Biomedical subjects

Maria A Nagai

Publications and source records attributed to Maria A Nagai.

5 recordsLinked to original sources

PubMed2006

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.

Aged↗

PubMed2005

Large-scale transcriptome analyses reveal new genetic marker candidates of head, neck, and thyroid cancer.

A detailed genome mapping analysis of 213,636 expressed sequence tags (EST) derived from nontumor and tumor tissues of the oral cavity, larynx, pharynx, and thyroid was done. Transcripts matching known human genes were identified; potential new splice variants were flagged and subjected to manual curation, pointing to 788 putatively new alternative splicing isoforms, the majority (75%) being insertion events. A subset of 34 new splicing isoforms (5% of 788 events) was selected and 23 (68%) were confirmed by reverse transcription-PCR and DNA sequencing. Putative new genes were revealed, including six transcripts mapped to well-studied chromosomes such as 22, as well as transcripts that mapped to 253 intergenic regions. In addition, 2,251 noncoding intronic RNAs, eventually involved in transcriptional regulation, were found. A set of 250 candidate markers for loss of heterozygosis or gene amplification was selected by identifying transcripts that mapped to genomic regions previously known to be frequently amplified or deleted in head, neck, and thyroid tumors. Three of these markers were evaluated by quantitative reverse transcription-PCR in an independent set of individual samples. Along with detailed clinical data about tumor origin, the information reported here is now publicly available on a dedicated Web site as a resource for further biological investigation. This first in silico reconstruction of the head, neck, and thyroid transcriptomes points to a wealth of new candidate markers that can be used for future studies on the molecular basis of these tumors. Similar analysis is warranted for a number of other tumors for which large EST data sets are available.

Alternative Splicing↗

PubMed2004

A transcript finishing initiative for closing gaps in the human transcriptome.

We report the results of a transcript finishing initiative, undertaken for the purpose of identifying and characterizing novel human transcripts, in which RT-PCR was used to bridge gaps between paired EST clusters, mapped against the genomic sequence. Each pair of EST clusters selected for experimental validation was designated a transcript finishing unit (TFU). A total of 489 TFUs were selected for validation, and an overall efficiency of 43.1% was achieved. We generated a total of 59,975 bp of transcribed sequences organized into 432 exons, contributing to the definition of the structure of 211 human transcripts. The structure of several transcripts reported here was confirmed during the course of this project, through the generation of their corresponding full-length cDNA sequences. Nevertheless, for 21% of the validated TFUs, a full-length cDNA sequence is not yet available in public databases, and the structure of 69.2% of these TFUs was not correctly predicted by computer programs. The TF strategy provides a significant contribution to the definition of the complete catalog of human genes and transcripts, because it appears to be particularly useful for identification of low abundance transcripts expressed in a restricted set of tissues as well as for the delineation of gene boundaries and alternatively spliced isoforms.

Alternative Splicing↗

PubMed2003

Androgen receptor CAG repeat polymorphism in prostate cancer from a Brazilian population.

Shorter CAG repeats in the androgen receptor (AR) gene have been associated with increased prostate cancer risk. Aiming to investigate whether the AR CAG polymorphism is associated with an increased relative risk for prostate cancer in our population, genomic DNA from 133 prostate cancer patients and 279 healthy men controls were examined. We found no association between the AR CAG polymorphism and the relative risk of prostate cancer in white Brazilian individuals with a CAG repeat length </=21. Our results show that in the studied population the Asian-descendants have the highest, the white an intermediate and the black a tendency to the lowest CAG repeats rates. We observed a significant correlation between a lower number of CAG repeats and young age at diagnosis (P=0.034). This study is the first to investigate the association between the AR CAG repeat polymorphism and the relative risk of prostate cancer in the Brazilian population.

Aged↗

PubMed2003

Relaxation of imprinting of IGFII gene in juvenile nasopharyngeal angiofibromas.

IGFII and H19 genes are expressed only from one allele due to genomic imprinting, biallelic expression (loss of imprinting) being associated with the tumorigenic process of different types of tumors. The mechanism responsible for genomic imprinting is not yet determined, although DNA methylation has been considered the main genetic event for an imprinted mark. In the current study, the authors analyzed the imprinting status and expression levels of the IGFII and H19 genes in 27 cases of Juvenile Nasopharyngeal Angiofibroma (JNA) using RFLPs, RT-PCR, and Southern and Northern Blots. The authors found that four out of eight informative cases (50%) for ApaI/IFGII polymorphism showed biallelic expression of IFGII whereas none of the nine informative cases for the polymorphism showed biallelic expression of the H19 gene. Overexpression of IFGII was observed in 8 out of 22 cases (36.4%), and 7 out of 19 cases (36.8%) showed H19 overexpression. Hypomethylation was found only in the H19 gene in six out of eight cases analyzed. Therefore, our results demonstrate that alterations in the IFGII/H19 imprinted region occur in JNA.

Adolescent↗