Sodium glycididazole enhances the radiosensitivity of laryngeal cancer cells through downregulation of ATM signaling pathway

Enhanced radiotherapy using photothermal therapy based on dual-sensitizer of gold nanoparticles with acid-induced aggregation

The damaged DNA strands caused by radiotherapy (RT) can repair by themselves. A gold nanoparticles (GNPs) system with acid-induced aggregation was developed into a dual sensitizer owing to its high radioactive rays attenuation ability and enhanced photothermal heating efficiency after GNPs aggregation to achieve a combination therapy of RT and photothermal therapy (PTT). In this combination therapy, the formed GNP aggregates firstly showed a higher sensitize enhancement ratio (SER) value (1.52). Importantly, the self-repair of damaged DNA strands was inhibited by mild PTT through down-regulating the expression of DNA repair protein, thus resulting in a much higher SER value (1.68). Anti-tumor studies further demonstrated that this combination therapy exhibited ideal anti-tumor efficacy. Furthermore, the imaging signals of GNPs in computed tomography and photoacoustic were significantly improved following the GNPs aggregation. Therefore, a dual sensitizer with multimodal imaging was successfully developed and can be further applied as a new anti-tumor therapy.

High pATM is Associated With Poor Local Control in Supraglottic Cancer Treated With Radiotherapy

Objectives

Most early stage laryngeal squamous cell carcinomas (LSCC) are treated with radiotherapy. Discovery of new biomarkers are needed to improve prediction of outcome after radiotherapy and to identify potential targets for systemic targeted therapy. The ataxia telangiectasia mutated (ATM) gene plays a critical role in DNA damage response induced by ionizing radiation.

Methods

The prognostic value of immunohistochemical expression of pATM, pChk2, and p53 were investigated in 141 patients with T1‐T2 LSCC curatively treated with external beam radiotherapy. Uni‐ and multivariable Cox regression analyses were performed to examine the relation between expression levels of markers and local control.

Results

Local control was significantly worse in cases with high levels of pATM (HR 2.14; 95% CI, 1.08–4.24; P = .03). No significant associations with local control were found for pChk2 and p53 expression. The association of high pATM expression with poor local control was only found for supraglottic LSCC (HR 10.9; 95% CI, 1.40–84.4; P = .02).

Conclusion

Our findings suggest a potential role for ATM in response to radiotherapy in early stage supraglottic LSCC and imply ATM inhibition as a possibility to improve response to radiotherapy.

Level of Evidence

NA Laryngoscope, 130: 1954–1960, 2020

The Radiosensitization of Sodium Glycididazole on Nasopharyngeal Carcinoma Cells via Enhancing DNA Damage and Promoting Apoptosis

Background: The radioresistance of nasopharyngeal carcinoma (NPC) was the main cause of radiotherapy failure and it was still a challenge in the treatment of advanced NPC patients. Previous clinical studies demonstrated that sodium glycididazole(CMNA) can enhance the radiosensitivity of NPC, but the corresponding cellular mechanisms or processes remains largely unclear. Methods: To clarify the radiosensitizing effects of CMNA on NPC cells and reveal its cellular mechanisms, its effect on cell survival of NPC cells was assessed by MTT and clonogenic assay, with or without radiation. The potential cellular mechanisms such as cell cycle distribution, apoptosis and DNA damage were assessed. A retrospective analysis of the outcome of patients with III-IV stage NPC who undergo same radiochemotherapy with or without concurrent CMNA treatment was performed to elucidate the role of CMNA in the improvement of the curative effects. Results: The treatment with CMNA at the concentration lower or close to the clinical dosage had little effect on cell survival, cell cycle distribution and a weak effect on DNA damage and cell apoptosis of NPC cells. The combination of CMNA and radiation significantly increased the DNA damage and enhanced the apoptosis of NPC cells, but did not significantly alter the cell cycle distribution as compared with the irradiation (IR) alone. A total of 99 patients who underwent radiochemotherapy were categorized into those with (treatment group, n=52) and without (control group, n=47) the treatment with CMNA. The complete response rates of patients in treatment group were significantly higher than in control group. Conclusions: Our results suggested that CMNA enhance the sensitivity of the NPC cells to radiation via enhancing DNA damage and promoting cell apoptosis. It provides clues for further investigation of the molecular mechanism of the radiosensitization of CMNA on NPC cells.

