Sox2: A possible driver of the basal-like phenotype in sporadic breast cancer

Laboratory of Breast and Gynaecological Cancer, Molecular Pathology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain.
Modern Pathology (Impact Factor: 6.19). 04/2007; 20(4):474-81. DOI: 10.1038/modpathol.3800760
Source: PubMed
Tumours arising in BRCA1 mutation carriers and sporadic basal-like breast carcinomas have similar phenotypic, immunohistochemical and clinical characteristics. SOX2 is an embryonic transcription factor located at chromosome 3q, a region frequently gained in sporadic basal-like and BRCA1 germline mutated tumours. The aim of the study was to establish whether sox2 expression was related to basal-like sporadic breast tumours. Two hundred and twenty-six sporadic node-negative invasive breast carcinomas were immunohistochemically analysed for oestrogen receptor (ER), progesterone receptor (PR), CK5/6, EGFR, vimentin, HER2, ki67, p53 and sox2 using tissue microarrays. Tumours were considered to have basal-like phenotype if they were ER/HER2-negative and CK5/6 and/or EGFR-positive. Thirty cases of this series (13.7%) displayed a basal-like phenotype. Sox2 expression was observed in 16.7% of cases and was significantly more frequently expressed in basal-like breast carcinomas (43.3% in basal-like, 10.6% in luminal and 13.3% in HER2+ tumours, P<0.001). Moreover, Sox2 showed a statistically significant inverse association with ER and PR (P=0.001 and 0.017, respectively) and direct association with CK5/6, EGFR and vimentin (P=0.022, 0.005 and <0.001, respectively). Sox2 is preferentially expressed in tumours with basal-like phenotype and may play a role in defining their less differentiated/'stem cell' phenotypic characteristics.


Available from: Yolanda Rodríguez-Gil, Aug 14, 2014
Sox2: a possible driver of the basal-like
phenotype in sporadic breast cancer
Socorro M Rodriguez-Pinilla
, David Sarrio
, Gema Moreno-Bueno
Yolanda Rodriguez-Gil
, Miguel A Martinez
, Lucia Hernandez
, David Hardisson
Jorge S Reis-Filho
and Jose Palacios
Laboratory of Breast and Gynaecological Cancer, Molecular Pathology Programme, Centro Nacional de
Investigaciones Oncolo
gicas (CNIO), Madrid, Spain;
The Breakthrough Breast Cancer Research Centre,
Institute of Cancer Research, London, UK;
Pathology Department, Hospital Universitario 12 de octubre,
Madrid, Spain and
Pathology Department, Hospital Universitario La Paz, Madrid, Spain
Tumours arising in BRCA1 mutation carriers and sporadic basal-like breast carcinomas have similar
phenotypic, immunohistochemical and clinical characteristics. SOX2 is an embryonic transcription factor
located at chromosome 3q, a region frequently gained in sporadic basal-like and BRCA1 germline mutated
tumours. The aim of the study was to establish whether sox2 expression was related to basal-like sporadic
breast tumours. Two hundred and twenty-six sporadic node-negative invasive breast carcinomas were
immunohistochemically analysed for oestrogen receptor (ER), progesterone receptor (PR), CK5/6, EGFR,
vimentin, HER2, ki67, p53 and sox2 using tissue microarrays. Tumours were considered to have basal-like
phenotype if they were ER/HER2-negative and CK5/6 and/or EGFR-positive. Thirty cases of this series (13.7%)
displayed a basal-like phenotype. Sox2 expression was observed in 16.7% of cases and was significantly more
frequently expressed in basal-like breast carcinomas (43.3% in basal-like, 10.6% in luminal and 13.3% in HER2 þ
tumours, Po0.001). Moreover, Sox2 showed a statistically significant inverse association with ER and PR
(P ¼ 0.001 and 0.017, respectively) and direct association with CK5/6, EGFR and vimentin (P ¼ 0.022, 0.005 and
o0.001, respectively). Sox2 is preferentially expressed in tumours with basal-like phenotype and may play a
role in defining their less differentiated/‘stem cell’ phenotypic characteristics.
Modern Pathology (2007) 20, 474–481. doi:10.1038/modpathol.3800760; published online 2 March 2007
SOX2; basal-like phenotype; node-negative breast carcinomas; immunohistochemistry; tissue
Breast cancer is a heterogeneous disease encom-
passing a wide variety of pathological entities and a
range of clinical behaviour.
Recent cDNA micro-
array studies have demonstrated that breast cancers
can be classified according to their gene expression
profiles into four main groups: basal-like, luminal
(A and B), HER2 þ and normal breast-like carcino-
Importantly, these groups have been shown
to be of prognostic and predictive significance.
Basal-like breast carcinomas are of high grade, lack
oestrogen receptor (ER) and HER2 expression, and
are consistently positive for basal keratins and/or
other markers normally expressed by basal/myoe-
pithelial cells.
Moreover, they characteristically
overexpress cyclin E and show p53 immunoexpres-
sion. Historically, this phenotype was associated to
breast carcinomas with a characteristic pattern of
growth (consisting of a central area of necrosis and/
or fibroelastosis surrounded by a ribbon of neoplas-
tic growing at the periphery), and showing a poor
prognosis and a peculiar proclivity for visceral
metastasis, mainly to the lung and brain.
