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Nuclear Imaging of Multidrug Resistance (MDR)

Nuclear Imaging of Multidrug Resistance (MDR). Hee-Seung Bom cnuh.com. Mechanisms of MDR. 1. P-glycoprotein (Pgp) 2. MDR-associated protein (MRP) 3. DNA topoisomerase II 4. Tripeptide GSH 5. Lung resistant related protein (LRP). P-glycoprotein. ATP-dependent 170-180 kDa

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Nuclear Imaging of Multidrug Resistance (MDR)

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  1. Nuclear Imaging of Multidrug Resistance (MDR) Hee-Seung Bom cnuh.com

  2. Mechanisms of MDR 1. P-glycoprotein (Pgp) 2. MDR-associated protein (MRP) 3. DNA topoisomerase II 4. Tripeptide GSH 5. Lung resistant related protein (LRP)

  3. P-glycoprotein ATP-dependent 170-180 kDa encoded by the MDR1 gene located on chromosome 7 (7q21.1) Substrates: anthracyclines (doxorubicin, daunorubicin) vinca alkaloids (vincristine) epipodophyllotoxins (etoposide) taxanes (paclitaxel) Modulators: calcium channel blockers cyclosporin A, PSC 833

  4. Hypothetical model for P-glycoprotein "vacuum cleaner" "flippase" model "aqueous pore"-transporter Muller: J Hepatol, Volume 28(2).February 1998.344-354

  5. Molecular Mechanisms for the ABC-ATPase Superfamily Members Hopfner K.P., Karcher A., Shin D.S., Craig L., Arthur L.M., Carney J.P. and Tainer J.A. Structural biology of Rad50-ATPase: ATP-driven conformational control in DNA double-strand break repair and the ABC-ATPase superfamily. Cell, (2000) 101:789-800.

  6. Normal distribution of Pgp adrenal cortex intestinal mucosal cells biliary hepatocytes renal proximal tubule epithelium pancreatic ductules pregnant uterus gastrointestinal epithelium blood capillaries of the brain and testes CD34+ bone marrow stem cells Function? protection by extruding toxins out of organs protect critical organs such as brain and testes

  7. GF120918 (inhibitor of Pgp) Choroid plexus epithelial expression of MDR1 P-glycoprotein and MRP contribute to the blood-cerebrospinal-fluid drug-permeability barrier Proc Natl Acad Sci, USA 1999; 96:3900-5

  8. Pgp is especially expressed in Renal cell ca hepatoma pheochromocytoma colon ca Many Pgp modulators in trials; ineffectivity >> side effects

  9. Techniques to measure MDR1 gene or MRP expression DNA PCR Southern blotting mRNA RT-PCR Northern blotting protein immunohistochemistry Western blotting MDR1 mRNA =/= Pgp efflux pump

  10. DNR accumulation PCR 100% 50 F: fresh medium O: old medium 0 F O F O Expression Function Prolongation of medium exchange is associated with a decrease in function but not expression of the P-glycoprotein pump in leukaemic cells. European Journal of Haematology. 1996; 56:12-22

  11. expression function myeloblastic cell line mature high low immature low high Lack of correlation between expression and function of P-glycotprotein in acute myeloid cell lines. Leukemia 1995; 9:799-807

  12. Functional Imaging of Pgp SPECT Tc-99m sestamibi Tc-99m tetrofosmin Tc-99m Q complex (Tc-99m Q12: furifosmin) PET [C-11] daunorubicin [C-11] colchicine [C-11] verapamil [Ga-68] gallium(III) complexes [Co-64] bis(diphosphine) complexes

  13. Tc-99m sestamibi vs. Tc-99m tetrofosmin Verapamil index similar Wolf et al. EJNM 1996; 23:1095 sestamibi Nakamura et al. EJNM 1996; 23:1142 MRP reversal similar Utsunomiya et al. EJNM 2000;27:1786 MIBI, TF vs. furifosmin MDR(-) soft tissue sarcoma cell lines EJNM 2000; 27:1839

  14. MDR(-) cell line MDR(+) cell line JNM 2001; 42:646-54 Lessons from investigations using nuclear imaging on MDR 1. Tc-99m complexes (MIBI, TF, FF; Tc-C) are substrates of Pgp. Tl-201 is not. 2. Accumulation (esp. of MIBI) in resistant tumors is lower than in sensitive tumors.

