The use of cyclooxygenase-2 inhibitors for improvement of efficacy of radiotherapy in cancers

COX 2-inhibitors; a thorough and updated survey into combinational therapies in cancers

Cyclooxygenase (COX) enzymes are pivotal in inflammation and cancer development. COX-2, in particular, has been implicated in tumor growth, angiogenesis, and immune evasion. Recently, COX-2 inhibitors have arisen as potential therapeutic agents in cancer treatment. In addition, combining COX inhibitors with other treatment modalities has demonstrated the potential to improve therapeutic efficacy. This review aims to investigate the effects of COX inhibition, both alone and in combination with other methods, on signaling pathways and carcinogenesis in various cancers. In this study, a literature search of all major academic databases was conducted (PubMed, Scholar google), including the leading research on the mechanisms of COX-2, COX-2 inhibitors, monotherapy with COX-2 inhibitors, and combining COX-2-inhibitors with chemotherapeutic agents in tumors. The study encompasses preclinical and clinical evidence, highlighting the positive findings and the potential implications for clinical practice. According to preclinical studies, multiple signaling pathways implicated in tumor cell proliferation, survival, invasion, and metastasis can be suppressed by inhibiting COX. In addition, combining COX inhibitors with chemotherapy drugs, targeted therapies, immunotherapies, and miRNA-based approaches has enhanced anti-tumor activity. These results suggest that combination therapy has the potential to overcome resistance mechanisms and improve treatment outcomes. However, caution must be exercised when selecting and administering combination regimens. Not all combinations of COX-2 inhibitors with other drugs result in synergistic effects; some may even have unfavorable interactions. Therefore, personalized approaches that consider the specific characteristics of the cancer and the medications involved are crucial for optimizing therapeutic strategies. In conclusion, as monotherapy or combined with other methods, COX inhibition bears promise in modulating signaling pathways and inhibiting carcinogenesis in various cancers. Additional studies and well-designed clinical trials are required to completely elucidate the efficacy of COX inhibition and combination therapy in enhancing cancer treatment outcomes. This narrative review study provides a detailed summary of COX-2 monotherapy and combination targeted therapy in cancer treatment.

Bioprospecting-based untargeted metabolomics identifies alkaloids as potential anti-inflammatory bioactive markers of Ocotea species (Lauraceae)

BACKGROUND

Species within the Ocotea genus (Lauraceae), have demonstrated an interesting profile of bioactivities. Renowned for their diverse morphology and intricate specialized metabolite composition, Ocotea species have re-emerged as compelling candidates for bioprospecting in drug discovery research. However, it is a genus insufficiently studied, particularly regarding anti-inflammatory activity.

PURPOSE

To investigate the anti-inflammatory activity of Ocotea spp. extracts and determine the major markers in this genus.

METHODS

Extracts of 60 different Ocotea spp. were analysed by an ex vivo anti-inflammatory assay in human whole blood. The experiment estimates the prostaglandin E2 levels, which is one of the main mediators of the inflammatory cascade, responsible for the classical symptoms of fever, pain, and other common effects of the inflammatory process. Untargeted metabolomics analysis through liquid chromatography coupled with high-resolution mass spectrometry was performed, along with statistical analysis, to investigate which Ocotea metabolites are correlated with their anti-inflammatory activity.

RESULTS

The anti-inflammatory screening indicated that 49 out of 60 Ocotea spp. extracts exhibited significant inhibition of PGE2 release compared to the vehicle (p < 0.05). Furthermore, 10 of these extracts showed statistical similarity to the reference drugs. The bioactive markers were accurately identified using multivariate statistics combined with a fold change (> 1.5) and adjusted false discovery rate analysis as unknown compounds and alkaloids, with a majority of aporphine and benzylisoquinolines. These alkaloids were annotated with an increased level of confidence since MSE spectra were compared with comprehensive databases.

CONCLUSION

This study represents the first bioprospecting report revealing the anti-inflammatory potential of several Ocotea spp. The determination of their anti-inflammatory markers could contribute to drug discovery and the chemical knowledge of the Ocotea genus.

High throughput screen of small molecules as potential countermeasures to galactic cosmic radiation induced cellular dysfunction

Space travel increases galactic cosmic ray exposure to flight crews and this is significantly elevated once travel moves beyond low Earth orbit. This includes combinations of high energy protons and heavy ions such as ⁵⁶Fe or ¹⁶O. There are distinct differences in the biological response to low-energy transfer (x-rays) or high-energy transfer (High-LET). However, given the relatively low fluence rate of exposure during flight operations, it might be possible to manage these deleterious effects using small molecules currently available. Virtually all reports to date examining small molecule management of radiation exposure are based on low-LET challenges. To that end an FDA approved drug library (725 drugs) was used to perform a high throughput screen of cultured cells following exposure to galactic cosmic radiation. The H9c2 myoblasts, ES-D3 pluripotent cells, and Hy926 endothelial cell lines were exposed to a single exposure (75 cGy) using the 5-ion GCRsim protocol developed at the NASA Space Radiation Laboratory (NSRL). Following GCR exposure cells were maintained for up to two weeks. For each drug (@10µM), a hierarchical cumulative score was developed incorporating measures of mitochondrial and cellular function, oxidant stress and cell senescence. The top 160 scores were retested following a similar protocol using 1µM of each drug. Within the 160 drugs, 33 are considered to have an anti-inflammatory capacity, while others also indirectly suppressed pro-inflammatory pathways or had noted antioxidant capacity. Lead candidates came from different drug classes that included angiotensin converting enzyme inhibitors or AT1 antagonists, COX2 inhibitors, as well as drugs mediated by histamine receptors. Surprisingly, different classes of anti-diabetic medications were observed to be useful including sulfonylureas and metformin. Using a hierarchical decision structure, we have identified several lead candidates. That no one drug or even drug class was completely successful across all parameters tested suggests the complexity of managing the consequences of galactic cosmic radiation exposure.

Febuxostat, an inhibitor of xanthine oxidase, ameliorates ionizing radiation-induced lung injury by suppressing caspase-3, oxidative stress and NF-κB

Febuxostat (FBX), a selective inhibitor of xanthine oxidase, has several biological properties such as antioxidant, anti-inflammatory and anti-apoptosis activities. The purpose of this study was to evaluate the protective effect of FBX against ionizing radiation (IR)-induced lung injury through mitigation of oxidative stress, inflammation and apoptosis. Sixty-four mice were randomized into eight groups as control, FBX (5, 10, and 15 mg/kg), IR (6 Gy), and IR + FBX (IR + FBX in three doses). Mice were received FBX for 8 consecutive days and then were exposed to IR at a single dose (6 Gy) of X-ray. At 1 and 7 days after irradiation, the biochemical parameters were analyzed in lung tissue, while histological and immunohistochemical examinations were evaluated 1 week after irradiation. Irradiation led to elevate of oxidative stress parameters (an increase of MDA, PC, NO, and decrease of GSH), inflammation and apoptosis in lung of mice. Furthermore, IR resulted in histopathological changes in the lung tissues. These changes were significantly mitigated by FBX treatment. FBX also inhibited immunoreactivity of caspase-3, NF-κB, and reduced oxidative stress. This study showed that FBX is able to protect lung injury induced by IR through inhibiting apoptosis (caspase-3), oxidative stress and inflammation (NF-κB).

