The RNA‐guided nuclease CRISPR‐Cas9 (clustered regularly interspaced short palindromic repeats‐CRISPR associated nuclease 9) and its variants such as nickase Cas9, dead Cas9, guide RNA scaffolds and RNA‐targeting Cas9 are convenient and versatile platforms for site‐specific genome editing and epigenome modulation. They are easy‐to‐use, simple‐to‐design and capable of targeting multiple loci simultaneously. Given that cancer develops from cumulative genetic and epigenetic alterations, CRISPR‐Cas9 and its variants (hereafter referred to as CRISPR‐Cas9 systems) hold extensive application potentials in cancer modeling and therapy. To date, they have already been applied to model oncogenic mutations in cell lines (e.g., Choi and Meyerson, Nat Commun 2014;5:3728) and in adult animals (e.g., Xue et al., Nature 2014;514:380–4), as well as to combat cancer by disabling oncogenic viruses (e.g., Hu et al., Biomed Res Int 2014;2014:612823) or by manipulating cancer genome (e.g., Liu et al., Nat Commun 2014;5:5393). Given the importance of epigenome and transcriptome in tumourigenesis, manipulation of cancer epigenome and transcriptome for cancer modeling and therapy is a promising area in the future. Whereas (epi)genetic modifications of cancer microenvironment with CRISPR‐Cas9 systems for therapeutic purposes represent another promising area in cancer research. Herein, we introduce the functions and mechanisms of CRISPR‐Cas9 systems in genome editing and epigenome modulation, retrospect their applications in cancer modelling and therapy, discuss limitations and possible solutions and propose future directions, in hope of providing concise and enlightening information for readers interested in this area.

Osteosarcoma is recognized as a malignant tumor in the skeletal system. Long non-coding RNAs (lncRNAs) have been exhibited to play crucial roles in osteosarcoma development. Our current study focused on the biological effects and mechanism of LINC00968 in osteosarcoma pathogenesis. We observed that LINC00968 was dramatically elevated in osteosarcoma cells including U2OS, MG63, Saos-2, SW1353, and 143-B cells compared to human osteoblast cell line hFOB. Silence of LINC00968 inhibited osteosarcoma cell growth and proliferation in vitro. Reversely, overexpression of LINC00968 promoted osteosarcoma cell survival and cell colony formation ability in Saos-2 and 143-B cells. In addition, LINC00968 was able to induce osteosarcoma cell migration and invasion through up-regulating MMP-2 and MMP-9 protein levels. The phosphoinosmde-3-kinase/Protein Kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway has been reported to participate in several cancer types. Here, in our study, we found that PI3K/AKT/mTOR pathway was involved in osteosarcoma progression. Knockdown of LINC00968 inactivated PI3K/AKT/mTOR signaling pathway in vitro. Subsequently, in vivo tumor xenografts were established using 143-B cells to investigate whether LINC00968 can induce osteosarcoma development in vivo. Consistently, it was indicated that inhibition of LINC00968 significantly inhibited osteosarcoma progression in vivo. Taken these together, in our research, LINC00968 could be provided as a novel prognostic biomarker and therapeutic target in osteosarcoma diagnosis and treatment.

Our data provide new insights for the involvement of miR-191 in osteosarcoma and suggest that the increased expression of miR-191 may be associated with aggressive tumor progression and adverse outcome. Of note, serum miR-191 quantification may be a promising biomarker for the diagnosis and prognosis in osteosarcoma.