Background:Ribosome-binding protein 1 (RRBP1) has been implicated in the regulation of unfolded protein response, which is involved in almost every aspect of cancer development. We aimed to explore the significance of RRBP1 in the progression and prognosis of colorectal cancer (CRC).Methods:The study population consisted of 856 patients with stage I–III CRC from two hospitals. RRBP1 expression was examined by immunohistochemisty (IHC) in colorectal tissues. The correlation of RRBP1 expression and CRC occurrence was assessed in paired cancer-adjacent tissues. Factors contributing to prognosis were evaluated in a training-validation design with univariate and multivariate Cox analysis. Colorectal cancer aggressiveness caused by RRBP1 knockdown or overexpression was evaluated in CRC cells.Results:RRBP1 was aberrantly overexpressed in CRC. Compared with low-RRBP1 patients, high-RRBP1 patients had shorter disease-specific survival in the training (hazard ratio (HR), 2.423; 95% confidence interval (CI), 1.531–3.835) and validation cohorts (HR, 3.749; 95% CI, 2.166–6.448) in multivariate Cox analysis. High-RRBP1 independently predicted a shorter disease-free survival (HR, 4.821; 95% CI, 3.220–7.218) in the validation cohort. RRBP1 knockdown reduced the aggressiveness of CRC cells in vitro and inhibited the growth of CRC xenografts in vivo.Conclusions:High RRBP1 expression facilitates CRC progression and predicts an unfavourable post-operative prognosis.

BackgroundMicroRNAs (miRNAs) are small noncoding RNAs that potentially play a critical role in tumorigenesis. Mounting evidence indicates that one specific miRNA: miR-320b is down regulated in numerous human cancers, including colorectal cancer (CRC); making the hypothesis that miR-320b may play a key role in tumorigenesis plausible. However, its role in carcinogenesis remains poorly defined. The goal of this study is to better clarify the role of miR-320b in tumor growth of CRC.MethodsQuantitative reverse-transcription polymerase chain reaction (qRT-PCR) was conducted to detect the expression of miR-320b in CRC tissues and 5 CRC cell lines. The effect of miR-320b on cell proliferation was analyzed in vitro and in vivo. Furthermore, a luciferase reporter assay was performed to measure the target effects of miR-320b. Lastly, the messenger RNA (mRNA) and protein levels of the gene c-MYC were measured in CRC cell lines and tissues by qRT-PCR, and confirmed via Western blot and Immunohistochemical (IHC) staining.ResultsThe results presented here showed that miR-320b expression was down regulated in both CRC tissues and cells. Overexpression of miR-320b in CRC cells was statistically correlated with a decrease of cell growth in vitro and in vivo, while c-MYC was identified as a target gene of miR-320b in CRC. Furthermore, it was found that up-regulation of c-Myc can attenuate the effects induced by miR-320b.ConclusionsOur identification of c-MYC as a target gene of miR-320b provides new insights into the pathophysiology of CRC proliferation, and identifies miR-320b as a novel therapeutic target for the treatment of CRC.

Purpose Nicotinamide n‐methyltransferase (NNMT) has good biochemical activity and epigenetic regulation, and has been reported as a major metabolic regulator of cancer. The goal of this study was to investigate the significance of stromal NNMT expression in colorectal cancer (CRC). Patients and methods Stromal expression of NNMT in primary CRC, metastasis CRC, and their non‐cancerous tissues from 1088 CRC patients was examined by immunohistochemistry. The associations between stromal NNMT expression and survival outcomes in 967 patients with stage I‐III CRC were further evaluated with Kaplan‐Meier curve and Cox model analyses. Results NNMT expression was mainly sourced from stromal compartments and also elevated in CRC. Patients with high stromal NNMT (IHC‐score ≥ 106) have a worse survival than those patients with low stromal NNMT. In multiple Cox analyses, high expression of stromal NNMT remained as an independent risk factor in CRC for disease‐free survival with a hazard ratio (HR) of 1.415 (95% confidence interval [CI], 1.015‐1.972) and disease‐specific survival with a HR of 5.004 (95% CI, 2.301‐10.883). In addition, high stromal NNMT expression in CRC also indicates the poor survival outcomes in patients with early stage CRC (stage I and II) and in patients who undergo chemotherapy. Conclusion NNMT is mainly located in CRC stromal compartment. High stromal NNMT expression predicts an unfavorable postoperative prognosis.