[Show abstract][Hide abstract] ABSTRACT: Activation of the oncogene AEG-1 (MTDH, LYRIC) has been implicated recently in the development of hepatocellular carcinoma (HCC). In mice, HCC can be initiated by exposure to the carcinogen DEN, which has been shown to rely upon activation of NF-kB in liver macrophages. Since AEG-1 is an essential component of NF-kB activation, we interrogated the susceptibility of mice lacking the AEG-1 gene to DEN-induced hepatocarcinogenesis. AEG-1-deficient mice displayed resistance to DEN-induced HCC and lung metastasis. No difference was observed in the response to growth factor signaling or activation of Akt, ERK and B-catenin, compared to wild-type control animals. However, AEG-1-deficient hepatocytes and macrophages exhibited a relative defect in NF-kB activation. Mechanistic investigations showed that IL-6 production and STAT-3 activation, two key mediators of HCC development, were also deficient along with other biological and epigenetics findings in the tumor microenvironment confirming that AEG-1 supports an NF-kB-mediated inflammatory state that drives HCC development. Overall, our findings offer in vivo proofs that AEG-1 is essential for NF-kB activation and hepatocarcinogenesis, and they reveal new roles for AEG-1 in shaping the tumor microenvironment for HCC development.
[Show abstract][Hide abstract] ABSTRACT: The term myeloid-derived suppressor cells (MDSCs) was first suggested in 2007 in order to reflect the origin and function of myeloid cells during immunosuppression in cancer and other pathologic conditions. Emerging evidence suggests that MDSCs suppress CTL and Th1 responses in malignant diseases while they regulate effective immune responses in parasitic and helminth infections as well as Th17 inflammatory response during autoim-mune diseases. Based on these data, the term myeloid regulatory cells (Mregs) more accurately reflects their function and interactions with different cells of the immune sys-tem during diseased conditions. Here, we provide evidence on the multifaceted function of Mregs during diseased states.-derived suppressor cells (MDSCs) were originally described as immunosuppressive cells of myeloid origin. These cells are known to be a heterogeneous mixture of myeloid cells at different stages of differentiation. They were initially named "immature myeloid cells" or "myeloid suppressor cells" (MSC) until they matured into MDSCs in 2007 (1). Most of the attention was initially focused on the role of these cells in cancer, because tumor-derived factors were shown to facilitate the production of MDSCs as well as their accumulation in the secondary lym-phoid tissues and at the tumor site. In mice, MDSCs are broadly defined by the expression of CD11b and Gr-1, and could be subdi-vided into monocytic (CD11b + Ly6C hi Ly6G −) and granulocytic (CD11b + Ly6C low Ly6G +) subsets (2). In human being, MDSCs are characterized by the expression of CD33 + CD11b + HLA-DR −/low . Human MDSCs are classified into monocytic and granulocytic subsets based on Lin − CD11b + CD14 + CD15 − and Lin − CD11b + CD14 − CD15 + , respectively (3). In fact, MDSCs reflect a mechanism by which myeloid regulatory cells (Mregs) suppress the host's anti-tumor immune responses in favor of the tumor. The ability of MDSCs to suppress anti-tumor Th1 and CTL immune responses has been demonstrated by their direct and indirect impacts on the immune system. The direct immune suppressive function of MDSCs is accomplished through at least three different pathways which include contact-dependent and/or contact-independent suppression of effector T cells (4– 8), induction of Tregs (9), and inhibition of T cell trafficking (10). Contact-dependent suppression of T cells by MDSCs causes nitration of tyrosine residues in the TcR–CD8 complex, thereby disrupting the tumor antigen-MHC class I recognition by the TcR (4). Suppression of T cell proliferation during stimulation with anti-CD3/CD28 antibodies was also shown to be due to a contact-dependent mechanism (5). Cell contact is also required for MDSC-mediated suppression of NK cells in patients with hepatocellular carcinoma (6). It was reported that membrane-bound TGF-β1 on MDSCs is responsible for MDSC-mediated suppression of NK cell cytotoxicity, NKG2D expression, and IFN-γ production (11). Recently, it was reported that granulocytic MDSC subset can negatively regulate NK cell activation and function in response to vaccinia virus infection via producing reactive oxygen species (12). Most groups have found contact-independent mech-anisms of T cell suppression by MDSCs releasing soluble factors such as IDO, arginase-1, nitric oxide, reactive oxygen species, and peroxynitrites (13, 14). MDSCs also produce IL-10 and TGF-β, resulting in the induction of Tregs in an antigen-specific manner (15). Finally, MDSCs can downregulate the expression of CD62L, which is an important receptor for T cell homing to the lymph nodes. This is accomplished by the expression of a disintegrin and metalloproteinase (ADAM)-17 on MDSCs which cleaves and results in shedding of the ectodomain of CD62L (10). Indirect mechanisms of T cell suppression by MDSCs, which are mediated by granulocytic subset, include expression of matrix metalloproteinases (MMPs). MMPs can support the bioavailabil-ity of VEGF, thereby acting as tumor angiogenic factors; MMPs can also help to break down the extracellular matrix, facilitating dissemination and metastasis of the tumor (16).
