ABSTRACT
Breast cancer (BC) is a major health problem for women around the world. Although advances in the field of molecular therapy have been achieved, the successful therapeutic management of BC, particularly metastatic disease, remains a challenge for patients and clinicians. One of the areas of current investigation is the circulating tumor cells (CTCs), which have a determinant role in the development of distant metastasis. At the present, many of the available treatment strategies for metastatic disease are of limited benefit. However, the elucidation of the mechanisms of tumor progression and metastasis may help to identify key molecules/components that may function as therapeutic targets in the future. In the present study, the functional analysis of CTCs revealed their ability to grow and proliferate to form colonies. Immunofluorescence staining of the CTCs' colonies exhibits elevated expression of cell growth and survival associated proteins such as, survivin, ERK and Akt1. More importantly, the functional screening of the chemokine profile in BC patients' sera revealed an HR-independent elevation of the chemokine CXCL10 when compared to healthy controls. The analysis of chemokines CXCL9 and CXCL11 demonstrated an HR-dependent production pattern. The levels of both CXCL9 and CXCL11 were markedly high in HR+ patients' sera when compared to HR- patients and healthy controls. The functional analysis of HR+ and HR- BC derived cell lines when cultivated in media supplemented with patients' sera demonstrated the alteration of tumor progression and metastasis related proteins. We noted the induction of survivin, ß-catenin, MKP-1, pERK, CXCR4 and MMP-1 both at the protein and mRNA levels. The induction of those proteins was in keeping with patients' sera induced cell proliferation as measured by the MTT assay. In conclusion, our data emphasizes the role of chemokines, especially CXCL10, in BC progression and metastasis via the induction of signaling pathways, which mainly involve survivin, ß-catenin, MKP-1 and MMP-1.
Subject(s)
Breast Neoplasms/genetics , Chemokine CXCL10/metabolism , Gene Expression Regulation, Neoplastic , Breast Neoplasms/pathology , Case-Control Studies , Cell Line, Tumor , Cell Proliferation , Chemokine CXCL10/genetics , Chemokine CXCL11/genetics , Chemokine CXCL11/metabolism , Chemokine CXCL12/genetics , Chemokine CXCL12/metabolism , Chemokine CXCL9/genetics , Chemokine CXCL9/metabolism , Disease Progression , Dual Specificity Phosphatase 1/genetics , Dual Specificity Phosphatase 1/metabolism , Female , Humans , Inhibitor of Apoptosis Proteins/genetics , Inhibitor of Apoptosis Proteins/metabolism , MCF-7 Cells , Matrix Metalloproteinase 1/genetics , Matrix Metalloproteinase 1/metabolism , Neoplasm Metastasis , Neoplastic Cells, Circulating/pathology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, CXCR3/genetics , Receptors, CXCR3/metabolism , Receptors, CXCR4/genetics , Receptors, CXCR4/metabolism , Signal Transduction , Survivin , beta Catenin/genetics , beta Catenin/metabolismABSTRACT
The risk posed by breast cancer represents a complex interaction among factors affecting tumor immunity of the host. Toll-like receptors (TLRs) are members of the innate immune system and generally function to attract host immune cells upon activation. However, the good intentions of TLRs are sometimes not transferred to positive long-term effects, due to their involvement in exacerbating inflammatory effects and even contributing to continued inflammation. Chronic inflammatory states are considered to favor an increased predisposition to cancer, with continuous activation of inflammatory cytokines and other hallmarks of inflammation exerting a deleterious effect. Circulating tumor cells (CTCs) are neoplastic cells present in the peripheral blood circulation that have been found to be an indicator of disease progression and long-term survival. In the present study, we examined the expression of TLRs on dendritic cells, which play a major role in eliciting anti-tumor immunity, in metastatic breast cancer patients with CTCs. Flow cytometric data showed significant differences between circulating tumor cell (CTC) positive patients and CTC negative patients in their expression of TLR2 by CD8 positive cytotoxic T cells and TLR2, TLR4, TLR3, and TLR8 by CD11c positive dendritic cells (p<0.05). Expression of TLR2, TLR4, and TLR8 was increased in CTC positive patients, whereas TLR3 expression was decreased in the dendritic cell population.
