Exploring Nitric Oxide (NO)-Releasing Celecoxib Derivatives as Modulators of Radioresponse in Pheochromocytoma Cells

Abstract

COX-2 can be considered as a clinically relevant molecular target for adjuvant, in particular radiosensitizing treatments. In this regard, using selective COX-2 inhibitors, e.g., in combination with radiotherapy or endoradiotherapy, represents an interesting treatment option. Based on our own findings that nitric oxide (NO)-releasing and celecoxib-derived COX-2 inhibitors (COXIBs) showed promising radiosensitizing effects in vitro, we herein present the development of a series of eight novel NO-COXIBs differing in the peripheral substitution pattern and their chemical and in vitro characterization. COX-1 and COX-2 inhibition potency was found to be comparable to the lead NO-COXIBs, and NO-releasing properties were demonstrated to be mainly influenced by the substituent in 4-position of the pyrazole (Cl vs. H). Introduction of the N-propionamide at the sulfamoyl residue as a potential prodrug strategy lowered lipophilicity markedly and abolished COX inhibition while NO-releasing properties were not markedly influenced. NO-COXIBs were tested in vitro for a combination with single-dose external X-ray irradiation as well as [177Lu]LuCl3 treatment in HIF2α-positive mouse pheochromocytoma (MPC-HIF2a) tumor spheroids. When applied directly before X-ray irradiation or 177Lu treatment, NO-COXIBs showed radioprotective effects, as did celecoxib, which was used as a control. Radiosensitizing effects were observed when applied shortly after X-ray irradiation. Overall, the NO-COXIBs were found to be more radioprotective compared with celecoxib, which does not warrant further preclinical studies with the NO-COXIBs for the treatment of pheochromocytoma. However, evaluation as radioprotective agents for healthy tissues could be considered for the NO-COXIBs developed here, especially when used directly before irradiation.

Solid-Phase Parallel Synthesis of Dual Histone Deacetylase-Cyclooxygenase Inhibitors

“…As lead compounds of this study, indometacin happens to be unselective, whereas celecoxib represents a selective inhibitor for the isoenzyme. The ability to inhibit both isoforms, ovine COX-1 and human COX-2, was determined using the “COX Fluorescent Inhibitor Screening Assay Kit” (Cayman Chemical, Ann Arbor, MI, USA) in a concentration range up to 100 µM [ 40 , 41 ]; the results are shown in Table 2 . In general, modification of indometacin ( A ) and celecoxib derivatives ( B and C ) with linker and zinc binding motifs was tolerated by COX-2 leading to inhibitory potencies in the low micromolar range of IC 50 between 1–10 µM with exception of compound B1 (IC 50 = 43.0 µM).…”

“…Commercially available chemicals were purchased from abcr GmbH (Karlsruhe, Germany), Acros Organics (Thermo Fisher Scientific, Geel, Belgium), Alfa Aesar (Thermo Fisher Scientific, Kandel, Germany), Carbolution Chemicals GmbH (St. Ingbert, Germany), Carl Roth GmbH + Co. KG (Karlsruhe, Germany), Fluorochem (Hadfield, United Kingdom), Grüssing (Filsum, Germany), Iris Biotech GmbH (Marktredwitz, Germany), Merck KGaA (Darmstadt, Germany), Sigma-Aldrich (St. Louis, MO, USA), TCI Deutschland GmbH (Eschborn, Germany), and VWR International (Radnor, PA, USA) and used without further purification. The cap groups 1-(4-sulfamoylphenyl)-5-( p -tolyl)-1 H -pyrazole-3-carboxylic acid and 1-(4-(methylsulfonyl)phenyl)-5-( p -tolyl)-1 H -pyrazole-3-carboxylic acid were prepared as previously reported [ 41 , 48 ]. Methyl 3-fluoro-4-methylbenzoate and methyl 4-(bromomethyl)-3-fluorobenzoate, for the synthesis of the fluorobenzyl linker, were synthesized according to the literature [ 45 ].…”

“…The log D 7.4HPLC value was determined as previously reported by us [ 41 ] utilizing a modified HPLC method originally described by Donovan and Pescatore [ 46 ]. Hydrocortisone (t R = 10.70 min, log D 7.4 = 1,46) and triphenylene (t R = 29.50 min, log D 7.4 = 5.49) served as references to calculate log D 7.4HPLC as given in formula 4 of reference [ 46 ] and toluene (t R = 16.51 min, measured log D 7.4HPLC = 2.71, literature log D 7.4 = 2.72) as internal reference.…”

“…The COX inhibition potency against ovine COX-1 and human COX-2 was determined using the fluorescence-based COX assay “COX Fluorescent Inhibitor Screening Assay Kit” (catalog number 700100; Cayman Chemical, Ann Arbor, MI, USA) according to the manufacturer’s instructions as previously reported by us [ 40 , 41 ]. All compounds were assayed in a concentration range of 10 nM to 100 μM in a 10-fold dilutions series, and every inhibitor concentration was assayed in duplicate.…”

Improving susceptibility of neuroendocrine tumors to radionuclide therapies: personalized approaches towards complementary treatments

“…Additionally, the role of COX-2 in CSC survival and recolonization after therapy has been considered in detail elsewhere, making it clear that inhibiting COX-2 is an effective way to prevent treatment failure due to tumor repopulation [161]. Addressing COX-2 by selective inhibitors or dual drugs as an adjuvant approach is also feasible in NENs [162][163][164][165].…”