Sonic Hedgehog Signaling is Active in Human Adrenal Cortex Development and Deregulated in Adrenocortical Tumors
Débora C. Gomes1, Letícia F. Leal1, Livia M. Mermejo1, Carlos A. Scrideli1, Carlos E. Martinelli Jr.1, Maria C. B. V. Fragoso2, Ana C. Latronico2, Luis G. Tone1, Silvio Tucci1, Jose A. Yunes3, Izilda A. Cardinalli3, Maria J. Mastellaro3, Silvia R. Brandalise3, Fernando Ramalho1, Ayrton C. Moreira1, Leandra N. Ramalho1, Margaret de Castro1, Sonir R. R. Antonini1
School of Medicine of Ribeirao Preto -University of Sao Paulo, Brazil1, School of Medicine - University of Sao Paulo2, Boldrini Children’s Center3
Background: The sonic hedgehog (SHH) pathway plays a key role in rodent adrenal cortex devel- opment and is involved in tumorigenesis in several human tissues, but data in human adrenal glands are limited.
Objectives: To analyze the involvement of the SHH pathway in human adrenal development and tumorigenesis and the effects of SHH inhibition on an adrenocortical tumor (ACT) cell line.
Patients & Methods: Expression of SHH pathway components was evaluated by immunohisto- chemistry (IHC) in 51 normal adrenals (33 fetal) and 34 ACTs (23 pediatric), and by qPCR in 81 ACTs (61 pediatric) and 19 controls (10 pediatric). The effects of SHH pathway inhibition on gene ex- pression and cell viability in the NCI-H295A adrenocortical tumor cell line after cyclopamine treat- ment were analyzed.
Results: SHH pathway proteins were present in fetal and postnatal normal adrenals and showed distinct patterns of spatiotemporal expression throughout development. Adult ACCs presented with higher expression of PTCH1, SMO, GLI3 and SUFU compared with normal adult adrenal cor- tices. Conversely, pediatric ACTs showed lower mRNA expression of SHH, PTCH1, SMO, GLI1 and GLI3 compared with normal pediatric adrenal cortices. In vitro treatment with cyclopamine re- sulted in decreased GLI3, SFRP1, CTNNB1 mRNA expression and beta-catenin staining, as well as decreased cell viability.
Conclusions: The SHH pathway is active in human fetal and postnatal adrenals, up regulated in adult ACCs and down regulated in pediatric ACTs. SHH pathway antagonism impaired cell viability. The SHH pathway is deregulated in ACTs and might provide a new target therapy to be explored.
B enign adrenocortical tumors (ACTs) are relatively fre- quent in adults, whereas adrenocortical carcinomas (ACCs) are rare and exhibit very aggressive behavior (1). Increased incidence of ACTs in children has been observed in the South and Southeastern regions of Brazil, often in association with the germline p.R337H P53 mutation (2, 3). Recent data have shown that only 3% of children car-
rying this mutation develop ACTs (4). Therefore, it is likely that additional genetic events contribute in adreno- cortical tumor development. Studies on the molecular ba- sis of ACTs have demonstrated that genes and pathways involved in normal adrenal cortex development and main- tenance are important in tumorigenesis (5). Outstanding among these factors are activation of the Wnt/B-catenin
Abbreviations:
Copyright @ 2014 by the Endocrine Society
Received November 14, 2013. Accepted March 28, 2014.
doi: 10.1210/jc.2013-4098
THE JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM
JCEM
EARLY RELEASE:
ENDOCRINE
SOCIETY
pathway and IGF2 overexpression (3, 6-8). However, the knowledge that has, until now, been accumulated is in- sufficient to account for the events required for tumor initiation and malignant transformation (9, 10).
The hedgehog (Hh) pathway is important in cell growth and differentiation, embryonic development, adult tissue homeostasis and tumorigenesis, and plays a role in mam- malian adrenal cortex development (11-14). In verte- brates, Hh activation is triggered by Hh ligand binding to a receptor complex formed by the transmembrane protein patched 1 (PTCH1) and a coreceptor (cell adhesion asso- ciated, oncogene regulated - CDO, BOC cell adhesion associated, oncogene regulated - BOC or growth arrest- specific1 - GAS1). In the presence of the ligand, the smoothened, frizzled class receptor (SMO) is released from PTCH1 inhibition and activates the transcription factors GLI1, GLI2 and GLI3. In the absence of the ligand, GLI2 and GLI3 are targeted to proteasomal processing into repressor forms, which act as transcriptional repres- sors (15).
