Ahmed Elgehama1, Jaceline Pires Sanches Sanches2, Lili Guerra3, Wei Yang2
1Stony Brook University, Renaissance School of Medicine, Stony Brook, NY,2Stony Brook University, Stony Brook, NY,3Stony Brook UNIVERSITY, Stony Brook, NY
摘要 Abstract
Background : Prostate cancer (PC) metastasis is the leading cause of PC-related mortality, yet effective therapies targeting this lethal process remain lacking. We previously identified RIPK2 as a promising drug target in PC metastasis, functioning in part through a noncanonical RIPK2/MKK7/c-Myc phosphorylation pathway ( Nat. Commun. , 2022). However, additional downstream effectors and upstream regulators of RIPK2 remain poorly characterized. This study aims to address this knowledge gap, which represents a major barrier to developing highly effective and low-toxicity combination therapies.
Methods: Genetic manipulation was performed using CRISPR/Cas9 knockout, siRNA knockdown, and overexpression of wild-type or mutant genes. The metastatic potential of PC cells was assessed by cell proliferation, Matrigel invasion, clonogenicity, and soft-agar assays. RIPK2 activation of CDK2 was evaluated by western blotting and in vitro kinase assays. RIPK2-CDK2 interaction was examined using co-immunoprecipitation, GST pulldown, proximity-ligation assay, fluorescence colocalization, and fluorescence resonance energy transfer. Gene transcription and expression were measured by RT-qPCR. Protein stability was determined using cycloheximide chase and ubiquitination assays. Synergistic effects of RIPK2 and CDK2 inhibitors are assessed with a 6x6 matrix. At least two independent cell lines were used for each cell assay.
Results: RIPK2 enhanced the metastatic potential of PC 22Rv1 and PC3 cells primarily through its kinase activity, cytoplasmic localization, and induction of c-Myc expression. RIPK2 bound directly to CDK2 and activated it, leading to phosphorylation of c-Myc at S62. Notably, active CDK2 increased both transcription and protein stability of RIPK2, establishing a positive feedback loop. Co-inhibition of RIPK2 and CDK2 synergistically reduced c-Myc protein levels and suppressed PC cell invasion and colony formation.
Conclusion: RIPK2 and CDK2 form a multi-layered positive feedback loop that sustains c-Myc expression and drives PC metastatic progression. Low-dose co-inhibition of these two kinases using clinically evaluated inhibitors represents a promising therapeutic strategy to overcome c-Myc-dependent PC metastasis with high efficacy and minimal toxicity.