Abstract 2299: IL-8 receptor CXCR1 expressed in human breast epithelial cells MCF-10F is down regulated by human chorionic gonadotropin and its peptide 81-95

Abstract

Abstract Our findings that 17β-estradiol (E2) initiates neoplastic transformation of human breast epithelial cells (HBECs) led us to clarify the relationship between normal breast epithelial cells and cancer stem cells (CSCs). HBECs MCF-10F transformed in vitro by E2 express increased colony efficiency, invasiveness and tumorigenesis in SCID mice and lose ductulogenesis in collagen (The FASEB J 20:1622, 2006). Cancer progression is associated with gene dysregulation and chromosomal aberrations, amplifications and losses. Progressive changes occur from transformed to tumorigenic and tumor-derived cell lines in the integrin signaling pathway, inhibition of apoptosis, acquisition of tumorigenic cell surface and mesenchymal markers, like fibronectin, vimentin, and N-cadherin (CDH2) during epithelial-mesenchymal transition (EMT) (Cancer Res 67:11147, 2007), while epithelial markers E-cadherin (CDH1), occludin (OCLN), desmoplakin, and cytokeratins progressively decrease. The cell surface molecule CD44+/CD24/low phenotype, a marker for tumor-initiating cells, is significantly increased in tumorigenic and tumor derived cell lines. Loss of ductulogenesis in E2 transformed cells in collagen is reverted by human chorionic gonadotropin (hCG), a hormone that induces differentiation of the breast epithelium. Since hCG binds to the G-protein coupled receptor (GPCR) luteinizing hormone/chorionic gonadotropin receptor (LH/CG-R), and the cytokine IL-8 receptor (CXCR1), which has been shown to be expressed by cells displaying stem cell characteristics, we determined by RT-PCR the content of CXCR1 in MCF-10F cells and tested the effects of recombinant hCG (r-hCG) and of a 15 aminoacid peptide containing the sequence 8l-95 of the hCG beta chain on the expression levels of LH/CG-R and CXCR1 mRNA in MCF-10F cells. MCF-10F cells were daily treated with: 1) 50 IU/ml r-hCG (Ovidrel®, mD-Serono); 2) 20 µM 81-95 peptide (pp81-95), sequence SYAVALSCQCALCRR-NH2 synthesized by aapptec (Louisville, KY), or 3) vehicle only. Cells were harvested for RNA extraction and cell count at 0, 1, 2, 4, 6, 8, 10 and 15 days of treatment. r-HCG and pp81-95 decreased cell growth by 48%. Both compounds up-regulated LH/CG-R expression from 2.2 to 11.7 fold and down-regulated CXCR1 expression by 1.5 to 4.1 fold. Our novel findings that MCF-10F cells express CXCR1 further confirm a CSC characteristic of these cells. Furthermore, the fact that both r-hCG and its peptide downregulate the expression of CXCR1 while upregulating the expression of the LH/CG-R confirm the differentiating effects of hCG and pp81-95, respectively and support the use of this compounds in cancer preventive and therapeutic strategies. Work supported by Grant KG101080 from Susan G Komen for the Cure. (S.M.R. Noronha and S.A.A.C.Noronha internships at BCRL were supported by CAPES process # 4036-09-3 and 2359-09-0 and by FAPESP). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2299. doi:10.1158/1538-7445.AM2011-2299