Journal of Cancer Therapy, 2013, 4, 21-31 Published Online August 2013 (
Grade Dependent Expression of Growth Factor Receptors
and Signaling Molecules in Breast Cancer*
Chellakkan Selvanesan Benson1, Somasundaram Dinesh Babu1, Selvi Radhakrishna2,
Nagarajan Selvamurugan3, Bhaskaran Ravi Sankar1#
1Department of Endocrinology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Cam-
pus, Chennai, India; 2Chennai Breast Centre, Chennai, India; 3Department of Biotechnology, School of Bioengineering, SRM Uni-
versity, Kattankulathur, India.
Received May 16th, 2013; revised June 18th, 2013; accepted June 25th, 2013
Copyright © 2013 Chellakkan Selvanesan Benson et al. This is an open access article distributed under the Creative Commons At-
tribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is prop-
erly cited.
Growth factor signaling plays a key role in the growth and development of breast. Aberrant expression and activation of
growth factors like insulin like growth factor-I (IGF-I) and epidermal growth factor (EGF) and their downstream sig-
naling has been implicated in breast cancer. The deregulation of growth factor signaling is associated with increased
proliferation and cell survival, decreased apoptosis, invasion, angiogenesis and metastasis. The aim of the present study
is to survey the different signaling molecules involved in the IGF and EGF signaling pathways, and to find if there are
any relationship between breast cancer and their levels and activation. Thirty-nine samples of breast cancer tissues (24
Grade II and 15 Grade III tumours) and sixteen normal breast tissue samples were collected. The expression of the re-
ceptors and signaling molecules were investigated using Western blot. IGF-IRβ, AR, pAkt, IKK-α and p38 are upregu-
lated in cancer tissues in a grade depended manner. Further, Akt and β-catenin were also upregulated in cancer samples.
Correlation analysis of signaling molecules revealed a disruption in their expression in cancer tissues. The present study
shows that various signaling molecules are upregulated or activated in cancer tissues involving IGF-IR and Akt path-
way. The expression of signaling molecules in the cancer tissues were deregulated when compared to the control sam-
ples. Thus, flawed expression and over activation of Akt pathway is seen in the breast cancer tissues.
Keywords: Breast Cancer; Growth Factors; IGF-IR; EGF-R; Cancer Grade; Steroid Receptor
1. Introduction
Breast cancer is a worldwide health concern for women.
Growth factors stimulate cellular growth, proliferation
and differentiation and are vital for the normal develop-
ment and function of the breast [1]. In breast cancer, in-
sulin-like growth factor (IGF) and epidermal growth
factor (EGF) signaling systems are affected leading to
abnormal mitogenicity and cell survival. Further, estro-
gen act synergistically with growth factors to enhance the
mitogenic effect of growth factors by inducing expres-
sion of several members of the IGF and EGF family [2].
IGF signaling system plays a critical role in the growth
and development of many tissues. However, IGF system
is also implicated in various pathophysiological condi-
tions and is thought to play a prominent role in tumori-
genesis [3]. High serum IGF-I levels predict an increased
risk of breast cancer [4]. Both experimental and clinical
studies have demonstrated that IGF-IR is overexpressed
in cancer cells compared with normal tissues [5]. EGF
receptor (EGFR) has been considered a nodal point
which converges many cytokine and hormone-induced
signals to lead to MAPK activation [6]. EGFR signaling
can induce epithelial to mesenchymal transition, invasion,
and metastasis in different cancer cell types, including
human breast cancer cells [7].
Downstream signaling of growth factors involves Akt
and ERK pathways which consist of an array of signaling
molecules. Akt signaling pathway regulates diverse bio-
logical functions, including cellular proliferation, sur-
vival, and motility in cancer cells. Glycogen synthase
*The work was supported by Department of Science and Technology,
INSPIRE, IF 10052.
#Corresponding author.
Copyright © 2013 SciRes. JCT
Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
kinase 3β (GSK-3β), a downstream molecule of Akt, is a
key target of PI 3-kinase signaling leading to prevention
of apoptosis [8]. β-catenin was a poor prognostic marker
in human cancer and was implicated in human breast
cancer. There is a strong correlation between β-catenin
activity and cyclin D1 expression in both breast cancer
cell lines and breast patient tissue samples and it also
known to activate MMP-7 during cancer [9]. ERK is
largely activated by growth factor signals [10]. Elevated
MAPK activation was found in breast carcinoma com-
pared with benign breast tissue [11]. The p38 MAPKs
have also been shown to play roles in cell proliferation
and survival. p38 MAPK also plays a role in the down-
stream signaling of VEGF leading to angiogenesis [12].
