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Frequency of C3435T single nucleotide MDR1 genetic polymorphism in an Asian population: phenotypic-genotypic correlates.

ABSTRACT: AIMS: To investigate the frequency of the single nucleotide polymorphism C3435T in exon 26 of the MDR1 gene in Asians and to determine the functional significance of this SNP with the clinical pharmacokinetics of oral cyclosporin (Neoral) in 10 stable heart transplant patients. METHODS: The MDR1 C3435T polymorphism was investigated in 290 healthy Asian subjects (98 Chinese, 99 Malays and 93 Indians). We also compared the MDR1 polymorphism between the Asian population studied here and the published data on Africans and Caucasians. The clinical relevance of this SNP on oral bioavailability of a known P-gp substrate, cyclosporin, was assessed in 10 stable Chinese heart transplant patients. RESULTS: The homozygous TT genotype was observed in 32%, 28% and 43% of Chinese, Malays and Indians. The homozygous CC genotype was found in 25% of Chinese and Malays compared with 18% of Indians. The Indians had a lower frequency of the C allele [0.38 (0.31-0.45)] compared with the Chinese [0.46 (0.39-0.53)] and Malays [0.48 (0.42-0.55)]. Chi-squared test showed that the distribution of allele frequencies between the Malays and Indians differed significantly (P = 0.04). In this Asian population, the overall distribution of genotypes (CC, CT and TT) and allele frequencies were significantly different from those in Africans (P < 0.001). The results were also significant when the Chinese, Malays and Indians were compared separately with the African group (P < 0.001). Compared with the Caucasian data, the overall distribution of genotype and allele frequencies in the Asian population were also significantly different (P < or = 0.05). However, when each Asian ethnic group was compared separately with the Caucasians, only the Indians were found to be significantly different (P < or = 0.004). Genotypic-phenotypic correlations of this SNP were assessed in 10 stable Chinese heart transplant patients. The median AUC(0,4 h) was 11% lower in patients with CC genotype compared with subjects with TT genotype. However, the interpatient variability in AUC(0,4 h) was high in patients, especially in those with CC genotype. CONCLUSIONS: The distribution of the SNP C3435T in exon 26 in the Chinese and Malay population was found to be similar to the Caucasians whereas the Indians were different. The Asian population also differed significantly from the African and Caucasian population in the distribution of the C3435T SNP. The low frequency of the T allele in the Indian population implies lower expression of P-gp and may have important therapeutic and prognostic implications for use of P-gp dependent drugs in individuals of Indian origin.

SUBMITTER: Balram C

PROVIDER: S-EPMC1884331 | biostudies-other | 2003 Jul

REPOSITORIES: biostudies-other

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Frequency of C3435T single nucleotide MDR1 genetic polymorphism in an Asian population: phenotypic-genotypic correlates.

Balram C C Sharma A A Sivathasan C C Lee Edmund J D EJ

British journal of clinical pharmacology 20030701 1

<h4>Aims</h4>To investigate the frequency of the single nucleotide polymorphism C3435T in exon 26 of the MDR1 gene in Asians and to determine the functional significance of this SNP with the clinical pharmacokinetics of oral cyclosporin (Neoral) in 10 stable heart transplant patients.<h4>Methods</h4>The MDR1 C3435T polymorphism was investigated in 290 healthy Asian subjects (98 Chinese, 99 Malays and 93 Indians). We also compared the MDR1 polymorphism between the Asian population studied here an ...[more]

