Liver　kinase　B1　(LKB1)　as　a　tumor　suppression　gene　that　is　associated　with　various　kinds　of　cancers,　including　lung　cancer.　In　this　study,　we　found　that　the　effect　of　LKB1　on　tumor　growth　was　dependent　on　its　subcellular　expression　in　A549　and　HCC827　cells.　Full-length　LKB1　decreased　the　proliferation　and　clonogenicity　of　A549-LKB1　and　HCC827-LKB1　cells,　but　increased　their　apoptosis.　Opposite　effects　were　observed　in　A549-LKB1(s)　and　HCC827-LKB1(S)　cells　that　overexpressed　truncated　LKB1　without　the　nuclear　localization　sequence.　The　truncated　cytoplasmic　LKB1　enhanced　the　growth　of　implanted　tumors　invivo.　The　truncated　cytoplasmic　LKB1　promoted　autophagy,　which　was　independent　of　AMP-activated　protein　kinase　and　mTOR　signaling　in　A549　and　HCC827　cells.　Further　characterization　indicated　that　higher　levels　of　cytoplasmic　LKB1　expression　were　associated　with　advanced　TNM　stage　and　reduced　overall　survival　(OS)　in　190　patients　with　adenocarcinoma.　In　contrast,　high　nuclear　expression　of　LKB1　is　associated　with　early　TNM　stage　and　longer　OS.　The　high　level　of　cytoplasmic　LKB1　expression　was　an　independent　risk　factor　for　poor　overall　survival　in　patients　with　adenocarcinoma.　Together,　our　results　revealed　that　cytoplasmic　LKB1　promotes　the　growth　of　lung　adenocarcinoma　and　could　be　a　prognostic　marker　for　lung　adenocarcinoma.