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Tumor cell alpha-N-acetylgalactosaminidase activity and its involvement in GcMAF-related macrophage activation (Abstract)

Alpha-N-acetyl galactosaminidase (alpha-NaGalase) has been reported to accumulate in serum of cancer patients and be responsible for deglycosylation of Gc protein, which is a precursor of GcMAF-mediated macrophage activation cascade, finally leading to immunosuppression in advanced cancer patients.

We studied the biochemical characterization of alpha-NaGalase from several human tumor cell lines. We also examined its effect on the potency of GcMAF to activate mouse peritoneal macrophage to produce superoxide in GcMAF-mediated macrophage activation cascade. The specific activity of alpha-NaGalases from human colon tumor cell line HCT116, human hepatoma cell line HepG2, and normal human liver cells (Chang liver cell line) were evaluated using two types of substrates; GalNAc-alpha-PNP (exo-type substrate) and Gal-beta-GalNAc-alpha-PNP (endo-type substrate).

Tumor-derived alpha-NaGalase having higher activity than normal alpha-NaGalase, had higher substrate specificity to the exo-type substrate than to the endo-type substrate, and still maintained its activity at pH 7. GcMAF enhance superoxide production in mouse macrophage, and pre-treatment of GcMAF with tumor cell lysate reduce the activity.

We conclude that tumor-derived alpha-NaGalase is different in biochemical characterization compared to normal alpha-NaGalase from normal Chang liver cells. In addition, tumor cell-derived alpha-NaGalase decreases the potency of GcMAF on macrophage activation.

Article Outline

1. Introduction

2. Materials and methods

2.1. Materials
2.2. Cell culture and sample preparation
2.3. Alpha-N-acetyl-galactosaminidase activity assay
2.4. Isolation and culture of mouse peritoneal macrophages
2.5. Superoxide generation assay
2.6. GcMAF preparation

3. Results

3.1. Alpha-NaGalase activities in human tumor cell lines
3.2. GcMAF-mediated macrophage activation cascade and effect of alpha-NaGalase

4. Discussion

Acknowledgements

References

Source: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VNH-44YF922-2&_user=10&_coverDate=05%2F31%2F2002&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=bf5f235de743ce09345a565275d4df12

Author Keywords: Alpha-N-acetylgalactosaminidase; Gal-beta-GalNAc-alpha-PNP; GalNAc-alpha-PNP; GcMAF-mediated macrophage activation cascade; Gc protein-derived macrophage activating factor (GcMAF); Mouse peritoneal macrophage; Superoxide; Tumor cells

Erratum to “Tumor cell alpha-N-acetylgalactosaminidase activity and its involvement in GcMAF-related macrophage activation”: [Comp. Biochem. Physiol. A 132 (2002) 1–8]
Comparative Biochemistry and Physiology – Part A: Molecular & Integrative Physiology, Volume 134, Issue 2, February 2003, Page 481,
Saharuddin B. Mohamad, Hideko Nagasawa, Yoshihiro Uto, Hitoshi Hori
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