Effect of simulated microgravity on murine melanoma cells: Altered tumor cell and tumorigenicity
2005
Taga, M.(Kitasato Junior Coll. of Health and Hygiene Sciences, Minami-Uonuma, Niigata (Japan)) | Kanouchi, H. | Oka, T.
Short-term or long-term space flight induces numerous biological stressors that affect several human physiological systems. The physical factors and their physiologic stressors cause several system dysfunctions. The incidence of tumor growth and carcinogenesis in microgravity is yet unknown. Hence, we investigated the effects of simulated microgravity on tumor growth and tumorigenicity using ground-based in vitro and in vivo models. Murine B16-FIO melanoma cells were cultured in a rotating wall vessel bioreactor (BIO), designed by NASA to simulate some aspects of microgravity, and a tissue culture flask (FL). We then measured cell growth, melanin production and apoptosis. After 48 hours of culture in FL and BIO, cells were inoculated subcutaneously in C57BL/6 mice syngeneic hosts for B16-FIO tumor cells. The growth of BIO cells decreased to 50% (p0.01), and doubling time increased. Melanin production, a marker of differentiation, increased to 150% (p0.05)' in BIO. Flow cytometry analysis showed that there was increase in the percentage of apoptotic cells in the BIO when compared with that in the FL. When BIO cultured melanoma cells were inoculated subcutaneously in mice there was significant increase in tumorigenicity (p.001) as compared to FL cells. Our results indicate that simulated microgravity may have altered the tumor cell characteristics and enhanced the invasive property. It is possible that the microgravity analog culture environment may have selected highly tumorigenic cells for survival despite the decreased overall growth in the microgravity analog.
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