The American Journal of Pathology, Vol. 178, No. 4, April 2011
Copyright © 2011 American Society for Investigative Pathology.
Published by Elsevier Inc. All rights reserved.
DOI: 10.1016/j.ajpath.2011.01.009
Short Communication
Somatic Mutations of PPP2R1A in Ovarian and
Uterine Carcinomas
Ie-Ming Shih,*† Pradeep K. Panuganti,†
Kuan-Tin Kuo,§ Tsui-Lien Mao,§ Elisabetta Kuhn,†
Sian Jones,‡ Victor E. Velculescu,‡
Robert J. Kurman,*† and Tian-Li Wang*
From the Departments of Gynecology and Obstetrics * and
Pathology † and Johns Hopkins Kimmel Cancer Center,‡ Johns
Hopkins Medical Institutions, Baltimore, Maryland; and the
Department of Pathology,§ National Taiwan University College of
Medicine, Taipei, Taiwan
Exome sequencing of ovarian clear-cell carcinoma
has identified somatic mutations in PPP2R1A, a
subunit of protein phosphatase 2A. The present
study was performed to determine the frequency
of PPP2R1A mutations in exon 5, which harbors
previously reported mutation hot spots, and adjacent exon 6, in 209 ovarian and 56 uterine tumors
of various histologic subtypes. PPP2R1A mutations
were demonstrated in 10 of 110 type I ovarian tumors (9.1%) including low-grade serous, low-grade
endometrioid, clear-cell, and mucinous carcinomas. In contrast, none of 71 type II ovarian (highgrade serous) carcinomas exhibited PPP2R1A
mutations. Moreover, PPP2R1A mutations were observed in 2 of 30 type I uterine (endometrioid) carcinomas (6.7%) and 5 of 26 type II uterine (serous)
carcinomas (19.2%). Of the 18 mutations, 13 affected the R182 or 183, and there were 5 novel
mutations including 3 involving S256, 1 involving
W257, and 1 involving P179. All mutations were
located in the ␣-helix repeats near the interface
between the A subunit and the regulatory B subunit
of the enzyme complex. These data provide new
evidence that PPP2R1A somatic mutations occur in
certain types of uterine and ovarian neoplastic lesions, especially uterine serous carcinomas, and
suggest that mutation of PPP2R1A may participate
in the pathogenesis of ovarian type I and uterine
type II carcinomas. (Am J Pathol 2011, 178:1442–1447;
DOI: 10.1016/j.ajpath.2011.01.009)
1442
A recent genome-wide sequencing analysis of all exons from ovarian clear cell carcinomas led to the discovery of somatic missense mutations in PPP2R1A in
approximately 7% of these tumors.1 PPP2R1A encodes
a constant regulatory subunit of the protein phosphatase 2A holoenzyme, which is one of four major serinethreonine phosphatases.2 Protein phosphatase 2A is
composed primarily of a catalytic C subunit and a
scaffolding subunit A (PPP2R1A and PPP2R1B) and a
regulatory subunit B. Protein phosphatase 2A can be
regulated by binding of at least 18 different regulatory
B subunits to the core enzyme. The regulatory B subunit has been implicated in controlling the substrate
specificity, cellular localization and enzymatic activity
of protein phosphatase 2A, which participates in negative regulation of cellular proliferation among several
other cellular functions.2,3 Moreover, the regulatory
subunit competes with virus-producing proteins including the small T antigens of the papovaviruses SV40
and polyoma, and the middle T antigen of polyoma,4
which suggests that protein phosphatase 2A has a role
in the pathogenesis of virus-associated tumors.
