[Characteristics of a positive regulatory element in the first intron of the mts1 gene]. / Kharkteristika pozitivnogo reguliatornogo élementa v pervom introne gena mts1.

The first intron of the mts1 gene, a gene which is selectively expressed in metastatic cells and in normal cells that are motile, was found to be highly homologous to the CD3 delta enhancer element. Because of the homology between the CD3 delta enhancer and the first intron of mts1, we analysed the first intron of the mts1 gene to determine whether it functions as a transcriptional regulatory element. Highly metastatic CSML-0 cells transfected with chloramphenicol acetyltransferase containing plasmids demonstrated the ability of the mts1 first intron to function as a positive regulatory element. In vitro footprinting analysis using extracts from CSML-0 cells (which express mts1 at low levels) of CSML-100 cells (which express mts1 at high levels) identified a protected 16 nucleotide element in the first intron of mts1, regardless of the extract used. However, in vivo footprinting analysis of the same region identified the protected 16 nucleotide fragment only in the mts1 intron from CSML-100 cells, not from CSML-0 cells. Differences in the methylation pattern of the mts1 gene in CSML-100 cells and CSML-0 cells are known to exist, and may in part be responsible for the mts1 footprinting differences observed in vivo from the different cells lines.

[Structural and functional analysis of the promoter region of the mts1 gene]. / Struktunyi i funktsional'nyi analiz promotornoi oblasti gena mts1.

The mts1 gene is specifically expressed in metastatic tumors but not in non-metastatic counterparts. The gene was cloned from both mouse and human sources. The 5'-flanking regions of the mts1 gene from both sources were sequenced, revealing a 135 base pair region of high homology in the vicinity of the TATA box. The 5' region of the mts1 gene was also observed to have high degree of homology with some known promoter and enhancer sequences. The results of our transient transfection assays, in conjunction with those obtained from in vivo and in vitro footprinting of the promoter region, show no evidence of cis-control elements important for transcriptional regulation of mts1 gene. mts1 was found to be hypermethylated in CSML-0 cells and in the tissue types that do not express the gene or do that only at low levels. The possible role of methylation in progression of the nonmetastatic CSML-0 adenosarcoma cell line towards the metastatic CSML-100 adenosarcoma cell line will be discussed.