Effect of miR-375 on non-small cell lung carcinoma invasion,migration,and proliferation through the CIP2A pathway

摘要

Lung cancer is one of the malignant tumors with the fastest increase in morbidity and mortality and the greatest threat to people’s health and life.Worldwide,lung cancer is the leading cause of cancer death in men and the second leading cause of cancer deaths in women[1].Lung cancer is divided into two major groups,small cell lung cancer(SCLC)and non-small cell lung cancer(NSCLC)[2].SCLC accounts for approximately 20%of lung cancers.It has a high degree of malignancy and early metastasis,and is sensitive to chemotherapy and radiotherapy.The initial remission rate is high,but it is prone to secondary drug resistance and relapse.Chemotherapy is the mainstay.NSCLC includes three major histological subtypes,lung squamous cell carcinoma(SCC),lung adenocarcinoma(ADC),and large cell lung cancer(LCLC),accounting for approximately 80%of lung cancers.Cell division is slower,and the diffusion shift is relatively late[3].Nevertheless,while current research on the biological characteristics of different histological subtypes of NSCLC is expanding,its basic molecular mechanism is not yet clear.For example,smoking is more risky for SCC than ADC[4].Micro-RNA is an endogenous small RNA with a length of approximately 19–25 nucleotides.As a short non-coding RNA,its main function is to regulate the expression level of mRNA.miRNAs can be used as proto-oncogenes or tumor suppressors,and participate in various processes including proliferation,apoptosis,metabolism,and differentiation of cells through targeted binding to different transcripts[5].miRNAs are expressed in specific tissue and developmental stages under normal physiological conditions,but abnormal expression of miRNAs can lead to a series of pathological states,such as tumorigenesis and metastasis[6–7].miRNA regulates the function of tumor cells by regulating the expression of functional proteins.For example,miR-206 promotes breast cancer proliferation by inhibiting estrogen receptor alpha(ERα)while miR-34a downregulates E2 factor transcription factor 2(E2F2)expression to regulate the cell cycle and apoptosis[8–9].CIP2A,as an oncogenic protein during the malignant transformation and progression of cancer cells,has been shown to have a certain relationship with the efficacy of many drugs in cancer treatment.Oncoprotein CIP2A,also known as KIAA1524 or P90,was named in 2007 and is a cancerous inhibitor of PP2A due to its effect on cancer cells.The stability of PP2A and MYC is controlled to form a"carcinogenic connection"[10].In this study,we found that miR-375 regulated the expression of downstream protein kinase B(AKT),MYC,p-AKT and other related proteins through the CIP2A/PP2A signaling pathway,inhibiting the cancer phenotype of lung cancer,and affecting cell invasion,proliferation,apoptosis,and the cell morphology process.We found that the CIP2A gene is a direct binding target of miR-375.Thus,it has become a topic of great interest to explore whether and how miR-375 regulates ADC cells through the CIP2A signaling pathway.By up-regulating miR-375 in a lentivirus-transfected A549 cell line,we found that a series of phenotypes,including cell invasion,proliferation,and apoptosis were changed,and that CIP2A and its downstream signaling proteins were also changed.