Ca(2+)-binding proteins S100A6 and S100B in primary cutaneous melanoma

Area of Science:

• Oncology
• Immunohistochemistry
• Molecular Biology

Background:

• Commercially available polyclonal antibodies against bovine S100 proteins are standard for melanoma immunohistochemistry.
• The exact human S100 protein composition of these antibodies is undefined, with 13 known human S100 proteins.
• There is a need for well-characterized antibodies for precise melanoma characterization.

Purpose of the Study:

• To evaluate the expression of four novel polyclonal antibodies against human recombinant S100 proteins (S100A1, S100A2, S100A4, S100A6) in cutaneous melanoma.
• To correlate the expression of these S100 proteins with standard S100 staining.
• To assess the relationship between S100 protein expression and the metastatic potential of primary melanomas.

Main Methods:

• Analysis of 39 formalin-fixed paraffin-embedded primary cutaneous melanomas.
• Immunohistochemical staining using the APAAP method with antibodies against recombinant human S100A1, S100A2, S100A4, and S100A6.
• Qualitative assessment of staining extent and calculation of a staining index, correlated with patient outcomes and metastatic potential.

Main Results:

• All specimens showed positive staining with S100A6 antibodies and conventional bovine S100 antibodies.
• No significant correlation was found between S100A6 or standard S100 protein expression and patient outcomes (metastatic potential, overall survival).
• Low expression levels of S100A1, S100A2, and S100A4 in melanomas precluded their statistical analysis.

Conclusions:

• S100A6 antibody staining was positive in all cases, though of lower quality compared to standard commercial S100 antibodies.
• The study highlights the availability of specific, well-characterized antibodies for individual S100 proteins.
• These new reagents offer potential for future, more precise immunohistochemical characterization studies in melanoma.