The Function And Mechanism Of MNX1-AS1 In The Proliferation Of Lung Cancer

Objective:Lung cancer is one of the most common cancers,and is the leading cause of cancer-related death.Recent years,long non-coding RNA(Lnc RNA)has attracted more and more attention due to its involvement in tumorigenesis and development.In our previous study,MNX1-AS1 was found to be differentially expressed in TGF-β-induced A549 cell EMT model,and could affect the invasion and metastasis ability of lung cancer cells.However,the effect of MNX1-AS1 on the proliferation and cell cycle control,as well as its underling mechanism in lung cancer cells is still unclear.In this study,we aimed to explore the role and mechanism of MNX1-AS1 in the proliferation and cell cycle control of lung cancer.Methods:(1)Online Database was used to analyze the expression of MNX1-AS1 in lung adenocarcinoma cancer tissues as well as the association of MNX1-AS1 with the prognosis of lung cancer patients,and refered to the functional enrichment of MNX1-AS1-related genes;the expression level of MNX1-AS1 was also detected by q-PCR in 42 pairs of lung cancer tissues and adjacent tissues.(2)The cell lines with stable expression and knockdown of MNX1-AS1 were constructed;the cell proliferation ability was then detected by CCK-8 and cloning formation assays,while cell cycle distribution was detected by using flow cytometry.(3)The protein levels of Wnt/β-atenin pathway-related proteins,Cyclin D1,c-Myc and β-catenin,as well as the two phosphorylation sites of GSK3β were detected by using Western Blot.(4)Nucleus and cytoplasmic proteins were extracted separately to detect the effect of MNX1-AS1 on the localization of β-catenin.(5)The effect of MNX1-AS1 on β-catenin m RNA level was detected by q-PCR.(6)The correlation between MNX1-AS1 and its host gene MNX1 in lung cancer was refered to and detected by Online Database and q-PCR,respectively.Results:(1)MNX1-AS1 was highly expressed in lung cancer tissues,and associated with poor prognosis of patients with lung cancer.(2)The function of MNX1-AS1-correlated genes was related to the cell cycle progression.(3)Stable high expression of MNX1-AS1 promoted the growth of lung cancer cells in vitro,and knockdown of MNX1-AS1 decreased the growth of lung cancer cells in vitro;stable high expression of MNX1-AS1 led to a decrease in G0/G1 phase and an increase in S phase of lung cancer cells.(4)After stable expression of MNX1-AS1,the expression of Cyclin D1,c-Myc and β-catenin were upregulated,phosphorylation of GSK3β Tyr216 active site was attenuated,and phosphorylation of GSK3β Ser9 active site was increased.(5)Stable high expression of MNX1-AS1 resulted in increased β-catenin levels in both nucleu and cytoplasm,while knockdown of MNX1-AS1 led to decreased β-catenin levels in both nuclear and cytoplasm.(6)High expression or knockdown of MNX1-AS1 did not affect the β-catenin m RNA levels.(7)There was a positive correlation between the expression levels of MNX1-AS1 and its host gene MNX1 in lung cancer.Conclusion:MNX1-AS1 is overexpressed in lung cancer tissues.MNX1-AS1 could promote the proliferation and cell cycle progression of lung cancer cells.MNX1-AS1 inhibites the activity of GSK3β,increases the content of β-catenin,and promotes the entry of β-catenin into the nucleus,thus leading to activation of downstream target Cyclin D1 and c-Myc.MNX1-AS1 also has a positive correlation with the host gene MNX1 in RNA level.