Radiosensitivity Of Cancer Cells Research Articles

USP9X-mediated REV1 deubiquitination promotes lung cancer radioresistance via the action of REV1 as a Rad18 molecular scaffold for cystathionine γ-lyase.

Radioresistance is a key clinical constraint on the efficacy of radiotherapy in lung cancer patients. REV1 DNA directed polymerase (REV1) plays an important role in repairing DNA damage and maintaining genomic stability. However, its role in the resistance to radiotherapy in lung cancer is not clear. This study aims to clarify the role of REV1 in lung cancer radioresistance, identify the intrinsic mechanisms involved, and provide a theoretical basis for the clinical translation of this new target for lung cancer treatment. The effect of targeting REV1 on the radiosensitivity was verified by in vivo and in vitro experiments. RNA sequencing (RNA-seq) combined with nontargeted metabolomics analysis was used to explore the downstream targets of REV1. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify the content of specific amino acids. The coimmunoprecipitation (co-IP) and GST pull-down assays were used to validate the interaction between proteins. A ubiquitination library screening system was constructed to investigate the regulatory proteins upstream of REV1. Targeting REV1 could enhance the radiosensitivity in vivo, while this effect was not obvious in vitro. RNA sequencing combined with nontargeted metabolomics revealed that the difference result was related to metabolism, and that the expression of glycine, serine, and threonine (Gly/Ser/Thr) metabolism signaling pathways was downregulated following REV1 knockdown. LC-MS/MS demonstrated that REV1 knockdown results in reduced levels of these three amino acids and that cystathionine γ-lyase (CTH) was the key to its function. REV1 enhances the interaction of CTH with the E3 ubiquitin ligase Rad18 and promotes ubiquitination degradation of CTH by Rad18. Screening of the ubiquitination compound library revealed that the ubiquitin-specific peptidase 9 X-linked (USP9X) is the upstream regulatory protein of REV1 by the ubiquitin-proteasome system, which remodels the intracellular Gly/Ser/Thr metabolism. USP9X mediates the deubiquitination of REV1, and aberrantly expressed REV1 acts as a scaffolding protein to assist Rad18 in interacting with CTH, promoting the ubiquitination and degradation of CTH and inducing remodeling of the Gly/Ser/Thr metabolism, which leads to radioresistance. A novel inhibitor of REV1, JH-RE-06, was shown to enhance lung cancer cell radiosensitivity, with good prospects for clinical translation.

Growth hormone-releasing hormone (GHRH) antagonists enhance radiosensitivity in non-small cell lung cancer cells

Growth hormone-releasing hormone (GHRH) antagonists enhance radiosensitivity in non-small cell lung cancer cells

Mechanism of Musashi2 affecting radiosensitivity of lung cancer by modulating DNA damage repair.

Identifying new targets for overcoming radioresistance is crucial for improving the efficacy of lung cancer radiotherapy, given that tumor cell resistance is a leading cause of treatment failure. Recent research has spotlighted the significance of Musashi2 (MSI2) in cancer biology. In this study, we first demonstrated that MSI2 plays a key function in regulating the radiosensitivity of lung cancer. The expression of MSI2 is negatively correlated with overall survival in cancer patients, and the knockdown of MSI2 inhibits tumorigenesis and increases radiosensitivity of lung cancer cells. Cellular radiosensitivity, which is closely linked to DNA damage, is influenced by MSI2 interaction with ataxia telangiectasia mutated and Rad3-related kinase (ATR) and checkpoint kinase 1 (CHK1) post-irradiation; moreover, knockdown of MSI2 inhibits the ATR-mediated DNA damage response pathway. RNA-binding motif protein 17 (RBM17), which is implicated in DNA damage repair, exhibits increased interaction with MSI2 post-irradiation. We found that knockdown of RBM17 disrupted the interaction between MSI2 and ATR post-irradiation and increased the radiosensitivity of lung cancer cells. Furthermore, we revealed the potential mechanism of MSI2 recruitment into the nucleus with the assistance of RBM17 to activate ATR to promote radioresistance. This study provides novel insights into the potential application of MSI2 as a new target in lung cancer radiotherapy.

