Metal-Based Drugs: Novel Targets

Antiulcer

Bulk elements Trace elements Possibly essential

H

Li

Na

K

Rb

Cs

Fr

Be

Mg

Ca

Sr

Ba

Ra

Sc

Y

Ln

Ac

Ti

Zr

Hf

Th

V

Nb

Ta

Pa

Cr

Mo

W

U

Mn

Tc

Re

Ru

Os

Fe Co

Rh

Ir

Ni

Pd

Pt

Cu

Ag

Au

Zn

Cd

Hg

B C N O F

Al Si P S Cl

Ga

In

Tl

Ge

Sn

Pb

As

Sb

Bi

Se

Te

Po

Br

I

At

He

Ne

Ar

Kr

Xe

Rn

Metallopharmaceuticals

Anti-Depressive

Insulin Mimetic

Diagnostic Agents: X-ray, MRI

Radiopharmaceuticals

Anticancer

Antiarthritic

Antiinfective

Metal-Based Drugs: New targets

Current ARC funded projects

Kinetics and mechanism of binding of platinum

anticancer drugs to DNA

Development of metal-based antimitochondrial

antitumour agents

University of Western Australia Prof Sue Berners-PriceDr Junyong (June) ZhangDon ThomasJoe Moniodis

Virginia Commonwealth University, USA Prof Nick Farrell (Network International Advisory panel USA)

FundingARC Discovery (2002-4), ARC Linkage Int (2002-4)NIH, NSF, Am Cancer Soc.

FacilitiesUWA NMR Facility (600, 500 MHz Spectrometers)

DNA Interactions of platinum anticancer drugs

NH2(CH2)n

2+

NH2(CH2)nH2N NH3 Cl

Cisplatin

M50ID (L1210) = 2.4 TWI%(LX-1) = 38@4.0 mg/kg

1,1/t,t; n=6 (BBR3005)

50 ID (L1210) = 3.03 MTWI%(LX-1) = 72@3.0 mg/kg

1,0,1/t,t,t; (n = 6,6) (BBR3464)

ID50 (L1210) = 0.0094 MTWI%(LX-1) = 73@0.3 mg/kg

Cl

PtH3N

H3N Cl

Pt

H3N

Cl NH3 ClPt

H3N

H2N NH3

Pt

H3N

Cl NH3 NH2(CH2)nPt

H3N NH3Pt

H2N

H3N

4+

02468101214

imino

1H NMR : 14-mer DNA duplex

T-CH3

Pt-NH3

Pt-NH2

+ 1.6 mM

(4 h 25 oC)

Pt

NH2(CH2)6H3N

Cl NH3 NH2(CH2)6Pt

H3N

H2N NH3

NH3Pt

H2N

H3N Cl

4+

aromatic(G H8)

/ppm

15N-

5.4 5.2 5.0 4.8

-44

-46

-48

1H

15N

[1H, 15N] NMR : 14-mer DNA duplex

+ 1.6 mM 15N- (4 h 25 oC)Pt

NH2(CH2)6H3N

Cl NH3 NH2(CH2)6Pt

H3N

H2N NH3

NH3Pt

H2N

H3N Cl

4+

Pt-NH2

-60

-62

-64

4.6 4.4 4.2 4.0

Pt-NH3

EndGroups

Linker

EndGroups

Linker

(H2O)

4.6

1,4- and 1,6-GG Interstrand Crosslink Formation

Pt

PtCl

Cl

GT

AC G

TA

CTA

AT

GT

AC G

TA

CTA

AT

Pt

PtCl

GT

AC G

TA

CTA

AT

Pt

PtOH2

Pt

Pt

Cl

OH2

+

G

C GT

AC

TA

AT

APt

PtT

kH kk

k

k

-H

2

1

3

Cox et al J. Am. Chem. Soc. 123, 1316-1326 (2001)Hegmans et al. J. Am. Chem. Soc. (2004) in press.

[Pt2](mM)

0 10 20 30 40 50Time (h)

0.00

0.50

1.50

2.00

1.00

0 10 20 30 40 50Time (h)

0.00

0.40

0.80

1.20

1.60

2.00

Kinetics of formation of 1,6- and 1,4- Interstrand Crosslinks

5'-d(A-T-A-T-G-T-A-C-A-T-A-T)3'-d(T-A-T-A-C-A-T-G-T-A-T-A)

(1,4-GG)

5'-d(T-A-T-G-T-A-T-A-C-A-T-A)3'-d(A-T-A-C-A-T-A-T-G-T-A-T)

(1,6-GG)

