IGF2BP3 binds to FBXO32 to activate the cyclic guanosine monophosphate-protein kinase G pathway, promoting gastric cancer progression

Background: N⁶-methyladenosine (m⁶A) exerts a pro-carcinogenic effect in diverse cancers. The relationship between m⁶A-reading protein IGF2BP3 and gastric Cancer (GC) has not yet been fully elucidated.

Aim: To investigate the molecular mechanisms of IGF2BP3 in GC carcinogenesis and progression and thus provide a rationale for novel therapeutic strategies.

Methods: Expression levels of IGF2BP3 in GC were determined using quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot (WB), and immunohistochemistry, and their associations with patients' clinicopathological characteristics were analyzed. The role of IGF2BP3 in GC was investigated using cellular functional assays and subcutaneous xenograft models, and its downstream targets and signaling pathways were identified using high-throughput Sequencing, bioinformatics analysis, RNA immunoprecipitation qPCR, dual luciferase reporter assay, qRT-PCR, and WB. The mechanism of IGF2BP3 in GC was validated via WB and rescue and inhibition experiments.

Results: IGF2BP3 was highly expressed in GC and associated with diffuse-type GC, incidence of lymph node metastasis, advanced tumor node metastasis stage, and deeper tumor invasion depth. In vitro experiments demonstrated that IGF2BP3 promoted proliferation, migration, and invasiveness of GC cells, while inhibiting Apoptosis and augmenting intracellular levels of glucose metabolism. In vivo experiments revealed that IGF2BP3 contributes to the growth of GC. Mechanistically, IGF2BP3 recognized and bound to the m⁶A site at position 1427 on FBXO32 messenger RNA, thereby increasing protein expression of FBXO32, and further activated the downstream cyclic guanosine monophosphate-protein kinase G (cGMP-PKG) signaling pathway to modulate various biological functions of GC cells and promote progression of GC. Furthermore, treatment with a selective PKG Inhibitor KT5823 significantly suppressed the proliferative capacity of GC cells.

Conclusion: IGF2BP3 increases FBXO32 protein expression in an m⁶A-dependent manner, activates the cGMP-PKG signaling pathway, and promotes GC progression. Targeting of the IGF2BP3/FBXO32/cGMP-PKG axis could thus represent a promising therapeutic modality for GC.

Cyclic guanosine monophosphate-protein kinase G; FBXO32; Gastric cancer; IGF2BP3; N6-methyladenosine.