Effects of p300 inhibition on prostate cancer cell growth

Background: Radiation is a central component of many anti-cancer therapy regimens, utilized for more than half of all cancer patients. Despite advances in the delivery and success of radiation treatment, many individuals express, or will develop, radioresistance, a major contributor to treatment failure and malignant progression. While the etiology of radioresistance is complex, it may be mediated in part by expression of p300, a histone acetyltransferase known to facilitate DNA repair. We hypothesized that inhibition of p300 would increase radiosensitivity of prostate cancer cells in vitro. Methods: Human prostate adenocarcinoma (PC-3) cells were grown in tissue culture flasks incubated at 37° C with 5% CO2. Cells were randomized to receive 1 μM CCS 1477, a selective inhibitor of p300, or vehicle for 1 hour prior to a single treatment of 0 Gy (NR+ or NR-, respectively) or 2 Gy radiation (R+ or R-, respectively). Four hours after radiation, cells were seeded into 100 mm diameter tissue culture dishes and incubated for 10 days. Cells were then stained, and colonies > 50 cells were counted to determine clonogenic survival. Cell survival was corrected for plating effciency and group comparisons were made using a two-way ANOVA. Results: Results were determined from the average of 3 separate experiments. Compared to non-radiated controls (NR-), survival of R- was reduced to 47%, while survival of R+ was reduced to 32%. However, there was no significant difference between % survival of R- and R+. Conclusions: In vitro, 1 μM exposure to CCS 1477 does not reduce clonogenic survival in PC-3 cells subjected to 2 Gy radiation. The duration of exposure and concentration of CCS 1477 may not be adequate to elicit significant improvements in radiosensitivity of PC-3 cells to 2 Gy radiation. Future experiments will explore the effects of varying durations of exposure and concentrations of CCS 1477. Additionally, it remains to be determined whether CCS 1477 improves radiosensitivity in other cancer cell lines (e.g., breast cancer). Johnson Cancer Research Center. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Role of Non-coding RNAs on the Radiotherapy Sensitivity and Resistance in Cancer Cells.

Radiotherapy (RT) is an integral part of treatment management in cancer patients. However, one of the limitations of this treatment method is the resistance of cancer cells to radiotherapy. These restrictions necessitate the introduction of modalities for the radiosensitization of cancer cells. It has been shown that Noncoding RNAs (ncRNAs), along with modifiers, can act as radiosensitivity and radioresistant regulators in a variety of cancers by affecting double strand break (DSB), wnt signaling, glycolysis, irradiation induced apoptosis, ferroptosis and cell autophagy. This review will provide an overview of the latest research on the roles and regulatory mechanisms of ncRNA after RT in in vitro and preclinical research.

AM-18002, a derivative of natural anmindenol A, enhances radiosensitivity in mouse breast cancer cells.

Natural anmindenol A isolated from the marine-derived bacteria Streptomyces sp. caused potent inhibition of inducible nitric oxide synthase without any significant cytotoxicity. This compound consists of a structurally unique 3,10-dialkylbenzofulvene skeleton. We previously synthesized and screened the novel derivatives of anmindenol A and identified AM-18002, an anmindenol A derivative, as a promising anticancer agent. The combination of AM-18002 and ionizing radiation (IR) improved anticancer effects, which were exerted by promoting apoptosis and inhibiting the proliferation of FM3A mouse breast cancer cells. AM-18002 increased the production of reactive oxygen species (ROS) and was more effective in inducing DNA damage. AM-18002 treatment was found to inhibit the expansion of myeloid-derived suppressor cells (MDSC), cancer cell migration and invasion, and STAT3 phosphorylation. The AM-18002 and IR combination synergistically induced cancer cell death, and AM-18002 acted as a potent anticancer agent by increasing ROS generation and blocking MDSC-mediated STAT3 activation in breast cancer cells.

