Translocation-generated ITK-FER and ITK-SYK fusions induce STAT3 phosphorylation and CD69 expression

Highlights: • The downstream targets of ITK-FER and ITK-SYK were explored and STAT3 is highly phosphorylated by these fusion kinases. • The CD69 T-cell activation marker was significantly elevated. • Upon expression of FER, ITK-FER, SYK, and ITK-SYK, the auto-phosphorylation events in HEK 293T cells were induced, even under serum starvations. Many cancer types carry mutations in protein tyrosine kinase (PTK) and such alterations frequently drive tumor progression. One category is gene translocation of PTKs yielding chimeric proteins with transforming capacity. In this study, we characterized the role of ITK-FER [Interleukin-2-inducible T-cell Kinase (ITK) gene fused with Feline Encephalitis Virus-Related kinase (FER) gene] and ITK-SYK [Interleukin-2-inducible T-cell Kinase (ITK) gene fused with the Spleen Tyrosine Kinase (SYK)] in Peripheral T Cell Lymphoma (PTCL) signaling. We observed an induction of tyrosine phosphorylation events in the presence of both ITK-FER and ITK-SYK. The downstream targets of ITK-FER and ITK-SYK were explored and STAT3 was found to be highly phosphorylated by these fusion kinases. In addition, the CD69 T-cell activation marker was significantly elevated. Apart from tyrosine kinase inhibitors acting directly on the fusions, we believe that drugs acting on downstream targets could serve as alternative cancer therapies for fusion PTKs.