Molecular Mechanism Of Onvansertib And THZ2 Inhibiting Lung Adenocarcinoma And Reversing Cisplatin Resistance

As one of the most common tumors in the world,lung cancer also presents the highest morbidity and mortality among male malignant tumors in China.In pathology,lung cancer types can be divided into non-small cell lung cancer(NSCLC)and small cell lung cancer(SCLC)and non-small cell lung cancer is the main type,accounting for about 80%.Non-small cell lung cancer can be classified as lung adenocarcinoma(LUAD),lung squamous cell carcinoma(LUSC),and large cell carcinoma.In recent years,the incidence of lung adenocarcinoma has been on the rise.Although treatment methods have been increasing,the therapeutic effect is still not ideal,and the 5-year survival rate is only 15%.At present,early detection,diagnosis and treatment are the key to the prevention and treatment of lung adenocarcinoma.Because the early clinical manifestations of lung adenocarcinoma are not obvious and drug resistance easily occurs in therapy.The screening and diagnosis of lung adenocarcinoma have become the focus of lung cancer research.Polo-like kinases are widely found in serine/threonine kinases in eukaryotic cells,including Polo-like kinase1,Polo-like kinase 2,Polo-like kinase 3,Polo-like kinase 4 and Polo-like kinase 5,which play an important role in DNA replication and mitosis.PLK1 is abnormally expressed in many tumors,including breast cancer,nasopharyngeal carcinoma,glioblastoma,non-Hodgkin’s lymphoma,leukemia,melanoma,etc.,which is closely related to the prognosis of tumor patients,and it is also the most studied and most representative kinase.Currently,more and more inhibitors have been designed to target PLK1,but the therapeutic efficacy of these inhibitors needs to be evaluated in vitro and in vivo.The therapeutic effect of Onvansertib as a novel and highly effective second generation PLK1 kinase inhibitor in lung adenocarcinoma remains unclear.Therefore,the study of the effect and molecular mechanism of Onvansertib in lung adenocarcinoma will provide new ideas and theoretical basis for the clinical diagnosis and treatment of lung adenocarcinoma.So,we tested its potential function in lung adenocarcinoma cells.Firstly,we used bioinformatics technology to analyze and found that the expression of PLK1 is high in lung adenocarcinoma,and interference of PLK1 can increase the apoptosis of lung adenocarcinoma cells,block cell cycle development and reduce the resistance of cisplatin.Onvansertib inhibited cell growth and cell cycle progression in A549 and PC-9 cells.In addition,it can inhibit cell migration and also significantly induce apoptosis.Moreover,Onvansertib increased ROS levels in cells and N-Acetyl-L-cysteine was able to reduce the increased ROS levels and reverse apoptosis caused by Onvansertib.Cisplatin,as an important representative of platinoid drugs,plays an anticancer role through the cell cycle and is also used as a first-line chemotherapy drug in the treatment of lung adenocarcinoma.Chemotherapy can achieve good clinical therapeutic effect,but lung cancer patients are also prone to chemotherapy resistance,which affects the treatment outcome.Although,there are many studies on the mechanism of drug resistance,the problem of cisplatin resistance is still not completely solved.So it is of important clinical significance to find ways to improve cisplatin resistance.Our study found that Onvansertib was beneficial to improve the cisplatin sensitivity of resistant A549 cells.Mechanistically,Onvansertib reduced the expression level of c Myc protein and its downstream genes.Overexpression of c Myc partially reversed Onvansertib-induced toxicity.Through the construction of CDX model and PDX model in nude mice,it was again confirmed that this inhibitor can inhibit tumor growth well.Cyclin-dependent kinase 7(CDK7),as an important member of the cyclin-dependent kinase family,has been widely concerned and researched.As a novel inhibitor targeting CDK7,mechanism of transcriptional inhibition from THZ2 has been validated in most tumors.There is no relevant data to support whether THZ2 has a good anticancer effect in lung adenocarcinoma.There is no relevant data to support whether THZ2 has a good anti-cancer effect in lung adenocarcinoma.We found that THZ2 inhibited the growth and cell cycle progression of lung adenocarcinoma cells.It also inhibits cell migration and invasion and induces cell apoptosis.Moreover,THZ2 increases intracellular ROS levels,and NAC reverses increased ROS levels and reduces apoptosis.Mechanically,THZ2 reduces the protein level of c Myc,and overexpression of c Myc can effectively reverse the inhibitory effect of THZ2 on tumor cells.Because both inhibitors can play a role to inhibit cancer through reducing expression of c Myc.Therefore,we study the combination of the two inhibitors.The results showed that Onvansertib and THZ2 can effectively exert the biological effects of inhibiting cell proliferation and inducing cell apoptosis,and play the synergistic role of drugs.