Polarization of macrophages towards M1 phenotype by a combination of 2-deoxy-d-glucose and radiation: Implications for tumor therapy

2-Deoxy-d-glucose (2-DG) has been found to enhance the cytotoxicity of ionizing radiation and chemotherapeutic drugs in several tumor cell lines in vitro. Systemic administration of 2-DG together with localized irradiation of the tumor leads to tumor regression and cure (disease free survival), which correlate with the differential levels of anti-tumor immunity observed in Ehrlich ascites tumor (EAT) bearing mice. Macrophages being a major player of the innate immune system, we investigated the activation status of splenic macrophages during radio-sensitization of EAT in mice as well as in peritoneal macrophages ex vivo and macrophagic cell line (Raw 264.7) in vitro. Results suggest that under in vivo conditions, the combined treatment (2-DG+radiation) restores the M1 phenotype in spleen that correlated with the tumor response. However, 2-DG neither induced significant cytotoxicity nor enhanced radiation-induced cell death in peritoneal macrophages and the macrophage cell line (Raw 264.7). Further, increased arborization and enhanced functional status (expression of MHC class II, CD80, CD86 and phagocytosis) were observed after the combined treatment. Besides this activation, the combined treatment also skewed the macrophages towards M1 phenotype as evidenced by the enhanced secretion of IL-12, IL-2, TNF-α and IFN-γ. These observations suggest that 2-DG not only preserves the survival of normal macrophages during irradiation, but also activates macrophages by polarizing towards M1 phenotype, which is known to be tumoricidal in nature. This study for the first time sheds light on a potential antitumor immune activation by 2-DG involving macrophagic stimulation during in vivo radio-sensitization of tumors, besides the other known antitumor effects of this glucose analogue.

Hyperbaric oxygen and radiation therapy: a review

About 5% of cancer patients treated with radiotherapy will have severe late-onset toxicity. Hyperbaric oxygen therapy (HBOT) has been used as a treatment for radiation injuries for decades, with many publications presenting data from small series or individual cases. Moreover, we know that the hypoxic areas of tumours are more resistant to radiation. HBOT increases the oxygen tension in tissues and, theoretically, it should enhance the efficiency of radiotherapy. To better understand how HBOT works, we carried out this bibliographic review. We found Grade B and C evidence that at pressures exceeding 2 absolute atmospheres (ata), HBOT reduced late-onset radiation injuries to the head and neck, bone, prostate and bladder. It also appeared to prevent osteoradionecrosis after exodontia in irradiated areas. Finally, HBOT at 2 ata increased the effectiveness of radiation in head and neck tumours and achieved promising results in the local control of high-grade gliomas.

Upregulation of NRF2 through autophagy/ERK 1/2 ameliorates ionizing radiation induced cell death of human osteosarcoma U-2 OS

The antioxidative response mediated by transcription factor NRF2 is thought to be a pivotal cellular defense system against various extrinsic stresses. It has been reported that activation of the NRF2 pathway confers cells with resistance to ionizing radiation-induced damage. However, the underlying mechanism remains largely unknown. In the current research, it was found that α-particle radiation has the ability to stimulate NRF2 expression in human osteosarcoma U-2 OS cells. Knockdown of cellular NRF2 level by shRNA-mediated gene silencing decreased the survival rate, increased the micronucleus formation rate and apoptosis rate in irradiated cells. Consistently, knockdown of NRF2 resulted in decreased expression of p65 and Bcl-2, and increased expression of p53 and Bax. Besides, it was observed that increased expression of NRF2 was partially dependent on radiation induced phosphorylation of ERK 1/2. Further results showed that radiation promoted autophagy flux which leads to the enhanced phosphorylation of ERK 1/2, as evidenced by the resultls that knockdown of ATG5 (Autophagy protein 5) gene by shRNA suppressed both radiation induced ERK 1/2 phosphorylation and NRF2 upregulation. Based on these results, it is proposed that attenuation of NRF2 antioxidative pathway can sensitize U-2 OS cells to radiation, where NRF2 antioxidative response is regulated by autophagy mediated activation of ERK 1/2 kinases.