Abstract LB015: Differential expression of deubiquitinating enzymes and its related DNA damage response genes in neuroblastoma heterogeneity

Abstract SK-N-AS and SK-N-DZ are two cell lines of pediatric solid tumors neuroblastomas well characterized to evaluate heterogeneity between different neuroblastomas and are presumed as models for differences between different neuroblastoma. Using this model system, we recently evaluated if radiation could improve efficacy of radiation therapy and to follow these studies later with animal models to determine decrease of tumor burden. Differences between the N-type and S-type neuroblastoma cell lines SK-N-DZ and SK-N-AS, respectively were observed to be high and their responses to radiation stress were equally heterogeneous. Ubiquitin signaling plays a key role during the DNA damage response in protein recruitment and protein interactions. Deubiquitinating enzymes (DUBs) deconjugate ubiquitin from ubiquitylated substrate proteins to control their activity and stability and are shown to regulate various biological processes. DUBs may play a role in regulating the radiosensitivity of cancer cells by modulating DNA damage response and repair pathways. Determination of specific DUBs that are involved in regulating radiosensitivity in cancer cells will provide opportunity for drug targeting and visa-vis enhance the efficacy of radiation therapy in neuroblastoma cancer treatment. Here, using bioinformatic tools, the differentially regulated DUBs were identified. The relationship between DEGs-DUBs with the genes involved in various DNA repair pathways (NHEJ, HR and Fanconi anemia pathway; KEGG pathway database) are described. We identified 32 DEGs (14 upregulated and 18 downregulated) with these neuroblastoma cell lines. USP22 and USP41 DUBs and its differential expression in these cell lines denotes the importance of such analysis. Especially considering USP22 a potentially biomarker for predicting the outcome of patients with neuroblastoma. These DEG-DUBs were likewise correlated with 91 DNA damage response (DDR) genes belonging to three different pathways (NHEJ, HR and Fanconi anemia pathway). Out of which 44 of the DDR genes showed significant correlation with DEG-DUBs. Further studies are needed to determine the mechanisms underlying the complex relationship of these DUBs and to determine the critical DUBs for drug targeting and to enhance the efficacy of radiation therapy in cancer treatment. Citation Format: Vaibhav Vaibhav, Fahika Nazeerulla, Tatjana Paunesku, Ekta Tripathi, Gayle Woloschak, Prashanthi Karyala, Rao V. Papineni. Differential expression of deubiquitinating enzymes and its related DNA damage response genes in neuroblastoma heterogeneity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB015.

Abstract 688: Radium-223 in combination with darolutamide exhibits synergistic antitumor efficacy in LNCaP prostate cancer models

Abstract Radium-223 dichloride (radium-223) is a targeted alpha therapy that binds to newly formed abnormal bone in bone metastases and induces DNA double-strand breaks (DSBs) in cancer cells, osteoblasts and osteoclasts. Radium-223 is used for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC). Darolutamide is an androgen receptor inhibitor indicated for patients with metastatic hormone-sensitive prostate cancer or non-metastatic CRPC. We studied the antitumor effects of radium-223 in combination with darolutamide using LNCaP human prostate cancer cells in vitro and an intratibial LNCaP model mimicking prostate cancer metastasized to bone. The in vitro antiproliferative effects of radium-223 and darolutamide were determined using LNCaP cells. Gene set enrichment analysis (GSEA) was conducted on RNA sequencing data from LNCaP cells treated with the synthetic androgen R1881 alone or in combination with darolutamide. LNCaP cells were inoculated into the right tibia of male NOD.scid mice. The mice (n=7-9/group) were randomized based on serum prostate-specific antigen (PSA) and treated with vehicle, radium-223 (330 kBq/kg, Q4Wx2, i.v.), darolutamide (100 mg/kg, BID, p.o.), or with a combination of radium-223 and darolutamide, for 41 days. PSA and the bone turnover markers PINP and CTX-I were measured every second week in serum. Tumor-induced abnormal bone area, bone formation rate and radium-223 uptake in tumor-bearing tibiae were determined by X-ray, histomorphometry and gamma counter, respectively. The combination of radium-223 and darolutamide showed synergistic antiproliferative effects with combination indexes between 0.69-0.75 in vitro. GSEA demonstrated a prominent darolutamide-induced downregulation of DNA damage response (DDR) signaling pathways. In vivo, the combination treatment showed synergistic antitumor efficacy (p=0.04) as demonstrated by lower PSA concentrations when compared with the vehicle, radium-223 or darolutamide monotherapies (p=0.004, p=0.011 and p=0.002, respectively). In the vehicle and combination treatment groups, the mean serum PSA was 541% and 95.9% of the pre-treatment level, respectively. Furthermore, radium-223 alone or in combination with darolutamide inhibited increased bone turnover, tumor-induced abnormal bone growth and trabecular bone formation when compared to vehicle. Concurrent administration of darolutamide did not affect radium-223 uptake in tibiae. Radium-223 in combination with darolutamide exhibited synergistic antitumor efficacy both in vitro and in vivo. The synergistic effects could be due to the radiosensitization of cancer cells by darolutamide-induced downregulation of DDR pathways. Our results suggest that the combination of targeted alpha therapy with an androgen receptor inhibitor is a promising treatment strategy for mCRPC. Citation Format: Christoph A. Schatz, Mari I. Suominen, Andreas Schlicker, Matias Knuuttila, Esa Alhoniemi, Sanna-Maria Käkönen, Bernard Haendler, Urs B. Hagemann, Arne Scholz. Radium-223 in combination with darolutamide exhibits synergistic antitumor efficacy in LNCaP prostate cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 688.

