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      Doxorubicin-conjugated dexamethasone induced MCF-7 apoptosis without entering the nucleus and able to overcome MDR-1-induced resistance

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          Doxorubicin (DOX) is the most widely used chemotherapeutic agent that has multimodal cytotoxicity. The main cytotoxic actions of DOX occur in the nucleus. The emergence of drug-resistant cancer cells that have the ability to actively efflux DOX out of the nucleus, and the cytoplasm has led to the search for a more effective derivative of this drug.

          Materials and methods

          We created a new derivative of DOX that was derived via simple conjugation of the 3′ amino group of DOX to the dexamethasone molecule.


          Despite having a lower cytotoxic activity in MCF-7 cells, the conjugated product, DexDOX, exerted its actions in a manner that was different to that of DOX. DexDOX rapidly induced MCF-7 cell apoptosis without entering the nucleus. Further analysis showed that Dex-DOX increased cytosolic oxidative stress and did not interfere with the cell cycle. In addition, the conjugated product retained its cytotoxicity in multidrug resistance-1-overexpressing MCF-7 cells that had an approximately 16-fold higher resistance to DOX.


          We have synthesized a new derivative of DOX, which has the ability to overcome multidrug resistance-1-induced resistance. This molecule may have potential as a future chemotherapeutic agent.

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          Most cited references 29

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          P-glycoprotein: from genomics to mechanism.

          Resistance to chemically different natural product anti-cancer drugs (multidrug resistance, or MDR) results from decreased drug accumulation, resulting from expression of one or more ATP-dependent efflux pumps. The first of these to be identified was P-glycoprotein (P-gp), the product of the human MDR1 gene, localized to chromosome 7q21. P-gp is a member of the large ATP-binding cassette (ABC) family of proteins. Although its crystallographic 3-D structure is yet to be determined, sequence analysis and comparison to other ABC family members suggest a structure consisting of two transmembrane (TM) domains, each with six TM segments, and two nucleotide-binding domains. In the epithelial cells of the gastrointestinal tract, liver, and kidney, and capillaries of the brain, testes, and ovaries, P-gp acts as a barrier to the uptake of xenobiotics, and promotes their excretion in the bile and urine. Polymorphisms in the MDR1 gene may affect the pharmacokinetics of many commonly used drugs, including anticancer drugs. Substrate recognition of many different drugs occurs within the TM domains in multiple-overlapping binding sites. We have proposed a model for how ATP energizes transfer of substrates from these binding sites on P-gp to the outside of the cell, which accounts for the apparent stoichiometry of two ATPs hydrolysed per molecule of drug transported. Understanding of the biology, genetics, and biochemistry of P-gp promises to improve the treatment of cancer and explain the pharmacokinetics of many commonly used drugs.
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            Doxorubicin induces apoptosis in normal and tumor cells via distinctly different mechanisms. intermediacy of H(2)O(2)- and p53-dependent pathways.

            Doxorubicin (DOX), a widely used chemotherapeutic agent, exhibits cardiotoxicity as an adverse side effect in cancer patients. DOX-mediated cardiomyopathy is linked to its ability to induce apoptosis in endothelial cells and cardiomyocytes by activation of p53 protein and reactive oxygen species. We evaluated the potential roles of H(2)O(2) and p53 in DOX-induced apoptosis in normal bovine aortic endothelial cells and adult rat cardiomyocytes and in tumor cell lines PA-1 (human ovarian teratocarcinoma) and MCF-7 (human breast adenocarcinoma). Time course measurements indicated that activation of caspase-3 preceded the stimulation of p53 transcriptional activity in endothelial cells. In contrast, DOX caused early activation of p53 in tumor cells that was followed by caspase-3 activation and DNA fragmentation. These findings suggest that the transcriptional activation of p53 in DOX-induced apoptosis in endothelial cells may not be as crucial as it is in tumor cells. Further evidence was obtained using a p53 inhibitor, pifithrin-alpha. Pifithrin-alpha completely suppressed DOX-induced activation of p53 in both normal and tumor cell lines and prevented apoptosis in tumor cell lines but not in endothelial cells and cardiomyocytes. In contrast, detoxification of H(2)O(2), either by redox-active metalloporphyrin or overexpression of glutathione peroxidase, decreased DOX-induced apoptosis in endothelial cells and cardiomyocytes but not in tumor cells. This newly discovered mechanistic difference in DOX-induced apoptotic cell death in normal versus tumor cells will be useful in developing drugs that selectively mitigate the toxic side effects of DOX without affecting its antitumor action.
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              The anthracyclines: will we ever find a better doxorubicin?

               Carolyn Weiss (1992)
              The anthracyclines are the class of antitumor drugs with the widest spectrum of activity in human cancers, and only a few cancers (eg, colon cancer) are unresponsive to them. The first two anthracyclines were developed in the 1960s. Doxorubicin (DOX) differs from daunorubicin (DNR) only by a single hydroxyl group. This fact has spurred researchers worldwide to find analogs of DOX that have less acute toxicity, cause less cardiomyopathy, can be administered orally, and/or have different, or greater, antitumor efficacy. Five DOX/DNR analogs are marketed in other countries, and one (idarubicin) is available in the United States. None of these analogs have stronger antitumor efficacy than the original two anthracyclines, but there are some differences in toxicity. Methods have been fashioned to keep the peak plasma level of DOX muted to minimize cardiotoxicity, but the only apparently effective method available so far (prolonged drug infusion) is cumbersome. The bisoxopiperazine class of drugs (especially dexrazoxane) provides protection against anthracycline-induced cardiomyopathy and has much promise for helping mitigate this major obstacle to prolonged use of the anthracyclines. The DOX analogs being evaluated in the 1990s have been selected for their ability to overcome multidrug resistance in cancer cells. Thirty years after discovery of the anticancer activity of the first anthracycline, some means of reducing anthracycline toxicity have been devised. Current studies are evaluating increased doses of epirubicin to improve anthracycline cytotoxicity, while limiting cardiotoxicity, but at present DOX still reigns in this drug class as the one having the most proven cancerocidal effect.

                Author and article information

                Drug Des Devel Ther
                Drug Des Devel Ther
                Drug Design, Development and Therapy
                Drug Design, Development and Therapy
                Dove Medical Press
                01 August 2018
                : 12
                : 2361-2369
                [1 ]Molecular and Cellular Biology Unit, Department of Medicine, Lerdsin General Hospital, Bangkok, Thailand, kmanotham@ 123456hotmail.com
                [2 ]Medical Sciences Program, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
                [3 ]EST Laboratory, SS Manufacturing, Nonthaburi, Thailand
                [4 ]Research Division, National Cancer Institute, Bangkok, Thailand
                [5 ]Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
                [6 ]Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
                Author notes
                Correspondence: Krissanapong Manotham, Molecular and Cell Biology Unit, Department of Medicine, Lerdsin General Hospital, 190 Silom, Bang-Rak, Bangkok 10500, Thailand, Tel +66 2353 9710, Fax +66 2353 9711, Email kmanotham@ 123456hotmail.com
                © 2018 Chaikomon et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at https://www.dovepress.com/terms.phpand incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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