Colorectal cancer is one of the leading causes of cancer-related mortality worldwide. Cancer stem cells are cell populations with stem cell nature presenting in tumor tissues and are the root of tumor formation and metastasis. CCND1 and E2F3 play important roles in cell cycle regulation. The 3'UTRs of CCND1 and E2F3 contain miR-449 binding sites. By transfecting pre-miR-449b and inhibiting miR-449b, we found that cell cycle, cell proliferation ability and cell cycle regulatory protein expression levels of colon cancer stem cells were altered. The correlation between CCND1, E2F3 and miR-449b showed that miR-449b could downregulate CCND1 and E2F3 expression. This, in turn, reduced the proliferative ability of colon cancer stem cells. These data suggest that miR-449b plays a tumor-suppressive role in colon cancer stem cells.

The present study aimed to identify microRNA (miRNA) expression profiles associated with brain metastases of colorectal cancers. We conducted miRNA expression profiling of 3 primary colorectal cancers and 3 brain-metastatic carcinomas using Agilent Human miRNA Microarrays. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) was employed to validate the results obtained from the miRNA microarray analysis. Overexpression of miR-145, miR-1, miR-146a, miR-576-5p, miR-126*, HS287, miR-28-5p, miR-143, miR-199b-5p, miR-199a-5p, miR-10b, miR-22, miR-133b, miR-145*, miR-199a, miR-133a, miR-125b and downregulation of miR-31 and HS170 were observed in brain-metastatic carcinomas. Quantitative RT-PCR experiments with miR-125b confirmed the expression patterns we found in our microarray experiments. miRNAs are differentially expressed between colorectal cancers and matched brain-metastatic carcinomas. The miRNA variation trend is quite different in the process of metastasis compared to that of carcinogenesis. These miRNAs may therefore serve as potential diagnostic markers and therapeutic targets for colorectal cancers with brain metastases.

Colorectal cancer (CRC) is the third most common malignant tumor worldwide, affecting over 1.23 million individuals annually. Over the past several years, the role of microRNAs (miRNAs) in CRC cells have been extensively investigated. Recently, it was discovered that extracellular miRNAs circulate in the blood of healthy individuals as well as CRC patients. Serum circulating miRNAs as novel biomarkers may be a new approach to CRC diagnosis. However, their secretory mechanism and biological function have not been fully elucidated. In this review, the main serum miRNAs used as potential diagnostic biomarkers for CRC, such as miR‑92, miR‑141, miR‑29a, miR‑21, miR‑221, miR‑601 and miR‑760, were summarized. In addition, the mechanism of miRNA secretion from CRC cells was discussed. It is recommended that additional studies focus on the usefulness of serum miRNAs for early CRC diagnosis, prognosis and therapeutics.

Interleukin (IL)‑13 is an immunoregulatory cytokine secreted by numerous immune cells. Its functions are similar to those of IL‑4 and they share a common receptor. This cytokine has been included in recent studies on human tumors and malignant diseases, evoking a scientific interest to investigate the role of IL‑13 and its receptors as novel biomarkers and targets for therapy. Colorectal cancer is one of the most common human malignancies, its prognosis is not promising and the efficacy of molecular‑targeted therapy has not been established. This review summarizes the currently available data on the role of IL‑13 and its receptors in colorectal cancer, including the signaling pathways involved in mediating the effects of IL‑13, the role of IL‑13 and/or its receptors in the prediction of cancer and several drugs targeting IL‑13 or its receptors that are currently under evaluation.