A Novel Monoclonal Antibody Against DOG1 is a Sensitive and Specific Marker for Gastrointestinal Stromal Tumors

Article (PDF Available)inAmerican Journal of Surgical Pathology 32(2):210-8 · March 2008with67 Reads
DOI: 10.1097/PAS.0b013e3181238cec · Source: PubMed
Gastrointestinal stromal tumors (GIST) occur primarily in the wall of the intestine and are characterized by activating mutations in the receptor tyrosine kinases genes KIT or PDGFRA. The diagnosis of GIST relies heavily on the demonstration of KIT/CD117 protein expression by immunohistochemistry. However, KIT expression is absent in approximately 4% to 15% of GIST and this can complicate the diagnosis of GIST in patients who may benefit from treatment with receptor tyrosine kinase inhibitors. We previously identified DOG1/TMEM16A as a novel marker for GIST using a conventional rabbit antipeptide antiserum and an in situ hybridization probe. Here, we describe 2 new monoclonal antibodies against DOG1 (DOG1.1 and DOG1.3) and compare their staining profiles with KIT and CD34 antibodies on 447 cases of GIST. These included 306 cases with known mutational status for KIT and PDGFRA from a molecular consultation service. In addition, 935 other mesenchymal tumors and 432 nonsarcomatous tumors were studied. Both DOG1 antibodies showed high sensitivity and specificity for GIST, with DOG1.1 showing some advantages. This antibody yielded positive staining in 370 of 425 (87%) scorable GIST, whereas CD117 was positive in 317 of 428 (74%) GIST and CD34 in 254 of 430 (59%) GIST. In GIST with mutations in PDGFRA, 79% (23/29) showed DOG1.1 immunoreactivity while only 9% (3/32) and 27% (9/33) stained for CD117 and CD34, respectively. Only 1 of 326 (0.3%) leiomyosarcomas and 1 of 39 (2.5%) synovial sarcomas among the 935 soft tissue tumors examined showed positive immunostaining for DOG1.1. In addition, DOG1.1 immunoreactivity was seen in fewer cases of carcinoma, melanoma, and seminoma as compared with KIT.
A Novel Monoclonal Antibody Against DOG1 is a Sensitive
and Specific Marker for Gastrointestinal Stromal Tumors
Inigo Espinosa, MD,* Cheng-Han Lee, MD, PhD,* Mi Kyung Kim, MD, PhD,*
Bich-Tien Rouse, MS,* Subbaya Subramanian, PhD,* Kelli Montgomery, BA,*
Sushama Varma, MS,* Christopher L. Corless, MD, PhD,
Michael C. Heinrich, MD,
Kevin S. Smith, PhD,* Zhong Wang, PhD,* Brian Rubin, MD, PhD,
Torsten O. Nielsen, MD, PhD,
Robert S. Seitz, MD,J DouglasT.Ross,MD,PhD,J Robert B. West, MD, PhD,*
Michael L. Cleary, MD,* and Matt van de Rijn, MD, PhD*
Abstract: Gastrointestinal stromal tumors (GIST) occur pri-
marily in the wall of the intestine and are characterized by
activating mutations in the receptor tyrosine kinases genes KIT
or PDGFRA. The diagnosis of GIST relies heavily on the
demonstration of KIT/CD117 protein expression by immuno-
histochemistry. However, KIT expression is absent in B4% to
15% of GIST and this can complicate the diagnosis of GIST in
patients who may benefit from treatment with receptor tyrosine
kinase inhibitors. We previously identified DOG1/TMEM16A
as a novel marker for GIST using a conventional rabbit
antipeptide antiserum and an in situ hybridization probe. Here,
we describe 2 new monoclonal antibodies against DOG1
(DOG1.1 and DOG1.3) and compare their staining profiles
with KIT and CD34 antibodies on 447 cases of GIST. These
included 306 cases with known mutational status for KIT and
PDGFRA from a molecular consultation service. In addition,
935 other mesenchymal tumors and 432 nonsarcomatous
tumors were studied. Both DOG1 antibodies showed high
sensitivity and specificity for GIST, with DOG1.1 showing some
advantages. This antibody yielded positive staining in 370 of 425
(87%) scorable GIST, whereas CD117 was positive in 317 of 428
(74%) GIST and CD34 in 254 of 430 (59%) GIST. In GIST
with mutations in PDGFRA, 79% (23/29) showed DOG1.1
immunoreactivity while only 9% (3/32) and 27% (9/33) stained
for CD117 and CD34, respectively. Only 1 of 326 (0.3%)
leiomyosarcomas and 1 of 39 (2.5%) synovial sarcomas among
the 935 soft tissue tumors examined showed positive immuno-
staining for DOG1.1. In addition, DOG1.1 immunoreactivity
was seen in fewer cases of carcinoma, melanoma, and seminoma
as compared with KIT.
Key Words: GIST, DOG1, monoclonal antibody, immunohisto-
(Am J Surg Pathol 2008;32:210–218)
astrointestinal stromal tumor (GIST) is the most
common mesenchymal tumor arising in the gastro-
intestinal tract. Most contain an activating mutation in
the juxtamembrane domains of either KIT or PDGFRA
that result in constitutive, ligand-independent activation
of these recept or tyrosine kinases (RTK).
mesylate (Gleevec), a small molecule inhibitor with
activity against KIT and PDGFRA is the primary
therapy for metastatic or unresectable GIST.
more, the use of imatinib as a neoadjuvant or adjuvant
therapy is being examined in ongoing clinical trials. The
next generation of RTK inhibitors, including drugs such
as sunitinib (Sutent), is providing options for GIST
patients who fail imatinib therapy.