Uterine carcinomas can be classified as type I or type
II, and develop along unique molecular pathways. Type I
uterine tumors are composed of endometrioid carcinomas, which frequently harbor mutations in CTNNB1,
PTEN, ARID1A (BAF250A), and PIK3CA, whereas type II
tumors are composed of serous carcinomas, which contain TP53 mutations in most cases.5 Patients with type I
tumors are typically younger, and carcinoma develops at
an earlier stage and has a more indolent clinical course
than in patients with type II tumors. Type I uterine carcinomas arise from endometrial hyperplasia, whereas type
Supported by grants RSG-08-174-01-GMC from the American Cancer
Society, and the Ovarian Cancer Research Fund (T.L.W.); the Dr. Miriam
and Sheldon G. Adelson Medical Research Foundation (V.V.); grants
NTUH-98N1265 and NSC-98-2320-B-002-040 (K.T.K.); and grants
CA103937 and CA129080 (I.M.S.), CA121113 (V.V.), and CA116184
(R.J.K.) from the National Institutes of Health.
Accepted for publication January 7, 2011.
Address reprint requests to Dr. Ie-Ming Shih, Department of Pathology,
The Johns Hopkins Hospital, 1550 Orleans St, CRB2, 305, Baltimore, MD
21231. E-mail: ishih@jhmi.edu.
PPP2R1A Mutations in Gynecologic Cancers
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AJP April 2011, Vol. 178, No. 4
II uterine carcinomas develop from endometrial intraepithelial carcinoma. Compared with uterine carcinoma,
ovarian carcinoma is far more complex and includes
more histologic subtypes than uterine tumors do.6 To
provide a conceptual framework for the study of the
pathogenesis of ovarian cancer, a dualistic model was
proposed that organizes the clinical, pathologic, and
molecular features of ovarian cancer by categorizing
them into type I and type II groups, similar to the
classification of uterine carcinoma.7 Type I tumors include low-grade serous, low-grade endometrioid,
clear-cell, and mucinous carcinomas, which develop in
a stepwise fashion from well-established precursor lesions such as borderline tumors and endometriosis.
Type I tumors typically are manifested as a large mass
confined to one ovary, and are associated with a relatively good prognosis. They typically exhibit mutations
in KRAS, PIK3CA, PTEN, and CTNNB1, and rarely in
TP53.6,8 In contrast, type II tumors include high-grade
serous carcinomas, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinomas. Type II tumors constitute most ovarian cancers
and account for most deaths. They are detected at an
advanced stage (stages II to IV) in greater than 75% of
cases, grow rapidly, and are highly aggressive. Type II
tumors, of which high-grade serous carcinoma is the
prototypic type, are chromosomally highly unstable,9,10 and harbor TP53 mutations in most cases but
rarely demonstrate mutations in KRAS, PIK3CA, PTEN,
and CTNNB1.11,12
The present study sought to extend the previous observation of somatic mutations of PPP2R1A in ovarian
clear-cell carcinomas1 by examining the mutational profiles of a variety of histologic types of ovarian and uterine
carcinomas that have been broadly classified as type I
and type II tumors.5,7 Sequence analysis was performed
in 256 ovarian and uterine tumors, focusing on exon 5,
which harbors the codons that encode amino acids 182
and 183, which, according to the previous study, represent mutational “hot spots” in PPP2R1A.1 Exon 6 was also
analyzed in all tumors.
Materials and Methods
Tissue Specimens
Tissue specimens from 265 ovarian and uterine tumors
were analyzed for mutations at exons 5 and 6 including
the codons 182 and 183 of PPP2R1A.1 Type I ovarian
tumors included 44 clear-cell carcinomas, 6 mucinous
tumors, 20 low-grade serous carcinomas, and 40 lowgrade endometrioid carcinomas. Type I uterine carcinoma included 30 low-grade (grade 1) endometrioid carcinomas. Type II ovarian tumors included 71 high-grade
serous carcinomas. Type II uterine carcinomas included
26 serous carcinomas, 3 of which contained clear-cell
carcinoma components. Those uterine carcinomas with
mixed serous and clear-cell histologic features were classified as serous carcinoma. The diagnosis of uterine serous carcinomas was supported at immunohistochemis-
try, which demonstrated diffuse p53 staining and a
high (⬎50%) Ki-67 labeling index. One hundred sixtyseven specimens were affinity-purified using BerEP4
antibody-conjugated magnetic beads (Invitrogen
Corp., Carlsbad, CA) following a previously described
protocol13. The remaining samples were obtained from
FFPE tissues after microdissection to enrich tumor
cells. The ovarian clear-cell carcinomas analyzed represented new cases that had not been studied in the previous report.1 In addition, 14 serous, 13 mucinous, and 1
seromucinous ovarian borderline tumors were analyzed.
