T-cell leukemias and lymphomas are clinically aggressive cancers resistant to conventional chemotherapy regimens and in desperate need for novel therapeutic approaches. This proposal studies the pathogenesis of these hematologic neoplasms and directly benefits Veterans' health by advancing the development of targeted therapy, and precision medicine for these treatment-resistant cancers. Our laboratory has been studying T-cell neoplasms from the perspective of two major oncogenic pathways: the LIM domain Only-2 (LMO2) pathway and the IL2RG/JAK1/3/STAT5 cytokine signaling pathway. LMO2 is one of the most frequently deregulated oncogenes in T-cell acute lymphoblastic leukemia. LMO2 encodes a small 18 kDa protein that is part of a large multisubunit protein complex that regulates the transcription of key target genes. We have been dissecting the mechanism by which LMO2's enforced expression induces T-ALL and have discovered key pre-leukemic phenotypes enforced by LMO2 like differentiation arrest and enhanced self-renewal. The IL2RG/JAK1/3/STAT5 pathway is required for the development and function of lymphocytes and our lab discovered that gain of function in this pathway is common in both mature and immature T-cell neoplasms. In recent exciting data, our LMO2 and JAK3 work has converged in intriguing findings. Mutational and gene expression analyses show that LMO2 overexpression and JAK3 activating mutations are concordant hits in both mature and immature T-cell neoplasms. The results imply that these two pathways cooperate to induce T- cell transformation. Interestingly, enforced expression of LMO2 in double negative T-cell progenitors induces highly penetrant T-cell leukemias but double positive progenitors do not develop leukemia. Similarly, enforced expression of constitutively active mutant JAK3 does not induce disease on its own. We hypothesize that T-cell transformation into leukemia or lymphomas may manifest if these two pathways were concordantly activated. In this proposal, we will investigate the mechanistic basis of this cooperativity so that T-cell leukemias and lymphomas may be better targeted therapeutically.
In Aim 1, we will investigate the cooperativity between LMO2 and JAK3 oncogenes using bone marrow transduction and transplantation in our Lmo2 transgenic mouse model.
In Aim 2, we will analyze signal transduction within the IL2RG/JAK1/3/STAT5 pathway in leukemias and lymphomas induced in Lmo2 transgenic mice.
In Aim 3, we will test the use of JAK inhibitors against primary human T-cell neoplasms and analyze synergy with chemotherapy and LMO2 knockdown.
The Aims will establish a foundation for the development of novel biomarkers and novel therapeutic approaches based on LMO2 and IL2RG/JAK1/3/STAT5 pathways.

Public Health Relevance

This proposal studies the pathogenesis of T-cell leukemias and lymphomas and directly benefits Veterans' health by advancing the development of targeted therapy and biomarkers. We will study specific genetic mutations and how they interact to cause these aggressive hematologic malignancies. The studies provide a foundation for the development of novel therapeutic targets in these treatment-resistant cancers.

National Institute of Health (NIH)
Veterans Affairs (VA)
Non-HHS Research Projects (I01)
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Hematology (HEMA)
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Rlr VA Medical Center
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Greenplate, Allison; Wang, Kai; Tripathi, Rati M et al. (2018) Genomic Profiling of T-Cell Neoplasms Reveals Frequent JAK1 and JAK3 Mutations With Clonal Evasion From Targeted Therapies. JCO Precis Oncol 2018:
Efimenko, Evgeni; Davé, Utpal P; Lebedeva, Irina V et al. (2017) PI3K?/? and NOTCH1 Cross-Regulate Pathways That Define the T-cell Acute Lymphoblastic Leukemia Disease Signature. Mol Cancer Ther 16:2069-2082
Layer, Justin H; Alford, Catherine E; McDonald, W Hayes et al. (2016) LMO2 Oncoprotein Stability in T-Cell Leukemia Requires Direct LDB1 Binding. Mol Cell Biol 36:488-506
Goodings, Charnise; Smith, Elizabeth; Mathias, Elizabeth et al. (2015) Hhex is Required at Multiple Stages of Adult Hematopoietic Stem and Progenitor Cell Differentiation. Stem Cells 33:2628-41
McGirt, Laura Y; Jia, Peilin; Baerenwald, Devin A et al. (2015) Whole-genome sequencing reveals oncogenic mutations in mycosis fungoides. Blood 126:508-19
Goodings, Charnise; Tripathi, Rati; Cleveland, Susan M et al. (2015) Enforced expression of E47 has differential effects on Lmo2-induced T-cell leukemias. Leuk Res 39:100-9
Cleveland, Susan M; Goodings, Charnise; Tripathi, Rati M et al. (2014) LMO2 induces T-cell leukemia with epigenetic deregulation of CD4. Exp Hematol 42:581-93.e5
Smith, Stephen; Tripathi, Rati; Goodings, Charnise et al. (2014) LIM domain only-2 (LMO2) induces T-cell leukemia by two distinct pathways. PLoS One 9:e85883
Cleveland, Susan M; Smith, Stephen; Tripathi, Rati et al. (2013) Lmo2 induces hematopoietic stem cell-like features in T-cell progenitor cells prior to leukemia. Stem Cells 31:882-94
Yan, Ling; Womack, Bethany; Wotton, David et al. (2013) Tgif1 regulates quiescence and self-renewal of hematopoietic stem cells. Mol Cell Biol 33:4824-33

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