ABSTRACT
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.
Subject(s)
Breast Neoplasms/genetics , DNA-Binding Proteins , Eukaryotic Initiation Factor-3/genetics , Gene Dosage , Genes, myc/physiology , Neoplasm Proteins/genetics , Prostatic Neoplasms/genetics , Breast Neoplasms/metabolism , Chromosomes, Human, Pair 8/genetics , DNA Probes/genetics , DNA, Neoplasm/genetics , DNA, Neoplasm/metabolism , Eukaryotic Initiation Factor-3/metabolism , Female , Gene Amplification/genetics , Humans , In Situ Hybridization, Fluorescence , Male , Neoplasm Proteins/metabolism , Neoplasm Recurrence, Local/genetics , Neoplasm Recurrence, Local/metabolism , Neoplasms, Hormone-Dependent/genetics , Neoplasms, Hormone-Dependent/metabolism , Prostatic Hyperplasia/genetics , Prostatic Hyperplasia/metabolism , Prostatic Neoplasms/metabolism , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Repressor Proteins , Reverse Transcriptase Polymerase Chain Reaction , Transcription Factors , Tumor Cells, CulturedABSTRACT
Prostate cancer is the most common male malignancy in the United States as well as in many European countries. It is curable as long as it is localized, but the invasion of prostate cancer and formation of metastasis turn it into a life-threatening disease. Urokinase-type plasminogen activator (uPA) is believed to play a key role in tissue degradation and cell migration under various normal and pathological conditions, including cancer invasion and metastasis. Increased expression of uPA has been reported in various malignancies including prostate cancer. However, the mechanisms of the overexpression have remained poorly understood. Here, we report increased copy number of uPA gene in 3 of 13 hormone-refractory prostate carcinomas, including 1 high-level amplification. Real-time quantitative reverse transcription-PCR showed that the increased expression of uPA coincided with the amplification of the gene in these tumors. Matrigel invasion assay showed that prostate cancer cell line PC-3, containing amplification of the uPA gene, was more sensitive to the urokinase inhibitor, amiloride, than DU145 or LNCaP cell lines, which do not have the amplification. The findings suggest that one of the mechanisms underlying the overexpression of the uPA is the amplification of the gene, which is associated with the increased invasive potential of the cells.
Subject(s)
Prostatic Neoplasms/pathology , Urokinase-Type Plasminogen Activator/genetics , Blotting, Northern , Gene Amplification , Humans , In Situ Hybridization, Fluorescence , Male , Nucleic Acid Hybridization , Prostatic Neoplasms/enzymology , Prostatic Neoplasms/genetics , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Tumor Cells, CulturedABSTRACT
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.