In mice and rat adrenals, Sonic hedgehog (SHH) is the main ligand of the Hh pathway (16). Shh is mainly ex- pressed underneath the adrenal capsule and Gli1 is ex- pressed in the capsule (12-14, 17). Conditional Shh inac- tivation in the adrenal cortex produces adrenal cortex and capsule hypoplasia (12, 13). Moreover, Gli1-positive cells migrate centripetally, supporting the role of this pathway in adrenocortical growth (13, 14). On the other hand, studies on the role of SHH signaling in human adrenal physiology are limited. Nevertheless, the discovery of ad- renal hypoplasia in some patients with Pallister-Hall Syn- drome, which is caused by GLI3 mutations, suggests its importance (18). Moreover, abnormalities in the SHH pathway have been linked to several cancers, such as basal cell carcinoma, medulloblastoma, glioblastoma, and rhabdomyosarcoma (19). Based on these data, we hypoth- esized that SHH pathway abnormalities may be important in adrenocortical tumorigenesis.
In the present study, we show that key proteins of the SHH pathway present distinct patterns of expression de- pending on the developmental stage in the normal human adrenal cortex. Moreover, we observed differential ex- pression of SHH pathway genes in pediatric and adult ACTs. In addition, we demonstrated that SHH signaling inhibition results in cell viability impairment in NCI- H295A adrenocortical tumor cell line.
SUBEJCTS AND METHODS
Normal fetal and postnatal adrenal panel
A retrospective study was carried out in a group of 51 normal adrenal tissues obtained from spontaneously miscarried fetuses
or from children who underwent routine autopsy examination in the Department of Pathology, School of Medicine of Ribeirao Preto. Tissues specimens were analyzed according to gestational or postnatal age: 20 to 25 weeks (n = 14), 26 to 31 weeks (n = 10), 32 to 37 weeks (n = 9), and neonates to 10-year-old children (n = 18). Fetuses or children with multiple malformations or children with previous use of glucocorticoids were excluded. This section of the study was approved by the local Ethics Com- mittee (protocol 2011/11614).
Immunohistochemical (IHC) analyses- Normal Adrenals
Routine hematoxylin-eosin staining was performed to eval- uate adrenal morphology. IHC studies were performed using the primary antibodies anti-SHH (sc-1194), anti-GLI1 (sc-20687), anti-GLI2 (Ab-7181), and anti-GLI3 (sc-20688), as has previ- ously been validated (20, 21). Labeling was developed with DAB (Vector Laboratories Inc.) and the sections were counterstained with Harris hematoxylin.These samples were analyzed by D.C.G. and S.R.A and confirmed by an experienced pathologist (L.Z.R.). A descriptive analysis in each developmental stage is presented. Detailed methodology is shown in the Supplemental Data.
Adrenocortical tumors
Patients
Eighty-one patients with ACTs diagnosed between 1991 and 2012 at three reference centers in southeastern Brazil were en- rolled in this study. Routine diagnostic tests and imaging eval- uations were performed before surgical treatment and the pa- tients were followed up after surgery, as previously reported (3). Disease stages were classified according to the classifications of Sandrini and Macfarlane, modified by Sullivan for children and adults, respectively (22, 23). In addition, ACTs with available tissues were classified according to the Weiss score (24). Adult ACTs were classified as adenoma (ACA) or carcinoma (ACC), according to Weiss < 3 or ≥ 3, respectively. In the pediatric group, we did not categorize ACTs as ACA or ACT according to the Weiss score, because this criterion is not entirely applicable and does not accurately predict clinical outcomes (24). Nineteen normal adrenal cortices were analyzed as controls: 10 pediatric specimens were obtained after surgical treatment of Wilms’ tu- mor and 9 from adult subjects with sudden deaths who under- went routine autopsy. This study was approved by the Ethics Committees (protocols 2011/5721 and 0005.0.144.000-10). Informed written consent was obtained from patients and con- trols or their parents.
