Molecular and immunophenotypical characterization of progressive and regressive leukemia cell lines.

The P815 and P198 cell lines are clonally related mouse mastocytoma cell lines. They differ in their biologic behavior in that P815 is a progressive tumor cell line, whereas P198 is a regressive one. These cell lines have been extensively used as models for the study of tumor-host relationships and tumor immunology. Although some of their biological properties have been well documented, the molecular mechanisms underlying tumor progression or regression have not been completely elucidated. In this study, we characterized the growth behavior and immunophenotype of these two cell lines, and analyzed their gene profiles using a complementary deoxynucleic acid (cDNA) microarray composed of 514 immunologically relevant genes. Our data showed that the two cell lines exhibited quite dissimilar and contrasting growth characteristics when inoculated into syngeneic mice. P815 tumors grew unremittingly, while P198 tumors gradually regressed. From a molecular viewpoint, P815 cells showed a higher expression of genes promoting tumor growth, such as IGF-1, IL-8R, FGFR1, VEGF-A, and VEGF-B. On the other hand, P198 tumor cells expressed CD11b and CD80, which favor the recruitment of lymphocytes and antigen-presenting cells (APCs), as well as the elicitation of antitumor immunity. P198 tumor cells also depicted a higher expression of genes inhibiting tumor growth, such as TNF-alpha, SOCS-1, CIS1, 4-1BB, and GDF-10. In conclusion, our results contribute further information in the understanding of the molecular mechanisms associated with the regression and progression of P815 and P198 tumor cells.