Lymphocyte apoptosis induced by Fas ligand- expressing ovarian carcinoma cells. Implications for altered expression of T cell receptor in tumor-associated lymphocytes

FASLG as a Key Member of Necroptosis Participats in Acute Myocardial Infarction by Regulating Immune Infiltration

Background

Acute myocardial infarction (AMI) is a major cause of human health risk. Necroptosis is a newly and recently reported mode of cell death, whose role in AMI has not been fully elucidated. This study aimed to search for necroptosis biomarkers associated with the occurrence of AMI and to explore their possible molecular mechanisms through bioinformatics analysis.

Methods

The dataset GSE48060 was used to perform weighted gene co-expression network analysis (WGCNA) and differential analysis. Key modules, differential genes, and necroptosis-related genes (NRGs) were intersected to obtain candidate biomarkers. Groups were classified and differentially analyzed according to the expression of the key biomarker. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, gene set enrichment analysis (GSEA), and construction of protein-protein interaction (PPI) networks are performed on differentially expressed genes (DEGs). Finally, CIBERSORT was used to assess immune cell infiltration in AMI and the correlation of key biomarkers with immune cells. Immune cell infiltration analysis revealed the correlation between FASLG and multiple screened immune cells.

Results

WGCNA determined that the MEsaddlebrown module was the most significantly associated with AMI. Intersecting it with DEGs as well as NRGs, we obtained two key genes, FASLG and IFNG. But only FASLG showed statistically significant differences between the AMI group and the normal control group. Further analysis suggested that the down-regulation of FASLG may exert its function through the regulation of the central genes CD247 and YES1. Furthermore, FASLG was positively correlated with T-cell CD4 memory activation and T-cell gamma delta, and negatively correlated with macrophage M0.

Conclusion

In conclusion, FASLG and its regulatory genes CD247 and YES1 might be involved in the development of AMI by regulating immune cell infiltration. FASLG might be a potential biomarker for AMI and provides a new direction for the diagnosis of AMI.

Exploitation of CD3ζ to enhance TCR expression levels and antigen-specific T cell function

The expression levels of TCRs on the surface of human T cells define the avidity of TCR-HLA/peptide interactions. In this study, we have explored which components of the TCR-CD3 complex are involved in determining the surface expression levels of TCRs in primary human T cells. The results show that there is a surplus of endogenous TCR α/β chains that can be mobilised by providing T cells with additional CD3γ,δ,ε,ζ chains, which leads to a 5-fold increase in TCR α/β surface expression. The analysis of individual CD3 chains revealed that provision of additional ζ chain alone was sufficient to achieve a 3-fold increase in endogenous TCR expression. Similarly, CD3ζ also limits the expression levels of exogenous TCRs transduced into primary human T cells. Interestingly, transduction with TCR plus CD3ζ not only increased surface expression of the introduced TCR, but it also reduced mispairing with endogenous TCR chains, resulting in improved antigen-specific function. TCR reconstitution experiments in HEK293T cells that do not express endogenous TCR or CD3 showed that TCRα/β and all four CD3 chains were required for optimal surface expression, while in the absence of CD3ζ the TCR expression was reduced by 50%. Together, the data show that CD3ζ is a key regulator of TCR expression levels in human T cells, and that gene transfer of exogenous TCR plus CD3ζ improved TCR surface expression, reduced TCR mispairing and increased antigen-specific function.

Prognostic value of pretreatment lymphocyte percentage in oral cancer: A prospective cohort study

OBJECTIVE

To assess the prognostic role of pretreatment lymphocyte percentage (LY%) for patients with oral squamous cell carcinoma (OSCC).

METHODS

A large-scale prospective cohort study between July 2002 and March 2021 was conducted. Propensity score-matched (PSM) analysis and inverse probability of treatment weighting (IPTW) analysis were performed to adjust for potential confounders. Using random survival forest (RSF), the relative importance of pretreatment LY% in prognosis prediction was also assessed.

RESULTS

A total of 743 patients were enrolled and followed up (median: 2.75 years, interquartile range: 1.25-4.42 years). A high pretreatment LY% was significantly associated with better disease-specific survival of patients with OSCC (Hazard ratio [HR] = 0.60, 95% confidence interval [CI]: 0.42, 0.84). The same tendency was observed in PSM (HR = 0.57, 95% CI: 0.38, 0.85) and IPTW analysis (HR = 0.57, 95% CI: 0.40, 0.82). RSF showed that LY% ranked the fifth among importance ranking of all prognostic factors.

