[Preliminary study on the antitumor immuno-protective mechanism of beta-elemene].

OBJECTIVE: To study the antitumor effects and their molecular mechanism of beta-elemene, which is one of the effective monomers of Oleum Curcuma aromatica, a Chinese anticancer medicament.
METHODS: The expression of membrane protein HSP70 on H22 cells treated with beta-elemene or mitomycin C(MMC) was analysed by immunofluorescence and flow cytometric techniques and the antitumor effects of the treated H22 cells was examined in C57BL/6 mice.
RESULTS: The expression rate or intensity of membrane protein HSP70 of H22 cells treated with beta-elemene, and those treated with MMC was both significantly higher than that of the untreated H22 cells (P < 0.001). Increase in HSP70 expression was most marked when H22 cells were treated with beta-elemene and MMC in combination, with an expression rate of 95.1%. Heat shock treatment of the H22 cells combined with other stress-inducing factors could further increase the HSP70 expression intensity. Specific antitumor immunity could be elicited in C57BL/6 mice immunized with beta-elemene-treated H22 cells, and the effect could be partially blocked by anti-HSP70 mAb. In mice immunized with beta-elemene-treated H22 cells, tumor developed in 3 of 11 mice, while in the immunized mice given anti-HSP70 mAb, 5 out of 10 mice developed tumor, and all of the control mice developed tumor. The average tumor weight (g) on day 28 after challenge with untreated H22 cells was 0.17 +/- 0.33, 0.66 +/- 0.77 and 1.11 +/- 0.58 in the three groups of mice, respectively.
CONCLUSION: beta-elemene increases tumor cell immunogenicity by inducing, at least in part, elevated expression of heat shock protein 70 on tumor cell surface.