With the growing
effectiveness and availability of RTK directed therapies,
the accurate diagnosis of GIST has become imperative.
Histologically, GIST demonstrates considerable
morphologic overlap with other tumors. Mutation screen-
ing of KIT or PDGFRA can serve in confirming the
diagnosis of GIST, but only a few centers in United States
perform this analysis clinically. Moreover, up to 15%
of GIST lack a mutation in both of these kinase genes
(socalled wild-type GIST). In routine practice, the
diagnosis of GIST is based on the anatomic location of
the tumor and immunohistochemical evidence of KIT
(CD117) and/or CD34 expression. CD34 is not a specific
marker for GIST and is positive in many other soft tissue
tumors that may enter into the differential diagnosis of
Consequently, its utility in the diagnosis of GIST
is limited. In contrast, within the sarcomas, KIT is a
relatively specific marker for GIST. However, about
B4% to 15% of GIST in reported series sho w weak
or negative staining for KIT/CD117.
Many of theseCopyright
2008 by Lippincott Williams & Wilkins
From the *Department of Pathology, Stanford University Medical
Center, Stanford; JApplied Genomics Inc, Burlingame, CA;
wDepartment of Pathology and OHSU Cancer Institute, Oregon
Health and Science University, Portland, OR; zDepartments of
Anatomic Pathology and Molecular Genetics, Lerner Research
Institute and Taussig Cancer Center, Cleveland Clinic, Cleveland,
OH; and yDepartment of Pathology, University of British Columbia,
Vancouver, Canada.
Supported by Grants from the Life Raft Group and NIH grant
Reprints: Prof Matt van de Rijn, MD, PhD, Department of Pathology,
L-235, Stanford University Medical Center, 300 Pasteur Drive,
Stanford, CA 94305 (e-mail: mrijn@stanford.edu).
210 Am J Surg Pathol
Volume 32, Number 2, February 2008
‘‘KIT-negative’’ GIST possess PDGFRA mutations and
a subset of these cases is sensitive to treatment with
Diagnosis of these tumors remains a
significant challenge.
Using gene expression profiling, we previously
identified DO G1 (TMEM16A) as a gene with high levels
of expression in GIST and developed a rabbit polyclonal
antibody and an in situ hybridization probe that target
This study involving a series of 149 GIST and
438 other mesenchymal tumors showed that the poly -
clonal DOG1 antibody was superior in sensitivity and
specificity compared with commercially available anti-
CD117 polyclonal antiserum. However, we were unable
to generate large amounts of polyclonal anti-DOG1
antiserum. Here, we describe 2 novel mouse monoclonal
antibodies against DOG1 (DOG1.1 and DOG1.3) that
have superior sensitivity and specificity compared with
anti-CD117 and anti-CD34 reagents in a large series of
GIST and other tumors. Our results indicate that
monoclonal DOG1 antibodies are useful diagnostic
markers for GIST and will help to identify additional
patients with GIST who may benefit from targeted
Case Material
The cases analyzed for this study consisted of 447
GIST, 935 other mesenchymal tumors (Table 1), and 432
nonsarcomatous tumors distributed over 10 tissue micro-
arrays (TMAs). A diagnosis of GIST was made based on
tumor location, morphology, and immunostaining for
KIT. For 306 GIST cases, mutation al analysis of the KIT
and PDGFRA genes was obtained. Of the 39 mutation-
negative (WT) tumors, 27 were located in the wall of the
intestine and showed no histologic or immunophenotypic
support for smooth muscle differentiation, 24 of these
cases showed staining for KIT or CD34. The 12
remaining WT tumors were metastatic lesions or were
located in the abdomen without a definite site. Eight of
these 12 tumors were positive by immunostaining for KIT
and/or CD34. The remaining 4 were accepted as GIST
based on histologic features alone. The TMAs were
constructed using a manual tissue arrayer from Beecher
Instrument, Silver Spring, MD. Cores of 0.6 mm were
taken from paraffin-embedded soft tissue tumors from the
Stanford University Medical Center, the Oregon Health
and Science University, Portland, Oregon, and the
University of British Columbia, Vancouver. A significant
proportion of GIST (306 cases) had been submitted for
molecular consultation (C.L.C., M.C.H.) and had known
mutational status for the KIT and PDGFRA genes. The
GIST were analyzed for mutations in exons 9, 11, 13, and
17 of the KIT gene using a combination of denaturing
high pressure liquid chromography and direct sequencing,
as previously described.
KIT wild-type tumors were
subsequently screened for mutat ions in exons 12, 14, and
18 of the PDGFRA gene.
Slides were cut at 4 mm, deparaffinized in xylene,
and hydrate d in a graded seri es of alcohol. The primary
antibodies used were DOG 1.1 (mouse monoclonal, 1/50;
Stanford University), DOG1.3 (mouse monoclonal, 1/1
supernatant; Applied Genomics Inc), CD117 (rabbit
polyclonal, 1/400; DAKO, Carpinteria, CA), and CD34
(mouse monoclonal, 1/80; clone 581/CD34, BD Bio-
sciences, San Jose, CA). The antigen retrieval solution for
DOG1.1, DOG1.3, and CD34 was citrate, pH: 6 and for
CD117 was EDTA, pH:8. Slides were boiled by micro-
waving in antigen retrieval solution for 12 minutes. The
immunohistochemical reactions were visualized using
rabbit or mouse versions of the biotin-free EnVision+
system (DAKO, Carpinteria, CA) using diaminobenzidine.
In Situ Hybridization
In situ hybridization of TMA sections was per-
formed based on a protocol publis hed previously.