Specimens were obtained from The Johns Hopkins
Hospital or the National Taiwan University Hospital.
H&E-stained sections were reviewed to confirm the
diagnosis before performing the experiments. All human tissue was collected anonymously using protocols
approved by the institutional review boards of both
hospitals.
DNA Extraction and Mutation Analysis
Genomic DNA was isolated using a DNeasy Blood and
Tissue Kit (Qiagen, Inc., Valencia, CA) for BerEP4 bead–
purified tumor cells, and a QIAamp DNA Micro Kit (Qiagen, Inc.) for paraffin-embedded tissues. To enrich tumor
cells from paraffin sections, pipette tips were used to
individually scrape off the normal tissues, followed by
tumor tissues, which were collected in separate microfuge tubes. For tumor tissues, only regions containing
at least 60% of tumor cells were dissected. The selection
of normal and tumor areas was made by two pathologists
(I.M.S. and E.K.). PCR amplification was performed using
the following primer pairs, which were designed to amplify the genomic DNA fragment of exon 5 flanking the
arginine couplet at codons 182 and183: forward primer
5=-TACTTCCGGAACCTGTGCTC-3= and reverse primer
5=-CCAGGAAGCAAAACTCACCT-3=. The PCR primers
used to amplify exon 6 were: forward primer 5=-GTTCCTGCCCATGAAAGAGA-3=, reverse primer 5=-TTATTGCTCAAACGCCCAAT-3=, and sequencing primer 5=-AATGGTTCCATCGGCCTAAT-3=.
PCR conditions were as follows: 94°C for 2 minutes;
three cycles at 94°C for 15 seconds, 64°C for 30 seconds, and 70°C for 30 seconds; three cycles at 94°C
for 15 seconds, 61°C for 30 seconds, and 70°C for 30
seconds; three cycles at 94°C for 15 seconds, 58°C for
30 seconds, and 70°C for 30 seconds; and 30 cycles at
94°C for 15 seconds, 57°C for 30 seconds, and 70°C
for 30 seconds, followed by 70°C for 5 minutes. Sanger
DNA sequencing was performed by Beckman Coulter
Genomics (Danvers, MA) using the sequencing primer
5=-CAAAACTCACCTGCTCGTCA-3=. Mutational analysis was performed using a software package (Mutation
Surveyor; SoftGenetics LLC, State College, PA). To
confirm somatic mutations, DNA from matched normal
tissue was sequenced using the same method. All of
the detected mutations were repeated at least twice to
confirm the results and rule out potential PCR errors.
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AJP April 2011, Vol. 178, No. 4
Table 1. Summary of PPP2R1A Mutation in Uterine and
Ovarian Tumors
Tumor
Tumor
type
No. of
cases
Cases with
mutation,
no. (%)
I
II
30
26
2 (6.7)
5 (19.2)
I
I
I
I
II
20
44
40
6
71
0 (0)
4 (9.1)
4 (10)
2 (33.3)
0
14
13
1
0
0
1 (100)
Uterine cancer
Endometrioid
Serous*
Ovarian cancer
Low-grade serous
Clear cell
Low-grade endometriod
Mucinous
High-grade serous
Ovarian borderline tumor
Serous
Mucinous
Seromucinous
*Three uterine carcinomas exhibited mixed features of clear-cell and
serous carcinoma.
Results
Of 265 tumor tissues analyzed, PPP2R1A mutations at
either exon 5 or 6 were detected in 18 tumors (Table 1).