PMID: 12848778

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Project description:To sum up our results, we managed to isolate a reproducible SP cell fraction of human gastric carcinoma cell lines for the first time. Those cells differed from the rest of the population regarding morphology and biological behaviour. They had the ability to build a population resembling the basic tumor population and therefore performed differenziation and asymmetric cell division. SP cells expressed potential stem cell markers like musashi 1 and Cd133 and also showed a high expression of genes that encode for stem cell properties. The so identified phenotypic and genetic factors showed a variable expression in tumor samples of patient series and might be applicable as prognostic factors in the diagnosis of gastric carcinoma. Aims: The side population (SP) of tumor cell lines shares characteristics with tumor stem cells. In this study we phenotypically and genotypically characterized the SP of gastric cancer cell lines. Methods: The SP was obtained from MKN45- and AGS-gastric cancer cells using Hoechst 33342 staining and fluorescence-activated cell sorting (FACS). SP cells were subsequently studied morphologically (cytology, immunocytochemistry), on the transcriptional level (gene array) and in cell culture (recultivation assays). Genes differentially expressed in the SP cells were finally searched by immunohistochemistry in neoplastic and non-neoplastic gastric tissue from gastric cancer patients. Results: The SP was reproducibly obtained from gastric cancer cell lines. The SP cells were smaller and rounder then non-SP cells. SP cells self-renewed in re-cultivation experiments and differentiated into SP- and non-SP cells. Re-cultivated SP- and non-SP cells showed distinct phenotypes in culture regarding cell shape and colony-formation. SP cells had increased levels of the stem cell markers CD133 and Musashi 1. Transcriptional analyses demonstrated that SP cells express genes that encode for stem cell properties like FZD7, HEY1, SMO and ADAM17. Finally we detected the transcripts of these genes in tissue samples from patients with gastric cancer. Conclusions: Human gastric cancer cell lines enclose a phenotypically and genotypically distinct cell population with tumor stem cell features. Phenotypical characteristics of this distinct cell population are also present in gastric cancer tissue.

Project description:BackgroundGenomic analysis has revealed extensive contamination among laboratory-maintained microbes including malaria parasites, Mycobacterium tuberculosis and Salmonella spp. Here, we provide direct evidence for recent contamination of a laboratory schistosome parasite population, and we investigate its genomic consequences. The Brazilian Schistosoma mansoni population SmBRE has several distinctive phenotypes, showing poor infectivity, reduced sporocysts number, low levels of cercarial shedding and low virulence in the intermediate snail host, and low worm burden and low fecundity in the vertebrate rodent host. In 2021 we observed a rapid change in SmBRE parasite phenotypes, with a ~10x increase in cercarial production and ~4x increase in worm burden.MethodsTo determine the underlying genomic cause of these changes, we sequenced pools of SmBRE adults collected during parasite maintenance between 2015 and 2023. We also sequenced another parasite population (SmLE) maintained alongside SmBRE without phenotypic changes.ResultsWhile SmLE allele frequencies remained stable over the eight-year period, we observed sudden changes in allele frequency across the genome in SmBRE between July 2021 and February 2023, consistent with expectations of laboratory contamination. (i) SmLE-specific alleles rose in the SmBRE population from 0 to 41-46% across the genome between September and October 2021, documenting the timing and magnitude of the contamination event. (ii) After contamination, strong selection (s = ~0.23) drove replacement of low fitness SmBRE with high fitness SmLE alleles. (iii) Allele frequency changed rapidly across the whole genome, except for a region on chromosome 4 where SmBRE alleles remained at high frequency.ConclusionsWe were able to detect contamination in this case because SmBRE shows distinctive phenotypes. However, this would likely have been missed with phenotypically similar parasites. These results provide a cautionary tale about the importance of tracking the identity of parasite populations, but also showcase a simple approach to monitor changes within populations using molecular profiling of pooled population samples to characterize fixed single nucleotide polymorphisms. We also show that genetic drift results in continuous change even in the absence of contamination, causing parasites maintained in different labs (or sampled from the same lab at different times) to diverge.

Dataset Information

Frequency of C3435T single nucleotide MDR1 genetic polymorphism in an Asian population: phenotypic-genotypic correlates.

Publications

Frequency of C3435T single nucleotide MDR1 genetic polymorphism in an Asian population: phenotypic-genotypic correlates.

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