Resistance to Cytotoxic Drugs and Drug/Hormone Interactions



We have been studying the mechanisms of resistance to the systemic cytotoxic drug and endocrine therapies, and potential interactions between these therapies, for a number of years. Previously, we demonstrated the ability of some cytotoxic drugs to affect both expression of the estrogen receptor and response to tamoxifen. Our focus has been on exploring the role of the P-glycoprotein product of the human mdr1 gene. P-glycoprotein can act as an efflux pump, which results in low intracellular concentrations of drugs within cells. It has a broad substrate specificity, affecting many of the most active drugs used in the management of breast cancer, e.g., Taxanes (paclitaxel, docetaxel), Vinca alkaloids (vinblastine, vincristine), anthracylines (adriamycin).

Several years ago we have published the results of the first meta analysis to explore the possible expression of P-glycoprotein and its mRNA in breast cancers (Trock et al. J Natl cancer Inst, 1997). These results showed P-glycoprotein/mdr1 expression to be widely detected in breast cancer, associated with prior cytotoxic chemotherapy, and with a worse than partial response to chemotherapy in patients. In studies into the interactions between cytotoxic drugs, endocrine agents and response/resistance, we have shown that the antiestrogen tamoxifen interacts synergistically with cytotoxic P-glycoprotein substrates in cells expressing mdr1. However, tamoxifen is not a classical P-glycoprotein substrate, since cells overexpressing mdr1 retain responsiveness to tamoxifen.

We have designed, synthesized, and evaluated a series of novel C7-progesterone analogs as P-glycoprotein reversing agents. These compounds have a high affinity for P-glycoprotein, but neither activate nor inhibit the transcriptional regulatory functions of either the progesterone or glucocorticoid receptors, and are predicted to have low inherent toxicity.

Despite having been cloned over 30 years ago, the precise role of mdr1 in conferring multiple drug resistance in breast cancer remains controversial. There are many reasons for this including inconsistencies in the methods used to measure expression, differences in the patient populations studied and the drugs used, the presence of polymorphisms in the gene, and the frequent lack of requiring Pgp expression in studies of possible reversing agents. More recent studies using Technetium (ppmTC) sestamibi to functionally image Pgp appear to have greater potential to address the role of this protein in drug resistance (Leonessa et al. Semin Oncol, 2005).

Some of our more recent work has focused on generating new models of resistance to Taxanes and on the role of caveolin-1 in affecting responsiveness to these drugs (Shajahan et al. J Biol Chem, 2007). We have recently commented on the challenge of responding in this field. (Hatzis et al. Cancer Research, 2014).

Selected Publications

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Year 10s

  1. Hatzis C, Bedard PL, Birkbak NJ, Beck AH, Aerts HJ, Stern DF, Shi L, Clarke R, Quackenbush J, Haibe-Kains B. Enhancing Reproducibility in Cancer Drug Screening: How Do We Move Forward? Cancer Res. 2014 Aug 1;74(15):4016-4023. Epub 2014 Jul 11. PubMed
  2. Riggins, R.B., Mazzotta, M.M., Maniya, O.Z. & Clarke, R. “Orphan nuclear receptors in breast cancer pathogenesis and therapeutic response.” Endocr-Relat Cancer, 17: R213-221, 2010.

