Study Of Antitumor Platinum(Ⅳ) Prodrugs Containing Small Molecule Kinase Inbibitor

In this working, a serious of novel Pt(IV) prodrugs were designed and prepared by a fusion of platinum(IV) and CX-4945(Silmitasertib) that is a potent ATP-competitive CK2 inhibitor. The platinum complexes were characterized by 1H NMR, 13C NMR and high resolution electrospray ionization mass spectroscopy (ESI-MS).In order to a further study of those Pt(IV) prodrugs, a serious of chemical and biological experiments was carried out to Cx-platin, a representative compounds was carried out to explore its’ antitumor porperties and related mechanism. The main contents included were blow.The HPLC chromatograms shows that Cx-platin is able to release both CX-4945 and cisplatin under reduction of ascorbic acid. And it was observed that Cx-platin kept unchangeable in a period of 24 hours, indicating that the designed compound is stable under the normal condition.The ICso values of Cx-platin following 72 hours treatments with selective cancer cell lines were apparently lower than those of cisplatin alone, which showed 2 to 3 folds increased cytotoxicity in CK2 over-expressed cancer cells and Cx-platin was sensitive to cisplatin-induced resistance cancer cell. The analysis of cellular uptake illustrated that the amounts of Cx-platin in cancer cells was dramatically higher than that of cisplatin, reached 3-4 folds in SGC-7901 and SGC-7901/cDDP cells. Because of the high uptake of Pt amounts, Cx-platin could induce apoptosis much more effectively than cisplatin.Results from the CK2 kinase assay indicated that Cx-platin can suppress CK2 activity as strongly as CX-4945. Comet assay shows that Cx-platin produced dramatically prominent tails induced by DNA strand breaks.Western blot analysis demonstrated that Cx-platin increased phosphorylation of CHK1 and CHK2, meanwhile Cx-platin reduced the expression level of CHK1 and CHK2. The data showed that Cx-platin could suppress the ability of cancer cells to repair DNA strand breaks and induce DNA double-strand breaks.Immunofluorescence and microscopy data illustrated that treatment of cancer cells with Cx-platin, it produced increased level of discrete yH2AX foci and led to a great suppression of the phosphorylation of XRCC1 and MDC1, proving that the extent of DNA single strand breaks and double strand breaks increased in cancer cells and the DNA damage repair is inhibitated. While treatment with cisplatin alone could only induce DNA single strand breaks and DNA damage repair was normal.In vivo antitumor efficacy data shown that that Cx-platin exhibited significantly the highest tumor growth inhibition among the tested samples, meanwhile effected with less dosage times of three times a period. The the body weights test and immunohistochemistry analysis demonstrated that Cx-platin had hardly toxic effect on normal tissues.Upon above all the study, Cx-platin possessing significant antitumor activity with nearly no toxic effect. It has a unique abilitiy to overcome drug resistance. And Cx-platin could effectively induce DNA damage including DNA single strand breaks and DNA double strand breaks via suppressing DNA damage repair.