A recurrently amplified long noncoding RNA in colorectal cancer regulates p53 protein stability through GRWD1/RPL11/MDM2 axis [RNA-seq]

By integrating genome-wide copy number alteration, RNA-seq and proteomics data from 589 colorectal cancer (CRC) patients, we revealed that chromosome 8q24.21 amplification is negatively correlated with p53 protein stability. Using siRNA and CRISPR activation screening, we pinpointed a novel long noncoding gene (PiHL, P53 inHibiting LncRNA) from 8q24.21 as a p53 negative regulator. PiHL is drastically upregulated in CRC and is an independent predictor of CRC poor prognosis. Further In vitro and In vivo models demonstrate that PiHL is crucial in maintaining cell proliferation and inhibiting cell apoptosis through a p53-depedent manner. Mechanistically, PiHL acts to promote p53 ubiquitination by sequestering RPL11 from MDM2, through enhancing GRWD1 and RPL11 complex formation. We further show that p53 can form a feedback loop with PiHL by directly binding to PiHL promoter and regulating its expression. Our study successfully illustrates how cancer cells hijack the PiHL-p53 axis to promote CRC progression and suggests PiHL as a potential therapeutic target in human CRCs. We examined gene expression changes in siRNA-NC and siRNA-PiHL treated HCT116 cells using RNA sequencing.