Abstract 694: Evaluation of a synergistic drug combination with 177Lu-rhPSMA-10.1 for prostate cancer: Results of an in vitro screen and in vivo proof of concept study

Abstract Purpose: Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) has been shown to extend survival in men with advanced prostate cancer (PCa). Novel radiohybrid (rh) PSMA-targeted 177Lu-rhPSMA-10.1 has shown promising preclinical efficacy and advantageous radiation dosimetry in humans. We conducted an in vitro screen to identify known anticancer drugs with potential for synergistic interaction with 177Lu-rhPSMA-10.1. Here we present key screening data and a subsequent in vivo efficacy analysis of the lead novel drug combination in PSMA-expressing 22Rv1 PCa xenografts. Methods: Over 150 FDA-approved anticancer drugs were screened in a clonogenic survival assay of 22Rv1 cells using the test drug alone, at a range of concentrations <20 µM to determine the IC50, and results compared to incubations of the drug + 15 MBq/mL 177Lu-rhPSMA-10.1 after 10 d. A focused screen of 5 lead candidates was then conducted to determine the impact of 177Lu-rhPSMA-10.1 (0-25 MBq/mL) on the drug IC50. A synergy score was determined using the zero interaction potency (ZIP) reference model and the multi-dimensional synergy of combinations (MuSyc) platform. Subsequently, to evaluate the efficacy of the lead combination, 177Lu-rhPSMA-10.1 (single 30 MBq iv dose) and Cobimetinib (0.25 mg orally per day for 21 d) alone and in combination were administered to 22Rv1 tumor-bearing NMRI nude mice (n = 8 per group plus untreated controls). Tumor volume was measured 2x week for 69 d. Two-way ANOVA and Tukey’s multiple comparisons test (data analyzed until n = 3 remained per group) and Kaplan-Meier Log-rank survival analyses were performed. Results: The in vitro screen identified MEK inhibitor Cobimetinib as a lead candidate for synergistic combination with 177Lu-rhPSMA-10.1 across a wide concentration range, with a ZIP synergy score of 13.25% (95% CI ± 2.17) and promising results on MuSyc analysis. The 177Lu-rhPSMA-10.1 + Cobimetinib combination significantly suppressed tumor growth in vivo vs untreated controls (from day 13-30; p<0.01) and 177Lu-rhPSMA-10.1 alone (from day 17-30; p<0.001). The median survival in the combination group (49 d) was significantly longer vs the untreated group (23 d; p=0.001) and the group treated with 177Lu-rhPSMA-10.1 alone (36 d; p=0.002). Conclusions: Through an extensive in vitro screen, we identified Cobimetinib to have potential for a synergistic anti-tumor effect in combination with 177Lu-rhPSMA-10.1. This may be due to inhibition of the MEK-MAPK pathway by Cobimetinib during DNA damage response, resulting in radiosensitization of cancer cells to 177Lu-labeled RLT agents such as 177Lu-rhPSMA-10.1. This novel combination showed an enhanced therapeutic efficacy vs the single agents in 22Rv1 xenografts and the lack of overlapping monotherapy toxicity reported in the clinic supports clinical investigation in men with PCa. Citation Format: Caroline Foxton, Bart Cornelissen, Edward O'Neill, Bradley Waldron, Freja Pretzmann, Rikke Veggerby Grønlund, Mathias Wikke Hallund, Daniel J. Stevens. Evaluation of a synergistic drug combination with 177Lu-rhPSMA-10.1 for prostate cancer: Results of an in vitro screen and in vivo proof of concept study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 694.

