COXIBs and 2,5-dimethylcelecoxib counteract the hyperactivated Wnt/β-catenin pathway and COX-2/PGE2/EP4 signaling in glioblastoma cells

Abstract

Background Glioblastoma (GBM) is the deadliest and the most common primary brain tumor in adults. The invasiveness and proliferation of GBM cells can be decreased through the inhibition of Wnt/β-catenin pathway. In this regard, celecoxib is a promising agent, but other COXIBs and 2,5-dimethylcelecoxib (2,5-DMC) await elucidation. Thus, the aim of this study was to analyze the impact of celecoxib, 2,5-DMC, etori-, rofe-, and valdecoxib on GBM cell viability and the activity of Wnt/β-catenin pathway. In addition, the combination of the compounds with temozolomide (TMZ) was also evaluated. Cell cycle distribution and apoptosis, MGMT methylation level, COX-2 and PGE2 EP4 protein levels were also determined in order to better understand the molecular mechanisms exerted by these compounds and to find out which of them can serve best in GBM therapy. Methods Celecoxib, 2,5-DMC, etori-, rofe- and valdecoxib were evaluated using three commercially available and two patient-derived GBM cell lines. Cell viability was analyzed using MTT assay, whereas alterations in MGMT methylation level were determined using MS-HRM method. The impact of COXIBs, in the presence and absence of TMZ, on Wnt pathway was measured on the basis of the expression of β-catenin target genes. Cell cycle distribution and apoptosis analysis were performed using flow cytometry. COX-2 and PGE2 EP4 receptor expression were evaluated using Western blot analysis. Results Wnt/β-catenin pathway was attenuated by COXIBs and 2,5-DMC irrespective of the COX-2 expression profile of the treated cells, their MGMT methylation status, or radio/chemoresistance. Celecoxib and 2,5-DMC were the most cytotoxic. Cell cycle distribution was altered, and apoptosis was induced after the treatment with celecoxib, 2,5-DMC, etori- and valdecoxib in T98G cell line. COXIBs and 2,5-DMC did not influence MGMT methylation status, but inhibited COX-2/PGE2/EP4 pathway. Conclusions Not only celecoxib, but also 2,5-DMC, etori-, rofe- and valdecoxib should be further investigated as potential good anti-GBM therapeutics.

Up-Regulation of Cyclooxygenase-2 (COX-2) Expression by Temozolomide (TMZ) in Human Glioblastoma (GBM) Cell Lines

“…Our findings also show that NS398 was able to overcome TMZ-induced overexpression of β-catenin, MGMT, and SOX-2 in T98G, thus confirming the key and the hierarchically superior role played by the COX-2/PGE2 system in the cascade of pathways activated by TMZ and implicated in chemoresistance. NS398 has been one of the earliest COX-2-selective inhibitors discovered [54] and, even if not yet approved by the FDA for clinical use, it continues to be largely used, also recently, by a plethora of researchers, as a prototype COX-2 inhibitor for in vitro and in vivo studies on several types of cancers, including GBM [20,36,55,56]. For our group, in particular, the present work represents a continuation of previous studies showing the ability of NS398 to influence the biology of GBM cell lines as well as the relative derived-neurospheres [13].…”

Attenuation of Pancreatic Cancer In Vitro and In Vivo via Modulation of Nrf2 and NF-κB Signaling Pathways by Natural Compounds

“…Moreover, this observation is in agreement with the results of our previous studies [ 17 , 21 ]. Among the pro-inflammatory enzymes, COX-2 is one of the most important regulators of angiogenesis, inflammation, and carcinogenesis [ 47 , 48 ]. The results of our current study suggest that decreased transcript and protein levels of COX-2 in PSN-1 cells are responsible for the anti-inflammatory properties of these compounds/phytochemicals.…”

Lichen Secondary Metabolites Inhibit the Wnt/β-Catenin Pathway in Glioblastoma Cells and Improve the Anticancer Effects of Temozolomide

“…The A-172 and U-138 MG cell lines were purchased from the American Type Culture Collection (ATCC), whereas the T98G cell line was obtained from the European Collection of Authenticated Cell Cultures (ECACC). It has been confirmed by us that O 6 -methylguanine-DNA methyltransferase ( MGMT ), the key factor determining the response to alkylating agents, such as TMZ, is expressed in T98G and U-138 MG cells, whereas in A-172 the expression of MGMT is silenced by promoter methylation [ 19 ]. Therefore, the cell lines differ in terms of TMZ sensitivity; A-172 is regarded as TMZ sensitive, whereas T98G and U-138 MG are TMZ resistant.…”