Recently, several studies
have demonstrated
that basal-like carcinomas are characterised at the
histological level by the presence of central scar,
tumour necrosis, high proliferation rates, metaplas-
tic elements (ie, spindle and squamous cells) and
atypical medullary features. Therefore, it is not
surprising that both metaplastic and typical/atypical
medullary carcinomas have also been shown to
belong to this subgroup of tumours.
Received 13 November 2006; revised 16 January 2007; accepted
18 January 2007; published online 2 March 2007
Correspondence: Dr SM Rodrı
guez-Pinilla, MD, Laboratory of
Breast and Gynaecological Cancer, Molecular Pathology Pro-
gramme, Centro Nacional de Investigaciones Oncolo
gicas (CNIO),
Melchor Ferna
ndez Almagro, 28029 Madrid, Spain.
E-mail: or
Current address: Dr J Palacios, Servicio de Anatomı
a Patolo
HHUU Virgen del Rocı
o, Manuel Siurot S/N, 41013 Sevilla,
Modern Pathology (2007) 20, 474481
2007 USCAP, Inc All rights reserved 0893-3952/07
Page 1
The similarities between basal-like breast carci-
nomas and tumours arising in BRCA1 germline
mutation carriers are overwhelming.
tumours clustered together with sporadic basal-like
tumours in cDNA microarrays studies.
these tumours also share immunohistochemical,
morphological and biological characteristics, in-
cluding the predisposition to visceral metastasis
and better response to chemotherapy than other
subgroup of tumours.
On the basis of these
lines of evidence, many authors have suggested
that BRCA1 gene and/or BRCA1 pathway
inactivated in basal-like sporadic tumours, which
has been confirmed recently.
SOX2 gene, located in chromosome 3q26.33,
encodes for a member of the HMG-domain DNA-
binding protein family. It has been demonstrated
recently that sox2 may control the expression of
several genes that play pivotal roles in embryonic
development, including nanog homeobox, nestin,
d-crystalline, fibroblast growth factor 4, undifferen-
tiated embryonal cell transcription factor 1 and
F-box containing protein 15. Moreover, its function
is highly related to the expression of the POU
domain class 5 transcription factor 1 (aka, OCT-4),
another gene implicated in maintaining stem cell
properties. SOX2 downregulation correlates with
loss of pluripotency and self-renewal, and the
activation of subsequent differentiation steps.
Furthermore, SOX2 has been implicated as a target
of WNT, TGFB, FGF, BMP and NODAL signalling
pathways during embryogenesis.
SOX2 gene
expression has not been studied in breast cancer;
however, gains of genomic material on the long arm
of chromosome 3 (3q) are frequently found in
tumours arising in BRCA1 germ-line mutation
and in sporadic basal-like breast cancer.
Although there is no internationally agreement
about the immunohistochemical definition of spora-
dic basal-like breast carcinomas, Nielsen et al
demonstrated that a panel of four antibodies (ER,
HER2, CK5/6 and EGFR) identifies these tumours
with high specificity. Given the role played by sox2
in the maintenance of stem cells and the fact that
basal-like cancers express multiple lineage markers
(ie, luminal and basal keratins, vimentin, myoid
markers) and frequently display metaplastic ele-
ments, we hypothesised that sox2 would be pre-
ferentially expressed in this subgroup of breast
carcinomas. The aim of this study was to determine
whether sox2 protein expression correlates with
basal-like phenotype, according to Nielsen et al.
in a cohort of 226 node-negative invasive
breast carcinomas.
Materials and methods
Tumour Samples
We analysed a group of 226 node-negative sporadic
breast carcinomas diagnosed in Hospital Universi-
tario La Paz, Madrid between 1988 and 2002. None
of the patients had family history suggestive of
familial/hereditary cancer.
Some of the clinico-
pathological characteristics of this series, including
age, treatment, survival of the patients, as well as
size, grade, histological subtype and some immuno-
histochemical characteristics of the tumours (oestro-
gen (ER) and progesterone receptors (PR), ki67,
p53, HER2, CK5/6, EGFR and vimentin) have been
reported previously.
The study was carried out
with the approval of the ‘Hospital La Paz’ ethical
Tissue Microarray Construction
Representative areas from formalin-fixed, paraffin-
embedded infiltrating carcinomas and 30 samples
from non-neoplastic breast tissue were carefully
selected on H&E-stained sections and two 1-mm-
diameter tissue cores were obtained from each
specimen. The tissue cores were precisely arrayed
into a new paraffin block using a tissue microarray
workstation (Beecher Instruments, Silver Spring, MD).
Immunohistochemical staining on tissue microarray
(TMAs) sections was performed using the EnVision
method as described previously. Antibodies, clones,
dilutions, antigen-retrieval methods and scoring
systems for ER, PR, HER2, CK5/6, EGFR, vimentin,
ki67 and p53 are described elsewhere.
anti-sox2 polyclonal antibody was applied at dilu-
tion of 1:100 (sox2, Stem-cell Technologies). After a
preheating step for antigen retrieval, TMA sections
were immersed in boiling 10 mmol/l sodium citrate
at pH 6.5 for 2 min in a pressure cooker. Cases were
considered positive for sox2 when any unequivocal
neoplastic cell displayed definite nuclear staining.
Normal breast control cores on the TMA were used
as internal controls. Positive (ie, normal breast
tissue) and negative controls (ie, omission of the
primary antibody and/or IgG-matched serum) were
included in each slide run.