Clobetasol propionate, a Nrf-2 inhibitor, sensitizes human lung cancer cells to radiation-induced killing via mitochondrial ROS-dependent ferroptosis.

Combining radiotherapy with Nrf-2 inhibitor holds promise as a potential therapeutic strategy for radioresistant lung cancer. Here, the radiosensitizing efficacy of a synthetic glucocorticoid clobetasol propionate (CP) in A549 human lung cancer cellswas evaluated. CP exhibited potent radiosensitization in lung cancer cells via inhibition of Nrf-2 pathway, leading to elevation of oxidative stress. Transcriptomic studies revealed significant modulation of pathways related to ferroptosis, fatty acid and glutathione metabolism. Consistent with these findings, CP treatment followed by radiation exposure showed characteristic features of ferroptosis in terms of mitochondrial swelling, rupture and loss of cristae. Ferroptosis is a form of regulated cell death triggered by iron-dependent ROS accumulation and lipid peroxidation. In combination with radiation, CP showed enhanced iron release, mitochondrial ROS, and lipid peroxidation, indicating ferroptosis induction. Further, iron chelation, inhibition of lipid peroxidation or scavenging mitochondrial ROS prevented CP-mediated radiosensitization. Nrf-2 negatively regulates ferroptosis through upregulation of antioxidant defense and iron homeostasis. Interestingly, Nrf-2 overexpressing A549 cells were refractory to CP-mediated ferroptosis induction and radiosensitization. Thus, this study identifiedanti-psoriatic drug clobetasol propionate can be repurposed as a promising radiosensitizer for Keap-1 mutant lung cancers.

Nicaraven attenuates the acquired radioresistance of established tumors in mouse models via PARP inhibition.

Nicaraven has been reported to inhibit the activity of poly (ADP-ribose) polymerase (PARP). In this study, we investigated the probable ability of nicaraven to attenuate cancer radioresistance during fractionated radiotherapy. Tumor models were established in C57BL/6 mice and BALB/c nude mice by subcutaneous injection of Lewis mouse lung carcinoma cancer cells and A549 human lung cancer cells, respectively. When the tumors had grown to approximately 100 mm3, we initiated fractionated radiotherapy. Nicaraven or saline was administered immediately after each irradiation exposure. Compared to saline treatment, nicaraven administration significantly induced gamma-H2AX foci formation and cell apoptosis in tumors at 1 or 3days after an additional challenge exposure to 10Gy and inhibited tumor growth during the short-term follow-up period, suggesting increased radiosensitivity of cancer cells. Moreover, the expression of PARP in tumor tissue was decreased by nicaraven administration. Our data suggest that nicaraven likely attenuates the acquired radioresistance of cancers through PARP inhibition.

Targeting FBXO22 enhances radiosensitivity in non-small cell lung cancer by inhibiting the FOXM1/Rad51 axis

Radioresistance is a major constraint on the efficacy of lung cancer radiotherapy, but its mechanism has not been fully elucidated. Here, we found that FBXO22 was aberrantly highly expressed in lung cancer and that FBXO22 knockdown increased the radiosensitivity of lung cancer cells. Mechanistically, FBXO22 promoted Rad51 gene transcription by increasing the level of FOXM1 at the Rad51 promoter, thereby inducing the formation of lung cancer radioresistance. Furthermore, we found that deguelin, a potential inhibitor of FBXO22, enhanced radiosensitivity in an FBXO22/Rad51-dependent manner and was safely tolerated in vivo. Collectively, our results illustrate that FBXO22 induces lung cancer radioresistance by activating the FOXM1/Rad51 axis and provide preclinical evidence for the clinical translation of this critical target.

