Development of Drug Resistance and Strategies to Circumvent it: A Brief Look Jin-Ming Yang, MD, PhD The Cancer Institute of New Jersey Department of Pharmacology UMDNJ-Robert Wood Johnson Medical School April 5, 2006
Simultaneous Resistance to Multiple Drugs in Cancer Intrinsic (primary, de novo) - before chemotherapy Acquired - after chemotherapy
Drug Resistance: The Major Obstacle to Successful Cancer Chemotherapy chemotherapy chemotherapy
Overview of Drug Resistance Mechanisms Increased efflux Decreased uptake Altered intracellular drug trafficking Altered drug metabolism (increased inactivation or decreased activation of drug ) Altered drug targets (qualitatively or quantitatively: Topo I and Topo II) Altered cellular metabolism Increased repair of drug-induced damage (membrane, protein or DNA) Altered gene expression (DNA amplification, mutation, deletion; transcription, translation) Altered signaling pathway
ABC Transporters Contributing to Cancer Drug Resistance P-gp/MDR1/ABCB1: classic MDR Doxorubicin, vinblastine, vincristine, paclitaxel, etc. MRP1/ABCC1 Doxorubicin, etoposide, methotrexate, vincristine, flutamide, etc. MRP2/CMOAT/ABCC2 Cisplatin, CPT-11, doxorubicin, etoposide, etc. MRP3/ABCC3 Methotrexate, etoposide, teniposide BCRP/ABCG2/MXR1 Camptothecin, CPT-11, mitoxantrone, epirubicin, etc.
P-glycoprotein (P-gp) 170-190 kda transmembrane glycoprotein (product of MDR1) Member of ATP binding cassette (ABC) superfamily Two transmembrane domains, two ATP binding domains Transports structurally and functionally diverse compounds - vinblastine, vincristine, doxorubicin, paclitaxel, colchicine, etoposide (VP-16), etc
Multidrug Resistance Phenotype 1. Exposure of cancer cells to a single anticancer drug results in the development of resistance to structurally and functionally diverse chemotherapeutic agents. 2. Associated with decreased drug accumulation due to active drug efflux. 3. Associated with expression of the MDR1 gene product, P-glycoprotein. 4. Overexpression of MDR1 occurs clinically in certain human tissues and tumors. 5. MDR can be reversed by chemosensitizers (modulators).
Effect of Multidrug Resistance on Chemotherapeutic Agents RESISTANT Vinblastine Vincristine Doxorubicin Daunomycin Actinomycin D Mitoxantrone Etoposide (VP-16) Teniposide (VM-26) SENSITIVE Cyclophosphamide Carmustine (BCNU) Melphalan Cisplatin Methotrexate Thioguanine Bleomycin Ara-C Paclitaxel (Taxol) Colchicine Mithramycin
Multidrug Resistance Phenotype 1. Exposure of cancer cells to a single anticancer drug results in the development of resistance to structurally and functionally diverse chemotherapeutic agents. 2. Associated with decreased drug accumulation due to active drug efflux. 3. Associated with expression of the MDR1 gene product, P-glycoprotein. 4. Overexpression of MDR1 occurs clinically in certain human tissues and tumors. 5. MDR can be reversed by chemosensitizers (modulators).
Current Problems: Many MDR modulators work perfectly in cell culture models, but do not work or have limited success in animal models and in clinical studies Possible Causes: 1) Pharmacokinetic alterations (chemotherapeutic agents and/or modulators)? 2) Inhibition of P-gp function in vivo? 3) Other mechanisms or patho-physiologic alteration associated with MDR? 4) Inability of modulators to reach effective concentrations at tumor sites? 5) Toxicity 6) More?
Survival Curves
MDR Drugs Increase Pulmonary Metastases P-gp (-) B16-BL6/S No. of metastases. Mean ± SE (n=5) Median (range) P-gp (+) B16-BL6/ADR0.25 No. of metastases. Mean ± SE (n=5) Median (range) Vehicle 30 ± 10 20 (10 60) 1.4 ± 0.8 b 0 (0 4) Vincristine 1.2 ± 0.6 a 1 (0 3) 8.0 ± 2.8 a 10 (0 15) Paclitaxel 1.0 ± 0.6 a 0.5 (0 3) 10 ± 3.2 a 10 (0 20) transflupenthixol 1.5 ± 0.8 a 1 (0 4) 13 ± 3.8 a 15 (0 22) Methotrexate 2.5 ± 0.8 a 2 (1 5) 0.25 ± 0.22 a 0 (0 1)
MDR Drugs Increase Membrane Ruffling and PI-3 Kinase Activity in the MDR1 Transfectant MCF-7/BC-19 Cells
Activity of MMP-9, MMP-2 and MMP-1 in Sensitive and MDR Cancer Cells
EMMPRIN/CD 147(basigin) Extracellular matrix metalloproteinase inducer Member of the immunoglobulin superfamily Glycoprotein, enriched on the surface of tumor cells Stimulates production of several MMPs (MMP-1, MMP-2, MMP-3, etc.)
EMMPRIN/CD147 is Overexpressed in MDR Cancer Cells
Knockdown of EMMPRIN by RNAi Induces Anoikis in Cancer Cells
Induction of MDR phenotype might be accompanied by other cellular, biochemical or molecular changes
To Combat MDR: Understand the changes or alterations associated with drug resistance Understand the detailed mechanism(s) of Drug resistance 1) How drug resistance is induced? 2) What signaling pathway(s) are involved? Develop novel strategies, approaches, drugs
Effect of sirna on Sensitivity of MDR Cancer Cells to Vinblastine, Doxorubicin and Hydroxyurea. Wu et al.: Cancer Res 2003
Effect of sirna on Accumulation of Doxorubicin in MDR Cancer Cells Wu et al.: Cancer Res 2003
Effect of sirna on Accumulation of Paclitaxel in MDR Cancer Cells Wu et al.: Cancer Res 2003
Approaches to Circumvent Cancer Drug Resistance Effective single (higher dose) or multiple drug therapy Rational drug design Drugs that inhibit efflux Drugs that enter cells effectively Drugs that target signaling pathways
Acknowledgments Dr. William N. Hait Dr. Zede Xu Dr. Ramsey Foty Dr. Hao Wu Andrew Vassil Dr. Daniel Medina Peter O Neill