Their associated normal tissues contained wild-type sequences, confirming that the PPP2R1A mutations were
somatic. The tumors with PPP2R1A mutations were of
various subtypes of ovarian or uterine tumors except
ovarian high-grade and low-grade serous carcinoma, in
which no somatic mutations were found. Specifically, in
ovarian carcinomas, PPP2R1A mutations were found in 4
of 44 ovarian clear-cell carcinomas (9.1%), 2 of 6 ovarian
mucinous carcinomas (33.3%), and 4 of 40 ovarian lowgrade endometrioid carcinomas (10%). In addition,
PPP2R1A mutation was also recorded in 1 of 28 ovarian
borderline tumors (3.6%). The mutation was observed in
the seromucinous borderline tumor at codon 183 but not
in the other borderline tumors. In uterine carcinomas,
mutations were detected in 5 of 26 serous carcinomas
(19.2%) (including those cases with mixed clear-cell and
serous carcinoma), of which mutation frequency was
greater than 6.7% in the uterine endometrioid carcinomas. Among the mutations, 1 uterine carcinoma demonstrated mixed clear-cell and serous components. Thus,
18 PPP2R1A mutations were identified. Of these, 13 mutations affected the R182 and R183 hot spots, which were
identified in a previous report,1 and there were 5 novel
mutations including 3 involving S256, 1 involving W257,
and 1 involving P179 (Table 2). All PPP2R1A mutations
identified were missense mutations and were heterozygous. Representative chromatograms of somatic alterations from an ovarian low-grade endometrioid carcinoma
(6026T) and a uterine serous carcinoma (319T) are
shown in Figure 1.
In addition, mutation profiles of PPP2R1A, KRAS, and
PIK3CA were determined. This analysis included cases
with PPP2R1A mutations that had been previously reported (three clear-cell carcinoma tissue samples, three
clear-cell carcinoma cell lines, and one pancreatic cancer tissue),1,14 to increase the number of cases. The
Table 2. Mutation Profiles of PPP2R1A, KRAS, and PIK3CA
Gene
Sample
Histologic subtype
PPP2R1A
TW-7
TW-11
TW-24
TW-28
OV81†
109T†
192TCS†
KK†
OVISE†
OVTOKO†
KT-41
KT-44
KT-36
TS
OS
EM-17T
EM-21T
314TCS
6026TCS
702TCS
319TCS
UPSC_5§
UCC_1T§
UCC_3T§
PA10X¶
Ovarian clear cell
Ovarian clear cell
Ovarian clear cell
Ovarian clear cell
Ovarian clear cell
Ovarian clear cell
Ovarian clear cell
Clear-cell carcinoma cell line
Clear-cell carcinoma cell line
Clear-cell carcinoma cell line
Mucinous
Mucinous
Ovarian endometrioid
Ovarian endometrioid
Ovarian endometrioid
Uterine endometrioid
Uterine endometrioid
Ovarian seromucinous borderline
Ovarian endometrioid
Uterine serous
Uterine serous
Uterine serous
Uterine serous/clear cell
Uterine serous
Pancreatic carcinoma
R183W (547 C⬎T)
R183W (547 C⬎T)
R183Q (548 G⬎A)
R183W (547 C⬎T)
R183W (547 C⬎T)
R182W (544 C⬎T)
R183G (547 C⬎G)
R183Q (548 G⬎A)
R183W (547 C⬎T)
R183G (547 C⬎G)
R183Q (548 G⬎A)
R183Q (548 G⬎A)
R183W (547 C⬎T)
R183W (547 C⬎T)
R182W (544 C⬎T)
R183W (547 C⬎T)
R182W (544 C⬎T)
R183W (547 C⬎T)
R183Q (548 G⬎A)
S256Y (767 C⬎A)
S256F (767 C⬎T)
P179R (536 C⬎G)
W257G (769 T⬎G)
S256F (767 C⬎T)
R183W (547 C⬎T)
†
PPP2R1A mutation identified in a previous report.1
Unless otherwise indicated, all mutations are heterozygous.
