The RNA-binding protein PNO1 is critical for ribosome biogenesis, but its potential role in cancer remains unknown. In this study, online data mining, cDNA, and tissue microarrays indicated that PNO1 expression was higher in colorectal cancer tissue than in noncancerous tissue, and its overexpression was associated with worse patient survival. Gain-offunction and loss-of-function studies demonstrated that PNO1 knockdown suppressed growth of colorectal cancer cells in vitro and in vivo, while PNO1 overexpression promoted colorectal cancer cell proliferation in vitro. In colorectal cancer cells expressing wild-type p53, PNO1 knockdown enhanced expression of p53 and its downstream gene p21, and reduced cell viability; these effects were prevented by p53 knockout and attenuated by the p53 inhibitor PFT-a. Moreover, PNO1 knockdown in HCT116 cells decreased levels of 18S rRNA, of 40S and 60S ribosomal subunits, and of the 80S ribosome. It also reduced global protein synthesis, increasing nuclear stress and inhibiting MDM2-mediated ubiquitination and p53 degradation. Overexpressing EBF1 suppressed PNO1 promoter activity and decreased PNO1 mRNA and protein, inhibiting cell proliferation and inducing cell apoptosis through the p53/p21 pathway. In colorectal cancer tissues, the expression of EBF1 correlated inversely with PNO1. Data mining of online breast and lung cancer databases showed increased PNO1 expression and association with poor patient survival; PNO1 knockdown reduced cell viability of cultured breast and lung cancer cells. Taken together, these findings indicate that PNO1 is overexpressed in colorectal cancer and correlates with poor patient survival, and that PNO1 exerts oncogenic effects, at least, in part, by altering ribosome biogenesis.Significance: This study identifies the ribosome assembly factor PNO1 as a potential oncogene involved in tumor growth and progression of colorectal cancer.

Purpose: Circulating tumor DNA (ctDNA) provides a novel approach for detecting tumor burden and predicting clinical outcomes of hepatocellular carcinoma (HCC). Here, we performed a thorough evaluation of HCC circulating genetic features and further fully integrated them to build a robust strategy for HCC monitoring and prognostic outcome assessment. Experimental Design: We performed target sequencing and low-coverage whole-genome sequencing on plasma samples collected from 34 long-term follow-up patients with HCC to capture tumor somatic SNVs and CNVs, respectively. Clinical information was also obtained to evaluate the prognostic performance of ctDNA comparing with clinically applied protein biomarkers. Results: All plasma samples before surgery showed somatic genetic variations resembling corresponding tumor tissues. During follow-up, SNVs and CNVs dynamically changed correlating to patients' tumor burden. We integrated the comprehensive ctDNA mutation profiles to provide a robust strategy to accurately assess patients' tumor burden with high consistence comparing with imaging results. This strategy could discover tumor occurrence in advance of imaging for an average of 4.6 months, and showed superior performance than serum biomarkers AFP, AFP-L3%, and Des-Gamma-Carboxy Prothrombin (DCP). Furthermore, our strategy could precisely detect minimal residual disease (MRD) in advance and predict patients' prognostic outcomes for both relapsefree survival (P ¼ 0.001) and overall survival (P ¼ 0.001); further combining ctDNA with DCP could increase the sensitivity for MRD detection. Conclusions: We demonstrated that plasma CNV and SNV levels dynamically correlated with patients' tumor burden in HCC. Our strategy of comprehensive mutation profile integration could accurately and better evaluate patients' prognostic risk and detect tumor occurrence in advance than traditional strategies.

Circular RNA (circRNA) can participate in various biological processes, including tumorigenesis, through their microRNA response elements. Alterations in circRNA profiles during hepatocellular carcinoma (HCC) progression and their clinical significance remain unclear. Here, we present extensive analysis of circRNA profiles in tumor and matched peritumor tissues collected from 10 HCC patients, conducted to identify circRNA related to HCC progression. A total of 42 dysregulated circRNA (38 down‐regulated and 4 up‐regulated) were identified in HCC tumor tissues compared with matched peritumor tissues, revealing the heterogeneity of circRNA profiles in HCC. CircADAMTS13, derived from Exon 13–14 of the ADAMTS13 gene, was significantly downregulated in HCC tumor tissues. Furthermore, clinicopathological analysis revealed that up‐regulation of circADAMTS13 was negatively associated with tumor size but positively associated with prognosis. In addition, overexpression of circADAMTS13 could markedly inhibit HCC cell proliferation in vitro. Bioinformatic analysis and luciferase reporter assays further revealed that circADAMTS13 directly interacts with microRNA (miR)‐484. Rescue experiments showed that miR‐484 mimics can reverse the tumor‐suppressing roles of circADAMTS13 in HCC. Therefore, our results demonstrated that circADAMTS13 can serve as a tumor suppressor during HCC progression via the functional pathway of sponging miR‐484.