Whole exome sequencing of 12 tumor-normal DNA pairs, RNAseq analysis and targeted deep sequencing identified new genetic alterations in PTCL transformation. These analyses identified highly recurrent epigenetic factor mutations in TET2, DN-MT3A and IDH2 as well as a new highly prevalent RHOA p.Gly17Val (NM_001664) mutation present in 22/35 (67%) of angioimmunoblastic T-cell lymphomas (AITL) and in 8/44 (18%) not otherwise specified PTCL (PTCL NOS) samples. Mechanistically, the RHOA Gly17Val protein interferes with RHOA signaling in biochemical and cellular assays, an effect potentially mediated by the sequestration of activated Guanine Exchange Factor (GEF) proteins. In addition, new and recurrent, genetic defects are described including mutations in FYN, ATM, B2M and CD58 implicating SRC signaling, impaired DNA damage response and escape from immune surveillance mechanisms in the pathogenesis of PTCL.