Year 00s

  1. Clarke, R. “The role of preclinical animal models in breast cancer drug development.” Breast Cancer Research, 11(Suppl 3): S22, 2009.
  2. Shajahan, A.N., Riggins, R.B. & Clarke, R. “The role of X-box binding protein-1 in tumorigenicity” Drug News Perspect, 22: 241-246, 2009.
  3. Chen, L. Xuan, J., Riggins, R.B., Wang, Y. Hoffman, E.P., Riggins, R.B., & Clarke, R. "Identification of condition-specific regulatory modules through multi-level motif and mRNA expression analysis," Int J Comp Biology Drug Design, 2: 1-20, 2009.
  4. Deb, T.B., Ramlijak, D., Dickson, R.B., Johnson, M.D. & Clarke, R. “Signaling pathways in the normal and neoplastic breast.” In: “Handbook of Cell Signaling.” Eds: Thompson, B.E.; Elsevier, Inc. New York, NY; in press.
  5. Shajahan, A.N., Riggins, R.B. & Clarke, R. “Apoptosis, cell death and breast cancer” Chapter 8. In: “Breast cancer: prognosis, treatment, and prevention.” Eds: Pasqualini, J.R., Informa Healthcare; New York, NY; pp137-156, 2008.
  6. Shajahan, A., Wang, A., Decker, M., Minshall, R.D., Liu, M.C. & Clarke, R. “Caveolin-1 tyrosine phosphorylation (Y14) enhances paclitaxel-mediated cytotoxicity.” J Biol Chem, 282: 5934-5943, 2007. PubMed
  7. Clarke, R., Leonessa, F. & Trock, B. “MDR/P-glycoprotein and breast cancer: Review and meta-analysis.” Semin Oncol, 32 (suppl 7): 9-15, 2005.
  8. Zhu, Y., Wang, A., Liu, M.C., Zwart, A., Lee, R.Y., Gallagher, A., Wang, Y., Miller, W.R., Dixon, J.M. & Clarke, R. “Estrogen Receptor alpha (ER) positive breast tumors and breast cancer cell lines share similarities in their transcriptome data structures.” Int Oncol, in press.
  9. Riggins, R.B., Zwart, A., Nehra, R. & Clarke, R. “The nuclear factor kappa B inhibitor parthenolide restores ICI 182,780 (Faslodex; fulvestrant)-induced apoptosis in antiestrogen-resistant breast cancer cells.” Mol Cancer Ther. 2005 Jan;4(1):33-41.
  10. Leonessa, F. & Clarke, R. ATP binding cassette transporters and drug resistance in breast cancer. Endocr Relat Cancer, 10: 43-73, 2003.
  11. Leonessa, F., Kim, J.-H., Ghiorghis, A., Kulawiec, R. Hammer, C., Talebian, A. & Clarke R. “C-7 analogs of progesterone as potent inhibitors of the P-glycoprotein efflux pump.” J Med Chem,45: 390-398, 2002.
  12. Welch, J.N. & Clarke, R. “ErbB-2 expression and drug resistance in cancer.” Signal, 3: 4-9, 2002.
  13. Lu, L., Leonessa, F., Clarke, R. & Wainer, I.W. “Competitive and allosteric interactions in ligand binding to P-glycoprotein as observed on an immobilized P-glycoprotein liquid chromatographic stationary phase.” Mol Pharmacol, 59:62-68, 2001.
  14. Lu, L., Leonessa, F., Baynham, M.T., Clarke, R., Gimenez, F., Pham, Y.-T., Roux, F. & Wainer, I.W. “The enantioselective binding of mefloquine enantiomers to P-glycoprotein determined using an immobilized P-glycoprotein liquid chromatographic stationary phase.” Pharmaceut Res, 18: 1327-1330, 2001.
  15. Zhang, Y., Leonessa, F., Clarke, R. & Wainer, I.W. “Development of an immobilization of P-glycoprotein stationary phase for on-line liquid chromatographic determination of drug-binding affinities.” J Chromatogr B, 739: 33-37, 2000.

