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Updated: May 5, 2026
Studying the Effects of Tumor-Secreted Paracrine Ligands on Macrophage Activation using Co-Culture with Permeable Membrane Supports
Published on: November 28, 2019
A lovastatin-elicited genetic program inhibits M2 macrophage polarization and enhances T cell infiltration into
Abstract:
Beyond their ability to inhibit cholesterol biosynthesis, the statins have pleiotropic effects that include anti-inflammatory and immunomodulatory activities. Statins could have clinical utility, alone or in combination with other chemotherapeutics, in the treatment of cancer. The mechanisms that underlie the anti-tumor activity of the statins are nonetheless poorly defined. No studies have analyzed how they alter the tumor-associated leukocyte infiltrate, a central factor that influences tumor stroma and cancer evolution. Here we used HER2/neu transgenic (Tg-neu) mice to analyze the effect of lovastatin (Lov) on the inflammatory reaction of spontaneous mammary tumors. Lov treatment of tumor-bearing Tg-neu mice did not alter growth of established tumors, but significantly reduced the number of new oncogenic lesions in these mice. Moreover, Lov inhibited the growth of newly implanted Tg-neu tumors in immunocompetent but not in immunodeficient mice. We found that Lov enhanced tumor infiltration by effector T cells, and reduced the number of immunosuppressive and pro-angiogenic M2-like tumor-associated macrophages (TAM). Concomitantly, the drug improved the structure and function of the tumor vasculature, measured as enhanced tumor oxygenation and penetration of cytotoxic drugs. Microarray analysis identified a Lov-elicited genetic program in Tg-neu tumors that might explain these effects; we observed Lov-induced downregulation of placental growth factor, which triggers aberrant angiogenesis and M2-like TAM polarization. Our results identify a role for lovastatin in the shaping and re-education of the inflammatory infiltrate in tumors, with functional consequences in angiogenesis and antitumor immunity.
Insights
Lovastatin (Lov) reduces new tumor formation by enhancing anti-tumor immunity and improving blood vessel function. This statin reshapes the tumor
Area of Science:
- Oncology
- Immunology
- Pharmacology
Background:
- Statins possess anti-inflammatory and immunomodulatory effects beyond cholesterol inhibition.
- Potential clinical utility of statins in cancer treatment, alone or combined with chemotherapy.
- Mechanisms of statin anti-tumor activity, particularly their impact on tumor-infiltrating leukocytes, remain unclear.
Purpose of the Study:
- To investigate the effect of lovastatin (Lov) on the inflammatory infiltrate and anti-tumor immunity in spontaneous mammary tumors.
- To elucidate the mechanisms by which lovastatin influences tumor growth, angiogenesis, and immune cell populations.
Main Methods:
- Utilized HER2/neu transgenic (Tg-neu) mice to model spontaneous mammary tumors.
- Administered lovastatin to tumor-bearing mice and assessed tumor growth, lesion development, and immune cell infiltration.
- Analyzed tumor vasculature, oxygenation, and drug penetration, alongside gene expression profiling (microarray).
Main Results:
- Lovastatin did not affect established tumor growth but significantly reduced new lesion formation in Tg-neu mice.
- Lovastatin inhibited new tumor growth in immunocompetent but not immunodeficient mice, indicating an immune-dependent mechanism.
- Lovastatin promoted effector T cell infiltration, reduced immunosuppressive M2-like tumor-associated macrophages (TAMs), and improved tumor vasculature and oxygenation.
- Lovastatin downregulated placental growth factor (PlGF), a key mediator of aberrant angiogenesis and M2-like TAM polarization.
Conclusions:
- Lovastatin modulates the tumor inflammatory infiltrate, enhancing anti-tumor immunity and improving tumor microenvironment.
- Lovastatin's effects on TAMs and angiogenesis contribute to its anti-tumorigenic properties.
- Lovastatin shows promise as an adjuvant therapy for cancer by reprogramming the immune response and vascularization.