Tumours were subdivided according to the Niel-
sen et al classification as: basal-like (ER and HER2-
negative and CK5/6 and/or EGFR-positive), luminal
(ER-positive and HER2-negative) and HER2-positive
Statistical Analysis
To test associations between categorical variables
we used the w
or Fisher’s exact test. Values of
Po0.05 were considered significant. All tests were
two-tailed and 95% confidence intervals were
adopted. These analyses were carried out using the
SPSS 12.0 for Windows statistical program (SPSS
Inc., Chicago, IL).
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 2
The correlations between sox2 expression, clinico-
pathological features and immunohistochemical
markers studied in this series are summarised in
Table 1.
Using the criteria proposed by Nielsen et al,
cases (13.7%), 17 (7.8%) and 156 (71.2%) were
classified as basal-like, HER2 and luminal cancers,
respectively. Sixteen cases (7.3%) did not fulfil any
of the above criteria and were excluded from the
analysis. Sox2 nuclear expression was found in
33/198 (16.7%) node-negative breast carcinomas.
Basal-like breast carcinomas showed a statistically
significant higher prevalence of sox2 expression
when compared to that seen in the other groups
(Table 1, Figure 1): 13/30 basal-like breast carcino-
mas (43.3%) displayed sox2 immunoreactivity,
whereas sox2 expression was seen in only 13.3%
(2/15) of HER2 tumours and in 10.6% (14/132) of
luminal tumours cancers (Po0.0001).
Sox2 expression was directly correlated with
tumour size and expression of CK5/6, EGFR and
vimentin, and inversely correlated with ER and PR
Taken together, these findings demonstrate that
sox2 is preferentially expressed in basal-like carci-
nomas. However, in a way akin to other proteins
involved in the biology of basal-like carcinomas
(eg, caveolin 1,
), sox2 expression is
not restricted to basal-like cancers, given that up to
10% of ER-positive tumours and up to 13% of
HER2 þ showed positivity for sox2.
It has been demonstrated that tumours arising in
BRCA1 germline mutation carriers show significant
histological, immunohistochemical expression pro-
file and molecular genetic differences when com-
pared to sporadic breast carcinomas. However, with
the more comprehensive characterisation of basal-
like breast carcinomas, it has become clear that
tumours arising in BRCA1 germline mutation car-
riers and sporadic basal-like breast carcinomas have
genotypic and phenotypic traits that are remarkably
Comparative genomic hybridisation (CGH) analy-
sis has demonstrated that 3q copy number gains
were an independent predictor of poor prognosis
in a cohort of 76 sporadic node-negative breast
and that these gains are significantly more
prevalent in tumours arising in BRCA1 mutation
In addition, gains of the telomeric
region of 3q are seen in approximately 20% of
basal-like cancers and 10% of luminal tumours.
Sox2, a transcription factor located on 3q26.3-q27,
is one of the transcription factors expressed by stem
cells. There is growing evidence to suggest that this
gene is essential for the maintenance of stem cell
proliferation and differentiation capabilities, and it
is not expressed in mature differentiated cells.
Its role in carcinogenesis is poorly understood,
although deregulation of homeobox gene expression
has been implicated in the determining phenotypic
expression of gastric, ampullar and pancreatic
neoplastic cells and in the biology of cancers arising
in these anatomical sites.
Furthermore, expres-
sion analysis studies have shown that SOX2 is
one of the genes differentially expressed between
embryonal carcinomas and seminomas. Previous
have suggested that neoplastic cells of
seminomas have phenotypic characteristics similar
to those of undifferentiated germ cells, whereas
embryonal carcinoma cells resemble pluripotent
embryonic stem cells, which have the ability to
Moreover, SOX2 has been shown
recently to be amplified in prostate cancers.
In our series, sox2 nuclear expression was
strongly associated with basal-like phenotype
(Po0.001). Bertucci et al
have demonstrated a
highly significant overrepresentation of genes lo-
cated on 12p13 and 6p21.3 in basal-like tumours,
including several genes related to stem cell biology,
such as NANOG, GDF3, STELLA, DPPA3, CD9 and
EDR and OCT4/POU5F1, respectively. 12p13 cyto-
genetic band is reported to be a hots-pot region for
structural chromosomal changes associated with
germ cell tumours.
Although previous chromoso-
mal CGH studies did not reveal gains of genomic
material on 12p13 and/or 6p21.3 as a frequent event
in basal-like and BRCA1 tumours,
more recent
array CGH and fluorescent in situ hybridisation
analysis have demonstrated that gains of genomic
material on 6p21 and amplification of 12p13 are
preferentially found in basal-like breast cancers.
These discrepancies may be because of the low
resolution of chromosomal CGH and to the different
definitions for basal-like cancers employed in
these studies.
Interestingly, some of stem
cell-related genes mapping to 12p13, are reported to
be upregulated by SOX2 gene expression and, on
the other hand, sox2 is directly regulated by
which maps to 6p21. Taken to-
gether, these findings suggest that in both sporadic
basal-like carcinomas and tumours arising in BRCA1
germline mutation carriers, sox2 expression may be
either driven by SOX2 gene copy number gains or
OCT4 gene-mediated SOX2 transcriptional activa-
tion. Therefore, it seems clear that further studies
are required to clarify the mechanism of sox2
expression in basal-like breast cancers.