Scoring of Immunohistochemistry
and In Situ Hybridization
Cores wer e scored as follows: 0 indicates the
absence of any staining; 1 indicates equivocal staining;
TABLE 1. Mesenchymal Tumors Other Than GIST Included
in the Study
Tumors No. Cases
Alveolar soft part sarcoma 2
Phyllodes tumor 2
Pleomorphic liposarcoma 3
Epithelioid sarcoma 3
Fibrosarcoma 3
Chondrosarcoma 3
Inflammatory pseudotumor 5
Clear cell sarcoma 7
Dedifferentiated liposarcoma 10
Myxoid liposarcoma 10
Ewing/PNET 10
Desmoplastic melanoma 10
Well-differentiated liposarcoma 11
Extraskeletal myxoid chondrosarcoma 11
Low-grade fibromyxoid sarcoma 11
Fibroadenoma 11
Epithelioid hemangioendothelioma 12
Endometrial stroma sarcoma 13
Rhabdomyosarcoma 13
Angiosarcoma 14
Osteosarcoma 14
Dermatofibrosarcoma protuberans 20
Solitary fibrous tumor 21
Leiomyoma 22
Desmoid fibromatosis 35
Synovial sarcoma 44
Schwannoma 46
Neurofibroma 55
Malignant peripheral nerve sheath tumor 86
Undifferentiated sarcoma 87
Leiomyosarcoma 334
DSRCT indicates desmoplastic small round cell tumor; PNET, primitive
neuroectodermal tumor.
Am J Surg Pathol
Volume 32, Number 2, February 2008 DOG1 is a Sensitive and Specific Marker for GIST
2008 Lippincott Williams & Wilkins 211
2 indicates any moderate membranous staining whether
diffusely or focally present in the tumor; 3 indicates
strong complete membranous stai ning whether diffusely
or focally present in the tumor (Figs. 1A–D). Score 2 and
3 were considered positive. The cores wer e independently
reviewed for 2 pathologist s (I.E. and C.H.L.) and any
disagreements were reviewed together with a third
pathologist (M.v.d.R.) to achieve a con sensus score.
Digital images of stained cores can be viewed at http://
FIGURE 1. DOG1.1 immunohistochemistry in GIST ( 40). A, Score 0. B, Score 1. C, Score 2. D, Score 3. E, Strong membranous
staining in an epithelioid GIST. F, Strong cytoplasmic staining in a spindle cell GIST.
Espinosa et al Am J Surg Pathol
Volume 32, Number 2, February 2008
2008 Lippincott Williams & Wilkins
Antibody Generation
The peptides sequences to generate the DOG1.1 and
DOG1.3 monoclonal antibodies were MSDFVDWVIP
VKIHAP, respectively. These peptides were injected
intraperitoneally with Freund complete adjuvant into a
mouse and boosted 4 times weekly. Spleens were taken
for hybridoma preparation as described by Ko
hler and
The fused cells were distributed in 96-well plates and
the antibody producing wells were detected by enzyme-
linked immunosorbent assay using DOG1 peptide-coated
plates. Positive wells were next screened by immun ohis-
tochemistry on a mini-TMA containing 5 cases of GIST
and 2 cases of leiomyosarcoma.
Clinicopathologic Features of the GIST Cases
All but 2 of the 447 cases of GIST cases were
primary tumors. The 2 exceptions were a liver metastasis
and an abdominal metastasis of GIST (Table 2). In
the cases with available clinicopathologic information,
the features were typical of GIST. The median age of the
patients was 59 years (range, 3 to 95 y) and the majority of
the patients were over 60 years old. There was equal sex
distribution and the tumor size ranged from 0.4 to 32 cm
(median, 6.5 cm). The most common location for the
tumor in this series was stomach (53%), followed by small
bowel (30%), large bowel (8%), nongastrointestinal
(7%), esophagus (1%), and gallbladder (1%).
DOG1 Staining in GIST in Comparison
With KIT and CD34
DOG1.1 reactivity was seen in 370 GISTs cases
(370/425; 87%), whereas the expression of KIT and CD34
was found in 317 (317/428; 74%) and 254 cases (254/430;
59%), respectively. In the major ity of cases, immunohis-
tochemistry with DOG1.1 resulted in strong staining
involving the majority of tumor cells [282 GIST with
strong staining, score 3(66%) and 88 GIST with moderate
staining, score 2 (21%)]. Examples of different staining
intensities are shown in Figures 1A to D. The predomi-
nant staining pattern of DOG1 was membranous. This
staining pattern was most evident in the epithelioid GIST
cases, whereas in the spindled cell cases the membranous
staining was often accompanied by cytoplasmic staining
(Figs. 1E, F). This staining pattern is in keeping with the
DNA sequence for DOG1/TMEM16, which predicts 8
transmembrane regions.
The reactivity of DOG1.1, KIT, and CD34 with
GISTs containing a mutation in the KIT gene was 92%
(200/218), 81% (180/221), and 64% (142/224), respec-
tively. In the wild-type GISTs, DOG1.1 was expressed in
33 of 37 cases (89%), KIT in 29 of 35 cases (83%), and
CD34 in 20 of 38 cases (51%). DOG1.1 expression was
not related to the type of mutation (Table 3A), site, or size
of the tumor (Table 3B), the grade of the tumor, or the
age of the patient. The DOG1.3 monoclonal antibody
showed a very similar reactivity in KIT mutation positive
and WT-GIST, of 88% (197/223) and 84% (31/37) of
cases, respectively. Overall, only 6 GIST cases that were
negative for DOG1.1 were positive for DOG1.3 and 3 of
these were positive for KIT. The DOG1.3 therefore gave
a minimal increase in the number of cases recognized as
GIST and was omitted from further studies.