Nattokinase-Mediated Regulation of Tumor Physical Microenvironment to Enhance Chemotherapy, Radiotherapy, and CAR-T Therapy of Solid Tumor

The therapy of solid tumors is always hampered by the intrinsic tumor physical microenvironment (TPME) featured with compact and rigid extracellular matrix (ECM) microstructures. Herein, we introduce nattokinase (NKase), a thrombolytic healthcare drug, to comprehensively regulate the TPME for versatile enhancement of various therapy modalities. Intratumoral injection of NKase not only degrades the major ECM component fibronectin but also inhibits cancer-associated fibroblasts (CAFs) in generating fibrosis, resulting in decreased tumor stiffness, enhanced perfusion, and hypoxia alleviation. The NKase-mediated regulation of the TPME significantly promotes the tumoral accumulation of therapeutic agents, leading to efficient chemotherapy without inducing side effects. Additionally, the enhancement of tumor radiotherapy based on radiosensitizers was also achieved by the pretreatment of intratumorally injected NKase, which could be ascribed to the elevated oxygen saturation level in NKase-treated tumors. Moreover, a xenografted human breast MDB-MA-231 tumor model is established to evaluate the influence of NKase on chimeric antigen receptor (CAR)-T cell therapy, illustrating that the pretreatment of NKase could boost the infiltration of CAR-T cells into tumors and thus be a benefit for tumor inhibition. These findings demonstrate the great promise of the NKase-regulated TPME as a translational strategy for universal enhancement of therapeutic efficacy in solid tumors by various treatments.

Pre-treatment with Bifidobacterium infantis and its specific antibodies enhance targeted radiosensitization in a murine model for lung cancer

PURPOSE

The hypoxic microenvironments of solid tumours are complex and reduce the susceptibility of cancer cells to chemo- and radiotherapy. Conventional radiosensitisers have poor specificity, unsatisfactory therapeutic effects, and significant side effects. Anaerobic bacteria colonise and destroy hypoxic areas of the tumour and consequently enhance the effects of radiation.

METHODS

In this study, we treated a Lewis lung carcinoma transplant mouse model with Bifidobacterium infantis (Bi) combined with its specific monoclonal antibody (mAb) and radiotherapy (RT) to investigate its ability to radiosensitise the tumour. The tumour metabolism and hypoxia in the tumour tissue were monitored by micro-¹⁸F-FDG and ¹⁸F-FMISO PET/CT imaging. Immunohistochemistry was used to detect phosphorylated histone (γ-H2AX), proliferation (Ki-67), platelet endothelial cell adhesion molecules (CD31), tumour necrosis factor-α (TNF-α), hypoxia-inducible factor-1α (HIF-1α), and glucose transporter 1 (Glut-1) levels.

RESULTS

Tumour growth was slowed and survival time was markedly prolonged in mice subjected to the combination of B. infantis, specific antibody, and radiotherapy. Levels of HIF-1α, Glut-1, Ki-67, and CD31 expression, as well as uptake of FDG and FMISO, were the lowest in the combination-treated mice. In contrast, γ-H2AX and TNF-α expression levels were elevated and hypoxia in tumour tissue was reduced compared with controls.

CONCLUSION

In conclusion, our data indicated that the curative effect of radiotherapy for lung cancer was enhanced by pre-treating mice with a combination of B. infantis and its specific monoclonal antibody.

Theranostic magnetic nanoparticles enhance DNA damage and mitigate doxorubicin-induced cardio-toxicity for effective multi-modal tumor therapy

The chemo-therapeutic efficacy of Doxorubicin (Dox), a potent anti-cancer drug used in the treatment of several solid tumors, is severely compromised by its cardio-toxicity. To overcome this shortcoming and exploit the utmost theranostic potential of nano-formulations, magnetic nanoparticles co-encapsulated with Dox and indocyanine green (ICG) in a liposomal carrier and tagged with cyclic RGD peptide were rationally designed and synthesized. These magneto-liposomes (T-LMD) showed αvβ3-integrin receptor targeting and higher cyto-toxicity in several cancer cell lines (i.e. lung, breast, skin, brain and liver cancer) in combination with or without gamma radiation or magnetic hyperthermia therapy as compared to clinical liposomal nano-formulation of Dox (Lippod™). Mechanism of chemo-radio-sensitization was found to involve activation of JNK mediated pro-apoptotic signaling axis and delayed repair of DNA double strand breaks. Real time imaging of ICG labeled T-LMD suggested ~6-18 fold higher tumor accumulation of T-LMD as compared to off-target organs (kidney, liver, spleen, intestine, lungs and heart) and resulted in its higher combinatorial (chemo-radio-hyperthermia) tumor therapy efficacy as compared to Lippod™. Moreover, T-LMD showed insignificant toxicity to the heart tissue as suggested by serum levels of CK-MB, histo-pathological analysis, anti-oxidant enzyme activities (Catalase and GST) and markers of cardiac fibrosis, suggesting its potential for targeted multi-modal therapy of cancer.

