The Study On The Mechanism Of The Antitumor Effect And Reversal Of Cisplatin Resistance Of Platinum(Ⅳ) Prodrugs Containing Wogonin

Although platinum(Ⅱ)-based chemotherapeutics,especially cisplatin,are the first line treatments for various types of malignancies,serious side effects and drug resistance became major limitations of cisplatin-based chemotherapeutics.Among them,drug resistance is widely recognized as an important cause of clinical chemotherapy failure.Hence,it is essential to develop a safer and more effective platinum drug and explore the molecular mechanism of overcoming cisplatin-induced resistance to improve the success rate of chemotherapy in patients.Platinum(Ⅳ)complexes(preferred to be prodrugs of cisplatin)are becoming the most promising alternatives to the limitations imposed by traditional platinum(Ⅱ)drugs due to their greater kinetic inertness than platinum(Ⅱ)drugs.Wogonin is widely studied for its anti-inflammatory activity and potential anti-tumor activity.Ⅰn addition,the platinum(Ⅱ)complex,DN604,developed by our group has recently been found to own significant antitumor activity and low toxicity.Based on that,our group synthesized two platinum(Ⅳ)prodrugs based on the wogonin,named complex Ⅰ(Cis-wog)and target complex Ⅱ(DN604-wog),by addition of the wogonin fragment to the axial position of cisplatin and DN604 through a linker group.Ⅰn this study,a series of bioactivity studies on the two platinum(Ⅳ)complexes synthesized in vitro will be conducted to explore their anti-tumor effects and their mechanisms of reversing cisplatin-induced resistance.For complex Ⅰ(Cis-wog),cytotoxic activity studies in vitro showed that it had excellent cytotoxicity against human non-small cell lung cancer cells A549 and cisplatin-resistant A549/cDDP cells.Especially for A549/cDDP cells,Cis-wog showed significantly better cytotoxicity than cisplatin.Further research found that Cis-wog was firstly reduced to the parent platinum(Ⅱ)complex,and then interacted with DNA to induce apoptosis and the cell cycle arrest mainly in the S phase.Mechanistic studies showed that Cis-wog was able to induce DNA damage to the greatest extent in both A549 and A549/cDDP cells,which was mainly due to more severe DNA single-strand breaks.Ⅰn addition,the results also showed that the potent antitumor activity of Cis-wog against cisplatin-resistant A549/cDDP cells was not only due to the increase of platinum uptake by cancer cells but also for its inhibition of JWA.That is,inhibition of DNA single-strand damage repair mediated by JWA in A549/cDDP cells could overcome cisplatin-induced resistance and trigger apoptosis.For complex Ⅱ(DN604-wog),cytotoxic activity studies in vitro showed that DN604-wog had closed cytotoxicity to cisplatin in human gastric cancer SGC-7901 cells,but it had superior cytotoxicity to cisplatin,DN604 and wogonin in cisplatin-resistant SGC-7901/cDDP cells.Ⅰt also had lower toxicity to human normal cells(HUVEC).Moreover,it retained the anti-oxidant and anti-inflammatory activities of wogonin.Further mechanistic studies indicated that DN604-wog could cause ROS accumulation in cells,decrease mitochondrial membrane potential(ΔΨm),and then induce cell apoptosis.The results from western blot showed that DN604-wog could reverse cisplatin-induced resistance by inhibiting NF-κB activation in SGC-7901/cDDP cells to promote apoptosis.CK2 enzyme inhibitory activity assay showed that DN604-wog blocked CK2-mediated NF-κB signaling pathway by inhibiting CK2 activity,thereby reversing cancer cell resistance to cisplatin.