CONCLUSION

Pretreatment LY% showed a moderate predictive ability, suggesting it might be a valuable tool to predict prognosis for patients with OSCC.

The anti-ovarian carcinoma activity of L-amino acid oxidase from Crotalus adamanteus venom in vivo and in vitro

Snake venom L-Amino-acid oxidase (svLAAO) has become a critical research target in molecular biology and medical science since its widespread presence and diverse biological roles, including antitumor application. Our research confirmed that Crotalus adamanteus (C. adamanteus) venom LAAO exhibited potential anti-ovarian cancer activity both in vivo and in vitro. C. adamanteus venom LAAO significantly reduced viability of ovarian cancer cells and caused morphological changes that preceded cell death. The results of molecular biology experiments showed that C. adamanteus venom LAAO caused expression changes of genes related to apoptotic pathways either intrinsically or extrinsically in ovarian cancer cells. Animal experiments and histological analysis also proved that C. adamanteus venom LAAO could effectively inhibit the tissue damage caused by ovarian cancer, and animals treated with C. adamanteus venom LAAO showed higher survival time. Catalase blocked the major apoptosis induction of C. adamanteus venom LAAO on ovarian cancer cells, suggesting that the cytotoxicity of C. adamanteus venom LAAO on ovarian cancer cells was mainly mediated by H₂O₂. These results infer that C. adamanteus venom LAAO will have some advantages in new drug research and antitumor drug development in future.

The Proposition of the Pulmonary Route as an Attractive Drug Delivery Approach of Nano-Based Immune Therapies and Cancer Vaccines to Treat Lung Tumors

Lung cancer is the leading cause of cancer related deaths globally, making it a major health concern. The lung’s permissive rich microenvironment is ideal for supporting outgrowth of disseminated tumors from pre-existing extra-pulmonary malignancies usually resulting in high mortality. Tumors occurring in the lungs are difficult to treat, necessitating the need for the development of advanced treatment modalities against primary tumors and secondary lung metastasis. In this review, we explore the pulmonary route as an attractive drug delivery approach to treat lung tumors. We also discuss the potential of pulmonary delivery of cancer vaccine vectors to induce mucosal immunity capable of preventing the seeding of tumors in the lung.

Immunotyping in tubo-ovarian high-grade serous carcinoma by PD-L1 and CD8+ T-lymphocytes predicts disease-free survival

PD-L1 immune checkpoint inhibitor expression was evaluated in high-grade serous carcinoma (HGSC) ovary in the context of the overall immune landscape to determine its prognostic value. Consecutive cases of HGSC, 50 who underwent upfront surgery followed by adjuvant chemotherapy (HGSC-U) and 50 who underwent neoadjuvant chemotherapy (NACT) followed by interval debulking surgery (HGSC-PC) were selected. In HGSC-PC cases, the pre-NACT ascitic fluid cell blocks were included. Tumor-infiltrating lymphocytes (TILs) were scored, hotspots chosen for tissue microarray construction and immunohistochemistry performed and scored for CD4 and CD8 lymphocyte subsets, CD68+ tumor-associated macrophages (TAMs), PD-1 and PD-L1 expression. HGSC-post-chemotherapy showed increased TILs, predominantly CD8+T-lymphocytes, compared to HGSC-U. HGSC showed PD-L1 expression on tumor cells and/or TAMs in 60% cases with a linear correlation to CD4+, CD8+ TIL levels. Concordant PD-L1 expression was seen in matched pre- and post-NACT tumor cells. HGSC-PC showed higher expression of PD-L1. There was no association of PD-L1 cumulative proportion score or tumor cell score with outcome. Taking a cutoff for PD-L1 CPS at 10%, immunotype I (PD-L1+/CD-8+), corresponding to tumors with adaptive immune evasion, showed worst disease-free survival compared to all other immunotypes (p = 0.03) and was more significant (p = 0.01) when compared to immunotype III (PD-L1+/CD8-). Immunotyping based on PD-L1/CD8+ expression correlates to prognosis and outcome.

Defects at the Posttranscriptional Level Account for the Low TCRζ Chain Expression Detected in Gastric Cancer Independently of Caspase-3 Activity

Background

Reduced TCRζ chain surface has been reported in T cells from patients with different inflammatory conditions and cancer. However, the causes of this diminished expression in cancer remain elusive.

