SPINK2 silencing suppresses leukemic proliferation and restores myeloid commitment via MECOM downregulation in acute myeloid leukaemia

: Myeloid leukaemias harboring complex karyotypes present several unrelated cytogenetic abnormalities and form a distinct subset of AML linked to a dismal prognosis. Currently, no effective options are available for the treatment of those patients, and the discovery of novel therapeutic strategies represent an urgent clinical priority. We previously developed a bioinformatic framework for the identification of novel molecular vulnerabilities for disease stratification and treatment and observed SPINK2, a serine protease inhibitor Kazal-type 2, as a novel and promising candidate target in AML, with particularly pronounced effects in complex karyotype patients. Using publicly available bulk and single cell RNA-seq datasets, we discovered a robust association between SPINK2 and cell cycle regulators, most notably S-phase genes. By performing shRNA-mediated genetic manipulation of SPINK2 expression in a complex karyotype AML cell lines, we observed a profound impairment of proliferation coupled with an induction of terminal myeloid commitment. Moreover, SPINK2-deficient FUJIOKA cells revealed a significant association between SPINK2 and MECOM expression, consistent with findings in patients harbouring complex karyotypes, yet absent in other AML subsets from the TARGET-AML cohort. Our findings suggest a novel potential correlation between SPINK2 and MECOM expression in complex karyotype leukemias and warrant further investigation into the underlying molecular mechanisms through which the SPINK2-MECOM axis enforces aberrant self-renewal and the development of novel targeted approaches aimed at modulating its expression in complex karyotypic AML.