Hypoxia-responsive block copolymer radiosensitizers as anticancer drug nanocarriers for enhanced chemoradiotherapy of bulky solid tumors

Radiosensitizers play an important role in the clinical radiotherapy of hypoxic solid tumors to improve therapeutic efficacy. However, the in vivo performance of clinically used small-molecule radiosensitizers is commonly compromised by low bioavailability in hypoxic tumor regions. Herein, amphiphilic block copolymer radiosensitizers are prepared from clinically approved poly(ethylene glycol)-block-poly(l-glutamic acid) (PEG-b-PLG) and metronidazole (MN) to obtain MN-grafted PEG-b-PLG (PEG-b-P(LG-g-MN)) via condensation reaction, which can self-assemble into core-shell micelles as nanoparticle-formulated radiosensitizers in aqueous solution. The radiosensitizers are demonstrated to possess significantly higher sensitization enhancement ratio (SER) of 2.18 and potent in vivo tumor ablation capability upon exposure to electron beam irradiation compared with clinically used sodium glycididazole (GS) with SER of 1.32. Moreover, after optimizing the ratios of carboxyl and MN groups, PEG-b-P(LG-g-MN) micelles can be used to encapsulate doxorubicin (DOX@HMs) efficiently. Hypoxia-responsive structural transformation of MN into hydrophilic aminoimidazole triggers fast DOX release from DOX@HMs. After intravenous injection of DOX@HMs, potent ablation capability against bulky solid tumors (∼500 mm³) is realized at a low radiation dose (4 Gy) via enhanced chemoradiotherapy. Therefore, the developed novel amphiphilic block copolymer radiosensitizers can be concurrently used as high-efficiency radiosensitizers and hypoxia-responsive DOX nanocarriers for enhanced chemoradiotherapy.

Preclinical study on hypoxic radiosensitizing effects of glycididazole in comparison with those of doranidazole in vitro and in vivo

To overcome the radioresistance of hypoxic cells in solid tumor, numerous types of radiosensitizers specifically against them have been developed. Glycididazole has a chemical structure in which two metronidazole forms are combined, and is widely used as a hypoxic radiosensitizer in China. However, a detailed investigation of its radiosensitizing properties has not been performed. The present study reported a comparative assessment of glycididazole and doranidazole, another hypoxic radiosensitizer. All experiments were performed using the murine squamous cell carcinoma cell line SCCVII. Prior to X-irradiation, the cells were treated with the test drugs at concentrations of 10 mM and 200 mg/kg in vitro and in vivo, respectively. Uptake and their intratumor chemical forms were analyzed by high performance liquid chromatography (HPLC). Both drugs enhanced the reproductive cell death induced by X-irradiation under hypoxia. However, the growth delay assay of the transplanted tumor revealed the combination of X-irradiation and glycididazole showed a similar antitumor effect to that of X-irradiation alone, whereas doranidazole significantly sensitized the cells to X-irradiation. HPLC analysis revealed that incorporated glycididazole was decomposed to metronidazole and was therefore present at a lower concentration compared with that of doranidazole. The decomposition of glycididazole to metronidazole reduced its radiosensitizing efficiency in vivo. Elucidation of the kinetics of drugs containing metabolizable chemical forms is necessary for the optimization of clinical treatment.

Ataxia-Telangiectasia Mutated (ATM) Protein Signaling Participates in Development of Pulmonary Arterial Hypertension in Rats

Background

Previous studies revealed physiological and pathogenetic similarity between vascular smooth muscles cells with severe pulmonary arterial hypertension and tumors. The DNA damage response was found in both pulmonary arterial hypertension (PAH) cells and tumors. The ataxia-telangiectasia mutated proteins (ATM) pathway is considered an important factor in the DNA damage response of tumor formation, but its function in the development of PAH remains unknown.

Material/Methods

The Sprague-Dawley rat PAH model was established. Three weeks (Group M1), 5 weeks (Group M2), and 7 weeks (Group M3) after drug injection, pulmonary expression of ATM, Checkpoint kinase 2 (Chk2), P53, and P21 were measured. A section of the lungs from Group M2 was used for pulmonary artery vascular smooth muscles cells (PA-SMCs) isolation and culture. The effect of KU60019 in the proliferation and apoptosis of primary cultured rat PA-SMCs was measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and TdT-mediated dUTP nick-end labeling (TUNEL), respectively.

Results

Immunohistochemistry results show that the expression of ATM, Chk2, and P21 increased in Groups M1 and M2, and decreased in Group M3. Additionally, expression of P53 increased in Group M1, and decreased in Groups M2 and M3. RT-PCR and Western blotting demonstrated that in Groups M1 and M2, the expression of ATM, Chk2, P53, and P21 increased, whereas it decreased in Group M3. In cell culture, 0.3 μM and 0.5 μM KU60019 increased the growth of PA-SMCs, and 0.5 μM KU60019 reduced cell apoptosis.