Methods

T cell-enriched populations of blood or tissue (tumoral and nontumoral) origin from 44 patients with gastric adenocarcinoma and 33 healthy subjects were obtained. Samples were subjected to cytofluorimetry, Western blot analysis, TCRζ cDNA sequencing experiments, measurement of TCRζ mRNA levels, and caspase-3 activity assays.

Results

Cytofluorimetry revealed a decreased TCRζ expression in T cells of patients, assessed either as percentage of cells expressing this chain (blood: control subjects 99.8 ± 0.1%, patients 98.8 ± 1.1%P < 0.001; tissue: control subjects 96.7 ± 0.9%, patients tumoral tissue 67.9 ± 27.0%, patients nontumoral tissue 82.8 ± 12.6%, P = 0.019) or mean fluorescence intensity (MFI) value (blood: control subjects 102.2 ± 26.0; patients 58.0 ± 12.3, P = 0.001; tissue: control subjects 99.4 ± 21.4; patients tumoral tissue 41.6 ± 21.4; patients nontumoral tissue 62.3 ± 16.6, P = 0.001). Other chains pertaining to the TCR-CD3 complex (CD3ε) showed no significant differences (MFI values). Subsequent TCRζ cDNA sequencing experiments or measurements of TCRζ mRNA levels disclosed no differences between patients and control subjects. Evaluation of caspase-3 activity showed higher levels in T cell extracts of patients, and this activity could be decreased by 70% with the use of the inhibitor Ac-DEVD-FMK, although CD3ζ expression levels did not recover.

Conclusions

These results further place the defect responsible for the low TCRζ expression in cancer at the posttranscriptional level and suggests contrary to what has been proposed in other pathologies that elevated caspase-3 activity is not the causative agent.

Antitumour dendritic cell vaccination in a priming and boosting approach

Mobilizing antitumour immunity through vaccination potentially constitutes a powerful anticancer strategy but has not yet provided robust clinical benefits in large patient populations. Although major hurdles still exist, we believe that currently available strategies for vaccines that target dendritic cells or use them to present antitumour antigens could be integrated into existing clinical practice using prime-boost approaches. In the priming phase, these approaches capitalize on either standard treatment modalities to trigger in situ vaccination and release tumour antigens or vaccination with dendritic cells loaded with tumour lysates or patient-specific neoantigens. In a second boost phase, personalized synthetic vaccines specifically boost T cells that were triggered during the priming phase. This immunotherapy approach has been enabled by the substantial recent improvements in dendritic cell vaccines. In this Perspective, we discuss these improvements, highlight how the prime-boost approach can be translated into clinical practice and provide solutions for various anticipated hurdles.

Myeloid Cell-Derived Arginase in Cancer Immune Response

Amino acid metabolism is a critical regulator of the immune response, and its modulating becomes a promising approach in various forms of immunotherapy. Insufficient concentrations of essential amino acids restrict T-cells activation and proliferation. However, only arginases, that degrade L-arginine, as well as enzymes that hydrolyze L-tryptophan are substantially increased in cancer. Two arginase isoforms, ARG1 and ARG2, have been found to be present in tumors and their increased activity usually correlates with more advanced disease and worse clinical prognosis. Nearly all types of myeloid cells were reported to produce arginases and the increased numbers of various populations of myeloid-derived suppressor cells and macrophages correlate with inferior clinical outcomes of cancer patients. Here, we describe the role of arginases produced by myeloid cells in regulating various populations of immune cells, discuss molecular mechanisms of immunoregulatory processes involving L-arginine metabolism and outline therapeutic approaches to mitigate the negative effects of arginases on antitumor immune response. Development of potent arginase inhibitors, with improved pharmacokinetic properties, may lead to the elaboration of novel therapeutic strategies based on targeting immunoregulatory pathways controlled by L-arginine degradation.

CD247 expression is associated with differentiation and classification in ovarian cancer

Ovarian cancer (OC) is one of the most common malignant tumors in female reproductive system and most OC cases are diagnosed at an advanced stage with the overall 5-year survival rate below 40%. The function of CD247 enhances T-cell antigen receptor (TCR) signaling cascade and it is necessary for assembling of the TCR/CD3 complex on the surface of T lymphocytes. It is well established that defective CD247 function leads to impaired activation of T cells upon engagement of the TCR.Flow cytometry was used to examine the difference of CD247 T lymphocyte between the OC and ovarian cyst, immunohistochemistry analysis was used to investigate the correlation between CD247 expression and clinicopathologic features of epithelial OC patients.Our study showed that the expression of CD247 in peripheral blood lymphocytes from patients with OC is decreased compared with ovarian cyst patients and the expression of CD247 in tumor infiltrating lymphocytes with cancer tissue is decreased compared with adjacent tissues. We showed that abnormal expression of CD247 was related with differentiation and classification in OC.Our findings suggested that CD247-targeted treatment could be used as a potential therapeutic strategy for OC.