NF-κB has also been shown to be involved in the devel-
opment of carcinomas, cancers of epithelial origin, such
as breast cancer. The activation of NF-κB is controlled
by IKK-α and IKK-β, by canonical pathway, NF-κB
plays a major role in inflammation, cell survival, trans-
formation, and oncogenesis in breast cancer [13].
Breast cells are also under steroid hormone regulation
with estrogen and progesterone controlling the rate of
mitosis [14]. Estrogen receptors (ERs) belong to the
ligand regulated transcription factors that transduce hor-
mone signals into a large variety of physiological re-
sponses in various organs including breast. Both the ge-
nomic and non-genomic actions of estrogen play pivotal
roles in E2-induced cancer cell proliferation and survival
[15]. The role of the androgen receptor (AR) in breast
carcinomas has drawn great attention in recent years,
especially due to its expression in ER and PR negative
breast carcinomas [16]. Epidemiologic studies showed
that increased serum androgen level was associated with
an increased risk for breast cancer in postmenopausal
patients [17]. Hanley et al. investigated the potential role
of AR in relation to breast tumor progression and showed
that 93% of 43 high-grade ductal carcinoma in situ cases
expressed AR, whereas only 55% of 44 high grade inva-
sive ductal carcinomas showed AR expression showing a
grade dependent upregulation [18].
Thus several growth factor pathways and steroid re-
ceptors play various roles in cancer progression. Our
objective for this study was is to survey the protein levels
of the signaling molecules involved in the IGF and EGF
signaling pathways along with ER and AR, and to find if
there are any relationship between the breast cancer and
the levels and activation of key signaling molecules.
2. Materials and Methods
2.1. Tissue Samples
The study was performed with approval of the Ethics
Committee of the University of Madras, India, (Ref No:
PGIBMS/CO/Human Ethical/2009-10/353) and was car-
ried out in accordance with the Helsinki declaration of
2000 of the World Medical Association. Breast tumor
removal surgeries were performed by a trained breast
cancer surgeon (S.R) at Chennai Breast Centre, Chennai,
India. Thirty-nine samples of breast cancer tissue (24
Grade II and 15 Grade III tumours) and sixteen normal
breast tissue samples were obtained. Normal breast tis-
sues were obtained from outside the tumor margin and
these tissues were analysed histologically to exclude
them from any forms of malignancy or other pathological
findings (Data not shown).
2.2. Western Blotting
For protein extraction, 50 mg of tissue samples were
lysed in pre-cooled RIPA-buffer containing phosphatase
inhibitors (Pierce Biotechnology Inc, USA), proteinase
inhibitors (Roche, Germany). Equal amount of total pro-
tein (35 μg) was mixed with 2X sample buffer and boiled
for 5 min. The protein was separated on 10% SDS-PAGE
and electrotransfered onto a PVDF membrane (Bio-Rad,
USA). To avoid non-specific binding, membranes were
blocked with 5% non-fat milk protein in PBS/Tween at
RT for 3 hours. After blocking, membranes were incu-
bated with respective rabbit polyclonal antibodies (Cell
signaling Technologies, USA) pAkt (#9271S), Akt
(#4685), pERk (#1972), Erk (#9102), pGSK (#9336),
GSK (#9315), IKK-α (#2682), IKK-β (#2684), β-catanin
(#9562), p38 (#9212), IGF-IRβ (#3027), EGRF (#4267),
ERα (sc-543), and AR (sc-815), in 1:2000 dilution for
overnight at 4˚C. For mouse monoclonal β-actin antibody
in 1:5000 dilutions. Finally, signals were visualized using
Enhanced Chemiluminescent System (Pierce Biotechno-
logy Inc., USA) and the signals were captured by Chemi
Doc XRS system (Bio Rad, USA) and the intensity of the
bands were quantified by Quantity One software (Bio
Rad, USA).
