Increased concentration of sialidases by HeLa cells might influence the cytotoxic ability of NK cells.
OBJECTIVE
Cancer cells reportedly have the ability to escape from the immune system, mainly from natural killer (NK) cells. Although the real mechanisms are complicated, some inhibitors that are secreted from the cancer cells might play an important role. This study's aim was to investigate the potential mediator released by cancer cells (HeLa) that contributes to the decreased cytotoxicity of NK cells.


METHODS
An NK-HeLa coculture system was used to test the hypothesis that the presence of the potential mediator from cancer cells contributes to the decreased cytotoxicity of NK cells.


RESULTS
After coculturing with HeLa cancer cells, the cytotoxicity of NK cells was decreased. When the coculture medium and culture medium containing commercialized sialidase were used to culture NK cells, the cytotoxicity of the NK cells was also inhibited. However, cytotoxicity was partially restored by a sialidase inhibitor (DANA). Western blot analysis of the HeLa cells after coculturing with NK cells demonstrated increased Neu2 and Neu3 expression in HeLa cells.


CONCLUSIONS
The finding that Neu2 and Neu3 expression in cancer cells might be involved in the impaired function of NK cells, which could be restored by a sialidase inhibitor, provides a new concept that could be applied to the management of cancer.
Department of Obstetrics and Gynecology, National Yang-Ming University School of Medicine, Taipei, Taiwan.
Wen-Chi
WC
Lee
Wen-Ling
WL
Lee
Wen-Yuann
WY
Shyong
Ling-Wei
LW
Yang
Min-Chun
MC
Ko
Bor-Ching
BC
Sheu
Shie-Liang Edmond
SL
Hsieh
Peng-Hui
PH
Wang
D018920:Coculture Techniques; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D006367:HeLa Cells / Q000201:enzymology* / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology*; D009439:Neuraminidase / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D013400:Sugar Acids / Q000494:pharmacology
C577845:5-acetamido-2,6-anhydro-2,3-dehydro-3,5-dideoxy-glycerogalactononanoic acid; D013400:Sugar Acids; C403285:NEU2 protein, human; C465436:Neu3 protein, human; D009439:Neuraminidase