Effect of natural killer cell line NK-92 against human ovarian carcinoma cells in vitro and in vivo

Objective To study the cytotoxic activity of NK-92 cells irradiated against human ovarian cancer. Methods NK-92 cells were exposed to different doses of radiation and assayed for proliferation by a standard ~3H-thymidine incorporation assay and cell count by using trypan blue exclusion. The cytotoxic activity of NK-92 cells against targets was measured in a standard ~(51)Cr-release assay in vitro. The effectiveness of irradiated NK-92 cells on ovarian cancer was compared with the control group of cancers (without injection of irradiated NK-92 cells). Results (1) In vitro:The proliferation of NK-92 cells was inhibited by radiation of 4, 8 and 16 Gy, respectively. From the ~3H-thymidine incorporation data, irradiation by 4 Gy reduced cell proliferation to 29% of control, while 8 Gy reduced proliferation to 6%. The cytotoxicity of NK-92 cells at 4 Gy 2 days following irradiation was approximately 42%-62% for ovarian cancer cell HO-8910, while it was 33%-58% at 8 Gy. (2) In vivo:Tumor size in treatment group was (0.047±0.019) cm~3 on day 30 after inoculation, and (0.167±0.021) cm~3 on day 40 and (0.343±0.022) cm~3 on day 50, while the sizes were smaller in treatment group (P0.01). In addition, the tumor group animals died between 74-82 days after injection of HO-8910 cells, while the treatment group animals were alive over 120 days (P0.01). Conclusion Our study indicates that injection of irradiated NK-92 cells may be a potentially effective treatment for human ovarian carcinoma.