Design, Synthesis And Apoptosis-inducing Activities And Mechanism Of Ruthenium (Ⅱ) Polypyridyl Complexes

With the development of molecular biology research, the pathogenesis of tumor wasrecognized gradually from past single factor up to multiple factor. It would create a new wayfor antitumor drugs research by investigating the relationship between tumor cells and drug. Alarge number of experiments reported the potential bioactive ligands of benzimidazolyl pyridinederivatives and phenylterpyridine derivatives which were acted as synthesized ligands in thepaper. Two series of synthesized ruthenium complexes were screened and studied aboutapoptosis-inducing activities and mechanism, which indicated that the ruthenium complex with-NO2substituent ligand revealing the highest antitumor activity would displayed as the potentialantitumor drug. The main results were as follows:Two series ruthenium complexes with phenylterpyridine derivatives and2,6-bis(benzimidazolyl) pyridine derivatives have been synthesized, characterized by ICP-AESanalysis, mass spectrometry (ESI-MS) and nuclear magnetic (1HNMR), which indicatedsynthesized complexes were target products.The in vitro anticancer activities of ruthenium complexes was screened against severalhuman tumor cell lines and a normal cell line and by MTT assay, which suggested rutheniumcomplexes displayed obvious effect inhibition to antitumor cells and low side effects. Theantitumor activity was affected by the ligand importing substituent group, especially,-NO2substituent ligand. The ruthenium complex with nitro-phenylterpyridine and phenanthrolinedisplayed the highest toxicity with IC50value at16.9μM in A375cells and IC50value ofruthenium complex with nitro-benzimidazolyl pyridine is at5.9μM in Nerua-2a cells. Greenfluorescence was not detected in cell nucleus but cytoplasm because synthesized complexesfluoresce under uv irradiation, which indicated complex played a part in cell cytoplasm.The part of cellular uptake and transferrin revealed that ruthenium complex wastransported to cytoplasm by transferrin receptor. The tested complex induced apoptosis throughSub-G1increasing in tumor cells by flow cytometry and TUNEL technology. It was said thatdeath receptor was the main pathway induced apoptosis because Caspase-8activity improvedup150%but20%was up in Caspase-9activity. Western blotting analysis revealed that thetested complex treatments significantly suppressed the expression of pro-survival Bcl-2family proteins, Such as Bcl-2, caspase-9, and moderately upregulated the expression levels ofpro-apoptosis Bcl-2family proteins. The experiment of interacting with DNA suggestedcomplex inserted DNA combining way. The tested complex-induced A375cell induction ofDNA damage was investigated by Comet assay. Western blotting analysis revealed that thetested complex treatments was up regulation of phosphorylation histone protein, whichprompted that tested complex-induced cells apoptosis acted as a common mechanism toactivate the DNA damage response. phosphorylated AKT and ERK protein were downregulated in cells treatment with tested drug in a dose-dependent manner. Meanwhile, thekinase of p38and JNK showed dose-dependent significant increase in treated cells. Based onthese results, which implied that AKT and MAPK signaling pathways were implicated intreated cancer cells induced apoptosis.From what had been discussed above, synthesized complexes were the target products.Screening antitumor activity revealed structure-activity relationships among the synthesizedruthenium complex, which displayed a guiding role for designing antitumor drugs. Themechanism investigation of synthesized ruthenium complexes would guide development fortargeted drugs.