The goal of this study was to determine which of the 10 functional
metallothionein (MT) genes are expressed in four human
breast cancer cell lines and whether expression varies among the cell lines. Using reverse transcription polymerase chain reaction (RT-PCR) technology, it was shown that there was no expression of
mRNA for the MT-1A, MT-1B, MT-1F, MT-1G, MT-1H, MT-3, and MT-4 genes in any of the four cell lines. All four cell lines were shown to express
mRNA for the MT-2A and
MT-1X genes. The expression level of
mRNA for the MT-2A gene demonstrated modest differences among the cell lines, whereas expression of the
MT-1X gene was consistent. In contrast,
mRNA for the MT-1E gene was expressed in only two of the four cell lines and expression correlated to the
estrogen receptor status of the cell lines. The two
estrogen-receptor-positive cell lines showed no
mRNA expression for the MT-1E gene. In the two
estrogen-receptor-negative cell lines,
mRNA expression for the MT-1E gene was elevated with expression levels similar to the housekeeping gene,
glyceraldehyde-3-phosphate dehydrogenase. The cellular content of MT
protein was also shown to be elevated in the
estrogen-receptor-negative cell lines that express MT-1E
mRNA. These results suggest a possible relationship between
estrogen receptor status and MT-1E gene expression in human
breast cancer.