Importantly, in GIST with PDGFRA mutations,
DOG1.1 was positive in 23 of 29 scorable GISTs (79%),
whereas KIT was positive only in 3 of 32 cases (9%).
CD34 was positive in 9 of 33 cases (27%) (Figs 2, 3). In
contrast, the other monoclonal antibody against DOG1,
DOG1.3, was positive in only 12 of 29 (41%) cases with
PDGFRA mutations. Among 19 PDGFRA-mutant GIST
that were positive for DOG1.1 and had failed to react for
KIT, 7 harbored mutations predicted to be sensitive to
: 4 exon 12 mutations [V561D (2 cases),
InsER561-562 (1 case), and SPDGHE566 -571R (1 case)],
and 3 exon 18 mutations (all Del DIMH842-845). Eleven
of the 19 cases ha d exon 18 mutations [D842V (10 cases)
and Del HDSN844-848P (1 case)] and 1 case had a
mutation in exon 12 (Del RV560-561). These confer
imatinib resistance; nevertheless, the findings suggest that
DOG1.1 can identify KIT-negative GIST that may
respond to kinase inhibitor therapy.
Data on PDGFRA expression in GIST are scant
because of the absence of a reliable antibody for
PDGFRA in paraffin-embedded tissue. By in situ
TABLE 2. Clinicopathologic Features of GIST Cases
Total No. Patients 447
Age (n = 341; 3-95 y; median: 59)
<18 y 9 (3%)
Z 18 to <40 y 31 (9%)
Z 40 to <60 y 139 (41%)
Z 60 y 162 (48%)
Sex (n = 357)
Female 179 (50%)
Male 178 (50%)
Size (n = 303)
r2 cm 21 (7%)
>2 to r5 cm 94 (31%)
>5 to r10 cm 96 (32%)
>10 cm 92 (30%)
Location (n = 337)
Stomach 179 (53%)
Small bowel 101 (30%)
Large bowel 27 (8%)
EGIST 24 (7%)
Esophagus 3 (1%)
Gallbladder 3 (1%)
Risk (n = 70)
Very low 5 (7%)
Low 30 (43%)
Intermediate 10 (14%)
High 25 (36%)
EGIST indicates extragastrointestinal GIST.
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Volume 32, Number 2, February 2008 DOG1 is a Sensitive and Specific Marker for GIST
2008 Lippincott Williams & Wilkins 213
hybridization on the current set of TMAs, we found
results similar to those reported by West et al.
majority of the PDGFRA-mutant GISTs were positive for
PDGFRA expression by in situ hybridization (24/32;
75%). PDGFRA expression was also seen in 37 GIST
with mutations in the KIT gene. In our prior study,
we showed that other sarcomas like leiomyosarcomas
(LMS), undifferentiated sarcomas, synovial sarcoma (SS),
and liposarcomas also express PDGFRA by in situ
PDGFRA expression therefore is not a
specific marker for GIST.
DOG1.1 Staining on Other Soft Tissue Tumors
A variety of soft tissue tumors fall within the
morphologic differential diagnosis of GIST. These
include smooth muscle tumors, nerve sheath tumors,
desmoid fibromatosis, undifferentiated sarcomas, inflam-
matory pseudotumors, solitary fibrous tumor, melanoma,
SS, dedifferentiated liposarcoma, and dermatofibrosarco-
ma protuberans (Table 4A) . DOG1.1 was expressed in
1/326 LMS (0.3%), 1/39 SS (2.5%), and in 1 desmoplastic
melanoma (1/10; 10%). In contrast, expression of KIT
was found in 3/331 LMS (0.9%), 1/87 undifferentiated
sarcomas (1.1%), and in 1 desmoplastic melanoma (1/10;
10%). CD34 was more widely expressed. It was found in
5 LMS (1.5%), 9 undifferentiated sarcomas (11%), 11
malignant peripheral nerve sheath tumors (13%), 38
neurofibromas (69%), 1 SS (2.2%), 4 schwannomas (9%),
12 solitary fibrous tumor (60%), 15 dermatofibrosarcoma
protuberans (88%), 3 dedifferentiated liposarcomas
(37%), and 1 desmoplastic melanoma (10%).
DOG1 Staining in Nonsarcomatous Tumors
We compared the reactivity of DOG1.1 on 432 cases
of nonsarcoma lesions and compared it with staining
results obtained with KIT and CD34 antibodies. The
TMA contained a wide variety of carcinomas, from 25
primary sites and a limited number of lymphomas, brain
tumors, and other types of tumors. Within all tumor
types, only rare cases with DOG 1.1 reactivity were seen,
summarized in Table 5 (a complete table of the staining
results is available as Web supplement Table 1). Most of
the cases were ne gative for DOG1.1. In contrast,
occasional cases of liver, pancreas, kidney, bladder,
endometrial, and other carcinomas stained for KIT. As
reported previously by others
a significant number
of seminomas (18/21) and melanomas (8/21) stained for
KIT, whereas only 1 desmop lastic melanoma and no
seminomas were positive for DOG1.1. This is clinically
relevant as melanomas and retroperitoneal seminomas
can be part of the differential diagn osis for GIST.