§
Genomic DNA isolated from paraffin-embedded tissues.
¶
PPP2R1A mutation identified in a previous report.14
‡
K-RAS
No mutation
No mutation
No mutation
No mutation
No mutation
No mutation
G12D (35 G⬎A)
No mutation
No mutation
No mutation
G12D (35 G⬎A homo)‡
G12D (35 G⬎A)
No mutation
No mutation
No mutation
No mutation
No mutation
G12D (35 G⬎A)
No mutation
No mutation
No mutation
NA
NA
NA
G12R (34 G⬎C)
PIK3CA
No mutation
No mutation
No mutation
No mutation
No mutation
E545K (1633 G⬎A)
No mutation
E545A (1634 A⬎C)
No mutation
No mutation
No mutation
No mutation
E545A (1634 A⬎C)
M1043T (3128T⬎C)
N1044K (3132T⬎A)
No mutation
H1047R (3140 A⬎G)
H1047R (3140 A⬎G)
No mutation
No mutation
H1047R (3140 A⬎G)
NA
NA
NA
No mutation
PPP2R1A Mutations in Gynecologic Cancers
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Figure 1. Examples of somatic mutations in PPP2R1A. Chromatogram of the sequences demonstrates a somatic mutation (548G⬎GA, 183R⬎RQ) in an ovarian
endometrioid carcinoma, 6026T, and a novel mutation (767C⬎TC, 256S⬎SF) in a uterine serous carcinoma, 319T. The matched normal tissues (6026N and 319N)
do not show the mutations. Both tumor tissues were affinity-purified. Arrows indicate the nucleotides with sequence mutation.
results for mutation status of KRAS, PIK3CA, and
PPP2R1A are given in Table 2. In contrast to the mutually
exclusive pattern of KRAS and BRAF mutations previously reported,15,16 a mutually exclusive mutation pattern
between PPP2R1A and KRAS or between PPP2R1A and
PIK3CA was not observed. Of 25 tumors with PPP2R1A
mutations, 5 tumors harbored concurrent KRAS mutations and 8 tumors harbored concurrent PIK3CA mutations (Table 2). Sequencing PIK3CA and KRAS in 54
ovarian and uterine carcinomas with wild-type PPP2R1A
demonstrated a mutation frequency in PIK3CA and KRAS
similar to that in tumors that had mutations in PPP2R1A.
Of those PPP2R1A wild-type cases, 19 (35%) demonstrated PIK3CA mutations and 5 (9%) demonstrated
KRAS mutations. There was no significant correlation of
PPP2R1A mutation status with either KRAS or PIK3CA
mutations (P ⬎ 0.2, Fisher exact test).
Discussion
The present study, by using an independent set of tumor
samples, not only verified that somatic PPP2R1A mutations occur in nearly 10% of ovarian clear-cell carcinomas1 but also demonstrated that PPP2R1A mutations
were detected in other types of ovarian and uterine carcinomas except ovarian serous carcinoma, the conventional type of ovarian cancer. Also identified were novel
somatic mutations located outside the previously reported hot-spot region of residues of R182 and R183. The
results of this study should have several implications in
understanding the molecular pathogenesis of both ovarian and uterine carcinomas. It also provides a biological
foundation for studying the roles of PPP2R1A mutations in
the development of uterine serous carcinoma.
The presence of PPP2R1A mutations in type I but not
type II ovarian carcinomas is of great interest and provides further molecular genetic evidence to support the
dualistic model of ovarian carcinogenesis. Although the
overall frequency of PPP2R1A mutations in ovarian clearcell, endometrioid, and mucinous carcinomas was only
9.1%, this observation suggests that PPP2R1A mutations
most likely contribute a functional effect in development
of some type I ovarian tumors, whereas type II ovarian
carcinomas such as high-grade serous carcinomas may
use PPP2R1A-indepent pathways for their development.
