👤 Melanie G Cornejo

Testicular adult granulosa cell tumors (AGCTs) are rare and show several clinical, pathological, and molecular differences with their ovarian counterparts. FOXL2 p.Cys134Trp, the ubiquitous molecular driver of ovarian AGCTs, is infrequent (~ 7%) in testicular AGCTs. Recently, FGFR1 hotspot mutations were reported as a potentially "alternative molecular driver" in FOXL2-wild type (WT) ovarian AGCTs. A systematic assessment of FGFR1 status has not been performed in testicular AGCTs. Recently, our group analyzed a series of twenty testicular AGCTs using two NGS panels that lacked coverage of FGFR1. Among twelve cases analyzed successfully, none harbored pathogenic FOXL2 variants. In this study, we reassessed the tumors from our prior series with an NGS panel that covers FGFR1. Among the 14 tumors (70%) that were sequenced successfully, none harbored pathogenic FGFR1 variants. Considering the AGCTs assessed in this study and those previously reported in the literature, none of the 24 tumors analyzed to date have shown pathogenic FGFR1 variants. The present study reinforces the concept that testicular sex cord-stromal tumors classified as AGCTs are different from ovarian counterparts. Show less

Activated tyrosine kinases have been frequently implicated in the pathogenesis of cancer, including acute myeloid leukemia (AML), and are validated targets for therapeutic intervention with small-molecule kinase inhibitors. To identify novel activated tyrosine kinases in AML, we used a discovery platform consisting of immunoaffinity profiling coupled to mass spectrometry that identifies large numbers of tyrosine-phosphorylated proteins, including active kinases. This method revealed the presence of an activated colony-stimulating factor 1 receptor (CSF1R) kinase in the acute megakaryoblastic leukemia (AMKL) cell line MKPL-1. Further studies using siRNA and a small-molecule inhibitor showed that CSF1R is essential for the growth and survival of MKPL-1 cells. DNA sequence analysis of cDNA generated by 5'RACE from CSF1R coding sequences identified a novel fusion of the RNA binding motif 6 (RBM6) gene to CSF1R gene generated presumably by a t(3;5)(p21;q33) translocation. Expression of the RBM6-CSF1R fusion protein conferred interleukin-3 (IL-3)-independent growth in BaF3 cells, and induces a myeloid proliferative disease (MPD) with features of megakaryoblastic leukemia in a murine transplant model. These findings identify a novel potential therapeutic target in leukemogenesis, and demonstrate the utility of phosphoproteomic strategies for discovery of tyrosine kinase alleles. Show less