Anticancer potential of organometallic ruthenium complexes

Kompleksi na bazi platine dominiraju u kemoterapiji zadnjih nekoliko desetljeća. Međutim, zbog visoke opće toksičnosti i razvoja otpornosti tumora na lijek, javlja se potreba za sintezom novih spojeva sa smanjenim popratnim pojavama. U tu svrhu, istražuju se različiti organometalni kompleksi, među kojima su se svojom antitumorskom aktivnošću istaknuli kompleksi rutenija. U ovom istraživanju istražene su biološke karakteristike novosintetiziranih kompleksa rutenija 1 i 2, s fosfanskim ligandima supstituiranim kiralnim ili akiralnim esterima aminokiselina. Citotoksičnost sintetiziranih spojeva ispitana je 3-(4,5-metiltiazol-2-il)-2,5-difeniltetrazolium bromid testom na ljudskim stanicama karcinoma vrata maternice (HeLa). Četiri (2pG, 2pA, 2mG i 2mA) od šest sintetiziranih bikonjugata pokazalo je značajnu toksičnost, usporedivu sa cisplatinom. Na temelju uočenih karakteristika biološkog djelovanja na stanice HeLa izdvojen je kompleks 2mG čija je citotoksičnost dalje ispitivana na nekoliko tumorskih i normalnih staničnih linija. Veća toksičnost prema tumorskim, u odnosu na normalne stanične linije, ukazuje na selektivnu aktivnost spoja. Protočnom citometrijom utvrđeno je da spoj 2mG zaustavlja stanice u G1/S fazi staničnog ciklusa i uzrokuje povećanje SubG1 populacije stanica, što upućuje na smrt stanica apoptozom. Predtretman HeLa stanica sa specifičnim inhibitorom sinteze, butionin sulfoksiminom i specifičnim prekursorom sinteze glutationa, N-acetil cisteinom, te specifičnim inhibitorom glutation-S-transferaze, etakrinom kiselinom i specifičnim inhibitorom membranskih trasportera MRP1/2, probenecidom, ukazao je na važnu ulogu glutationa u odgovoru i detoksikaciji stanica nakon tretmana sa sintetiziranim organometalnim kompleksima rutenija.Platinum-based drugs have been predominantly used in chemotherapy for decades. However, due to their high general toxicity and development of tumour drug resistance, there is a constant need to synthesize new compounds with reduced side effects. Organometallic ruthenium complexes have already shown promising anticancer activity. In this research, we explored biological characteristics of newly synthesized (p-cymene)-ruthenium complexes 1 and 2, bearing phoshane ligands substituted with chiral or non-chiral amino acid esters. Cytotoxic activity was investigated on human cervix carcinoma cell line (HeLa) using MTT assay. Four (2pG, 2pA, 2mG and 2mA) out of six synthesized metallated biconjugates showed significant toxicity. Based on characteristics of biological effect on HeLa cells 2mG compound was selected for further experiments. The higher level of toxicity towards tumour compared to normal cell lines indicated its selective activity. Further, using flow cytometry and propidium iodide staining, it was detected that 2mG arrests cells in G1/S phase of cell cycle and causes dose-dependent increase of SubG1 cell population, suggesting its ability to induce apoptosis. Effects of pretreatment with specific inhibitor of glutathione synthesis, buthionine sulfoximine, or specific precursor N-acetyl-cysteine, and inhibitor of glutathion-S-transferase, ethacrynic acid, or inhibitor of multidrug resistance protein family MRP1/2, probenecid, on survival of HeLa cells indicated that glutathion plays important role in cell response and detoxification of newly synthesized organometallic ruthenium compounds