The role of immune cells in the tumor microenvironment

The immunoregulatory mechanisms of carcinoma for its survival and development

The immune system in patients detects and eliminates tumor cells, but tumors still progress persistently. The mechanisms by which tumor cells survive under the pressure of immune surveillance are not fully understood. This review is to present the evidence from clinical studies, showing a significant correlation of clinicopathological features of carcinoma with: (1) the loss of classical human leukocyte antigen class I, (2) the up-regulation of non-classical human leukocyte antigen class I, pro-apoptotic Fas ligand and receptor-binding cancer antigen expressed on SiSo cells I, and (3) the formation of immunosuppressive microenvironment by up-regulation of transforming growth factor-beta, Galectin-1, inhibitory ligand B7s, indoleamine 2,3-dioxygenase and arginase, as well as by recruitment of tumor-induced myeloid-derived suppressor cells and regulatory T cells. All of these factors may together protect carcinoma cells from the immune-cytotoxicity.

Forcing form and function: biomechanical regulation of tumor evolution

Cancer cells exist in a constantly evolving tissue microenvironment of diverse cell types within a proteinaceous extracellular matrix. As tumors evolve, the physical forces within this complex microenvironment change, with pleiotropic effects on both cell- and tissue-level behaviors. Recent work suggests that these biomechanical factors direct tissue development and modulate tissue homeostasis, and, when altered, crucially influence tumor evolution. In this review, we discuss the biomechanical regulation of cell and tissue homeostasis from the molecular, cellular and tissue levels, including how modifications of this physical dialogue could contribute to cancer etiology. Because of the broad impact of biomechanical factors on cell and tissue functions, an understanding of tumor evolution from the biomechanical perspective should improve risk assessment, clinical diagnosis and the efficacy of cancer treatment.

Comparative Membranome expression analysis in primary tumors and derived cell lines

Despite the wide use of cell lines in cancer research, the extent to which their surface properties correspond to those of primary tumors is poorly characterized. The present study addresses this problem from a transcriptional standpoint, analyzing the expression of membrane protein genes--the Membranome--in primary tumors and immortalized in-vitro cultured tumor cells. 409 human samples, deriving from ten independent studies, were analyzed. These comprise normal tissues, primary tumors and tumor derived cell lines deriving from eight different tissues: brain, breast, colon, kidney, leukemia, lung, melanoma, and ovary. We demonstrated that the Membranome has greater power than the remainder of the transcriptome when used as input for the automatic classification of tumor samples. This feature is maintained in tumor derived cell lines. In most cases primary tumors show maximal similarity in Membranome expression with cell lines of same tissue origin. Differences in Membranome expression between tumors and cell lines were analyzed also at the pathway level and biological themes were identified that were differentially regulated in the two settings. Moreover, by including normal samples in the analysis, we quantified the degree to which cell lines retain the Membranome up- and down-regulations observed in primary tumors with respect to their normal counterparts. We showed that most of the Membranome up-regulations observed in primary tumors are lost in the in-vitro cultured cells. Conversely, the majority of Membranome genes down-regulated upon tumor transformation maintain lower expression levels also in the cell lines. This study points towards a central role of Membranome genes in the definition of the tumor phenotype. The comparative analysis of primary tumors and cell lines identifies the limits of cell lines as a model for the study of cancer-related processes mediated by the cell surface. Results presented allow for a more rational use of the cell lines as a model of cancer.

ATP confers tumorigenic properties to dendritic cells by inducing amphiregulin secretion

ATP, which has an important proinflammatory action as danger signal, induces the semimaturation of dendritic cells (DCs) that can be associated with immune tolerance. We identified epidermal growth factor receptor ligands as target genes of ATPγS, a slowly hydrolyzed ATP derivative, by a gene profiling approach in DCs. Amphiregulin was the most highly up-regulated gene in response to ATPγS. Human monocyte-derived DCs and mouse bone marrow-derived DCs released amphiregulin (AREG) after purinergic receptor activation, with a contribution of P2Y(11) and A(2B) receptor, respectively. Supernatants of LPS+ATPγS-stimulated DCs induced smooth muscle cell and Lewis Lung Carcinoma (LLC) cell growth in vitro. The coinjection of LPS+ATPγS-stimulated DCs or their supernatants with LLC cells increased tumor weight in mice compared with LPS-treated DCs. The preincubation of LPS+ATPγS-treated DC supernatants with an anti-AREG blocking antibody inhibited their positive effect on smooth muscle cell density and tumor growth. The present study demonstrates for the first time that DCs can be a source of AREG. ATP released from tumor cells might exert a tumorigenic action by stimulating the secretion of AREG from DCs. Antagonists of purinergic receptors expressed on DCs and anti-AREG blocking antibodies could have a therapeutic potential as antitumor agents.

