Sabato 27 ottobre 2012 - Pacini Editore

PoStER
Identification of cancer stem cells in triple
negative phenotype of breast carcinoma:
comparison between different CSCS markers
M. Di Bonito, F. Collina, G. Scognamiglio, M. D’Aiuto, A. Manna,
V. Relli, L. La Sala, G. Liguori, M. Cantile, G. Botti
Pathology Department, National Cancer Institute “Fondazione G. Pascale”,
Naples, Italy
Triple Negative breast cancer subtype, typically negative for ER,
PgR and HER2, represents about 20% of all breast carcinomas
and has a significant clinical relevance being associated with a
shorter median time to relapse and death and does not respond to
endocrine therapy or other available targeted agents.
According to the CSC hypothesis, in the breast as well as in other
tissues, cancer arises from normal stem cells that undergo oncogenic
transformation. It has been suggested that the increased
aggressiveness of breast cancer as well as resistance to standard
drug therapies may be associated with the presence of stem cell
populations within the tumor, but identifying the ideal molecular
marker for the detection of cancer stem cells in breast cancer
subtypes is rather complex. In fact, contrasting opinions about the
different CSCs markers used in breast cancer and their prognostic
value are present in the literature.
In this study we have selected six different CSCs markers, CD133,
CD338, CD24, CD44, Ck19, and ALDHA1, and evaluated their
expression by immunohistochemistry on a specific Triple Negative
Breast Cancer TMA combined with patient follow-up.
The data obtained allow us only to confirm the inverse correlation
between CD24 and CD44 (p value = 0.043) and a trend of statistical
significance between CD24 and CD338 (p value = 0.065).
However, at least in this specific subtype of breast cancer, there
is not a strong correlation/overlap between the different markers
used, and also none of them has been shown a valid prognostic
factor, not correlating statistically with DFS and OS.
The only marker statistically related to the prognostic index of
cell proliferation, Ki67, was CD338 (p value = 0.046).
These data make us conclude that the panels of CSCs markers
currently used for the detection of cancer stem cells in Triple
Negative breast cancer are inadequate and do not represent the
useful prognostic markers for this neoplasia.
Evidence of loss of heterozygosity of an intron
1 polymorphic sequence of epidermal growth
factor receptor in normal epithelium surrounding
basal like breast cancer
V. Dimartino, E. Melucci, S. Conti, V. D’Alicandro, A. Di
Benedetto, C.A. Amoreo, E. Pescarmona, A. Fabi, C. Nisticò,
C. Ercolani, B. Antoniani, L. Perracchio, C. Botti, M. Mottolese
Regina Elena National Cancer Institute Rome, Italy
Background. Breast cancer (BC) is currently regarded as a heterogeneous
disease classified, through gene expression analysis,
into various molecular subtypes with different biological characteristics
and clinical behaviour. Within the Triple Negative (TN)
subtype, defined as a BC with hormonal receptors and HER2
negative, the expression of the basal cytokeratin (CK5) and
EGFR may identify a subgroup of very aggressive tumor, called
basal-like, encompassing about 10% of BC that display a poor
prognosis 1 . Recently, in vitro and in vivo studies reported that
the length of a CA Simple Sequence Repeat 1 (CASSRI) dinucleotides
in the intron 1 of egfr was associated with the expression of
the protein. In addition, the loss of heterozigosity (LOH) within
this region would also lead to altered receptor expression 2 3 .
In this study we aimed to determine the association between LOH
and overexpression of EGFR in a series of basal-like BC and their
autologous uninvolved peritumoral tissues (PTT) in comparison
to normal tissues (NT).
395
Material and methods. 41 TN BC, the correspondent PTT
and the autologous NT were analyzed for EGFR, CK5 expression
by immunohistochemistry (IHC) and for LOH using
a capillary electrophoresis. The assessment of LOH on
the 3 tissue substrates were evaluated comparing the peak
area of the two alleles using the following equation: LOH
score = T1XN2/T2XN1, where T is BC or PTT, N is normal
tissue, 1 is the area under the peak the shorter allele, and 2 to
the longer allele. The result was significantly different when
the LOH score was < 0.79 (loss of the longer allele) or > 1.27
(loss of the shorter allele).
Results. Of the 41 TN BC, 35 (85%) were basal-like BC (EGFR+
and/or CK5+) and were included in the study. Of the 20 EGFR
positive basal-like BC, 14 (70%) showed LOH whereas of the
15 EGFR negative/ CK5 + basal-like BC, only 5 (33%) showed
LOH (p = 0.03) (Tab. I).
In 9 out of 14 basal-like BC displaying LOH (64%), the PTT
presented a genetic profile similar to NT and did not show
LOH. Interestingly, in 5 EGFR positive BC (36%) the PTT
was different from NT, presented LOH and was EGFR positive
(Fig. 1).
Tab. I. Correlation between EGfR protein expression and lOH in 35
basal-like BC.
LOH NEG LOH POS TOTAL OF CASES
EGfR NEG 10 (66%) 5 (33%) 15
EGfR pOS 6 (30%) 14 (70%) 20
tOtal Of CaSES 16 19 35
p = 0.03
Fig. 1. lOH distribution in ptt of 14 basal-like BC with lOH of CaSSRi
in the intron 1 of egfr.
Conclusions. Our data indicate that LOH of CASSRI in the
intron 1 of egfr is related to EGFR expression in basal-like BC.
In addition, the evidence of LOH in PTT, denoting the occurrence
of early molecular alterations in morphologically NT,
could represent a potential biomarker with diagnostic/prognostic
implications.
references
1 Reis-Filho JS, Tutt ANJ. Triple negative tumours: a critical review.
Histopathology 2008;52:108-18.
2 Buerger H, Gebhardt F, Schmidt H, et al. Length and loss of heterozygosity
of an intron 1 polymorphic sequence of egfr is related to cytogenetic
alterations and epithelial growth factor receptor expression.
Cancer Res 2000.
3 Brandt B, Meyer-Staeckling S, Schmidt H, et al. Mechanisms of egfr
gene transcription modulation: relationship to cancer risk and therapy
response. Clin Cancer Res 2006.