[Show abstract][Hide abstract] ABSTRACT: First identified almost two decades ago as a novel gene differentially expressed in human melanoma cells induced to terminally differentiate, MDA-7/IL-24 has since shown great potential as an anti-cancer gene. MDA-7/IL24, a secreted protein of the IL-10 family, functions as a cytokine at normal physiological levels and is expressed in tissues of the immune system. At supra-physiological levels, MDA-7/IL-24 plays a prominent role in inhibiting tumor growth, invasion, metastasis and angiogenesis and was recently shown to target tumor stem/initiating cells for death. Much of the attention focused on MDA-7/IL-24 originated from the fact that it can selectively induce cell death in cancer cells without affecting normal cells. Thus, this gene originally shown to be associated with melanoma cell differentiation has now proven to be a multi-functional protein affecting a broad array of cancers. Moreover, MDA-7/IL-24 has proven efficacious in a Phase I/II clinical trial in humans with multiple advanced cancers. As research in the field progresses, we will unravel more of the functions of MDA-7/IL-24 and define novel ways to utilize MDA-7/IL-24 in the treatment of cancer.
Advances in experimental medicine and biology 01/2014; 818:127-53. · 1.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Elucidating the mechanism of pathogenesis of breast cancer has greatly benefited from breakthrough advances in both genetically engineered mouse (GEM) models and xenograft transplantation technologies. The vast array of breast cancer mouse models currently available is testimony to the complexity of mammary tumorigenesis and attempts by investigators to accurately portray the heterogeneity and intricacies of this disease. Distinct molecular changes that drive various aspects of tumorigenesis, such as alterations in tumor cell proliferation and apoptosis, invasion and metastasis, angiogenesis, and drug resistance have been evaluated using the currently available GEM breast cancer models. GEM breast cancer models are also being exploited to evaluate and validate the efficacy of novel therapeutics, vaccines, and imaging modalities for potential use in the clinic. This review provides a synopsis of the various GEM models that are expanding our knowledge of the nuances of breast cancer development and progression and can be instrumental in the development of novel prevention and therapeutic approaches for this disease.
Advances in Cancer Research 01/2014; 121:331-82. · 6.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tumor vascularization is a highly complex process that involves the interaction between tumors and their surrounding stroma, as well as many distinct angiogenesis-regulating factors. Tumor associated macrophages (TAMs) represent one of the most abundant cell components in the tumor environment and key contributors to cancer-related inflammation. A large body of evidence supports the notion that TAMs play a critical role in promoting the formation of an abnormal tumor vascular network and subsequent tumor progression and invasion. Clinical and experimental evidence has shown that high levels of infiltrating TAMs are associated with poor patient prognosis and tumor resistance to therapies. In addition to stimulating angiogenesis during tumor growth, TAMs enhance tumor revascularization in response to cytotoxic therapy (e.g., radiotherapy), thereby causing cancer relapse. In this review, we highlight the emerging data related to the phenotype and polarization of TAMs in the tumor microenvironment, as well as the underlying mechanisms of macrophage function in the regulation of the angiogenic switch and tumor vascularization. Additionally, we discuss the potential of targeting pro-angiogenic TAMs, or reprograming TAMs toward a tumoricidal and angiostatic phenotype, to promote normalization of the tumor vasculature to enhance the outcome of cancer therapies.
[Show abstract][Hide abstract] ABSTRACT: Efficient cross-presentation of protein Ags to CTLs by dendritic cells (DCs) is essential for the success of prophylactic and therapeutic vaccines. In this study, we report a previously underappreciated pathway involving Ag entry into the endoplasmic reticulum (ER) critically needed for T cell cross-priming induced by a DC-targeted vaccine. Directing the clinically relevant, melanoma Ag gp100 to mouse-derived DCs by molecular adjuvant and chaperone Grp170 substantially facilitates Ag access to the ER. Grp170 also strengthens the interaction of internalized protein Ag with molecular components involved in ER-associated protein dislocation and/or degradation, which culminates in cytosolic translocation for proteasome-dependent degradation and processing. Targeted disruption of protein retrotranslocation causes exclusive ER retention of tumor Ag in mouse bone marrow-derived DCs and splenic CD8(+) DCs. This results in the blockade of Ag ubiquitination and processing, which abrogates the priming of Ag-specific CD8(+) T cells in vitro and in vivo. Therefore, the improved ER entry of tumor Ag serves as a molecular basis for the superior cross-presenting capacity of Grp170-based vaccine platform. The ER access and retrotranslocation represents a distinct pathway that operates within DCs for cross-presentation and is required for the activation of Ag-specific CTLs by certain vaccines. These results also reinforce the importance of the ER-associated protein quality control machinery and the mode of the Ag delivery in regulating DC-elicited immune outcomes.
