RESUMO
BACKGROUND: The purpose of this study was to determine the contribution of different transactivating regions of the androgen receptor (AR) to the induction of androgen-regulated promoters in poorly (PC3 cells) and well-differentiated (LNCaP cells) prostate cancer cell lines. METHODS: PC3 and LNCaP cells were co-transfected with plasmids expressing full-length AR or deletion mutants together with luciferase reporters linked to the probasin (PB) and PSA promoters; as well as to ARR3tk, a PB-derived recombinant promoter. RESULTS: Androgen induction of the ARR3tk promoter in the presence of AR was 8- to 10-fold higher than that seen with the PB promoter. Activation of ARR3tk was greatest with an androgen-independent construct in which the first 231 amino acids and the ligand binding domain had been removed, indicating that this promoter is more responsive to activating functions in the N-terminal domain than in the ligand binding domain. By comparison, induction of the PB promoter was greatest with the full-length AR, which suggests that the ligand binding domain also makes a major contribution to the activation of this promoter. In similar analyses with the PSA promoter, AR regions required for promoter induction was dependent on the host cell type. In PC3 cells, the predominant AR transactivation function was androgen-independent and resided in the N-terminal domain, whereas in LNCaP cells, the highest level of induction was androgen dependent and also required participation of the ligand binding domain. CONCLUSIONS: Our results indicate that the relative utilization of transactivating functions in N-terminal and ligand binding domains of the AR is promoter and cell specific.
Assuntos
Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Receptores Androgênicos/genética , Proteína de Ligação a Androgênios/genética , Sequência de Bases , Sítios de Ligação/genética , Diferenciação Celular , Primers do DNA/genética , Genes Reporter , Humanos , Luciferases/genética , Masculino , Regiões Promotoras Genéticas , Antígeno Prostático Específico/genética , Neoplasias da Próstata/patologia , Receptores Androgênicos/química , Receptores Androgênicos/metabolismo , Deleção de Sequência , Timidina Quinase/genética , Ativação Transcricional , Transfecção , Células Tumorais CultivadasRESUMO
BACKGROUND: Although smaller variant forms of estrogen receptor (ER) messenger RNA (mRNA) have been detected in breast tumors, neither their prevalence nor their prognostic significance have been evaluated. Similarly, TRPM-2 mRNA, the product of a gene induced principally during the onset of apoptosis, is present in mouse and human breast cancer cell lines, but whether it also occurs in primary breast tumors and is related to disease outcome is unknown. METHODS: The relative expression and transcript size of ER mRNA and TRPM-2 mRNA in 126 primary breast tumors were measured by Northern analysis and compared with tumor grade, hormone receptor status, extent of tumor necrosis, and survival. RESULTS: In ER-positive tumors, 64% of the tumors had only the normal 6.5 kb ER mRNA, an additional 9% had the normal plus smaller ER mRNA, and 2% had variant forms. Only 8% of ER-negative tumors had ER mRNA transcripts. There were significant relationships between the occurrence of ER mRNA and low tumor grade, ER-positive receptor status, and better survival. In contrast, TRPM-2 mRNA was found in only 17% of breast tumors, none of which could be grouped with respect to grade, hormone receptor status, or survival. CONCLUSIONS: The presence of smaller variant forms of ER mRNA either alone or in association with the normal ER transcript is not indicative of an unfavorable prognosis, whereas TRPM-2 mRNA occurs in many primary breast tumors, but has no apparent relationship to survival.
Assuntos
Apoptose , Neoplasias da Mama/metabolismo , Glicoproteínas/genética , Chaperonas Moleculares , Proteínas de Neoplasias/genética , RNA Mensageiro/análise , Receptores de Estrogênio/genética , Adulto , Idoso , Neoplasias da Mama/mortalidade , Clusterina , Feminino , Humanos , Pessoa de Meia-Idade , Receptores de Estrogênio/análise , Taxa de SobrevidaRESUMO
In this paper we describe the coexistence of two forms of the transposable element Tc1 in the genome of the nematode Caenorhabditis elegans. A copy of the variant form has been isolated from the Bergerac genome and characterized. Restriction mapping and DNA sequencing have shown that a G to T transversion generated a HindIII restriction site to form the variant Tc1(Hin). The presence of this new restriction site makes this variant easily detectable on genomic blot hybridizations. There are approximately 20 copies of Tc1(Hin) amongst the Tc1's present in the Bergerac genome. Bergerac has approximately 250 copies of Tc1 per genome, whereas Bristol has about 30. In the Bristol strain we detected at least one copy Tc1(Hin). The ratio of Tc1(Hin) to total Tc1's is similar in the genomes of Bristol and Bergerac, even though they have markedly different total numbers of Tc1. Our results suggest that a trans-acting change in either the elements or the host genome was responsible for the expansion of Tc1 copy number in the Bergerac genome.