Adenosine-to-inosine (A-to-I) RNA editing, a process mediated by adenosine deaminases that act on the RNA (ADAR) gene family, is a recently discovered epigenetic modification dysregulated in human cancers. However, the clinical significance and the functional role of RNA editing in colorectal cancer (CRC) remain unclear. We have systematically and comprehensively investigated the significance of the expression status of ADAR1 and of the RNA editing levels of antizyme inhibitor 1 (AZIN1 ), one of the most frequently edited genes in cancers, in 392 colorectal tissues from multiple independent CRC patient cohorts. Both ADAR1 expression and AZIN1 RNA editing levels were significantly elevated in CRC tissues when compared with corresponding normal mucosa. High levels of AZIN1 RNA editing emerged as a prognostic factor for overall survival and disease-free survival and were an independent risk factor for lymph node and distant metastasis. Furthermore, elevated AZIN1 editing identified high-risk stage II CRC patients. Mechanistically, edited AZIN1 enhances stemness and appears to drive the metastatic processes. We have demonstrated that edited AZIN1 functions as an oncogene and a potential therapeutic target in CRC. Moreover, AZIN1 RNA editing status could be used as a clinically relevant prognostic indicator in CRC patients.

Brain-derived neutrophic factor (BDNF) is a member of the neutrophin family that is known to activate the high-affinity tropomyosin-related receptor kinase B (TrkB). This study aimed to clarify the clinical and biological significance of the BDNF/TrkB pathway in gastric cancer. We analysed BDNF and TrkB expression in gastric cancer samples by real-time reverse transcription PCR and immunohistochemistry. To investigate the biological role of BDNF/TrkB axis, recombinant human BDNF (rhBDNF) and the Trk antagonist K252a were used for in vitro and in vivo analysis. The BDNF expression at the invasive front of primary tumours was significantly elevated compared with that in the tumour core and adjacent normal mucosa. Increased BDNF expression at the invasive front was significantly correlated with factors reflecting disease progression, and poor prognosis. Increased co-expression of the BDNF/TrkB axis was significantly correlated with poor prognosis. Gastric cancer cells expressed BDNF, and administration of rhBDNF promoted proliferation, migration, invasion, and inhibition of anoikis. These effects were generally inhibited by K252a. In an in vivo assay, BDNF(+)/TrkB(+) gastric cancer cells injected into nude mice established peritoneal dissemination, whereas K252a inhibited tumour growth. The BDNF/TrkB pathway might be deeply involved in gastric cancer disease progression.

Objective To investigate the function of a novel primate-specific long non-coding RNA (lncRNA), named FLANC, based on its genomic location (co-localised with a pyknon motif), and to characterise its potential as a biomarker and therapeutic target. Design FLANC expression was analysed in 349 tumours from four cohorts and correlated to clinical data. In a series of multiple in vitro and in vivo models and molecular analyses, we characterised the fundamental biological roles of this lncRNA. We further explored the therapeutic potential of targeting FLANC in a mouse model of colorectal cancer (CRC) metastases. Results FLANC, a primate-specific lncRNA feebly expressed in normal colon cells, was significantly upregulated in cancer cells compared with normal colon samples in two independent cohorts. High levels of FLANC were associated with poor survival in two additional independent CRC patient cohorts. Both in vitro and in vivo experiments demonstrated that the modulation of FLANC expression influenced cellular growth, apoptosis, migration, angiogenesis and metastases formation ability of CRC cells. In vivo pharmacological targeting of FLANC by administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with a specific small interfering RNA, induced significant decrease in metastases, without evident tissue toxicity or pro-inflammatory effects. Mechanistically, FLANC upregulated and prolonged the half-life of phosphorylated STAT3, inducing the overexpression of VEGFA, a key regulator of angiogenesis. Conclusions Based on our findings, we discovered, FLANC as a novel primate-specific lncRNA that is highly upregulated in CRC cells and regulates metastases formation. Targeting primate-specific transcripts such as FLANC may represent a novel and low toxic therapeutic strategy for the treatment of patients.