Background:　Heat　shock　protein　90　(HSP90)　functions　as　a　well-known　onco-protein　to　regulate　protein　conformation,　stability　and　degradation.　Pyruvate　kinase　M2　(PKM2),　a　critical　regulator　of　the　metabolism,　growth　and　metastasis　of　cancer　cells,　has　been　confirmed　to　be　overexpressed　in　various　human　cancer　including　hepatocellular　carcinoma　(HCC).　However,　the　molecular　mechanisms　underlying　the　oncogenic　functions　of　HSP90　and　PKM2　overexpression　in　HCC　remain　unknown.　Methods:　The　expression　of　HSP90　and　PKM2　in　HCC　specimens　and　cells　were　detected　by　immunoblotting　and　immunostaining.　The　interaction　between　HSP90　and　PKM2　was　confirmed　by　tandem　affinity　purification,　coimmunoprecipitation　and　Glutathione　S　transferase　(GST)-pulldown　assay.　Results:　In　this　study,　we　found　that　HSP90　could　bind　to　PKM2　and　subsequently　increased　PKM2　abundance　in　HCC　cells.　Immunohistochemistry　(IHC)　staining　showed　that　HSP90　level　was　positively　correlated　with　PKM2　level　in　HCC　tissues.　Mechanistically,　HSP90　was　found　to　increase　the　phosphorylation　of　PKM2　at　Thr-328.　Protein　kinase　glycogen　synthase　kinase-3　beta　(GSK-3　beta)　formed　a　protein　complex　with　HSP90　and　PKM2,　and　directly　mediated　Thr-328　phosphorylation　of　PKM2　induced　by　HSP90.　Thr-328　phosphorylation　was　critical　for　maintaining　PKM2　stability　and　its　biological　functions　in　regulating　glycolysis,　mitochondria　respiration,　proliferation　and　apoptosis.　Functionally,　we　found　that　HSP90　promoted　the　glycolysis　and　proliferation　and　inhibited　apoptosis　of　HCC　cells　in　a　PKM2　dependent　manner.　In　vivo　experiments　disclosed　that　PKM2　was　required　for　the　promoting　effects　of　HSP90　on　the　growth　of　HCC　cells　in　mice.　Furthermore,　we　demonstrated　that　positive　expression　of　HSP90　and　PKM2　was　correlated　with　poor　clinicopathological　features　including　high　alpha　fetoprotein　(AFP)　level,　large　tumor　size,　portal　vein　tumor　thrombus　(PVTT)　and　advanced　tumor-node-metastasis　(TNM)　stage.　Furthermore,　we　demonstrated　that　positive　expression　of　HSP90　and　PKM2,　and　a　combination　of　these　proteins　could　strongly　predict　the　poor　prognosis　of　HCC　patients.　Conclusions:　We　suggest　that　HSP90　potentiates　the　glycolysis　and　proliferation,　reduces　the　apoptosis　and　thus　enhances　the　growth　of　HCC　cells　through　PKM2.