DOG1 mAb Staining in Interstitial Cells of Cajal
in Non-neoplastic Gastrointestinal Tract
In non-neoplastic esophagus, stomach, small bowel,
and colon, the staining obtained with DOG1.1 was highly
similar to that seen with KIT antiserum. In the small
bowel (Fig. 4), the DOG1.1 and KIT positive cells were
TABLE 3. Staining Results for KIT, CD34, and DOG1.1 Based on Genotype (A) and Primary Tumor Location (B)
KIT exon 11 (n = 207) 180/197 (91%) 158/196 (81%) 129/200 (65%) 183/189 (97%)
KIT exon 9 (n = 20) 16/16 (100%) 17/19 (89%) 10/18 (61%) 15/15 (100%)
KIT exon 13 (n = 6) 4/5 (80%) 5/6 (83%) 3/6 (50%) 5/5 (100%)
PDGFRa exon 18 (n = 26) 18/23 (78%) 3/24 (13%) 8/26 (31%) 18/22 (82%)
PDGFRa exon 12 (n = 7) 5/5 (100%) 0/7 (0%) 1/6 (17%) 5/5 (100%)
PDGFRa exon 14 (n = 1) 0/1 (0%) 0/1 (0%) 0/1 (0%) 0/1 (0%)
WT (n = 39) 33/37 (89%) 29/35 (83%) 20/38 (53%) 31/33 (94%)
Unknown (n = 141) 112/139 (81%) 104/138 (75%) 81/133 (61%) 118/133 (89%)
Stomach (n = 179) 148/169 (88%) 120/169 (71%) 140/174 (80%) 157/164 (96%)
Small bowel (n = 101) 88/97 (91%) 78/95 (82%) 28/95 (29%) 85/88 (97%)
Large bowel (n = 27) 21/27 (78%) 18/27 (67%) 16/27 (59%) 21/27 (78%)
EGIST (n = 24) 16/21 (76%) 12/23 (52%) 14/23 (61%) 17/20 (85%)
Esophagus (n = 3) 1/2 (50%) 2/3 (67%) 3/3 (100%) 2/2 (100%)
Gallbladder (n = 3) 2/3 (67%) 2/3 (67%) 2/3 (67%) 2/3 (67%)
Unknown (108) 93/104 (89%) 84/106 (79%) 50/103 (49%) 91/99 (92%)
EGIST indicates extragastrointestinal GIST.
FIGURE 2. Immunohistochemical results for KIT, CD34, and
DOG1.1 in KIT or PDGFRA mutation positive and KIT/PDGFRA
mutation negative (WT) GISTs.
Espinosa et al Am J Surg Pathol
Volume 32, Number 2, February 2008
2008 Lippincott Williams & Wilkins
located in the myenteric plexus, between the circular and
longitudinal muscle layer. These cells possess numerous
thin cytoplasmic processes and form a cellular network
around the ganglion cells of the myenteric plexus.
However, in contrast to DOG1 mAb, KIT pAb also
stained numerous mast cells and the basal portion of the
gastric epithelium, as reported previously.
This is in
contrast with our experience with the original DOG1
rabbit antiserum, wher e mast cells reacted as well.
TMA with 31 different normal human tissues failed to
show DOG1 reactivity other than that described in the
myenteric plexus.
With the recent development of effective targeted
therapies for GIST,
the correct diagnosis of these tumors
has a considerable clinical impact. Most GIST can be
identified based on the combination of tumor location,
histologic appearance, and the presence of KIT by
However, in a significant pro-
portion of GISTs (B4% to 15%), KIT expression is
equivocal or negative, leaving the diagnosis in question.
Screening for KIT and PDGFRA mutations can be
helpful in this setting, but this approach adds to the time
and cost of diagnosis and is better reserved for use in
decisions concerning kinase inhibitor therapy. What is
needed to aid in routine diagnosis is a marker that reliably
stains GIST that are KIT-weak/negative.
DOG1 is a protein of unknown function that was
found to be selectively expressed in GIST using gene
expression profiling.
The DOG1 gene (aka TMEM16),
is localized on the chromosome 11 (11q13). It contains
26 exons and encodes for a 960 amino acid protein
with an expected size of 114 Kb. On the basis of
DNA sequence analysis, the protein has 8 trans-
membrane domains. Its function is unknown but the
high number of transmembrane regions suggest that
it may be an ion channel.
Human DOG1 protein
shows homology with other proteins including TMP16B
FIGURE 3. Patterns of DOG1.1, KIT, and CD34 in GISTs with different genotypes ( 40). A, KIT exon 11 mutant with expression
of DOG1.1, KIT, and CD34. B, KIT exon 11 mutant with expression of DOG1.1, and negative for KIT and CD34. C, PDGFRA exon
18 mutant with expression of DOG1.1 and negative for KIT and CD34.
Am J Surg Pathol
Volume 32, Number 2, February 2008 DOG1 is a Sensitive and Specific Marker for GIST
2008 Lippincott Williams & Wilkins 215
(79%), TMP16E (57%), TMP16C (57%), TNP16F
(56%), the gene encoding for hypothetical protein
C691.05C (44%), and TMP16H (41%), but shows no
homology at the DNA or amino acid level with KIT . The
human DOG1 protein has a high degree of homology
with the mouse DOG1 protein (89%). The 11q13 locus is
amplified in several cancers: head and neck squamous cell
carcinoma, bladder tumors, and breast cancer, but we
failed to demonstrate DOG1 expression in these tumors
by immunohistochemistry.
The rabbit serum used in our previous studies
proved difficult to generate in additional rabbits, despite
repeated immunization attempts with the original DOG1
peptide. We therefore generated 2 monoclonal antibodies
(DOG1.1 and DOG1.3) against different peptide sequen-
ces of DOG1. Both antibodies showed high specificity in
the immunostaining of GIST. In particular, the DOG1.1
monoclonal antibody has potential for clinical use in the
routine diagnosis of GIST.
