Capabilities of miR-24 in exosomes in breast cancer cells

Abstract

Circulating tumor cells are cells that break away from a primary malignant site and circulate in the blood stream. From there, they can relocate to another part of the body, and cause metastasis. They can be used as biomarkers for cancer prognosis, and may also be used for cancer diagnosis in the presence of comorbid conditions. Micro RNAs (miRNA) are non-coding small RNAs found in humans that can degrade or upregulate protein transcription. miRNA is dependent on the Argonaute2 protein for incorporation into an RNA-induced silencing complex. miRNA utilizes exosomes to move outside the cytosol while being protected from extracellular enzymes such as RNases. miR-24 is implicated in many cancers, including breast cancer, and has the ability to upregulate the expression of its neighboring genes. As it has been shown that it can use the 3’untranslated regions on mRNA to influence expression of nearby targets, it also may influence its own transcription. The aim of this study was to evaluate the capability of transfected miR-24 to translocate into the nucleus of MCF-7 cells. It also evaluated the ability of transfected mirR-24 to integrate into exosomes, and whether this exosomal miRNA could similarly integrate into the nucleus in newly cultured cells. Results showed that transfected miR-24 does translocate into the nucleus of MCF-7 cells. It also showed that transfected miR-24 readily incorporates into exosomes. Because of procedural difficulties and time constraints, transfections with exosomal miR-24 have not yet been completed, but are a key next step in illustrating the ability of miR-24 to influence genetic expression on a broad spectrum. As miR-24 is upregulated in many disease states, including in many forms of breast cancer, the use of exosomes may outline a novel method for miRNA to integrate into malignant cells, and modulate protein transcription