Local and distant immunity induced by intralesional vaccination with an oncolytic herpes virus encoding GM-CSF in patients with stage IIIc and IV melanoma

BACKGROUND

An oncolytic herpes simplex virus engineered to replicate selectively in tumor cells and to express granulocyte-macrophage colony-stimulating factor (GMCSF) was tested as a direct intralesional vaccination in melanoma patients. The work reported herein was performed to better characterize the effect of vaccination on local and distant antitumor immunity.

METHODS

Metastatic melanoma patients with accessible lesions were enrolled in a multicenter 50-patient phase II clinical trial of an oncolytic herpesvirus encoding GM-CSF (Oncovex(GM-CSF)). An initial priming dose of 10(6) pfu vaccine was given by intratumoral injection, followed by 10(8) pfu every 2 weeks to 24 total doses. Peripheral blood and tumor tissue were collected for analysis of effector T cells, CD4(+)FoxP3(+) regulatory T cells (Treg), CD8(+)FoxP3(+) suppressor T cells (Ts), and myeloid-derived suppressive cells (MDSC).

RESULTS

Phenotypic analysis of T cells derived from tumor samples suggested distinct differences from peripheral blood T cells. There was an increase in melanomaassociated antigen recognized by T cells (MART-1)-specific T cells in tumors undergoing regression after vaccination compared with T cells derived from melanoma patients not treated with vaccine. There was also a significant decrease in Treg and Ts cells in injected lesions compared with noninjected lesions in the same and different melanoma patients. Similarly MDSC were increased in melanoma lesions but underwent a significant decrease only in vaccinated lesions.

CONCLUSIONS

Melanoma patients present with elevated levels of Tregs, Ts, and MDSC within established tumors. Direct injection of Oncovex(GM-CSF) induces local and systemic antigen-specific T cell responses and decreases Treg, Ts, and MDSC in patients exhibiting therapeutic responses.

New platinum-oxicam complexes as anti-cancer drugs. Synthesis, characterization, release studies from smart hydrogels, evaluation of reactivity with selected proteins and cytotoxic activity in vitro

The reaction of aqueous cis-[Pt(NH(3))(2)(H(2)O)(2)](NO(3))(2) with Na(+)HMEL(-) (H(2)MEL, meloxicam, 4-hydroxy-2-methyl-N-(5-methyl-1,3-thiazol-2-yl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide), and Na(+)HISO(-) (H(2)ISO, isoxicam, 4-hydroxy-2-methyl-N-(5-methylisoxazol-3-yl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide) at pH 7 produced micro-crystalline cis-[Pt(NH(3))(2)(N(1')-HMEL)(2)], 5 and cis-[Pt(NH(3))(2)(N(1')-HISO)(2)], 6. The X-ray diffraction structure of 5 shows two HMEL(-) anions donating through the thiazole nitrogen atoms and adopting a head-to-tail (HT) conformation. The (1)H NMR spectrum for 5 from DMSO-d(6) shows inertness of the complex up to at least 24h. Delivery studies for 5 and 6 from vinyl hydrogel based on L-phenylalanine (pH 6.5, 25 degrees C) show that concentrations of complexes ranging between 2.5 and 5 microM can be reached after a day. Compounds 5 and 6 show strong anti-proliferative effects on CH1 cells (ovarian carcinoma, human) in vitro, IC(50) values being 0.60 and 0.37 microM, respectively (0.16 microM for reference, cis-diamminodichloridoplatinum(II), cisplatin). ESI-MS measurements clearly documented that both 5 and 6 form adducts with the three model proteins ubiquitin (UBI), cytochrome c (CYT C) and superoxide dismutase (SOD), the HISO(-) complex being significantly more effective than the HMEL(-) one. Density functional methods help in finding rationale for the easiest dissociation of Pt-H(2)ISO/HISO bonds when compared to the Pt-N(1)(')-H(2)MEL/N(1)(')-HMEL linkages.