2.3. Data Analysis and Statistics
Protein expression data from normal (control) and cancer
tissues were analysed by Kruskal-Wallis test followed by
Mann-Whitney test. Protein expression data was further
subjected to Pearson correlation analysis to identify the
correlations between the signaling molecules within the
control and within the cancer samples respectively. Cor-
relation analysis for cancer samples were performed by
pooling data from Grade II and Grade III. To analyse if
there are any differences in the correlation coefficients
between control and cancer tissues Fisher transformation
analysis was performed for correlation coefficients with r >
0.8. SPSS 17.0 software package was used for data ana-
lysis and Graph Pad prism 5.0 software was used to draw
graphs. Fisher transformation analysis was done using
Copyright © 2013 SciRes. JCT
Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer 23
MedCalc software. Data was considered statistically sig-
nificant when p < 0.05.
3. Results
3.1. Patients Data
In the present study, we analysed 24 Grade II samples
and 15 Grade III samples from patients of age range from
29 to 85 with a mean age of 56 years. The patient data is
summarized in Table 1. The patients with Grade II tu-
mour had bigger tumour size and the nodal status had no
difference between the groups. More patients in Grade III
tumour had lymph node metastasis at the time of diagno-
sis. The distribution of the estrogen receptor (ER), pro-
gesterone receptor (PR) and human epidermal growth
factor receptor 2 (HER2) statuses is shown in Figures
1(a) and (b). The ER, PR and HER2 status was done by
3.2. IGF-IRβ and EGF-R Levels in Control and
Breast Cancer Samples
IGF-IRβ is highly expressed in cancer and its protein
level increased in Grade II (p < 0.001) and Grade III (p
< 0.0001) when compared to control. There was no dif-
ference in the IGF-IRβ levels between Grade II and
Grade III cancer samples (Figures 2 and 3(a)). Our data
also show that IGF-IRβ levels where upregulated in
87.2% of the cancer samples (Table 2). EGF-R protein
levels are upregulated in cancer grade III (p < 0.003)
when compared to Grade II but did not show any dif-
ference when compared to the controls (Figures 2
Table 1. G2: moderately differentiated tumor; G3: poorly
differentiated; T: tumor grade; N: nodal status; L: inva-
sion of lymphatic vessels.
Age Grade II Grade III
T (Tumor Size)
N (Nodal Status)
Not Known
L (Invasion of Lymphatic Vessel)
Not Known
and 3(b)). However, it is interesting to note that 59%
of the cancer patients had elevated levels of EGF-R
when compared to the controls (Table 2) and 80% of
Grade III patients have elevated levels of EGF-R (Ta-
ble 2).
3.3. Expression of Signaling Molecules
Downstream to IGF and EGF
The Akt protein level increased in Grade II (p < 0.003)
when compared with control whereas pAkt levels
showed increase in Grade III (p < 0.001) when compared
to the control and showed a grade dependent increasing
tendency (Figures 2, 3(c) and (d)). Akt and pAkt levels
were more than the control levels in 71.8% and 69.2 % of
the cancer patients respectively (Table 2). Neither ERK
nor its phosphorylation levels show any difference be-
tween the control and the cancer tissue (Figures 2, 3(e)
and (f)). Similar observations were seen in the levels of
Table 2. Percentage of up and down regulation of signaling
molecules and receptors in cancer samples when compared
with control.
Signaling MoleculesGrade II Grade III Grade II and
Grade III
16.7% 6.7% 12.8%
IGF-R 83.3% 93.3% 87.2%
54.2% 20.0% 41.0%
EGF-R 45.8% 80.0% 59.0%
41.7% 13.3% 30.8%
pAkt 58.3 % 86.7% 69.2%
20.8% 40% 28.2%
Akt 79.2% 60% 71.8%
65% 71.4% 67.6%
pERK 35% 28.6% 32.4 %
29.2% 33.3% 30.8%
ERK 70.8% 66.7% 69.2%
83.3% 46.7% 69.2%
pGSK 16.7% 53.3% 30.8%
79.2% 60% 71.8%
GSK 20.8% 40% 28.2%
16.7% 6.7% 12.8%
IKK-α 83.3% 93.3% 87.2%
62.5% 46.7% 56.4%
IKK-β 37.5% 53.3% 43.6%
25% 13.3% 20.5%
p38 75% 86.7% 79.5%
16.7% 13.3% 15.4%
β-catenin 83.3 % 86.7% 84.6%
20.8% 6.7% 15.4%
ERα 79.2% 93.3% 84.6%
25% 0% 15.4%
AR 75% 100% 84.6%
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Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
Copyright © 2013 SciRes. JCT
Figure 1. Venn diagram shows the presence of ER, PR and HER2 and their distribution among the samples in Grade II (Fig-
ure 1(a)) and Grade II (Figure 1(b)) breast cancer tissues.