Quantitative real time PCR (qPCR)
The mRNA expression was analyzed with qPCR as previ- ously described (3) using specific Taqman assays (Applied Bio- systems): SHH (Hs00179843 m1), PTCH1 (Hs00181117 m1), SMO (Hs01090242 m1), GLI1 (Hs01110766 m1), GLI2 (Hs01119974 m1), GLI3 (Hs00609233 m1), and SUFU (suppressor of fused; Hs00171981 m1). GUSB (beta glucuronidase; 4326320E) was used as the endogenous control. Normal pediatric and adult ad- renal cortices were used as controls for pediatric and adult ACTs, respectively. Relative mRNA expression values were determined by the 2-44Ct method.
IHC analyses- ACTs
IHC for SHH, GLI1 and GLI3 proteins was performed as described above in a subset of 34 tumors (23 pediatric, 11 adults) depending on the availability of paraffin-embedded samples. Each marker was evaluated randomly in at least 10 representa- tive high-power fields (x400). According to staining, each sample was defined as negative (less than 1%), +1 (weak, 1%-10%), +2 (moderate, 11%-50%) and +3 (strong, more than 50%). The normal adrenal cortex tissues present in the sample were considered as the control.
In Vitro Study
NCI-H295A adrenocortical cell line
NCI-H295A adrenocortical tumor cells, a lineage established from an adult adrenocortical carcinoma harboring a CTNNB1 mutation (25), were cultured in RPMI 1640 (GIBCO, Life Tech- nologies, Foster City, CA), supplemented with 2% fetal bovine serum, 1% ITS Premix (BD Biosciences) and 1% penicillin/strep- tomycin (100 mg/ml; GIBCO), and maintained at 37°℃ with 5% CO2.
SHH pathway inhibition (Cyclopamine)
Cells were plated in 24-well plates at a density of 200 x 103cells/well. After 24 hours, the medium was replaced and cells were treated with 5 or 20 uM cyclopamine (Sigma-Aldrich, St. Louis, MO), an SMO inhibitor. Dimethylsulfoxide (DMSO- Sig- ma-Aldrich, St. Louis, MO) 0.1% was used as a control. After 24 hours incubation, medium was removed and 250 µL TRIzol was added to each well for RNA extraction. Expression of GLI1, GLI3, SFRP1 (secreted frizzled-related protein 1; Hs00610060 m1),CTNNB1 (beta catenin - Hs00170025 m1) and GUSB mRNA was evaluated with qPCR in three independent experiments. GUSB gene was used as the endogenous control.
Immunofluorescence Staining
For immunofluorescence assays, cells were cultured over cov- erslips added to 24-well plates. After treatment with cyclo- pamine the medium was removed and cells were fixed with meth- anol for 3 minutes, washed 3x with 0.01M phosphate buffered saline (PBS), and incubated with 10% normal horse serum for 1 hour. Slides were then incubated with anti-ß-catenin antibody (#610154 BD Biosciences, 1:2000) overnight at room tempera- ture, washed 3x with 0.01M PBS, incubated with AffiniPure donkey antimouse CyTM5-conjugated antibody (red color, 1:250, 715-175-150, Jackson ImmunoResearch, West Grove, PA) for 4 hours, washed with 0.01M PBS 3x and incubated with 4’,6-diamidino-2-phenylidone (DAPI, blue color, #4083 Cell Signaling Technology, Danvers, MA-1:25,000) for 2 minutes for nuclear counterstaining, then washed with PBS and mounted with Fluoromount (Sigma-Aldrich, St. Louis, MO). Staining was analyzed with a Leica TCS SP5 laser scanning confocal micro- scope (Leica Microsystems, Wetzlar, Germany) with a fixed time of exposure for all samples.
Cell viability assay
NCI-H295A cells were plated in 96-well plates at a density of 20,000 cells/well. After growth for 48 hours, the medium was replaced with medium containing 5 to 30 µM cyclopamine or 0.1% DMSO (control). After 24 to 96 hours, 20 µL of the Cell-
Titer 96 AQueous one solution (MTS, Promega, Madison, WI) was added to each well. After 2 hours of incubation, absorbance at 490nm was measured using a Sunrise microplate reader (Tecan, Salzburg, Austria) in two independent experiments. The half maximal inhibitory concentration (IC50) values were cal- culated in dose-response curves using CalcuSyn software (Bio- soft, Ferguson, MO).