Year 90s

  1. Plouzek, C.A., Morris, D.W., Clarke, R. & Yeh, G.C. “Rosemary: a new P-glycoprotein reversal agent of chemotherapeutic drugs in drug-resistant human breast cancer cells.” Eur J Cancer, 35:1541-1545, 1999.
  2. Trock, B., Leonessa, F. & Clarke, R. “Multidrug resistance in breast cancer: a meta-analysis of MDR1/gp170 expression and its possible functional significance.” J Natl Cancer Inst, 89: 917-931, 1997.
  3. Leonessa, F., Green, D., Licht, T., Wright, A., Wingate-Legette, K., Lippman, J., Gottesman, M.M. & Clarke, R. “MDA435/LCC6 and MDA435/LCC6MDR1: ascites models of human breast cancer.” Br J Cancer,73:154-161, 1996.
  4. Leonessa, F., Jacobson, M., Boyle, B., Lippman, J., McGarvey, M. & Clarke, R. “The effect of tamoxifen on the multidrug resistant phenotype in human breast cancer cells: isobologram, drug accumulation, and gp-170 binding studies.” Cancer Res, 54: 441-447, 1994.
  5. Zyad, A., Bernard, J., Clarke, R., Tursz, T., Brockhaus, M. & Chouaib, S. “Human breast cancer cross-resistance to TNF and adriamycin: relationship to MDR1, MnSOD and TNF gene expression.” Cancer Res, 54: 825-831, 1994.
  6. Clarke R., Currier, S., Kaplan, O., Boulay, V., Gottesman, M. & Dickson, R.B. “Effect of P-glycoprotein expression on sensitivity to hormones in MCF-7 human breast cancer cells.” J Natl Cancer Inst,84: 1506-1512, 1992.
  7. Clarke, R., Lippman, M.E. & Dickson, R.B. “Hormonal aspects of breast cancer: growth factors, drugs and stromal interactions.” Crit Rev Oncol Hematol, 12: 1-23, 1992.
  8. Kaplan, O., Jaroszewski, J.W., Clarke, R., Fairchild, C.R., Schoenlein, P., Goldenberg, S., Gottesman, M.M. & Cohen, J. “The multi-drug resistance phenotype: 31P NMR characterization and 2-deoxyglucose toxicity.” Cancer Res,51: 1638-1644, 1991.
  9. Clarke, R., Lippman, M.E. & Dickson, R.B. “Mechanism of hormone and cytotoxic drug interactions in the development and treatment of breast cancer.” Prog Clin Biol Res, 322: 243-278, 1990.

Year 80s

  1. Clarke, R. & van den Berg, H.W. “Adverse interactions between cytotoxic drugs and hormonal agents in human breast cancer cells.” J Clin Oncol, 7: 1580-1582, 1989.
  2. Clarke, R., van den Berg, H.W. & Murphy, R.F. “The ability of oestrogen to modulate the effects of cytotoxic drugs in human breast cancer cells; influence of oestrogen receptor (ER) status and choice of drug.” Biochem Soc Trans, 15: 242-243, 1987.
  3. Clarke, R., Morwood, J., van den Berg, H.W., Nelson, J. & Murphy, R.F. “The effect of cytotoxic drugs on estrogen receptor expression and response to Tamoxifen in MCF-7 cells.” Cancer Res, 46: 6116-6119, 1986.
  4. Kennedy, D.G., van den Berg, H.W., Clarke, R. & Murphy, R.F. “Enhancement of the sensitivity of MDA-MB-436 human breast cancer cell line to methotrexate by dipyridamole.” Biochem Pharmacol, 35: 3053-3056, 1986.
  5. Clarke, R., van den Berg, H.W., Kennedy, D.G. & Murphy, R.F. “Oestrogen receptor status and the response of human breast cancer cells to a combination of methotrexate and 17b-oestradiol.” Br J Cancer, 51: 365-369, 1985.
  6. Kennedy, D.G., van den Berg, H.W., Clarke, R. & Murphy, R.F. “The effect of leucovorin on the synthesis of methotrexate poly-g-glutamates in the MCF-7 human breast cancer cell line.” Biochem Pharmacol, 34: 2897-2903, 1985.
  7. Kennedy, D.G., Clarke, R., van den Berg, H.W. & Murphy, R.F. “The kinetics of methotrexate polyglutamate formation and efflux in a human breast cancer cell line (MDA-MB-436): the effect of insulin.” Biochem Pharmacol, 32: 41-46, 1983.
  8. Clarke, R., van den Berg, H.W., Kennedy, D.G. & Murphy, R.F. “Reduction of the antimetabolic and antiproliferative effects of methotrexate by 17b-oestradiol in a human breast carcinoma cell line (MDA-MB-436).” Eur J Cancer Clin Oncol, 19: 19-24, 1983.
  9. van den Berg, H.W., Clarke, R. & Murphy, R.F. “Failure of 5-fluorouracil and methotrexate to destroy the reproductive integrity of a human breast cancer cell line (MCF-7) growing in vitro.” Eur J Cancer Clin Oncol, 17: 1275-1281, 1981.
Other manuscripts submitted and in preparation