Progressive cellular response in the lamina propria of the colorectal adenoma-carcinoma sequence

AIMS

The lamina propria is inevitably involved in epithelial transformation. The aim was to evaluate the dynamic cellular changes in the tumour lamina propria throughout the colorectal adenoma-carcinoma sequence.

METHODS AND RESULTS

Using immunohistochemistry and double immunohistochemistry, we examined lamina propria cellular changes in 41 colorectal adenomas, 25 colorectal cancers and 15 control tissues. The results showed that the proliferation labelling index in lamina propria cells began to increase in the precancerous lesions (adenomas) and became even higher in the colorectal cancers; these proliferative cells were primarily identified as myofibroblasts and lymphocytes. Phenotypic analysis revealed gradually increasing lymphocytic infiltration in both the lamina propria and adenomatous epithelium, as well as myofibroblasts in the lamina propria. However, the intraepithelial macrophage density also showed a tendency to increase gradually. Furthermore, cyclooxygenase-2-expressing cell density and microvessel density gradually increased in the tumour lamina propria throughout the adenoma-carcinoma sequence.

CONCLUSIONS

Progressive cellular responses in the lamina propria could be involved in the adenoma-carcinoma transition.

Invariant natural killer T cells and immunotherapy of cancer

Invariant CD1d restricted natural killer T (iNKT) cells are regulatory cells that express a canonical TCR-Valpha-chain (Valpha24.Jalpha18 in humans and Valpha14.Jalpha18 in mice) which recognizes glycolipid antigens presented by the monomorphic CD1d molecule. They can secrete a wide variety of both pro-inflammatory and anti-inflammatory cytokines very swiftly upon their activation. Evidence for the significance of iNKT cells in human cancer has been ambiguous. Still, the (pre-)clinical findings reviewed here, provide evidence for a distinct contribution of iNKT cells to natural anti-tumor immune responses in humans. Furthermore, clinical phase I studies that are discussed here have revealed that the infusion of cancer patients with ligand-loaded dendritic cells or cultured iNKT cells is well tolerated. We thus underscore the potential of iNKT cell based immunotherapy in conjunction with established modalities such as surgery and radiotherapy, as adjuvant therapy against carcinomas.

New cellular tools reveal complex epithelial-mesenchymal interactions in hepatocarcinogenesis

To enable detailed analyses of cell interactions in tumour development, new epithelial and mesenchymal cell lines were established from human hepatocellular carcinoma by spontaneous outgrowth in culture. We obtained several hepatocarcinoma (HCC)-, B-lymphoblastoid (BLC)-, and myofibroblastoid (MF)-lines from seven cases. In-depth characterisation included cell kinetics, genotype, tumourigenicity, expression of cell-type specific markers, and proteome patterns. Many functions of the cells of origin were found to be preserved. We studied the impact of the mesenchymal lines on hepatocarcinogenesis by in vitro assays. BLC- and MF-supernatants strongly increased the DNA replication of premalignant hepatocytes. The stimulation by MF-lines was mainly attributed to HGF secretion. In HCC-cells, MF-supernatant had only minor effects on cell growth but enhanced migration. MF-lines also stimulated neoangiogenesis through vEGF release. BLC-supernatant dramatically induced death of HCC-cells, which could be largely abrogated by preincubating the supernatant with TNFβ-antiserum. Thus, the new cell lines reveal stage-specific stimulatory and inhibitory interactions between mesenchymal and epithelial tumour cells. In conclusion, the new cell lines provide unique tools to analyse essential components of the complex interplay between the microenvironment and the developing liver cancer, and to identify factors affecting proliferation, migration and death of tumour cells, neoangiogenesis, and outgrowth of additional malignancy.

Profiling of genetic variations in inflammation pathway genes in relation to bladder cancer predisposition

PURPOSE

Compelling evidence has indicated that inflammation plays an important role in cancer development. We sought to test the hypothesis that common sequence variants in the inflammation pathway modulate bladder cancer risk.

