The Anti-tumor Effect of a Small Polypeptide From Coriolus versicolor (SPCV)

The mushroom has historically attracted attention as a health-oriented food not only in China and Japan but also world wide. The anti-tumor effect of various kinds of mushroom components have been noted during the last decade and much recent research in this field involves the development of new analytical techniques to study these pharmacologically interesting materials (1,2,3,4,5,6). The most potent strain examined was Coriolus versicolor in which PSK (polysaccharide Krestin) was extracted from Basidiomycetes reported from Japan in 1965 (7,8) and PSP (polysaccharide peptide) from Cov-1 (Yun Zhi) reported from China in 1984 (9). Many experimental studies and clinical investigations of PSK (1,10) and PSP (9,11) in relation to their anti-tumor effect and especially for their potential use in cancer immunotherapy have been reported. it was found that the anti-tumor effect of PSP was more potent than that of PSK (12). in vitro experiments showed that PSP inhibited the proliferation of P388 leukemia cells and Ehrlich ascites cells; it also inhibited the proliferation of some human tumor cell lines including SCG-7901, SPC, and SLY (4). In vivo experiments showed that PSP inhibited the growth of murine sarcoma 180 in tumor bearing mice (13). The immunopotentiating effect of PSP was also noted. and it was seen that PSP increased the thymus weight and the serum C3 and IgG content of tumor bearing mice (14). Furthermore. PSP promoted lymphocyte proliferation and increased the production of IL-2 and interferon (INF) (15). A clinical study at the Shanghai Medical University involving 151 cases of various kinds of cancer patients who were treated with PSP. found noticeable and remarkable anti-cancer effect without toxicity to the body (11). Furthermore, PSP was of notable value in maintaining or even raising white blood cell counts; it also lessened the side effects of chemotherapy and radiotherapy, increased appetite, and relieved pain in cancer patients (11). Since the PSP used in these studies was in crude extracts form, further purifications of PSP are needed. The mechanism of the anti-tumor effect of PSP is not clear and needs further investigation.

In our laboratory a new small polypeptide was isolated from the crude PSP by high performance liquid chromatography (HPLC) and capillary isoelectrophoresis focusing (CIEF). This biomolecule was proved to have a molecular weight of 10K (Mr) named Small Polypeptide of Coriolus Versicolor (SPCV). In our present studies we found that SPCV possesses more potent antitumor effect than the crude extraction of PSP in which a polysaccharide peptide with high molecular weight about l00K (Mr) from PSP was earlier reported (16).

Materials and Methods

Purification of PSP 

Cultured polysaccharides peptide (PSP) extracted from Coriolus versicolor of mycelia Cov-1 was kindly supplied by the Mushroom Research Laboratory of Shanghai Teachers University. This water soluble brown powder was boiled, centrifuged and filtered. It was purified by gel filtration chromatograph. HPLC and CIEF. A small polypeptide was obtained from the above purification and assayed for its anti-tumor activity both in vivo and in vitro experiments using gel filtration column chromatography. The aqueous extract of PSP was first purified by Sephacryl S-300 column chromatograph (Pharmacia Fine Chemicals, Sweden) at a rate of 3 ml/l0 mm in 10mM sodium phosphate buffer, pH 7.2. Eluants were collected with an automatic fractioning collector. Contents of each fraction were measured for their optical density at 280 nm. This wave length corresponds to the light absorption of peptide linkage.

Acknowledgments

We wish to thank Dr. Ballard for her help in HPLC analysis. and Dr. Hu Ka for her technical assistance. The authors also wish to thank Bio-Rad Company for the CIEF analysis. This work is supported by grants from CRCG and L.W.T. research grant committee, University of Hong Kong and from Windsor Health Product Co.. Hong Kong.

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