Beta-blockers disrupt mitochondrial bioenergetics and increase radiotherapy efficacy independently of beta-adrenergic receptors in medulloblastoma

Background

Medulloblastoma is the most frequent brain malignancy of childhood. The current multimodal treatment comes at the expense of serious and often long-lasting side effects. Drug repurposing is a strategy to fast-track anti-cancer therapy with low toxicity. Here, we showed the ability of β-blockers to potentiate radiotherapy in medulloblastoma with bad prognosis.

Methods

Medulloblastoma cell lines, patient-derived xenograft cells, 3D spheroids and an innovative cerebellar organotypic model were used to identify synergistic interactions between β-blockers and ionising radiations. Gene expression profiles of β-adrenergic receptors were analysed in medulloblastoma samples from 240 patients. Signaling pathways were explored by RT-qPCR, RNA interference, western blotting and RNA sequencing. Medulloblastoma cell bioenergetics were evaluated by measuring the oxygen consumption rate, the extracellular acidification rate and superoxide production.

Findings

Low concentrations of β-blockers significantly potentiated clinically relevant radiation protocols. Although patient biopsies showed detectable expression of β-adrenergic receptors, the ability of the repurposed drugs to potentiate ionising radiations did not result from the inhibition of the canonical signaling pathway. We highlighted that the efficacy of the combinatorial treatment relied on a metabolic catastrophe that deprives medulloblastoma cells of their adaptive bioenergetics capacities. This led to an overproduction of superoxide radicals and ultimately to an increase in ionising radiations-mediated DNA damages.

Interpretation

These data provide the evidence of the efficacy of β-blockers as potentiators of radiotherapy in medulloblastoma, which may help improve the treatment and quality of life of children with high-risk brain tumours.

Funding

This study was funded by institutional grants and charities.

Cytokeratin 13 promotes radiotherapy sensitivity of nasopharyngeal carcinoma by downregulating the MEK/ERK pathway

BACKGROUND

Radiation therapy is the first treatment choice for nasopharyngeal carcinoma (NPC), while radiation resistance and recurrence have become the primary factors and are associated with poor prognosis in the clinical treatment of NPC patients. The purpose of the present study was to explore the sensitivity and molecular basis of cytokeratin 13 (CK13) that regulates NPC radiotherapy.

METHODS

HNE-3 or C666-1 cell line was used for overexpression and knockdown tests. Under radiotherapy conditions, CCK-8 assay, clone formation assay, and flow cytometry analyzed the effects of CK13 overexpression on cell proliferation, apoptosis, and cell cycle, respectively. In addition, Western blotting detected CK13-mediated downregulation of cell cycle-related genes. The mouse subcutaneous tumor-bearing experiment identified the effects of CK13 overexpression on the treatment of NPC in vivo. Further, Western blotting, CCK-8 assay, and flow cytometry investigated whether the CK13-mediated cell apoptosis involves the MEK/ERK signaling pathway.

RESULTS

Overexpression of CK13 significantly inhibited the survival of HNE-3 cells under radiotherapy in vitro and in vivo, and there was a substantial decrease in cyclin-dependent kinase 4 and 6 (CDK4/6) levels promoting the cell percentage number in the G2/M phase and, subsequently, the ratio of the apoptotic cells. In contrast, the knockdown of CK13 showed the opposite partial regulatory effect. Interestingly, CK13 overexpression also showed a reduction in the survival of C666-1 cells and an increased ratio of the apoptotic cells under radiotherapy treatment. Furthermore, higher levels of CK13 downregulated the MEK/ERK signaling pathway, resulting in decreased HNE-3 cell proliferation and increased apoptosis. However, ERK activators were able to rescue the process partially.

CONCLUSIONS

Together, these results showed that CK13 promoted the radiosensitivity of NPC cells by downregulating the MEK/ERK signaling pathway. Thus, targeting CK13 provided insights into the treatment of NPC radiotherapy.

Sphingosine 1-Phosphate-Upregulated COX-2/PGE2 System Contributes to Human Cardiac Fibroblast Apoptosis: Involvement of MMP-9-Dependent Transactivation of EGFR Cascade

Human cardiac fibroblasts (HCFs) play key roles in normal physiological functions and pathological processes in the heart. Our recent study has found that, in HCFs, sphingosine 1-phosphate (S1P) can upregulate the expression of cyclooxygenase-2 (COX-2) leading to prostaglandin E2 (PGE2) generation mediated by S1P receptors/PKCα/MAPKs cascade-dependent activation of NF-κB. Alternatively, G protein-coupled receptor- (GPCR-) mediated transactivation of receptor tyrosine kinases (RTKs) has been proved to induce inflammatory responses. However, whether GPCR-mediated transactivation of RTKs participated in the COX-2/PGE2 system induced by S1P is still unclear in HCFs. We hypothesize that GPCR-mediated transactivation of RTKs-dependent signaling cascade is involved in S1P-induced responses. This study is aimed at exploring the comprehensive mechanisms of S1P-promoted COX-2/PGE2 expression and apoptotic effects on HCFs. Here, we used pharmacological inhibitors and transfection with siRNA to evaluate whether matrix metalloprotease (MMP)2/9, heparin-binding- (HB-) epidermal growth factor (EGF), EGF receptor (EGFR), PI3K/Akt, MAPKs, and transcription factor AP-1 participated in the S1P-induced COX-2/PGE2 system determined by Western blotting, real-time polymerase chain reaction (RT-PCR), chromatin immunoprecipitation (ChIP), and promoter-reporter assays in HCFs. Our results showed that S1PR1/3 activated by S1P coupled to Gq- and Gi-mediated MMP9 activity to stimulate EGFR/PI3K/Akt/MAPKs/AP-1-dependent activity of transcription to upregulate COX-2 accompanied with PGE2 production, leading to stimulation of caspase-3 activity and apoptosis. Moreover, S1P-enhanced c-Jun bound to COX-2 promoters on its corresponding binding sites, which was attenuated by these inhibitors of protein kinases, determined by a ChIP assay. These results concluded that transactivation of MMP9/EGFR-mediated PI3K/Akt/MAPKs-dependent AP-1 activity was involved in the upregulation of the COX-2/PGE2 system induced by S1P, in turn leading to apoptosis in HCFs.

