Introduction: Individuals with Barrett’s metaplasia of the esophagus are at increased risk for developing adenocarcinoma of the esophagus. We propose to utilize a whole cell Granulocyte Macrophage Colony Stimulating Factor (GM-CSF)-secreting vaccine to protect against the development of cancer in a rat reflux model of esophageal carcinogenesis. Methods and Results: Three cancer-cell lines, JA, JB and AMY, were established from rat esophageal cancer, that had the capacity to produce carcinoma both orthotopically and heterotopically in nude mice. These cell lines shared molecular characteristics of human esophageal cancer cells including the over-expression of EGF receptors. MHC class I expression in the JA and JB cell lines was observed by flow cytometric analysis utilizing the mouse monoclonal (OX-18) antibody against MHC class I (Abcam®, Cambrige, MA) (Fig. 1). To develop vaccines from these tumor cell lines, each cell line was transfected with GM-CSF. JA cells produced GM-CSF (JA-GM-CSF) at the rate of 55 ng/24 hours/1×10⁶ cells, as measured by ELISA. Vaccine cells were tested for immunogenicity by irradiating them with 5000 Gy to prevent their propagation, and injection of 1×10⁷ cells/0.5ml in phosphate buffer solution subcutaneously into rats. GM-CSF transfected JA cells, promoted an inflammatory response at the vaccination site as seen by the infiltration of T-cells, Eosinophils, Macrophages, and the granuloma size that was greater than that seen in rats injected/vaccinated with GM-CSF negative cells. (Table 1). Conclusion: JA-GM-CSF cells act in a similar manner as previously reported GM-CSF-secreting whole cell vaccines. We have designed experiments to test the ability of JA-GM-CSF cells to prevent or delay recurrence of esophageal carcinogenesis in rats.
Table 1