Lymph-derived soluble Clever-1 : Effect on cancer cell viability

Abstract

Cancer is one of the most important causes of premature death. Even though the treatment of cancer has seen considerable advancements in the past decades, there are still numerous cancers without effective treatment. Metastasis and the ability of most cancers to develop resistance against cancer medicine, particularly cancer immunotherapy, hinder the efficacy of cancer treatments. One culprit in cancer immunotherapy resistance is Clever-1, which is an immunosuppressive transmembrane protein expressed on endothelial cells and macrophages. The aim of this thesis was to study how the soluble Clever-1 in human lymph affects the viability of breast cancer cells in vitro, to better understand the metastatic process. Two breast cancer cell lines representing low (T47D) and high (MDA-MB-231) lymphatic metastasis capacity were chosen for the experiments. The proliferation of the cancer cells was compared between growth mediums supplemented with either Clever-1+ or Clever-1- human lymph. The lymph was obtained from three healthy donors and Clever-1 was depleted from the lymph by immunoprecipitation using anti-Clever-1 antibodies. The Clever-1-depletion was validated by two distinct methods: in-house Clever-1 time-resolved fluorometric immunoassay of the Clever-1-depleted lymph and by gel electrophoresis of the Clever-1 immunoprecipitate. There was no relationship between soluble Clever-1 in lymph and the viability of the breast cancer cells. This provides important preliminary information about the roles of soluble Clever-1 in metastasis. Further studies are required on the several other steps of metastasis, such as adhesion and transmigration. Additionally, recombinant Clever-1 could be utilized to eliminate the other contents of lymph as confounding factors.