Hsa-miR-665 Is a Promising Biomarker in Cancer Prognosis

SIMPLE SUMMARY: MicroRNAs (miRNAs) are small biomolecules that can indicate the presence of certain diseases, including cancer. They are stable and can be easily detected in blood and urine samples. Here we review the different roles of a specific miRNA, miR-665, in several cancer types and evaluate its potential as biomarker for early detection and prognosis concerning these cancer types. Considerable changes in miR-665 levels have been detected in several cancer types making miR-665 a good candidate biomarker for early detection of these cancers. However, miR-665 can be upregulated in one type of cancer and downregulated in another, and its levels can even change during the progression of the same cancer. Therefore, extrapolation between different cancer types is not advised and more clinical data are needed before miR-665 can be used as a biomarker for these cancers. A better knowledge of the functions of miR-665 will be valuable in improving early detection and treatment of cancer. ABSTRACT: Biomarkers are biomolecules used to identify or predict the presence of a specific disease or condition. They play an important role in early diagnosis and may be crucial for treatment. MicroRNAs (miRNAs), a group of small non-coding RNAs, are more and more regarded as promising biomarkers for several reasons. Dysregulation of miRNAs has been linked with development of several diseases, including many different types of cancer, and abnormal levels can be present in early stages of tumor development. Because miRNAs are stable molecules secreted and freely circulating in blood and urine, they can be sampled with little or no invasion. Here, we present an overview of the current literature, focusing on the types of cancers for which dysregulation of miR-665 has been associated with disease progression, recurrence, and/or prognosis. It needs to be emphasized that the role of miR-665 sometimes seems ambiguous, in the sense that it can be upregulated in one cancer type and downregulated in another and can even change during the progression of the same cancer. Caution is thus needed before using miR-665 as a biomarker, and extrapolation between different cancer types is not advisable. Moreover, more detailed understanding of the different roles of miR-665 will help in determining its potential as a diagnostic and prognostic biomarker.