TLR expression in human melanoma cells

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• Melanoma cells are known to express Toll-like receptors (TLRs) 2, 3, and 4.
• The expression patterns of other TLRs in melanoma remain largely uncharacterized.

Purpose of the Study:

• To investigate the expression of TLR2, -3, -4, -7, -8, and -9 in melanoma cell lines and melanoma-invaded lymph nodes.
• To determine both mRNA and protein expression levels of these TLRs.

Main Methods:

• Quantitative reverse transcription-polymerase chain reaction (RT-PCR) for mRNA analysis.
• Ex vivo immunohistochemistry and in vitro flow cytometry for protein expression analysis.

Main Results:

• Melanoma cells expressed TLR2, -3, -4, -7, and -9 mRNA in vitro and potentially ex vivo.
• TLR2 and -4 protein expression was high ex vivo (>50%) but absent in vitro.
• TLR-3 and -8 proteins showed low ex vivo expression with high in vitro expression.
• TLR-7 and -9 proteins were expressed both ex vivo and in vitro.
• This study is the first to demonstrate TLR7 and -8 expression in melanoma cells.

Conclusions:

• Melanoma cells express a range of TLRs, including TLR7 and -8, which was previously unknown.
• Differential expression of TLRs at mRNA and protein levels, and between in vitro and ex vivo settings, suggests complex regulatory mechanisms in melanoma.