Biomedical subjects

Wolfgang Sadee

Publications and source records attributed to Wolfgang Sadee.

10 recordsLinked to original sources

PubMed2006

5-Aza-2'-deoxycytidine and depsipeptide synergistically induce expression of BIK (BCL2-interacting killer).

DNA methylation and histone acetylation are main epigenetic events regulating gene expression, serving as anticancer drug targets. A combination of the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine with the histone deacetylase inhibitor depsipeptide synergistically induces apoptosis. To characterize genes involved in this process, we measured expression of 376 apoptosis-related genes with microarrays after treatment with the two inhibitors alone or in combination. The pro-apoptotic BIK (Bcl2-interacting killer) was the only gene synergistically upregulated in all four cancer cell lines tested (A549, PC-3, TK-10, and UO-31). BIK induction was confirmed by RT-PCR and Western blots. Histone acetylation of the BIK promoter region increased with depsipeptide treatment but was not further affected by 5-aza-2'-deoxycytidine. In summary, synergistic upregulation of pro-apoptotic BIK-previously shown to suppress tumor growth-appears to play a critical role in anticancer effects of 5-aza-2'-deoxycytidine plus depsipeptide.

Acetylation↗

PubMed2006

Glucose uptake inhibitor sensitizes cancer cells to daunorubicin and overcomes drug resistance in hypoxia.

PURPOSE: A high-rate glycolysis is a fundamental property of solid tumors and is associated with an over-expression of glucose transporters and glycolytic enzymes. We hypothesize that over-expression of glucose transporters in tumors prevents apoptosis, promotes cancer cell survival, and confers drug resistance. Inhibition of glucose transporter will preferentially sensitize the anticancer effects of chemotherapeutic drugs to overcome drug resistance in hypoxia. METHODS: Glucose transporter expressions were detected in cancer tissues and NCI 60 cancer cells with immunostaining and DNA microarray. Glucose uptake was measured with 3H-2-deoxy-glucose. Cytotoxicity of daunorubicin (DNR) in combination of glucose inhibitor was detected by MTS assay under hypoxic condition. Early stage apoptosis was monitored with Annexin V-FITC staining. RESULTS: Immunostaining showed that GLUT1 was significantly increased in hypoxic regions of the human colon and breast tumors. The expression profiles of all glucose transporters in NCI 60 cancer cells exhibited distinct expression patterns. Phloretin exhibited more than 60% glucose uptake inhibition. Hypoxia conferred two to fivefold higher drug resistance in SW620 and K562 to DNR. Inhibition of glucose uptake by phloretin sensitized cancer cells to DNR for its anticancer activity and apoptosis to overcome drug resistance only under hypoxia. CONCLUSION: Cancer cells heavily rely on glucose transporters for glucose uptake to facilitate a high-rate glycolysis under hypoxia for their survival and drug resistance. Combination of glucose transporter inhibitors and chemotherapeutic drugs may provide a preferential novel therapeutic strategy to overcome drug resistance in hypoxia.

Apoptosis↗

PubMed2006

Protein therapeutics: new applications for pharmacogenetics.

Pharmacogenetic studies have traditionally focused on genes involved in processes that affect the pharmacokinetics of small-molecule drugs, such as drug metabolism. However, attention is shifting to the effects of genetic variations in drug targets and associated pathway components on drug responses. We describe how these variations are important for understanding differences in responses to the growing number of protein therapeutics that are entering clinical practice. Pharmacogenetic studies of these drugs are surveyed, and issues important to the success of such endeavours are discussed. As novel protein therapeutics are introduced, we anticipate that the use of pharmacogenetics will assume a key role in their development and clinical application.

Clinical Trials as Topic↗

PubMed2005

ABCB5-mediated doxorubicin transport and chemoresistance in human malignant melanoma.

Enhanced drug efflux mediated by ABCB1 P-glycoprotein and related ATP-binding cassette transporters is one of several mechanisms of multidrug resistance thought to impair chemotherapeutic success in human cancers. In malignant melanoma, its potential contribution to chemoresistance is uncertain. Here, we show that ABCB5, which functions as a determinant of membrane potential and regulator of cell fusion in physiologic skin progenitor cells, is expressed in clinical malignant melanoma tumors and preferentially marks a subset of hyperpolarized, CD133+ stem cell phenotype-expressing tumor cells in malignant melanoma cultures and clinical melanomas. We found that ABCB5 blockade significantly reversed resistance of G3361 melanoma cells to doxorubicin, an agent to which clinical melanomas have been found refractory, resulting in a 43% reduction in the LD50 from 4 to 2.3 micromol/L doxorubicin (P < 0.05). Our results identified ABCB5-mediated doxorubicin efflux transport as the underlying mechanism of resistance, because ABCB5 blockade significantly enhanced intracellular drug accumulation. Consistent with this novel ABCB5 function and mechanism in doxorubicin resistance, gene expression levels of the transporter across a panel of human cancer cell lines used by the National Cancer Institute for drug screening correlated significantly with tumor resistance to doxorubicin (r = 0.44; P = 0.016). Our results identify ABCB5 as a novel drug transporter and chemoresistance mediator in human malignant melanoma. Moreover, our findings show that ABCB5 is a novel molecular marker for a distinct subset of chemoresistant, stem cell phenotype-expressing tumor cells among melanoma bulk populations and indicate that these chemoresistant cells can be specifically targeted via ABCB5 to enhance cytotoxic efficacy.

AC133 Antigen↗

PubMed2004

Strategies and methods for research on sex differences in brain and behavior.