LKB1 Mutations Enhance Radiosensitivity in Non-Small Cell Lung Cancer Cells by Inducing G2/M Cell Cycle Phase Arrest.

Radiosensitivity remains an important factor affecting the clinical outcome of radiotherapy for non-small cell lung cancer (NSCLC). Liver kinase B1 (LKB1) as a tumor suppressor, is one of the most commonly mutated genes in NSCLC. However, the role of LKB1 on radiosensitivity and the possible mechanism have not been elucidated in the NSCLC. In this study, we investigated the regulatory function of LKB1 in the radiosensitivity of NSCLC cells and its possible signaling pathways. After regulating the expression of LKB1, cell proliferation was determined by Cell Counting Kit-8 (CCK-8) assay. The flow cytometry assay was used to analyse cell cycle distribution. Survival fraction and sensitization enhancement ratio (SER) were generated by clonogenic survival assay. Western blot analysis was used to assess expression levels of LKB1, p53, p21, γ-H2AX and p-Chk2. Our study found that when the NSCLC cells were exposed to ionizing radiation, LKB1 could inhibit NSCLC cell proliferation by promoting DNA double strand break and inducing DNA repair. In addition, LKB1 could induce NSCLC cells G1 and G2/M phase arrest through up-regulating expression of p53 and p21 proteins. This current study demonstrates that LKB1 enhances the radiosensitivity of NSCLC cells via inhibiting NSCLC cell proliferation and inducing G2/M phase arrest, and the mechanism of cell cycle arrest associated with signaling pathways of p53 and p21 probably.

Effect of Functional Inhibition of BACE1 on Sensitization to γ-Irradiation in Cancer Cells.

Developing strategies for the radiosensitization of cancer cells by the inhibition of genes, which harbor low toxicity to normal cells, will be useful for improving cancer radiotherapy. Here, we focused on a β-site of amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1; β-secretase, memapsin-2). By functional inhibition of this peptidase by siRNA, it has also recently been shown that the DNA strand break marker, γH2AX foci, increased, suggesting its involvement in DNA damage response. To investigate this possibility, we knocked down BACE1 with siRNA in cancer cell lines, and sensitization to γ-irradiation was examined by a colony formation assay, γH2AX foci and level analysis, and flow cytometry. BACE1 knockdown resulted in the sensitization of HeLa, MDA-MB-231, U2OS, and SAOS cells to γ-irradiation in a diverse range. BACE1 knockdown showed a weak radiosensitization effect in osteosarcoma U2OS cells, which has a normal p53 function. HeLa and SAOS cells, which harbor p53 dysfunction, exhibited a greater level of radiosensitization. These results suggest that BACE1 may be a potential target for the radiosensitization in particular cancer cells.

Aldolase A promotes cervical cancer cell radioresistance by regulating the glycolysis and DNA damage after irradiation

ABSTRACT Radioresistance is the major obstacle that affects the efficacy of radiotherapy which is an important treatment for cervical cancer. By analyzing the databases, we found that aldolase A (ALDOA), which is a key enzyme in metabolic reprogramming, has a higher expression in cervical cancer patients and is associated with poor prognosis. We detected the expression of ALDOA in the constructed cervical cancer radioresistance (RR) cells by repetitive irradiation and found that it was upregulated compared to the control cells. Functional assays were conducted and the results showed that the knockdown of ALDOA in cervical cancer RR cells inhibited the proliferation, migration, and clonogenic abilities by regulating the cell glycolysis. In addition, downregulation of ALDOA enhanced radiation-induced apoptosis and DNA damage by causing G2/M phase arrest and further promoted radiosensitivity of cervical cancer cells. The functions of ALDOA in regulating tumor radiosensitivity were also verified by the mouse tumor transplantation model in vivo. Therefore, our study provides new insights into the functions of ALDOA in regulating the efficacy of radiotherapy and indicates that ALDOA might be a promising target for enhancing radiosensitivity in treating cervical cancer patients.