Among GIST cases with KIT mutations, most
of which are imatinib sensitive, the DOG1.1 antibody
identified 11% more cases than KIT. GIST cases with
mutations in PDGFRA differ in their gene expression
profile from KIT-mutant GIST,
are often weak or
negative for KIT by immunohistochemistry, and tend to
have an epithelioid morphology.
As such, they
are more likely to be misdiagnosed for epithelial
neoplasms. In our study, only 9% of PDGFRA -mutant
GIST (3/32) were positive for KIT, whereas DOG1.1 was
positive in the majority (23/29; 78%). Moreover, a third
of the PDGFRA-mutant GIST that were DOG1+ and
KIT harbored mutations predicted to be imatinib
The lack of KIT staining in these cases might
otherwise consign them to a non-GIST diagnosis,
potentially denying patients the opportunity to be treated
with imatinib.
The high number of KIT-negative GIST in our
study (26%) almost certainly reflects referral bias. Many
of the tumors were received in consultation because of
the absence of KIT expression and were subjected to
mutational analyses to substantiate the suspected diag-
nosis of GIST.
TABLE 4. Immunohistochemical Results of KIT, DOG1.1, and CD34 With Lesions in the Differential Diagnosis of GIST (A) and in
Others Tumors (B)
Differential diagnostic tumors (n = 775)
Leiomyosarcoma (n = 334) 1/326 (0.3%) 3/331 (0.9%) 5/334 (1.5%)
Undifferentiated sarcoma (n = 87) 0/79 (0%) 1/87 (1.1%) 9/85 (11%)
Malignant peripheral nerve sheath tumor (n = 86) 0/85 (0%) 0/86 (0%) 11/83 (13%)
Neurofibroma (n = 55) 0/53 (0%) 0/55 (0%) 38/55 (69%)
SS (n = 44) 1/39 (2.5%) 0/44 (0%) 1/44 (2.2%)
Schwannoma (n = 46) 0/44 (0%) 0/45 (0%) 4/44 (9%)
Desmoid fibromatosis (n = 35) 0/35 (0%) 0/32 (0%) 0/31 (0%)
Leiomyoma (n = 22) 0/22 (0%) 0/21 (0%) 0/22 (0%)
Solitary fibrous tumor (n = 21) 0/20 (0%) 0/21 (0%) 12/20 (60%)
Dermatofibrosarcoma protuberans (n = 20) 0/20 (0%) 0/20 (0%) 15/17 (88%)
Dedifferentiated liposarcoma (n = 10) 0/9 (0%) 0/10 (0%) 3/8 (37%)
Desmoplastic melanoma (n = 10) 1/10 (10%) 1/10 (10%) 1/10 (10%)
Inflammatory pseudotumor (n = 5) 0/4 (0%) 0/5 (0%) 0/5 (0%)
Other tumors (n = 160)
Angiosarcoma (n = 14) 0/14 (0%) 1/11 (9%) 7/11 (64%)
Osteosarcoma (n = 14) 0/14 (0%) 0/14 (0%) 0/14 (0%)
Endometrial stroma sarcoma (n = 13) 0/13 (0%) 0/12 (0%) 0/13 (0%)
Rhabdomyosarcoma (n = 13) 0/12 (0%) 0/13 (90%) 1/13 (8%)
Epithelioid hemangioendothelioma (n = 12) 0/12 (0%) 3/12 (25%) 4/12 (33%)
Well-differentiated liposarcoma (n = 11) 0/11 (0%) 0/9 (0%) 0/8 (0%)
Extraskeletal myxoid chondrosarcoma (n = 11) 0/11 (0%) 6/11 (54%) 0/11 (0%)
Low-grade fibromyxoid sarcoma (n = 11) 0/11 (0%) 0/11 (0%) 0/11 (0%)
Fibroadenomas (n = 11) 0/11 (0%) 0/11 (0%) 9/11 (82%)
Myxoid liposarcoma (n = 10) 0/10 (0%) 0/10 (0%) 0/9 (0%)
Ewing/PNET (n = 10) 0/10 (0%) 1/10 (10%) 0/9 (0%)
Clear cell sarcoma (n = 7) 0/7 (0%) 1/7 (14%) 0/7 (0%)
DSRCT (n = 7) 0/6 (0%) 1/7 (14%) 0/7 (0%)
Pleomorphic liposarcoma (n = 3) 0/3 (0%) 0/3 (0%) 0/3 (0%)
Epithelioid sarcoma (n = 3) 0/3 (0%) 0/3 (0%) 1/3 (33%)
Fibrosarcoma (n = 3) 0/3 (0%) 0/3 (0%) 0/3 (0%)
Chondrosarcoma (n = 3) 0/3 (0%) 0/3 (0%) 0/3 (0%)
Alveolar soft part sarcoma (n = 2) 0/2 (0%) 2/2 (100%) 0/2 (0%)
Phyllodes tumor (n = 2) 0/2 (0%) 0/2 (0%) 0/2 (0%)
DSRCT indicates desmoplastic small round cell tumor; PNET, primitive neuroectodermal tumor.
Espinosa et al Am J Surg Pathol
Volume 32, Number 2, February 2008
2008 Lippincott Williams & Wilkins
One of the principal differential diagnoses in GIST
is leiomyosarcoma. In our series of LMS cases used for
this study, there were 3 cases that stained for DOG1.1.
