Endogenous IL-12 triggers an antiangiogenic program in melanoma cells

Abstract

The IL12RB2 gene acts as a tumor suppressor in human B cell malignancies. Indeed, Il12rb2 knockout (KO) mice develop spontaneously B cell tumors, but also lung epithelial tumors. This latter phenotype may be related to (i) impairment of host IL-12-mediated immunosurveillance and/or (ii) IL-12 inability to inhibit directly the growth of IL-12 unresponsive malignant cells. To address this issue, we transplanted IL-12R ؉ B16 melanoma cells into syngeneic Il12rb2 KO mice with the following rationale: (i) these mice have severe defects in IFN-␥ production, as well as in cytotoxic T lymphocyte and natural killer cell cytotoxicity, and (ii) they produce but do not use IL-12 that can potentially bind to and target tumor cells only. Il12rb2 KO mice displayed higher endogenous serum levels of IL-12 and developed smaller B16 tumors than WT animals. These tumors showed reduced proliferation, increased apoptosis, and defective microvessel formation related to down-regulated expression of a set of proangiogenic genes previously unrelated to IL-12. Such effects depended on direct activity of endogenous IL-12 on tumor cells in KO mice, and hydrodynamic delivered IL-12 caused further reduced tumorigenicity of B16 cells in these mice. A previously undescribed mechanism of the IL-12 antitumor activity has been here identified and characterized.angiogenesis ͉ tumor immunology ͉ cytokines I nterleukin 12 is a heterodimeric cytokine bridging innate and adaptive immunity (1). IL-12, which belongs to a family of structurally related cytokines including IL-23 and IL-27 (2, 3), is formed by the IL12p35 and IL12p40 subunits (4) and binds to the IL-12R, composed of the ␤1 and the ␤2 chains. Both chains are needed for high affinity binding of the cytokine and initiation of signal transduction (5, 6). IL12p40 associates with the p19 subunit to form IL-23, which binds to a receptor composed of IL12R␤1 and IL-23R (2, 3). Therefore, the IL12p35 and the IL12R␤2 subunits are unique components of IL-12 and IL-12R, respectively. IL-12, which is produced predominantly by antigen-presenting cells, drives T helper (Th1) responses, enhances T and natural killer (NK) cell cytotoxicity, and induces IFN-␥ production by T and NK cells (4,[7][8][9]. In addition, we have shown that IL-12 contributes to the regulation of normal human B cell function through stimulation of IgM synthesis and IFN-␥ production (10).IL-12 exerts antitumor activity through IFN-␥-dependent and independent mechanisms (11-15), which include modulation of the immune system and antiangiogenesis (16)(17)(18). We have recently demonstrated that the IL12RB2 gene acts as a tumor suppressor in human chronic B cell malignancies (14) and, accordingly, that aging IL12rb2 knockout (KO) mice develop spontaneously B cell tumors. The same mice showed high incidence of lung epithelial tumors. This latter finding may be related to reduced immune surveillance, because of their deficient T and NK cell-mediated cytotoxicity (19), Th2-biased T cell differentiation (20), and/or lack of IL-12-mediated dir...

IL-12-dependent innate immunity arrests endothelial cells in G0–G1 phase by a p21Cip1/Waf1-mediated mechanism

“…However recent data may allow reconsidering this cytokine as a therapeutic tool in selected tumor subsets. Actually it has been reported that the in vivo tumor response to IL-12 is influenced by the molecular features of its receptor [63] and that IL-12 could be a candidate for tumor shrinkage observed during the treatment of early-stage non-small cell lung cancer with tyrosine kinase inhibitors (vandetanib, pazopanib) targeting angiogenic receptors [64,65]. …”

Autophagy is a protective response to ethanol neurotoxicity

“…8 A BECN1 shRNA plasmid (SA Biosciences, KH05670N) and MTOR shRNA plasmid (Addgene, 1855) have been reported previously. 36,37 Briefly, transfection of a GFP-LC3 or BECN1 shRNA or negative control shRNA into SH-SY5Y cells was performed by using Lipofectamine 2000 (Invitrogen, 11668-019) according to the manufacturer's protocol. Forty-eight h after the transfection, the cells were subjected to immunofluorescent or immunoblotting analysis.…”

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“…M.P. Colombo (Istituto Nazionale Tumori, Milano) and Guido Kroemer (INSERM, Paris, France), respectively, and extensively tested in the authors' laboratories (11,12). The N13 microglial cell was a kind gift of Dr. Paola Ricciardi-Castagnoli (Singapore Immunology Network, Singapore), and extensively tested in the authors' laboratory for cytokine and surface marker expression (13).…”