Figure 2. Protein lysates were isolated from normal breast (Control), breast cancer tissue Grade II (G2) and breast cancer
tissue Grade II (G3). Protein samples were separated by polycrylamide gel electropgoresis and expression of proteins was
visualized using specific antibodies. β-actin was used as internal loading control.
GSK and pGSK (Figures 2, 3(g) and (h)). IKK-α levels
increased in cancer Grade II (p < 0.01) and Grade III (p <
0.001) when compared to controls showing a grade de-
pendent increase with 87.2% (Table 2) of samples in
cancer patients showing upregulation (Figures 2 and
3(i)). However, IKK-β did not display any changes (Fig-
ures 2 and 3(g), (j)). The levels of p38 protein was
higher in Grade II (p < 0.013) and in Grade III (p < 0.001)
when compared with control (Figures 2 and 3(k)) with
79.5% of the cancer samples showing upregulation (Ta-
ble 2). β-catenin also showed similar pattern with
higher protein levels in Grade II (p < 0.031) and Grade
III (p < 0.053) when compared to controls (Figures 2
and 3(l)). Further, 84.6% of the cancer samples dis-
played upregulation when compared to the control
samples (Table 2).
3.4. ERα and AR in Different Stages of Breast
The ERα expression did not show any difference be-
tween control and cancer tissues but showed an upregu-
lating tendency (Figures 2 and 4(a)). In 84.6% of the
samples ERα expression was higher than the control
samples (Table 2). AR expression progressively increas-
ed in Grade II (p < 0.002) and in Grade III (p < 0.0001)
when compared with control (Figures 2 and 4(b)). It is
interesting to note that AR levels were upregulated
84.6% of cancer samples when compared to the controls
(Table 2).
3.5. Correlation between Signaling Molecules in
Control and Cancer Tissues
Pearson correlation analysis was performed to find in-
ter-relationship of the signaling molecules/receptors in
control samples and to identify if this relationship is
altered in cancer tissues. Results clearly indicate that
correlation exists between the levels of various sig-
naling molecules in the control samples (Table 3).
There is a strong positive (r > 0.8) correlation between
the levels of pERK and IKK-β (p < 0.001, r =
Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer 25
Figure 3. Dot plot analysis of densitometrically quantified expression of IGF-IRβ(a), EGF-R(b), pAk, Akt(d), pERK(e),
ERK(f), pGSK3β(g), GSK3β(h), IKK-α(i), IKK-α(j), β-catenin(k), p38(l). Protein levels were normalized to the corresponding
expression of β-actin. For each protein three dotplots are mapped, Control, Grade II and Grade III. The line within the dot
plot corresponds to the median value, and ba rs indicate the smallest and largest observations. Comparison of expression val-
ues between the groups was performed by Kruskal-Wallis test followed by Mann-Whitney test. p values <0.05 were consid-
ered as statistically significant.
Copyright © 2013 SciRes. JCT
Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
Figure 4. Dot plot analysis of densitometrically quantified expression of AR and ER-α. Protein levels were normalized to the
corresponding expression of β-actin. For each protein three dot plots are mapped, Control, Grade II and Grade III. The line
within the dot plot corresponds to the median value, and bars indicate the smallest and largest observations. Comparison of
expression values between the groups was performed by Kruskal-Wallis test followed by Mann-Whitney test. p values <0.05
were considered as statistically significant.