  15. 3. Pgp expression is inversely proportional to accumulation of Tc-C in tumor cells. 4. Intensity of Tc-C efflux out of tumor cells is good measure of MDR. accumulation efflux JNM 2001; 42:1476-83

  16. 20 10 5. MDR modulators increase accumulation of Tc-C. (e.g. PSC 833, GW 0918, KR 30035) % Uptake of Tc-99m MIBI Basal Cyclosporin 10 uM 0 KJNM 1999; 33:152-62 L1210 Adr Cell Vcr Cell

  17. Lesson from clinical studies using Tc-99m MIBI 1. Increased efflux rate from tumors with elevated Pgp expression, Increased uptake correlates with angiogenesis. 2. Rapid clearance out of tumor correlates with lack of response to chemotherapy. 3. Inverse correlation between T/N ratio and Pgp expression. Positive correlation between retention and chemosensitivity. Tc-99m MIBI uptake (T/N 1h) 5.0 p=0.006 4.0 3.0 2.0 1.0 CR PR NR JNM 1998; 39:91-4 0 Response to chemotherapy in SCLC

  18. 10min 180min 10min 180min Tc-99m MIBI Scintimammography Clin Nucl Med. 1999 ; 24:314-8.

  19. 4.0 Tc -99m Sestamibi uptake at 10 min (T/N10) 3.0 2.0 r = 0.47 p= 0.008 n = 31 1.0 0 10 20 30 40 50 60 70 Angiogenesis (CD34) Clin Nucl Med. 1999 ; 24:314-8.

  20. Washout Index (%) = (TN10-TN180)/TN10 X 100 40 30 20 10 0 O I II III IV -10 Pgp expression Clin Nucl Med. 1999 ; 24:314-8.

  21. 4. In malignant lymphoma, MIBI uptake correlates with the response to chemotherapy. 5. SCLC: Pgp expression correlates with T/N ratio but not with washout. (debate) 6. Bone and soft tissue tumor: Pgp expression correlates with washout but not with uptake. 7. AML, ALL: Inverse correlation between BM/B ratio and Pgp expression. 10 min 180 min

  22. F-18 FDG PET MDR(-) tumor MDR(+) tumor JNM 2001; 42:646-54 • GLUT-1 levels are diminished progressively with elevated Pgp levels. • Cancer Lett. 1997;115:221-7

  23. Multidrug resistance-associated protein (MRP) 190 kDa MRP1; encoded by MRP1 gene located on chromosome 16 (16p13.1) ATP-binding cassette (ABC) superfamily present in almost all cells of the human body cytoplasm: endoplasmic reticulum or Golgi apparatus

  24. MRP: Mechanism of action Glutathione S-conjugate efflux pump (GS-X pump) GSH dependent MRP1 ~ MRP5 Substrates of MRP: Leukotriens (LT) LTC4, LTD4, LTE4Modulator: BSO (buthionine sulfoximine) PET: N-[C-11]acetyl-LTE4 SPECT: Tc-99m sestamibi Tc-99m tetrofosmin

  25. Lessons from investigations using nuclear imaging on MRP 1. Tc-C is substrate of MRP1 as well as Pgp. 2. Lowering cellular glutathione increase Tc-C uptake in MRP1- positive cells, not in Pgp-positive cells. Tc-99m TF uptake Basal 1.58 GSH depletion by BSO 3.16 buthionine sulfoximine Biochem Phramacol 2000; 60:413-26 MRP(-) MRP(+)

  26. Basolateral transport systems HEPATOCYTE Canalicular transport systems Trauner: J Hepatol, Volume 31(1).July 1999.165-178

  27. Mutations in MRP2 in patients with Dubin-Johnson syndrome THOMPSON: Semin Liver Dis, Volume 20(3).August 2000.365-372

  28. DNA topoisomerase II enzyme Target for many drugs: anthracyclines, epipodophyllotoxins Decreased topoisomerase II = less DNA damage

  29. Tripeptide GSH faciliate drug metabolism to less active compounds detoxification of drug-induced free radicals

  30. Lung resistant related protein (LRP) 110 kDa Major vault protein Nucleo-cytoplasmic transport

  31. Pgp vs. MRP vs. LRP Tc-99m MIBI accumulation Tc-99m MIBI washout JNM 2001; 42:1476-83

  32. Problems • Various mechanisms for MDR • Pgp, MRP, topoisomerase II, LRP, etc. • No specific markers for each genes or proteins • Inefficient modulators with side effects

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