Soluble branched (1,4)-beta-D-glucans from Acetobacter species enhance antitumor activities against MHC class I-negative and -positive malignant melanoma through augmented NK activity and cytotoxic T-cell response.

Abstract

We previously found that an extracellular polysaccharide, AC-1, produced by Acetobacter polysaccharogenes composed of (1,4)-beta-D-glucan with branches of glucosyl residues showed a strong activity to induce production of interleukin (IL)-12 p40 and tumor necrosis factor-alpha by macrophage cell lines in vitro via Toll-like receptor-4 signaling. In the present study, we examined the effects of oral administration of AC-1 on protection against 2 types of murine B16 melanoma lines, major histocompatibility complex (MHC) class I-negative B16L and MHC class I gene-transfected B16K(b) cells. Mice were inoculated subcutaneously with B16L or B16K(b) cells on day 0 and administrated intragastrically with AC-1 or PBS once every 5 days from 1 day before tumor inoculation. The tumor growth was severely retarded in AC-1-treated mice after subcutaneous inoculation with B16L or B16K(b) cells. The AC-1-treated mice showed augmented natural killer (NK) cell activity against B16L cells, and in vivo depletion of NK cells by antiasialoGM1 antibody (Ab) treatment abrogated the antitumor activity in AC-1-treated mice. On the other hand, AC-1-treated mice inoculated with B16K(b) cells developed a significantly higher level of cytotoxic T-lymphocyte response against B16K(b) cells, and in vivo depletion of CD8(+) T cells by anti-CD8 mAb treatment abrogated the antitumor activity. Thus, AC-1 augmented antitumor activity against different tumors via augmentation of different antitumor mechanisms. These results suggest a possible prophylactic application of AC-1 for human neoplasms irrespective of expression levels of their MHC class I molecules.

• Authors: Yoriyuki Kamiryo, Toshiki Yajima, Kimika Saito, Hitoshi Nishimura, Takashi Fushimi, Yoshifumi Ohshima, Yoshinori Tsukamoto, Seiji Naito, Yasunobu Yoshikai
• Journal: International journal of cancer (Int J Cancer) Vol. 115 Issue 5 Pg. 769-76 (Jul 10 2005) ISSN: 0020-7136 [Print] United States
• PMID: 15729692 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: (c) 2005 Wiley-Liss, Inc.

Chemical References

• Glucans
• HLA Antigens

Topics

• Acetobacter (chemistry)
• Administration, Oral
• Animals
• Disease Models, Animal
• Female
• Genes, MHC Class I
• Glucans (pharmacology)
• HLA Antigens (biosynthesis)
• Humans
• Killer Cells, Natural (immunology)
• Male
• Melanoma (pathology)
• Mice
• Mice, Inbred C57BL
• Skin Neoplasms (pathology)
• T-Lymphocytes, Cytotoxic (immunology)
• Tumor Cells, Cultured