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International Journal of Medicinal Mushrooms

ISSN for PRINT: 1521-9437

Institutional price:	$538.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2000, Volume2

84 pages

Issue price - $128.00

Antitumor Activity of Oral Administration of Mycovirus Extract from Lentinus edodes (Berk.) Sing. (Agaricomycetideae) on Murine Lymphoma

Sudhir C. Kumar
Department of Internal Medicine, Illinois Masonic Medical Center, 836 West Wellington Avenue, Chicago, IL 60657, USA

Mah-Lee Ng
Department of Microbiology, Faculty of Medicine, National University of Singapore, 5 Science Drive 2, Singapore 117597

ABSTRACT

The present study evaluated the antitumor activity of polyethylene glycol (PEG)-concentrated double-stranded RNA mycovirus, present abundantly in fresh 2-day-old buds of Lentinus edodes (shiitake mushroom). K36 cell-line induced murine lymphoma in male AKR mice was the tumor-model used. The difference in antitumor activity by three types of intervention in relation to leukemia cell inoculation was assessed. The three interventions were: prefeeding with mycovirus extract before K36 cell inoculation, simultaneously feeding of extract with K36 cell inoculation and administering the extract after tumors were induced. Tumors obtained 14 d after leukemia cell inoculation were investigated in detail. Prefeeding with mycovirus extract conferred the best antitumor activity with a tumor inhibition rate of 80.7% (p < 0.001). Simultaneous feeding and administering extract after tumors were induced were also effective with tumor regression rates of 73.8% (p < 0.001) and 67.6% (p < 0.001), respectively. In addition, the effective dose of mycovirus extract caused only a negligible body-weight reduction of 0.63% (p = 0.866) without any toxic effects in mice. Electron microscopy revealed apoptotic cells in all three regimens. These findings were confirmed by confocal microscopy on TUNEL-stained lymphoma sections, a hallmark of apoptosis. Interestingly, electron microscopy also revealed abundant defective tumor retrovirus in the prefed regimen and lesser in the other two regimens. Cytokines interferon-γ and tumor necrosis factor-α in serum from healthy mice was assayed after oral administration of the extract. These surrogate markers of immunomodulation were significantly elevated (p = 0.004 and p = 0.025, respectively). This proved the formulated hypothesis that immunomodulation by mycovirus extract contributed to the observed antitumor activity and production of defective tumor retrovirus.