Development of new thieno[2,3-d]pyrimidines as dual EGFR and STAT3 inhibitors endowed with anticancer and pro-apoptotic activities

In part due to the resilience of cellular feedback pathways that develop therapeutic resistance to targeting the EGFR alone, using EGFR inhibitors alone was demonstrated to be unsuccessful in clinical trials. The over-activation of the signal transducer/activator of transcription 3 (STAT3) during the administration of an EGFR inhibitor is expected to play a substantial part in the failure and resistance of EGFR inhibitor treatment. Therein, we proposed a hypothesis that induced STAT3-mediated resistance to EGFR inhibition therapy could be addressed by a dual inhibition of EGFR and STAT3 method. To this end, we tried to discover new thieno[2,3-d]pyrimidine derivatives "5a-o". Results from the screening on A549 and MCF7 cancer cell lines revealed that compounds 5j and 5k showed two-digit nanomolar with appropriate safety towards the WI-38 cell line. The best molecules, 5j and 5k, were subjected to γ-radiation, and their cytotoxic efficacy didn't change after irradiation, demonstrating that not having to use it avoided its side effects. Compounds 5j and 5k demonstrated the highest inhibition when their potency was tested as dual inhibitors on EGFR 67 and 41 nM, respectively, and STAT3 5.52 and 3.34 nM, respectively, proved with in silico molecular docking and dynamic simulation. In light of the results presented above, the capacity of both powerful compounds to alter the cell cycle and initiate the apoptotic process in breast cancer MCF7 cells was investigated. Caspase-8, Bcl-2, Bax and Caspase-9 apoptotic indicators were studied.

Pharmacological targeting of differential DNA repair, radio-sensitizes WRN-deficient cancer cells in vitro and in vivo

Werner (WRN) expression is epigenetically downregulated in various tumors. It is imperative to understand differential repair process in WRN-proficient and WRN-deficient cancers to find pharmacological targets for radio-sensitization of WRN-deficient cancer. In the current investigation, we showed that pharmacological inhibition of CHK1 mediated homologous recombination repair (HRR), but not non-homologous end joining (NHEJ) repair, can causes hyper-radiosensitization of WRN-deficient cancers. This was confirmed in cancer cell lines of different tissue origin (osteosarcoma, colon adenocarcinoma and melanoma) with WRN silencing and overexpression. We established that WRN-depleted cells are dependent on a critical but compromised CHK1-mediated HRR-pathway for repairing ionizing radiation (IR) induced DSBs for their survival. Mechanistically, we unraveled a new finding that the MRE11, CTIP and WRN proteins are largely responsible for resections of late and persistent DSBs. In response to IR-treatment, MRE11 and CTIP-positively and WRN-negatively regulate p38-MAPK reactivation in a CHK1-dependent manner. A degradation resistant WRN protein, mutated at serine 1141, abrogates p38-MAPK activation. We also showed that CHK1-p38-MAPK axis plays important role in RAD51 mediated HRR in WRN-silenced cells. Like CHK1 inhibition, pharmacological-inhibition of p38-MAPK also hyper-radiosensitizes WRN-depleted cells by targeting HR-pathway. Combination treatment of CHK1-inhibitor (currently under various clinical trials) and IR exhibited a strong synergy against WRN-deficient melanoma tumor in vivo. Taken together, our findings suggest that pharmacological targeting of CHK1-p38-MAPK mediated HRR is an attractive strategy for enhancing therapeutic response of radiation treatment of cancer.

The role of bacteria and its derived biomaterials in cancer radiotherapy

Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics. It has made significant progress in breaking the limitations of monotherapy and effectively eradicating tumors, especially when combined with traditional therapy, such as radiotherapy. According to their different biological characteristics, bacteria and their derivatives can not only improve the sensitivity of tumor radiotherapy but also protect normal tissues. Moreover, genetically engineered bacteria and bacteria-based biomaterials have further expanded the scope of their applications in radiotherapy. In this review, we have summarized relevant researches on the application of bacteria and its derivatives in radiotherapy in recent years, expounding that the bacteria, bacterial derivatives and bacteria-based biomaterials can not only directly enhance radiotherapy but also improve the anti-tumor effect by improving the tumor microenvironment (TME) and immune effects. Furthermore, some probiotics can also protect normal tissues and organs such as intestines from radiation via anti-inflammatory, anti-oxidation and apoptosis inhibition. In conclusion, the prospect of bacteria in radiotherapy will be very extensive, but its biological safety and mechanism need to be further evaluated and studied.

