Mifepristone Therapy in Ovarian Cancer

1
Mifepristone Therapy in Ovarian Cancer

• Carlos Telleria, Ph.D.

INBRE Investigator University of South Dakota
2
Epithelial ovarian cancer

• The most fatal cancer of the female reproductive
  tract
• If diagnosed and treated while cancer is limited
  to the ovaries, the 5-year survival rate is
  90-95
• Only 19 of all ovarian cancers are diagnosed at
  early stages

3
2005 predictions in the US

• American Cancer Society
• New Cases 22,220 Death 16,210
• Yearly mortality is approx. 72 of the incidence
  rate
• Lack of early diagnose

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Mifepristone
RU486

• Commonly known as RU486 or abortion pill
• First synthesized in 1980s and described as a
  progesterone receptor antagonist

Progesterone
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Mifepristone

• Termination of pregnancy
• Approved in the US on 2000
• Only when pregnancy confirmed
• Associated with a prostaglandin analog
• Emergency contraception
• Within 72 h of unprotected intercourse
• Not approved in the US for this purpose

6
Mifepristone other potential uses

• Endometriosis
• Uterine fibroids
• Meningioma
• Interference with cancer cell growth
• Breast cancer
• Endometrial cancer
• Gastric adenocarcinoma
• Ovarian cancer

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Overall goal

• To characterize the molecular mechanism of cell
  growth arrest induced by Mifepristone in ovarian
  cancer cells

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Mifepristone inhibits SK-OV-3 cell growth
displaying progesterone-like effect
A
B
C
LNG
MPA
PROG
6
6
6
5
5
5
4
4
4
Number of Viable Cells (x 105)
3
3
3
Number of Viable Cells (x 105)
Number of Viable Cells (x 105)
2
2
2
1
1
1
0
0
0
Concentration (mM)
Concentration (mM)
Concentration (mM)
D
F
E
MF
6
100
5
75
4
Number of Viable Cells (x 105)
3
50
Inhibition of Cell Growth
2
25
1
0
0
MF
Concentration (mM)
LNG
MPA
PROG
9
Mifepristone is cytostatic but not cytotoxic to
SK-OV-3 cells
SK-OV-3 cells
- Sap
10
Mifepristone induces loss of clonogenic survival
in SK-OV-3 cells in a dose- and time-dependent
manner
11
Mifepristone inhibits DNA synthesis
VEH
MF
12
Effect of Mifepristone on cell cycle traverse in
SK-OV-3 cells
13
Cell cycle arrest of SK-OV-3 cells induced by
Mifepristone associates with decreased abundance
of Cdk2 and up-regulation of p21CIP1 and p27KIP1
14
Cell cycle arrest of SK-OV-3 cells induced by
Mifepristone associates with deregulation of the
pRb/E2F pathway
Mifepristone (h)
Co
24
48
72
ppRb
Under Rb
E2F
GAPDH
15
Mifepristone-induced deregulation ofthe pRb/E2F
pathway associates with down-regulation of genes
whose expression is dependent on S-phase
progression
Mifepristone (h)
Co
24
48
72
Cyclin A
Cyclin B1
CDK1
GAPDH
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The cytostatic effect of Mifepristone is mediated
by reduced Cdk2 activity
SK-OV-3 cells
17
Schematic model for a cytostatic mechanism of
Mifepristone in ovarian cancer cells
18
Therapeutic potential of Mifepristone in ovarian
cancer
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Acknowledgements

• Collaborators

Alicia Goyeneche
Elizabeth Freeburg
Stacy Rowenhorst

• Funding

2 P20 RR016479 from the INBRE Program, NIH, NCRR
South Dakota Health Research Foundation
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Conclusions I

• Mifepristone has progesterone-like effects
  inhibiting growth of SK-OV-3 ovarian cancer
  cells.
• Mifepristone-induced inhibition of SK-OV-3 cell
  growth is not accompanied by short-time death but
  induces loss of clonogenic survival.

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Conclusions II

• Mifepristone-induced inhibition of SK-OV-3 cell
  growth is associated with arrest in G1 phase of
  the cell cycle.
• Mifepristone-induced G1 arrest in SK-OV-3 cells
  involves up-regulation of cyclin-dependent kinase
  inhibitors p21cip1 and p27kip1, down-regulation
  of Cdk2 and transcription factor E2F, and
  decreased activity of Cdk2.

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Mifepristone is cytostatic but not cytotoxic to
SK-OV-3 cells
SK-OV-3 cells
- Sap
24
The cytostatic effect of Mifepristone is mediated
by reduced Cdk2 activity
25
The cytostatic effect of Mifepristone is mediated
by reduced Cdk2 activity
2008
SK-OV-3
p21CIP1
p21CIP1
p27KIP1
p27KIP1
Cdk2
Cdk2
GAPDH
GAPDH
Co
24
48
72
12
48
72
Co
24
MF (h)
MF (h)
Cdk2 Activity
Cdk2 activity
P- Histone H1
P- Histone H1
Co
24
48
72
Co
12
48
24
72
MF (h)
MF (h)
26
Mifepristone-induced deregulation ofthe pRb/E2F
pathway associates with down-regulation of genes
whose expression is dependent on S-phase
progression
Mifepristone (h)
Co
24
48
72
Cyclin A
Cyclin B1
CDK1
GAPDH
27
Does Mifepristone interferes cell cycle
progression?
Doubling of DNA
Point of no return