Female and male brains differ. Differences begin early during development due to a combination of genetic and hormonal events and continue throughout the lifespan of an individual. Although researchers from a myriad of disciplines are beginning to appreciate the importance of considering sex differences in the design and interpretation of their studies, this is an area that is full of potential pitfalls. A female's reproductive status and ovarian cycle have to be taken into account when studying sex differences in health and disease susceptibility, in the pharmacological effects of drugs, and in the study of brain and behavior. To investigate sex differences in brain and behavior there is a logical series of questions that should be answered in a comprehensive investigation of any trait. First, it is important to determine that there is a sex difference in the trait in intact males and females, taking into consideration the reproductive cycle of the female. Then, one must consider whether the sex difference is attributable to the actions of gonadal steroids at the time of testing and/or is sexually differentiated permanently by the action of gonadal steroids during development. To answer these questions requires knowledge of how to assess and/or manipulate the hormonal condition of the subjects in the experiment appropriately. This article describes methods and procedures to assist scientists new to the field in designing and conducting experiments to investigate sex differences in research involving both laboratory animals and humans.

Animals↗

PubMed2004

Polymorphisms affecting gene regulation and mRNA processing: broad implications for pharmacogenetics.

Functional polymorphisms that alter gene expression and mRNA processing appear to play a critical role in shaping human phenotypic variability. Intensive studies on polymorphisms affecting drug response have revealed multiple modes of altered gene function, frequently involving cis-acting regulatory sequence variants. Experimental and in silico methods have advanced the search for such polymorphisms, but considerable challenges remain. Here, a survey of polymorphisms in drug-related genes indicates that: (a) a substantial proportion of genetic variability still remains unaccounted for; (b) a majority of these genes harbors known regulatory polymorphisms; and (c) a portion of polymorphisms affect splicing and mRNA turnover. Pharmacogenetic optimiziation of individual drug therapy may require a complete understanding of all functional sequence variants in key genes. This review surveys known noncoding polymorphisms in genes encoding cytochrome P450s and other drug-metabolizing enzymes, drug transporters, and drug targets and receptors. Current methods and challenges associated with the identification and characterization of functional polymorphisms are also discussed.

Animals↗

PubMed2004

Transporter and ion channel gene expression after Caco-2 cell differentiation using 2 different microarray technologies.

mRNA expression profiles had previously been measured in Caco-2 cells (human colonic carcinoma cells) using either custom-designed spotted oligonucleotide arrays or Affymetrix GeneChip oligonucleotide arrays. The Caco-2 cells used were from different clones and were examined under slightly different culture conditions commonly encountered when Caco-2 cells are used as a model tissue for studying intestinal transport and metabolism in different laboratories. In this study, we compared gene expression profiles of Caco-2 cells generated with different arrays to assess the validity of conclusions derived from the 2 independent studies, with a focus on changes in transporter and ion channel mRNA expression levels on Caco-2 cell differentiation. Significant changes in expression levels upon differentiation were observed with 78 genes, with probes common to both arrays. Of these, 18 genes were upregulated and 36 genes were downregulated. The 2 arrays yielded discrepant results for 24 genes, showing significant changes upon differentiation. The results from the 2 arrays correlated well for genes expressed above average levels (r = 0.75, P < 0.01, n = 25) and poorly for genes expressed at low levels (r = 0.08, P > 0.05, n = 25). Overall correlation across the 2 platforms was r = 0.45 (P < 0.01) for the 78 genes, with similar results from both arrays. Despite differences in experimental conditions and array technology, similar results were obtained for most genes.

Caco-2 Cells↗

PubMed2003

Intra- and interindividual variabilities of valacyclovir oral bioavailability and effect of coadministration of an hPEPT1 inhibitor.

Variability in valacyclovir bioavailability and the potential for cephalexin-valacyclovir interaction were evaluated. The intraindividual acyclovir area under the concentration-time curve (AUC) varied minimally, whereas interindividual differences were substantial. Coadministration of the human peptide transporter 1 (hPEPT1) substrates valacyclovir and cephalexin minimally reduced the acyclovir AUC. These results suggest a stable valacyclovir absorption phenotype, significant interindividual variability, and minimal interaction between these hPEPT1 substrates.

Acyclovir↗

PubMed2002

Pharmacogenomics: the implementation phase.

Pharmacogenomics makes use of genetic and genomic principles to facilitate drug discovery and development, and to improve drug therapy. Its goal is to attain optimal therapy for the individual patient. This article analyzes current trends in pharmacogenomics and asks how this new science affects drug development in the pharmaceutical industry and the clinical use of drugs.

Chemistry, Pharmaceutical↗

PubMedDate not supplied

A pharmacoproteomics study of the cancer cell line EKVX using capillary-LC/MS/MS.

The chemotherapeutic agent camptothecin, 10-OH (CPT,10-OH), was shown to act synergistically with the epithelial growth factor receptor (EGFR) inhibitor (AG1478) against several transformed cell lines. To study the cellular response to these drugs, the non-small-cell lung carcinoma cell line, EKVX, was treated with these compounds either alone or in combination. We performed a proteomic analysis using capillary-HPLC coupled with electrospray ion trap mass spectrometry (capillary-LC-ESI/MS) of a tryptic digest to obtain a global protein profile of the EKVX cell line and identify changes in protein expression. The combination of AG1478 and CPT,10-OH showed synergistic cytotoxicity and also changed the expression of multiple proteins, while individual treatments showed a lesser effect on protein expression. Thus, the synergistic action of AG1478 and CPT,10-OH was reflected in altered protein profiles, showing that a proteomic analysis can serve to evaluate chemotherapeutic agents and their combinations.

Amino Acid Sequence↗