Anwar Husain

University of Louisville, Louisville, KY, United States

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Publications (5)14.19 Total impact

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    ABSTRACT: Pediatric pharmacogenetic studies have the potential to improve the quality of medical care for children. The pediatric population presents a unique pharmacogenetic challenge as children have the additional complexity of ontological phenotypes that impact their drug response. Prescribing medications in children has historically been largely empirical, but utilization of pharmacogenetic information will allow pediatricians to gain key information regarding which patients are best suited for a particular therapeutic agent and which patients may be at risk for serious potentially life-threatening complications from standard treatment regimens. Although large, prospective, multisite investigators are still needed, we illustrate selective clinical examples of the pharmacogenetics for treatment of transplantation, asthma, leukemia and attention-deficit hyperactivity disorder in pediatric patients.
    Pharmacogenomics 11/2007; 8(10):1403-11. · 3.86 Impact Factor
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    ABSTRACT: Arylamine N-acetyltransferase 1 (NAT1) plays an important role in the biotransformation of xenobiotics, and genetic variants have been implicated in susceptibility to cancer and birth defects. A specific and quantitative reverse transcription-polymerase chain reaction assay for transcription from the major NAT1 promoter detected high expression with limited variability in human tissues. A 213-base pair (bp) minimal promoter was identified by transfection of luciferase reporter constructs into MCF-7 and HepG2 cell lines. Alignment of the 213-bp region with paralogous and orthologous promoters revealed two conserved region segments, one of which overlaps a 16-bp perfect palindrome. Transfection of luciferase constructs with artificial mutations in the minimal promoter defined two sites important for promoter function. One of these sites included a close match to the Sp1 transcription factor binding consensus sequence. Electrophoretic mobility shift assays (EMSAs), followed by competitive and supershift analyses, confirmed the Sp1 binding. Mutation of the highly conserved portion of the 16-bp palindrome reduced promoter activity more than 3-fold, and an EMSA shift was detected with an oligonucleotide, 200L29, which spans this segment. The 200L29 EMSA shift could not be competed by consensus Sp1 or AP-2 oligonucleotides, and may represent binding of a transcription factor that is common to N-acetyltransferase genes in humans and other species.
    Drug Metabolism and Disposition 10/2007; 35(9):1649-56. · 3.36 Impact Factor
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    ABSTRACT: Human N-acetyltransferase 2 (NAT2) genetic polymorphism is associated with drug toxicity and/or carcinogenesis in various tissues. Knowledge of NAT2 gene structure and expression is critical for understanding these associations. Previous findings suggest that human NAT2 expression is highest in liver and gut but expressed at functional levels in other tissues. A sensitive and specific TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR) assay with intron-spanning primers was developed and used, together with a second TaqMan RT-PCR assay based on amplification of a NAT2 open reading frame (ORF) exon segment, to measure NAT2 mRNA in 29 different human tissues. Cap-dependent amplification of mRNA 5' termini and review of public database information were done to more precisely define the NAT2 promoter(s) and to validate the quantitative RT-PCR assay design. The great majority (40/41) of NAT2 liver cDNAs had 5' termini between 8682 and 8752 nucleotides upstream of the NAT2 ORF exon, and 34 of 40 5' termini were at the -8711 and -8716 adenines. All 59 NAT2 cDNAs with 5' termini in this vicinity, including 40 of the liver isolates and 19 cDNAs in public databases from liver and other sources, showed direct splicing to the ORF exon, with no other noncoding exon detected. NAT2 mRNA was highest in liver, small intestine, and colon and was readily detected in most other tissues, albeit at much lower levels. NAT2 expression in diverse human tissues provides further mechanistic support underlying associations between NAT2 genetic polymorphism, drug toxicity, and/or chemical carcinogenesis.
    Drug Metabolism and Disposition 06/2007; 35(5):721-7. · 3.36 Impact Factor
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    ABSTRACT: Variable expression of human arylamine N-acetyltransferase 1 (NAT1) due to genetic polymorphism, gene regulation or environmental influences is associated with individual susceptibility to various cancers. Recent studies of NAT1 transcription showed that most mRNAs originate at a promoter, P1, located 11.8 kb upstream of the single open reading frame (ORF) exon. We have now characterized an alternative NAT1 promoter lying 51.5 kb upstream of the NAT1 ORF. In the present study, analysis of human RNAs representing 27 tissue types by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantitative RT-PCR showed the upstream 51.5 kb promoter, designated P3, to be most active in specific tissues, including kidney, liver, lung, and trachea. All NAT1 P3 mRNAs included 5'-untranslated region (5'-UTR) internal exons of 61 and 175 nucleotides in addition to the 79 nucleotide 5'-UTR exon present in P1 mRNA. CAP-dependent amplification of 5'-P3 mRNA termini defined an 84 bp transcription start region in which most start sites are centrally clustered. The hepatoma-derived HepG2 cell line expressed a high level of P3 mRNA with the same spliced structure and start site pattern as found in normal tissues. A 435-bp minimal promoter was defined by transfection of HepG2 with luciferase expression constructs containing genomic fragments from the P3 start region. These findings imply a fundamental role for P3 in NAT1 regulation and define additional regions for genetic polymorphisms associated with enhanced cancer risk.
    Pharmacogenetics and Genomics 08/2006; 16(7):515-25. · 3.61 Impact Factor
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    ABSTRACT: Some carcinogens that initiate rat mammary cancer are substrates of human N-acetyltransferase 1 (NAT1) and variation in NAT1 activity due to environmental or genetic causes may influence human susceptibility to breast cancer. One unexplored potential cause of NAT1 expression variation is polymorphism of transcriptional control sequences. However, the location of the major NAT1 transcription control site is uncertain because earlier publications and current databases report different cDNA structures. To resolve this discrepancy, we used CAP-dependent cDNA cloning to identify 5' ends of NAT1 mRNAs from breast and MCF-7, a mammary adenocarcinoma cell line. Most transcription initiates in a 49-bp region located 11.8 kb upstream of the coding exon. A 79-bp exon located 2.5 kb upstream of the coding exon was found in all 41 of the independent NAT1 cDNA products. Seven of these 41 cDNAs also included other non-coding exons. The structures of NAT1 cDNAs in public databases, as obtained from diverse tissues, reflect a transcription pattern similar to that demonstrated in breast and MCF-7. Genomic fragments spanning the major start region were cloned into a luciferase vector and expressed in MCF-7. Promoter activities were 190-490-fold higher than the vector control and 30-80-fold higher than for a fragment immediately upstream of the coding exon. Our results demonstrate that, in breast, and likely also in other tissues, the major NAT1 mRNA is transcribed from a strong promoter located 11.8 kb upstream of the translated exon, and the mature spliced mRNA includes at least one additional non-coding exon.
    Pharmacogenetics 08/2004; 14(7):397-406.

Publication Stats

92 Citations
53 Downloads
312 Views
14.19 Total Impact Points

Institutions

  • 2004–2007
    • University of Louisville
      • Department of Pharmacology and Toxicology
      Louisville, KY, United States