Cyclooxygenase-2 up-regulates ataxia telangiectasia and Rad3 related through extracellular signal-regulated kinase activation

Marketed drugs used for the management of hypercholesterolemia as anticancer armament

The design of novel pharmacologic agents as well as their approval for sale in markets all over the world is a tedious and pricey process. Inevitably, oncologic patients commonly experience unwanted effects of new anticancer drugs, while the acquisition of clinical experience for these drugs is largely based on doctor–patient partnership which is not always effective. The repositioning of marketed non-antineoplastic drugs that hopefully exhibit anticancer properties into the field of oncology is a challenging option that gains ground and attracts preclinical and clinical research in an effort to override all these hindrances and minimize the risk for reduced efficacy and/or personalized toxicity. This review aims to present the anticancer properties of drugs used for the management of hypercholesterolemia. A global view of the antitumorigenicity of all marketed antihypercholesterolemic drugs is of major importance, given that atherosclerosis, which is etiologically linked to hypercholesterolemia, is a leading worldwide cause of morbidity and mortality, while hypercholesterolemia and tumorigenesis are known to be interrelated. In vitro, in vivo and clinical literature data accumulated so far outline the mechanistic basis of the antitumor function of these agents and how they could find application at the clinical setting.

COX-2 inhibitor NS-398 suppresses doxorubicin-induced p53 accumulation through inhibition of ROS-mediated Jnk activation

Cyclooxygenase-2 (COX-2) is one of the isoforms of cyclooxygenase, a rate-limiting enzyme in the arachidonic acid cascade. COX-2 protein expression is highly induced by numerous factors and it has been reportedly overexpressed in various human malignancies. Although anti-tumorigenic effects of COX-2 inhibitors have been shown, several lines of evidence suggest that COX-2 inhibitors antagonize the cytotoxicity of chemotherapeutic agents. In this study, we investigated the effect of NS-398, a COX-2 inhibitor, on modulation of doxorubicin (DOX)-induced p53 accumulation. Non-selective and selective COX-2 inhibitors attenuated DOX-induced accumulation of wild type (WT) but not mutant p53. Nutlin-3α or MG132 abolished the suppressive effect of a COX-2 inhibitor on DOX-induced p53 increase. Moreover, the DOX-induced increase in p53 protein levels was reduced in COX-2 knockout (KO) mouse embryonic fibroblasts (MEFs) compared to those in WT or COX-1 KO MEFs. DOX-induced accumulation of p53 was attenuated by a specific inhibitor or knockdown of Jun-N-terminal kinase (Jnk). In addition, DOX-induced Jnk activation was decreased in COX-2 KO MEFs or by COX-2 inhibition, suggesting that Jnk stabilizes p53 by a mechanism that involves COX-2. Pre-treatment with a reactive oxygen species (ROS) scavenger, N-acetylcysteine, attenuated DOX-induced Jnk activation and subsequent p53 accumulation. Furthermore, the absence or inhibition of COX-2 resulted in suppression of DOX-induced increase in ROS levels. These results suggest that COX-2 activates Jnk through modulation of ROS levels, leading to accumulation of p53. Our study identifies a putative novel cross-talk between COX-2 and p53. © 2016 Wiley Periodicals, Inc.

Expression of COX-2 on Reed-Sternberg cells is an independent unfavorable prognostic factor in Hodgkin lymphoma treated with ABVD

Cyclooxygenase 2 (COX-2) is an inflammatory enzyme involved in the pathogenesis and prognosis of several malignancies. In the present study, we investigated the prognostic value of COX-2 expression in a large (N = 242), uniformly treated Hodgkin lymphoma (HL) population from the Spanish Network of HL using tissue microarrays. Univariate and multivariate analysis was done, including comparing the most recognized clinical variables: the early- and advanced-stage subgroups. COX-2 was expressed on Reed-Sternberg cells in 37% of patients. There were no differences in the distribution of clinical variables according to COX-2 expression. With a median follow-up time of 58 months, PFS at 5 years was 60% and 79% for COX-2+ and COX-2− patients, respectively (P = .003). The overall survival was 73% and 91%, respectively (P < .001). The major impact on prognosis was observed in the early AA stage (I-II) group. In fact, in these low-risk groups the expression of COX-2 defined a group with significantly worse progression-free and overall survival. In conclusion, COX-2 was expressed on Reed-Sternberg cells in one-third of HL patients and was a major independent, unfavorable prognostic factor in early-stage HL. We conclude that COX-2 may be a major prognostic variable in HL and a potential therapeutic target.

