Novel anti-filamin-A antibody detects a secreted variant of filamin-A in plasma from patients with breast carcinoma and high-grade astrocytoma.
Identification of tumor-derived proteins in the circulation may allow for early detection of cancer and evaluation of therapeutic responses. To identify circulating tumor-derived proteins, mice were immunized with concentrated culture medium conditioned by human breast cancer cells. Antibodies generated by hybridomas were screened against conditioned media from both normal epithelial cells and tumor cells. Antibody selectively reacting with tumor cell-conditioned media was further characterized. This led to the development of a monoclonal antibody (Alper-p280) that reacts with a newly identified 280-kDa secreted variant of human filamin-A. Circulating filamin-A was detected in patient plasma samples using Alper-p280 in an ELISA assay. Human plasma samples from 134 patients with brain, breast, or ovarian cancer, 15 patients with active arthritis, and 76 healthy controls were analyzed. Filamin-A protein levels in human cell lines and tissues were analyzed by western blotting, immunohistochemistry, and electron and confocal microscopy. Circulating filamin-A was detected in the plasma of 109 of 143 patients with breast cancer and primary brain tumors. Plasma levels of filamin-A showed 89.5% sensitivity (95% confidence interval [CI] = 0.67% to 0.99%) and 97.8% specificity (95% CI = 0.88% to 0.99%) for glioblastoma at a cut-off of 21.0 ng/mL. Plasma levels of filamin-A (>36.0 ng/mL) had 96.7% sensitivity (95% CI = 0.80% to 0.99%) and 67.8% specificity (95% CI = 0.54% to 0.79%) for metastatic breast cancer. Filamin-A levels were increased in malignant breast or brain tissues, but not in normal control tissues. Filamin-A localized to lysosomes in MDA.MB.231 breast cancer cells, but not in normal human mammary epithelial cells, suggesting that filamin-A may undergo cancer-specific processing. Plasma filamin-A appears to be a specific and sensitive marker for patients with high-grade astrocytoma or metastatic breast cancer. Additional novel cancer biomarkers have been identified and are being developed alongside Alper-p280 for use in diagnosis of breast carcinoma and high-grade astrocytoma, and for use in the evaluation of therapeutic responses.
Alper
Ozge
O
Alper Biotech, LLC, Rockville, Maryland, USA. oalper@alperbiotech.com
Stetler-Stevenson
William G
WG
Harris
Lyndsay N
LN
Leitner
Wolfgang W
WW
Ozdemirli
Metin
M
Hartmann
Dan
D
Raffeld
Mark
M
Abu-Asab
Mones
M
Byers
Stephen
S
Zhuang
Zhengping
Z
Oldfield
Edward H
EH
Tong
Yanhe
Y
Bergmann-Leitner
Elke
E
Criss
Wayne E
WE
Nagasaki
Koichi
K
Mok
Samuel C
SC
Cramer
Daniel W
DW
Karaveli
F Seyda
FS
Goldbach-Mansky
Raphaela
R
Leo
Paul
P
Stromberg
Kurt
K
Weil
Robert J
RJ
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001168:Arthritis / Q000097:blood / Q000276:immunology / Q000473:pathology; D001254:Astrocytoma / Q000097:blood* / Q000276:immunology / Q000473:pathology; D014408:Biomarkers, Tumor / Q000097:blood; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001940:Breast / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000097:blood* / Q000276:immunology / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000097:blood* / Q000276:immunology / Q000556:secondary*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000097:blood / Q000276:immunology / Q000556:secondary; D018275:Carcinoma, Lobular / Q000097:blood / Q000276:immunology / Q000556:secondary; D016022:Case-Control Studies; D003285:Contractile Proteins / Q000097:blood* / Q000276:immunology*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D064448:Filamins; D006801:Humans; D007114:Immunization; D007124:Immunoenzyme Techniques; D008207:Lymphatic Metastasis; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008840:Microfilament Proteins / Q000097:blood* / Q000276:immunology*; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D010051:Ovarian Neoplasms / Q000097:blood / Q000276:immunology / Q000473:pathology; D011379:Prognosis; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D003285:Contractile Proteins; D017077:Culture Media, Conditioned; D064448:Filamins; D008840:Microfilament Proteins