Pharmaceutical Research

, Volume 24, Issue 9, pp 1618–1627 | Cite as

Enhanced Intercellular Retention Activity of Novel pH-sensitive Polymeric Micelles in Wild and Multidrug Resistant MCF-7 Cells

  • Ghazal Mohajer
  • Eun Seong Lee
  • You Han Bae
Research Paper



The purpose of this work was to demonstrate the advantage of using pH-sensitive polymeric mixed micelles (PHSM) composed of poly(l-histidine) (polyHis)/poly(ethylene glycol) (PEG) and poly(l-lactic acid) (pLLA)/PEG block copolymers with folate conjugation to increase drug retention in wild-type and MDR tumor cells.

Materials and Methods

Both wild-type and multidrug resistant (MDR) human breast adenocarcinoma (MCF-7) cell lines were used to investigate the accumulation and elimination of doxorubicin (DOX), PHSM with folate (PHSM/f), and pH-insensitive micelles composed of pLLA/PEG block copolymer with folate (PHIM/f).


Cells treated with PHSM/f showed decelerated elimination kinetics compared to cells treated with PHIM/f. MDR cells treated with drug-containing PHSM/f for 30 min retained 80% of doxorubicin (DOX) even after incubation for 24 h in the absence of drug. On the other hand, cells treated with drug-containing PHIM/f retained only 40% of DOX within the same period of time. Flow cytometry and confocal microscopy confirmed these results.


Cellular entry of the micelles occurred via receptor-mediated endocytosis using folate receptors. The pH-induced destabilization of PHSM/f led to rapid distribution of drug and polymer throughout the cells, most likely due to polyHis-mediated endosomal disruption. This reduced the likelihood of drug efflux via exocytosis from resistant tumor cells.

Key words

exocytosis folate multidrug resistance pH-sensitive polymeric micelle poly(l-histidine) 



The authors would like to thank Deepa Mishra (University of Utah) for carefully editing the English in this manuscript. This work was supported by NIH CA101850.


