Nuclear Imaging

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Nuclear Imaging of Multidrug Resistance (MDR)
Hee-Seung Bom cnuh.com
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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)
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P-glycoprotein
ATP-dependent 170-180 kDa encoded by the MDR1
gene located on chromosome 7 (7q21.1) Substrate
s anthracyclines (doxorubicin,
daunorubicin) vinca alkaloids (vincristine) epip
odophyllotoxins (etoposide) taxanes
(paclitaxel) Modulators calcium channel
blockers cyclosporin A, PSC 833
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Hypothetical model for P-glycoprotein
"vacuum cleaner"
"flippase" model
"aqueous pore"-transporter
Muller J Hepatol, Volume 28(2).February
1998.344-354
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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) 101789-800.
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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
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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 963900-5
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Pgp is especially expressed in
Renal cell ca hepatoma pheochromocytoma colon ca
Many Pgp modulators in trials ineffectivity gtgt
side effects
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Techniques to measure MDR1 gene or MRP expression
DNA PCR Southern blotting mRNA RT-PCR North
ern blotting protein immunohistochemistry West
ern blotting
MDR1 mRNA / Pgp efflux pump
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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 5612-22
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expression function myeloblastic cell
line mature high low immature low high Lac
k of correlation between expression and function
of P-glycotprotein in acute myeloid cell lines.
Leukemia 1995 9799-807
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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
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Tc-99m sestamibi vs. Tc-99m tetrofosmin
Verapamil index similar Wolf et al.
EJNM 1996 231095 sestamibi Nakamura et al.
EJNM 1996 231142 MRP reversal similar Utsunom
iya et al. EJNM 2000271786
MIBI, TF vs. furifosmin MDR(-) soft tissue
sarcoma cell lines EJNM 2000 271839
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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.
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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 421476-83
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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 33152-62
L1210
Adr Cell
Vcr Cell
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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
p0.006
4.0
3.0
2.0
1.0
CR
PR
NR
0
JNM 1998 3991-4
Response to chemotherapy in SCLC
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Tc-99m MIBI Scintimammography
Clin Nucl Med. 1999 24314-8.
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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 24314-8.
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Washout Index () (TN10-TN180)/TN10 X 100
40
30
20
10
0
O
I
II
III
IV
-10
Pgp
expression
Clin Nucl Med. 1999 24314-8.
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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
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F-18 FDG PET
MDR(-) tumor
MDR() tumor
JNM 2001 42646-54

• GLUT-1 levels are diminished progressively with
  elevated Pgp levels.
• Cancer Lett. 1997115221-7

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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
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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-11acetyl-LTE4 SPECT Tc-99m
sestamibi Tc-99m tetrofosmin
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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 60413-26
MRP(-)
MRP()
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Basolateral transport systems
HEPATOCYTE
Canalicular transport systems
Trauner J Hepatol, Volume 31(1).July 1999.165-178
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Mutations in MRP2 in patients with Dubin-Johnson
syndrome
THOMPSON Semin Liver Dis, Volume 20(3).August
2000.365-372
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DNA topoisomerase II enzyme
Target for many drugs anthracyclines,
epipodophyllotoxins Decreased topoisomerase II
less DNA damage
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Tripeptide GSH
faciliate drug metabolism to less active
compounds detoxification of drug-induced free
radicals
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Lung resistant related protein (LRP)
110 kDa Major vault protein Nucleo-cytoplasmic
transport
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Pgp vs. MRP vs. LRP
Tc-99m MIBI accumulation
Tc-99m MIBI washout
JNM 2001 421476-83
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Problems

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