Expression of genes for microphthalmia isoforms, Pax3 and MSG1, in human melanomas
Language English Country France Media print
Document type Comparative Study, Journal Article, Research Support, Non-U.S. Gov't
PubMed
10644012
Knihovny.cz E-resources
- MeSH
- DNA-Binding Proteins biosynthesis genetics MeSH
- Humans MeSH
- Melanins biosynthesis MeSH
- Melanocytes metabolism MeSH
- Melanoma genetics metabolism MeSH
- RNA, Messenger biosynthesis MeSH
- Tumor Cells, Cultured metabolism MeSH
- Neoplastic Stem Cells metabolism MeSH
- Neoplasm Proteins biosynthesis genetics MeSH
- Neoplasms metabolism pathology MeSH
- Reverse Transcriptase Polymerase Chain Reaction MeSH
- Protein Isoforms biosynthesis genetics MeSH
- Gene Expression Regulation, Neoplastic * MeSH
- RNA, Neoplasm biosynthesis MeSH
- Salivary Proteins and Peptides biosynthesis genetics MeSH
- PAX3 Transcription Factor MeSH
- Microphthalmia-Associated Transcription Factor MeSH
- Paired Box Transcription Factors MeSH
- Transcription Factors * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
- Names of Substances
- DNA-Binding Proteins MeSH
- Melanins MeSH
- RNA, Messenger MeSH
- MITF protein, human MeSH Browser
- Neoplasm Proteins MeSH
- PAX3 protein, human MeSH Browser
- Pax3 protein, mouse MeSH Browser
- Protein Isoforms MeSH
- RNA, Neoplasm MeSH
- Salivary Proteins and Peptides MeSH
- Smr3a protein, mouse MeSH Browser
- PAX3 Transcription Factor MeSH
- Microphthalmia-Associated Transcription Factor MeSH
- Paired Box Transcription Factors MeSH
- Transcription Factors * MeSH
Microphthalmia (MITF) gene product, a transcription factor of the basic-helix-loop-helix type, is thought to play a role in the regulation of genes encoding the enzymes necessary for melanogenesis. These include tyrosinase, TRP-1 and TRP-2. Melanocyte-specific isoform of microphthalmia, MITF-M, is expressed in normal and malignant melanocytes. The presence of two other isoforms of microphthalmia, MITF-A and MITF-H, which differ from MITF-M in the amino-terminus, was demonstrated also in some non-melanocytic lineages. Here we have analyzed the presence of all three known isoforms of MITF mRNA in a panel of 17 human melanoma cell lines by a reverse transcriptase-polymerase chain reaction using isoform-specific primers. While, as expected, the predominant form in melanoma cell lines was MITF-M, low amounts of MITF-A mRNA was found in almost all melanomas, as well as in most of 20 tumor cell lines of the non-melanocyte origin (lung and colon carcinomas, osteosarcomas and neuroblastomas). The expression of MITF-H was not detected, with a few exceptions, in the tested cell lines. Pax3 transcription factor was reported earlier to regulate positively the melanocyte-specific promoter of the MITF gene. We found here that the Pax 3 mRNA was expressed in all melanoma cell lines, even in those that had repressed the MITF-M and were amelanotic. This suggests that additional factors, besides Pax3, are required for the MITF expression. The MSG1 (melanocyte-specific gene 1), a gene originally isolated from melanocytes and containing a strong transcription activation domain, was also found expressed in all melanomas and most non-melanocyte tumor cell lines. Together, these data indicate that the MITF-M isoform is the major type of MITF mRNA present in human melanoma cell lines and show that the expression of the isoform MITF-A and the MSG1 is not restricted to malignant melanocytes and occurs in a wide range of tumor cell lines.