EXPERIMENTAL DESIGN

We genotyped 59 potentially functional single nucleotide polymorphisms from 35 candidate inflammation genes in a case-control study including 635 Caucasian bladder cancer patients and 635 matched controls.

RESULTS

The most significant finding was in the 3'-untranslated region of PTGS2 (exon10+837T>C, rs5275), which was associated with a significantly reduced risk (odds ratio, 0.68; 95% confidence interval, 0.54-0.87; P=0.002) and remained significant after multiple comparison adjustment. Consistently, the most common PTGS2 haplotype containing the common allele of exon10+837T>C was associated with a significantly increased risk (odds ratio, 1.27; 95% confidence interval, 1.06-1.52; P=0.008). In contrast, the haplotypes containing at least one variant allele of exon10+837T>C were all associated with a decreased risk. In a combined analysis to assess the cumulative effects of inflammation single nucleotide polymorphisms on bladder cancer risk, we found that in the anti-inflammation pathway, but not in the proinflammation pathway, when compared with individuals with a few adverse alleles, individuals with more adverse alleles had a significantly increased risk in a dose-dependent manner (P(trend)=0.012). To further elucidate the functional mechanism of these associations, we redefined the adverse alleles based on literature-reported functional results and found that individuals with a higher number of inflammation-enhancing alleles in the anti-inflammation pathway exhibited a greater bladder cancer risk.

CONCLUSIONS

Our results strongly suggest that common variants in inflammation genes affect bladder cancer susceptibility individually and jointly.

Tumor-infiltrated immune response correlates with alterations in the apoptotic and cell cycle pathways in Hodgkin and Reed-Sternberg cells

PURPOSE

To analyze tumor-microenvironment relationships in Hodgkin lymphoma (HL) as potential determinants in the decision-making process related to the alterations in cell cycle and apoptotic pathways of Hodgkin/Reed-Sternberg (H/RS) cells.

EXPERIMENTAL DESIGN

Based on a cohort of 257 classic HL patients, we carried out a global descriptive correlational analysis and logistic regression study to identify tumor-infiltrated immune cell rate in HL that could be interconnected with genes involved in the regulation of apoptotic/proliferative pathways in H/RS cells.

RESULTS

Our results reveal the existence of a connection between the reactive microenvironment and molecular changes in apoptotic/proliferative pathways in H/RS cells. A lesser incidence of infiltrated cytotoxic cells in the tumor (CD8(+) T lymphocytes, CD57(+) natural killer, and granzyme B(+) cells) was associated with overexpression of antiapoptotic proteins (Bcl-X(L), survivin, caspase-3, and nuclear factor-kappaB) in tumoral cells. Increased incidence of general infiltrated immune cells, such as CD4(+) T lymphocytes, CD57(+) natural killer cells, activated CTL, and dendritic cells, in the microenvironment of the tumor was associated with increased growth fraction of tumoral cells, including G(1)-S checkpoint (cyclin D and cyclin E) and tumor suppressor pathways (p16 and SKP2), and with the presence of EBV (signal transducers and activators of transcription 1 and 3 expression; STAT1/STAT3).

CONCLUSIONS

A lower level of cytotoxic cells correlated with an increase of antiapoptotic mechanisms in H/RS cells, whereas the global infiltrated immune population correlated with the growth fraction of the tumor. Our collective data suggest a causal relationship between infiltrated immune response and concurrent changes of the different proliferative checkpoints, tumor suppressor, and apoptotic pathways of H/RS cells in HL.

Expansion of human T regulatory type 1 cells in the microenvironment of cyclooxygenase 2 overexpressing head and neck squamous cell carcinoma

