CBD Reverts the Mesenchymal Invasive Phenotype of Breast Cancer Cells Induced by the Inflammatory
Lázaro García-Morales, Aída M Castillo, José Tapia Ramírez, Horacio Zamudio-Meza, Ma del Carmen Domínguez-Robles and Isaura Meza
International Journal of Molecular Science, 2020, 21, 2429
doi : 10.3390/ijms21072429
Cannabidiol (CBD) has been used to treat a variety of cancers and inflammatory conditions with controversial results. In previous work, we have shown that breast cancer MCF-7 cells, selected by their response to inflammatory IL-1 cytokine, acquire a malignant phenotype (6D cells) through an epithelial mesenchymal transition (EMT).We evaluated CBD as a potential inhibitor of this transition and inducer of reversion to a non-invasive phenotype. It decreased 6D cell viability, downregulating expression of receptor CB1. The CBD blocked migration and progression of the IL-1-induced signaling pathway IL-1/IL-1RI/-catenin, the driver of EMT. Cannabidiol reestablished the epithelial organization lost by dispersion of the cells and re-localized E-cadherin and -catenin at the adherens junctions. It also prevented -catenin nuclear translocation and decreased over-expression of genes for DNp63, BIRC3, and ID1 proteins, induced by IL-1 for acquisition of malignant features. Cannabidiol inhibited the protein kinase B (AKT) activation, a crucial eector in the IL-1/IL-1RI/-catenin pathway, indicating that at this point there is crosstalk between IL-1 and CBD signaling which results in phenotype reversion. Our 6D cell system allowed step-by-step analysis of the phenotype transition and better understanding of mechanisms by which CBD blocks and reverts the eects of inflammatory IL-1 in the EMT.
Keywords : CBD; inflammatory IL1; signaling pathways; phenotype reversion; cancer treatment
Inflammation is considered a critical component of cancer progression. The presence of inflammatory cytokines in the tumor microenvironment has been linked to an aggressive phenotype in cancer cells . In particular, it has been proposed that increased levels of IL-1, derived from the microenvironment of malignant cells, activate inflammation that promotes invasiveness .
Previous work by our group has shown that binding of the inflammatory cytokine IL-1 to its receptor IL-1RI, present in non-invasive MCF-7 breast cancer cells, triggered the initiation of epithelial mesenchymal transition (EMT) by activation of the signaling pathway IL-1/IL-1R/-catenin [3–5]. The transition was initiated by striking modifications of the intercellular junctions and the actin cytoskeleton of the epithelial cells. The cells detached from each other acquiring a mesenchymal morphology and increased migration and invasiveness . Disorganization of cell–cell contacts led to internalization of cell junction proteins among those -catenins which were translocated to the nucleus. The -catenin acted as a transcriptional coactivator, modulating the expression of genes and proteins downstream of the IL-1-activated signaling pathway to complete the EMT and the acquisition of an aggressive phenotype of the so-called 6D cells. These data supported the proposal by us and other authors of a relationship between cancer development and an inflammatory microenvironment [6,7].
For several years cannabidiol, CBD, a constituent of Cannabis sativa without psychotropic eects, has been empirically used as an anti-inflammatory drug and modulator of cancer progression. Recent studies highlighted that CBD is toxic at dierent concentrations in diverse cells, making the results obtained in cell models and the clinic dicult to interpret and, therefore, for defining the proper dose for patients . On the other hand, in vitro studies have shown that activation of the cannabinoid receptors modulates dierent steps of tumorigenesis in several types of cancer [9,10]. It is known that CBD downregulates metastasis and replication in highly invasive cells by inhibiting expression of the ID-1 gene . Cannabidiol has also been proposed as an inducer of apoptosis and autophagy, two mechanisms involved in decrease of cancer cell growth . These reports have suggested that CBD has a potential role in the treatment of tumors and chronic inflammatory diseases. Therefore, a better understanding of the cellular and molecular mechanisms underlying CBD activities is imperative for its safe administration in patients, particularly when treatment is prolonged [8,13].
Our present work was directed to explore if the anti-inflammatory activity of CBD could hinder and reverse the IL-1-induced EMT, leading to malignancy. We used our breast cancer invasive 6D cells model [4,5]. It was found that 6D cells have high levels of CBD receptor CB1. CBD bound to CB1 is internalized and released in the cytoplasm. At this point, inactivation of AKT by CBD results in the inhibition of -catenin nuclear translocation and downregulation of genes and proteins identified as markers of malignancy in the activated EMT. The inactivation of AKT by CBD increased -catenin and E-cadherin expression, and their relocation at the cell contacts to form adherens junctions and recover an epithelial phenotype.