The effect of iodine-131 beta-particles in combination with A-966492 and Topotecan on radio-sensitization of glioblastoma: An in-vitro study

Glioblastoma tumors are resistant to radiotherapy, and the need for drugs to induce radio-sensitization in tumor cells has always been a challenge. Besides, radiotherapy using targeted radionuclide would be effective even for resistant tumors. It has been shown topoisomerase I and poly (ADP-ribose) polymerase (PARP) enzymes have critical roles in the repair process of DNA injury in cells. Therefore, the inhibition of the activity of these enzymes can halt this process and result in the accumulation of damaged DNA in cells and the induction of cell death in tumors. In the present research, the impact of beta-particles of iodine-131 in combination with Topotecan (TPT), as the inhibitor of topoisomerase I, and A-966492, as the inhibitor of the PARP enzyme on the possible increase of radio-sensitivity of glioblastoma cells was assessed. For this purpose, a human glioblastoma cell line, U87MG, was cultured in flasks coated with Poly-Hema to achieve 300 μm-diameter spheroids. Then, nontoxic concentrations of A-966492 and TPT were applied in the cell culture media. The viability of the cells treated with iodine131 in combination with A-966492 and TPT was determined by the clonogenic assay. The expression rate of gamma-H2AX, as a biomarker of DNA double-strand breaks, was analyzed using immunofluorescence microscopy to unravel the effect of TPT, A-966492 (1 μM), and radiation on the cell death induction. The combination of each TPT or A-966492 with radiation resulted in the increased rate of cell death, and the ratios of sensitizer enhancement at 50% survival (SER50) were elevated by 1.45 and 1.25, respectively. Chemo- and radio-sensitization were promoted when iodine-131 was combined with A-966492 and TPT, with the SER50 of 1.68. Also, the expression of γ-H2AX was significantly increased in cells treated with A-966492 and TPT combined with radiation. The results demonstrated that iodine-131, in combination with A-966492 and TPT, had marked effects on radio-sensitizing and can be used as a targeted radionuclide for targeting radiotherapy in combination with topoisomerase I and PARP inhibitors to enhance radiotherapy in clinics.

Main Approaches to Enhance Radiosensitization in Cancer Cells by Nanoparticles: A Systematic Review

In recent years, high atomic number nanoparticles (NPs) have emerged as promising radio-enhancer agents for cancer radiation therapy due to their unique properties. Multi-disciplinary studies have demonstrated the potential of NPs-based radio-sensitizers to improve cancer therapy and tumor control at cellular and molecular levels. However, studies have shown that the dose enhancement effect of the NPs depends on the beam energy, NPs type, NPs size, NPs concentration, cell lines, and NPs delivery system. It has been believed that radiation dose enhancement of NPs is due to the three main mechanisms, but the results of some simulation studies failed to comply well with the experimental findings. Thus, this study aimed to quantitatively evaluate the physical, chemical, and biological factors of the NPs. An organized search of PubMed/Medline, Embase, ProQuest, Scopus, Cochrane and Google Scholar was performed. In total, 77 articles were thoroughly reviewed and analyzed. The studies investigated 44 different cell lines through 70 in-vitro and 4 in-vivo studies. A total of 32 different types of single or core-shell NPs in different sizes and concentrations have been used in the studies.

Effects of FGFR inhibitors TKI258, BGJ398 and AZD4547 on breast cancer cells in 2D, 3D and tissue explant cultures

Purpose

Fibroblast growth factor receptors (FGFR) and pathways are important players in breast cancer (BC) development. They are commonly altered, and BCs exhibiting FGFR gene amplification are currently being studied for drug development. Here, we aimed to compare the effects of three FGFR inhibitors (FGFRis), i.e., non-selective TKI258 and selective BGJ398 and AZD4547, on different BC-derived cell lines (BCCs) and primary tissues.

