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Biomedical subjects

R Chui

Publications and source records attributed to R Chui.

5 recordsLinked to original sources
PubMed2000

Frequent methylation of estrogen receptor in prostate cancer: correlation with tumor progression.

Prior studies have shown that the estrogen receptor (ER) gene is down-regulated in prostate cancer, but the mechanism of its inactivation is not known. We hypothesize that inactivation of the ER gene in prostate cancer is through promoter methylation. To test this hypothesis, we investigated the methylation status of the ER gene in prostate cancer cell lines, prostate cancer, and benign prostatic hyperplasia (BPH) tissues samples using the bisulfite genomic sequencing method. Our results show that the ER gene promoter was methylated in 100% (six of six) of the prostate cancer cell lines tested and all were accompanied by loss of ER mRNA expression. Treatment of these cell lines with demethylating agent 5-aza-2'-deoxycytidine restored ER mRNA expression in all of the ER-negative cell lines. In addition, elevated expression of DNA methyltransferase mRNA was found in all of the prostate cancer cell lines. Of the prostate tissue samples analyzed, 60% (6 of 10) in the BPH samples, 80% (8 of 10) in the low-grade cancer samples (grades I and II), and 95% (20 of 21) in the high-grade cancer samples (grades III-V) exhibited promoter methylation of the ER gene. The overall methylation levels in the cancer samples were higher than that in the BPH samples. The differences between the high-grade cancer samples and BPH samples were significant at all CpG sites. Only at three CpG sites were the differences significant between the low-grade cancer samples and BPH samples. This study presents the first evidence that ER gene is transcriptionally inactivated by DNA methylation in prostate cancer. Our data suggest that ER may be involved in the pathogenesis of prostate cancer, as well as BPH.

DNA (Cytosine-5-)-Methyltransferase 1↗
PubMed1999

Differential gene expression of growth factors in young and old rat penile tissues is associated with erectile dysfunction.

The molecular mechanisms of erectile dysfunction with aging are unclear. Recent studies have suggested that growth factors may play a role in the etiology of erectile dysfunction. This present study was designed to test the hypothesis that gene expression of various growth factors such as TGF alpha, TGF beta 1, TGF beta 2, TGF beta 3, IGF and NGF modulate with aging in rat penile tissues. For this purpose, total RNA was extracted from young and old rat penile tissues and the gene expression for these growth factors was determined by differential reverse-transcriptase-polymerase chain reaction (RT-PCR) using specific oligonucleotide primers. mRNA levels of growth factors were quantified by using beta-actin as an internal standard. The results of these experiments suggest that: (1) young and old rat penile tissues expressed mRNA transcripts for TGF alpha, TGF beta 1, TGF beta 2, TGF beta 3, IGF and NGF; (2) TGF beta 1 gene expression was significantly increased in old rat penile tissues as compared to young; (3) mRNA transcripts for NGF and TGF beta 3 were significantly lower in old rat penile tissues as compared to young; and (4) TGF alpha, TGF beta 2 and IGF mRNA expression did not change in young and old rat penile tissues. These results suggest that the differential gene expression for various growth factors in young and old rat penile tissues may be important in understanding the pathophysiology of erectile dysfunction associated with aging.

Aging↗
PubMed1996

Differential gene expression of transforming growth factors alpha and beta, epidermal growth factor, keratinocyte growth factor, and their receptors in fetal and adult human prostatic tissues and cancer cell lines.

OBJECTIVES: Recent studies have shown that growth factors may play a role in the etiology of benign prostatic hyperplasia (BPH) and prostatic carcinoma. Several growth factors have been reported to be expressed by prostatic tissues, but these growth factors have never been examined in human fetal prostate and compared with adult prostates and cancer cell lines. The present study was designed to investigate the messenger ribonucleic acid (mRNA) expression of transforming growth factor (TGF)-alpha, TGF-beta 1, TGF-beta 2, TGF- beta 3, keratinocyte growth factor (KGF), epidermal growth factor (EGF), EGF receptor (EGF-R), and KGF receptor (KGF-R) in human fetal and adult prostatic tissues and cancer cell lines by reverse-transcriptase-polymerase chain reaction-(RT-PCR) using specific oligonucleotide primers. METHODS: Total RNA was extracted from human fetal and adult prostates (BPH tissues) and cancer cell lines. The gene expression of these growth factors and their receptors was determined by RT-PCR using specific oligonucleotide primers. RESULTS: The results of these experiments suggest that: (1) human fetal prostate expressed mRNA transcripts for TGF-alpha, TGF-beta 1, TGF-beta 2, TGF-beta 3, and EGF. However, KGF, KGF-R, and EGF-R mRNA were not expressed by human fetal prostate; (2) human adult prostate (BPH tissues) showed mRNA transcripts for all growth factors and their receptors except KGF-R; (3) human BPH-1 cell lines expressed mRNA transcripts for TGF-alpha, TGF-beta 1, TGF-beta 2, TGF-beta 3, EGF, and KGF-R, but not for EGF-R and KGF growth factors; (4) human primary prostate cancer cell line (ND-1) showed mRNA transcripts for all growth factors except EGF and KGF; and (5) human prostate cancer cell lines (LNCaP, DU-145, PC-3) expressed mRNA transcripts for all growth factors except KGF, which was absent in all cell lines. However, KGF-R mRNA was absent in the PC-3 prostate cancer cell line. CONCLUSIONS: These results suggest that the differential gene expression for various growth factors and their receptors in human fetal and adult prostatic tissues and cancer cell lines may be important in understanding the role of these factors in the pathophysiology of prostatic diseases.

Adult↗
PubMed1982

Otitis media.

Dysfunction of the eustachian tube is the underlying problem in all types of otitis media. Systemic antibiotics and careful follow-up are the treatment of choice for acute suppurative otitis media, whereas topical antibiotics with saline irrigation are used in patients with a chronic condition. Myringotomy and tube insertion may be required in patients with secretory otitis media that does not undergo spontaneous resolution.

Acute Disease↗