Enhancement of Anti-Tumor Immunity by Simultaneously Targeting Galectins and Its Associated Ligands (I)

Cancer target therapy is usually directed against growth factor receptors and/or its signal transduction pathways to induce cancer cell apoptosis or to suppress cancer cell invasiveness. However, tumor growth and metastasis is determined not only by cancer invasiveness, but also escape of anti-tumor immunity. Cancer invasiveness has recently been shown to mediate through maintenance of growth factor receptor （EGFR, VEGFR, PDGFR, TGFR etc.） expression by its lattice formation by the sugar-lectin agglutination with galectins such as galectin-3(Gal-3). The Gal-3 and/or Gal-1expression promotes not only cancer invasiveness but also proinflammatory reaction of cancer cells and suppression of anti-tumor immunity. We therefore propose here to raise a simultaneous multipotent targeting galectins expression for suppressing cancer invasiveness and augmenting tumor immunity by extracellular scavenging of galectins such as Gal-1 and Gal-3 or interrupting of intracellular Gal-1 and/or Gal-3 binding. Employing a fusion protein containing human Fc and truncated Gal-3 binding protein (Fc-tGal-3BP) which might scavenge extracellular Gal-1 and Gal-3 as well as EGF peptide-linked truncated Gal-3 and/or Gal-1 (EGF/Gal-1C, EGF/Gal-3C) that could block intracellular Gal-3 and/or Gal-1 function, this program project will target not only cancer biology regarding colon cancer cell invasiveness (subproject-1), radiosensitivity (subprohject-2) and cancer stem cell transformation (subproject-3), but also promote anti-tumor immunity in this subproject-4 by approaching following 3 specific aims: 1) To investigate a fusion protein linking truncated Gal-3 BP with human Fc fragment, called Fc-tGal-3 BP, can bind Gal-1 and Gal-3 and scavenge them via Fc receptor mediated phagocytosis. In addition, we will also test whether another fusion protein linking EGF peptide with truncated Gal-3 and/ or Gal-1 can target colon cancer cells but harmless to normal leukocytes. 2) Specific aim 2 is to study extracellular and intracellular targeting of Gal-1 and/or Gal-3 could mediate enhancement of anti-tumor immunity including natural killer cell, CD8 T cell cytotoxicity and Treg cell re-population, particularly the targeting effects in conjunction with chemotherapy. 3) Specific aim 3 is to test whether the recombinant protein drugs can suppress the liver and lung metastasis of colon cancer cells in severe combined immunodeficiency mice reconstituted by human peripheral mononuclear cells (PBMC). A short-term localization of tumor cells into liver and lungs in 6 hours will be assessed by viable dye labeled colon cancer cells with and without targeting manipulation, and the long term metastasis will be assessed after 3 to 6 weeks. In vivo plasma Gal-1 and/ Gal-3 levels as well as anti-tumor immunity of reconstituted PBMC after target therapy will be correlated to metastasis counts. Results from this study will demonstrate in vitro and in vivo that scavenging and competition of Gal-1 and/or Gal-3 enhance anti-tumor immunity in addition to suppression of colon cancer invasiveness, radioresistance and EMT in vitro and in animal models. We will collaborate with 3 other subprojects to study the immune responses to the chemoresistant, radioresistant and epithelial-mesenchymal transition cancer cells with and without targeting Gal-1 and Gal-3 expression. We anticipate to complete the proposed studies in the first 2 years, and try to adjust the optimal recombinant constructs to improve in vivo stability, half-life and functions in the 3rd year.

Project ID:PC10006-0139
External Project ID:NSC100-2325-B166-001