ARTEMIN Promotes Oncogenicity and Resistance to 5-Fluorouracil in Colorectal Carcinoma by p44/42 MAPK Dependent Expression of CDH2.

ARTEMIN (ARTN), one of the glial-cell derived neurotrophic factor family of ligands, has been reported to be associated with a number of human malignancies. In this study, the enhanced expression of ARTN in colorectal carcinoma (CRC) was observed; the expression of ARTN positively correlated with lymph node metastases and advanced tumor stages and predicted poor prognosis. Forced expression of ARTN in CRC cells enhanced oncogenic behavior, mesenchymal phenotype, stem cell-like properties and tumor growth and metastasis in a xenograft model. These functions were conversely inhibited by depletion of endogenous ARTN. Forced expression of ARTN reduced the sensitivity of CRC cells to 5-FU treatment; and 5-FU resistant CRC cells harbored enhanced expression of ARTN. The oncogenic functions of ARTN were demonstrated to be mediated by p44/42 MAP kinase dependent expression of CDH2 (CADHERIN 2, also known as N-CADHERIN). Inhibition of p44/42 MAP kinase activity or siRNA mediated depletion of endogenous CDH2 reduced the enhanced oncogenicity and chemoresistance consequent to forced expression of ARTN induced cell functions; and forced expression of CDH2 rescued the reduced mesenchymal properties and resistance to 5-FU after ARTN depletion. In conclusion, ARTN may be of prognostic and theranostic utility in CRC.

Autocrine hGH stimulates oncogenicity, epithelial-mesenchymal transition and cancer stem cell-like behavior in human colorectal carcinoma.

Tumor derived human growth hormone (hGH) has been implicated in cancer development and progression. However, the specific functional role of autocrine/paracrine hGH in colorectal cancer (CRC) remains largely to be determined. Herein, we demonstrated a crucial oncogenic role of autocrine hGH in CRC progression. Elevated hGH expression was detected in CRC compared to normal colorectal tissue, and hGH expression in CRC was positively associated with tumor size and lymph node metastasis. Forced expression of hGH stimulated cell proliferation, survival, oncogenicity and epithelial to mesenchymal transition (EMT) of CRC cells, and promoted xenograft growth and local invasion in vivo. Autocrine hGH expression in CRC cells stimulated the activation of the ERK1/2 pathway, which in turn resulted in increased transcription of the mesenchymal marker FIBRONECTIN 1 and transcriptional repression of the epithelial marker E-CADHERIN. The autocrine hGH-stimulated increase in CRC cell proliferation, cell survival and EMT was abrogated upon ERK1/2 inhibition. Furthermore, autocrine hGH-stimulated CRC cell migration and invasion was dependent on the ERK1/2-mediated increase in FIBRONECTIN 1 expression and decrease in E-CADHERIN expression. Forced expression of hGH also enhanced CSC-like behavior of CRC cells, as characterized by increased colonosphere formation, ALDH-positive population and CSC marker expression. Autocrine hGH-enhanced cancer stem cell (CSC)-like behavior in CRC cells was also observed to be E-CADHERIN-dependent. Thus, autocrine hGH plays a critical role in CRC progression, and inhibition of hGH could be a promising targeted therapeutic approach to limit disease progression in metastatic CRC patients.

Recurrently deregulated lncRNAs in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) cells often invade the portal venous system and subsequently develop into portal vein tumour thrombosis (PVTT). Long noncoding RNAs (lncRNAs) have been associated with HCC, but a comprehensive analysis of their specific association with HCC metastasis has not been conducted. Here, by analysing 60 clinical samples' RNA-seq data from 20 HCC patients, we have identified and characterized 8,603 candidate lncRNAs. The expression patterns of 917 recurrently deregulated lncRNAs are correlated with clinical data in a TCGA cohort and published liver cancer data. Matched array data from the 60 samples show that copy number variations (CNVs) and alterations in DNA methylation contribute to the observed recurrent deregulation of 235 lncRNAs. Many recurrently deregulated lncRNAs are enriched in co-expressed clusters of genes related to cell adhesion, immune response and metabolic processes. Candidate lncRNAs related to metastasis, such as HAND2-AS1, were further validated using RNAi-based loss-of-function assays. Thus, we provide a valuable resource of functional lncRNAs and biomarkers associated with HCC tumorigenesis and metastasis.

CCAR1 5' UTR as a natural miRancer of miR-1254 overrides tamoxifen resistance.

MicroRNAs (miRNAs) typically bind to unstructured miRNA-binding sites in target RNAs, leading to a mutual repression of expression. Here, we report that miR-1254 interacts with structured elements in cell cycle and apoptosis regulator 1 (CCAR1) 5' untranslated region (UTR) and this interaction enhances the stability of both molecules. miR-1254 can also act as a repressor when binding to unstructured sites in its targets. Interestingly, structured miR-1254-targeting sites act as both a functional RNA motif-sensing unit, and an independent RNA functional unit that enhances miR-1254 expression. Artificially designed miRNA enhancers, termed "miRancers", can stabilize and enhance the activity of miRNAs of interest. We further demonstrate that CCAR1 5' UTR as a natural miRancer of endogenous miR-1254 re-sensitizes tamoxifen-resistant breast cancer cells to tamoxifen. Thus, our study presents a novel model of miRNA function, wherein highly structured miRancer-like motif-containing RNA fragments or miRancer molecules specifically interact with miRNAs, leading to reciprocal stabilization.