Mefenamic acid as a promising therapeutic medicine against colon cancer in tumor-bearing mice

Although radiotherapy is an effective strategy for cancer treatment, tumor resistance to ionizing radiation (IR) and its toxic effects on normal tissues are limiting its use. The aim of this study is to evaluate the anti-cancer effects of mefenamic acid (MEF), as an approved medicine, and its combination with IR against colon tumor cells in mice. Tumor-bearing mice were received MEF at a dose of 25 mg/kg for 6 successive days. The tumor size was measured. In the second experiment, after MEF treatment, tumor-bearing mice locally received an X-ray at dose 6 Gy. Tumor growth and biochemical, histological, and immunohistological assay (caspase-3) were performed. MEF significantly decreased tumor size in mice in comparison to the control group. IR and/or MEF treatment significantly reduced the tumor volume and inhibited tumor growth by 49%, 55%, and 67% by MEF, IR, and MEF + IR groups as compared with the control group. Administration of MEF in combination with radiation had a synergistic effect on enhanced histopathological changes in tumor tissues. MEF treatment in IR exposure mice showed a significant increase in the immunoreactivity of caspase-3 in the colon tumor tissue. MEF has an anti-tumor effect in colon tumor-bearing mice. MEF in combination with IR increased pathological changes and apoptosis in tumor tissues, suggesting that MEF might be clinically useful in the treatment of colon cancer.

Elucidating the mechanisms of action of parecoxib in the MG-63 osteosarcoma cell line

Different types of tumors often present an overexpression of cyclooxygenase-2. The aim of this study was to evaluate the effects of parecoxib (NSAID, cyclooxygenase-2 selective inhibitor) in the behavior of the human osteosarcoma MG-63 cell line, concerning several biological features. Cells were exposed to several concentrations of parecoxib for 48 hours. Cell viability/proliferation, cyclooxygenase-2 expression, morphologic alterations, membrane integrity, cell cycle evaluation, cell death and genotoxicity were evaluated. When compared with untreated cells, parecoxib led to a marked decrease in cell viability/proliferation, in COX-2 expression and changes in cell morphology, in a concentration-dependent manner. Cell recuperation was observed after incubation with drug-free medium. Parecoxib exposure increased lactate dehydrogenase release, an arrest of the cell cycle at S-phase and G2/M-phase, as well as growth of the sub-G0/G1-fraction and increased DNA damage. Parecoxib led to a slight increase of necrosis regulated cell death in treated cells, and an increase of autophagic vacuoles, in a concentration-dependent manner. In this study, parecoxib showed antitumor effects in the MG-63 human osteosarcoma cells. The potential mechanism was inhibiting cell proliferation and promoting necrosis. These results further suggested that parecoxib might be a potential candidate for in-vivo studies.

Pathomechanisms and therapeutic opportunities in radiation-induced heart disease: from bench to bedside

Cancer management has undergone significant improvements, which led to increased long-term survival rates among cancer patients. Radiotherapy (RT) has an important role in the treatment of thoracic tumors, including breast, lung, and esophageal cancer, or Hodgkin's lymphoma. RT aims to kill tumor cells; however, it may have deleterious side effects on the surrounding normal tissues. The syndrome of unwanted cardiovascular adverse effects of thoracic RT is termed radiation-induced heart disease (RIHD), and the risk of developing RIHD is a critical concern in current oncology practice. Premature ischemic heart disease, cardiomyopathy, heart failure, valve abnormalities, and electrical conduct defects are common forms of RIHD. The underlying mechanisms of RIHD are still not entirely clear, and specific therapeutic interventions are missing. In this review, we focus on the molecular pathomechanisms of acute and chronic RIHD and propose preventive measures and possible pharmacological strategies to minimize the burden of RIHD.

Celecoxib and Afatinib synergistic enhance radiotherapy sensitivity on human non-small cell lung cancer A549 cells

PURPOSE

Radioresistance is highly correlated with radiotherapy failure in clinical cancer treatment. In the current study, we sought to examine the efficacy of Celecoxib and Afatinib co-treatment as radiosensitizers in the management of non-small cell lung cancer (NSCLC) A549 cells.

MATERIALS AND METHODS

Generally, A549 cells were cultured with the treatment of Celecoxib and/or Afatinib for 24 h. Then, the cells were exposed to irradiation at 2 Gy/min for 1 min. After the end of treatment, cell viability, clonogenic survival, apoptosis and Prostaglandin E2 (PGE2) Elisa assays were performed. Transcriptional levels of Cyclooxygenase-2 (COX-2) affected by Celecoxib and/or Afatinib were measured by RT-qPCR. Posttranscriptional level of epidermal growth factor receptor (EGFR)-related gene was measured by Western blotting analysis.

RESULTS

Here, we, for the first time, reported that the co-treatment of Celecoxib and Afatinib regulates the resistance of NSCLC A549 cells to radiation. The co-treatment of Celecoxib and Afatinib sensitized radiotherapy through the radiation-induced loss of cell viability and colony formation, as well as apoptosis. Mechanistically, Celecoxib and Afatinib-treated cells showed the inhibition of COX-2 and EGFR expression, which may be responsible for the A549 cells' increased resistance to radiation.

CONCLUSION

Our results suggested that Celecoxib and Afatinib regulate cell sensitivity to apoptosis, and thus modulate the resistance of NSCLC to radiation.

CDK4/6 inhibitors: a novel strategy for tumor radiosensitization

Recently, the focus of enhancing tumor radiosensitivity has shifted from chemotherapeutics to targeted therapies. Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors are a novel class of selective cell cycle therapeutics that target the cyclin D-CDK4/6 complex and induce G1 phase arrest. These agents have demonstrated favorable effects when used as monotherapy or combined with endocrine therapy and targeted inhibitors, stimulating further explorations of other combination strategies. Multiple preclinical studies have indicated that CDK4/6 inhibitors exhibit a synergistic effect with radiotherapy both in vitro and in vivo. The principal mechanisms of radiosensitization effects include inhibition of DNA damage repair, enhancement of apoptosis, and blockade of cell cycle progression, which provide the rationale for clinical use. CDK4/6 inhibitors also induce cellular senescence and promote anti-tumor immunity, which might represent potential mechanisms for radiosensitization. Several small sample clinical studies have preliminarily indicated that the combination of CDK4/6 inhibitors and radiotherapy exhibited well-tolerated toxicity and promising efficacy. However, most clinical trials in combined therapy remain in the recruitment stage. Further work is required to seek optimal radiotherapy-drug combinations. In this review, we describe the effects and underlying mechanisms of CDK4/6 inhibitors as a radiosensitizer and discuss previous clinical studies to evaluate the prospects and challenges of this combination.

