mCG-PML-RARA alters multipotent hematopoiesis

Acute promyelocytic leukemia (APL) is associated with PML-RARA expression and late myeloid maturation arrest. The myeloid restriction of PML-RARA dependent leukemia has been recapitulated in multiple mouse models of APL, including PML-RARA expressed from the Ctsg locus (mCG-PR). However, we report here that Ctsg expression is not limited to promyelocytes (as had previously been thought); Ctsg RNA is detectable in KLS cells, and mCG-PR mice express PML-RARA within the same compartment, an event that alters multilineage hematopoiesis. However, these animals only develop myeloid leukemia (consistent with the myeloid restriction of human PML-RARA-associated leukemia). Our results suggest that APL is shaped by myeloid- and development-specific factors that define the ultimate leukemic phenotype rather than PML-RARA acting in a committed myeloid precursor. Bone marrow from individual mice expressing PML-RARA from the murine Ctg locus (mCG-PR) and littermate controls was harvested from both femurs and tibia. Standard cell lysis was performed and total RNA was extracted from the flow sorted KLS and SLAM cells. A total of 13 specimens including 3 x mCG-PR_KLS_6wks, 2 x mCG-PR_KLS_13wks,2 x mCG-PR_SLAM_7wks, 4 x WT_KLS_12-13wks (control) and 2 x WT_SLAM_6wks (control) were analyzed using Affymetrics Mouse Exon 1.0 ST platform.