We previously demonstrated that long non-coding RNA cytoskeleton regulator RNA (CYTOR), also known as Linc00152, was significantly overexpressed in colon cancer and conferred resistance to oxaliplatin-induced apoptosis. At the same time, elevated CYTOR expression was also reported in gastric cancer and exerted influences on epithelial-mesenchymal transition (EMT) markers. However, the precise mechanism by which CYTOR promotes the EMT phenotype and cancer metastasis remains poorly understood. Here, we showed that loss of epithelial characteristics and simultaneous gain of mesenchymal features correlated with CYTOR expression. Knockdown of CYTOR attenuated colon cancer cell migration and invasion. Conversely, ectopic expression of CYTOR induced an EMT program and enhanced metastatic properties of colon cancer cells. Mechanistically, the binding of CYTOR to cytoplasmic β-catenin impeded casein kinase 1 (CK1)-induced β-catenin phosphorylation that enabled it to accumulate and translocate to the nucleus. Reciprocally, β-catenin/TCF complex enhanced the transcription activity of CYTOR in nucleus, thus forming a positive feed-forward circuit. Moreover, elevated CYTOR, alone or combined with overexpression of nuclear β-catenin, was predictive of poor prognosis. Our findings suggest that CYTOR promotes colon cancer EMT and metastasis by interacting with β-catenin, and the positive feed-forward circuit of CYTOR-β-catenin might be a useful therapeutic target in antimetastatic strategy.

SIRT1, a NAD+ dependent class III deacetylase, takes part in many important biological processes. Previous studies show that SIRT1 is overexpressed in some cancers and plays an essential role in tumorigenesis. However, the association between SIRT1 and colorectal cancer (CRC) is still unclear. We found that many CRC specimens had strong SIRT1 expression, which had an obvious correlation with poor prognosis of CRC patients. Meanwhile, SIRT1 expression had a co-localization with CD133, a current universal marker to characterize colorectal cancer stem cells (CSCs). In vitro studies also revealed that SIRT1 was overexpressed in colorectal CSC-like cells. Moreover, SIRT1 deficiency decreased percentage of CD133+ cells, attenuated the abilities of colony and sphere formation, and inhibited tumorigenicity in vivo in CRC cells. Further study demonstrated that the expressions of several stemness-associated genes, including Oct4, Nanog, Cripto, Tert and Lin28, were reduced by SIRT1 knockdown in CRC cells. Taken together, our findings suggest that SIRT1 plays a crucial role in keeping the characteristics of CSCs cells. SIRT1 is a potential independent prognostic factor of CRC patients after tumor resection with curative intent, and will contribute to providing a promising new approach to target at CSCs in CRC treatment.

The inducible T-cell co-stimulator (ICOS) belongs to the B7-CD28 immunoglobulin superfamily, which is currently the subject of intense study due to great successes gained in treatment of different malignancies by disrupting their family members. However, the role of ICOS played in colorectal cancer (CRC) remains poorly understood. A tissue microarray (n = 310) was stained with the ICOS specific antibody and ICOS expression is decreased in patients with either lymphatic or distant metastasis and inversely associated with CEA level and TNM stage of CRC patients. Importantly, high ICOS expression is significantly correlated with overall survival (OS) of CRC patients (n = 230, p < 0.001), and ICOS expression is also proved to be an independent prognostic factor by multivariate analysis. Surgical excised CRC specimens (n = 26) were enzymatically digested to get the tumor-infiltrating leukocytes and ICOS is mainly expressed on CD4⁺ T cells and its ligand ICOSL is detected on macrophages and tumor cells. ICOS expression level is associated with increased cytotoxic T lymphocyte antigen (CTLA)-4 (p < 0.001) and programmed death (PD-1) (p = 0.005) expression on T cells and more infiltrated CD8⁺ T cells (p < 0.001). Interestingly, ICOS⁺CD4⁺ cells isolated from tumor tissues have high T-bet and interferon (IFN)γ expression, the characteristics of Th1 cells, compared to ICOS⁻CD4⁺ cells. In addition, the correlation between the percentage of ICOS⁺CD4⁺ T cells in tumor tissue and peripheral blood was detected. Conclusively, expression of ICOS is associated with improved survival in CRC and percentage of ICOS⁺CD4⁺ cells acting as Th1 cells in either primary tumor tissue or peripheral blood may be a clinical biomarker for good prognosis of CRC patients.

The abnormal expression of microRNAs (miRNAs) in colorectal cancer (CRC) progression has been widely investigated. It was reported that the same hairpin RNA structure could generate mature products from each strand, termed 5p and 3p, which binds different target mRNAs. Here, we explored the expression, functions, and mechanisms of miR-514b-3p and miR-514b-5p in CRC cells and tissues. We found that miR-514b-3p was significantly down-regulated in CRC samples, and the ratio of miR-514b-3p/miR-514b-5p increased from advanced CRC, early CRC to matched normal colorectal tissues. Follow-up functional experiments illustrated that miR-514b-3p and miR-514b-5p had distinct effects through interacting with different target genes: MiR-514b-3p reduced CRC cell migration, invasion and drug resistance through increasing epithelial marker and decreasing mesenchymal marker expressions, conversely, miR-514b-5p exerted its pro-metastatic properties in CRC by promoting EMT progression. MiR-514b-3p overexpressing CRC cells developed tumors more slowly in mice compared with control cells, however, miR-514b-5p accelerated tumor metastasis. Overall, our data indicated that though miR-514b-3p and miR-514b-5p were transcribed from the same RNA hairpin, each microRNA has distinct effect on CRC metastasis.

ATPase family AAA domain-containing 2 (ATAD2) has been identified as a critical modulator involved in cell proliferation and invasion. The purpose of this study was to explore the expression of ATAD2 in CRC tissues as well as its relationship with degree of malignancy. Data containing three independent investigations from Oncomine database demonstrated that ATAD2 is overexpressed in CRC compared with normal tissue, and similar result was also found in 32 pairs of CRC tissues by qPCR. The protein expression of ATAD2 was examined in six CRC cell lines and 300 CRC specimens. The results showed that high expression of ATAD2 was significantly correlated with tumor size(P<0.001), serum CEA(P=0.012), lymph node metastasis(P=0.018), liver metastasis(P=0.025), and clinical stage(P=0.004). Kaplan-Meier method suggested that higher ATAD2 protein expression significantly associated with the overall survival (OS) of CRC patients(P<0.001)and was an independent predictor of poor OS. Functional studies showed that suppression of ATAD2 expression with siRNA could significantly inhibit the growth in SW480 and HCT116 cells. These results indicated that ATAD2 could serve as a prognostic marker and a therapeutic target for CRC.