Sox2 expression in our series was strongly
correlated to CK5/6, EGFR and vimentin immuno-
reactivity. Both CK5/6 and EGFR proteins have been
reported to be expressed by both normal mammary
myoepithelial and epithelial cells
and, when
included in a immunohistochemical panel together
with ER and HER2, these proteins define with high
specificity the basal-like phenotype in both sporadic
and in tumour arising in BRCA1 germline mutation
Vimentin is highly characteristic of
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 3
all immature primitive cells, and in normal breast its
expression is restricted to mesenchymal and myoe-
pithelial cells.
Its expression in breast tumours
has been also related to a basal-like phenotype in
both sporadic and familial tumours.
explanations have been put forward for the exis-
tence of breast cancers expressing both myoepithe-
lial/mesenchymal and luminal markers: some have
suggested that these lesions have a ‘stem cell
phenotype’ and therefore would be able to be
different towards different lineages, whereas others
have speculated that this may reflect the ability of
these cells to undergo epithelial–mesenchymal
transition or to activate a basal/myoepithelial differ-
entiation programme.
Given the previously reported functions of SOX2,
our results suggest that sox2 expression may play a
role in conferring a less differentiated phenotype in
these tumours or to activate the ability to differenti-
ate in both luminal and basal/myoepithelial
In conclusion, our findings suggest that sox2
expression, a stem cell transcription factor, located
in a frequently gained genomic region of BRCA1
Table 1 Correlations between sox2 expression and clinicopathological and immunohistochemical features in node-negative breast
Sox2 negative (n ¼ 165) Sox2 positive (n ¼ 33) P
Menopausal status 70/84 (83.3%) 14/84 (16.7%)
Premenopausal 88/106 (83.0%) 18/106 (17.0%) 1
p T1 86/98 (87.8%) 12/98 (12.2%)
p T2 49/67 (73.1%) 18/67 (26.9%) 0.023
Histological grade
Grade 1 43/45 (95.6%) 2/45 (4.4%)
Grade 2 40/49 (81.6%) 9/49 (18.4%)
Grade 3 65/81 (80.2%) 16/81 (19.8%) 0.059
Clinical phenotype
Basal-like 17/30 (56.7%) 13/30 (43.3%)
Luminal 118/132 (89.4%) 14/132 (10.6%)
HER2+ 13/15 (86.7%) 2/15 (13.3%) o0.001
Oestrogen receptor
Negative 41/59 (69.5%) 18/59 (30.5%)
Positive 123/138 (89.1%) 15/138 (10.9%) 0.001
Progesterone receptor
Negative 52/70 (74.3%) 18/70 (25.7%)
Positive 111/126 (88.1%) 15/126 (11.9%) 0.017
Negative 151/182 (83.0%) 31/182 (17.0%)
Positive 14/16 (87.5%) 2/16 (12.5%) 0.1
Negative 118/139 (84.6%) 21/139 (15.1%)
Positive 45/57 (78.9%) 12/57 (21.1%) 0.4
Negative 132/156 (84.6%) 24/156 (15.4%)
Positive 33/42 (78.6%) 9/42 (21.4%) 0.356
Negative 149/173 (86.1%) 24/173 (13.9%)
Positive 11/19 (57.9%) 8/19 (42.1%) 0.005
Negative 140/162 (86.4%) 22/162 (13.6%)
Positive 24/35 (68.6%) 11/35 (31.4%) 0.022
Negative 132/148 (89.2%) 16/148 (10.8%)
Positive 32/49 (65.3%) 17/49 (34.7%) o0.001
CK5/6: cytokeratin 5/6; EGFR: epidermal growth factor receptor.
According to the Nielsen et al criteria
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 4
familial cancers and sporadic basal-like cancers,
may play a role in the biology of basal-like breast
This study was supported by the Spanish Ministry
of Education and Science (SAF2004-08258-C02-01)
and the Instituto de Salud Carlos III (PI051890).
Socorro Marı
a Rodrı
guez-Pinilla and David Sarrio
are recipients of research grants from the Fondo
de Investigacio
n Sanitaria, Spain. Gema Moreno
Bueno is a junior investigator of the Ramo
n y Cajal
Programme (2004).
1 Perou CM, Sorlie T, Eisen MB, et al. Molecular
portraits of human breast tumours. Nature 2000;406:
2 Sorlie T, Perou CM, Tibshirani R, et al. Gene expres-
sion patterns of breast carcinomas distinguish tumor
subclasses with clinical implications. Proc Natl Acad
Sci USA 2001;98:10869–10874.
3 Sorlie T, Tibshirani R, Parker J, et al. Repeated
observation of breast tumor subtypes in independent
gene expression data sets. Proc Natl Acad Sci USA
4 Sotiriou C, Neo SY, McShane LM, et al. Breast cancer
classification and prognosis based on gene expression
profiles from a population-based study. Proc Natl Acad
Sci USA 2003;100:10393–10398.
5 Gusterson BA, Ross DT, Heath VJ, et al. Basal
cytokeratins and their relationship to the cellular
origin and functional classification of breast cancer.
Breast Cancer Res 2005;7:143–148.
6 Nielsen TO, Hsu FD, Jensen K, et al. Immunohisto-
chemical and clinical characterisation of the basal-like
subtype of invasive breast carcinoma. Clin Cancer Res
7 Abd El-Rehim DM, Ball G, Pinder SE, et al. High-
throughput protein expression analysis using tissue
microarray technology of a large well-characterised
series identifies biologically distinct classes of breast
Figure 1 Expression of proteins studied by immunohistochemistry on tissue microarrays. Expression of sox2 (a), ki67 (b), vimentin (c)
and CK5/6 (d), in one case of sporadic, lymph node negative, grade 3 invasive ductal carcinoma with basal-like phenotype. Original
magnification: (a) 400; and (bd) 200.
