Abstract: AIM: To investigate the effects of interleukin 6(IL-6) on the expression of breast cancer antigen (CA15-3) and carcinoembryonic antigen (CEA) in the breast cancer cells.METHODS: 1176 bp cDNA that contained the IL-6 protein encoding sequence was inserted into the Pci-neo mammalian expression vector, which contains a neomycin resistance selective marker.The vector was introduced into MCF-7 breast cancer cells by lipofection.Secretion of IL-6 in the culture media was measured by ELISA and the concentrations of CA15-3, CEA and CA125 in the culture media were quantitated by micropartical enzyme immunoassay (MEIA).RESULTS: The secretion of IL-6 (338.5±22.6 pg·10^-6 cells) in MCF-7 cells that contained the exogenous IL-6 gene significantly higher than that in the control parental MCF-7cells (25.4±4.6 pg·10^-6 cells) or the MCF-7 cells which only contained the Pci-neo mammalian expression vector (19.6±3.0 pg·10^-6 cells, P <0.01).After three days of incubation, the level of CA15-3 in the MCF-7 cells which contained the exogenous IL-6 gene (14.9±2.3 pg·10^-6 cells) was higher than that in the parental MCF-7 cells (6.6±1.5 pg·10^-6 cells) or the MCF-7 cells which only contained the Pci-neo vector (3.4±0.07 pg·10^-6 cells, P <0.05).The CA125 in the MCF-7 cells (38.8±5.1 pg·10^-6 cells) which contained the exogenous IL-6 gene significantly higher than that in the parental MCF-7 cells (10.0±1.6 pg·10^-6 cells) or the MCF-7 cells which only contained the Pcineo vector (14.6±2.2 pg·10^-6 cells, P <0.01 or P < 0.05).But the transfer of the exogenous IL-6 gene had not significantly increased the concentration of CEA in the culture medium compared to that in the control MCF-7 cells (P>0.05).CONCLUSION: IL-6 can induce the expression of tumor associated antigen and improve the antigenicity of tumor cells.And it suggest that IL-6maybe result in an increased immunological response.

Key words: interleukin 6, breast cancer cells, breast cancer antigen, carcinoembryonic antigen