| Alpha-halomethylene phosphonate analogues of lysophosphatidic acid (LPA) are potent pan-LPA receptor antagonists and inhibitors of lysophospholipase D (lysoPLD, also autotoxin, ATX). Through G-protein-coupled receptors (GPCRs), LPA was found to promote cell proliferation, invasion, and angiogenesis. The production of LPA by ATX is also linked to enhanced invasion and metastasis. Thus, LPA antagonists with ATX inhibitory properties have significant potential as signal transduction modifiers (STMs) in cancer therapy.;Herein, we developed various mouse cancer xenograft models addressing different aspects in cancer research. The engineered tumor xenograft models were generated using an in situ cross-linkable synthetic extracellular matrix (sECM) as cell delivery carrier. In vitro wound healing assays and cell invasion assays in this work showed that treatment of human breast cancer cells MDA-MB-231 and nonsmall cell lung cancer cells A549 with diastereomeric LPA antagonists 1a and 1b significantly inhibited cell proliferation, invasion and migration. The established xenograft model was applied, and hydrogel was seeded with MB-231 or A549 cells, and injected subcutaneously into nude mice. Once reaching desired tumor volume, animals were treated with vehicle alone or 3 mg/kg of the 1a and 1b for 2 weeks. Animals treated with the 1a and 1b developed tumors of significantly smaller volume compared with those in the control. Immunohistochemical analysis revealed the ability of the 1a and 1b to inhibit tumor cell angiogenesis. To further depict the effects of LPA antagonists on angiogenesis, we developed a plug model using the hydrogel with heparin-DTPH and growth factors. Blood vessels were calculated and hemoglobin (Hb) content was measured for the capability of angiogenesis inhibition. Finally, we described the successful use of mesenchymal stem cells (MSCs) to allow tumor growth in immunocompetent C3H mice. This overcomes the inherent weakness of immunodeficient animal xenograft model and provides a more predictive model for drug evaluation.;Together, the results and ongoing projects using newly developed tumor xenograft models suggest that LPA antagonists are potent anticancer agents blocking cancer metastasis and angiogenesis. The anti -isomer 1b was a better pan-antagonist for LPA GPCRs and inhibitor for ATX both in vitro and in vivo, and provided a promising candidate for cancer therapy. |
