Augmentation of Cytolytic Activity in Murine Natural Killer Cells and Inhibition of Tumor Growth by the Ethanol Fraction of Oyster Extract

A reduced number and/or reduced activity of natural killer (NK) cells, which are important for defense against a variety of cancers and viral infections, occur under various stress conditions and in patients with various diseases. In this article, we report that the 30% to 50% ethanol precipitate of...

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Published in:	Integrative cancer therapies Vol. 17; no. 1; pp. 31 - 40
Main Authors:	Sakaguchi, Kaito, Zhong, Ming, Kawai, Saeko, Shimizu, Yoshio, Gohda, Eiichi
Format:	Journal Article
Language:	English
Published:	Los Angeles, CA SAGE Publications 01-03-2018 SAGE PUBLICATIONS, INC SAGE Publishing
Subjects:	Animals Cell activation Cell proliferation Cytolytic activity Cytotoxicity, Immunologic - immunology Endopeptidase K Ethanol Female Killer Cells, Natural - immunology Melanoma Melanoma, Experimental - immunology Melanoma, Experimental - therapy Mice Mice, Inbred C57BL Molecular weight Natural killer cells Oligonucleotides Ostreidae Polymers Proteinase Spleen Spleen - cytology Tissue Extracts - immunology Tissue Extracts - pharmacology Tumor cells oyster melanoma activation NK cell antitumor effect
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Summary:	A reduced number and/or reduced activity of natural killer (NK) cells, which are important for defense against a variety of cancers and viral infections, occur under various stress conditions and in patients with various diseases. In this article, we report that the 30% to 50% ethanol precipitate of oyster extract (EPOE50) dose-dependently enhanced the activity of mouse spleen NK cells in vitro and in vivo. The activity of EPOE50 was eluted with a molecular weight of about 2000 by gel filtration and was inactivated by periodate but not by proteinase K. The activity of highly purified NK cells was also augmented by EPOE50 but not by oligodeoxyribonucleotide 1585, which mimics bacterial DNA. Administration of EPOE50 to mice stimulated splenic NK cell activity without a change in splenic NK cell populations. Although the proliferation of B16 tumor cells in vitro was slightly stimulated by EPOE50, the growth of B16 melanoma in vivo was dose-dependently suppressed by administration of EPOE50. Taken together, our results indicate that EPOE50 augmented NK cell activity and that its administration to mice inhibited tumor growth presumably through the activation of NK cells and also suggest that the active substance is a sugar-containing oligomer or polymer and is not of bacterial origin.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1534-7354 1552-695X
DOI:	10.1177/1534735416681640