Cyclooxygenase 2 (COX-2) overexpression and production of prostaglandin E(2) (PGE(2)) by head and neck squamous cell carcinomas (HNSCC) induce type 1 regulatory T (Tr1) cells and contribute to carcinogenesis by creating a tolerogenic milieu. To test this hypothesis, CD4(+)CD25(-) T cells obtained from the peripheral blood of 10 normal donors were cocultured with autologous dendritic cells, irradiated HNSCC cells and cytokines, interleukin 2 (IL-2), IL-10, and IL-15. HNSCC cells were either COX-2 negative, constitutively expressed COX-2, were transfected with COX-2, or had COX-2 expression knocked down by small interfering RNA. Other modifications included coculture plus or minus the COX-inhibitor, Diclofenac, or synthetic PGE(2) in the absence of HNSCC. Lymphocytes proliferating in 10-day cocultures were phenotyped by flow cytometry, studied for cytokine production by ELISA and for suppressor function in CFSE inhibition assays plus or minus anti-IL-10 or anti-transforming growth factor-beta(1) (TGF-beta(1)) monoclonal antibodies (mAb). COX-2(+) HNSCC or exogenous PGE(2) induced outgrowth of Tr1 cells with the CD3(+)CD4(+)CD25(-)IL2Rbeta(+)IL2Rgamma(+)FoxP3(+)CTLA-4(+)IL-10(+)TGF-beta(1)(+)IL-4(-) phenotype and high suppressor functions (range, 46-68%). Small interfering RNA knockout of COX-2 gene in HNSCC led to outgrowth of lymphocytes with decreased IL2Rgamma (P = 0.0001), FoxP3 (P = 0.05), and IL-10 (P = 0.035) expression and low suppressor activity (range, 26-34%). Whereas COX-2(+) cocultures contained IL-10 and TGF-beta(1) (medians, 615 and 824 pg/mL), cytokine levels were decreased (P < 0.0001) in COX-2(-) cocultures. Inhibition of COX-2 enzymatic activity in HNSCC abrogated outgrowth of Tr1 cells. Neutralizing mAbs to IL-10 and/or TGF-beta(1) abolished Tr1-mediated suppression. COX-2 overexpression in HNSCC plays a major role in the induction of Tr1 cells in the tumor microenvironment.

Immune signatures of murine and human cancers reveal unique mechanisms of tumor escape and new targets for cancer immunotherapy

PURPOSE

Despite lymphocyte infiltration of tumors and the activation of tumor-draining lymph nodes, malignant tumors are able to "escape" from both innate and adaptive immune responses. For immunotherapy to be successful, it must reverse these escape mechanisms, which necessitates explicit and tumor-specific elucidation of tumor escape strategies.

RESEARCH DESIGN

To identify relevant escape mechanisms in murine tumors and in two corresponding human cancers, real-time reverse transcription-PCR was used to measure a panel of genes associated with T-cell activation and inhibition pathways.

RESULTS

Comparative analysis of the expression levels of these immunomodulatory genes showed astonishing similarities in expression patterns between murine and human breast cancers but profound variability in the expression of immunomodulatory genes in colorectal cancers. For human ductal adenocarcinoma of the breast, down-regulation of dendritic cell maturation marker CD83 and T-cell activation gene CD28 was observed as well as a notable increase in the expression of the immunoinhibitory gene B7-H4. By contrast, colorectal adenocarcinoma cases showed high variability in tumor escape mechanisms, indicating a need to produce immune signatures for individual patients to identify appropriate immunotherapeutic targets.

CONCLUSIONS

These results show that certain tumors, such as ductal carcinoma of the breast, show consistent immunologic abnormalities that can be used as targets for immunotherapy. These findings also show the importance and feasibility of determining the immune signatures of patients' tumors to select appropriate immunotherapeutic strategies. Ultimately, these results advocate for the determination of immune signatures as part of the customary repertoire of clinical diagnostics for cancer.

Reduced expression of microenvironmental Th1 cytokines accompanies adenomas-carcinomas sequence of colorectum

Cytokines have been suggested to be key factors in modulating immune response against tumorigenesis in the microenvironment. Therefore, characterization of cytokine expression along the colorectal adenoma-carcinoma sequence may add important information for understanding the immune-related mechanisms of the development of colorectal carcinoma (CRC). In this study, biopsies from 32 patients with colorectal adenoma (CRA), 20 patients with CRC and 18 healthy controls were examined. Cytokine gene expressions of interleukin-4 (IL-4), IL-10, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and its upstream inducers (IL-12A and IL-18) were measured at messenger RNA (mRNA) level with quantitative real-time PCR (Q-PCR). Cytokine expressing cells were characterized using immunohistochemistry (IHC). A distinct different cytokine profile between adenoma and CRC was observed: the Th1 cytokines (IFN-gamma, TNF-alpha, IL-12A and IL-18) were increased in local tissues of CRA and decreased in CRC. Consistent with the quantitative cytokine data, IHC examinations revealed slightly increased densities of Th1 cytokine-expressing cells in CRA and a remarkably decreased density of the Th1 cells in CRC. In CRA, the cytokine-expressing cells were highly polarized to the subepithelial stroma while the cells were evenly distributed through the stroma in CRC. In conclusion, distinct changes in the Th1 cytokine profile appear along the colorectal adenoma-carcinoma sequence. This may reflect a change in the host immune regulatory function in the adenoma-carcinoma sequence.