Cooperative enhancement of radiosensitivity after combined treatment of 17-(allylamino)-17-demethoxygeldanamycin and celecoxib in human lung and colon cancer cell lines

We investigated whether the combined treatment of 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), an inhibitor of heat-shock protein 90 (hsp90), and celecoxib, an inhibitor of cyclooxygenase-2, can cooperatively enhance the radiosensitivity of various human cancer cells. Combined treatment with 17-AAG and celecoxib, at clinically relevant concentrations, cooperatively induced radiosensitization in all tested cancer cells, but not in normal cells. Cooperative radiosensitization by the drug combination was also shown in a human tumor xenograft system. We found that ataxia-telangiectasia and rad3-related (ATR) and ataxia-telangiectasia mutated (ATM) are novel client proteins of hsp90. Combined treatment with 17-AAG and celecoxib cooperatively induced downregulation of ATR and ATM. In conclusion, combined treatment with 17-AAG and celecoxib at clinically relevant concentrations may significantly enhance the therapeutic efficacy of ionizing radiation.

ERK pathway activation is required for amyloid-β(1-40)(-)induced neurotoxicity of THP-1 human monocytes towards SK-N-SH neuroblastoma

Alzheimer's disease (AD) is characterized by amyloid-β peptide deposition, increased activated microglia, and progressive loss of neurons in the brain. Although Aβ₁₋₄₀ can elicit inflammation in microglia, the intracellular signaling events mediating these effects are poorly defined. Here we show that cell-free supernatant from Aβ₁₋₄₀-treated THP-1 monocytes induced cytotoxicity towards neuroblastoma SK-N-SH cells. Exposure of THP-1 monocytes to Aβ₁₋₄₀ leads to increased tyrosine phosphorylation and extracellular signaling-regulated kinase (ERK) and increased levels of inflammatory cytokines (IL-1β, IL-8, and TNF-α) in the supernatant of THP-1 monocytes. Pretreatment of THP-1 monocytes with either a protein tyrosine kinase (PTK) inhibitor or an ERK inhibitor protects SK-N-SH cells from the cytotoxic effect of conditional supernatant from Aβ₁₋₄₀-treated THP-1 monocytes. Aβ₁₋₄₀-treated THP-1 monocytes also lead to upregulation of cyclooxygenase-2 and iNOS expression and increased of nitric oxide production. These results suggest that Aβ₁₋₄₀-induced activation of PTK/MEK/ERK pathway in THP-1 monocytes leads to the release of inflammatory factors that are toxic to SK-N-SH cells and might contribute to the onset of AD.

Systematic analyses of genes associated with radiosensitizing effect by celecoxib, a specific cyclooxygenase-2 inhibitor

To investigate genes regulated by COX-2 or a COX-2 specific inhibitor, celecoxib, in irradiated cancer cells, we analyzed changes in gene expression using complementary DNA microarray following celecoxib or combined celecoxib and ionizing radiation (IR) treatment in a stable COX-2 knockdown A549 (AS) and a mock cell line (AN). Thirty-six genes were differentially expressed by COX-2 knockdown. Celecoxib changed the expressions of 40 and 69 genes in AN and AS cells, respectively. Twenty-seven genes were synchronously regulated by COX-2 and celecoxib. Among these, celecoxib regulated ras homolog gene family B and mitosin protein expression in a COX-2 dependent manner, especially in irradiated cells. In addition, we identified 11 genes that changed by more than 1.5 times the expected additive values after celecoxib and IR treatment. The current study may provide evidence that COX-2 or celecoxib regulates various intracellular functions in addition to their enzymatic activity regulation. We also identified candidate molecules that may be responsible for COX-2-dependent radiosensitization by celecoxib.

Gefitinib radiosensitizes non-small cell lung cancer cells through inhibition of ataxia telangiectasia mutated

Purpose

Inhibitors of epidermal growth factor receptor (EGFR) have shown dramatic results in a subset of patients with non-small cell lung cancer (NSCLC), and have also been shown to enhance the effect of ionizing radiation (IR). We investigated how gefitinib, an orally given EGFR inhibitor for NSCLC patients, can radiosensitize NSCLC cells.

Experimental Design and Results

In clonogenic survival assays performed in three NSCLC cell lines, gefitinib radiosensitized NCI-H460 and VMRC-LCD but not A549 cells. Gefitinib pretreatment induced multinucleated cells after IR exposure in NCI-H460 and VMRC-LCD, but not in A549 cells. Gefitinib also inhibited activation of ataxia telangiectasia mutated (ATM) after IR-exposure in NCI-H460 and VMRC-LCD, but not in A549 cells. An ATM specific inhibitor increased IR-induced multinucleated cells in both NCI-H460 and A549 cells. Gefitinib pretreatment inhibited the gradual decrease of γH2AX foci relative to time after IR exposure in NCI-H460 but not in A549 cells. Suppression of COX-2 in A549 cells induced multinucleated cells and caused radiosensitization after gefitinib+IR treatment. In contrast, COX-2 overexpression in NCI-H460 cells attenuated the induction of multinucleation and radiosensitization after the same treatment.

Conclusions

Our results suggest that gefitinib radiosensitizes NSCLC cells by inhibiting ATM activity and therefore inducing mitotic cell death, and that COX-2 overexpression in NSCLC cells inhibits this action of gefitinib.