The role of the oncogenic Rab35 in cancer invasion, metastasis, and immune evasion, especially in leukemia

The study of cancer has allowed researchers to describe some biological characteristics that tumor cells acquire during their development, known as the “hallmarks of cancer” but more research is needed to expand our knowledge about cancer biology and to generate new strategies of treatment. The role that RabGTPases might play in some hallmarks of cancer represents interesting areas of study since these proteins are frequently altered in cancer. However, their participation is not well known. Recently, Rab35was recognized as an oncogenic RabGTPase and and because of its association with different cellular functions, distinctly important in immune cells, a possible role of Rab35 in leukemia can be suggested. Nevertheless, the involvement of Rab35 in cancer remains poorly understood and its possible specific role in leukemia remains unknown. In this review, we analyze general aspects of the participation of RabGTPases in cancer, and especially, the plausible role of Rab35 in leukemia.

Tumor Infiltrating Lymphocytes in Uveal Melanoma: A Link with Clinical Behavior?

Experimental and clinical evidence indicate that immunological mechanisms might be important in the clinical course of uveal malignant melanoma (UMM). We analyzed the amount and phenotype of tumor infiltrating lymphocytes (TIL) and the expression of the apoptosis-inducing molecule Fas and its ligand, FasL, on tumor cells and TIL in a selected series of UMM with the aim to establish if a correlation between their expression and the clinical behavior of UMM exists. TIL phenotype and Fas/FasL expression were evaluated by immunohistochemistry in 61 cases of formalin-fixed, paraffin-embedded UMM. Results were compared with the follow-up data of patients. Most of the UMM showed a prevalence of CD8+ CD3+ T lymphocytes, or CD4+ and CD8+ cells in equal amounts. UMM showed a variable expression of FasL, ranging from 0 to > 40% of neoplastic cells. Fas was always expressed in TIL, although with a variable extent. A subgroup of UMM showed in TIL a strongly reduced or even absent expression of TCR ζ-chain, involved in activation of T-lymphocytes. This subgroup was characterized by a worse outcome. We hypothesized that an impaired cytotoxic immune response due to the loss of the ζ-chain expression plays a primary role in the biological course of UMM. Our results indicate that the overcoming of the impairment of TCR function may represent a prerequisite for the development of new therapeutic strategies for managing UMM, suggesting that elimination of tumor cells may be possible by activation of cytotoxic cells present within ocular melanomas.

Clinicopathological significance of Fas and Fas ligand expressions in esophageal cancer

Esophageal carcinomas have recently been shown to express Fas ligand (FasL) and down-regulate Fas to escape from host immune surveillance. However, the prognostic importance of Fas/FasL and their correlation with clinicopathological characteristics are yet to be delineated in this highly malignant carcinoma. Specimens from 106 esophageal squamous cell carcinoma patients were used for immuno-histochemical evaluation of Fas, FasL, and CD8 expressions. Fifty-two (49%) and 34 (32%) patients were positive for FasL and Fas, respectively. There were no associations between FasL expression and clinicopathological characteristics except lymph vessel invasion. Strong FasL expression correlated with significant (P < 0.001) decrease in tumor nest CD81 cells. However, neither FasL nor CD81 had any impact on patient survival. Strong Fas expression was correlated with depth of invasion (40.3% in pT1, T2 versus 20.5% in pT3, T4; P5 0.0308), histological differentiation (45.7% in well versus 25.4% in nonwell; P < 0.05), and lymph node metastasis (22.6% in positive versus 45.5% in negative; P < 0.01). Fas expression was one of the independent favorable prognosticators for patients' survival (risk ratio, 3.26; P < 0.01) in esophageal SCC. Fas expression was an independent prognosticator for recurrencefree survival, whereas FasL expression did not influence the survival in esophageal squamous cell carcinoma. Down-regulation of tumor Fas may be the hallmark of immune privilege for the tumor, thus causing the patients' poorer outcome. Tumor FasL may counterattack the host immune cells to such an extent that the prognosis is not affected.

