Emerging evidence indicate that the miR-17-92 cluster may have a causal role in breast cancer tumorigenesis as a novel class of oncogenes, but the role of these miRNAs in breast cancer invasion and migration remains unexplored.
Taken together with previous reports that miR-17-92 inhibits apoptosis by suppressing Pten via the miR-19 components, our results indicate that this miRNA cluster promotes tumorigenesis by antagonizing both tumor-suppressing mechanisms, apoptosis, and senescence, through the activities of different miRNA components encoded in this cluster.
In order to investigate whether there are similar patterns of miR-17-92 expression during embryogenesis and carcinogenesis, we have preformed a systematic study of the expression in cultured carcinoma cells, cultured primary human keratinocytes (KC), and during development of some murine tissues.
The miR-17-92 cluster encodes 7 miRNAs inside a single polycistronic transcript, and is known as a group of oncogenic miRNAs that contribute to tumorigenesis in several cancers.
The prognostic implications of miR-21, miR-17-92 and miR-155 were evaluated in diffuse large B-cell lymphoma (DLBCL) patients, and novel mechanism by which miR-21 contributes to the oncogenesis of DLBCL by regulating FOXO1 and PI3K/AKT/mTOR pathway was investigated.
The mir-17-92 cluster consists of six mature miRNAs and is implicated in diverse human cancers by targeting mRNAs involved in distinct pathways that either promote or inhibit carcinogenesis.
MicroRNA-93, derived from a paralog (miR-106b-25) of the miR-17-92 cluster, is involved in the tumorigenesis and progression of many cancers such as breast, colorectal, hepatocellular, lung, ovarian, and pancreatic cancer.
In conclusion, the role of miR-17-92 in USSCs may provide a better understanding of its function in tumorigenesis and for the possible use in cell therapy of the anti-mir-17-92 cluster.
Considering the growing interest in the field of miR‑17‑92 research, we herein review recent advances in the expression and regulation of this cluster in various cancer cells, discuss the proposed mechanism of action for tumorigenesis and tumor development, and propose clinical and therapeutic applications for miR‑17‑92 cluster members, such as potential cancer biomarkers.
Our results suggest that the miR-17-92 miRNAs promote tumorigenesis not only by repression of key regulators, but also by posttranscriptional increases of global gene expression.