Specific cytotoxicity of natural killer cells against hepatocellular carcinoma and potential mechanism / 军事医学

ABSTRACT

Objective To evaluate the cytotoxicity of natural killer(NK)-92 cell lines against various human hepatocellular carcinoma cells(HCCs)and to explore the potential mechanism.Methods We established a culture method of NK-92 cell lines in vitro.Lactate debydrogenase(LDH)cytotoxicity assays and cytokine release assays were performed to determine whether NK-92 cell lines could recognize and kill HCCs in vitro.At the same time,Nu/Nu mices were housed. Subcutaneous(sc)xenografts HepG2 models of human hepatocellular carcinoma were established.1×107NK-92 cells were intravenously(iv)injected through the tail vein on days 2,9,16,23 while the control group was injected with PBS in the same way.Tumor size, tumor volume, tumor mass and mouse survival status were closely observed in experimental and control groups.Mice were euthanized when tumor-bearing time reached 28 days.Xenograft tissues were taken for general observation.Sections were cut and processed for HE staining and immunofluorescence staining.The expression of glypican-3(GPC3)protein in xenografts tissue was clearly defined.Results NK-92 cell lines that were chronically cultured in vitro and maintained typical phenotypic characteristics of NK cells with good cellular activity.Enhanced cytotoxicity and IFN-γ production of NK-92 cell lines were identified by LDH and ELISA,indicating that NK-92 cell lines could recognize and kill different kinds of HCCs.In addition,NK-92 cell lines efficiently suppressed the growth of HCC xenografts in vivo.Tumor volume in experimental group was significantly reduced compared with control group and there was low a GPC 3 expression in experimental group through immunofluorescence and immunohistochemistry results, pointing to the possibility that the cytotoxicity of NK cells was correlated with GPC3 +HCCs.Conclusion NK cells provide a promising means of therapeutic intervention for HCCs.NK-92 cell lines could eliminate HCC cells in vitro and in vivo.The cytotoxicity of NK-92 cell lines may work by killing the GPC3-positive cells in the liver cancer tissue.In addition to the anti-tumor effect, NK cells also have cytotoxicity on pathogens such as bacteria and viruses.