Radioprotective Effect of Pioglitazone Against Genotoxicity Induced by Ionizing Radiation in Healthy Human Lymphocytes

OBJECTIVE

Pioglitazone (PG) is used to control high blood sugar in patients with type 2 diabetes mellitus. PG acts as a peroxisome proliferator-activated receptor γ agonist. In addition to the insulin-sensitizing effect, PG possesses anti-inflammatory effect. In this study, the protective effect of PG was evaluated against DNA damage induced by ionizing radiation in healthy human lymphocytes.

METHODS

The microtubes containing human whole blood were treated with PG at various concentrations (1-50 μM) for three hours. Then, the blood samples were irradiated with X-ray. Lymphocytes were cultured for determining the frequency of micronuclei as a genotoxicity biomarker in binucleated lymphocytes.

RESULTS

The mean percentage of micronuclei was significantly increased in human lymphocytes when exposed to IR, while it was decreased in lymphocytes pre-treated with PG. The maximum reduction in the frequency of micronuclei in irradiated lymphocytes was observed at 5 μM of PG treatment (48% decrease).

CONCLUSION

The anti-inflammatory property suggested the mechanism action of PG for protecting human lymphocytes against genotoxicity induced by ionizing radiation.

Fluoxetine as an antidepressant medicine improves the effects of ionizing radiation for the treatment of glioma

Radiotherapy is a cancer treatment protocol which delivers high dose of ionizing radiation (IR) to tumor. Tumor resistance and side effects induced by IR still are the major challenges in radiotherapy. The purpose of this study was to evaluate the synergistic killing effect of fluoxetine (FL) with IR on glioma cancer cell (U-87 MG), as well as radioprotective effect of FL against cellular toxicity induced by IR on non-malignant human fibroblast cell (HFFF2). Firstly, the inhibitory effects of FL on cell proliferations were evaluated in U-87 MG and HFFF2 cells. The clonogenic and MTT assays were used to evaluate the radiosensitivity and radioprotective effects of FL on cancer and non-malignant cells. The frequencies of apoptotic cells were evaluated by flow cytometry on both cancer and normal cells. Results showed that FL exhibited anti-cancer effect on glioma cells, while cellular toxicity was low in HFFF2 cells treated with FL. FL decreased the viable colonies and enhanced apoptotic cells when U-87 cells were treated with FL prior irradiation. For comparison, FL exhibited radioprotective effect through increasing cellular proliferation rate and reducing apoptosis in HFFF2 cells against IR. The results showed that FL enhanced the IR-induced glioma cancer cell death and apoptosis, whereas it exhibited a radioprotective effect on normal fibroblast cells suggesting that FL administration may improve glioma radiotherapy.

Radiosensitivity enhancement by Co-NMS-mediated mitochondrial impairment in glioblastoma

We investigated the radiosensitizing effects of Co-NMS, a derivative of nimesulide based on a cobalt carbonyl complex, on malignant glioma cells. In the zebrafish exposed to Co-NMS ranging from 5 to 20 μM, cell death and heat shock protein 70 expression in the brain and neurobehavioral performance were evaluated. Our data showed that Co-NMS at 5 μM did not cause the appreciable neurotoxicity, and thereby was given as a novel radiation sensitizer in further study. In the U251 cells, Co-NMS combined with irradiation treatment resulted in significant inhibition of cell growth and clonogenic capability as well as remarkable increases of G2/M arrest and apoptotic cell population compared to the irradiation alone treatment. This demonstrated that the Co-NMS administration exerted a strong potential of sensitizing effect on the irradiated cells. With regard to the tumor radiosensitization of Co-NMS, it could be primarily attributed to the Co-NMS-derived mitochondrial impairment, reflected by the loss of mitochondrial membrane potential, the disruption of mitochondrial fusion and fission balance as well as redox homeostasis. Furthermore, the energy metabolism of the U251 cells was obviously suppressed by cotreatment with Co-NMS and irradiation through repressing mitochondrial function. Taken together, our findings suggested that Co-NMS could be a desirable drug to enhance the radiotherapeutic effects in glioblastoma patients.

In-vivo and In-vitro Antioxidant Activity of Troxerutin on Nickel Induced Toxicity in Experimental Rats

The aim of the present study was to evaluate the effect of troxerutin (TXN) on Nickel (Ni) toxicity by using rats and in-vitro model. Ni toxicity induced in male albino wistar rats (20 mg/kg body weight (b.w) was administered orally for 20 days). TXN was administered orally (100 mg/kg (b.w) for 20 days with administration of Ni. The toxic effect of Ni and the action of TXN was measure by determining the lipid peroxidation markers and antioxidant levels in plasma and various in-vitro antioxidant systems. TXN exhibited a significant (p < 0.05) antioxidant activity in Ni induced toxicity by reversing the changes observed in TBARS, HP, Vitamin C, E and GSH. The free radical scavenging properties of TXN at different concentrations (10-50ug/mL) were investigated with various in-vitro methods such as 2, 2'-diphenyl-1- picrylhydrazyl radical (DPPH), 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS•+), hydroxyl radical, superoxide anion scavenging activity and reducing power. Among the different concentrations, 50 μg/mL of TXN was more effective compared to other concentrations in all in-vitro assays. The above study conclude that TXN possesses potent in-vivo and in-vitro antioxidant activity with effective free radical scavenger for potential therapeutic value.

Radioprotective effect of diethylcarbamazine on radiation-induced acute lung injury and oxidative stress in mice

The present study was designed to evaluate the radioprotective effect of diethylcarbamazine (DEC) against oxidative stress and acute lung injury induced by total body radiation (TBI) in mice. For study the optimum dose for radiation protection of DEC, mice were administrated with three dose of DEC (10, 50 and 100 mg/kg), once daily for eight consecutive days. Animals were exposed whole body to 5 Gy X-radiation on the 9 day. The radioprotective potential of DEC in lung tissues was assessed using oxidative stress examinations at 24 h after TBI and histopathological assay also was analyzed one week after TBI. Results from biochemical analyses demonstrated increased malonyldialdehyde (MDA), nitric oxide (NO) and protein carbonyl (PC) levels of lung tissues in only irradiated group. Histopathologic findings also showed an increase in the number of inflammatory cells and the acute lung injury in this group. DEC pretreatment significantly mitigated the oxidative stress biomarkers as well as histological damages in irradiated mice. The favorable radioprotective effect against lungs injury was observed at a dose of 10 mg/kg of DEC in mice as compared with two other doses (50 and 100 mg/kg). The data of this study showed that DEC at a dose of 10 mg/kg with having antioxidant and anti-inflammatory properties can be used as a therapeutic candidate for protecting the lung from radiation-induced damage.

Radioprotective Potential of Sulindac Sulfide to Prevent DNA Damage Due to Ionizing Radiation

Introduction: The ionizing radiation exposure of the normal cell causes damage to DNA, which leads to cell dysfunction or even cell death. However, it is necessary to identify new radio protectives in order to protect normal cells. Sulindac sulfide (SS) is a metabolite of sulindac (a non-steroidal anti-inflammatory drug) known as a cyclooxygenase inhibitor. Free radicals and reactive oxygen species are generated in the IR-exposed cells. Also, the induced inflammation process causes damage in DNA.

