Roles Of CDK3/KLF4 In The Metastasia Of Lung Cancer

Objective: The function of cyclin dependent kinase 3(CDK3)in the metastasis of lung cancer is unclear.Our previous data has shown that CDK3 phosphorylated the krüppel-like factor 4(KLF4)at serine 244(Ser244).This research aims to investigate the role of CDK3/KLF4 in the metastasis of lung cancer.Method:(1)Immunoblotting was performed to exam the expression of CDK3 and KLF4 in several lung cancer cell lines.(2)The expression of CDK3 and KLF4 in clinical sample was studied by analysis of TCGA database,and immunohistochemical(IHC)staining of lung cancer tissue array and clinical samples.(3)Stable transfected lung cancer cell lines were constructed and applied to investigate impact of CDK3 on migration and invasion by using Transwell migration assay and Transwell invasion assay.(4)Stable transfected lung cancer cell lines were constructed and applied to investigate impact of KLF4 and KLF4 mutant(S244A)on migration and invasion by using Transwell migration assay and Transwell invasion assay.(5)Animal model of metastasis was used to investigate impact of CDK3,KLF4 and KLF4 mutant(S244A)on metastasis in vivo.(6)The signaling pathways of CDK3/KLF4 inhibited metastasis of lung cancer cells.(7)qPCR was performed to study transcriptionally regulation of KLF4 to CDK3.Result:(1)Overexpression of CDK3 suppressed cell migration and invasion of lung cancer cells.(2)Overexpression of KLF4 suppressed cell migration and invasion of lung cancer cells.In contrast,overexpression of KLF4-S244 A could not inhibit the migration and invasion of lung cancer cells.(3)Either CDK3 or KLF4 may inhibit metastasis of A549 cell in vivo in nude mice.(4)Western blot results showed overexpressing of KLF4 down-regulated Snail,Slug,N-cadherin and Vimentin expression,thereby suppressing epithelial-mesenchymal transitions(EMT).However,it is unknown yet whether the KLF4 mutant(KLF4-S244A)weaken this EMT suppresssing event.(5)qPCR results showed CDK3 mRNA expression was up-regulated in lung cancer cell line overexpressing KLF4.Conclusion:(1)CDK3 can inhibit the metastasis of lung cancer.(2)KLF4 can inhibit the metastasis of lung cancer.(3)Ser244 of KLF4 is critical to its inhibitory function on cancer metastasis.(4)KLF4 inhibits EMT in lung cancer cells,the effect of KLF4-S244 A for EMT is still remains to be studied.(5)CDK3 m RNA expression was up-regulated in lung cancer cell line overexpressing KLF4,this indicates KLF4 might have transcriptional feedback on CDK3.