Analysis of novel antagonists of the GRB2 SH2 domain that decrease proliferation in chronic myeloid leukemia (CML)

95% of the cases of chronic myeloid leukemia (CML) are caused by a chromosomal translocation linking the breakpoint cluster region (BCR) gene to the Abelson murine leukemia viral oncogene-1 (ABL1). Downstream of BCR-ABL is growth receptor bound protein-2 (GRB2), which binds to BCR-ABL via its src-homology-2 (SH2) domain. This binding constitutively activates growth pathways while down regulating apoptosis leading to an over proliferation of immature and dysfunctional myeloid cells. Four novel SH2 antagonists were developed with three of the four showing a significant reduction in proliferation of a BCR-ABL+ leukemia cell line. To elucidate the mechanism of action, an enzyme-linked immunosorbent assay (ELISA), a surface plasmon resonance (SPR) assay, and a cellulose nitrate (CN) filter assay were performed. These assays indicated that one of the three effective molecules, NHD2-15, antagonized the SH2 domain of GRB2 with a Kd value of 119 ± 2 μM, bringing us closer to developing a new treatment for CML.