Furthermore, the data suggest that PPP2R1A mutations
may be related to those tumors arising either from
endometrium or endometriosis. This is because uterine
endometrioid and serous carcinomas develop from
endometrium and ovarian clear-cell and endometrioid carcinomas, and seromucinous borderline tumors
are closely associated with endometriosis.17–20 Thus,
PPP2R1A mutations were observed in15 of 140 tumors
(10.7%) related to endometrium or endometriosis, and
the frequency was significantly greater than 2.4% in
tumors not related to endometrium and endometriosis
(P ⫽ 0.0072, Fisher exact test). The present study
evaluated only gynecologic malignant lesions; however, other tumor types may also harbor PPP2R1A mutations. For example, a previous genome-wide sequencing analysis of pancreatic cancer identified a
point mutation at the R183 residue of PPP2R1A in 1 of
24 tumors.14 Further studies analyzing PPP2R1A mutations in other types of cancer in humans are necessary to determine whether such mutations are generally enriched in tumors related to endometrium and
endometriosis.
That PPP2R1A mutations occurred only in uterine serous carcinomas (uterine type II) but not in ovarian highgrade serous carcinomas (ovarian type II) suggests that
although both tumor types share several clinicopathologic features, the pathogenesis is different in uterine
serous carcinomas and ovarian high-grade serous carcinomas. The relatively high frequency of PPP2R1A mutations (19.2%) in uterine serous carcinoma warrants further investigation of its biological role in the development
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Shih et al
AJP April 2011, Vol. 178, No. 4
of this highly aggressive uterine carcinoma. In addition to
TP53 mutations, PPP2R1A mutation is the most common
sequence mutation in uterine serous carcinoma. All mutations in uterine serous carcinomas were located outside the R182 and R183, which raises the possibility
that distinct mechanisms may be involved in generating the mutations at different locations.
Because the protein phosphatase 2A is implicated in
regulation of signaling pathways including MAPK and
AKT,21,22 whether mutations of PPP2R1A coexisted with
KRAS or PIK3CA mutations was analyzed because genes
that regulate the MAPK and AKT pathways are frequently
mutated in ovarian and uterine type I tumors.5,6 From the
perspective of cancer genetics, the lack of a mutually
exclusive pattern between PPP2R1A and KRAS mutations or between PPP2R1A and PIK3CA mutations suggests that PPP2R1A mutations likely do not participate in
signaling pathways involving KRAS and PI3K. However,
future cell biology studies are needed to delineate
whether there is cross-talk between protein phosphatase
2A pathway and the MAPK or AKT pathway.
A previous study1 of ovarian clear cell carcinomas
demonstrated that all of the PPP2R1A mutations were
located in the pairs of arginine residues at R182 and
R183.1 However, analysis of the 18 PPP2R1A mutations
in the present study identified new mutation positions at
P179, S256, and W257. All mutations were located in the
codons that are evolutionary conserved, and structural
biology studies have demonstrated that the amino acids
P179, R182, and R183 are located in the ␣-helix repeat 5,
and amino acids S256 and W257 in the ␣-helix repeat 7.
Both repeats are near the interface between the A subunit
and the regulatory B subunit.23 Mutations in several residues in the interface of A and B subunits such as P179,
M180, and W257 have been reported to disrupt the interaction between these two subunits.24 Because the mutations observed in this study were all at or close to those
positions, it can be speculated that missense mutations
at those residues could alter the binding affinity and/or
specificity between A and B subunits and, thus, affect
substrate recognition and/or phosphatase activity. All
mutations identified in the previous and present studies
were heterozygous missense mutations, which suggests
a dominant attribute of PPP2R1A mutations in cancer
pathogenesis. The mutated subunit A proteins encoded
by mutant PPP2R1A may compete with their wild-type
counterparts in binding to subunit B and forming a stable
and functional enzyme complex. As a result, the enzymatic activity of protein phosphatase 2A, which may be
important for tumor suppression, is reduced in the presence of mutant PPP2R1A proteins. This is the preferred
interpretation, although there are other possibilities. For
example, PPP2R1A may have a tumor-suppressor function, and the mutant proteins may function in a dominant
negative manner. Additional studies should be undertaken to clarify the biological role of mutant PPP2R1A
proteins in cancer development.
