CSPG4 protein as a new target for the antibody-based immunotherapy of triple-negative breast cancer.
BACKGROUND
The cell surface proteoglycan, chondroitin sulfate proteoglycan 4 (CSPG4), is a potential target for monoclonal antibody (mAb)-based immunotherapy for many types of cancer. The lack of effective therapy for triple-negative breast cancer (TNBC) prompted us to examine whether CSPG4 is expressed in TNBC and can be targeted with CSPG4-specific mAb.


METHODS
CSPG4 protein expression was assessed in 44 primary TNBC lesions, in TNBC cell lines HS578T, MDA-MB-231, MDA-MB-435, and SUM149, and in tumor cells in pleural effusions from 12 metastatic breast cancer patients. The effect of CSPG4-specific mAb 225.28 on growth, adhesion, and migration of TNBC cells was tested in vitro. The ability of mAb 225.28 to induce regression of tumor metastases (n = 7 mice) and to inhibit spontaneous metastasis and tumor recurrence (n = 12 mice per group) was tested in breast cancer models in mice. The mechanisms responsible for the antitumor effect of mAb 225.28 were also investigated in the cell lines and in the mouse models. All statistical tests were two-sided.


RESULTS
CSPG4 protein was preferentially expressed in 32 of the 44 (72.7%) primary TNBC lesions tested, in TNBC cell lines, and in tumor cells in pleural effusions from 12 metastatic breast cancer patients. CSPG4-specific mAb 225.28 statistically significantly inhibited growth, adhesion, and migration of TNBC cells in vitro. mAb 225.28 induced 73.1% regression of tumor metastasis in a TNBC cell-derived experimental lung metastasis model (mAb 225.28 vs control, mean area of metastatic nodules = 44590.8 vs 165950.8 μm(2); difference of mean = 121360.0 μm(2), 95% confidence interval = 91010.7 to 151709.4 μm(2); P < .001). Additionally, mAb 225.28 statistically significantly reduced spontaneous lung metastases and tumor recurrences in an orthotopic xenograft mouse model. The mechanisms responsible for antitumor effect included increased apoptosis and reduced mitotic activity in tumor cells, decreased blood vessel density in the tumor microenvironment, and reduced activation of signaling pathways involved in cell survival, proliferation and metastasis.


CONCLUSIONS
This study identified CSPG4 as a new target for TNBC. The antitumor activity of CSPG4-specific mAb was mediated by multiple mechanisms, including the inhibition of signaling pathways crucial for TNBC cell survival, proliferation, and metastasis.
Wang
Xinhui
X
University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.
Osada
Takuya
T
Wang
Yangyang
Y
Yu
Ling
L
Sakakura
Koichi
K
Katayama
Akihiro
A
McCarthy
James B
JB
Brufsky
Adam
A
Chivukula
Mamatha
M
Khoury
Thaer
T
Hsu
David S
DS
Barry
William T
WT
Lyerly
H Kim
HK
Clay
Timothy M
TM
Ferrone
Soldano
S
D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D011508:Chondroitin Sulfate Proteoglycans / Q000187:drug effects* / Q000276:immunology*; D015986:Confounding Factors, Epidemiologic; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007167:Immunotherapy / Q000379:methods*; D008175:Lung Neoplasms / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D008545:Melanoma / Q000188:drug therapy / Q000276:immunology; D008565:Membrane Proteins / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D010996:Pleural Effusion / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D014183:Transplantation, Heterologous; D000099216:Chondroitin Sulfate Proteoglycan 4
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D011508:Chondroitin Sulfate Proteoglycans; D008565:Membrane Proteins; C101390:CSPG4 protein, human; D000099216:Chondroitin Sulfate Proteoglycan 4