Purpose

In this research, the radioprotective effect of SS was investigated against genotoxicity and lipid peroxidation induced by ionizing radiation in the human blood lymphocytes.

Methods

In this study, the human blood samples were pretreated with SS at different concentrations (10, 25, 50, 100 and 250 μM) and then were exposed to IR at a dose of 1.5 Gy. The micronucleus (MN) assay was used to indicate the radioprotective effects of SS on exposed cells. Total antioxidant activity of the SS was measured by using FRAP and DPPH assay. Also, the malondialdehyde (MDA) levels and the activity of superoxide dismutase (SOD) on the exposed cells were evaluated.

Results

It was found that SS decreased the percentage of MN induced by IR in exposed cells. Maximum reduction in the frequency of MN was observed at 250 μM of SS (87%) that provides the highest degree of protection against IR. On the other hand, pretreatment at 250 μM of SS inhibited IR-induced oxidative stress, which led to a decrease in the MN frequencies and MDA levels, while SOD activity showed an increase in the exposed cells.

Conclusion

It could be concluded that SS as a good radioprotective agent protects the human normal cells against the oxidative stress and genetic damage induced by IR.

Human disorders associated with inflammation and the evolving role of natural products to overcome

Inflammation is a biological function which triggered after the mechanical tissue disruption or from the responses by the incidence of physical, chemical or biological negotiator in body. These responses are essential act provided by the immune system during infection and tissue injury to maintain normal tissue homeostasis. Inflammation is a quite complicated process at molecular level with the involvement of several proinflammatory expressions. Several health problems are associated with prolonged inflammation, which effects nearly all major to minor diseases. The molecular and epidemiological studies jagged that the inflammation is closely associated with several disorders with their specific targets. It would be great achievement for human health around the world to overcome on inflammation. Mostly used anti-inflammatory drugs are at high risk of side effects and also expensive. Hence, the plant-based formulations gained a wide acceptance by the public and medical experts to treat it. Due to extensive dispersal, chemical diversity and systematically established biological potentials of natural products have induced renewed awareness as a gifted source for medications. However, today's urgent need to search for cheaper, more potent and safe anti-inflammatory medications to overcome on current situation. The goal of this review to compile an update on inflammation, associated diseases, molecular targets, inflammatory mediators and role of natural products. The entire text concise the involvement of various cytokines in pathogenesis of various human disorders. This assignment discussed about 321 natural products with their promising anti-inflammatory potential discovered during January 2009 to December 2018 with 262 citations.

Molecular mechanisms of anti-psychotic drugs for improvement of cancer treatment

Anti-psychotic medications are widely used to treat schizophrenia and bipolar disorder. Besides their medical applications, anti-psychotic drugs have other pharmacological properties which are involved in multiple intracellular functions including metabolism, cell stress, cell-cycle regulation, survival and apoptosis through modulation of cellular signaling pathways such as PI3K/Akt/GSK-3β, STAT3 and wingless (Wnt)-related intracellular signaling. Also, anti-psychotics counteract the growth of tumor cells by stimulating the cellular immune system and natural killer cells. On the other hand, the positive charge and the lipophilicity of anti-psychotics have significant roles in the inhibition of P-gp pumps resulting in accumulation of chemotherapy drugs as well as increasing the cellular susceptibility to chemotherapy, autophagy, angiogenesis inhibition, stem cells differentiation induction and changing the expression of tumor suppressor genes and oncogenes. Overall, anti-psychotics are able to inhibit the proliferation of cancer cells through modulation of different cellular pathways. Anti-psychotics act as anti-cancer drugs and besides can increase the efficacy of anti-cancer agents in cancer cells. In this study, the anti-cancer effects of different anti-psychotic medicines on various malignant tumor cells and their molecular mechanisms have been discussed.

Screening and isolation of cyclooxygenase-2 inhibitors from Trifolium pratense L. via ultrafiltration, enzyme-immobilized magnetic beads, semi-preparative high-performance liquid chromatography and high-speed counter-current chromatography

Nonsteroidal anti-inflammatory drugs reportedly reduce the risk of developing cancer. One mechanism by which they reduce carcinogenesis involves the inhibition of the activity of cyclooxygenase-2, an enzyme that is overexpressed in various cancer tissues. Its overexpression increases cell proliferation and inhibits apoptosis. However, selected cyclooxygenase-2 inhibitors can also act through cyclooxygenase-independent mechanisms. In this study, using ultrafiltration, enzyme-immobilized magnetic beads, high-performance liquid chromatography, and electrospray-ionization mass spectrometry, several isoflavonoids in Trifolium pratense L. extracts were screened and identified. Semi-preparative high-performance liquid chromatography and high-speed counter-current chromatography were then applied to separate the active constituents. Using these methods, seven major compounds were identified in Trifolium pratense L. As cyclooxygenase-2 inhibitors: rothindin, ononin, daidzein, trifoside, pseudobaptigenin, formononetin, and biochanin A, which were then isolated with >92% purity. This is the first report of the presence of potent cyclooxygenase-2 inhibitors in Trifolium pratense L. extracts. The results of this study demonstrate that the systematic isolation of bioactive components from Trifolium pratense L., by using ultrafiltration, enzyme-immobilized magnetic beads, semi-preparative high-performance liquid chromatography, and high-speed counter-current chromatography, represents a feasible and efficient technique that could be extended for the identification and isolation of other enzyme inhibitors.

Activation of PTGS2/NF-κB signaling pathway enhances radiation resistance of glioma

Objective

We focused on the effects of PTGS2/NF‐κB signaling pathway on the radiation resistance of glioma in the study.

Methods

We downloaded the microarray data from the Gene Expression Omnibus (GEO) database. We verified transfection successfully through QRT‐PCR analysis. Immunofluorescence was used to detect γH2AX content under 2 Gy radiation. The survival rates of cells under 2 Gy irradiation were tested by clonogenic survival assay. Flow cytometry was used to detect cell cycle. Western blot was applied to detect the expression of NF‐κB pathway‐related proteins. We also used MTT assay to detect the proliferation of cells.

Results

In this research, we discovered that the expression of the PTGS2 was upregulated in radiation‐resistant glioma cells. The radio‐tolerance rate of U87 cells was obviously elevated after the overexpression of PTGS2. The radioresistance of U87R cells was significantly reduced after the knockdown of PTGS2. After radiotherapy, the number of cells arrested in G2/M phase decreased after PTGS2 overexpression in U87cells but increased in PTGS2 knockdown in U87R cells. The survival rate of U87 and U87R cells under radiation decreased significantly after the addition of NF‐κB inhibitor. The proliferation of U87 cells was suppressed by radiation and the addition of Bay 11. In addition, PTGS2 activated NF‐κB signaling pathway and prevented DNA damage after radiotherapy. Lastly, PTGS2 was proved to facilitate tumor cell proliferation and improve the radio‐tolerance.