The first case (no. 832) was initially diagnosed as LMS
of the lung; however, additional molecular analysis
performed after DOG1.1 staining was positive showed
a point mutation in exon 18 of PDGFRA (D842V),
confirming a diagnosis of GIST. No additional clinical
history was available and we interpreted this case as either
an extragastrointestinal GIST or a metastasis from
a clinically silent intestinal GIST. The second case
(no. 10057) was initially diagnosed as a LMS metastatic
to liver. Sequence analysis failed to show a mutation in
either the KIT or PDGFRA genes. However, the tumor
was immunopositive for CD34 and KIT and the patient
had a gastric primary. This case was reclassified as a wild-
type GIST. The third case (no. 10180) was considered to
be a true LMS, as no mutation in KIT or PDGFRA was
found and the tumor was from the thigh. As a result,
DOG1.1 was positive in only 1 case of LMS (1/324;
0.3%). DOG1.1 also stained 1 case of desmoplastic
melanoma and 1 case of SS. The diagnosis of SS was
confirmed by fluorescence in situ hybridization and by
staining for TLE1.
The desmoplastic melanoma was
from the skin and express ed both S100 and HMB45.
GIST are believed to originate from the interstitial
cells of Cajal (ICC) or their stem cell precursor.
express KIT and are localized to the myenteric plexus and
in the muscular layers throughout the gastrointestinal
In the nor mal gastrointestinal tract, the pattern of
expression of DOG1 was very similar to KIT, supporting
the idea that DOG1 is also expressed in the ICC.
In conclusion, we have demonstrated that DOG1 is
a very sensitive and specific marker for GIST that works
in paraffin-embedded tissue and is highly expressed in
KIT-mutant and PDGFRA-mutant GIST. The use of
DOG1.1 in clinical practice as either a backup to KIT or
as a part of a panel can allow the identification of more
GIST cases. In our study, 63 patients (DOG1.1+ KIT )
would merit from this approach. These results have an
important clinical implication because most GIST
patients can be benefited from the imatinib treatment.
As a result of its localization in the cell membrane, its
absence in the majority of normal tissue (with the
exception of the myenteric plexus) and the presence in
TABLE 5. Nonsarcoma Neoplasms Positive for DOG1.1 (A)
and KIT (B)
Organ Tumor DOG1.1+
Liver Hepatocellular carcinoma 1/4
Salivary gland Basal cell adenoma 1/1
Adenoid cystic carcinoma 1/7
Lung Adenocarcinoma 1/8
Skin Desmoplastic melanoma 1/10
Organ Tumor KIT+
Breast Ductal carcinoma 1/9
Pancreas Mucinous cystic tumor 1/8
Papillary cystic tumor 1/1
Adrenal gland Neuroblastoma 1/1
Kidney Clear cell carcinoma 1/4
Papillary renal cell carcinoma 1/4
Chromophobe carcinoma 4/4
Oncocytoma 2/2
Transitional cell carcinoma from
the renal pelvis
Neuroblastoma 1/2
Colon Adenoma 2/3
Ovary Dysgerminoma 1/1
Yolk sac tumor 1/1
Urinary bladder Transitional cell carcinoma 3/14
Adenocarcinoma 1/3
Uterus Endometrial carcinoma 2/7
Uterine cervix Adenocarcinoma 1/5
Testis Seminoma 18/21
Yolk sac tumor 1/2
Teratoma 1/2
Mixed germ cell tumor 3/6
Skin Merkel cell carcinoma 3/3
Melanoma (nondesmoplastic) 8/21
Desmoplastic melanoma 1/10
Brain Oligodendroglioma 2/2
Medulloblastoma 2/3
Ependymoma 1/2
Esthesioneuroblastoma 1/1
Duodenum Adenocarcinoma 1/4
Salivary gland Oncocytoma 2/2
Warthin tumor 1/2
Adenoid cystic carcinoma 6/6
Lung Adenocarcinoma 1/8
Squamous cell carcinoma 1/5
Small cell carcinoma 2/3
Low-grade mucoepidermoid
Adenoid cystic carcinoma 1/1
Carcinoid tumor 1/1
Thyroid gland Papillary carcinoma 2/3
Follicular carcinoma 1/1
Follicular adenoma 1/2
Lymph node Diffuse large B-cell lymphoma 1/3
FIGURE 4. DOG1.1 and KIT show similar staining patterns
consistent with ICC staining in the small bowel.
Am J Surg Pathol
Volume 32, Number 2, February 2008 DOG1 is a Sensitive and Specific Marker for GIST
2008 Lippincott Williams & Wilkins 217
most of the GIST, DOG1 may be an additional target in
the treatment of GIST.
Supplementary Data
Supplementary data are available at The PAS
Journal Online (http://tma.stanford.edu/tma_portal/
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Espinosa et al Am J Surg Pathol
Volume 32, Number 2, February 2008
2008 Lippincott Williams & Wilkins
    • "It has been shown that ANO1 contributes to the regulation of renal function, inflammatory and nerve-injury induced hypersensitivity [10]. Amplification and/or overexpression of ANO1 have been frequently observed in gastrointestinal stromal tumors (GISTs) [11][12][13][14][15], breast cancer, head and neck squamous cell carcinoma (HNSCCs) and gastric carcinomas [6, 8, 16] In ANO1-amplified cancer cell lines bearing 11q13 amplification, knockdown of ANO1 inhibited cell proliferation, induced apoptosis, and reduced tumor growth in established cancer xenografts via deactivating EGFR and CAMK signaling. Although a significant correlation has been found between ANO1 expression levels and overall survival (OS) of breast cancer patients [6], the clinical implication of ANO1 in human malignancies remain to be elucidated. "
    [Show abstract] [Hide abstract] ABSTRACT: Objectives: Anoctamin 1 (ANO1) has been found to be overexpressed in esophageal squamous cell carcinoma (ESCC) in our previous study. Herein we showed the clinical relevance of ANO1 alterations with ESCC and esophageal precancerous lesion progression. Results: ANO1 was detected in 38.1% (109/286) and 25.4% (77/303) of tumors in the two cohorts, but in none of morphologically normal operative margin tissues. ANO1 expression was significantly associated with a shorter overall survival (OS), especially in patients with moderately differentiated and stage IIA tumors. In 499 iodine-unstained biopsies from the endoscopic screening cohort in 2005-2007, all the 72 pathologically normal epithelial mucosa presented negative immunostaining, whereas ANO1 expression was observed in 3/11 tumors and 5/231 intraepithelial lesions. 7/8 ANO1-positive cases had developed unfavorable outcomes revealed by endoscopic follow-up in 2012. Analysis of another independent cohort of 148 intraepithelial lesions further confirmed the correlation between ANO1 expression and progression of precancerous lesions. 3/4 intraepithelial lesions with ANO1 expression had developed ESCC within 4-9 years after the initial endoscopic examination. Methods: Immunohistochemistry (IHC) was performed to examine ANO1 expression in surgical ESCC specimens and two independent cohorts of esophageal biopsies from endoscopic screening in high-incidence area of ESCC in northern China. Association between ANO1 expression, clinico-pathologic parameters, and the impact on overall survival was analyzed. Conclusions: Positive ANO1 is a promising biomarker to predict the unfavorable outcome for ESCC patients. More importantly, it can predict disease progression of precancerous lesions.
