Tesi di Dottorato

Permanent URI for this communityTesi di Dottorato

Browse

Has files: YesSubject: search.filters.subject.Endocrinology

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Role of ERalpha/NOTCH4 axis in sustaining stemness in breast cancer cells
    (2018-02-27) Elena Spina, Elena Spina; Andò, Sebastiano
    Early detection and new therapeutic strategies have improved breast cancer patient outcome and survival rates in the last years. However, breast cancer still remains the second leading cause of cancer-related deaths among women worldwide, and approximately 30% of patients eventually experience a tumor relapse. Treatment failure is mainly due to metastatic process and resistance to conventional therapy. Over the past decade it has been established the existence of a subpopulation of cancer stem cell (CSC) within breast cancers that is responsible for tumor initiation, progression and resistance to endocrine therapies. It is well known the “driving role” of oestrogens and its receptor alpha (ERα), in development and progression of breast cancer disease, but still unknown their role in regulating breast CSCs (BCSCs). In the past few years, several studies revealed the presence of gain-of-function mutation in ESR1, gene encoding for ERα, in metastatic breast cancer patients after long-term endocrine therapies treatment. Particularly, Y537N, Y537S and D538G are the most frequent “hot spot” mutations within ERα hormone-binding domain (HBD) that lead to ligand-independent ERα activity and consequently, resistance to endocrine therapy. Here, we studied how HBD-ESR1 mutations might account for a mechanism of metastatic process and endocrine resistance, sustaining stem cell-like phenotype. As experimental model, we used breast cancer cell lines expressing wild-type and HBDESR1 mutations. Our results, using in vivo and in vitro experiment (mammosphereforming assay and CD44+/CD24- phenotype analysis) have suggested an enrichment of BCSCs activity by HBD-ESR1 mutations, that seems to be sustained by Notch4 signaling through constitutive hyper phosphorylation of Serine 118 residue of ERα that has been demonstrated related to stem cell phenotype and tumor initiation, in mutant-expressing cells. Experiments conducted using CRISPR-Cas9 knock-in of Y537S-ERα mutation confirmed the role of this mutation in tumor initiation and progression as obtained using HBD-ESR1 stable clones. We propose a potential novel role of HBD-ESR1 mutations in sustaining BCSCs activity, that could have clinical relevance, suggesting new molecular biomarker and target to aim better therapeutic strategies for ERα-positive breast cancer metastatic patients.
  • No Thumbnail Available
    Item
    Functional cooperation between GPER and AHR toward breast cancer progression
    (2019-04-11) Cirillo, Francesca; Cerra, Maria Carmela; Maggiolini, Marcello
    The cytochrome P450 1B1 (CYP1B1) is a heme-thiolate monooxygenase involved in both estrogen and environmental contaminants metabolism. For instance, CYP1B1 catalyzes the hydroxylation of 17-β estradiol (E2) leading to the production of 4-hydroxyestradiol that may act as a potent carcinogenic agent. In addition, CYP1B1 is overexpressed in different tumors including breast cancer. In this scenario, it is worth mentioning that CYP1B1 expression is triggered by estrogens through the estrogen receptor (ER)α in breast cancer cells. In the present study, we evaluated whether the G protein estrogen receptor namely GPER may provide an alternate route toward the expression and function of CYP1B1 in ER-negative breast cancer cells, in cancer-associated fibroblasts (CAFs) obtained from breast cancer patients, in CAFs derived from a cutaneous metastasis of an invasive mammary ductal carcinoma and in breast tumor xenografts. Our results show that GPER along with the EGFR/ERK/c-Fos transduction pathway can lead to CYP1B1 regulation through the involvement of a half-ERE sequence located within the CYP1B1 promoter region. As a biological counterpart, we found that both GPER and CYP1B1 mediate growth effects in vitro and in vivo. Altogether, these data suggest that estrogens in ER-negative cell contexts may engage the alternate GPER signaling toward CYP1B1 regulation. CYP1B1 is a well-known target gene of the aryl hydrocarbon receptor (AHR) that may be activated by the carcinogenic pollutant 3-methylcholanthrene (3MC). Hence, we aimed to provide novel insights into the molecular mechanisms by which 3MC and E2 may activate a cross talk between AHR and GPER transduction pathways leading to the stimulation of breast cancer cells and CAFs. In particular, our results demonstrate that 3MC and E2 trigger the EGFR/ERK/c-Fos signalling through both AHR and GPER toward the up-regulation of CYP1B1 and cyclin D1 as well as the stimulation of growth responses. Altogether, the present findings suggest that a functional interaction between AHR and GPER may occur toward breast cancer progression