Conclusion

PTGS2/NF‐κB signaling pathway was involved in radio‐tolerance of glioma cells, which provided a new insight into glioma therapy.

Mediators of Inflammation - A Potential Source of Biomarkers in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common tumour of the oral cavity, associated with significant morbidity and mortality. It is a multifactorial condition, both genetic and environmental factors being involved in its development and progression. Its pathogenesis is not fully elucidated, but a pivotal role has been attributed to inflammation, strong evidence supporting the association between chronic inflammation and carcinogenesis. Moreover, an increasing number of studies have investigated the role of different mediators of inflammation in the early detection of OSCC. In this review, we have summarized the main markers of inflammation that could be useful in diagnosis and shed some light in OSCC pathogenesis.

Cyclooxygenase-2 in cancer: A review

Cyclooxygenase-2 (COX-2) is frequently expressed in many types of cancers exerting a pleiotropic and multifaceted role in genesis or promotion of carcinogenesis and cancer cell resistance to chemo- and radiotherapy. COX-2 is released by cancer-associated fibroblasts (CAFs), macrophage type 2 (M2) cells, and cancer cells to the tumor microenvironment (TME). COX-2 induces cancer stem cell (CSC)-like activity, and promotes apoptotic resistance, proliferation, angiogenesis, inflammation, invasion, and metastasis of cancer cells. COX-2 mediated hypoxia within the TME along with its positive interactions with YAP1 and antiapoptotic mediators are all in favor of cancer cell resistance to chemotherapeutic drugs. COX-2 exerts most of the functions through its metabolite prostaglandin E2. In some and limited situations, COX-2 may act as an antitumor enzyme. Multiple signals are contributed to the functions of COX-2 on cancer cells or its regulation. Members of mitogen-activated protein kinase (MAPK) family, epidermal growth factor receptor (EGFR), and nuclear factor-κβ are main upstream modulators for COX-2 in cancer cells. COX-2 also has interactions with a number of hormones within the body. Inhibition of COX-2 provides a high possibility to exert therapeutic outcomes in cancer. Administration of COX-2 inhibitors in a preoperative setting could reduce the risk of metastasis in cancer patients. COX-2 inhibition also sensitizes cancer cells to treatments like radio- and chemotherapy. Chemotherapeutic agents adversely induce COX-2 activity. Therefore, choosing an appropriate chemotherapy drugs along with adjustment of the type and does for COX-2 inhibitors based on the type of cancer would be an effective adjuvant strategy for targeting cancer.

Topical atorvastatin 1% for prevention of skin toxicity in patients receiving radiation therapy for breast cancer: a randomized, double-blind, placebo-controlled trial

BACKGROUND AND PURPOSE

The purpose of this randomized, placebo-controlled, double-blind study was to investigate the preventive effect of topical administration of atorvastatin (ATV) on the acute radiation-induced skin toxicity in patients with breast cancer.

PATIENTS AND METHODS

Seventy breast cancer patients were randomly assigned to use topical ATV 1% or placebo gels during radiotherapy twice daily. Radiation-induced dermatitis was classified according to the radiation therapy oncology group (RTOG) criteria, as well as pain and itching were scored according to VAS (visual analogue scale) for 6 weeks of treatment.

RESULTS

Topical administration of ATV gel during radiotherapy reduced significantly radiation-induced breast swelling, itching, and pain in breast cancer patients by factors of 1.8, 1.7, and 1.5, respectively. ATV reduced the redness caused by radiotherapy in patients as compared with placebo; however, this difference was statistically not significant.

CONCLUSION

ATV was able to reduce significantly itching, breast edema, and pain in patients during radiotherapy.

Preventative effect of celecoxib in dimethylbenz[a]anthracene-induced ovarian cancer in rats

PURPOSE

The present study investigated the preventive effect of the cyclooxygenase (COX)-2 inhibitor, celecoxib, in 7,12-dimethylbenz[a]anthracene (DMBA)-induced ovarian cancer in a rat model.

METHODS

A diet containing celecoxib (1500 ppm) was started 2 weeks before the introduction of DMBA. DMBA-soaked cotton threads were surgically applied to induce ovarian cancer in female Wistar rats. Tumor growth and survival were observed for 24 weeks.

RESULTS

During the study period, an overall tumor incidence of 97.5% was observed and 65% of tumors were ovarian adenocarcinoma. The celecoxib diet significantly reduced the incidence and size of DMBA-induced ovarian cancers and significantly improved survival of tumor-bearing rats. The preventive effect of celecoxib was associated with increased apoptosis.

CONCLUSION

DMBA-induced ovarian cancer in rats recapitulates many pathophysiological features of the human counterpart. Our results provide supportive evidence that celecoxib has a preventive effect on development of ovarian cancer in a rat model.

Cyclooxygenase‑2‑mediated upregulation of heme oxygenase 1 mitigates the toxicity of deuterium‑tritium fusion radiation

Utilizing the energy released from the nuclear fusion of deuterium with tritium (D-T) may be an important method of supplying energy in the future. The ionizing radiation emitted from nuclear fusion is a potential health risk to humans, including scientists who are currently performing nuclear fusion experiments and the employees of fusion nuclear plants, in the future. However, there have been few reports on the biological effects of fusion radiation. In the present study, using the High Intensity D-T Fusion Neutron Generator, the DNA damage and its regulation in normal human fibroblasts exposed to fusion radiation were investigated. Heme oxygenase 1 (HO-1), which is reported to induce anti-inflammatory activity, was upregulated in the irradiated cells. Pretreatment with the HO-1 inhibitor, protoporphyrin IX zinc (II), exacerbated double strand break formation following exposure to fusion radiation. The expression of cyclooxygenase-2 (COX-2) contributed to the upregulation of HO-1, as demonstrated by the result that its inhibitor, NS-398, inhibited the induction of HO-1 in irradiated cells. It was further clarified that the ataxia telangiectasia mutated DNA damage response was activated and it stimulated the phosphorylation of p38 mitogen-activated protein kinase, which was responsible for the upregulation of COX-2 and HO-1. These results provide novel information on fusion radiation-induced biological effects and potential targets for decreasing the associated health risks.

