition, miR-153 overexpression reduced tumorigenic capacity of GSCs and increased survival in mice bearing human GSCs. These findings demonstrated that miR-153 overexpression decreased radioresistance and stemness of GSCs through targeting Nrf-2/GPx1/ROS pathway.