Conclusions

Expression of the ATM-Chk2 pathway increased in early stages of PAH formation, but decreased in late stages. In primary cultured PA-SMCs, KU60019 increased cell proliferation and inhibited cell apoptosis.

Enhanced radiosensitizing by sodium glycididazole in a recurrent esophageal carcinoma tumor model

Re-irradiation is challenging for esophageal cancer patients with local-regional recurrence after initial radiotherapy. The purpose of this study is to establish a recurrent esophageal tumor model and investigate radiosensitizing effects of sodium glycididazole (CMNa). Tumor models were established by pre-irradiation (0 Gy, 10 Gy or 20 Gy) to the right hind leg of the nude mice 24 hours before tumor transplantation (ECA109 human esophageal carcinoma cells). Tumor growth curves were analyzed. Hypoxic microenvironment was exhibited in tumor frozen slides stained for pimonidazole, Hoechst 33342, hematoxylin-eosin and CD34. Mice bearing primary (0 Gy pre-irradiation) and recurrent (10 Gy pre-irradiation) tumors were randomized into control (no treatment), radiation (30 Gy in 3 weekly fractionations), or radiation combined with CMNa (1 mmol/kg i.p. injected 60 min before radiation) respectively. The data showed tumors from 10 Gy and 20 Gy pre-irradiated sites grew significantly slower than those in the 0 Gy pre-irradiated group. The recurrent xenograft tumors showed increased necrotic fractions, decreased micro-vascular density, increased pimonidazole-positive fraction, and decreased Hoechst-positive fraction. In the primary xenograft tumors, CMNa adding to radiation did not lead to significant tumor growth delay than radiation alone. However, for the recurrent tumor model, the growth rate was remarkably reduced as CMNa combined with radiation as comparison with radiation alone. In conclusion, the recurrent esophageal xenograft model with tumor bed effect was successfully established characterized by slow growth, increased hypoxia fraction and decreased blood flow. Significant radiosensitization by CMNa was demonstrated in the recurrent model.

Facile Preparation and Radiotherapy Application of an Amphiphilic Block Copolymer Radiosensitizer

Radiosensitizer plays an important role in the cancer radiotherapy for efficient killing of hypoxic cancer cells at a low radiation dose. However, the commercially available small molecular radiosensitizers show low efficiency due to poor bioavailability in tumor tissues. In this report, we develop a novel amphiphilic block copolymer radiosensitizer, metronidazole-conjugated poly(ethylene glycol)-b-poly(γ-propargyl-l-glutamate) (PEG-b-P(PLG-g-MN)), which can be self-assembled into core-shell micelles (MN-Micelle) with an optimal size of ∼60 nm in aqueous solution. In vitro cytotoxicity evaluation indicated that MN-Micelle sensitized the hypoxic cancer cells more efficiently under radiation with the sensitization enhancement ratio (SER) of 1.62 as compared with that of commercially available sodium glycididazole (GS; SER = 1.17) at the metronidazole-equivalent concentration of 180 μg/mL. Upon intravenous injection of MN-Micelle into the tumor-bearing mice, high tumor deposition was achieved, which finally suppressed tumor growth completely after electron beam radiation at a low radiation dose of 4 Gy. MN-Micelle with outstanding performance as an in vivo radiosensitizer holds great potentials for translation into radiotherapy application.

miR-30a radiosensitizes non-small cell lung cancer by targeting ATF1 that is involved in the phosphorylation of ATM

Increasing number of studies report that microRNAs play important roles in radiosensitization. miR-30a has been proved to perform many functions in the development and treatment of cancer, and it is downregulated in non-small cell lung cancer (NSCLC) tissues and cells. This study was conducted to understand if miR-30a plays a role in the radiosensitivity of NSCLC cells. Radiosensitivity was examed by colony survival assay and tumor volume changing in vitro and in vivo, respectively. Bioinformatic analysis and luciferase reporter assays were used to distinguish the candidate target of miR-30a. qRT-PCR and western blotting were carried out to detect the relative expression of mRNAs and proteins. Cell cycle and cell apoptosis were determined by flow cytometry. Our results illustrated miR-30a could increase the radiosensitivity of NSCLC, especially in A549 cell line. In vivo experiment also showed the potential radiosensitizing possibility of miR-30a. Further exploration validated that miR-30a was directly targeting activating transcription factor 1 (ATF1). In studying the ataxia-telangiectasia mutated (ATM) associated effects on cell radiosensitivity, we found that miR-30a could reduce radiation induced G2/M cell cycle arrest and may also affect radiation induced apoptosis. Together, our results demonstrated that miR-30a may modulate the radiosensitivity of NSCLC through reducing the function of ATF1 in phosphorylation of ATM and have potential therapeutic value.