Methods

The human BCCs MCF-7 and MDA-MB-231(SA) (wild-type FGFR) and MFM223 (amplified FGFR1 and FGFR2) were analyzed for FGFR expression using qRT-PCR, and the effects of FGFRis on FGFR signaling by Western blotting. The effects of FGFRis on proliferation, viability, migration and invasion of BCCs were assessed in 2D cultures using live-cell imaging, and in 3D cultures using phenotypic analysis of organoids. To study radio-sensitization, FGFRi treatment was combined with irradiation. Patient-derived BC samples were treated with FGFRis in explant cultures and immunostained for Ki67 and cleaved caspase 3.

Results

We found that all FGFRis tested decreased the growth and viability of BC cells in 2D and 3D cultures. BGJ398 and AZD4547 were found to be potent at low concentrations in FGFR-amplified MFM233 cells, whereas higher concentrations were required in non-amplified MCF7 and MDA-MB-231(SA) cells. TKI258 inhibited the migration and invasion, whereas BGJ398 and AZD4547 only inhibited the invasion of MDA-MB-231(SA) cells. FGFRi treatment of MCF7 and MFM223 cells enhanced the inhibitory effect of radiotherapy, but this effect was not observed in MDA-MB-231(SA) cells. FGFRi-treated primary BC explants with moderate FGFR levels showed a tendency towards decreased proliferation and increased apoptosis.

Conclusions

Our results indicate that, besides targeting FGFR-amplified BCs with selective FGFRis, also BCs without FGFR amplification/activation may benefit from FGFRi-treatment. Combination with other treatment modalities, such as radiotherapy, may allow the use of FGFRis at relatively low concentrations and, thereby, contribute to better BC treatment outcomes.

Supplementary Information

The online version of this article (10.1007/s13402-020-00562-0) contains supplementary material, which is available to authorized users.

Radio-sensitization of head and neck cancer cells by a combination of poly(I:C) and cisplatin through downregulation of survivin and c-IAP2

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers. Concurrent radio-chemotherapy is the standard of care for advanced tumors. However, there is a need for more efficient regimens with less side effects resulting from high doses. Therefore, we set out to explore the therapeutic potential of ternary combinations by bringing together irradiation, cis-platinum and a TLR3 agonist, poly(I:C), with the aim to reduce the dosage of each treatment. This approach is based on our previous work, which revealed a selective cytotoxic effect of TLR3 agonists against malignant cells when combined with other anti-neoplastic agents.

METHODS

We explored the survival of HNSCC-derived cells (Detroit 562, FaDu, SQ20B and Cal27) using MTT and caspase 3/7 activation assays. The radio-sensitization effects of poly(I:C) and cisplatin were assessed using Western blotting, cell cycle progression, ROS formation and qRT-PCR assays.

RESULTS

We found that the combination of poly(I:C) and cisplatin downregulated c-IAP2 and survivin expression, reduced cell survival, induced anti-apoptotic gene expression and apoptosis, increased ROS formation and induced G2/M cell cycle arrest in the HNSCC-derived cells tested.

CONCLUSIONS

Our results indicate that a combined poly(I:C) and cisplatin treatment reduces the survival and induces the radio-sensitivity of HNSCC-derived cells, thus providing a rationale for the development of novel strategies for the treatment of head and neck cancer.

Amygdalin-folic acid-nanoparticles inhibit the proliferation of breast cancer and enhance the effect of radiotherapy through the modulation of tumor-promoting factors/ immunosuppressive modulators in vitro

INTRODUCTION

Breast cancer (BC) cells often develop multiple mechanisms of chemo- and radio-resistance during tumor progression, which is the major reason for the failure of breast cancer therapy. Targeted nanomedicines have tremendous therapeutic potential in BC treatment over their free drug counterparts. Searching for chemo- and radio-sensitizers to overcome such resistance is therefore urgently required. The goal of this study is to evaluate and compare the radio-sensitizer efficacy of amygdalin-folic acid nanoparticles (Amy-F) on MCF-7 and MDA-MB-231 cells.

MATERIALS AND METHODS

The effects of Amy-F on MCF-7 and MDA-MB-231 cell proliferation and IC50 were assessed using MTT assay. The expression of proteins involved in several mechanisms induced by Amy-F in MCF-7 and MDA-MB-231 cells, including growth inhibition, apoptosis, tumor growth regulators, immuno-modulators, and radio-sensitizing activities were evaluated via flow cytometry and ELISA assay.

