trypsinogen and Melanoma

Controversy exists over melanogenesis of adult human RPE cells in vitro. This study investigated melanin content and production and expression of tyrosinase (TYR), tyrosinase-related-protein-1 (TRP1), tyrosinase-related-protein-2 (TRP2), and P gene in cultured human RPE cells and uveal melanoma cells.. RPE cells were isolated and cultured from three adult donor eyes. A continuous human uveal melanoma cell line was established from primary choroidal melanoma. Melanin content and production were measured, and the expression of TYR, TRP1, TRP2, and P gene at the mRNA and protein levels were detected by RT-PCR and western blot, respectively.. Melanin content per cell of cultured RPE decreased rapidly and in proportion to cell division. No melanin production could be demonstrated in any passages. In cultured RPE cells, mRNA expression of TYR, TRP1, TRP2, and P-gene and protein expression of TYR, TRP1, and TRP2 could not be detected. In uveal melanoma cells, melanin content per cell remained stable, and melanin production could be detected in each passage. Expression of mRNA of TYR, TRP1, TRP2, and P-gene and protein of TYR, TRP1, and TRP2 could be detected in melanoma cells.. Human RPE cells under standard culture circumstances do not produce melanin and do not express the four key genes required in melanin biosynthesis pathway. In contrast, human uveal melanoma cells produce melanin and express all of these melanogenic genes in vitro.

Topics: Adult; Blotting, Western; Cells, Cultured; Gene Expression; Humans; Melanins; Melanoma; Membrane Proteins; Membrane Transport Proteins; Monophenol Monooxygenase; Pigment Epithelium of Eye; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Trypsin; Trypsinogen; Uveal Neoplasms

Although it is accepted that regulatory T cells (T regs) contribute to cancer progression, most studies in the field consider nonantigen-specific suppression. Here, we show the presence of tumor antigen-specific CD4(+) T regs in the blood of patients with metastatic melanoma. These CD4(+) T regs recognize a broad range of tumor antigens, including gp100 and TRP1 (melanoma tissue differentiation antigens), NY-ESO-1 (cancer/testis antigen) and survivin (inhibitor of apoptosis protein (IAP) family antigen). These tumor antigen-specific T regs proliferate in peripheral blood mononuclear cells (PBMC) cultures in response to specific 15-mer peptides, produce preferentially IL-10 and express high levels of FoxP3. They suppress autologous CD4(+)CD25(-) T cell responses in a cell contact-dependent manner and thus share properties of both naturally occurring regulatory T cells and type 1 regulatory T cells. Such tumor antigen-specific T regs were not detected in healthy individuals. These tumor antigen-specific T regs might thus represent another target for immunotherapy of metastatic melanoma.

Topics: Adult; Aged; Antigens, Neoplasm; CD4-Positive T-Lymphocytes; Female; Forkhead Transcription Factors; gp100 Melanoma Antigen; Humans; Inhibitor of Apoptosis Proteins; Interleukin-10; Interleukin-2 Receptor alpha Subunit; Leukocytes, Mononuclear; Male; Melanoma; Membrane Glycoproteins; Membrane Proteins; Microtubule-Associated Proteins; Middle Aged; Neoplasm Metastasis; Neoplasm Proteins; Survivin; T-Lymphocytes, Regulatory; Trypsin; Trypsinogen