The Journal of Immunology 11/2013; · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effects of modulating tetrahydrobiopterin (BH4) levels with a metabolic precursor, sepiapterin (SP), on dextran sodium sulfate (DSS) induced colitis and azoxymethane (AOM) induced colorectal cancer were studied. SP in the drinking water blocks DSS-induced colitis measured as decreased disease activity index (DAI), morphological criteria and recovery of Ca2+-induced contractility responses lost as a consequence of DSS treatment. SP reduces inflammatory responses measured as decreased numbers of infiltrating inflammatory macrophages and neutrophils and decreased expression of pro-inflammatory cytokines IL-1β, IL-6 and IL-17A. HPLC analyses of colonic BH4 and its oxidized derivative, dihydrobiopterin (BH2), are inconclusive although there is a trend for lower BH4:BH2 with DSS treatment that was reversed with SP. Reduction of colonic cGMP levels by DSS is reversed with SP by a mechanism sensitive to 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a specific inhibitor of the NO-sensitive soluble guanylate cyclase (sGC). ODQ abrogates the protective effects of SP on colitis. This plus the finding that SP reduces DSS enhanced protein Tyr nitration are consistent with DSS induced uncoupling of NOS. The results agree with previous studies demonstrating inactivation of sGC in DSS-treated animals as being important in recruitment of inflammatory cells and in altered cholinergic signaling and colon motility. SP also reduces the number of colon tumors in the DSS/AOM treated mice from 7 to 1 per unit colon length. Thus pharmacological modulation of BH4 with currently available drugs may provide a mechanism for alleviating some forms of colitis and potentially minimizing the potential for colorectal cancer in patients with colitis.
Journal of Pharmacology and Experimental Therapeutics 08/2013; · 3.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Although the large stress/heat shock proteins (HSPs), i.e. Hsp110 and Grp170, were identified over 30 years ago, these abundant and highly conserved molecules have received much less attention compared to other conventional HSPs. Large stress proteins act as molecular chaperones with exceptional protein-holding capability and prevent the aggregation of proteins induced by thermal stress. The chaperoning properties of Hsp110 and Grp170 are integral to the ability of these molecules to modulate immune functions and are essential for developing large chaperone complex vaccines for cancer immunotherapy. The potent anti-tumour activity of the Hsp110/Grp170-tumour protein antigen complexes demonstrated in preclinical studies has led to a phase I clinical trial through the National Cancer Institute's rapid access to intervention development (RAID) programme that is presently underway. Here we review aspects of the structure and function of these large stress proteins, their roles as molecular chaperones in the biology of cell stress, and prospects for their use in immune regulation and cancer immunotherapy. Lastly, we will discuss the recently revealed immunosuppressive activity of scavenger receptor A that binds to Hsp110 and Grp170, as well as the feasibility of targeting this receptor to promote T-cell activation and anti-tumour immunity induced by large HSP vaccines and other immunotherapies.
International Journal of Hyperthermia 07/2013; · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Recent observations suggest that immune-mediated tissue destruction is dependent upon coordinate activation of immune genes expressed by cells of the innate and adaptive immune systems. METHODS: Here, we performed a retrospective pilot study to investigate whether the coordinate expression of molecular signature mostly associated with NK cells could be used to segregate breast cancer patients into relapse and relapse-free outcomes. RESULTS: By analyzing primary breast cancer specimens derived from patients who experienced either 58--116 months (~5-9 years) relapse-free survival or developed tumor relapse within 9--76 months (~1-6 years) we found that the expression of molecules involved in activating signaling of NK cells and in NK cells: target interaction is increased in patients with favorable prognosis. CONCLUSIONS: The parameters identified in this study, together with the prognostic signature previously reported by our group, highlight the cooperation between the innate and adaptive immune components within the tumor microenvironment.
Journal of Translational Medicine 06/2013; 11(1):145. · 3.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have recently demonstrated that glucose-regulated protein 170 (Grp170), a stress-responsive molecular chaperone of the endoplasmic reticulum, can be exploited to stimulate anticancer immunity due to its superior antigen chaperoning and delivering capacity. The immune remodeling of the tumor microenvironment induced by a Grp170-based chaperone leads to immune responses that effectively control the progression of both primary neoplasms and their metastases. Our findings support the development of Grp170-based immunomodulating strategies to potentiate antitumor immune responses.
[Show abstract][Hide abstract] ABSTRACT: Gene therapy provides a novel platform for therapeutic intervention of several genetic and non-genetic disorders. With the recent developments in the field, a wide variety of viral and non-viral vectors have emerged that can deliver genetic payloads to target cells. However, non-targeted delivery of transgenes often results in undesirable effects, low tumor transduction, and reduced therapeutic index. In this review, we focus on some of the novel approaches that can be used to meet the present challenges in the field and translate the potential of cancer gene therapy from 'bench to bedside' in the near future.
Discovery medicine 05/2013; 15(84):309-317. · 2.97 Impact Factor