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 5
cancer confirming recent cDNA expression analyses.
Int J Cancer 2005;116:340–350.
8 Abd El-Rehim DM, Pinder SE, Paish CE, et al.
Expression of luminal and basal cytokeratins in human
breast carcinoma. J Pathol 2004;203:661–671.
9 Livasy CA, Karaca G, Nanda R, et al. Phenotypic
evaluation of the basal-like subtype of invasive breast
carcinoma. Mod Pathol 2006;19:264–271.
10 van de Rijn M, Perou CM, Tibshirani R, et al.
Expression of cytokeratins 17 and 5 identifies a group
of breast carcinomas with poor clinical outcome. Am J
Pathol 2002;161:1991–1996.
11 Banerjee S, Reis-Filho JS, Ashley S, et al. Basal-like
breast carcinomas: clinical outcome and response to
chemotherapy. J Clin Pathol 2006;59:729–735.
12 Gamallo C, Moreno-Bueno G, Sarrio D, et al. The
prognostic significance of P-cadherin in infiltrating
ductal breast carcinoma. Mod Pathol 2001;14:650–654.
13 Rouzier R, Perou CM, Symmans WF, et al. Breast
cancer molecular subtypes respond differently to
preoperative chemotherapy. Clin Cancer Res 2005;11:
14 Rodriguez-Pinilla SM, Sarrio D, Honrado E, et al.
Prognostic significance of basal-like phenotype and
fascin expression in node-negative invasive breast
carcinomas. Clin Cancer Res 2006;12:1533–1539.
15 Palacios J, Benito N, Pizarro A, et al. Anomalous
expression of P-cadherin in breast carcinoma. Correla-
tion with e-cadherin expression and pathological
features. Am J Pathol 1995;146:605–612.
16 Rakha EA, Putti TC, Abd El-Rehim DM, et al.
Morphological and immunophenotypic analysis of
breast carcinomas with basal and myoepithelial differ-
entiation. J Pathol 2006;208:495–506.
17 Tsuda H, Takarabe T, Hasegawa F, et al. Large, central
acellular zones indicating myoepithelial tumor differ-
entiation in high-grade invasive ductal carcinomas as
markers of predisposition to lung and brain metas-
tases. Am J Surg Pathol 2000;24:197–202.
18 Fulford LG, Easton DF, Reis-Filho JS, et al. Specific
morphological features predictive for the basal pheno-
type in grade 3 invasive ductal carcinoma of breast.
Histopathology 2006;49:22–34.
19 Reis-Filho JS, Milanezi F, Steele D, et al. Metaplastic
breast carcinomas are basal-like tumours. Histopatho-
logy 2006;49:10–21.
20 Jacquemier J, Padovani L, Rabayrol L, et al. Typical
medullary breast carcinomas have a basal/myoepithe-
lial phenotype. J Pathol 2005;207:260–268.
21 Laakso M, Loman N, Borg A, et al. Cytokeratin 5/14-
positive breast cancer: true basal phenotype confined
to BRCA1 tumors. Mod Pathol 2005;18:1321–1328.
22 Foulkes WD, Brunet JS, Stefansson IM, et al. The
prognostic implication of the basal-like (cyclin E high/
p27 low/p53+/glomeruloid-microvascular-prolifera-
tion+) phenotype of BRCA1-related breast cancer.
Cancer Res 2004;64:830–835.
23 Turner N, Reis-Filho JS. Basal-like breast cancer
and the BRCA1 phenotype. Oncogene 2006;25:5846–
24 Palacios J, Honrado E, Osorio A, et al. Re: Germline
BRCA1 mutations and a basal epithelial phenotype in
breast cancer. J Natl Cancer Inst 2004;96:712–714;
author reply 4.
25 Robson ME, Chappuis PO, Satagopan J, et al. A
combined analysis of outcome following breast cancer:
differences in survival based on BRCA1/BRCA2 muta-
tion status and administration of adjuvant treatment.
Breast Cancer Res 2004;6:R8–R17.
26 Chappuis PO, Goffin J, Wong N, et al. A significant
response to neoadjuvant chemotherapy in BRCA1/2
related breast cancer. J Med Genet 2002;39:608–610.
27 Turner N, Tutt A, Ashworth A. Hallmarks of ‘BRCA-
ness’ in sporadic cancers. Nat Rev Cancer 2004;4:
28 Turner N, Reis-Filho JS, Russel AM, et al. BRCA1
down-regulation in sporadic basal-like breast cancer.
Oncogene 2006;1–7.
29 Graham V, Khudyakov J, Ellis P, et al. Sox2 functions to
maintain neural progenitor identity. Neuron
30 D’Amour KA, Gage FH. Genetic and functional
differences between multipotent neuronal and plur-
ipotent embryonic stem cells. Proc Natl Acad Sci USA
31 Chickarman V, Troein C, Nuber UA, et al. Transcrip-
tional dynamics of the embryonic stem cell switch.
PLoS Comput Biol 2006;2:1080–1092.
32 Hemmati HD, Nakano I, Lazareff JA, et al. Cancerous
stem cells can arise from pediatric brain tumors. Proc
Natl Acad Sci USA 2003;9:15178–15183.
