My laboratory’s interest over a long period has been how hyperactive protein kinase signaling drives tumorigenesis and how to target oncogenic protein kinases for cancer therapy. Protein kinases play a critical role in the pathogenesis of many human diseases including cancers, and their regulations involve in the assembly of two hydrophobic cores named as “Catalytic Spine” and “Regulatory Spine”. In last years, we had constructed a set of Spine-related mutagenesis methods and unraveled the molecular mechanism underlying the dimerization-driven transactivation of RAF kinase by using these methods (Hu et al., PNAS, 2011; Hu et al., Cell, 2013; Hu et al., Mol. Cell Biol., 2015). These works provide us an excellent basis for further exploring how RAF/MEK/ERK kinase cascade is altered in cancers and thereby developing novel inhibitors for cancer targeted therapy. Recently, we identified a group of oncogenic RAF/MEK mutants with variable β3-αC loop deletions (Yuan et al., Oncogene, 2018; Yuan et al., Science Signaling, 2018). By utilizing their unique characteristics, we have demonstrated that the signal is transduced in a dimer-to-dimer manner in RAF/MEK/ERK kinase cascade. Currently, we are developing next-generation of RAF/MEK inhibitors by targeting the protein interactions among this kinase cascade.
The second research theme at my laboratory is to construct effective approaches to overcome the drug resistance in the treatment of BRAF(V600E)-harboring cancers. BRAF(V600E) is a dominant RAF mutant in cancer genomes, and to target this mutant, the first generation RAF inhibitors have been developed and applied to clinic treatment. Unfortunately, their efficacy is abrogated in a short term by acquired resistance arising from RTK/Ras alterations or alternative splicing of BRAF(V600E). We have identified AMPK as a potential target to overcome RTK/Ras alteration-induced drug resistance (Yuan et al., JBC, 2018), although further investigations are required. To block the aberrant splicing of BRAF(V600E), we are carrying out whole-genome screening to identify potential factors that may service as targets to overcome this type of resistance. These studies would not only provide us insight for how RAF/MEK/ERK signaling is altered in cancers, but also improve the targeted therapies against this pathway.
Lastly, my laboratory still works on genetic mouse models of cancers that can be used to investigate the pathogenesis of different cancers and as platforms for cancer drug evaluation. We have developed a hairy cell leukemia mouse model by introducing BRAF(V600E) mutation and depleting tumor suppressor in mature B cells. Using this mouse model, we are examining the molecular mechanisms that underlie the pathological features of hairy cell leukemia, and developing novel strategies for hairy cell leukemia treatment. Other cancer mouse models under developing at my laboratory include BRAF(V600E)-driven intrahepatic cholangiocarcinoma and Kras(G12D)-driven hepatocellular carcinoma.
Selected Publications and Manuscripts:
Yuan J, Ng WH, Lam P, Wang Y, Xia H, Yap JJ, Guan SP, Lee A, Wang M, Baccarini M, and Hu J. The Dimer-dependent Catalytic Activity of RAF Family Kinases Is Revealed Through Characterizing Their Oncogenic Mutants. Oncogene. 2018; 37:5719-5734.
Yuan J, Ng WH, Tian Z, Yap JJ, Baccarini M, Chen Z and Hu J.Activating mutations in MEK1 enhance homodimerization and promote tumorigenesis. Science Signaling. 2018; 11: eaar6795.
Yuan J, Ng WH, Yap JJ, Chia B, Huang X, Wang M and Hu J. The AMPK inhibitor overcomes the paradoxical effect of RAF inhibitors through blocking the phospho-Ser-621 in the carboxyl-terminus of CRAF. Journal of Biological Chemistry. 2018; 293(37):14276-14284.
Xu X, Wang X, Todd EM, Jaeger ER, Vella JL, Mooren OL, Feng Y, Hu J, Cooper JA, Morley SC, and Huang YH. Mst1 kinase regulates the actin-bundling protein L-plastin to promote T cell migration. The Journal of Immunology. 2016; 197(5):1683-1691.
