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Downregulation of Ca2+-activated Cl-
channel TMEM16A by histone deacetylase
inhibition in breast cancer cells
Susumu Ohya, Ph.D.
Department of Pharmacology
Kyoto Pharmaceutical University
Kyoto, Japan
World Congress on
Breast Cancer 2015
Breast Cancer-2015, Birmingham, UK
August 4, 2015
Overview
1. Role of Ca2+-activated Cl- channel in cancer cells and
epigenetic modification of gene expression
2. Downregulation of Ca2+-activated Cl- channel, TMEM16A by
a histone deacetylase (HDAC) inhibitor, vorinostat in human
breast cancer cells
3. Effects of pharmacological and siRNA-based blockade of
HDAC on TMEM16A transcription
4. Regulation of HER2 expression by TMEM16A
Overview
1. Role of Ca2+-activated Cl- channel in cancer cells and
epigenetic modification of gene expression
2. Downregulation of Ca2+-activated Cl- channel, TMEM16A by
a histone deacetylase (HDAC) inhibitor, vorinostat in human
breast cancer cells
3. Effects of pharmacological and siRNA-based blockade of
HDAC on TMEM16A transcription
4. Regulation of HER2 expression by TMEM16A
Feske et al., Ann. Rev. Immunol., 33, 291-353 (2015)
Principal interplay between the Na+-, K+-, Ca2+- and Cl--
permeable channels
Gene regulation
DNA fragmentation
proliferation
migration
invasion
apoptosis
Ion channels and cancer
1. Ion channels contribute to various cancer
processes by the regulation of the resting
membrane potential and Ca2+ signaling.
2. Pharmacological inhibition of ion channels is
an attractive target to prevent cancer cell
proliferation and metastasis.
TMEM16A (ANO1) overexpression enhances cancer
cell proliferation through signaling pathways
Overexpression of TMEM16A (ANO1)
breast tumor Britschgi et al., Proc. Natl. Acad. Sci. U.S.A. (2013)
breast cancer cell lines Leanza et al., Front. Physiol. (2013)
Qu et al., Cancer Med. 3, 453-461 (2014)
Picollo et al., J. Mol. Biol. 427, 94-105 (2015)
chromosome 11q13
migration
TMEM16A is an attractive therapeutic target and a novel biomarker for cancer.
Epigenetic modification of gene expression
Histone
Deacetylase
Inhibitor
X Cancer
Cell
Death
histone acetylation
histone methylation
Epigenetic modification therapy with
HDAC inhibitors is one of the novel strategies for cancer treatment.
Overview
1. Role of Ca2+-activated Cl- channel in cancer cells and
epigenetic modification of gene expression
2. Downregulation of Ca2+-activated Cl- channel, TMEM16A by
a histone deacetylase (HDAC) inhibitor, vorinostat in human
breast cancer cells
3. Effects of pharmacological and siRNA-based blockade of
HDAC on TMEM16A transcription
4. Regulation of HER2 expression by TMEM16A
Vorinostat is approved for the treatment of T cell lymphoma and is
developed for the other solid tumors with combination drug therapy.
vorinostat pan-HDAC inhibitor
IC50=100-1000 nM for HDAC1-11
0.0
0.5
1.0
rela
tive c
ell v
iab
ilit
y
(3) (3)
**
0.00
0.05
0.10
0.15
rati
o t
o A
CT
B
YM
B-1
MD
A-M
B
-453
MC
F-7
MD
A-M
B
-231
MD
A-M
B
-468
n=3
BT
54
9
Hs
57
8T
A. TMEM16A mRNA
ER
PR
HER2
-
-
+
-
-
+
+
+/-
-
-
-
-
-
-
-
-
-
-
-
-
-
Functional expression of TMEM16A in YMB-1 cells
B. TMEM16A activity
in YMB-1
-50 mV -80 mV
500 ms
1000 pA
C. Cell viability
Matsuba et al., J. Pharmacol. Exp. Ther., 351, 510-518 (2014)
0.0
0.5
1.0
rela
tiv
e c
ell
via
bilit
y
A. Cell viability
**
**
(5) (5) (5) (5)
1 10
vorinostat
(µM)
0.1
B. TMEM16A mRNA
0.00
0.05
0.10
0.15
rela
tiv
e m
RN
A e
xp
res
sio
n
(ra
tio
to
AC
TB
)
1 10
vorinostat
(µM)
**
#
** (4) (4) (4)
Downregulation of TMEM16A by treatment with
vorinostat in YMB-1 cells (1)
0.0
0.4
0.8
1.2
rela
tive p
rote
in e
xp
ress
ion
**
C. TMEM16A protein
10 μm
vehicle
vorinostat (10 µM)
vorinostat pan-HDAC inhibitor
IC50=100-1000 nM for HDAC1-11
Matsuba et al., J. Pharmacol. Exp. Ther., 351, 510-518 (2014)
-50 mV -80 mV
500 ms
1000 pA
-60 -40 -20 0 20 40 600
1000
2000
3000
4000
voltage (mV)
cu
rren
t (p
A)
■ vehicle (8)
● vorinostat (7)
pCa6.0
**
Downregulation of TMEM16A by treatment with
vorinostat in YMB-1 cells (2)
A. vehicle
B. vorinostat (10 µM)
C. I-V relationship
500 ms
1000 pA
Matsuba et al., J. Pharmacol. Exp. Ther., 351, 510-518 (2014)
Overview
1. Role of Ca2+-activated Cl- channel in cancer cells and
epigenetic modification of gene expression
2. Downregulation of Ca2+-activated Cl- channel, TMEM16A by
a histone deacetylase (HDAC) inhibitor, vorinostat in human
breast cancer cells
3. Effects of pharmacological and siRNA-based blockade of
HDAC on TMEM16A transcription
4. Regulation of HER2 expression by TMEM16A Of 11 HDAC subtypes, HDAC1, 2, 3 and 6 are highly expressed in
YMB-1 cells in consistent with the expression patterns in human
tumor breast tissues.
