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Tissue distribution and differential expression of melanocortin 1 receptor, a malignant melanoma marker.

Salazar-Onfray F, López M, Lundqvist A, Aguirre A, Escobar A, Serrano A, Korenblit C, Petersson M, Chhajlani V, Larsson O, Kiessling R - Br. J. Cancer (2002)

Bottom Line: Immunohistochemistry revealed a strong expression of melanocortin 1 receptor in all tested primary and metastatic melanomas, but also demonstrated low levels of expression in adrenal medulla, cerebellum, liver and keratinocytes.Flow cytometry studies showed that melanocortin 1 receptor was expressed in in vitro activated monocytes/macrophages and in the THP-1 monocytic leukaemia line at levels of about 1 in 3 to 1 in 5 of that found in melanomas.Peripheral blood-derived dendritic cells, also express melanocortin 1 receptor in vitro.

View Article: PubMed Central - PubMed

Affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile. fsalazar@machi.med.unchile.cl

ABSTRACT
The melanocortin 1 receptor is a G-protein-coupled receptor, described to be expressed on melanomas and melanocytes. Subsequent RT-PCR studies demonstrated the presence of melanocortin 1 receptor mRNA in other tissues such as pituitary gland and testis. Previously, we have demonstrated that three HLA-A2 binding nonamer peptides derived from melanocortin 1 receptor can elicit peptide-specific CTL which can recognize target cells transfected with the melanocortin 1 receptor gene and MHC class I matched melanoma lines. The potential of targeting melanocortin 1 receptor in therapy and diagnosis will depend on a preferential expression of this receptor in the majority of primary and metastatic melanomas vs normal tissues. We tested a panel of melanomas, carcinomas and other cell lines for the presence of melanocortin 1 receptor, using two monoclonal antibodies. The receptor was detected in 83% of the tested melanoma cell lines but not in other carcinoma lines. Immunohistochemistry revealed a strong expression of melanocortin 1 receptor in all tested primary and metastatic melanomas, but also demonstrated low levels of expression in adrenal medulla, cerebellum, liver and keratinocytes. Flow cytometry studies showed that melanocortin 1 receptor was expressed in in vitro activated monocytes/macrophages and in the THP-1 monocytic leukaemia line at levels of about 1 in 3 to 1 in 5 of that found in melanomas. Peripheral blood-derived dendritic cells, also express melanocortin 1 receptor in vitro. This extensive analysis of melanocortin 1 receptor tissue distribution may be of relevance not only for melanoma immunology, but also for research on the pathogenicity of inflammatory conditions in the skin and neurologic tissues. It remains to be seen if the over-expression of melanocortin 1 receptor in melanomas is sufficiently high to allow a 'therapeutic window' to be exploited in cancer immunotherapy.

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MC1R is overexpressed on melanomas compared to stimulated monocytes. (A) α-MSH binds specifically to melanoma cells and to stimulated monocytes. Cells were incubated with biotin-labelled α-MSH for 1 h, washed, stained with PE-conjugated streptavidin and then analysed by FACS as described in Materials and Methods. (B) Intracellular expression of MC1R in melanoma cell lines, the monocytic line THP-1 and stimulated monocytes. Five melanoma cell lines (DFB mel, FM55 mel and BL mel, OCM1 and OCM3), the macrophage derived line THP-1, 7 day cultured dendritic cells (DCi) (showed as mean of three lines in B and separately (DC1, DC2 and DC3 in the histogram) and nonstimulated monocytes or monocytes incubated with cytokines for 48 h were fixed, permeabilised and incubated with mAb MP1-1B7. PE-conjugated secondary mAb were used for detection by FACS as described in Materials and Methods. These experiments were performed three times each with similar results.
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fig5: MC1R is overexpressed on melanomas compared to stimulated monocytes. (A) α-MSH binds specifically to melanoma cells and to stimulated monocytes. Cells were incubated with biotin-labelled α-MSH for 1 h, washed, stained with PE-conjugated streptavidin and then analysed by FACS as described in Materials and Methods. (B) Intracellular expression of MC1R in melanoma cell lines, the monocytic line THP-1 and stimulated monocytes. Five melanoma cell lines (DFB mel, FM55 mel and BL mel, OCM1 and OCM3), the macrophage derived line THP-1, 7 day cultured dendritic cells (DCi) (showed as mean of three lines in B and separately (DC1, DC2 and DC3 in the histogram) and nonstimulated monocytes or monocytes incubated with cytokines for 48 h were fixed, permeabilised and incubated with mAb MP1-1B7. PE-conjugated secondary mAb were used for detection by FACS as described in Materials and Methods. These experiments were performed three times each with similar results.

Mentions: To further compare the levels of MC1R expression between melanomas and stimulated monocytes, we also performed flow cytometry analysis of melanomas and monocytes stained with fluorescein-conjugated α-MSH. This analysis showed that melanomas bind five to seven times more to α-MSH than monocytes cultured in medium alone (Figure 5AFigure 5


Tissue distribution and differential expression of melanocortin 1 receptor, a malignant melanoma marker.