In summary, the present study provides new evidence
of PPP2R1A mutations in several histologic subtypes of
ovarian and uterine neoplasms in addition to ovarian
clear-cell carcinoma. The relatively high frequency of
PPP2R1A mutations in uterine (type II) serous carcinomas suggests that the alterations in the protein phosphatase 2A pathway may participate in its pathogenesis,
which is different from ovarian (type II) high-grade serous
carcinoma. The observation that all PPP2R1A mutations
involve the ␣-helix repeats between the interface of subunits A and B strongly suggests that binding of both
subunits is critical in cancer development. Considered
together, the results indicate that PPP2R1A is a new
cancer-associated gene that deserves further functional
exploration to understand the roles of mutations in this
gene in regulating protein phosphatase 2A functions and
in tumor development.
References
1. Jones S, Wang TL, Shih IM, Mao TL, Nakayama K, Roden R, Glas R,
Slamon D, Diaz LA Jr, Vogelstein B, Kinzler KW, Velculescu VE,
Papadopoulos N: Frequent mutations of chromatin remodeling gene
ARID1A in ovarian clear cell carcinoma. Science 2010, 330:228 –231
2. Wera S, Hemmings BA: Serine/threonine protein phosphatases.
Biochem J 1995, 311(Pt 1):17–29
3. Walter G, Mumby M: Protein serine/threonine phosphatases and cell
transformation. Biochim Biophys Acta 1993, 1155:207–226
4. Walter G, Ruediger R, Slaughter C, Mumby M: Association of protein
phosphatase 2A with polyoma virus medium tumor antigen. Proc Natl
Acad Sci USA 1990, 87:2521–2525
5. Di Cristofano A, Ellenson LH: Endometrial carcinoma. Annu Rev
Pathol 2007, 2:57– 85
6. Cho KR, Shih IM: Ovarian cancer. Annu Rev Pathol Mech Dis 2009,
4:287–313
7. Shih I-M, Kurman RJ: Ovarian tumorigenesis: a proposed model
based on morphological and molecular genetic analysis. Am J Pathol
2004, 164:1511–1518
8. Kuo KT, Mao TL, Jones S, Veras E, Ayhan A, Wang TL, Glas R,
Slamon D, Velculescu VE, Kuman RJ, Shih IM: Frequent activating
mutations of PIK3CA in ovarian clear cell carcinoma. Am J Pathol
2009, 174:1597–1601
9. Kuo K, Mao T, Feng Y, Nakayama K, Chen X, Wang Y, Glas R, Ma M,
Kurman RJ, Shih IM, Wang TL: DNA copy number profiles in affinitypurified ovarian clear cell carcinoma. Clin Cancer Res 2010, 16:
1997–2008
10. Kuo KT, Guan B, Feng Y, Mao TL, Chen X, Jinawath N, Wang Y, Kurman
RJ, Shih IM, Wang TL: Analysis of DNA copy number alterations in
ovarian serous tumors identifies new molecular genetic changes in
low-grade and high-grade carcinomas. Cancer Res 2009, 69:4036 –
4042
11. Ahmed AA, Etemadmoghadam D, Temple J, Lynch AG, Riad M,
Sharma R, Stewart C, Fereday S, Caldas C, Defazio A, Bowtell D,
Brenton JD: Driver mutations in TP53 are ubiquitous in high grade
serous carcinoma of the ovary. J Pathol 2010, 221:49 –56
12. Salani R, Kurman RJ, Giuntoli R II, Gardner G, Bristow R, Wang TL,
Shih IM: Assessment of TP53 mutation using purified tissue samples
of ovarian serous carcinomas reveals a higher mutation rate than
