Catch and Release Photosensitizers: Combining Dual-Action Ruthenium Complexes with Protease Inactivation for Targeting Invasive Cancers

Abstract

Dual action agents containing a cysteine protease inhibitor and Rubased photosensitizer for photodynamic therapy (PDT) were designed, synthesized, and validated in 2D culture and 3D functional imaging assays of triple-negative human breast cancer (TNBC). These combination agents deliver and release Rubased PDT agents to tumor cells and cause cancer cell death upon irradiation with visible light, while at the same time inactivating cathespin B (CTSB), a cysteine protease strongly associated with invasive and metastatic behavior. In total five Rubased complexes were synthesized with the formula [Ru(bpy)2(l)](O2CCF3)2 (3), where bpy = 2,2′-bipyridine and 1 = a bipyridine-based epoxysuccinyl inhibitor; [Ru(tpy)(NN)(2)](PF6)2, where tpy = terpiridine, 2 = a pyridine-based epoxysuccinyl inhibitor and NN = 2,2′-bipyridine (4); 6,6′-dimethyl-2,2′-bipyridine (5); benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine (6); and 3,6-dimethylbenzo[i]-dipyrido[3,2-a:2′,3′ -c]phenazine (7). Compound 3 contains a [Ru(bpy)3]2+ fluorophore and was designed to track the subcellular localization of the conjugates, whereas compounds 4–7 were designed to undergo either photoactivated ligand dissociation and/or singlet oxygen generation. Photochemical studies confirmed that complexes 5 and 7 undergo photoactivated ligand dissociation, whereas 6 and 7 generate singlet oxygen. Inhibitors 1–7 all potently and irreversibly inhibit CTSB. Compounds 4–7 were evaluated against MDA-MB-231 TNBC and MCF-10A breast epithelial cells in 2D and 3D culture for effects on proteolysis and cell viability under dark and light conditions. Collectively, these data reveal that 4–7 potently inhibit dye-quenched (DQ) collagen degradation, whereas only compound 7 causes efficient cell death under light conditions, consistent with its ability to release a Ru(II)-based photosensitizer and to also generate 1O2.

A dinuclear ruthenium(ii) phototherapeutic that targets duplex and quadruplex DNA

“…[4][5][6][7][8] and Ru II complexes have attracted particular attention as sensitizers. [9][10][11][12][13][14][15][16][17][18] For similar reasons, this class of compounds has also been investigated as probes for optical microscopy. A case in point is the probe described in previous reports by the Thomas group.…”

A self-assembled Ru–Pt metallacage as a lysosome-targeting photosensitizer for 2-photon photodynamic therapy

“…Singlet oxygen ( 1 O 2 ) is the major ROS generated by Ru(II)based PSs (7,(55)(56)(57) whereas metallacage 5 displayed poor cellular uptake due to its limited solubility in aqueous solution (SI Appendix, Fig. S12).…”

“…Herein, we describe the use of coordinationdriven self-assembly for the preparation of a Ru-Pt bimetallic metallacage as a PS for 2-photon PDT. Ru(II) complexes have attracted much attention as PS for PDT due to their rich photochemical and photophysical properties (7,(55)(56)(57). Combining 6 Ru(II)-based PSs and 4 Pt(II)-based acceptor building blocks in a single supramolecular ensemble, the octahedral Ru-Pt metallacage was synthesized using coordination-driven self-assembly and displays deep-red emission, a large 2-photon absorption crosssection, and high ROS generation efficiency upon activation by 2photon light irradiation.…”

Photoactivatable Protherapeutic Nanomedicine for Cancer

“…[ 26 ] Various PPGs including o ‐nitrobenzyl and derivatives, coumarin, pyrenylene, ruthenium (II) complex, etc., have been designed and developed as phototriggers with variable chemical reactivity and photonsensitivity ( Table 1 ). [ 27 ] Therapeutics, such as small‐molecular anticancer drugs (e.g., chlorambucil, coumarin, 5‐FU, camptothecin, DOX), [ 1a,28 ] small interfering RNA (siRNA), [ 29 ] enzymes, [ 30 ] gene [ 31 ] etc. have been caged and photo released at the site of interests by nanoagents including micelles, [ 32 ] magnetic nanoparticles, [ 33 ] gold nanoparticles, [ 34 ] UCNPs [2 8b,30 ] etc.…”