CCR6, the Sole Receptor for the Chemokine CCL20, Promotes Spontaneous Intestinal Tumorigenesis

Interactions between the inflammatory chemokine CCL20 and its receptor CCR6 have been associated with colorectal cancer growth and metastasis, however, a causal role for CCL20 signaling through CCR6 in promoting intestinal carcinogenesis has not been demonstrated in vivo. In this study, we aimed to determine the role of CCL20-CCR6 interactions in spontaneous intestinal tumorigenesis. CCR6-deficient mice were crossed with mice heterozygous for a mutation in the adenomatous polyposis coli (APC) gene (APCMIN/+ mice) to generate APCMIN/+ mice with CCR6 knocked out (CCR6KO-APCMIN/+ mice). CCR6KO-APCMIN/+ mice had diminished spontaneous intestinal tumorigenesis. CCR6KO-APCMIN/+ also had normal sized spleens as compared to the enlarged spleens found in APCMIN/+ mice. Decreased macrophage infiltration into intestinal adenomas and non-tumor epithelium was observed in CCR6KO-APCMIN/+ as compared to APCMIN/+ mice. CCL20 signaling through CCR6 caused increased production of CCL20 by colorectal cancer cell lines. Furthermore, CCL20 had a direct mitogenic effect on colorectal cancer cells. Thus, interactions between CCL20 and CCR6 promote intestinal carcinogenesis. Our results suggest that the intestinal tumorigenesis driven by CCL20-CCR6 interactions may be driven by macrophage recruitment into the intestine as well as proliferation of neoplastic epithelial cells. This interaction could be targeted for the treatment or prevention of malignancy

Targeting IL-17A in Multiple Myeloma: A Potential Novel Therapeutic Approach in Myeloma

We have previously demonstrated that interleukin-17A (IL-17) producing Th17 cells are significantly elevated in blood and bone marrow (BM) in multiple myeloma (MM) and IL-17A promotes MM cell growth via the expression of IL-17 receptor. In this study, we evaluated anti-human IL-17A human monoclonal antibody (mAb), AIN457 in MM. We observe significant inhibition of MM cell growth by AIN457 both in the presence and absence of BM stromal cells (BMSC). While IL-17A induces IL-6 production, AIN457 significantly down-regulated IL-6 production and MM cell-adhesion in MM-BMSC co-culture. AIN-457 also significantly inhibited osteoclast cell–differentiation. More importantly, in the SCIDhu model of human myeloma administration of AIN-457 weekly for 4 weeks after the first detection of tumor in mice led to a significant inhibition of tumor growth and reduced bone damage compared to isotype control mice. To understand the mechanism of action of anti-IL-17A mAb, we report here, that MM cells express IL-17A. We also observed that IL-17A knock-down inhibited MM cell growth and their ability to induce IL-6 production in co-cultures with BMSC. These pre-clinical observations suggest efficacy of AIN 457 in myeloma and provide the rationale for its clinical evaluation for anti-myeloma effects and for improvement of bone disease

Loss of GABARAP mediates resistance to immunogenic chemotherapy in multiple myeloma

: Immunogenic cell death (ICD) is a form of cell death by which cancer treatments can induce a clinically relevant anti-tumor immune response in a broad range of cancers. In multiple myeloma (MM), the proteasome inhibitor bortezomib is an ICD inducer and creates durable therapeutic responses in patients. However, eventual relapse and resistance to bortezomib appear inevitable. Here, by integrating patient transcriptomic data with an analysis of calreticulin (CRT) protein interactors, we found that GABARAP is a key player whose loss prevented tumor cell death from being perceived as immunogenic after bortezomib treatment. GABARAP is located on chromosome 17p, which is commonly deleted in high-risk MM patients. GABARAP deletion impaired the exposure of the eat-me signal CRT on the surface of dying MM cells in vitro and in vivo, thus reducing tumor cell phagocytosis by dendritic cells and the subsequent anti-tumor T cell response. Low GABARAP was independently associated with shorter MM patient survival and reduced tumor immune infiltration. Mechanistically, we found that GABARAP deletion blocked ICD signaling by decreasing autophagy and altering Golgi apparatus morphology, with consequent defects in the downstream vesicular transport of CRT. Conversely, upregulating autophagy using rapamycin restored Golgi morphology, CRT exposure and ICD signaling in GABARAPKO cells undergoing bortezomib treatment. Therefore, coupling an ICD inducer, like bortezomib, with an autophagy inducer, like rapamycin, may improve patient outcomes in MM, where low GABARAP in the form of del(17p) is common and leads to worse outcomes

