hsa-miR-۳۲۶ has a different expression pattern in MCF-۷ cells and the MCF-۷-derived small extracellular vesicles

Small extracellular vesicles (sEVs) with size typically smaller than ۲۰۰ nm have the ability to transport a variety of substances including RNA, DNA and proteins to various cells. sEVs are also known to have a notable impact on the development of cancer. Among the different cargoes carried by sEVs, microRNAs (miRNAs) which are short single stranded RNA molecule with ۲۰-۲۳ nucleotides in length and transcribed from endogenous genes, are of significant importance. They serve a crucial role function in preserving cellular homeostasis and controlling various cellular processes such as proliferation, differentiation, apoptosis, autophagy, and metabolism. miR-۳۲۶ as a tumor suppressor microRNA has been well established. As the evidence shows, the reduced level of miR-۳۲۶ in tumor cells leads to the activation of proto oncogenes, whereas increased expression of miR-۳۲۶ suppresses them. This motivated us to evaluate the expression level of miR-۳۲۶ in the sEVs derived from a ER/PR positive breast cancer cell line using the stem-loop method, a microRNA specific technique to assess the expression of diverse microRNAs. Methods sEVs were first extracted from the MCF-۷ cells media using the EXOCIB kit (EXOCIB, Iran), based on the precipitation method. The sEVs were then characterized by DLS and TEM. Afterward, total RNA was extracted from both MCF-۷ cells and their sEVs, and then the quality and quantity of the RNA were evaluated using NanoDrop spectrophotometer and ۲.۵% agarose gel electrophoresis. cDNA was synthesized via miR-۳۲۶ stem loop and the expression level of miR-۳۲۶ in the samples was determined by qPCR technique. Results were normalized by the expression level of U۶ as internal control then the relative expression was calculated using delta Ct method. Results miR-۳۲۶ as a tumor suppressor microRNA was under-expressed in MCF-۷ cells, whereas the level of this micro RNA in the MCF-۷ cells derived sEVs exhibited a significant over expression in comparison to the origin cell. Conclusion sEVs containing microRNAs can modulate the expression of key genes, rendering them a subject of considerable significance. Consequently, exploring the microRNA content within sEVs holds promise for yielding valuable insights into the prognosis and diagnosis of breast cancer. Moreover, a comprehensive investigation of the microRNA profile present in small EVs derived from MCF-۷ cells is recommended. Employing a systems biology approach may facilitate the identification of potential targets of miR-۳۲۶. Furthermore, synthetic oligonucleotides can be employed to either suppress or enhance the functional effects of miR-۳۲۶ for experimental manipulation purposes.

کلیدواژه ها:

Breast cancer ، microRNAs ، small extracellular vesicles ، stem-loop method