RESULTS

Nanoparticles demonstrated sustained Amy-F release properties and apparent selectivity towards BC cells. Cell-based assays revealed that Amy-F markedly suppresses cancer cell growth and improves radiotherapy (RT) through inducing cell cycle arrest (G1 and sub-G1), and increases apoptosis as well as reduces the proliferation of BC by down-regulating mitogen-activated protein kinases (MAPK/P38), iron level (Fe), nitric oxide (NO), and up-regulating the reactive oxygen species level (ROS). Amy-F has also been shown to suppress the expression of the cluster of differentiation (CD4 and CD80), and interfere with the Transforming growth factor beta (TGF- β)/Interferon-gamma (INF-g)/Interleukin-2 (IL-2)/Interleukin-6 (IL-6)/Vascular endothelial growth factor (VEGF) induced suppression in its signaling hub, while up-regulating natural killer group 2D receptor (NKG2D) and CD8 expression.

CONCLUSIONS

Collectively, the novel Amy-F either alone or in combination with RT abrogated BC proliferation.

The dependence of radio-sensitization efficiency on mitochondrial targeting with NaGdF4:Yb,Er nanoparticles

Radio-sensitization is highly desired to reduce side-effect of the harsh dose of radiation therapy (RT), for which nanoparticles with high atomic number elements provide a promising tool. However, insufficient knowledge on utilizing the interaction between nanoparticles and cancerous cells hampers the improvement of therapeutic outcome. We herein employed NaGdF₄:Yb,Er nano-crystals as the sensitizer, and modified them with a tumor targeting agent and a mitochondria targeting moiety, separately and jointly, to achieve varied extent of mitochondrial accumulation. We observed that NaGdF₄:Yb,Er nano-crystal, even unmodified with targeting ligands, is effective for radio-sensitization. Furthermore, the extent of mitochondrial targeting was responsible for sensitization efficiency both in vitro and in vitro. By RNA sequencing technique, the result was ascribed to the reactive oxygen species (ROS) mediated TNF-JNK pathway and cell cycle arrest besides breaking DNA, in contrast to only DNA damage only with those untargeted nanoparticles. Our work indicated that ROS generated by the irradiation can be utilized by activating an alternative apoptotic pathway with mitochondrial targeting nanoparticles, and therefore may suggest an approach for the enhancement of radio-sensitization. STATEMENT OF SIGNIFICANCE: Radiosensitization by nanoparticles could reduce the burden of cancer due to lowering the dose of radiation therapy and reducing side-effect. How to fully utilize the interactions of irradiation-nanoparticles-biotissues remains a challenge for improving the outcome of radiosensitization. In this manuscript, by modifying tumor-targeting and mitochondria-targeting ligands on nanoparticles, separately and jointly, we demonstrated that the radiosensitization efficiency of NaGdF₄:Yb,Er nanoparticle depends on the extent of accumulation near mitochondria. By RNA-seq technique, the RT sensitization with mitochondrial targeting was ascribed to ROS-mediated TNF-JNK pathway and cell cycle arrest, in contrast to only DNA breaks with untargeted nanoparticles. The results suggested a strategy for better utilization of the energy of therapeutic irradiation and demonstrate that subcellular targeting is a potent factor for designing nanoparticulate radiosensitizers.

Luteolin inhibits angiogenesis and enhances radiotherapy sensitivity of laryngeal cancer via downregulating Integrin β1

AIM

To demonstrate the role and mechanism of luteolin in radio-sensitization and angiogenesis of laryngeal cancer.

METHODS

Firstly, we analyzed the cytotoxicity of Luteolin and radiation sensitive cytotoxicity through CCK8, and selected subsequent radiation doses and Luteolin concentrations. Next, we further analyzed the effects of Luteolin on radiation sensitivity and neovascularization of laryngeal cancer, and conducted CCK8, plate cloning, and angiogenesis experiments, respectively. At the same time, the effects of individual treatment and combination treatment on the expression of Integrin β1 and VEGFA were analyzed through immunofluorescence analysis. We also analyzed the regulation of Integrin β1 protein expression by Luteolin through Western blot. To investigate the mechanism of Integrin β1, we transfected overexpressed and silenced Integrin β1 vectors and analyzed the role of Integrin β1 in Luteolin enhancing radiation sensitivity of laryngeal cancer by repeating the above experiments. We have also constructed an in vivo subcutaneous tumor transplantation model to further validate the cell experimental results. The expression of Integrin, KI67, VEGFA, and CD31 was analyzed through Western blot and immunohistochemistry experiments.

