Localization of transfected B7-1 (CD80) DNA in human melanoma cells after particle-mediated gene transfer

Storage Conditions and Passages Alter IL-6 secretion in C26 adenocarcinoma cell lines

The C26 adenocarcinoma tumor line is frequently used to establish peripheral tumors in mice for the study of cancer cachexia and cancer-related fatigue. Recently, we have noticed a progressive decline in the effects of tumor growth on our biological and behavioral measures in the tumor-bearing mice. Therefore, we compared effects of three aliquots of the C26 tumor cell line that differed in storage condition and number of passages on cytokine secretion, tumor growth, weight loss and fatigue behavior. Three aliquots of the C26 tumor line were selected as alpha (α), beta (β), and gamma (γ). Aliquot α was an original C26 stock line that had been stored at −80 °C. Aliquot β was stored in liquid nitrogen. Aliquot γ was taken from aliquot β and passaged three times. The three aliquots of the C26 tumor line showed differences in IL-6 mRNA and protein secretion in vitro, with aliquot β showing the greatest IL-6 secretion. These differences were mirrored in vivo. Plasma IL-6 levels were elevated in all tumor bearing mice but was greatest in group β mice. Carcass weight was decreased in all three tumor groups. Brain expression of IL-1β mRNA was greatest in group β and group β demonstrated the greatest decline in running activity at day 19.

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Storage conditions and number of passages influence C26 tumor cell secretion of cytokines.

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Variations in C26 aliquots may explain differences observed between laboratories using the same cell line.

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We recommend always storing cell lines in liquid nitrogen and limiting the number of passages before use in experiments.

Anti-gastric cancer active immunity induced by FasL/B7-1 gene-modified tumor cells

AIM: To study the activation of cytotoxic T lymphocytes (CTLs) against gastric cancer cells induced by FasL/B7-1 (FB-11) gene-modified tumor cells, and to explore whether co-expression of FasL and B7-1 in SGC-7901 tumor cells could initiate synergistic antitumor effect.

METHODS: FasL and B7-1 genes were transfected into human SGC-7901 gastric cancer cells with adenovirus vectors. The positive clones were selected by G418. FasL and B7-1 genes were detected by flow cytometry and RT-PCR. Abdominal infiltrating lymphocytes and sensitized spleen cells were obtained from mice that were immunized with SGC-7901/FB-11 or wild type SGC-7901 cells intraperitoneally, and cytotoxicity of these CTLs against tumor cells was determined by MTT assay.

RESULTS: Flow cytometry and RT-PCR showed that FasL and B7-1 genes were highly expressed. FasL and B7-1 transfected cancer cells had a high apoptosis index. DNA laddering suggested that FasL and B7-1 genes induced gastric cancer cell apoptosis. FasL⁺/B7-1⁺SGC-7901 cells (SGC-7901/FB-11) were inoculated subcutaneously in the dorsal skin of C57BL/6 mice and then decreased their tumorigenicity greatly (z = 2.15-46.10, P<0.01). SGC-7901/FB-11 cell-sensitized mice obtained protective immune activity against the rechallenge of wild type SGC-7901 cells (z = 2.06-44.30, P<0.05). The cytotoxicity of CTLs induced by SGC-7901/FB-11 cells against SGC-7901 was significantly higher than that of CTLs activated by wild-type SGC-7901 cells (84.1±2.4% vs 30.5±2.3%, P<0.05).

CONCLUSION: FasL and B7-1 genes can effectively promote the activity of CTLs against gastric cancer cells. FasL/B7-1 molecules play an important role in CTL cytotoxicity.