Real and artificial immune systems: computing the state of the body

Here I present the idea that the immune system uses a computational strategy to carry out its many functions in protecting and maintaining the body. Along the way, I define the concepts of computation, Turing machines and system states. I attempt to show that reframing our view of the immune system in computational terms is worth our while.

The role of death receptor ligands in shaping tumor microenvironment

Death receptor ligands (FasL, TRAIL) activate apoptosis in cells expressing the cognate receptors. Evidence suggests that these ligands also deliver pro-inflammatory signals. In the tumor microenvironment, "Fas counterattack" mounted by tumors against immune cells is mediated by tumor-associated FasL. But death ligands crosslinking their receptors also induce inhibition of apoptosis and activation of the transcription factor, NFkappaB, with a subsequent burst of pro-inflammatory cytokine production and tumor growth promotion. NFkappaB, a key link between inflammation and cancer, regulates dual activities of death ligands, depending on molecular signals in the tumor microenvironment. This paper focuses on death ligands as an example of the extensive repertoire of strategies devised by tumors for escape from immune control.

TGF-beta: a mobile purveyor of immune privilege

Functionally barricaded immune responses or sites of immune privilege are no longer considered dependent on specific anatomical considerations, but rather, they can develop in any location where immunoregulatory cells congregate and express or release products capable of deviating the host response to foreign antigens. Among the pivotal molecules involved in orchestrating these ectopic sites of immune suppression is transforming growth factor-beta (TGF-beta), a secreted and cell-associated polypeptide with a multiplicity of actions in innate and adaptive immunity. While beneficial in initiating and controlling immune responses and maintaining immune homeostasis, immunosuppressive pathways mediated by TGF-beta may obscure immune surveillance mechanisms, resulting in failure to recognize or respond adequately to self, foreign, or tumor-associated antigens. CD4+CD25+Foxp3+ regulatory T cells represent a dominant purveyor of TGF-beta-mediated suppression and are found in infiltrating tumors and other sites of immune privilege, where they influence CD8+ T cells; CD4+ T-helper (Th)1, Th2, and Th17 cells; natural killer cells; and cells of myeloid lineage to choreograph and/or muck up host defense. Defining the cellular sources, mechanisms of action, and networking that distinguish the dynamic establishment of localized immune privilege is vital for developing strategic approaches to diminish or to embellish these tolerogenic events for therapeutic benefit.

In situ analysis of FOXP3+ regulatory T cells in human colorectal cancer

The immune system spontaneously responds to tumor-associated antigens in peripheral blood of colorectal cancer (CRC) patients. Regulatory T cells (Treg) are suspected of influencing the interaction between the tumor and immune system and thus the course of malignant diseases. However, the function of Tregs in the development of T cell responses and on the clinical course of CRC is not clear. We analyzed Treg infiltration (FOXP3 staining) in situ in 40 CRC patients and investigated whether there is a correlation to disease stage, systemic T cell response, and survival. Treg infiltration was significantly higher in CRC than in healthy colon. Stromal Treg infiltration was significantly higher than epithelial infiltration in CRC. Furthermore, Treg infiltration in the tumor was significantly higher in limited disease than in metastatic CRC. The average Treg infiltration rate in the tumor was non-significantly higher in patients without systemic TAA-specific T cell response. Survival did not differ between patients with high Treg infiltration and those with low Treg infiltration. In conclusion, a direct link between Treg infiltration in the tumor and the development of a systemic T cell response in CRC cannot be proven. However, local Treg infiltration was significantly higher in limited disease, in which a systemic TAA-directed T cell responses is less frequently observed.