Reversible inhibition of proliferation of epithelial cell lines by Agaricus bisporus (edible mushroom) lectin

• Published in: Cancer research (Chicago, Ill.) Vol. 53; no. 19; pp. 4627 - 4632
• Main Authors: LUGANG YU, FERNIG, D. G, SMITH, J. A, MILTON, J. D, RHODES, J. M
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.10.1993
• Subjects: Adenocarcinoma; Adult; Agaricus; Aged; Animals; Antineoplastic agents; Arachis; Binding Sites; Biological and medical sciences; Breast Neoplasms; Carbohydrate Sequence; Cell Division - drug effects; Cell Membrane - metabolism; Cell Survival - drug effects; Colonic Neoplasms; Disaccharides; DNA, Neoplasm - biosynthesis; DNA, Neoplasm - drug effects; Dose-Response Relationship, Drug; Epidermal Growth Factor - pharmacology; Epithelial Cells; Epithelium - drug effects; Female; General aspects; Humans; Lectins - metabolism; Lectins - pharmacology; Male; Mammary Glands, Animal; Medical sciences; Molecular Sequence Data; Peanut Agglutinin; Pharmacology. Drug treatments; Plant Lectins; Rats; Thymidine - metabolism; Tumor Cells, Cultured; Human; Cell proliferation; Agaricus bisporus; Lectin; Carbohydrate antigen; Tumor associated antigen; Basidiomycetes; Glycoproteins; In vitro; Cell surface; Biological activity; Fungi; Established cell line; Plant origin; Epithelial cell; Inhibition; Tumor cell; Thallophyta
• ISSN: 0008-5472

Galactosyl beta-1,3-N-acetyl galactosamine (Gal beta-1,3-GalNAc) (Thomsen Friedenreich antigen), the Class I core sequence in O-linked oligosaccharide chains, behaves as an oncofetal antigen showing increased expression in many epithelial malignancies. Previous work has shown that peanut agglutinin (PNA), a lectin that binds Gal beta-1,3-GalNAc, stimulates proliferation in HT-29 (human colon cancer) cells and normal human colonic epithelium and this implies that cell surface glycoproteins which express Gal beta-1,3-GalNAc may play an important role in the regulation of epithelial cell proliferation. We have now studied the effect on epithelial cells of another dietary Gal beta-1,3-GalNAc-binding lectin, the edible mushroom Agaricus bisporus lectin (ABL). This differs from PNA in its ability to bind also to sialylated Gal beta-1,3-GalNAc. In contrast to PNA, ABL (25 micrograms/ml) inhibited incorporation of [3H]-thymidine into DNA of HT29 colon cancer cells by 87% (95% confidence limit, 85-89%), Caco-2 colon cancer cells by 16% (95% confidence limit, 12-20%), MCF-7 breast cancer cells by 50% (95% confidence limit, 47-52%), and Rama-27 rat mammary fibroblasts by 55% (95% confidence limit, 51-60%) when these cells were grown for 24 h in serum-free medium. When assessed by cell count, similar inhibition of proliferation of HT29 cells by ABL was found. In the presence of 2% fetal calf serum (which contains the ABL-binding glycoprotein fetuin), the inhibitory effect of ABL on cell proliferation was still demonstrable but at increased ABL concentration (60 micrograms/ml for 49% inhibition). Ten micrograms/ml ABL completely abolished the stimulatory effect on [3H]thymidine incorporation of epidermal growth factor (100 pg/ml) and PNA (25 micrograms/ml) and markedly inhibited the stimulatory effect of insulin (50 ng/ml). ABL (0.2 mg/ml) caused no cytotoxicity to HT29, MCF-7, and Rama-27 cells as measured by trypan blue exclusion, and inhibition of proliferation in HT29 cells caused by 50 micrograms/ml ABL was reversible after removal of the lectin. Binding studies with 125I-labeled ABL suggested a single class of binding site with an apparent Kd value of (4.12 +/- 0.29) x 10(-7) M with (3.6 +/- 0.3) x 10(7) binding sites/cell. A. bisporus lectin is a reversible noncytotoxic inhibitor of epithelial cell proliferation which deserves study as a potential agent for cancer therapy.