5-Fluorouracil (5-FU) is one of the most effective drugs for the treatment of colorectal cancer (CRC). However, there is an urgent need in reducing its systemic side effects and chemoresistance to make 5-FU-based chemotherapy more effective and less toxic in the treatment of CRC. Here, enalapril, a clinically widely used antihypertensive and anti-heart failure drug, has been verified as a chemosensitizer that extremely improves the sensitivity of CRC cells to 5-FU. Enalapril greatly augmented the cytotoxicity of 5-FU on the cell growth in both established and primary CRC cells. The combination of enalapril and 5-FU synergistically suppressed the cell migration and invasion in both 5-FU-sensitive and -resistant CRC cells in vitro, and inhibited angiogenesis, tumor growth, and metastasis of 5-FU-resistant CRC cells in vivo without increased systemic toxicity at concentrations that were ineffective as individual agents. Furthermore, combined treatment cooperatively inhibited NF-κB/STAT3 signaling pathway and subsequently reduced the expression levels of NF-κB/STAT3-regulated proteins (c-Myc, Cyclin D1, MMP-9, MMP-2, VEGF, Bcl-2, and XIAP) in vitro and in vivo. This study provides the first evidence that enalapril greatly sensitized CRC cells to 5-FU at clinically achievable concentrations without additional toxicity and the synergistic effect may be mainly by cooperatively suppressing proliferation, angiogenesis, and NF-κB/STAT3-regulated proteins.

Chemoresistance to 5-fluorouracil (5-Fu)-based chemotherapy is a leading obstacle in achieving effective treatment for colorectal cancer (CRC). Typically, NF-κB activation induced by the chemotherapeutics themselves is an important cause resulting in chemoresistance. Specifically, NF-κB activation can inhibit tumor cell apoptosis and induce chemoresistance. Drugs that can prevent NF-κB activation induced by chemotherapeutics are urgently needed to overcome chemoresistance. Obviously, aspirin is one of these agents, which has been demonstrated to possess antitumor activities and as an inhibitor of NF-κB. The current study aimed to investigate whether aspirin was able to overcome the chemoresistance to 5-Fu in CRC, together with the potential synergistic mechanisms. Our results suggested that aspirin remarkably potentiated the inhibitory effect of 5-Fu on the growth and invasion of resistant cells in vitro. In vivo, aspirin markedly enhanced the antitumor activity of 5-Fu in suppressing tumor growth and metastasis, and down-regulating the expression of NF-κB-regulated genes in the 5-Fu-resistant cells. Obviously, aspirin completely eradicated the 5-Fu-induced NF-κB activation, without inducing pronounced adverse effects. Taken together, findings in this study suggest that aspirin can reverse chemoresistance and potentiate the antitumor effect of 5-Fu, which is achieved through abolishing the 5-Fu-induced NF-κB activation, suggesting that aspirin may be a promising adjuvant therapeutic agent for CRC.

BACKGROUND: The accurate Tumor-Node-Metastasis (TNM) staging of colorectal cancer (CRC) is of great guiding significance for the judgment of tumor progression and prognosis, and the formulation of treatment strategies. OBJECTIVE: The aim of this study was to construct a recurrence risk scoring (RRS) system and prognostic prediction model to improve the accuracy of staging, prognosis prediction, and clinical decision making in resectable CRC. METHODS: CRC patients who underwent radical resection were retrospectively enrolled into study. Multivariable Cox regression model was applied to screen for independent prognostic factors. The RRS system is composed of independent prognostic factors which was awarded 1point each. A prognostic model composed of RRS and TNM staging system (RRS-TNM model) was applied to predict postoperative recurrence. RESULTS: TNM stage, tumor differentiation, preoperative elevated Carcinoembryonic Antigen, Carbohydrate Antigen 199, Prothrombin Time and Fibrinogen were the independent prognostic biomarkers. 173 of 540 patients had recurrence. The 5-year cumulative recurrence rate (5-y CRR) and disease-free survival (DFS) of postoperative p-TNM stage I, II, and III were 12.7% and 104.8 months, 26.5% and 89.3 months, and 55.5% and 57.3 months, respectively. The 5-y CRR and DFS of preoperative Low-risk (RRS 0-1score), Middle-risk (RRS 2-3scores), and High-risk (RRS 4-5scores) groups were 13.9% and 101.1 months, 40.9% and 75.5 months, and 70.2% and 41.1 months. The AUC (area under ROC curve) of RRS system was not inferior to that of TNM staging system (0.713 vs. 0.666; P= 0.093). The AUC (0.770) and C-index value (0.721) of RRS-TNM model were significantly better than both RRS and TNM staging system (P< 0.001). CONCLUSIONS: The RRS system accurately identifies CRC patients with high-risk recurrence preoperatively. Constructing a nomogram using the RRS system and TNM staging significantly improves the accuracy of staging and prognosis prediction, which is of great clinical significance for individualized clinical treatment and follow-up of CRC.

Accurately quantifying the expression of individual isoforms remains a formidable challenge, especially in contexts like neurodegenerative diseases and cancers, which are noted for their high isoform diversity. The first contribution of the present study is the development of a new method, named differential splicing frequency analysis (DSFA), which enables more sensitive capture of the alternative splicing information in RNA-seq data. DSFA quantifies the expression levels of splicing junctions, rather than those of genes, isoforms or exons. Application of DSFA to the analysis of Alzheimer's disease (AD)-associated genes resulted in the identification of APP/58417N and APP/52804N as differentially expressed splicing junctions in human and mouse, respectively. Observed in a considerable portion of the re-analyzed RNA-seq datasets, the splicing frequencies of APP/58417N and APP/52804N were significantly decreased in AD groups. Such reductions in splicing frequencies lead to decreased production of secretory APP proteins, potentially playing a critical role in AD onset or progression. The present study has proposed over-expression of U1 snRNA as an effective method for modulating the splicing frequencies of splicing junctions, thereby rapidly establishing cellular or animal AD models. Therefore, the present study has provided new methods, preliminary results, and valuable insights, advancing the understanding of the functions of U1 snRNA and the roles of alternative splicing in its associated diseases.