Nanodiamond Effects on Cancer Cell Radiosensitivity: The Interplay between Their Chemical/Physical Characteristics and the Irradiation Energy

Nanoparticles are being increasingly studied to enhance radiation effects. Among them, nanodiamonds (NDs) are taken into great consideration due to their low toxicity, inertness, chemical stability, and the possibility of surface functionalization. The objective of this study is to explore the influence of the chemical/physical properties of NDs on cellular radiosensitivity to combined treatments with radiation beams of different energies. DAOY, a human radioresistant medulloblastoma cell line was treated with NDs—differing for surface modifications [hydrogenated (H-NDs) and oxidized (OX-NDs)], size, and concentration—and analysed for (i) ND internalization and intracellular localization, (ii) clonogenic survival after combined treatment with different radiation beam energies and (iii) DNA damage and apoptosis, to explore the nature of ND–radiation biological interactions. Results show that chemical/physical characteristics of NDs are crucial in determining cell toxicity, with hydrogenated NDs (H-NDs) decreasing either cellular viability when administered alone, or cell survival when combined with radiation, depending on ND size and concentration, while OX-NDs do not. Also, irradiation at high energy (γ-rays at 1.25 MeV), in combination with H-NDs, is more efficient in eliciting radiosensitisation when compared to irradiation at lower energy (X-rays at 250 kVp). Finally, the molecular mechanisms of ND radiosensitisation was addressed, demonstrating that cell killing is mediated by the induction of Caspase-3-dependent apoptosis that is independent to DNA damage. Identifying the optimal combination of ND characteristics and radiation energy has the potential to offer a promising therapeutic strategy for tackling radioresistant cancers using H-NDs in conjunction with high-energy radiation.

Synthesis of CuS nanoparticles for enhance radiosensitization of cancer cells

Researchers have become more interested in new nanotechnologies for radiotherapy over the past few years. To increase radiotherapy (RT) efficacy, it is very desirable to design nanoparticles (NPs) that efficiently generate hazardous reactive oxygen species (ROS) when exposed to X-rays. As a potential nanoradiosensitizer, the potential of CuS NPs, is investigated here. For this aim, bovine serum albumin (BSA) coated CuS NPs, CuS@BSANPs, were synthesized through a biomineralization approach. CuS@BSANPs show a spherical shape and have an average size of 13.15 ± 3.4 nm. It show hydrodynamic size about 37 nm and the zata potential about −45 mV. MTT assay shows that 4T1 cells growth was inhibited when it was co-treated with CuS@BSANPs and X-ray irradiation. Under combination therapy, there is a large rise in the ROS level in the cells, which plays an important role in the greater damage caused to cancer cells. The CuS@BSANPs show the potential to be a very effective nanoradiosensitizer agent for the treatment of cancer.

LTBK-09. RESULTS OF BMX-HGG STUDY: A MULTI-INSTITUTIONAL, RANDOMIZED PHASE 2 CLINICAL TRIAL OF CONCURRENT CHEMORADIATION WITH OR WITHOUT BMX-001 IN PATIENTS WITH NEWLY DIAGNOSED HIGH GRADE GLIOMA