Radiosensitizing effects of different size bovine serum albumin-templated gold nanoparticles on H22 hepatoma-bearing mice

Aim: To evaluate intravenously injected bovine serum albumin-templated gold nanoparticles (BSA-GNPs) for radiosensitization effects on H22 hepatoma-bearing mice. Materials & methods: BSA-GNPs in different size were injected intravenously with a dose of 4 mg Au/kg. After 30 min injection, the tumor-bearing mice were irradiated with 5 Gy x-ray. Results: BSA-GNPs in 8, 50 and 187 nm were synthesized and have no obvious cytotoxicity to HeLa, HepG2 and HeCat cells when the concentration was up to 32 μM. And no obvious physiological injury of mice occurred when the intravenous injection dose was 4 mg Au/kg. In vivo study indicates 8 and 50 nm BSA-GNPs can inhibit tumor growth through inducing apoptosis in radiotherapy, with enhancement factors 1.93 and 2.02, respectively. Conclusion: BSA-GNPs in 8 and 50 nm are promising radiosensitizers in radiotherapy of subcutaneously transplanted hepatocarcinoma.

Simultaneous determination of parecoxib and its main metabolites valdecoxib and hydroxylated valdecoxib in mouse plasma with a sensitive LC-MS/MS method to elucidate the decreased drug metabolism of tumor bearing mice

Parecoxib (PX), a prodrug of valdecoxib (VX), is an injectable selective COX-2 inhibitor, and is recommended for the treatment of cancer pain. PX can be rapidly hydrolyzed into its active metabolite VX, and VX is further metabolized into hydroxylated valdecoxib (OH-VX) by cytochrome P450 enzymes. However, cancer patients have been reported to possess reduced drug metabolism ability, which might cause excessive drug accumulation. Such overdose of PX significantly increased the risk of renal safety and cardiovascular events. Therefore, it is necessary to elucidate the concentration profiles of PX and its metabolites in cancer status. In this study, a sensitive, rapid and specific LC-MS/MS method for quantification of PX, VX and OH-VX in the plasma of tumor bearing mouse was developed and validated. After protein precipitation, all the analytes were separated on an Agilent ZORBAX Extend-C18 HPLC column (2.1 × 100 mm, 3.5 μm) with gradient elution. The analytes were detected by an electrospray negative ionization mass spectrometry in the multiple reaction monitoring mode. The transition m/z 369.0 → 119.0, m/z 312.9 → 117.9, m/z 329.0 → 196.0, and m/z 307.1 → 161.3 were used for monitoring PX, VX, OH-VX and IS respectively. The calibration curves of the analytes showed good linearity over the concentration range of 3-3000 ng/mL for PX and VX, and 3-1000 ng/mL for OH-VX. Intra- and inter-batch accuracies (in terms of relative error, RE < 9.9%) and precisions (in terms of relative standard deviation, RSD < 8.8%) satisfied the standard of validation. The matrix effect, recovery and stability were also within acceptable criteria. The method was successfully applied to the pharmacokinetics study of PX in tumor bearing mice, and PX and VX levels were found elevated with the growth of tumor volume, which might increase the risk of drug overdose.

The role of propranolol as a radiosensitizer in gastric cancer treatment

Purpose

The National Comprehensive Cancer Network guidelines indicate that radiotherapy in gastric cancer shows limited effectiveness at reducing the growth of gastric cancer. Therefore, enhancing the sensitivity and effect of radiotherapy with propranolol, a β-adrenoceptor antagonist, could reduce tumor growth. The role of propranolol as a radiosensitizer has not been adequately studied; therefore, the purpose of the present study is to evaluate the effect of propranolol as a radiosensitizer against gastric cancer in vivo.

Methods

Sixty-four male nude mice bearing tumor xenografts were randomly divided into four groups. Cell culture was performed using the human gastric adenocarcinoma cell line SGC-7901. Mice with tumor xenografts were treated with propranolol, isoproterenol, and radiation. The data for tumor weight and volume were obtained for statistical analyses. Furthermore, the expression levels of COX-2, NF-κB, VEGF, and EGFR were examined using immunohistochemical techniques and Western blotting.

Results

The growth in the volume and weight of the tumor was lower in mouse models treated with propranolol and radiation therapy compared to the other groups. Decreased expression of NF-κB was also observed in treatment groups where both propranolol and radiation were used, leading to the reduction of COX-2, EGFR, and VEGF expression compared to that in the other groups.

Conclusion

The present study indicated that propranolol potentiates the antitumor effects of radiotherapy in gastric cancer by inhibiting NF-κB expression and its downstream genes: VEGF, EGFR, and COX-2.

Synergistic antitumor effects of the combined treatment with an HDAC6 inhibitor and a COX-2 inhibitor through activation of PTEN

Chemotherapy is one of the most effective non-surgical treatments for various types of tumor. Identifying different combinations of antitumor agents that can produce synergistic antitumor effects remains an important clinical strategy. In the present study, we showed that the combination of histone deacetylase 6 (HDAC6) inhibitor tubastatin A together with cyclooxygenase-2 (COX-2) inhibitor celecoxib resulted in synergistic antitumor effects in CAL 27 and SACC-83 cells. Treatment with celecoxib alone promoted the membrane translocation of phosphatase and tensin homolog (PTEN), indicating PTEN activation, and consequently led to protein kinase B (AKT) dephosphorylation (inactivation). Similarly, treatment with an HDAC6 inhibitor alone promoted PTEN membrane translocation and correspondingly dephosphorylated AKT. The combination of celecoxib and an HDAC6 inhibitor synergistically increased PTEN membrane translocation and inactivated AKT. Moreover, celecoxib enhanced the HDAC6 inhibitor-induced antitumor effects in PTEN-deficient U-87 MG cells that had been stably transfected with wild-type PTEN, but not in the same cell line stably transfected with mutant PTEN-K163R, which cannot be activated by HDAC6 inhibitors. In summary, the results indicated that the COX-2 inhibitor celecoxib enhanced the HDAC6 inhibitor-induced antitumor effects by activating the PTEN/AKT signaling pathway.

Evaluation of human glioma using in-vivo proton magnetic resonance spectroscopy combined with expression of cyclooxygenase-2: a preliminary clinical trial

We sought to investigate the correlation between in-vivo proton magnetic resonance spectroscopy (H-MRS) and cyclooxygenase-2 (COX-2) expression in human glioma, and to advance their roles in diagnostic mapping and monitoring of glioma biological behavior. Thirty-nine patients with different grades of glioma (WHO classification I-IV) included in this study were scanned at 3.0 T MR before operation or biopsy puncture. Tumor morphology and H-MRS metabolites ratio [choline (Cho)/creatine (Cr)] were evaluated independently by two experienced radiologists. Paraffin-embedded glioma specimens were detected for the COX-2 expression using immunohistochemistry. Parametric and nonparametric tests including correlation, logistic regression and receiver operating characteristic analysis were applied to assess the predicative roles and relation diagram of H-MRS and COX-2. The COX-2 expression showed a significant difference between low and high grade gliomas (P<0.01). Varying degrees of COX-2 expression have positive correlation with the Cho/Cr values in tumor zone (r=0.49, P=0.013), and showed not significant correlation with sex, age, and tumor location. For patients with high grade gliomas after surgery and radiation, COX-2 was associated with shortened survival in univariate analysis (P=0.025). The COX-2, Cho/Cr value and age were the significant prognostic indicators shown in multivariate survival analysis. The COX-2 and Cho/Cr value of H-MRS have correlation, and are both positive indicators for overall survival of human high grade glioma, and could be combined as a joint role to provide more evidences to assess the biological behavior.