Statistical analyses
Statistical analyses were performed using SAS software, ver- sion 9.2 (SAS Institute Inc., Cary, NC) and GraphPad Prism 5.02 (Graphpad, San Diego, CA). Continuous variables were ex- pressed as mean and range or standard deviation. Differences among variables were evaluated using linear regression (adding tumor weight and patient age for pediatric ACTs as control vari- ables, when appropriate); data values were log transformed be- fore tests. One-way ANOVA followed with Dunnett’s post-test were used in the in vitro study analyses. Overall survival was defined as the time from the date of diagnosis to death or last follow-up and analyses were carried out using Kaplan-Meier curves and the Log-rank test. The significance level was set at P < .05 for all analyses.
Results
Expression of SHH pathway proteins during normal adrenal development (Figure 1)
Hematoxylin-eosin staining confirmed the histomor- phology of human adrenal tissues. In general, SHH stain- ing was mainly found, although weakly, in the cytoplasm throughout the fetal and the definitive adrenal cortex. SHH staining tended to be more intense next to the capsule in later stages of fetal life and in the postnatal adrenal cortex.
The GLI family of transcription factors showed differ- ent staining patterns. In early fetal stages, GLI1 labeled all regions of the cortex, particularly the fetal zone. As the adrenal cortex developed, GLI1 staining tended to be stronger in the capsule and adjacencies. Independently of the developmental stages, GLI1 staining was weaker than GLI2 and GLI3 staining. GLI2 staining was positive in all regions during fetal stages. In earlier stages, it was stronger in the definitive cortex. In the postnatal adrenal, GLI2 staining was scattered throughout the cortex. In fetal ad- renals, GLI3 staining was weak in the capsule and strong in the definitive cortex, as well as in the fetal cortex. In postnatal adrenals, GLI3 staining remained intense throughout the cortex, but not in the capsule.
Adrenocortical tumors Clinical presentation of ACTs
Adults
Of the twenty adults evaluated, 18 were females (90%). Mean age at diagnosis was 35 years (17-66) and 90% of
20 - 25 weeks GA
26 - 31 weeks GA
32 - 37 weeks GA
Postnatal
20X
SHH
40X
A
B
C
D
GLI1
E
F
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H
GLI2
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P
these patients presented with hormone secreting tumors (androgen: 2, cortisol: 6, androgen and cortisol: 8, and inhibin: 2). MacFarlane stages were I in 5, II in 6, III in 4, and IV in 5 cases. The Weiss scores ranged from 1 to 8; six tumors were classified as ACA, thirteen as ACC and one was unspecified. Mean follow-up was 70.3 months. CT- NNB1 and the p.R337H P53 mutations were found in 35% and 20% of cases, respectively. Part of these clinical data had been previously reported (26) and are presented in the Supplemental Data (Table 1).
Pediatric
Of the 61 children evaluated, 48 were girls (79%) and mean age at diagnosis was 3.4 years (0.4-15.5). Fifty-nine (97%) patients had hormone secreting tumors (androgen: 33, cortisol: 2, androgen and cortisol: 24). Sandrine stages were I in 37, II in 8, III in 8, and IV in 8 cases. Mean follow-up was 69.9 months. A favorable prognosis was associated with age < 48 months (P < . 01), tumor weight < 200g (P <. 01), tumor stage I (P <. 01) and normal cortisol secretion (P = . 04). Weiss score was de- termined in a subset of 50 tumors and ranged from 3 to 9. All patients presenting a Weiss score < 6 survived and this score was associated with a good prognosis (P < . 01). CTNNB1 and the p.R337H P53 mutations were found in 6% and 85% of cases, respectively. Part of these clinical
data had been previously reported (3) and are presented in the Supple- mental Data (Table 2).
mRNA expression of SHH pathway genes
Normal Adrenal Cortices
Overall, the mRNA expression of SHH pathway genes was higher in pediatric than in adult normal adre- nal cortex samples (Figure 2A): SHH (P = . 01), PTCH1 (P = . 01), SMO (P < . 01), GLI1 (P <. 01), GLI2 (P = . 02) and GLI3 (P = . 01).
