RESUMO
The long arm of chromosome 8 is one of the most common regions of amplification in cancers of several organs, especially carcinomas of the breast and prostate. TRPS1, MYC and EIF3S3 genes are located in one of the minimal regions of amplification, 8q23-q24, and have been suggested to be the target genes of the amplification. Here, our goal was to study copy number and expression of the three genes in order to investigate the significance of the genes in breast and prostate cancer. By using fluorescence in situ hybridisation (FISH), we first found that TRPS1 and EIF3S3 were amplified together in about one-third of hormone-refractory prostate carcinomas. Next, we analysed the mRNA expression of the three genes by real-time quantitative RT-PCR and the gene copy number by FISH in six breast and five prostate cancer cell lines. Breast cancer cell line, SK-Br-3, which contained the highest copy number of all three genes, showed overexpression of only EIF3S3. Finally, the expression levels of TRPS1, EIF3S3 and MYC were measured in freshly frozen clinical samples of benign prostate hyperplasia (BPH), as well as untreated and hormone-refractory prostate carcinoma. The TRPS1 and MYC expression levels were similar in all prostate tumour groups, whereas EIF3S3 expression was higher (P=0.029) in prostate carcinomas compared to BPH. The data suggest that the expression of EIF3S3 is increased in prostate cancer, and that one of the mechanisms underlying the overexpression is the amplification of the gene.
Assuntos
Neoplasias da Mama/genética , Proteínas de Ligação a DNA , Fator de Iniciação 3 em Eucariotos/genética , Dosagem de Genes , Genes myc/fisiologia , Proteínas de Neoplasias/genética , Neoplasias da Próstata/genética , Neoplasias da Mama/metabolismo , Cromossomos Humanos Par 8/genética , Sondas de DNA/genética , DNA de Neoplasias/genética , DNA de Neoplasias/metabolismo , Fator de Iniciação 3 em Eucariotos/metabolismo , Feminino , Amplificação de Genes/genética , Humanos , Hibridização in Situ Fluorescente , Masculino , Proteínas de Neoplasias/metabolismo , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/metabolismo , Neoplasias Hormônio-Dependentes/genética , Neoplasias Hormônio-Dependentes/metabolismo , Hiperplasia Prostática/genética , Hiperplasia Prostática/metabolismo , Neoplasias da Próstata/metabolismo , RNA Neoplásico/genética , RNA Neoplásico/metabolismo , Proteínas Repressoras , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Transcrição , Células Tumorais CultivadasRESUMO
Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that regulates the expression of genes associated with adaptation to reduced oxygen pressure. Increased expression of HIF-1alpha gene (HIF1A) has been found in the majority of prostate carcinomas. In addition, the PC-3 prostate cancer cell line has been shown to express the gene even under normoxic conditions. By comparative genomic hybridization (CGH), we have earlier shown that the PC-3 cell line contains a high-level amplification in the chromosomal region harboring the HIF1A gene. Here, we first fine mapped the gene to locus 14q23 by fluorescence in situ hybridization (FISH). The gene was then shown to be highly amplified in the PC-3 cell line. Subsequently, the copy number of the HIF1A gene was studied in 5 other prostate cancer cell lines (LNCaP, DU-145, NCI-H660, Tsu-Pr, JCA-1) and in 117 prostate tumors representing both hormone-dependent and -refractory disease as well as primary and metastatic lesions. No high-level amplifications of the HIF1A gene were found. Additional copies of the gene were seen in all of the cell lines and in 36% of the tumors. There was no association between the tumor type and the copy number alterations of the gene. In conclusion, high-level amplification of the HIF1A gene may explain the overexpression of the gene in the PC-3 prostate cancer cell line. However, such high-level amplification seems to be very rare in prostate cancer.
Assuntos
Mapeamento Cromossômico , Cromossomos Humanos Par 14/genética , Proteínas de Ligação a DNA/genética , Sequências Hélice-Alça-Hélice/genética , Proteínas Nucleares/genética , Neoplasias da Próstata/genética , Fatores de Transcrição/genética , Proteínas de Ligação a DNA/metabolismo , Amplificação de Genes , Dosagem de Genes , Humanos , Fator 1 Induzível por Hipóxia , Subunidade alfa do Fator 1 Induzível por Hipóxia , Hibridização in Situ Fluorescente , Masculino , Proteínas Nucleares/metabolismo , Hibridização de Ácido Nucleico , Células Tumorais CultivadasRESUMO
The expression level of the androgen receptor (AR) gene in androgen-dependent and -independent prostate cancer was determined by using real-time quantitative reverse transcription-PCR assay. Eight benign prostate hyperplasias, 33 untreated and 13 hormone-refractory locally recurrent carcinomas, as well as 10 prostate cancer xenografts, were analyzed. All hormone-refractory tumors expressed AR and showed, on average, 6-fold higher expression than androgen-dependent tumors or benign prostate hyperplasias (P < 0.001). Four of 13 (31%) hormone-refractory tumors contained AR gene amplification detected by fluorescence in situ hybridization. Androgen-independent tumors with gene amplification expressed, on average, a 2-fold higher level of AR than the refractory tumors without the gene amplification. Two xenografts (LuCaP 35 and 69) showed amplification and high-level expression of the AR gene. These xenografts are the first prostate cancer model systems containing the gene amplification. The findings demonstrate that AR is highly expressed in androgen-independent prostate cancer, suggesting that the AR signaling pathway is important in the progression of prostate cancer during endocrine treatment. The two xenografts with the AR gene amplification will enable studies evaluating the functional significance of the amplification and development of new treatment strategies based on high-level expression of AR.