previously reported and does not correlate with drug resistance. Int J
Gynecol Cancer 2008, 18:487– 491
13. Shih Ie M, Wang TL: Apply innovative technologies to explore cancer
genome. Curr Opin Oncol 2005, 17:33–38
14. Jones S, Zhang X, Parsons DW, Lin JC, Leary RJ, Angenendt P, Mankoo
P, Carter H, Kamiyama H, Jimeno A, Hong SM, Fu B, Lin MT, Calhoun
ES, Kamiyama M, Walter K, Nikolskaya T, Nikolsky Y, Hartigan J, Smith
DR, Hidalgo M, Leach SD, Klein AP, Jaffee EM, Goggins M, Maitra A,
Iacobuzio-Donahue C, Eshleman JR, Kern SE, Hruban RH, Karchin R,
Papadopoulos N, Parmigiani G, Vogelstein B, Velculescu VE, Kinzler
KW: Core signaling pathways in human pancreatic cancers revealed by
global genomic analyses. Science 2008, 321:1801–1806
15. Rajagopalan H, Bardelli A, Lengauer C, Kinzler KW, Vogelstein B,
Velculescu VE: Tumorigenesis: rAF/RAS oncogenes and mismatchrepair status. Nature 2002, 418:934
PPP2R1A Mutations in Gynecologic Cancers
1447
AJP April 2011, Vol. 178, No. 4
16. Singer G, Oldt R III, Cohen Y, Wang BG, Sidransky D, Kurman RJ,
Shih IM: Mutations in BRAF and KRAS characterize the development
of low-grade ovarian serous carcinoma. J Natl Cancer Inst 2003,
95:484 – 486
17. Lee KR, Nucci MR: Ovarian mucinous and mixed epithelial carcinomas of mullerian (endocervical-like) type: a clinicopathologic analysis
of four cases of an uncommon variant associated with endometriosis.
Int J Gynecol Pathol 2003, 22:42–51
18. Moriya T, Mikami Y, Sakamoto K, Endoh M, Takeyama J, Suzuki T, Mochizuki S, Watanabe M, Monobe Y, Sasano H: Endocervical-like mucinous borderline tumors of the ovary: clinicopathological features and
electron microscopic findings. Med Electron Microsc 2003, 36:240 –246
19. Dube V, Roy M, Plante M, Renaud MC, Tetu B: Mucinous ovarian
tumors of mullerian-type: an analysis of 17 cases including borderline
tumors and intraepithelial, microinvasive, and invasive carcinomas.
Int J Gynecol Pathol 2005, 24:138 –146
20. Kim KR, Choi J, Hwang JE, Baik YA, Shim JY, Kim YM, Robboy SJ:
Endocervical-like (mullerian) mucinous borderline tumours of the
21.
22.
23.
24.
ovary are frequently associated with the KRAS mutation. Histopathology 2010, 57:587–596
Chen W, Arroyo JD, Timmons JC, Possemato R, Hahn WC: Cancerassociated PP2A Aalpha subunits induce functional haploinsufficiency and tumorigenicity. Cancer Res 2005, 65:8183– 8192
Puustinen P, Junttila MR, Vanhatupa S, Sablina AA, Hector ME,
Teittinen K, Raheem O, Ketola K, Lin S, Kast J, Haapasalo H, Hahn
WC, Westermarck J: PME-1 protects extracellular signal-regulated
kinase pathway activity from protein phosphatase 2A-mediated
inactivation in human malignant glioma. Cancer Res 2009, 69:
2870 –2877
Cho US, Xu W: Crystal structure of a protein phosphatase 2A heterotrimeric holoenzyme. Nature 2007, 445:53–57
Ruediger R, Fields K, Walter G: Binding specificity of protein phosphatase 2A core enzyme for regulatory B subunits and T antigens.
J Virol 1999, 73:839 – 842