A cDNA clone, pHT gamma 1, representing human tyrosinase mRNA was isolated by screening a melanoma cDNA library with a synthetic oligonucleotide complementary to a segment of the human tyrosinase cDNA, Pmel 34 [Kwon et al.(1987) Proc. nat.Acad.Sci.USA 84, 7473-7477].
Tyrosinase transcripts of the same size and abundance were detected in a subset (three of eight) of nonpigmented, tyrosinase-negative melanoma cell lines, suggesting that post-transcriptional events are important in regulating tyrosinase activity.
We examined the relationship between pigment content and tyrosinase mRNA levels among human melanoma and melanocyte lines with very different levels of basal pigmentation; between two clones of a single human melanoma line, one pigmented and one amelanotic; and sequentially in melanocytes before and after simulation with isobutylmethylxanthine to increase melanin content per cell.
Molecular control of melanogenesis in malignant melanoma: functional assessment of tyrosinase and lamp gene families by UV exposure and gene co-transfection, and cloning of a cDNA encoding calnexin, a possible melanogenesis "chaperone".
Expression of an extended panel of cytokine genes was investigated by reverse polymerase chain reaction (PCR) in 10 freshly excised melanoma metastases infiltrated by lymphocytes (TIL). cDNA encoding for CD3-delta and tyrosinase could be amplified in all samples, confirming the presence of T lymphocytes and melanoma cells.
By using species-specific PCR amplification to distinguish fibroblast and melanoma cDNAs, it was demonstrated that the previously silent fibroblast tyrosinase and b-locus genes were transactivated following chromosomal transfer into pigmented melanoma cells.
The purpose of this study was to evaluate whether tyrosinase mRNA is detectable in the peripheral blood of patients with uveal and cutaneous melanoma and in patients with uveal melanoma undergoing surgical procedures on the eye harbouring the tumour.
Cutaneous melanomas of Tyr-SV40E transgenic mice (mice whose transgene consists of the tyrosinase promoter fused to the coding regions of simian virus 40 early genes) strikingly resemble human melanomas in their development and progression.
The activity of tyrosinase extracted from pigmented human melanoma cells (MNT-1) that were grown in the presence of homocysteine was reduced in comparison to that extracted from cells grown without homocysteine.
Since melanocytic cells are characterized by their pigmentation, and since tyrosinase is the key enzyme involved in melanogenesis, we studied the expression of a reporter gene which is under the control of the tyrosinase promoter or a combination of melanocyte-specific enhancer and tyrosinase promoter in ten human melanoma and four epithelial cell lines.
For example, it has been shown that formation of (HO)2IndCOOH from dopachrome is catalyzed by dopachrome tautomerase, that the melanogenic protein tyrosinase-related protein (TRP)-1 can oxidize (HO)2IndCOOH to its indole quinone, that (HO)2IndCOOH-melanins can be synthesized chemically, that mammalian melanins are naturally rich in (HO)2IndCOOH subunits, and that (HO)2IndCOOH is incorporated into melanins of melanomas in mice.
A construct consisting of 209 bp of the human tyrosinase promoter linked to two enhancer elements was demonstrated to drive high-level, melanoma-specific expression of a beta-galactosidase (beta-gal) reporter gene in transient transfection assays.
The purpose of this study was to determine the sensitivity of a RT-PCR-based assay for tyrosinase mRNA from peripheral blood and evaluate correlations with tumor status in melanoma patients.
Different techniques of blood collection, RNA isolation, and RT-PCR were compared, and the detectability of tyrosinase mRNA was tested using nine different melanoma cell lines.
To evaluate the specificity and applicability to the study of human tumor cells of the reverse transcription (RT) in situ PCR and RT polymerase chain reaction (PCR) in situ hybridization techniques, we examined five melanoma cell lines and five nonmelanoma lines for tyrosinase mRNA using primers specific for tyrosinase.