(CNA file photo)

Taipei, Aug. 30 (CNA) Scientists at Academia Sinica have cracked the mystery of how the polysaccharides in the reishi mushroom act to activate the human immune system and fight against cancer, and have shared their discovery with the world.

A research team headed by Academia Sinica President Chi-Huey Wong and assistant research fellow Wu Chung-yi has proven that a crude extract of fucose-containing polysaccharides from reishi mushrooms, named F3, can induce antibodies to recognize tumor-associated carbohydrate antigens on cancer cells and kill them.

According to Academia Sinica, Taiwan's top academic research institute, the research on reishi polysaccharides' cancer-fighting effects was started by a group headed by National Yang-Ming University professor Hsu Hsieh-yeh, which injected F3 into mice with lung cancer and discovered that the extract could slow tumor growth, although it did not know how the mechanism works.

Thanks to a glycan array -- a sample-screening method -- designed by the Wong-Wu team, it was found that the sera from mice immunized with F3 contain the antibodies that recognize the tumor antigens known as Globo H, as well as related structures.

Moreover, the research team also found that inhibition of tumor growth is directly related to the amount of these types of antibodies. In other words, the larger the amount of Globo H-recognizing anitibodies, the smaller the tumor, Academia Sinica said.

With the finding, the team separated F3 into a fucose-enriched fraction called FMS for immunization and found that FMS can induce even more anti-Globo H antibodies and thus, more effectively inhibit tumor growth.

The study further demonstrated that the fucose residue is the key to the reishi mushroom's cancer-fighting ability, proven by the finding that the cancer-fighting activity was reduced dramatically when the fucose residue was removed.

With assistance from other research teams, the effective structures of the fucose-containing saccharides were elucidated. This research thereafter established the molecular mechanism of reishi polysaccharides with regard to their cancer-fighting activity, the institute said.

The research results were published in the current issue of the U.S.'s Proceedings of the National Academy of Sciences (PNAS) journal, under the title: "Immunization of fucose-containing polysaccharides from reishi mushroom induces antibodies to tumor-associated Globo H-series epitopes."

The first authors of the paper are named as Liao Shih-fen, a PhD student at the Institute of Biochemical Sciences of National Taiwan University, and Liang Chi-hui, who is conducting post-doctoral research at the Genomics Research Center of Academia Sinica.

(By Chen Chih-chung and Elizabeth Hsu)
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