In recent years, cancer has threatened human life and health, emerging as a predominant source of mortality globally [1]. One of the most frequently recognized cancers, breast cancer constitutes the second most prominent source of cancer-attributable mortalities across the globe for the female gender [2]. Due to its notable genomic heterogeneity, triple-negative breast cancer (TNBC) is a unique subtype that is especially nonresponsive to conventional therapy. Therefore, there is an urgent need for innovative therapeutic strategies aimed at enhancing the outcomes for patients diagnosed with TNBC [3].

Multiple signal transduction cascades, such as TGF-β, JAK/STAT, Wnt, β-catenin, Notch, Hedgehog, and PI3K/AKT are crucial in various aspects of oncogenesis. Notably, disruption of the PI3K/AKT axis is linked to enhanced cancer cell survival, proliferation, and movement to new areas [4]. In TNBC, the PI3K/AKT/mTOR signaling pathway is more expressed and active [5]. This is one of the most essential intracellular signaling pathways, responding to hormone and growth factors' activation and governing tumor formation, metabolism, proliferation, and angiogenesis [6]. As a result, inhibiting this route could greatly slow tumor development.

MicroRNAs(miRNAs), a group of therapeutic RNAs, regulate a wide range of their target mRNAs that participate in the growth and invasion of many types of cancers [7]. miRNAs have critical functions in the study of cancer biology and can function as tumor suppressor (tsmiR) or oncogenic miRNAs (oncomiR) [8]. Moreover, miRNAs can tune the transcriptional activity of multiple pivotal genes implicated in diverse signaling cascades related to the tumorigenesis of many cancers, such as breast cancer [9]. Interestingly, research has demonstrated that miR-3143 is significantly reduced in clinical samples as well as TNBC cell lines. According to bioinformatics research, miR-3143 may target the AKT1 and PIK3CA genes, which could result in TNBC patients having an overexpressed PI3K/AKT/mTOR signaling pathway [10].

The method of delivery for therapeutic miRNAs is crucial for their efficacy. Numerous studies are currently focused on developing safe carriers for delivering therapeutic miRNAs. Exosomes are membrane-enclosed nanoparticles released manifested in a multiplicity of cellular phenotypes, including stem cells. They have showcased their utility as effective pathways for promoting cellular communication [11]. Mesenchymal stem cell (MSC)-derived exosomes have garnered significant interest for their regenerative and immunomodulatory properties [12]. Research has indicated that exosomes from MSCs possess immunosuppressive and tumor-suppressive effects, making them valuable in therapeutic strategies within animal models [13]. Umbilical Cord Mesenchymal Stem Cells (HUCMSCs) represent an supreme source of exosomes for therapeutic applications, owing to their favorable characteristics, including efficient cytokine secretion, low immunogenicity, ease of isolation, and reduced risk of contamination. Consequently, HUCMSC-derived exosomes have been identified as possible therapeutic agents [14,15].

However, one restriction of the research about miR-3143 was the absence of experimental validation for this targeting, particularly through techniques such as luciferase assays. To address this, our study involved the independent cloning of the 3′ UTR of PIK3CA and AKT1 mRNAs into a luciferase-containing plasmid, followed by a reporter assay (dual-luciferase) to experimentally confirm the influence of miR-3143 on these target genes. Additionally, we explored the effects of delivering miR-3143 to TNBC cells via exosomes secreted from HUCMSC, assessing its impact on the proliferative, invasive, and apoptotic properties of TNBC cells.