Objective: To investigate the effects of B7 costimulatory molecule on inducing anti-tumor immune response to cervical carcinoma in vivo.
Methods: We transfected mouse B7 gene into murine cervix carcinoma cell line U14 by electroporation, and obtained several high-expressed mB7 U14 cell clonal strains (B7+ U14) detected by reverse transcription polymerase chain reaction (RT-PCR). In vivo experiments: (1) 1 x 10(7) B7+ U14 cells were inoculated into the back of inbred 615-strain mice by subcutaneously injection to determine their tumorigenicity (n = 6). (2) The mice primed by B7+ U14 (1 x 10(6)) cells were re-challenged with 1 x 10(7) wild type U14 to observe the immune protection of these mice against the wild type U14 (n = 6). As control, (3) wild type U14 cells were inoculated the same as the experimental group (1) (n = 6). (4) The mice both primed and re-challenged with 1 x 10(7) wild type U14 the same as the experimental group (2) (n = 6). All mice lifetime and tumor sizes were recorded. In vitro cytotoxiaty assay: the mice were immunized with B7+ U14 or the wild type U14 by intraperitoneal injection (n = 4 x 2) and two weeks late those mice spleen cells were obtained and cultured for two days. The cytotoxiaty of these cells against the wild U14 was detected by methyl thiazolyl tetrazolium assay.
Results: RT-PCR showed positive results in B7+ U14 cells, while negative in U14 cells. In vivo experiment: (1) after the inoculation of the B7+ U14 cells into the back of inbred mice, they lost their tumorigenicity greatly compared to wild type U14 (P < 0.01). (2) Primed by B7+ U14, mice protected themselves effectively against rechallenged (P < 0.01). In vitro cytotoxiaty assay, the cytotoxic T lymphocytes (CTLs) induced by B7+ U14 had a higher cytotoxiaty against the wild type U14 than that induced by wild type U14 (P < 0.01).
Conclusions: Cervical carcinoma cells transfected with constimulatory molecules B7 gene can decrease their tumorigenicity greatly, and induce anti-tumor immune protection of inbred mice against wild type U14 cells re-challenged. The results suggest that to transfect B7 gene into cervical cancer expression may be an effect method for treating cervical cancer in clinical.