Salazar-Onfray F, López M, Lundqvist A, Aguirre A, Escobar A, Serrano A, Korenblit C, Petersson M, Chhajlani V, Larsson O, Kiessling R - Br. J. Cancer (2002)

MC1R is overexpressed on melanomas compared to stimulated monocytes. (A) α-MSH binds specifically to melanoma cells and to stimulated monocytes. Cells were incubated with biotin-labelled α-MSH for 1 h, washed, stained with PE-conjugated streptavidin and then analysed by FACS as described in Materials and Methods. (B) Intracellular expression of MC1R in melanoma cell lines, the monocytic line THP-1 and stimulated monocytes. Five melanoma cell lines (DFB mel, FM55 mel and BL mel, OCM1 and OCM3), the macrophage derived line THP-1, 7 day cultured dendritic cells (DCi) (showed as mean of three lines in B and separately (DC1, DC2 and DC3 in the histogram) and nonstimulated monocytes or monocytes incubated with cytokines for 48 h were fixed, permeabilised and incubated with mAb MP1-1B7. PE-conjugated secondary mAb were used for detection by FACS as described in Materials and Methods. These experiments were performed three times each with similar results.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2376124&req=5

fig5: MC1R is overexpressed on melanomas compared to stimulated monocytes. (A) α-MSH binds specifically to melanoma cells and to stimulated monocytes. Cells were incubated with biotin-labelled α-MSH for 1 h, washed, stained with PE-conjugated streptavidin and then analysed by FACS as described in Materials and Methods. (B) Intracellular expression of MC1R in melanoma cell lines, the monocytic line THP-1 and stimulated monocytes. Five melanoma cell lines (DFB mel, FM55 mel and BL mel, OCM1 and OCM3), the macrophage derived line THP-1, 7 day cultured dendritic cells (DCi) (showed as mean of three lines in B and separately (DC1, DC2 and DC3 in the histogram) and nonstimulated monocytes or monocytes incubated with cytokines for 48 h were fixed, permeabilised and incubated with mAb MP1-1B7. PE-conjugated secondary mAb were used for detection by FACS as described in Materials and Methods. These experiments were performed three times each with similar results.
Mentions: To further compare the levels of MC1R expression between melanomas and stimulated monocytes, we also performed flow cytometry analysis of melanomas and monocytes stained with fluorescein-conjugated α-MSH. This analysis showed that melanomas bind five to seven times more to α-MSH than monocytes cultured in medium alone (Figure 5AFigure 5

Bottom Line: Immunohistochemistry revealed a strong expression of melanocortin 1 receptor in all tested primary and metastatic melanomas, but also demonstrated low levels of expression in adrenal medulla, cerebellum, liver and keratinocytes.Flow cytometry studies showed that melanocortin 1 receptor was expressed in in vitro activated monocytes/macrophages and in the THP-1 monocytic leukaemia line at levels of about 1 in 3 to 1 in 5 of that found in melanomas.Peripheral blood-derived dendritic cells, also express melanocortin 1 receptor in vitro.

View Article: PubMed Central - PubMed

Affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile. fsalazar@machi.med.unchile.cl

ABSTRACT
The melanocortin 1 receptor is a G-protein-coupled receptor, described to be expressed on melanomas and melanocytes. Subsequent RT-PCR studies demonstrated the presence of melanocortin 1 receptor mRNA in other tissues such as pituitary gland and testis. Previously, we have demonstrated that three HLA-A2 binding nonamer peptides derived from melanocortin 1 receptor can elicit peptide-specific CTL which can recognize target cells transfected with the melanocortin 1 receptor gene and MHC class I matched melanoma lines. The potential of targeting melanocortin 1 receptor in therapy and diagnosis will depend on a preferential expression of this receptor in the majority of primary and metastatic melanomas vs normal tissues. We tested a panel of melanomas, carcinomas and other cell lines for the presence of melanocortin 1 receptor, using two monoclonal antibodies. The receptor was detected in 83% of the tested melanoma cell lines but not in other carcinoma lines. Immunohistochemistry revealed a strong expression of melanocortin 1 receptor in all tested primary and metastatic melanomas, but also demonstrated low levels of expression in adrenal medulla, cerebellum, liver and keratinocytes. Flow cytometry studies showed that melanocortin 1 receptor was expressed in in vitro activated monocytes/macrophages and in the THP-1 monocytic leukaemia line at levels of about 1 in 3 to 1 in 5 of that found in melanomas. Peripheral blood-derived dendritic cells, also express melanocortin 1 receptor in vitro. This extensive analysis of melanocortin 1 receptor tissue distribution may be of relevance not only for melanoma immunology, but also for research on the pathogenicity of inflammatory conditions in the skin and neurologic tissues. It remains to be seen if the over-expression of melanocortin 1 receptor in melanomas is sufficiently high to allow a 'therapeutic window' to be exploited in cancer immunotherapy.

Show MeSH
Related in: MedlinePlus