0.824), pGSK and β-catenin (p < 0.001, r = 0.802),
pGSK and ERα (p < 0.001, r = 0.825), pGSK and IGF-R
(p < 0.001, r = 0.849), pGSK and EGF-R (p < 0.001, r =
0.855), GSK and p38 (p < 0.001, r = 0.839), IKK-α and
β-catenin (p < 0.001, r = 0.901), IKK-α and ERα (p <
0.001, r = 0.893), IKK-α and EGF-R (p < 0.001, r =
0.885), β-catenin and ERα (p < 0.001, r = 0.896),
β-catenin and IGF-R (p < 0.001, r = 0.830), β-catenin
and EGF-R (p < 0.001, r = 0.978), ERα and IGF-R (p <
0.001, r = 0.846), ERα and IGF-R (p < 0.001, r = 0.898)
and IGF-R and EGF-R (p < 0.001, r = 0.828) in the
cancer free control tissue. Interestingly, a new correla-
tion emerged between IKK-α and IKK-β (p < 0.001, r =
0.850), (Table 4). Further, comparison of correspond-
ing correlation coefficients between control and cancer
samples reveal that almost all except the correlations
seen between IKKα vs. ERα, and β-catenin vs. IGF-IR
in the control samples are lost in the cancer tissues
(Table 5).
4. Discussion
Growth factor signaling plays a vital role in the cancer
progression cellular proliferation and metastasis. Sub-
stantial evidences implicate IGF signaling in the devel-
opment and progression of many cancers, including
breast cancer [19] and upregulation of IGF-I is often as-
sociated with poor prognosis [4]. The present study
shows a grade dependent upregulation of IGF-IR in can-
cer tissues. Similar IGF-IR upregulation in cancer tissues
were previously reported in Canadian population. Further,
correlation analysis within the control and cancer sam-
ples show that in normal breast tissues IGF-IR has a
positive correlation with GSK, β-catenin and ERα, but
the correlation between IGF-IR and GSK, and IGF-IR
and ERα was lost in cancer tissues indicating a perturbed
expression of signaling molecules in cancer cells.
Over expression of EGF-R in breast cancer is associ-
ated with large tumor size, poor differentiation and poor
clinical outcomes. Further, EGF-R over expression has
been associated with higher grade and extensive forms of
ductal carcinoma in situ [20]. Although in the present
study EGF-R did not increase in cancer tissues, it is im-
portant to note that its levels were upregulated in 80% of
the Grade III patients. Similar upregulation of EGF-R
inhigher grade cancer was has been reported [20]. Cor-
relation analysis shows that in control samples EGF-R is
positively correlated with pGSK, IKK-α, β-catenin, ERα
and IGF-R, but in cancer tissues EGF-R lost all these
correlations suggesting abnormal expression of these
molecules which could lead to flawed signaling.
Our study also shows that the expressions of various
downstream signaling molecules to the growth factor
receptors are affected in cancer tissues. Akt pathway is
an important regulator of cell proliferation and survival
and is deregulated in breast cancer. In the present study
pAkt shows a grade depended increase in cancer, sug-
gesting hyper-activation of Akt molecules in cancer tis-
sues. However, ERK expression and its phosphorylation
did not show any increase in cancer tissues and pERK
was lower in 67.6% cancer samples when compared to
controls. Thus our data shows an apparent domination of
Akt pathway over ERK pathway in cancer tissues. West-
ern blot data shows that downstream signaling molecules
of Akt are upregulated in cancer samples. IKK-α is a
regulatory molecule of NF-κB, pAkt activates the IKK-α
by phosphorylating it, and thereby activating the NF-κB
[21]. Our data shows that there is an upregulation in the
overall IKK-α expression and is increased in 87.2% of
the cancer samples indicating an Akt induced IKK-α ac-
tivation. Activated IKK-α could promote NF-κB medi-
ated transcription [22]. GSK, a downstream signaling
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Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
Copyright © 2013 SciRes. JCT
Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
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Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
Copyright © 2013 SciRes. JCT
Table 5. Comparison of correlation co-efficients within control and breast cancer tissues (Fisher transformation analysis).
