Genomic organization of an intron-containing sperm protein 17 gene (Sp17-1) and an intronless pseudogene (Sp17-2) in humans: a new model

Differentially expressed genes in the prostate cancer cell line LNCaP after exposure to androgen and anti-androgen

Androgens play an important role in growth and maintenance of prostate cells. The actions of androgens are mediated by the androgen receptor (AR), a transcription factor member of the super-family of nuclear hormone receptors. Androgen regulated genes (ARGs) are potential markers for early diagnosis and treatment of prostate cancer patients. In the present study, we used DDRT-PCR (differential display reverse transcriptase polymerase chain reaction) technique in order to investigate differentially expressed genes in the prostate cancer cell line LNCaP after treatment with dihydrotestosterone and bicalutamide for 6, 24, and 48 hours. Fifty-five differentially expressed fragments were isolated, cloned, and sequenced. Sequencing analysis of these fragments revealed 56 different transcripts that showed homology to transcription factors, cell cycle regulators, metabolic enzymes, and hypothetical proteins. Among the differentially expressed genes, SPA17 and DDEF2 were further validated using quantitative real time RT-PCR (qPCR) in a series of 25 prostate tumor samples. The DDEF2 gene is involved in adhesion and cell migration of monocytes, and the SPA17 gene might be involved in cellular signal transduction. The transcripts of both, SPA17 and DDEF2 genes, showed altered pattern of expression in the group of prostate tumors analyzed by qPCR. The differentially expressed genes identified in this study might provide new insights into the androgen signaling pathways in prostate cells.

Genomic characterization and physical mapping of two fucosyltransferase genes inMedicago truncatula

Fucosyltransferases catalyse fucose transfer onto oligosaccharides. Two fucosylated structures have been identified in plants: the α1,4-fucosylated Lewis-a epitope and the α1,3-fucosylated core. Here we report the cloning, genomic characterization, and physical mapping of two genes encoding proteins similar to α1,4-fucosyltransferase (EC 2.4.1.65, MtFUT1) and α1,3-fucosyltransferase (EC 2.4.1.214, MtFUT2) in Medicago truncatula. Analysis of the genomic organization of the fucosyltransferase genes in M. truncatula, revealed the presence of two genomic variants of the MtFUT1 gene coding sequence, one containing a single intron and the other intronless, whereas in MtFUT2, the gene coding region is interrupted by four introns. Using for the first time fluorescence in situ hybridization (FISH) to physically map fucosyltransferase genes in plants, this study reveals a high genomic dispersion of these genes in Medicago. The MtFUT1 genes are mapped on chromosomes 4, 7, and 8, colocalizing on three of the five MtFUT2 loci. Chromosomes 1 and 5 carry the additional MtFUT2 loci. Moreover, the intensity of the FISH signals reveals marked differences in the number of gene copies per locus for both genes. Simultaneous mapping of rRNA genes on chromosome 5 shows that several MTFUT2 gene loci are inserted within the rDNA array. Insertions of coding DNA sequences into the rDNA repeats were never reported to date.Key words: core α1,3-fucosyltransferase gene, α1,4-fucosyltransferase gene, genomic organization, in situ hybridization, Medicago truncatula.

Combined real time PCR and immunohistochemical evaluation of sperm protein 17 as a cancer-testis antigen

We previously identified sperm protein 17 (Sp17) as a normal testicular protein aberrantly expressed in a proportion of multiple myeloma (MM). However, recent studies have generated controversies on the normal tissue expression of Sp17 and whether or not it is a suitable target for immunotherapy. In this study, we have used a combination of real time polymerase chain reaction and immunohistochemistry on a large panel of normal tissues. Although Sp17 transcripts could be detected in some normal tissues, the levels of expression were <2% of those in normal testis. In contrast, Sp17+ myeloma cells expressed 3-18% of normal testis levels of Sp17 transcript. Immunohistochemistry using two Sp17 murine monoclonal antibodies, each directed at a non-overlapping B-cell epitope, showed Sp17 protein to be expressed only in testis and not any other normal tissues. Specificity of binding of the antibodies to testis was also confirmed in competitive binding assays. Our results therefore further suggest Sp17 as a cancer-testis antigen in MM and support its suitability as a target for immunotherapy.

Sp17 gene expression in myeloma cells is regulated by promoter methylation

The mechanisms underlying sperm protein 17 (Sp17) gene expression in myeloma cells remained unclear. Using reverse transcription–polymerase chain reaction (RT–PCR), Sp17 transcripts were detected in ARK-B, ARP-1, RPMI-8226 and KMS-11 but not in H929, IM-9, MM1-R and U266 cells. Using a panel of primer pairs in methylation-sensitive PCR to amplify overlapping gene segments, our screening studies showed that the HpaII sites at −359 and −350 are involved in the regulation of Sp17 gene expression. To confirm the differences in methylation status between Sp17-positive and Sp17-negative cell lines, KMS-11 cells (Sp17-positive) and IM-9 cells (Sp17-negative) were subjected to the more accurate method of bisulphite conversion. KMS-11 cells were more hypomethylated at these HpaII sites of exon 1 compared to IM-9 cells, indicating the association of hypomethylated promoter with Sp17 gene expression. In addition, the level of methylation at other CpG sites within the promoter sequence was also higher in IM-9 than KMS-11. Exon 1 was cloned into a reporter vector, pCAT^*3 Enhancer. Chloramphenicol acetyl transferase (CAT) activity was restored in cells transfected with the recombinant plasmid, indicating the promoter function of exon 1. Exposure of Sp17-negative cell lines to the hypomethylating agent, 5-azacytidine, resulted in the upregulation of Sp17 gene expression. Our results therefore provide evidence for the regulation of Sp17 gene expression by promoter methylation.