  1. 1.
    D. Boesch, C. Gaveriaux, B. Jachez, A. Pourtier-Manzanedo, P. Bollinger, and F. Loor. In vivo circumvention of P-glycoprotein-mediated multidrug resistance of tumor cells with SDZ PSC 833. Cancer Res. 51:4226–4233 (1991).PubMedGoogle Scholar
  2. 2.
    M. Sehested, T. Skovsgarrd, B. van Deurs, and H. Winther-Nielsen. Increase in nonspecific adsorptive endocytosis in anthracycline- and vinca alkaloid-resistant Ehrlich ascites tumor cell lines. J. Natl. Cancer Inst. 78:171–179 (1987).PubMedGoogle Scholar
  3. 3.
    S. M. Simon and M. Schindler. Cell biological mechanisms of multidrug resistance in tumors. Proc. Natl. Acad. Sci. 91:3497–3504 (1994).PubMedCrossRefGoogle Scholar
  4. 4.
    A. M. Cataldo, S. Petanceska, C. M. Peterhoff, N. B. Terio, C. J. Epstein, A. Villar, E. J. Carlson, M. Staufenbiel, and R. A. Nixon. App gene dosage modulates endosomal abnormalities of Alzheimer’s disease in a segmental trisomy 16 mouse model of down syndrome. J. Neurosci. 23:6788–6792 (2003).PubMedGoogle Scholar
  5. 5.
    D. A. Lazzarino, P. Blier, and I. Mellman. The monomeric guanosine triphosphatase rab4 controls an essential step on the pathway of receptor-mediated antigen processing in B cells. J. Exp. Med. 188:1769–1774 (1998).PubMedCrossRefGoogle Scholar
  6. 6.
    J. van Adelsberg and Q. Al-Awqati. Regulation of cell pH by Ca2+-mediated exocytotic insertion of H-ATPase. J. Cell Biol. 102:1638–1645 (1998).CrossRefGoogle Scholar
  7. 7.
    A. Hager, G. Debus, H. G. Edel, H. Stransky, and R. Serrano. Auxin induces exocytosis and the rapid synthesis of a high-turnover pool of plasma-membrane H+ ATPase. Planta 185:527–537 (1991).CrossRefGoogle Scholar
  8. 8.
    L. Warren, J. C. Jardillier, and P. Ordentlich. Secretion of lysosomal enzymes by drug-sensitive and multiple drug-resistant cells. Cancer Res. 51:1996–2001 (1991).PubMedGoogle Scholar
  9. 9.
    J. H. Hooijberg, G. J. Peters, Y. G. Assaraf, I. Kathmann, D. G. Priest, M. A. Bunni, A. J. Veerman, G. L. Scheffer, G. J. Kaspers, and G. Jansen. The role of multidrug resistance proteins MRP1, MRP2 and MRP3 in cellular folate homeostasis. Biochem. Pharmacol. 65:765–771 (2003).PubMedCrossRefGoogle Scholar
  10. 10.
    M. M. Gottesman, and I. Pastan. Biochemistry of multidrug resistance mediated by the multidrug transporter. Annu. Rev. Biochem. 62:385–427 (1993).PubMedCrossRefGoogle Scholar
  11. 11.
    S. Naito, A. Yokomizo, and H. Koga. Mechanisms of drug resistance in chemotherapy for urogenital carcinoma. Int. J. Urol. 6:427–439 (1999).PubMedCrossRefGoogle Scholar
  12. 12.
    E. Aronica, J. A. Gorter, G. H. Jansen, C. W. van Veelen, P. C. van Rijen, S. Leenstra, M. Ramkema, G. L. Scheffer, R. J. Scheper, and D. Troost. Expression and cellular distribution of multidrug transporter proteins in two major causes of medically intractable epilepsy: focal cortical dysplasia and glioneuronal tumors. Neuroscience. 118:417–429 (2003).PubMedCrossRefGoogle Scholar
  13. 13.
    Y. G. Assaraf, L. Rothem, J. H. Hooijberg, M. Stark, I. Ifergan, I. Kathmann, B. A. C. Dijkmans, G. J. Peters, and G. Jansen. Loss of multidrug resistance protein 1 expression and folate efflux activity results in a highly concentrative folate transport in human leukemia cells. J. Biol. Chem. 278:6680–6686 (2003).PubMedCrossRefGoogle Scholar
  14. 14.
    Z. S. Chen, K. Lee, S. Walther, R. B. Raftogianis, M. Kuwano, H. Zeng, and G. D. Kruh. Analysis of methotrexate and folate transport by multidrug resistance protein 4 (ABCC4): MRP4 is a Component of the Methotrexate Efflux System. Cancer Res. 62:3144–3150 (2002).PubMedGoogle Scholar
  15. 15.
    A. Reymann, A. Bunge, S. Laer, and M. Dietel. Morphological and functional features of cytostatic drug resistance and the effects of MDR modulators. Pharmazie 51:171–176 (1996).PubMedGoogle Scholar
  16. 16.
    E. J. Demant, M. Sehested, and P. B. Jensen. A model for computer simulation of P-glycoprotein and transmembrane delta pH-mediated anthracycline transport in multidrug-resistant tumor cells. Biochim. Biophys. Acta 1055:117–125 (1990).PubMedCrossRefGoogle Scholar
  17. 17.
    J. Panyam and V. Labhasetwar. Dynmaics of endocytosis and exocytosis of poly(D,L-lactide-co-glycolide) nanoparticles in vascular smooth muscle cells. Pharm. Res. 20:212–220 (2003).PubMedCrossRefGoogle Scholar
  18. 18.
    J. S. Park, T. H. Han, K. Y. Lee, S. S. Han, J. J. Hwang, D. H. Moon, S. Y. Kim, and Y. W. Cho. N-acetyl histidine-conjugated glycol chitosan self-assembled nanoparticles for intracytoplasmic delivery of drugs: Endocytosis, exocytosis and drug release. J. Control. Release 115:37–45 (2006).PubMedCrossRefGoogle Scholar
  19. 19.
    S. K. Sahoo and V. Labhasetwar. Enhanced antiproliferatively activity of transferring-conjugated paclitaxel-loaded nanoparticle is mediated via sustained intracellular drug retention. Mol. Pharmacol. 2:373–383 (2005).CrossRefGoogle Scholar
  20. 20.
    J. A. Reddy and P. S. Low. Folate-mediated targeting of therapeutic and imaging agents to cancers. Crit. Rev. Ther. Drug Carr. Syst. 15:587–627 (1998).Google Scholar
