PDE4DIP contributes to colorectal cancer growth and chemoresistance through modulation of the NF1/RAS signaling axis

Phosphodiesterase 4D interacting protein (PDE4DIP) is a centrosome/Golgi protein associated with cyclic nucleotide phosphodiesterases. PDE4DIP is commonly mutated in human cancers, and its alteration in mice leads to a predisposition to intestinal cancer. However, the biological function of PDE4DIP in human cancer remains obscure. Here, we report for the first time the oncogenic role of PDE4DIP in colorectal cancer (CRC) growth and adaptive MEK inhibitor (MEKi) resistance. We show that the expression of PDE4DIP is upregulated in CRC tissues and associated with the clinical characteristics and poor prognosis of CRC patients. Knockdown of PDE4DIP impairs the growth of KRAS-mutant CRC cells by inhibiting the core RAS signaling pathway. PDE4DIP plays an essential role in the full activation of oncogenic RAS/ERK signaling by suppressing the expression of the RAS GTPase-activating protein (RasGAP) neurofibromin (NF1). Mechanistically, PDE4DIP promotes the recruitment of PLC?/PKCe to the Golgi apparatus, leading to constitutive activation of PKCe, which triggers the degradation of NF1. Upregulation of PDE4DIP results in adaptive MEKi resistance in KRAS-mutant CRC by reactivating the RAS/ERK pathway. Our work reveals a novel functional link between PDE4DIP and NF1/RAS signal transduction and suggests that targeting PDE4DIP is a promising therapeutic strategy for KRAS-mutant CRC.

Automated summary

Phosphodiesterase 4D interacting protein (PDE4DIP) is found to be commonly mutated in human cancers and plays an oncogenic role in colorectal cancer (CRC) growth and adaptive MEK inhibitor (MEKi) resistance. PDE4DIP upregulation is associated with poor prognosis in CRC patients and its knockdown impairs the growth of KRAS-mutant CRC cells by inhibiting the core RAS signaling pathway. Mechanistically, PDE4DIP promotes the degradation of the RAS GTPase-activating protein (RasGAP) neurofibromin (NF1) and reactivates the RAS/ERK pathway, leading to adaptive MEKi resistance in KRAS-mutant CRC.