Rat embryonic stem cells create new era in development of genetically manipulated rat models

Embryonic stem(ES) cells are isolated from theinner cell mass of a blastocyst, and are used for the generation of gene-modified animals. In mice, the transplantation of gene-modified ES cells into recipient blastocysts leads to the creation of gene-targeted mice such as knock-in and knock-out mice; these gene-targeted mice contribute greatly to scientific development. Although the rat is considered a useful laboratory animal alongside the mouse, fewer genemodified rats have been produced due to the lack of robust establishment methods for rat ES cells. A new method for establishing rat ES cells using signaling inhibitors was reported in 2008. By considering the characteristics of rat ES cells, recent research has made progress in improving conditions for the stable culture of rat ES cells in order to generate gene-modified rats efficiently. In this review, we summarize several advanced methods to maintain rat ES cells and generate gene-targeted rats.

MicroRNA and liver cancer

Hepatocellular carcinoma(HCC)is a major cause of cancer-related deaths worldwide.HCC is characterized by a poor prognosis and an ever increasing number of scientific studies aim to find new diagnostic,prognostic,and therapeutic targets.MicroRNAs(miRNAs),small non-coding RNAs that regulate the gene expression in many processes,have been shown to play a crucial role in regulating hepatocellular carcinoma.miRNAs may act as oncogenic miRNAs and tumor suppressor miRNAs and regulate cancer cell proliferation,invasion,and metastasis by being differently upregulated or downregulated and targeting the genes related with carcinogenesis.miRNAs secreted from cancer cells are found circulating in the blood,presenting an opportunity for their use as diseaserelated biomarkers.Moreover,extracellular vesicle-derived miRNAs are known to reflect the cell of origin and function and may provide effective biomarkers for predicting diagnosis and prognosis and new therapeutic target in HCC.In this article,we describe the most recent findings regarding the molecular mechanisms and gene regulation of microRNA in HCC,as well as their application in diagnosis/prognosis and treatment.