Kinase signaling fuels growth of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Yet its role in leukemia initiation is unclear and has not been shown in primary human hematopoietic cells. We previously described activating mutations in interleukin-7 receptor alpha (IL7RA) in poor-prognosis “ph-like” BCP-ALL. Here we show that expression of activated mutant IL7RA in human CD34+ hematopoietic cells creates a preleukemic state in transplanted NOD/LtSz-scid IL2Rγnull mice, characterized by persistence of self-renewing Pro-B cells with non-productive V(D)J gene rearrangements. Preleukemic CD34+CD10highCD19+ cells evolved to a BCP-ALL with spontaneously acquired CDKN2A deletions as commonly observed in primary human BCP-ALL. CRISPR mediated silencing of CDKN2A in primary human CD34+ cells transduced with activated IL7RA resulted in robust development of BCP-ALLs in-vivo. Thus, we demonstrate for the first time that constitutive activation of IL7RA can initiate preleukemia in primary human hematopoietic progenitors and cooperates with CDKN2A silencing in progression into ... (Show More)

Kinase signaling fuels growth of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Yet its role in leukemia initiation is unclear and has not been shown in primary human hematopoietic cells. We previously described activating mutations in interleukin-7 receptor alpha (IL7RA) in poor-prognosis “ph-like” BCP-ALL. Here we show that expression of activated mutant IL7RA in human CD34+ hematopoietic cells creates a preleukemic state in transplanted NOD/LtSz-scid IL2Rγnull mice, characterized by persistence of self-renewing Pro-B cells with non-productive V(D)J gene rearrangements. Preleukemic CD34+CD10highCD19+ cells evolved to a BCP-ALL with spontaneously acquired CDKN2A deletions as commonly observed in primary human BCP-ALL. CRISPR mediated silencing of CDKN2A in primary human CD34+ cells transduced with activated IL7RA resulted in robust development of BCP-ALLs in-vivo. Thus, we demonstrate for the first time that constitutive activation of IL7RA can initiate preleukemia in primary human hematopoietic progenitors and cooperates with CDKN2A silencing in progression into BCP-ALL.

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