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Folate receptor of human mammary adenocarcinoma
Author(s) -
Holm JAN,
Hansen STEEN I.,
HØIerMadsen MIMI,
SØNdergaard KNUD,
Bzorek MICHAEL
Publication year - 1994
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1699-0463.1994.tb04892.x
Subject(s) - radioligand , immunostaining , radioligand assay , chemistry , mammary gland , receptor , folate receptor , mammary tumor , dissociation constant , biochemistry , microbiology and biotechnology , biology , endocrinology , medicine , immunohistochemistry , immunology , cancer , cancer cell , breast cancer
Binding of 3 H‐folate to human mammary tumor homogenate was of a high‐affinity type (K= 10 10 M −1 ) and displayed apparent positive cooperativity. Radioligand dissociation was slow at pH 7.4, but rapid at pH 3.5. As compared to methotrexate, 5‐formyltetrahydrofolate acted as a strong inhibitor of radioligand binding. Gel chromatography of radioligand‐labeled homogenate of tumor tissue revealed three peaks: a small 110 kDa peak and two major peaks of folate‐binding activity (M r ∼ 25 kDa and M r ∼ 100 kDa). Mammary tumor tissue showed immunostaining with rabbit antibodies against human milk folate binder. A parallel elevation in the concentrations of folate‐binding protein and triglyceride in tumor tissue as compared to normal tissue adjacent to the tumor was compatible with the localization of folate‐binding protein in the triglyceride‐rich fraction of mammary gland homogenate.