Recently, modulation of some eukaryotic promoters by the estrogen receptor (ER) has been clarified at the molecular level; less is known about the control of expres- sion of the ER gene. In order to understand the mechanisms involved in its transcrip- tional regulation, we subcloned and sequenced a 2.8-kb genomic region upstream of the previously described initiation transcription site of the human ER gene.' A computer-assisted suggests that this region contains some new upstream ORFs and, according to other findings? a putative intronic sequence of 2 kb. RT-PCR experiments performed with specific oligonucleotide primers (FIG.1) demonstrate that (1)the ATG located at -2317 belongs to an upstream ER transcript and (2) this is transcribed in different breast cancer cell lines and tissues, but not in endometrial carcinomas (FIG.2A and B). Accordingly, an mRNA form hybridizing with the probe which includes the ORFs was detected by Northern blot (FIG.2C). The events leading to the production of this additional ER RNA are presently still unknown. However, these data demonstrate that the sequence upstream of -2317 might be a good candidate for an additional ER promoter region that might function differently depending on either tissue type or differentiation status. Moreover, at -1025 of the sequenced region there is an AlT-rich region including a (TA)26 dinucleotide repeat that is polymorphic in the p~pulation.W~e have investigated whether this polymorphism was related to ER gene expression. No differences in the allele number are found between normal and cancer breast samples of the same subject, nor does a relationship exist between the size of polymorphic alleles and the extent of ER content in the breast, endometrial, and kidney cancer cell lines analyzed. However, in these last DNA samples a low heterozygosity is present, suggesting loss of somatic alleles. Therefore, this polymorphism may be a useful marker to study the loss of constitutional heterozygosity on chromosome 6q.
Analysis of upstream sequences of the human estrogen receptor gene.
PIVA, Maria Roberta;DEL SENNO, Laura
1993
Abstract
Recently, modulation of some eukaryotic promoters by the estrogen receptor (ER) has been clarified at the molecular level; less is known about the control of expres- sion of the ER gene. In order to understand the mechanisms involved in its transcrip- tional regulation, we subcloned and sequenced a 2.8-kb genomic region upstream of the previously described initiation transcription site of the human ER gene.' A computer-assisted suggests that this region contains some new upstream ORFs and, according to other findings? a putative intronic sequence of 2 kb. RT-PCR experiments performed with specific oligonucleotide primers (FIG.1) demonstrate that (1)the ATG located at -2317 belongs to an upstream ER transcript and (2) this is transcribed in different breast cancer cell lines and tissues, but not in endometrial carcinomas (FIG.2A and B). Accordingly, an mRNA form hybridizing with the probe which includes the ORFs was detected by Northern blot (FIG.2C). The events leading to the production of this additional ER RNA are presently still unknown. However, these data demonstrate that the sequence upstream of -2317 might be a good candidate for an additional ER promoter region that might function differently depending on either tissue type or differentiation status. Moreover, at -1025 of the sequenced region there is an AlT-rich region including a (TA)26 dinucleotide repeat that is polymorphic in the p~pulation.W~e have investigated whether this polymorphism was related to ER gene expression. No differences in the allele number are found between normal and cancer breast samples of the same subject, nor does a relationship exist between the size of polymorphic alleles and the extent of ER content in the breast, endometrial, and kidney cancer cell lines analyzed. However, in these last DNA samples a low heterozygosity is present, suggesting loss of somatic alleles. Therefore, this polymorphism may be a useful marker to study the loss of constitutional heterozygosity on chromosome 6q.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
