Role of chemokines and their receptors in cancer
ABSTRACT Metastases are the cause of 90% of human cancer deaths. The current treatment of cancer with chemo,- and/or radiotherapy is based on cell death by DNA damage neglecting the fact that cancer cell invasion into surrounding tissues and metastasizing are fundamental features of neoplasms and the major reason for treatment failure. Metastasis is the result of several sequential steps and represents a highly organized, non-random, and organ-selective process. A number of in vitro and in vivo models show that tumor cells use chemokine-mediated mechanisms during this metastasizing process, comparable to those observed in the regulation of leukocyte trafficking. Furthermore, chemokines modulate tumor behavior such as the regulation of tumor-associated angiogenesis, activation of host tumor-specific immunological responses, and direct stimulation of tumor cell proliferation in an autocrine fashion. These findings may lead to new drugs that target chemokines or their receptors and will likely be of great additional value for treatment of cancer patients.
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ABSTRACT: Environmental exposure to arsenic is known to cause various cancers. There are some potential relationships between cell malignant transformation and C-X-C chemokine receptor type 4 (CXCR4) expressions. Metastasis, one of the major characteristics of malignantly transformed cells, contributes to the high mortality of cells. CXCR4 and its natural chemokine ligand C-X-C motif ligand 12 (CXCL12) play a critical role in metastasis. Therefore, identification of nutritional factors which are able to inhibit CXCR4 is important for protection from environmental arsenic-induced carcinogenesis and for abolishing metastasis of malignantly transformed cells. The present study demonstrates that apigenin (4', 5, 7-trihydroxyflavone), a natural dietary flavonoid, suppressed CXCR4 expression in arsenic-transformed Beas-2B cells (B-AsT) and several other type of transformed/cancer cells in a dose- and time-dependent manner. Neither proteasome nor lysosome inhibitor had any effect in reducing the apigenin-induced down-regulation of CXCR4, indicating that apigenin-induced down-regulation of CXCR4 is not due to proteolytic degradation. The down-regulation of CXCR4 is mainly due to the inhibition of nuclear factor κB (NF-κB) transcriptional activity. Apigenin also abolished migration and invasion of transformed cells induced by CXCL12. In a xenograft mouse model, apigenin down-regulated CXCR4 expression and suppressed tumor growth. Taken together, our results show that apigenin is a novel inhibitor of CXCR4 expression. This dietary flavonoid has the potential to suppress migration and invasion of transformed cells and prevent environmental arsenic-induced carcinogenesis.Toxicology and Applied Pharmacology 06/2013; · 3.98 Impact Factor
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ABSTRACT: The human chemokine system includes approximately 48 chemokines and 19 chemokine receptors. The CXCL12/CXCR4 system is one of the most frequently studied that is also found overexpressed in a large variety of tumors. The CXCL12/CXCR4 axis has been increasingly identified as an important target in cancer growth, metastasis, relapse, and resistance to therapy. In this review, we highlight current knowledge of the molecular mechanisms involving chemokines CXCL12/CXCR4 and their consequences in head and neck squamous cell carcinoma (HNSCC). Overexpression of CXCL12/CXCR4 in HNSCC appears to activate cellular functions, including motility, invasion, and metastatic processes. Current findings suggest that CXCR4 and epithelial-mesenchymal transition markers are associated with tumor aggressiveness and a poor prognosis, and may be suitable biomarkers for head and neck tumors with high metastatic potential. Furthermore, knowledge of the role of CXCR4 in HNSCC could influence the development of new targeted therapies for treatment, aimed at improving the prognosis of this disease. © 2013 Wiley Periodicals, Inc. Head Neck, 2013.Head & Neck 03/2013; · 2.83 Impact Factor
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ABSTRACT: Increasing evidence indicates that the interaction between the CXC chemokine receptor-4 (CXCR4) and its ligand CXCL12 is critical in the process of metastasis that accounts for more than 90% of cancer-related deaths. Thus, novel agents that can downregulate the CXCR4/CXCL12 axis have therapeutic potential in inhibiting cancer metastasis. In this report, we investigated the potential of an agent, plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone), for its ability to modulate CXCR4 expression and function in various tumor cells using Western blot analysis, DNA binding assay, transient transfection, real time PCR analysis, chromatin immunoprecipitation, and cellular migration and invasion assays. We found that plumbagin downregulated the expression of CXCR4 in breast cancer cells irrespective of their HER2 status. The decrease in CXCR4 expression induced by plumbagin was not cell type-specific as the inhibition also occurred in gastric, lung, renal, oral, and hepatocellular tumor cell lines. Neither proteasome inhibition nor lysosomal stabilization had any effect on plumbagin-induced decrease in CXCR4 expression. Detailed study of the underlying molecular mechanism(s) revealed that the regulation of the downregulation of CXCR4 was at the transcriptional level, as indicated by downregulation of mRNA expression, inhibition of NF-κB activation, and suppression of chromatin immunoprecipitation activity. In addition, using a virtual, predictive, functional proteomics-based tumor pathway platform, we tested the hypothesis that NF-κB inhibition by plumbagin causes the decrease in CXCR4 and other metastatic genes. Suppression of CXCR4 expression by plumbagin was found to correlate with the inhibition of CXCL12-induced migration and invasion of both breast and gastric cancer cells. Overall, our results indicate, for the first time, that plumbagin is a novel blocker of CXCR4 expression and thus has the potential to suppress metastasis of cancer.Molecular Cancer 09/2011; 10:107. · 5.13 Impact Factor