Adult ACTs
Adult ACCs presented higher mRNA expression levels of PTCH1 (P =. 04), SMO (P =. 03), GLI3 (P< .01) and SUFU (P < . 01) than nor- mal adult adrenal cortices. These dif- ferences were not observed compar- ing ACA and controls (Figure 2B). Noncarriers of the p.R337H P53 mutation presented higher GLI3 mRNA expression levels than carri- ers (P = . 04).
Pediatric ACTs
Pediatric ACTs presented lower mRNA expression lev- els of SHH (P <. 01), PTCH1 (P = . 03), SMO (P <. 01), GLI1 (P <. 01) and GLI3 (P = . 01) than normal adrenal cortices obtained from children (Figure 2C). Cortisol se- creting pediatric ACTs showed higher mRNA expression of PTCH1 (P <. 01) and SUFU (P = . 04). No differential mRNA expression was observed in association with p.R337H P53 and CTNNB1 mutations.
No association between mRNA expression of SHH pathway components and overall survival was observed in either the adult or pediatric ACT groups.
IHC
In agreement with the qPCR data, IHC showed that GLI1 and GLI3 staining was more frequent and intense in adult ACAs and ACCs, compared with pediatric ACTs. GLI1 and GLI3 labeling was positive in 30% and 87% of the pediatric ACTs and in 83% and 100%, and 100% and 100% of the adult ACAs and ACCs, respectively (Figure 3A and 3B).
A
Normal Adrenals
Pediatric controls
Relative mRNA level (log10)
100
Adult controls
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*
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**
*
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0.001
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PTCH1
SMO
GLI1
GLI2
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SUFU
B
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Controls
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Relative mRNA level (log10)
ACAs
ACCs
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PTCH1
SMO
GLI1
GLI2
GLI3
SUFU
C Pediatric ACTs
Relative mRNA level ( log10)
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0.010-
0.001
SHH
PTCH1
SMO
GLI1
GLI2
GLI3
SUFU
Adrenocortical tumor cell line -NCI-H295A
Inhibition of the SHH pathway impairs Wnt/B- catenin signaling
To evaluate a possible interaction between the SHH and Wnt/B-catenin pathways, we treated adrenocortical NCI-H295A cells with cyclopamine, a selective SMO in- hibitor. Twenty-four hour treatment with 20 µM cyclo- pamine caused a significant reduction of GLI3 mRNA expression (P = . 01) and of components of the Wnt path- way, SFRP1 (P = . 01) and CTNNB1 (P = . 03) (Figure 4A). Under basal conditions, immunofluorescence analy- sis showed strong cytoplasmic and nuclear ß-catenin staining. In agreement with the mRNA results, a 24-hour treatment with 20 uM cyclopamine resulted in decreased
ß-catenin staining, both in the cyto- plasm and the nucleus (Figures 4B).
Cyclopamine effect on cell viability
Cyclopamine treatment did not affect NCI-H295A cell viability in the first 24 hours (Figure 4C). How- ever, a dose dependent reduction in cell viability was observed after 96 hours in cells treated with 20 AM (24 ± 16%; P < . 01) and 30 p.M (30 ± 7; P < . 001) cyclopamine, compared with the control (Figure 4D). The IC50 was 61 µM (r = 0.95) after 96 hours of incubation.
Discussion
The expression pattern of the SHH pathway genes in different stages of Controls ACTs development of the human adrenal cortex or in pediatric ACTs had not been explored to date. The present study shows that the SHH pathway is active in fetal and postnatal human adrenal cortices. In human fetuses, the expression of SHH components in the adrenal cortex was detected from midgestation and continued throughout postnatal life. Interest- ingly, the mRNA expression levels of SHH components were higher in the normal adrenal cortices from chil- dren than in those from adults. In agreement with our findings, studies in animal models indicated that the SHH pathway is active and plays a role in the development and maintenance of the adrenal cortex (12-14). Similarly to what had been detected in earlier stages of adrenal cortex development in rodents (12), we detected SHH protein expression in the human fetal adrenal cortex during the earlier fetal stages. In con- trast, SHH protein expression tended to be more intense next to the capsule in later stages of fetal development and in the postnatal adrenal cortex. This finding is in agree- ment with a previous report showing the presence of SHH mRNA expression in the periphery of the adult human adrenal cortex (27).
