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Current advances in molecular profiling methodologies and the accessibility of multi-omics datasets are paving the way toward a better understanding of heterogeneous diseases, including breast cancer (BC). In this regard, we sought to uncover the transcriptional changes triggered by estrogen and insulin in a primary BC cell line (BCAHC-1), which expresses the 46kDa isoform of the estrogen receptor (ER)α and the insulin receptor, as we have previously ascertained. Raw data from RNA sequencing of BCAHC-1 cells were processed by the Bcl2Fastq 2.20 version of the Illumina pipeline, while in silico analyses were performed in R Studio using the TCGA dataset. Real-time PCR, immunoblotting, ELISA and chromatin immunoprecipitation experiments were used to identify the molecular events triggered by estrogen and insulin in BCAHC-1 cells and cancer-associated fibroblasts (CAFs). Furthermore, migration and invasion assays allowed us to ascertain the mechanisms triggering these biological responses in the presence of the aforementioned hormone treatments. First, we determined that 17β-estradiol (E2) and insulin stimulate a peculiar IL-11 expression and IL-11 secretion in BCAHC-1 cells. Thereafter, bioinformatics analyses confirmed the up-regulation of IL-11 in ER-positive BCs, with respect to adjacent normal tissues, and its association with worse survival. Next, the involvement of IL-11 in pro-metastatic transduction signaling was established via pathway enrichment analyses. Notably, we found that the secretion of IL-11 by BCAHC-1 cells prompts an invasive phenotype of CAFs through the up-regulation of genes belonging to the extracellular matrix organization pathway, namely, the intercellular adhesion molecule 1 and integrin alpha 5. Overall, our findings indicate that IL-11 secretion by BC cells may elicit a paracrine action on the surrounding stroma and introduce invasive properties, suggesting that IL-11 could be considered a valuable target in comprehensive treatments of ER-positive BC patients. [ABSTRACT FROM AUTHOR]

Metabolic disorders, such as obesity, type 2 diabetes (T2D) and metabolic syndrome, have been implicated in breast cancer (BC) progression. In this regard, insulin has been shown to promote mitogenic and metastatic responses in BC through diverse signaling pathways. Moreover, high levels of insulin and elevated expression of its cognate receptor, namely insulin receptor (IR), have been associated with increased BC incidence, resistance to treatments and poor outcomes. Metformin (1,1-dimethylbiguanide hydrochloride) is the most commonly prescribed drug for T2D treatment worldwide. Metformin has been shown to interfere with BC cell growth. In order to provide novel insights through which metformin can elicit anti-cancer responses in BC, we performed bioinformatics analysis as well as TaqMan Gene Expression Assay, flow cytometry, immunofluorescence, immunoblots, 2D and 3D proliferation assays and motility experiments. A naturally immortalized BC cell line (namely BCAHC-1) and important components of the tumor microenvironment, such as cancer-associated fibroblasts (CAFs) derived from BC patients, were used as model systems. We found that metformin inhibits the activation of main transduction pathways, the gene expression changes and the proliferative effects induced by insulin in BCAHC-1 cells. Moreover, metformin prevented the insulin-stimulated induction of CXC chemokine receptor 4 (CXCR4), which has been involved in BC metastatic dissemination. Next, metformin suppressed the invasion of CAFs triggered through CXCR4 via insulin stimulated BCAHC-1 cells. Our findings may suggest novel transduction mechanisms involved in the inhibitory effects elicited by metformin in both BC cells and CAFs. [ABSTRACT FROM AUTHOR]