Abstract BACKGROUND Standard treatment for high grade glioma (HGG) remains neurosurgical resection followed by concurrent radiation therapy (RT) and temozolomide (TMZ). Overall survival (OS) for GBM is roughly 12-16 months. RT is associated with cognitive and quality of life (QoL) impairments. Advances are needed to improve OS while mitigating injury to the normal brain. BMX-001 is a novel metalloporphyrin that radiosensitizes cancer cells and radioprotects normal tissue. METHODS This multi-institutional, open-label, phase 2 trial randomized newly diagnosed HGG patients to receive RT/TMZ with or without BMX-001 (NCT02655601). Both arms received 6 weeks RT/TMZ (75 mg/m2). BMX-001 was administered as a loading dose of 28 mg sc before RT, followed by 14 mg twice weekly for 8 weeks. Randomization was stratified by tumor grade and institution. Key eligibility criteria include histologically confirmed HGG, age ≥ 18 years, and KPS ≥ 70%. The primary endpoint was OS. Key secondary/exploratory outcomes included cognition, QoL, and white matter integrity using advanced imaging. OS evaluation occurred after 84 deaths when a 1-tailed logrank test (α=0.2) had 90% power to detect a hazard ratio of 0.63. Two interim analyses and a final analysis were conducted using an O’Brien-Fleming stopping boundary. RESULTS Of the 160 patients randomized, 72.5% had GBM, and 62.5% were male. Analyses focused on 145 patients who completed RT/TMZ (74 with BMX-001, 71 without BMX-001). Median OS of BMX-001+RT/TMZ group (31.3 [95% CI, 21.6, not reached] months) was longer than RT/TMZ group (24.7 [95% CI, 19.6-32.6] months), HR=0.735; p=0.079 (significant at the predefined α level). Common toxicities (Grade 1-2) attributed to BMX-001 were injection site reactions (64), tachycardia (24), and pruritus (17) with no related Grade 4-5. Diffusion tensor MR imaging indicated mitigation of dose-related white matter damage in BMX-001+RT/TMZ group. CONCLUSIONS BMX-001 is safe, and there is improved OS in HGG patients receiving BMX-001.

Effect of gold nanocomposite bearing HIF-1α siRNA on radiotherapy in nasopharyngeal carcinoma cell

Purpose: To investigate the effect of gold nanocomposite carrying hypoxia-inducible factor-1α (HIF-1α) siRNA on radiosensitivity of nasopharynx cancer (NPC) cells.
 Methods: Gold nanocomposite (AuNRs-(PEI-PEG)/RGD) or (AuPPR) was first synthesized and its cytotoxicity was evaluated. Then, the expression of HIF-1α in hypoxic NPC cells was assessed. In addition, the radiation sensitivity of AuPPR bearing HIF-1α siRNA on the cells was examined under xray exposure.
 Result: Gold nanocomposite (AuPPR) carrying HIF-1α siRNA (AuPPR-HIF-1α siRNA) significantly down-regulated HIF-1α expression. Under irradiation treatment, AuPPR-HIF-1α siRNA significantly enhanced apoptosis of NPC cells by 33.76 ± 3.65 %, when compared to the control and simple AuPPR group (22.5 ± 4.16 %, p < 0.01). Furthermore, cell cycle was significantly blocked in the sub-G1 phase in AuPPR-HIF-1α siRNA radiotherapy groups, indicating severe cell damage.
 Conclusion: This study has demonstrated that AuPPR-HIF-1α siRNA is effective in improving the radiosensitivity of nasopharyngeal carcinoma cells under hypoxia, and therefore can potentially be used to improve the radiotherapy of this carcinoma

The COX-2/PGE2 Response Pathway Upregulates Radioresistance in A549 Human Lung Cancer Cells through Radiation-Induced Bystander Signaling.

This study aimed to determine the mechanism underlying the modulation of radiosensitivity in cancer cells by the radiation-induced bystander effect (RIBE). We hypothesized that the RIBE mediates cyclooxygenase-2 (COX-2) and its metabolite prostaglandin E2 (PGE2) in elevating radioresistance in unirradiated cells. In this study, we used the SPICE-QST microbeam irradiation system to target 0.07-0.7% cells by 3.4-MeV proton microbeam in the cell culture sample, such that most cells in the dish became bystander cells. Twenty-four hours after irradiation, we observed COX-2 protein upregulation in microbeam-irradiated cells compared to that of controls. Additionally, 0.29% of the microbeam-irradiated cells exhibited increased cell survival and a reduced micronucleus rate against X-ray irradiation compared to that of non-microbeam irradiated cells. The radioresistance response was diminished in both cell groups with the hemichannel inhibitor and in COX-2-knockout cells under cell-to-cell contact and sparsely distributed conditions. The results indicate that the RIBE upregulates the cell radioresistance through COX-2/PGE2 intercellular responses, thereby contributing to issues, such as the risk of cancer recurrence.