33 Carlin R, Davis D, Weiss M, et al. Expression of early
transcription factors Oct4, Sox2 and Nanog by porcine
umbilical cord (PUC) matrix cells. Reprod Biol
Endocrinol 2006;4:8.
34 Katoh Y, Katoh M. Comparative genomics on SOX2
orthologs. Oncol Rep 2005;14:797–800.
35 Kuroda T, Tada M, Kubota H, et al. Octamer and Sox
elements are required for transcriptional cis regulation
of Nanog gene expression. Mol Cell Biol 2005;25:
36 Chew JL, Loh YH, Zhang W, et al. Reciprocal
transcriptional regulation of Pou5f1 and Sox2 via the
Oct4/Sox2 complex in embryonic stem cells. Mol Cell
Biol 2005;25:6031–6046.
37 Mansukhani A, Ambrosetti D, Holmes G, et al. Sox2
induction by FGF and FGFR2 activating mutations
inhibits Wnt signaling and osteoblast differentiation.
J Cell Biol 2005;168:1065–1076.
38 Takemoto T, Uchikawa M, Kamachi Y, et al. Conver-
gence of Wnt and FGF signals in the genesis of
posterior neural plate through activation of the sox2
enhancer N-1. Development 2006;133:297–306.
39 Korkola JE, Houldsworth J, Chadalavada RSV, et al.
Down-regulation of stem cell genes, including those in
a 200-kb gene cluster at 12p13.3, is associated with in
vivo differentiation of human male germ cell tumors.
Cancer Res 2006;66:820–827.
40 Rao M. Conserved and divergent paths that regulate
self-renewal in mouse and human embryonic stem
cells. Dev Biol 2004;275:269–286.
41 van Raag TJ, Moore KB, Iordanova I, et al. Frizzled 5
signaling governs the neural potential of progenitors
in the developing Xenopus retina. Neuron 2005;46:
42 Wessels LF, van Welsem T, Hart AA, et al. Molecular
classification of breast carcinomas by comparative
genomic hybridization: a specific somatic genetic pro-
file for BRCA1 tumors. Cancer Res 2002;62:7110–7117.
43 van Beers EH, van Welsem T, Wessels LF, et al.
Comparative genomic hybridization profiles in human
BRCA1 and human BRCA2 breast tumors highlight
differential sets of genomic aberrations. Cancer Res
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 6
44 Bergmaschi A, Kim YH, Wang P, et al. Distinct patterns
of DNA copy number alteration are associated with
different clinicopathological features and gene-expres-
sion subtypes of breast cancer. Genes Chromosomes
Cancer 2006;45:1033–1040.
45 Palacios J, Honrado E, Osorio A, et al. Immunohisto-
chemical characteristics defined by tissue microarray
of hereditary breast cancer not attributable to BRCA1
or BRCA2 mutations: differences from breast carcino-
mas arising in BRCA1 and BRCA2 mutation carriers.
Clin Cancer Res 2003;9:3606–3614.
46 Rodrı
guez-Pinilla SM, Sarrio
D, Honrado E, et al.
Vimentin and laminin expression is associated with
basal-like phenotype in both sporadic and BRCA1-
associated breast carcinomas. J Clin Pathol 2006,
(published on-line 14 November 2006).
47 Pinilla SM, Honrado E, Hardisson D, et al. Caveolin-1
expression is associated with a basal-like phenotype in
sporadic and hereditary breast cancer. Breast Cancer
Res Treat 2006;99:85–90.
48 Simpson PT, Gale T, Reis-Filho JS, et al. Distribution
and significance of 14-3-3 sigma, a novel myoepithelial
marker, in normal, benign, and malignant breast tissue.
J Pathol 2004;202:274–285.
49 Lakhani SR, Van De Vijver MJ, Jacquemier J, et al. The
pathology of familial breast cancer: predictive value of
immunohistochemical markers estrogen receptor, pro-
gesterone receptor, HER-2, and p53 in patients with
mutations in BRCA1 and BRCA2. J Clin Oncol 2002;
50 Lakhani SR, Jacquemier J, Sloane JP, et al. Multi-
factorial analysis of differences between sporadic
breast cancers and cancers involving BRCA1 and
BRCA2 mutations. J Natl Cancer Inst 1998;90:
51 Lakhani SR, Reis-Filho JS, Fulford L, et al. Prediction
of BRCA1 status in patients with breast cancer using
estrogen receptor and basal phenotype. Clin Cancer
Res 2005;11:5175–5180.
52 Foulkes WD, Stefansson IM, Chappuis PO, et al.
Germline BRCA1 mutations and a basal epithelial
phenotype in breast cancer. J Natl Cancer Inst 2003;95:
53 Arnes JB, Brunet JS, Stefansson I, et al. Placental
cadherin and the basal epithelial phenotype of BRCA1-
related breast cancer. Clin Cancer Res 2005;11:4003–
54 Carter MR, Hornick JL, Lester S, et al. Spindle cell
(sarcomatoid) carcinoma of the breast: a clinicopatho-
logic and immunohistochemical analysis of 29 cases.
Am J Surg Pathol 2006;30:300–309.
55 Jones C, Ford E, Gillett C, et al. Molecular cytogenetic
identification of subgroups of grade III invasive ductal
breast carcinomas with different clinical outcomes.
Clin Cancer Res 2004;10:5988–5997.