GLI1, a transcription factor induced by SHH, is con- sidered to be a marker of SHH activation (11). In agree-
ment with rodent models and a study in adult human ad- renals (12, 13, 28), we found GLI1 protein expression mostly in the capsule and adjacencies in postnatal adre- nals. The same pattern was also observed in later fetal stages. However, in earlier developmental stages, GLI1 staining was detected mostly in the fetal adrenal cortex. GLI1-positive cells have been considered a marker of pro- genitor cells (14). Therefore, our data suggest that in ear- lier stages of fetal life, stem/progenitor cells are present in the entire human adrenal cortex, but later become re- stricted to the capsule. These findings agree with the hy- pothesis that the adult cortex arises from both cells of the fetal cortex and cells of the capsule/subcapsular region (29-31).
Positive protein expression of GLI2 and GLI3 was found during all stages of development in the analyzed adrenal cortices. Interestingly, in postnatal adrenals, GLI3 expression remained strong throughout the cortex, but not in the capsule. In mouse models, GLI2 and GLI3 mRNA levels were detected in the subcapsular region of the cortex during embryonic stages and at birth, but not in the adult adrenal cortex (12). In fact, GLI3 seems to be important for human adrenal development, since some patients harboring GLI3 inactivating mutations present with adrenal hypoplasia (18). It is unclear whether GLI3 is important in adrenal zonation. However, in neural and
| Pediatric ACTs | ||||
|---|---|---|---|---|
| IHC staining intensity (n=23) | ||||
| 1+ | 2+ | 3+ | Total (%) | |
| SHH | 7 | 1 | 8 (35) | |
| GLI1 | 6 | 1 | 7 (30) | |
| GLI3 | 5 | 9 | 6 | 20 (87) |
A
B
SHH
20X
GLIÍ
20X
GLI3
20X
| Adult ACAs | ||||
|---|---|---|---|---|
| IHC staining intensity (n=6) | ||||
| 1+ | 2+ | 3+ | Total (%) | |
| SHH | 1 | 1 | 2 (33) | |
| GLI1 | 4 | 1 | 5 (83) | |
| GLI3 | 2 | 3 | 1 | 6 (100) |
| Adult ACCs | ||||
|---|---|---|---|---|
| IHC staining intensity (n=5) | ||||
| 1+ | 2+ | 3+ | Total (%) | |
| SHH | 3 | 3 (60) | ||
| GLI1 | 3 | 1 | 1 | 5 (100) |
| GLI3 | 4 | 1 | 5 (100) | |
Figure 3. Immunohistochemical analysis in ACTs. A: Representative image of SHH, GLI1 and GLI3 immunostaining in ACTs (20x magnification). Protein staining was developed with DAB (brown) and counterstained with Harris hematoxylin (blue). Staining intensity classification: SHH (2+: moderate), GLI1 (3+: strong) and GLI3 (3+: strong); B: Percentage and intensity of positive SHH, GLI1 and GLI3 protein staining in pediatric and adult ACTs.
bone tissues, GLI3 modulates the temporal kinetics of cell differentiation by interacting with the WNT and FGF pathways (32, 33).
Analyzing the expression of SHH pathway genes in ACCs of adult patients, we found positive GLI1 protein expression in all tumors, as well as increased PTCH1 mRNA expression and normal SHH expression in ACCs when compared with normal adrenal cortices. Con- versely, in aldosterone producing adenomas, which were not evaluated in our study, SHH staining was found in all analyzed samples (27). The expression of PTCH1, SMO, GLI3 and SUFU mRNA was higher in adult ACCs than in normal adrenal cortices. This differential expression was not observed in ACAs when comparing with normal ad- renals. However, due to the small number of ACAs ana- lyzed, this result should be further tested and confirmed. Previously, microarray studies found higher GLI2 mRNA expression in ACCs compared with ACAs (9, 34, 35) and with normal adrenal cortices (34). In addition, Soon et al (2009) found lower expression of SHH and PTCH1 mRNA in ACCs than in ACAs (35). We did not find these differences.