G/G G/GCl/Cl Cl/Cl

G/Cl G/Cl

Y/Y

PtH3N NH2

NH3H2NPtNH3

NH2H3N

Y 4+

PtH2N NH3

H3N Y

Formation of a 1,4- GG Interstrand Crosslink

Guanine N7

Metal-Based Drugs: New targets

Current ARC funded projects

Kinetics and mechanism of binding of platinum anticancer drugs

to DNA

Development of metal-based antimitochondrial antitumour

agents

[Au(dppe)2]Cl: Antitumour Activity

Active against a spectrum of mouse tumour models (4 i.p. tumours; 3 s.c. tumours)

Active in a cisplatin-resistant subline of P388 leukaemia

Acts synergistically with cisplatin against moderately advanced P388 leukaemia

Berners-Price at. al. (1986) Cancer Research 46, 5486

M = Au(I), Ag(I), Cu(I)

P

Ar

Ar

PAr

+

M

P

Ar

ArAr

Ar

Ar

PP P

R

R

R

R

1

2

3

4

R1-R4

N

2-pyridylN

3-pyridyl

N

4-pyridyl

or or

Metal complexes of bidentate pyridyl phosphines

Cytotoxic potency against human ovarian tumours vs partition coefficient

X SKOV-3 CH 1/ -cisR/ 41 M/ -cisR/

P P

+

P PR´

R´

R

R

R´

R´

R

R

M

Partition coefficient

IC50

(M)[Au(dppe)2]+

0.0

0.1

1

10

100

1000

0.01 0.1 1 10 100

0 5 10 15 20 0 5 10 15 20 0 5 10 15 20

Antitumour activity vs log kw

Colon 38 mouse tumour model

Time (days)

100

10

1

100

10

1

100

10

1

RelativeTumourVolume

R = 2-pyridylR = 4-pyridyl

log Kw

5.4log Kw

2.2log Kw

2.9

[Au(dppe)2]Cl (R = Ph)

McKeage et al. Cancer Chemother. Pharmacol. 2000, 46, 343

Apoptosis

released frommitochondria byapoptotic stimuli

accumulatewithinmitochondria

inhibits apoptosis, bindsICE proteins and

suppresses release of cytochrome c and AIF

Mitochondrial Control of Apoptosis

Antitumour

LipophilicCations

cytochrome c

AIF

Bcl2

CED-4

ICE

?

+

-

+

-

Mitochondria

Cytoplasm

Mitochondrial Permeability Transition Pore Complex

å

Bax,Bak

Bcl-2

Cyclophilin-D

Adenine Nucleotide Translocase

Benzodiazepin receptorHexokinase

Voltage Dependent Anion Channel

Creatine KinaseIntermembrane

space

Matrix

å

Bax,Bak

Bcl-2

Inhibitor:Cyclosporin A

Inducers: Ca2+, ROS, NOthiol oxidation

Inhibitor: thiol reduction

Inducers: PBR ligands Inducers:BH3 peptides

Inducers: Ca2+, ROS

Intermembranespace

Matrix

Mitochondrial Permeability Transition Pore Complex

Targeting mitochondrial cell death pathways in chemotherapy

More than 20 cytotoxic drugs are now known to induce cell death by

permeabilizing mitochondrial membranes

(demonstrated in a cell-free system)

e.g.

_ Etoposide, Paclitaxel,

_ PBR ligands (PK11195)

_ ANT ligands : Ionidamine, Arsenite, CD437

See Debatin, Poncet, Kroemer, Oncogene, 2002 21 8786-8803

Antimitochondrial activity of Auranofin

At submicromolar concentrations

Auranofin induces mitochondrial

permeability transition (requires Ca2+,

cyclosporin-A sensitive)

Attributed to inhibition of mitochondrial

thioredoxin reductase

Au(I) binds to active site selenocysteine

O

H

AcO

H

AcO

H

H

OAcHS

OAc

Au PEt3

Rigobello, Bindoli et al. Br. J. Pharmacol. (2002) 136 1162

Antimitochondrial activity

0 5 10 150

1

2

3

4

5IIII

II

IV

0 5 100.5

1.0

1.5

I

IIIII

IV

N

N

N

NN

N

N

N

Au

Au

2

N

N N

N N

NN

NAu

Au

2+

N

N

N

N

NN

N

NN

NAu

Au

2+

N

N

N N N N

NNNN

Au Au

2+

I II

IVIII

Abs

orba

nce

Time (min)

g A

u/m

g pr

otei

n

University of Western Australia Prof Sue Berners-Price Prof David DayA/Prof Murray Baker A/Prof George YeohDr Peter BarnardJames Hickey

FundingARC Discovery (Berners-Price, Baker 2004-6)Gold Phosphine and Carbene Complexes as Potential Antimitochondrial Agents: Design,Synthesis and BiologicalChemistry

CollaboratorsA/Prof Mark McKeage, Bruce Baguley (Auckland)Prof Peter Sadler (Edinburgh)(Network International Advisory panel (EU))