S No Group r = Values Correlation co-efficient
Control pERK vs IKKβ r = 0.824
1 Cancer pERK vs IKKβ r = 0.430
p = 0.028*
z = 2.1919
Control GSK vs p38 r = 0.839
2 Cancer GSK vs p38 r = 0.119
p = 0.0007*
z = 3.3940
Control pGSK vs β-catenin r = 0.802
3 Cancer pGSK vs β-catenin r = 0.293
p = 0.0132*
z = 2.4797
Control IKK-α vs β-catenin r = 0.901
4 Cancer IKK-α vs β-catenin r = 0.005
p = 0.0001*
z = 4.5508
Control pGSK vs ER-α r = 0.825
5 Cancer pGSK vs ER-α r = 0.004
p = 0.0003*
z = 3.6105
Control IKK-α vs ER-α r = 0.893
6 Cancer IKK-α vs ER-α r = 0.777
p = 0.2037
z = 1.2711
Control β-catenin vs ER-α r = 0.896
7 Cancer β-catenin vs ER-α r = 0.011
p 0.001*
z = 4.4520
Control pGSK vs IGF-IR r = 0.849
8 Cancer pGSK vs IGF-IR r = 0.279
p = 0.0028*
z = 2.9853
Control β-catenin vs IGF-IR r = 0.830
9 Cancer β-catenin vs IGF-IR r = 0.660
p = 0.2218
z = 1.2217
Control ER-α vs IGF-IR r = 0.846
10 Cancer ER-α vs IGF-IR r = 0.008
p = 0.001*
z = 3.8134
Control pGSK vs EGF-R r = 0.855
11 Cancer pGSK vs EGF-R r = 0.625
p = 0.0944*
z = 1.6728
Control IKK-α vs EGF-R r = 0.885
12 Cancer IKK-α vs EGF-R r = 0.356
p = 0.0015*
z = 3.1711
Control β-catenin vs EGF-R r = 0.978
13 Cancer β-catenin vs EGF-R r = 0.524
p 0.0001*
z = 5.1536
Control ER-α vs EGF-R r = 0.898
14 Cancer ER-α vs EGF-R r = 0.177
p = 0.0001*
z = 3.964
Control IGF-IR vs EGF-R r = 0.850
15 Cancer IGF-IR vs EGF-R r = 0.153
p = 0.0426*
z = 2.027
Breast Cancer
Cancer IKK-α vs IKK-β r = 0.850
1 Control IKK-α vs IKK-β r = 0.153
p = 0.0007*
z = 3.4055
r: Pearson correlation; p: Significance; z: Correlation co-efficient; *Significant values.
molecule of Akt did not show any change in its expres-
sion or phosphorylation. GSK is deactivated by phos-
phorylation [23]. The absence of increase in pGSK sug-
gests that GSK is active even though its levels did not
change. However, β-catenin which is downstream to
GSK is highly expressed in cancer samples. β-catenin
increases proliferation in ER positive breast cancer cells
by activating cyclin D1 ([9]. A previous study shows that
higher expression of β-catenin along with p53 is corre-
lated with worse survival [24]. Thus, signaling molecules
downstream to Akt are highly expressed and activated in
breast cancer tissues indicating abnormal activation of
this pathway.
The role of p38 MAP kinase in cancer has been thought
to occur through negative regulation of the cell cycle and
senescence, suggesting that p38 MAPK is a tumor sup-
pressor gene [25]. However, a recent study in MCF-7
breast cancer cell line shows that EGF-R phosphorylation
leads to the activation of p38 mediated cell survival [26].
Previous study suggests that p38 activity was found to be
upregulated in various carcinomas including that of the
breast [27]. In the present study p38 is highly expressed
in cancer tissue when compared with control indicating
its role in breast cancer.
ER is often overexpressed in majority of in breast
cancer along with IGF-IR. In this study, although ERα
Grade Dependent Expression of Growth Factor Receptors and Signaling Molecules in Breast Cancer
levels were not significantly upregulated, it was elevated
in 84.6% of the samples when compared with normal
tissues. Previous study shows that ERα binds in an es-
trogen depended manner to the p85α subunit of the PI3K,
leading to the activation of Akt [28]. It is likely that in
the ER positive patients Akt is activated via ERα but
additional evidences are needed to confirm this possibil-
ity. Interestingly, AR was upregulated in a grade de-
pendent manner with 75% of grade II and all of grade III
samples showing upregulation.
AR upregulation has been shown in several earlier stu-
dies [18]. The upregulated AR expression may activate
the p21 [29], which is a positive regulator of cell cycle.
Previous study also suggests that p21 overexpression is
associated with tumor metastasis in canine mammary
tumours [30]. By this mechanism AR can insert the no
genomic action through this pathway.
5. Conclusion
In conclusion, the present study shows that several sig-
naling molecules are upregulated/activated in cancer tis-
sues in a grade depended manner, and the pathway in-
volving IGF-IR and Akt seems to be actively involved in
breast cancer tissues. Signaling pathways important for
cell survival involving Akt are highly activated in cancer
samples. Further, there is a deregulation in the expression
of signaling molecules in the cancer tissues when com-
pared to the control samples.
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