In situ click chemistry generation of cyclooxygenase-2 inhibitors

Cyclooxygenase-2 isozyme is a promising anti-inflammatory drug target, and overexpression of this enzyme is also associated with several cancers and neurodegenerative diseases. The amino-acid sequence and structural similarity between inducible cyclooxygenase-2 and housekeeping cyclooxygenase-1 isoforms present a significant challenge to design selective cyclooxygenase-2 inhibitors. Herein, we describe the use of the cyclooxygenase-2 active site as a reaction vessel for the in situ generation of its own highly specific inhibitors. Multi-component competitive-binding studies confirmed that the cyclooxygenase-2 isozyme can judiciously select most appropriate chemical building blocks from a pool of chemicals to build its own highly potent inhibitor. Herein, with the use of kinetic target-guided synthesis, also termed as in situ click chemistry, we describe the discovery of two highly potent and selective cyclooxygenase-2 isozyme inhibitors. The in vivo anti-inflammatory activity of these two novel small molecules is significantly higher than that of widely used selective cyclooxygenase-2 inhibitors.Traditional inflammation and pain relief drugs target both cyclooxygenase 1 and 2 (COX-1 and COX-2), causing severe side effects. Here, the authors use in situ click chemistry to develop COX-2 specific inhibitors with high in vivo anti-inflammatory activity.

In situ click chemistry generation of cyclooxygenase-2 inhibitors

Cyclooxygenase-2 isozyme is a promising anti-inflammatory drug target, and overexpression of this enzyme is also associated with several cancers and neurodegenerative diseases. The amino-acid sequence and structural similarity between inducible cyclooxygenase-2 and housekeeping cyclooxygenase-1 isoforms present a significant challenge to design selective cyclooxygenase-2 inhibitors. Herein, we describe the use of the cyclooxygenase-2 active site as a reaction vessel for the in situ generation of its own highly specific inhibitors. Multi-component competitive-binding studies confirmed that the cyclooxygenase-2 isozyme can judiciously select most appropriate chemical building blocks from a pool of chemicals to build its own highly potent inhibitor. Herein, with the use of kinetic target-guided synthesis, also termed as in situ click chemistry, we describe the discovery of two highly potent and selective cyclooxygenase-2 isozyme inhibitors. The in vivo anti-inflammatory activity of these two novel small molecules is significantly higher than that of widely used selective cyclooxygenase-2 inhibitors.

Traditional inflammation and pain relief drugs target both cyclooxygenase 1 and 2 (COX-1 and COX-2), causing severe side effects. Here, the authors use in situ click chemistry to develop COX-2 specific inhibitors with high in vivo anti-inflammatory activity.

The paradox role of caspase cascade in ionizing radiation therapy

Radiotherapy alone or in combination with chemotherapy/surgery is widely used for treatment of cancers. It reduces tumor growth and prevents metastasis. While ionizing radiation activates caspase cascade resulted in apoptosis in cancer cells, it also stimulates tumor cell re-population that leads to reduce the effectiveness of the radiation therapy. This review describes the mechanisms for paradox role of caspase cascade in cancer therapy and discusses the logical and practical strategies for improvement the therapeutic index of radiotherapy through enhancement of radiosensitivity and decreasing the rate of tumor recurrence.

Cyclooxygenase-2: A Role in Cancer Stem Cell Survival and Repopulation of Cancer Cells during Therapy

Cyclooxygenase-2 (COX-2) is an inducible form of the enzyme that catalyses the synthesis of prostanoids, including prostaglandin E2 (PGE₂), a major mediator of inflammation and angiogenesis. COX-2 is overexpressed in cancer cells and is associated with progressive tumour growth, as well as resistance of cancer cells to conventional chemotherapy and radiotherapy. These therapies are often delivered in multiple doses, which are spaced out to allow the recovery of normal tissues between treatments. However, surviving cancer cells also proliferate during treatment intervals, leading to repopulation of the tumour and limiting the effectiveness of the treatment. Tumour cell repopulation is a major cause of treatment failure. The central dogma is that conventional chemotherapy and radiotherapy selects resistant cancer cells that are able to reinitiate tumour growth. However, there is compelling evidence of an active proliferative response, driven by increased COX-2 expression and downstream PGE₂ release, which contribute to the repopulation of tumours and poor patient outcome. In this review, we will examine the evidence for a role of COX-2 in cancer stem cell biology and as a mediator of tumour repopulation that can be molecularly targeted to overcome resistance to therapy.

NSAIDs diclofenac, indomethacin, and meloxicam highly upregulate expression of ICAM-1 and COX-2 induced by X-irradiation in human endothelial cells

BACKGROUND

It is well known that radiation exposure to the heart and the use of non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of myocardial infarction (MI). Some NSAIDs are also known to act synergistically with ionizing radiation and have radio-sensitizing effects in radiotherapy. These evidences suggest that NSAIDs may affect the risk of MI after radiation exposure to the heart. In the present study, we investigated effects of NSAIDs on radiation-induced expression of cell adhesion molecules and COX-2, which are associated with inflammation and an increased risk of MI, in human endothelial cells.

METHODS

Effects of NSAIDs on radiation-induced expression of ICAM-1, VCAM-1, E-selectin, and COX-2 were investigated in human umbilical vein endothelial cells (HUVECs). As NSAIDs, diclofenac, etodolac, indomethacin, ketoprofen, meloxicam, and rofecoxib were used.

RESULTS

Irradiation with 10 Gy increased expression of ICAM-1 and COX-2, but it did not affect expression of VCAM-1 or E-selectin. All the NSAIDs upregulated radiation-induced expression of ICAM-1 and COX-2. The extent of upregulation varied depending on the types of NSAIDs. Indomethacin, diclofenac, and meloxicam highly upregulated radiation-induced expression of ICAM-1 and COX-2. The extent of upregulation was not related to the degree of COX-2 selectivity. An NF-κB inhibitor BAY 11-7082 suppressed radiation-induced expression of ICAM-1, but it did not suppress upregulated expression of ICAM-1 or COX-2 by combination treatment with X-irradiation and meloxicam, suggesting the existence of NF-κB-independent pathways for ICAM-1 and COX-2 induction.

CONCLUSION

Indomethacin, diclofenac, and meloxicam highly upregulated radiation-induced expression of ICAM-1 and COX-2 in HUVECs, which suggests that use of these NSAIDs may increase the effects of ionizing radiation and affect the risk of MI after radiation exposure to the heart.