56 Palacios J, Honrado E, Osorio A, et al. Phenotypic
characterisation of BRCA1 and BRCA2 tumors based in
a tissue microarray study with 37 immunohistochem-
ical markers. Breast Cancer Res Treat 2005;90:
57 Leibl S, Gogg-Kammerer M, Sommersacher A, et al.
Metaplastic breast carcinomas: are they of myoepithe-
lial differentiation? Immunohistochemical profile of
the sarcomatoid subtype using novel myoepithelial
markers. Am J Surg Pathol 2005;29:347–353.
58 Reis-Filho JS, Milanezi F, Paredes J, et al. Novel and
classic myoepithelial/stem cell markers in metaplastic
carcinomas of the breast. Appl Immunohistochem Mol
Morphol 2003;11:1–8.
59 Janssen EA, Baak JP, Guervos MA, et al. In lymph
node-negative invasive breast carcinomas, specific
chromosomal aberrations are strongly associated with
high mitotic activity and predict outcome more
accurately than grade, tumour diameter, and oestrogen
receptor. J Pathol 2003;201:555–561.
60 Boiani M, Scholer HR. Regulatory networks in embryo-
derived pluripotent stem cells. Nat Rev Mol Cell Biol
61 Tsukamoto T, Miroshita T, Tatematsu M. Gastric and
intestinal mixed-type intestinal metaplasia: aberrant
expression of transcription factors and stem cell
intestinalization. Gastric Cancer 2006;9:156–166.
62 Sanada Y, Yoshida K, Konishi K, et al. Expression of
gastric mucin MUC5AC and gastric transcription factor
Sox2 in ampulla of vater adenocarcinoma: comparison
between expression patterns and histologic subtypes.
Oncol Rep 2006;15:1157–1161.
63 Tsukamoto T, Miroshita T, Mihara M, et al. Sox2
expression in human stomach adenocarcinomas with
gastric and gastric-and-intestinal-mixed phenotypes.
Histopathology 2005;46:649–658.
64 Sanada Y, Yoshida K, Ohara M, et al. Histopathologic
evaluation of stepwise progression of pancreatic
carcinoma with immunohistochemical analysis of
gastric epithelial transcription factor Sox2; comparison
of expression patterns between invasive components
and cancerous or nonneoplastic intraductal compo-
nents. Pancreas 2006;32:164–170.
65 Tatematsu M, Tsukamoto T, Inada K. Stem cells and
gastric cancer: role of gastric and intestinal mixed
intestinal metaplasia. Cancer Sci 2003;94:135–141.
66 Li XL, Eishi Y, Bai YQ, et al. Expression of the SRY-
related HMG box protein SOX2 in human gastric
carcinoma. Int J Oncol 2004;24:257–263.
67 Prasad NB, Biankin AV, Fukushima N, et al. Gene
expression profiles in pancreatic intraepithelial neo-
plasia reflect the effects of Hedgehog signaling on
pancreatic ductal epithelial cells. Cancer Res
68 Sattler HP, Lensch R, Rohde V, et al. Novel amplifica-
tion unit at chromosome 3q25–q27 in human prostate
cancer. Prostate 2000;45:207–215.
69 Bertucci F, Finetti P, Cervera N, et al. Gene expression
profiling shows medullary breast cancer is a subgroup
of basal breast cancers. Cancer Res 2006;66:4636–4644.
70 Jones C, Nonni AV, Fulford L, et al. CGH analysis of
ductal carcinoma of the breast with basaloid/myo-
epithelial cell differentiation. Br J Cancer 2001;85:
71 Letessier A, Sirconlomb F, Ginestier C, et al. Fre-
quency, prognostic impact, and subtype association of
8p12, 8q24, 11q13, 12p13, 17q12, and 20q13 amplifi-
cations in breast cancers. BMC Cancer 2006;6:245 (in
72 Monaghan P, Clarke CL, Pernsinghe NP, et al. Epider-
mal growth factor receptor expression on human breast
luminal and basal cells in vitro. Epithelial Cell Biol
73 van Agthoven T, Timmermaus M, Foekens JA, et al.
Differential expression of estrogen, progesterone and
epidermal growth factor receptors in normal, benign,
and malignant human breast tissues using dual
staining immunohistochemistry. Am J Pathol 1994;
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 7
74 Korsching E, Packeisen J, Liedtke C, et al. The origin of
vimentin expression in invasive breast cancer: epithe-
lial–mesenchymal transition, myoepithelial histogen-
esis from progenitor cells with bilinear differentiation
potential? J Pathol 2005;206:451–457.
75 Reis-Filho JS. Re: Korsching et al. The origin of
vimentin expression in invasive breast cancer: epithe-
lial–mesenchymal transition, myoepithelial histo-
genesis or histogenesis from progenitor cells with
bilinear differentiation potential? J Pathol 2005;206:
76 Asselin-Labat M-L, Shackleton M, Stingl J, et al.
Steroid hormone receptor status of mouse mammary
stem cells. J Natl Cancer Inst 2006;98:1011–1014.