RESULTS

Radiation inhibited cell proliferation and decreased Integrin β1 expression, and increased the radiosensitivity through inhibiting cell proliferation, and inhibit angiogenesis during radiation. Overexpression of Integrin β1 weakened radiotherapy sensitivity on the basis of cells treated with combined administration. Integrin β1 is considered as the downstream molecule of luteolin, participating in radiosensitivity of luteolin to FaDu cells. Animal experiments also demonstrated that luteolin strengthened tumor suppression and anti-angiogenesis during radiation via Integrin β1.

CONCLUSION

In summary, our results manifested that radio-sensitivity effect of luteolin depended on downregulating Integrin β1 in laryngocarcinoma.

The COX-2 inhibitor NS398 selectively sensitizes hypoxic HeLa cells to ionising radiation by mechanisms both dependent and independent of COX-2

It is widely accepted that the hypoxic nature of solid tumors contribute to their resistance to radiation therapy. There is increasing evidence that cyclooxygenase-2 (COX-2) contributes to increased resistance of tumors to radiation therapy. Several studies demonstrate that combination of COX-2 selective inhibitors with radiation therapy selectively enhances radio responsiveness of tumor cells. However, the majority of these studies utilised suprapharmacological concentrations under normoxic conditions only. Furthermore, the mechanism by which these agents act remain largely unclear. Therefore, the aim of this study was to determine the impact of COX-2 selective inhibitors on both normoxic and hypoxic radiosensitivity in vitro and the mechanisms underlying this. Because of the close, reciprocal relationship between COX-2 and p53 we investigated their contribution to radioresistance. To achieve this we exposed HeLa, MCF-7 and MeWo cells to the COX-2 selective inhibitor, NS398 (10μM). NS398 (10μM) selectively sensitized hypoxic HeLa and MCF-7 but not MeWo cells to ionising radiation (5 Gy). Furthermore, while knockdown of COX-2 with siRNA did not affect either normoxic radiosensitivity in HeLa cells, the radiosensitisation observed with NS398 was lost suggesting both COX-2 dependent and independent mechanisms. We also show that ionising radiation at 5 Gy results in phosphorylation of p53 at serine 15, a key phosphorylation site for p53-mediated apoptosis, and that hypoxia attenuates this phosphorylation. Attenuated phosphorylation of p53 under hypoxic conditions may therefore contribute to hypoxic radioresistance. We also show that NS398 selectively phosphorylates p53 under hypoxic conditions following irradiation at 5 Gy. p53 phosphorylation could be an underlying mechanism by which this agent and other COX-2 inhibitors sensitize tumors to radiation therapy.

PARylation of GCN5 by PARP1 mediates its recruitment to DSBs and facilitates both HR and NHEJ Repair

Efficient DNA double strand break (DSB) repair is necessary for genomic stability and determines efficacy of DNA damaging cancer therapeutics. Spatiotemporal dynamics and post-translational modifications of repair proteins at DSBs dictate repair efficacy. Here, we identified a non-canonical function of GCN5 in regulating both HR and NHEJ repair post genotoxic stress. Mechanistically, genotoxic stress induced GCN5 recruitment to DSBs. GCN5 PARylation by PARP1 was essential for its recruitment, acetyltransferase activity and DSB repair function. Liquid chromatography-mass spectrometry (LC-MS) identified DNA-PKcs as part of GCN5 interactome. In-vitro acetyltransferase assays revealed that GCN5 acetylates DNA-PKcs at K3241 residue, a prerequisite for DNA-PKcs S2056 phosphorylation and DSB recruitment. Alongside, ChIP-qPCR revealed GCN5 mediates transcription of PRKDC via H3K27Ac acetylation in its promoter region (- 710 to - 554). Genetic perturbation of GCN5 also decreased CHEK1, NBN1, TP53BP1, POL-L transcription and abrogated ATM, BRCA1 activation. Accordingly, GCN5 loss led to persistent ɣ-H2AX foci formation, compromised in-vivo HR-NHEJ and caused GBM radio-sensitization. Importantly, PARP1 inhibition phenocopied GCN5 loss. Together, this study identifies an untraversed DSB repair function of GCN5 and provides mechanistic insights into transcriptional as well as post-translational regulation of pivotal HR-NHEJ factors. Alongside, it highlights the translational importance of PARP1-GCN5 axis in mediating GBM radio-resistance.