    Article · Mar 2016
    • "Through different functional assays, the corresponding protein has been identified as a calcium-regulated chloride channel protein (CaCC) with 8 transmembrane domains [2, 5, 6]. DOG1 has been shown to be sensitive and specific when detecting GISTs, although expression of DOG1 in other mesenchymal tumors, such as Ewing's sarcoma, angiosarcoma , leiomyosarcoma, and synovial sarcoma, has also been reported; there have also been occasional cases of DOG1 expression in malignant melanoma and germ cell tumors [1,78910. Additionally, carcinomas of the liver, salivary glands, stomach, colon, esophagus, and lung have shown DOG1 immunoreactivity9101112. "
    [Show abstract] [Hide abstract] ABSTRACT: Aims. DOG1 has proven to be a useful marker of gastrointestinal stromal tumors (GISTs). Recently, DOG1 expression has also been reported in some non-GIST malignant tumors, but the details related to DOG1 expression in breast tissue remain unclear. The aim of this study was to detect the expression of DOG1 in the human breast and to evaluate the feasibility of using DOG1 to discriminate between invasive breast carcinoma and noninvasive breast lesions. Methods and Results. A total of 210 cases, including both invasive and noninvasive breast lesions, were collected to assess DOG1 expression immunohistochemically. DOG1 expression was consistently positive in breast myoepithelial cells (MECs), which was similar to the results obtained for three other MEC markers: calponin, smooth muscle myosin heavy chain (SMMHC), and P63 ( P > 0.05 in all). Importantly, DOG1 was useful in discriminating invasive breast carcinoma from noninvasive breast lesions ( P < 0.05 ). Conclusions. DOG1 is a useful marker of breast MECs, and adding DOG1 to the MEC identification panel will provide more sophisticated information when diagnosing uncertain cases in the breast.
    Full-text · Article · Mar 2016
    • "Structural analysis predicted that FLJ10261 protein possessed eight TM domains possibly functioning as an ion transporter [52]. Since the FLJ10261 gene was found to be uniformly expressed with a high level of gastrointestinal stromal tumors (GISTs) thereby being named DOG1 (discovered on GIST1) [111] , ANO1/DOG1 has been emerging as a potential diagnostic marker for GIST [36, 48, 62, 71, 77]. Although ANO1 is found to be widely expressed in various tissues including the secretory epithelium [49], Ano1 has been found to be upregulated in numerous carcinomas including head and neck squamous cell carcinoma (HNSCC) [5, 30, 34], lung cancer [50], breast cancer [13, 112] , colorectal can- cer [100], pancreatic ductal adenocarcinoma [92] , gastrointestinal stromal tumor [111] , esophageal squamous cell carcino- ma [51, 97], chondroblastoma [2] , salivary gland tumor (designated as ORAOV2, oral cancer overexpressed 2) [22], oral cancer (designated as TAOS1, tumor-amplified and overexpressed sequence 1) [42, 63], uterine leiomyosarcoma [90], glioma [65], and prostate cancer [66] . "
    [Show abstract] [Hide abstract] ABSTRACT: Ca2+-activated Cl− channels (CaCCs) are a class of Cl− channels activated by intracellular Ca2+ that are known to mediate numerous physiological functions. In 2008, the molecular identity of CaCCs was found to be anoctamin 1 (ANO1/TMEM16A). Its roles have been studied in electrophysiological, histological, and genetic aspects. ANO1 is known to mediate Cl− secretion in secretory epithelia such as airways, salivary glands, intestines, renal tubules, and sweat glands. ANO1 is a heat sensor activated by noxious heat in somatosensory neurons and mediates acute pain sensation as well as chronic pain. ANO1 is also observed in vascular as well as airway smooth muscles, controlling vascular tone as well as airway hypersensitivity. ANO1 is upregulated in numerous types of cancers and thus thought to be involved in tumorigenesis. ANO1 is also found in proliferating cells. In addition to ANO1, involvement of its paralogs in pathophysiological conditions was also reported. ANO2 is involved in olfaction, whereas ANO6 works as a scramblase whose mutation causes a rare bleeding disorder, the Scott syndrome. ANO5 is associated with muscle and bone diseases. Recently, an X-ray crystal structure of a fungal TMEM16 was reported, which explains a precise molecular gating mechanism as well as ion conduction or phospholipid transport across the plasma membrane.
    Full-text · Article · Jan 2016
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