SOX2 in sporadic basal-like breast cancer
SM Rodriguez-Pinilla et al
Modern Pathology (2007) 20, 474481
Page 8
  • Source
    • "Sox2, Oct4 and Nanog are traditional embryonic stem cell markers used to reprogram cells to a pluripotent state, and are expressed at elevated levels in BCS L Cs [27, 30, 85, 86]. Sox2 is up-regulated in TNBCs and has been implicated in tumorsphere formation and control of tumor initiation [27, 62, 63] . Therefore , the finding that the AHR directly interacts with the Sox2 promoter (Fig. 4a) strongly suggests that the AHR is at the apex of an important signaling pathway that controls cancer progression by increasing phenotypic and functional expression of cancer stem cell-associated markers within the tumor cell population. "
    [Show abstract] [Hide abstract] ABSTRACT: Self-renewing, chemoresistant breast cancer stem cells are believed to contribute significantly to cancer invasion, migration and patient relapse. Therefore, the identification of signaling pathways that regulate the acquisition of stem-like qualities is an important step towards understanding why patients relapse and towards development of novel therapeutics that specifically target cancer stem cell vulnerabilities. Recent studies identified a role for the aryl hydrocarbon receptor (AHR), an environmental carcinogen receptor implicated in cancer initiation, in normal tissue-specific stem cell self-renewal. These studies inspired the hypothesis that the AHR plays a role in the acquisition of cancer stem cell-like qualities. To test this hypothesis, AHR activity in Hs578T triple negative and SUM149 inflammatory breast cancer cells were modulated with AHR ligands, shRNA or AHR-specific inhibitors, and phenotypic, genomic and functional stem cell-associated characteristics were evaluated. The data demonstrate that (1) ALDH high cells express elevated levels of Ahr and Cyp1b1 and Cyp1a1, AHR-driven genes, (2) AHR knockdown reduces ALDH activity by 80 %, (3) AHR hyper-activation with several ligands, including environmental ligands, significantly increases ALDH1 activity, expression of stem cell- and invasion/migration-associated genes, and accelerates cell migration, (4) a significant correlation between Ahr or Cyp1b1 expression (as a surrogate marker for AHR activity) and expression of stem cell- and invasion/migration-associated gene sets is seen with genomic data obtained from 79 human breast cancer cell lines and over 1,850 primary human breast cancers, (5) the AHR interacts directly with Sox2, a master regulator of self-renewal; AHR ligands increase this interaction and nuclear SOX2 translocation, (6) AHR knockdown inhibits tumorsphere formation in low adherence conditions, (7) AHR inhibition blocks the rapid migration of ALDH high cells and reduces ALDH high cell chemoresistance, (8) ALDH high cells are highly efficient at initiating tumors in orthotopic xenografts, and (9) AHR knockdown inhibits tumor initiation and reduces tumor Aldh1a1, Sox2, and Cyp1b1 expression in vivo. These data suggest that the AHR plays an important role in development of cells with cancer stem cell-like qualities and that environmental AHR ligands may exacerbate breast cancer by enhancing expression of these properties.
    Full-text · Article · Dec 2016 · BMC Biology
  • Source
    • "However, if EMT is inappropriately activated in BC cells, it can induce the formation of migratory mesenchymal cells that possess stem cell-like phenotypes, TICs properties, and an invasive capacity with a high metastatic potential [90, 91] . These similarities have led to the identification of common ES cell markers, such as Nanog, Oct4, and Sox2, as also expressed in mammary tumors929394, significantly increasing the potential of TICs cells to form mammospheres and promote metastatic invasion [47]. Additionally, a Nanog/Oct4/Sox2 expression signature was directly associated with high-grade TNBC basal-like subtype and with poor clinical outcome [95] (Fig. 1). "
    [Show abstract] [Hide abstract] ABSTRACT: Cancer has been considered as temporal and spatial aberrations of normal development in tissues. Similarities between mammary embryonic development and cell transformation suggest that the underlying processes required for mammary gland development are also those perturbed during various stages of mammary tumorigenesis and breast cancer (BC) development. The master regulators of embryonic development Cripto-1, Notch/CSL, and Wnt/β-catenin play key roles in modulating mammary gland morphogenesis and cell fate specification in the embryo through fetal mammary stem cells (fMaSC) and in the adult organism particularly within the adult mammary stem cells (aMaSC), which determine mammary progenitor cell lineages that generate the basal/myoepithelial and luminal compartments of the adult mammary gland. Together with recognized transcription factors and embryonic stem cell markers, these embryonic regulatory molecules can be inappropriately augmented during tumorigenesis to support the tumor-initiating cell (TIC)/cancer stem cell (CSC) compartment, and the effects of their deregulation may contribute for the etiology of BC, in particular the most aggressive subtype of BC, triple-negative breast cancer (TNBC). This in depth review will present evidence of the involvement of Cripto-1, Notch/CSL, and Wnt/β-catenin in the normal mammary gland morphogenesis and tumorigenesis, from fMaSC/aMaSC regulation to TIC generation and maintenance in TNBC. Specific therapies for treating TNBC by targeting these embryonic pathways in TICs will be further discussed, providing new opportunities to destroy not only the bulk tumor, but also TICs that initiate and promote the metastatic spread and recurrence of this aggressive subtype of BC.
    Full-text · Article · Mar 2016 · Breast Cancer Research and Treatment
  • Source
    • "Stem cell populations that may give rise to only limited cell types are multipotent. Cells that give rise to only one cell type are termed unipotent [9, 10] and pluripotent is a cell that can generate cell types from each of the three embryonic germ layers: the mesoderm, ectoderm and endoderm [11]. Progenitor (stem) Cell indicates the cells can be dividing with the capacity to differentiate. "
    Preview · Article · Feb 2016
Show more