  21. 21.
    R. J. Lee and P. S. Low. Folate-mediated tumor cell targeting of liposome-entrapped doxorubicin in vitro. Biochem. Biophys. Acta 1233:134–144 (1995).PubMedCrossRefGoogle Scholar
  22. 22.
    M. Stark, L. Rothem, G. Jansen, G. L. Scheffer, I. D. Goldman, and Y. G. Assaraf. Antifolate resistance associated with loss of MRP1 expression and function in Chinese Hamster ovary cells with markedly impaired export of folate and cholate. Mol. Pharmacol. 64:220–227 (2003).PubMedCrossRefGoogle Scholar
  23. 23.
    P. Midoux and M. Monsigny. Efficient gene transfer by histidylated polylysine/pDNA complexes. Bioconjug. Chem. 10:406–411 (1999).PubMedCrossRefGoogle Scholar
  24. 24.
    A. Kichler, C. Leborgne, J. Marz, O. Danos, and B. Bechinger. Histidine-rich amphipathic peptide antibiotics promote efficient delivery of DNA into mammalian cells. Proc. Natl. Acad. Sci. U S A 100:1564–1568 (2003).PubMedCrossRefGoogle Scholar
  25. 25.
    K. W. Mok and P. R. Cullis. Structural and fusogenic properties of cationic liposomes in the presence of plasmid DNA. Biophys. J. 73:2534–2545 (1997).PubMedCrossRefGoogle Scholar
  26. 26.
    E. S. Lee, K. Na, and Y. H. Bae. Doxorubicin loaded pH-sensitive polymeric micelles for reversal of resistant MCF-7 tumor. J. Control. Release 103:405–418 (2005).PubMedCrossRefGoogle Scholar
  27. 27.
    E. S. Lee, K. Na, and Y. H. Bae. Polymeric micelle for tumor pH and folate-mediated targeting. J. Control. Release 91:103–113 (2003).PubMedCrossRefGoogle Scholar
  28. 28.
    E. S. Lee, K. Na, and Y. H. Bae. Super pH-sensitive multifunctional polymeric micelle. Nano Lett. 5:325-329 (2005).PubMedCrossRefGoogle Scholar
  29. 29.
    E. S. Lee, H. J. Shin, K. Na, and Y. H. Bae. Poly(L-histidine)-PEG block copolymer micelles and pH-induced destabilization. J. Control. Release 90:363–374 (2003).PubMedCrossRefGoogle Scholar
  30. 30.
    N. Oku, N. Yamaguchi, N. Yamaguchi, S. Shibamoto, F. Ito, and M. Nango. The fusogenic effect of synthetic polycations on negatively charged lipid bilayers. J. Biochem. (Tokyo) 100:935–944 (1986).Google Scholar
  31. 31.
    G. M. Kim, Y. H. Bae, and W. H. Jo. pH-induced micelle formation of poly(hisitidine-co-phenylalanine)-block-poly(ethylene glycol) in aqueous media. Macromol. Biosci. 5:1118–1124 (2005).PubMedCrossRefGoogle Scholar
  32. 32.
    Z. G. Gao, D. H. Lee, D. I. Kim, and Y. H. Bae. Doxorubicin loaded pH-sensitive micelle targeting acidic extracellular pH of human ovarian A2780 tumor in mice. J. Drug Target. 13:391–397 (2005).PubMedCrossRefGoogle Scholar
  33. 33.
    L. D. Skarsgard, D. K. Acheson, A. Vinczan, B. C. Wouters, B. E. Heinrichs, D. W. Loblaw, A. I. Minchinton, and D. J. Chaplin. Cytotoxic effect of RB 6145 in human tumour cell lines: dependence on hypoxia, extra- and intracellular pH and drug accumulation. Br. J. Cancer. 72:1479–1486 (1995).PubMedGoogle Scholar
  34. 34.
    J. M. Benns, J. S. Choi, R. I. Mahato, J. S. Park, and S. W. Kim. pH-sensitive cationic polymer gene delivery vehicle: N-Ac-poly(L-histidine)-graft-poly(L-lysine) comb shaped polymer. Bioconjug. Chem. 11:637–645 (2000).PubMedCrossRefGoogle Scholar
  35. 35.
    D. Putnam, C. A. Gentry, D. W. Pack, and R. Langer. Polymer-based gene delivery with low cytotoxicity by a unique balance of side-chain termini. Proc. Natl. Acad. Sci. 98:1200–1205 (2001).PubMedCrossRefGoogle Scholar
  36. 36.
    C. Y. Wang and L. Huang. Polyhistidine mediates an acid-dependent fusion of negatively charged liposomes. Biochemistry 23:4409–4416 (1984).PubMedCrossRefGoogle Scholar
  37. 37.
    E. Mastrobattista, D. J. Crommelin, J. Wilschut, and G. Storm. Targeted liposomes for delivery of protein-based drugs into the cytoplasm of tumor cells. J. Liposome Res. 12:57–65 (2002).PubMedCrossRefGoogle Scholar
  38. 38.
    H. Schwarzenbach. Expression of MDR1/P-glycoprotein, the multidrug resistance protein MRP, and the lung-resistance protein LRP in multiple myeloma. Med. Oncol. 19:87–104 (2002).PubMedCrossRefGoogle Scholar
  39. 39.
    T. Nakanishi, S. Fukushima, K. Okamoto, M. Suzuki, Y. Matsumura, M. Yokoyama, T. Okano, Y. Sakurai, and K. Kataoka. Development of the polymer micelle carrier system for doxorubicin. J. Control. Release 74:295–302 (2001).PubMedCrossRefGoogle Scholar
  40. 40.
    K. Kataoka, T. Matsumoto, M. Yokoyama, T. Okano, Y. Sakurai, S. Fukushima, K. Okamoto, and G. S. Kwon. Doxorubicin-loaded poly(ethylene glycol)-poly(beta-benzyl-L-aspartate) copolymer micelles: their pharmaceutical characteristics and biological significance. J. Control. Release 64:143–153 (2000).PubMedCrossRefGoogle Scholar
  41. 41.
    A. Reddy and P. S. Low. Enhanced folate receptor mediated gene therapy using a novel pH-sensitive lipid formulation. J. Control. Release 64:27–37 (2000).PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.Department of Pharmaceutics and Pharmaceutical ChemistryUniversity of UtahSalt Lake CityUSA

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