Helga Engi

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Phospho-glycoprotein (P-gp) is a polytopic plasma membrane protein whose overexpression causes multidrug resistance (MDR) responsible for the failure of cancer chemotherapy. P-gp 170 is a member of the ATP-binding cassette (ABC) transporter superfamily and has two potentially interesting regions for drugs interfering with its efflux function, namely the(More)
Many of the herbal extracts used in the Chinese clinical medical routine inhibit the growth of tumor cells. In the present work, extracts of 12 selected herbs were prepared with methanol, chloroform, ethyl acetate and water, and the effects of these on the multidrug resistance (MDR) and P-glycoprotein of mouse lymphoma cells transfected with the human mdr1(More)
Human cytomegalovirus (CMV) preferentially infects tumor tissues and the accumulated CMV immediate-early (IE) antigen may lead to tumor promotion and progression. The development of strategies to inhibit human CMV IE antigen expression and/or function is an important goal to prevent and treat certain forms of cancers associated with human CMV. The aim of(More)
The multidrug resistance (MDR) proteins that belong to the ATP-binding cassette superfamily such as P-glycoprotein (P-gp) and MRP1, are present in a majority of human tumors and constitute an important cause of therapeutic failure. Selective inhibitors of the MDR-efflux proteins may improve the effectiveness of cancer chemotherapy. Their mechanism of action(More)
Bacteria and cancer cells develop resistance to more than one agent as a consequence of being exposed to ineffective levels of the agent for a prolonged period of time. The resistance of these cells is mediated by over-expressed efflux pumps that have the ability to extrude a large variety of unrelated chemicals. This review discusses the main types of(More)
BACKGROUND The multidrug resistance (MDR) proteins are present in a majority of human tumours. Their activity is important to understand the chemotherapeutic failure. A search for MDR-reversing compounds was conducted among various Betti-base derivatives of tylosin. METHODS Here, we evaluate the in vitro and in vivo P-glycoprotein (P-gp)-modulating(More)
The ability of 11 chalcones with 3,4,5-trimethoxy substitution on ring A to inhibit the transport activity of P-glycoprotein was studied. Flow cytometry was applied in multidrug-resistant human mdr1 gene-transfected mouse lymphoma cells (L 5178 Y). The reversal of multidrug resistance (MDR) was investigated by measuring the accumulation of rhodamine-123 in(More)
Aspergillus tubingensis isolates collected from distant geographic areas were earlier classified into six groups on the basis of the mtDNA RFLP variability they exhibited (mtDNA types 2a-2f). In the present work, we investigated the reason for the intraspecific mtDNA variability and we describe here how this fungus, with a relatively small mitochondrial(More)
The development of strategies intended to inhibit human cytomegalovirus (HCMV) immediate-early (IE) antigen expression is an important goal in research designed to prevent and treat certain forms of cancer. The aim of this study was to identify potent IE antigen-targeting natural compounds as antitumor promoters in an in vitro model of tumor promotion.(More)
The ability of phenothiazine derivatives to inhibit the transport activity of P-glycoprotein in resistant mouse lymphoma and MDR/COLO 320 cells was studied. A rhodamine 123 efflux from the above-mentioned neoplastic cells in the presence of tested compounds was examined by flow cytometry. Two of the phenothiazine derivatives, namely perphenazine and(More)