Critical role of cytokine and growth factor receptors in AML identified using an RNAi functional screen  — ASN Events
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  3. Critical role of cytokine and growth factor receptors in AML identified using an RNAi functional screen 

Critical role of cytokine and growth factor receptors in AML identified using an RNAi functional screen  (#349)

Kevin M Watanabe-Smith 1 2 3 , Ryan J MacKenzie 1 3 , Christopher A Eide 1 3 4 , Alyssa B Carey 1 3 , Monika A Davare 5 6 , Cristina E Tognon 3 4 , Rita M Braziel 7 , Jeffrey W Tyner 3 8 , Brian J Druker 1 3 4 , Anupriya Agarwal 1 3
  1. Division of Hematology and Medical Oncology, Oregon Health and Science University, Portland, OR, United States
  2. Cancer Biology Program, Oregon Health and Science University, Portland, OR, United States
  3. Knight Cancer Institute, Oregon Health and Science University, Portland, OR, United States
  4. Howard Hughes Medical Institute, Portland, OR, United States
  5. Department of Pediatrics, Oregon Health and Science University, Portland, OR, United States
  6. Department of Pediatrics, Oregon Health and Science University, Portland, OR, United States
  7. Department of Pathology, Oregon Health and Science University, Portland, OR, United States
  8. Department of Cell & Developmental Biology, Oregon Health and Science University, Portland, OR, United States

Methods: Acute myeloid leukemia (AML) is one of the most common hematologic malignancies affecting both children and adults. Because cytokine and growth factor receptors contribute to cancer pathogenesis by regulating growth, differentiation, and survival1 2 3 , we designed a functional RNAi screen targeting 188 cytokine and growth factor receptors that we found highly expressed in primary leukemia specimens. Using this screen we identified interleukin-2 gamma receptor (IL2Rγ) and Colony Stimulating Factor 2 Receptor Beta (CSF2RB)as critical growth determinants for JAK3 mutation-positive AML cells.

Results: We observed that knockdown of IL2Rγ reduced the growth of JAK3 mutation-positive AML cells and abrogates phosphorylation of JAK3 and downstream signaling molecules, JAK1, STAT5, MAPK and pS6 ribosomal protein. Overexpression of IL2Rγ in murine cells increased the transforming potential of activating JAK3 mutations, whereas absence of IL2Rγ completely abrogated the clonogenic potential of JAK3A572V mutation-positive cells. In addition, mutation at the IL2Rγ interaction site in the FERM domain of JAK3 (Y100C) completely abrogated JAK3-mediated leukemic transformation. Mechanistically, IL2Rγ and JAK3 contribute to constitutive JAK/STAT signaling through their reciprocal regulation.

Additionally, CSF2RB was identified as a secondary hit in CMK cells and siRNA-mediated knockdown reduced cellular viability and phosphorylation of JAK2, STAT5, ERK1/2 and S6 ribosomal protein. CSF2RB is highly expressed in 30% of AMLs4  and preliminary data shows some primary AMLs may depend on CSF2RB expression, indicating a potential therapeutic target.

Conclusions:  We have demonstrated: 1) A novel role for IL2Rγ in potentiating oncogenesis in the setting of JAK3-mutation-positive leukemia. 2) CSF2RB is a potential functional target in AML and future studies investigating this possibility may yield novel therapeutic strategies. 3) RNAi-based functional assays can be used to facilitate the identification of non-kinase cytokine and growth factor receptor targets for inhibiting leukemic cell growth.

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  2. Van Etten RA. Aberrant cytokine signaling in leukemia. Oncogene. 2007 Oct 15;26(47):6738-49. PubMed PMID: 17934482.
  3. Vainchenker W, Constantinescu SN. JAK/STAT signaling in hematological malignancies. Oncogene. 2013 May 23;32(21):2601-13. PubMed PMID: 22869151.
  4. Riccioni R, Diverio D, Riti V, Buffolino S, Mariani G, Boe A, Cedrone M, Ottone T, Foa R, Testa U. Interleukin (IL)-3/granulocyte macrophage-colony stimulating factor/IL-5 receptor alpha and beta chains are preferentially expressed in acute myeloid leukemias with mutated FMS-related tyrosine kinase 3 receptor. Br J Haematol. 2009 Feb;144(3):376-87. PubMed PMID: 19036083