0.0
0.4
0.8
1.2
rela
tiv
e p
rote
in e
xp
res
sio
n
0.00
0.05
0.10
0.15
rela
tive m
RN
A e
xp
ress
ion
(rati
o t
o A
CT
B)
*
**
A. TMEM16A mRNA AATB
T247
NCT-14b
HDAC1&HDAC2 inhibitor
IC50= 7 nM for HDAC1
IC50= 49 nM for HDAC2
HDAC6 inhibitor
IC50= 82 nM for HDAC6
HDAC3 inhibitor
IC50= 240 nM for HDAC3
Downregulation of TMEM16A by HDAC2/3 inhibition
in YMB-1 cells (1)
Matsuba et al., J. Pharmacol. Exp. Ther., 351, 510-518 (2014)
*
**
B. TMEM16A protein
n=4 n=4
-50 mV -80 mV
-60 -40 -20 0 20 40 600
1000
2000
3000
4000
voltage (mV)
cu
rren
t (p
A)
■ vehicle (7)
● T247 (4)
pCa6.0
** 500 ms
1000 pA
Downregulation of TMEM16A by HDAC2/3 inhibition
in YMB-1 cells (2)
0.00
0.04
0.08
0.12
rela
tive m
RN
A e
xp
ressio
n
(rati
o t
o A
CT
B)
**
**
B. vehicle
C. T247 (1 µM)
D. I-V relationship
500 ms
1000 pA
A. TMEM16A mRNA
Matsuba et al., J. Pharmacol. Exp. Ther., 351, 510-518 (2014)
n=4
HDAC3 is the leading candidate for the
downregulaion of TMEM16A in YMB-1 cells.
Overview
1. Role of Ca2+-activated Cl- channel in cancer cells and
epigenetic modification of gene expression
2. Downregulation of Ca2+-activated Cl- channel, TMEM16A by
a histone deacetylase (HDAC) inhibitor, vorinostat in human
breast cancer cells
3. Effects of pharmacological and siRNA-based blockade of
HDAC on TMEM16A transcription
4. Regulation of HER2 expression by TMEM16A
Lipid rafts, ion channel complexes and EGFR signaling
1) In the plasma membrane, ion channels and receptors
can functionally communicate by forming clusters of
lipid microdomains.
2) EGF receptor forms functional complexes with Ca2+-
activated Cl- channel and store-operated Ca2+ channels
and contributes to the Ca2+ signal pathway with them.
Gueguinou et al., Biochim. Biophys. Acta., 2736 (2014)
Lipid rafts, ion channel complexes and EGFR signaling
HER signaling pathway and its related cell processes
Rimawi et al., Annu. Rev. Med., 66, 111-128 (2015)
HER2 is
1) an EGF receptor family with
tyrosine kinase activity.
2) overexpressed in about 30 %
of patients with breast cancer.
3) the mainstay of targeted
therapy for the treatment of
invasive breast cancers.
0.0
0.2
0.4
rela
tiv
e m
RN
A e
xp
res
sio
n
(ra
tio
to
AC
TB
)
0.0
0.2
0.4
rela
tiv
e m
RN
A e
xp
res
sio
n
(ra
tio
to
AC
TB
)(3) (3)
*
A. HER2 mRNA
(4) (4)
**
HER2
HER2
Downregulation of HER2 by TMEM16A inhibition
in YMB-1 cells
B. HER2 mRNA C. HER2 protein
D. HER2 protein
Conclusions
1. Ca2+-activated Cl- channel, TMEM16A is a potential
therapeutic target for breast cancer, and inhibition of
TMEM16A suppresses proliferation and invasion.
2. In malignancies with a frequent gene amplification of
TMEM16A, TMEM16A dysfunction by HDAC3 inhibition
is at least in part responsible for the suppressive
effects on cell viability in breast cancer cells, and it
may be related to the poor invasion capacity observed
in metastatic breast cancer cells.
3. TMEM16A may play an important role in the regulation
of HER2-downstream signaling in breast cancer cells.
Acknowledgements
Kyoto Pharmaceutical University,
Kyoto,Japan
Masanori Fujii, Ph.D.
Hiroaki Kito, Ph.D.
Satomi Niwa, Ph.D.
Sayo Matsuba
Saki Kanatsuka
Yurika Nakazono
Aichi Gakuin University,
Nagoya, Japan
Electrophysiology
Katsuhiko Muraki, Ph.D.
Noriyuki Hatano, Ph.D.
Kyoto Prefectural University of Medicine,
Kyoto Japan
Chemical synthesis of HDAC inhibitors
Takayoshi Suzuki, Ph.D.
Peng Zhan, Ph.D.
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