All but two adult patients evaluated in our series pre- sented with secreting tumors. Of note, a recently published study analyzing a small number of samples found evidence of SHH pathway activity in nonsecreting adrenocortical adenomas (28). Differing from the adult group, pediatric ACTs were observed to have lower expression of most SHH pathway genes, as compared with normal pediatric adrenal cortices. Noteworthy, most of the pediatric ACTs in our cohort are associated with a specific, low penetrance TP53 mutation (p.R337H), which could characterize a specific subtype of childhood ACTs. However, our finding is in agreement with data from a microarray analysis that also found lower expression of PTCH1 mRNA in pedi- atric ACTs compared with normal adrenals (36). Our data reinforces that pediatric and adult ACTs differ in both origin and clinical behavior (37). The mechanism under- lying the involvement of the SHH pathway in ACTs is unknown, but might be related to abnormal Wnt/ß- catenin signaling.
Previous studies suggested an interaction between SHH and WNT pathways (38-40). In order to evaluate a pos- sible interaction of SHH and WNT pathways in adreno- cortical tumor cells, we treated NCI-H295A cells with cyclopamine. Our data showed that SMO inhibition re- sulted in decreased CTNNB1 mRNA expression and cy- toplasmic and nuclear ß-catenin staining. Thus, SMO in- hibition in adrenocortical tumor cells may impair WNT/ ß-catenin signaling. In addition, cyclopamine treatment also resulted in a decrease of GLI3 mRNA expression. Of note, we found increased expression of GLI3 mRNA lev-
A
24h
☐ DMSO
C
Cyclopamine 5
24h
2.0
Cyclopamine 20
150-
Relative mRNA level
1.5
Cell Viability (%)
**
**
*
100-
1.0
50-
0.5
0.0
GLI1
GLI3
SFRP1
CTNNB1
0
DMSO
5
20
30
Cyclpamine (uM)
B
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Beta-catenin
DAPI
Merge
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DMSO
Cell Viability (%)
100-
”
50-
Cyclopamine
20
0
DMSO
5
20
30
Cyclopamine (uM)
els in adult ACCs and GLI3-positive staining in all eval- uated adult ACTs. Conversely, GLI3 expression was de- creased in pediatric ACTs. Interestingly, the prognosis of pediatric patients is usually better than in adults (37). Our original result showing GLI3 overexpression in adult ACTs may be important, since GLI3 overexpression has been associated with cell survival, epithelial mesenchymal transition and tumor chemical resistance in other tumors types (41, 42).
Our data showing decreased NCI-H295A cell viability after cyclopamine treatment is in agreement with a re- cently published study by an independent group (28). We must consider that cyclopamine may induce nonspecific toxicity (43), but the concentrations used in our study were moderate and cell viability impairment occurred only after 96 hours of incubation, suggesting a direct SMO inhibition effect. These data should be further explored, particularly by in vivo animal studies. Of note, several Hedgehog pathway inhibitors are currently undergoing phase I and II clinical trials for treatment of different neo- plasms (44).
In conclusion, we demonstrated that the SHH pathway is active in human adrenals and presents distinct spatio- temporal expression patterns throughout adrenal devel- opment. In addition, we showed that the SHH pathway is deregulated in ACTs and in vitro SHH pathway inhibition impaired WNT/B-catenin signaling and reduced tumor cell viability. Thus, the SHH pathway appears to be im-
portant in adrenocortical tumori- genesis and may be a potential target in adjuvant therapy for adrenocorti- cal carcinomas.
Acknowledgments
We thank Professor Claudimara Lotfi for providing the NCI-H295A cell line, Wendy Turatti and Rogerio Zuliani for their technical assistance and Silvia G. Ruginsk and Rodrigo C. Rorato for their kind help. We also thank Leandro M. Colli for his help with the microarray studies and data mining and the statisti- cian Davi C. Aragon for help with the statistical analysis.
Address all correspondence and re- quests for reprints to: Sonir R. Antonini, MD, PhD, Faculdade de Medicina de Ri- beirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900 - Monte Alegre, CEP14049-900, Ribeirão Preto - São Paulo, Brasil, email: antonini@fmrp.usp.br.
Disclosure Summary: The authors have nothing to disclose.
This work was supported by FINANCIAL SUPPORT: Sao Paulo State Research Council (FAPESP), grant 2011-13807-4 and Conselho Nacional de Desenvolvimento Cientifico e Tec- nologico (CNPq), grant 2011-474273.
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