Histone deacetylase inhibitors: potential targets responsible for their anti-cancer effect

The histone deacetylase inhibitors (HDACi) have demonstrated anticancer efficacy across a range of malignancies, most impressively in the hematological cancers. It is uncertain whether this clinical efficacy is attributable predominantly to their ability to induce apoptosis and differentiation in the cancer cell, or to their ability to prime the cell to other pro-death stimuli such as those from the immune system. HDACi-induced apoptosis occurs through altered expression of genes encoding proteins in both intrinsic and extrinsic apoptotic pathways; through effects on the proteasome/aggresome systems; through the production of reactive oxygen species, possibly by directly inducing DNA damage; and through alterations in the tumor microenvironment. In addition HDACi increase the immunogenicity of tumor cells and modulate cytokine signaling and potentially T-cell polarization in ways that may contribute the anti-cancer effect in vivo. Here, we provide an overview of current thinking on the mechanisms of HDACi activity, with attention given to the hematological malignancies as well as scientific observations arising from the clinical trials. We also focus on the immune effects of these agents

Two different molecular pathways of immunomodulation by retinoids and carotenoids.

Epidemiological studies suggest that both retinoid and carotenoid intakes are inversely correlated with the incidence of human cancers. Animal studies show that both retinoids and carotenoids inhibit tumor cell growth. Both retinoids and carotenoids activate the cytotoxicity function of macrophages in animal experiments. The purpose of this study is to evaluate the molecular mechanism for 13-cis retinoic acid (13-cRA) and beta-carotene (BC) induced immunomodulation which could explain their anti-cancer affects. The effects of 13-cRA and BC were studied on various subpopulations of T-lymphocytes both in vitro and in vivo. For in vitro studies, peripheral blood mononuclear cells (PBMC) were incubated with test compounds at clinically achievable concentrations (10⁻⁸M) for three days. Then the cells were stained with monoclonal antibodies followed by the analysis of flow cytometer. For in vivo studies, PBMC were collected from Barrett's esophagus or oral leukoplakia patients during treatment with 13-cRA (1mg/kg/day) or BC (30 mg/day), respectively. Then the cells were analyzed with monoclonal antibodies and flow cytometry. Both compounds showed the capability of stimulating different subpopulations of T-lymphocytes. 13-cRA predominantly increased the number of T-helper cells, their interleukin 2 (IL-2) receptors and their response to mitogens. Whereas, BC elevated the number of Natural Kill (NK) cells, their IL-2 receptors and their cytotoxicity against K562 target cells. Though these immunomodulatory effects appeared to be unaffected by the presence and cytotoxic functions of macrophages, cytokines seemed to have an important role in the retinoid- and carotenoid-induced immunomodulation. Plasma levels of IL-2 and tumor necrosis factor (TNF) measured by ELISA procedures were increased in patients treated for two months with 13-cRA and BC respectively. Anti-IL-2 and anti-TNF antibodies blocked the retinoic- and carotenoid-induced immunomodulation in in vitro studies. These results indicate that 13-cRA, activating T-helper cells with IL-2 production, and BC, activating NK cells with TNF release, induced immunostimulation which might be able to provide the anti-cancer affects in part seen in epidemiological studies

Immunomodulation in humans caused by beta-carotene and vitamin A

Carotenoids and retinoids can stimulate some human immune responses. These include cytoine release with anti-tumor cell activity, increased natural killer cells and activated lymphocytes after both in vitro and in vivo treatment with beta carotene. Such stimulations seem only partly due to retinoids formed from carotenoid metabolism and may be due to effects caused by the structure of beta carotene. Changes in immune functions could explain in part the cancer resistance provided by high carotenoid or retinoid intakes in animals. © 1990 Pergamon Press plc

Immunomodulation in humans caused by beta-carotene and vitamin A

Carotenoids and retinoids can stimulate some human immune responses. These include cytoine release with anti-tumor cell activity, increased natural killer cells and activated lymphocytes after both in vitro and in vivo treatment with beta carotene. Such stimulations seem only partly due to retinoids formed from carotenoid metabolism and may be due to effects caused by the structure of beta carotene. Changes in immune functions could explain in part the cancer resistance provided by high carotenoid or retinoid intakes in animals. © 1990 Pergamon Press plc