Chung JJ, Huber TB, Gödel M, Jarad G, Hartleben B, Kwoh C, Keil A, Karpitskiy A, Hu J, Huh CJ, Cella M, Gross RW, Miner JH, and Shaw AS. Albumin-associated free fatty acids induce macropinocytosis in podocytes. The Journal of Clinic Investigation. 2015; 125(6): 2307-16.
Hu J, Ahuja LG, Meharena HS, Kannan N, Kornev AP, Taylor SS, Shaw AS. Kinase Regulation by Hydrophobic Spine Assembly in Cancer. Molecular and Cellular Biology. 2015; 35(1): 264-276.
Wang X*, Boyken SE*, Hu J, Xu X, Rimer RP, Shea MA, Shaw AS, Andreotti AH and Huang YH. Calmodulin and PI(3,4,5)P₃ cooperatively bind to the Itk pleckstrin homology domain to promote efficient calcium signaling and IL-17A production. Science Signaling. 2014; 7(337), ra74.
Shaw AS, Kornev AP, Hu J, Ahuja LG, Taylor SS. Kinases and Pseudokinases: Lessons from RAF. Molecular and Cellular Biology. 2014; 34(9): 1538-46. (Review)
Hu J*, Oda SK*, Donovan EE, Shotts K, Strauch P, Pujanaushi LM, Victorino F, Al-Shami A, Fujiwara Y, Tigyi G, Oravecz T, Pelanda R and Torres RM. Lysophosphatidic acid (LPA) receptor 5 inhibits B Cell antigen receptor signaling and antibody response. The Journal of Immunology. 2014; 193(1): 85-95.
Hu J, Stites EC, Yu H, Germino E, Meharena HS, Stork PJS, Kornev AP, Taylor SS, Shaw AS. Allosteric activation of functionally asymmetric Raf kinase dimers. Cell. 2013; 154(5): 1036-1046.
Taylor SS, Shaw AS, Hu J, Meharena HS, Kornev AP. Pseudokinases from a structural perspective. Biochemical Society transactions. 2013; 41(4): 981-986. (Review)
Banchereau J, Zurawski S, Thompson-Snipes L, Blanck JP, Clayton S, Munk A, Cao Y, Wang Z, Khandelwal S, Hu J, McCoy WH, Palucka KA, Reiter Y, Fremont DH, Zurawski G, Colonna M, Shaw AS, Klechevsky E. Immunoglobulin-like transcript receptors on human dermal CD14+ dendritic cells act as a CD8-antagonist to control cytotoxic T cell priming. Proc Natl Acad Sci U S A. 2012; 109(46): 18885-90
Hu J, Yu H, Kornev AP, Zhao J, Filbert EL, Taylor SS, Shaw AS. Mutation that blocks ATP binding creates a pseudokinase stabilizing the scaffolding function of kinase suppressor of Ras, CRAF and BRAF. Proc Natl Acad Sci U S A. 2011; 108(15): 6067-72.
Hu J, Strauch P, Rubtsov A, Donovan EE, Pelanda R, Torres RM. Lsc activity is controlled by oligomerization and regulates integrin adhesion. Molecular Immunology. 2008; 45(7): 1825-36.
Rubtsov A, Strauch P, DiGiacomo A, Hu JC, Pelanda R, Torres RM. Lsc regulates marginal-zone B cell migration and adhesion and is required for the IgM T-dependent antibody response. Immunity. 2005; 23 (5): 527- 538.
Xu LG*, Wu M*, Hu JC, Zhai ZH, Shu HB. Identification of downstream genes up-regulated by the tumor necrosis factor family member TALL-1. Journal of Leukocyte Biology. 2002; 72 (2): 410-416.
Jiang Z, Hong X, Long H, Hu J, Zhai Z. Ceramides induce apoptosis in HeLa cells and enhance cytochrome c-induced apoptosis in Xenopus egg extracts. Cellular and Molecular Life Sciences. 2000; 57 (7): 1117-1125.