Purification and identification of chemokines potentially involved in kidney-specific metastasis by a murine lymphoma variant: Induction of migration and NFκB activation

The ESb-MP cell line is the subclone of a highly malignant variant of murine methylcholanthrene-induced T lymphoma, ESb. When injected in vivo, ESb-MP cells metastasize to the kidney with high frequency, whereas a non- adherent variant, ESb cells, rarely form metastatic foci in the kidney. Our previous results showed that ESb-MP, but not ESb, cells were able to migrate in response to murine kidney-conditioned media (KCM). In an effort to characterize the tumor cell chemoattractant(s) produced by kidney cells, we found that the murine kidney mesangial cell line MES-13 released more chemotactic activity for ESb-MP cells than present in KCM. A major heparin- binding chemotactic activity was purified to homogeneity by sequential fast- performance liquid chromatography and reversed phase high-performance liquid chromatography. Amino acid sequencing of the formic acid-digested active fractions revealed that the purified protein was identical to murine MCP- I(JE) and its activity was neutralized by an anti-MCP-I(JE) antibody. Another chemokine, RANTES, was also purified from MES-13 cell supernatant. The chemotactic activity contained in the MES-13 cell supernatant and in murine KCM was neutralized in part by a combination of anti-MCP-I(JE) and anti- RANTES antibodies. We further examined the differences in the ESb-MP and ESb cells. Binding studies using a variety of radio-iodinated chemokines showed that although both ESb-MP and ESb cells expressed substantial levels of high- affinity binding sites for CC chemokines, only ESb-MP cells migrated in response to CC chemokines and these cells constitutively expressed higher levels of β2 integrin adhesion protein CDIIb than their parental ESb cells. CC chemokines also activated NFκB in ESb-MP but not in ESb cells. Our results indicate that CC chemokines selectively chemoattract and activate ESb-MP cells. Thus, locally produced chemokines, MCP-I(JE) and RANTES in particular, may contribute to the preferential metastasis of ESb-MP cells to the kidneys.