CCL27–CCR10 and CXCL12–CXCR4 chemokine ligand-receptor mRNA expression ratio: new predictive factors of tumor progression in cutaneous malignant melanoma

Abstract

CXCR4, CCR7 and CCR10 chemokine receptors are known to be involved in melanoma metastasis. Our goal was to compare the relative intratumoral mRNA expression of these receptors with that of their corresponding chemokine ligands, CXCL12, CCL19, CCL21, and CCL27 across the full spectrum of human melanoma progression: thin and thick primary melanomas, as well as "in transit", lymph node, and distant metastases. Expression was quantified by real-time RT-PCR in 103 melanoma samples: 51 primary tumors and 52 metastases. Particular emphasis was focused on chemokine ligand-receptor expression ratios. Immunohistochemistry was performed to identify the cell types expressing these molecules. CXCL12-CXCR4 and CCL27-CCR10 ratios were higher in thin than in thick primary melanomas, and all four chemokine-receptor ratios were higher in primary tumors than in melanoma metastases. CCL27-CCR10 and CXCL12-CXCR4 expression ratios in primary tumors were inversely associated with the development of distant metastases, and improved the predictive value of tumor thickness for distant metastasis, which is important since chemokine ligand-receptor ratios are not affected by the endogenous gene employed for normalizing mRNA expression. Both receptor and ligand immunolabeling were detected in neoplastic cells suggesting autocrine mechanisms. Our results support the concept that low CCL27/CCR10 and CXCL12/CXCR4 intratumoral mRNA ratios are associated with melanoma progression, and in combination with Breslow thickness, are the best predictive factors for the development of distant metastases in primary cutaneous melanoma.

Expression of the Chemokine Receptors CXCR3, CXCR4, CXCR7 and Their Ligands in Rhabdomyosarcoma

“…CXCR4 and CXCR7 have been reported to be higher in ARMS than in ERMS [21,27]; in agreement with this, in the present study we found significant lower CXCL12/CXCR7, CXCL11/ CXCR7 and CXCL12/CXCR4 ratios in ARMS than in ERMS xenografts. These results are equivalent to those reported in melanoma by Monteagudo et al [31] that found the lower ratio values in the most metastatic melanomas. In the same way, we found a significantly higher CXCL12/ CXCR4 ratio in primary ERMS than in their recurrences.…”

“…The chemokine ligand/receptor ratio has evidenced to be an excellent method for assessing chemokines available in a given tissue. In addition, this method is independent of the housekeeping gene selected for normalization, what contributes to a better standardization of the results [31,41]. CXCR4 and CXCR7 have been reported to be higher in ARMS than in ERMS [21,27]; in agreement with this, in the present study we found significant lower CXCL12/CXCR7, CXCL11/ CXCR7 and CXCL12/CXCR4 ratios in ARMS than in ERMS xenografts.…”

“…The attached antibodies were visualized by the avidin-biotin-peroxidase procedure (Dako, Carpentaria, CA, USA). The cell lines mel-RC-08 and Mel-Ho were used as positive controls [31,32]. Negative controls were used in each immunoreaction.…”

“…The final amount of the target gene, normalized to an endogenous reference gene (ΔCt = Ct target gene -Ct reference gene), was given by the formula: 2-ΔCt [33], which allowed for the comparison of the different samples of our study. The formula 2 -[ΔCt chemokine target gene -ΔCt chemokine receptor target gene] based in a previous work in melanoma [31], was used for the calculation of chemokine/chemokine-receptor mRNA ratios.…”

Intracellular coexpression of CXC- and CC– chemokine receptors and their ligands in human melanoma cell lines and dynamic variations after xenotransplantation

“…Recently, immunohistochemical expression of CXCR4, CCR7 and CCR10 and their ligands has been described in tumor cells from primary and metastatic melanomas. The CXCL12-CXCR4 and CCL27-CCR10 ratios quantified by real time RT-PCR were found to be significantly higher in thin than in thick primary melanomas, and inversely associated with the development of distant metastasis [23]. Although these studies demonstrate the production of chemokines by the tumor cells they do not necessarily indicate their secretion from the cell.…”