Association of the polymorphisms in the Fas/FasL promoter regions with cancer susceptibility: a systematic review and meta-analysis of 52 studies

Fas and its ligand (FasL) play an important role in apoptosis and carcinogenesis. Therefore, the potential association of polymorphisms in the Fas (-670A>G, rs1800682; -1377G>A, rs2234767) and FasL (-844C>T, rs763110) with cancer risk has been widely investigated. However, all the currently available results are not always consistent. In this work, we performed a meta-analysis to further determine whether carriers of the polymorphisms in Fas and FasL of interest could confer an altered susceptibility to cancer. All relevant data were retrieved by PubMed and Web of Science, and 52 eligible studies were chosen for this meta-analysis. There was no association of the Fas -670A>G polymorphism with cancer risk in the pooled data. For the Fas -1377G>A and FasL -844C>T polymorphisms, results revealed that the homozygotes of -1377A and -844C were associated with elevated risk of cancer as a whole. Further stratified analysis indicated markedly increased risk for developing breast cancer, gastric cancer, and esophageal cancer, in particular in Asian population. We conclude that carriers of the Fas-1377A and the FasL -844C are more susceptible to the majority of cancers than non-carriers.

A Phase I vaccine trial using dendritic cells pulsed with autologous oxidized lysate for recurrent ovarian cancer

Purpose

Ovarian cancer, like most solid tumors, is in dire need of effective therapies. The significance of this trial lies in its promise to spearhead the development of combination immunotherapy and to introduce novel approaches to therapeutic immunomodulation, which could enable otherwise ineffective vaccines to achieve clinical efficacy.

Rationale

Tumor-infiltrating T cells have been associated with improved outcome in ovarian cancer, suggesting that activation of antitumor immunity will improve survival. However, molecularly defined vaccines have been generally disappointing. Cancer vaccines elicit a modest frequency of low-to-moderate avidity tumor-specific T-cells, but powerful tumor barriers dampen the engraftment, expansion and function of these effector T-cells in the tumor, thus preventing them from reaching their full therapeutic potential. Our work has identified two important barriers in the tumor microenvironment: the blood-tumor barrier, which prevents homing of effector T cells, and T regulatory cells, which inactivate effector T cells. We hypothesize that cancer vaccine therapy will benefit from combinations that attenuate these two barrier mechanisms.

Design

We propose a three-cohort sequential study to investigate a combinatorial approach of a new dendritic cell (DC) vaccine pulsed with autologous whole tumor oxidized lysate, in combination with antiangiogenesis therapy (bevacizumab) and metronomic cyclophosphamide, which impacts Treg cells.

Innovation

This study uses a novel autologous tumor vaccine developed with 4-day DCs pulsed with oxidized lysate to elicit antitumor response. Furthermore, the combination of bevacizumab with a whole tumor antigen vaccine has not been tested in the clinic. Finally the combination of bevacizumab and metronomic cyclophosphamide in immunotherapy is novel.

Functional polymorphisms in FAS and FASL contribute to risk of squamous cell carcinoma of the larynx and hypopharynx in a Chinese population

Accumulating evidences indicate that the functional FAS-1377G>A, -670A>G and FASL-844T>C polymorphisms affect the risk of several kinds of cancers. However, their roles in the development of larynx and hypopharynx squamous cell carcinoma (SCC) were still unknown in the Chinese. In the current study, we examined whether these functional genetic variants were associated with the risk of larynx and hypopharynx squamous SCC in a Han Chinese population. The FAS and FASL polymorphisms were genotyped in 300 patients with laryngeal and hypopharyngeal SCC and 300 control subjects by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Logistic regression analysis revealed that subjects carrying the FASL-844CT or TT genotype had a significantly decreased risk of developing laryngeal and hypopharyngeal SCC [odds ratio (OR)=0.69; 95% confidence interval (CI)=0.51-0.93; P=0.016; or, OR=0.41; 95% CI=0.20-0.86; P=0.009] compared with those carrying the CC genotype. Joint gene-smoking and gene-drinking effects were also observed, with the OR of CC genotype for smokers or drinkers were 5.15 (95%CI=3.24-8.97) or 12.52 (95%CI=7.31-22.47), respectively. Therefore, the FASL-844T>C polymorphism is associated with genetic susceptibility of developing laryngeal and hypopharyngeal SCC in a Han Chinese population.

Genetic polymorphisms in the Fas and FasL genes are associated with epithelial ovarian cancer risk and clinical outcomes

AIM

In this study, we evaluated whether functional polymorphisms within the Fas and FasL genes were associated with the risk of developing epithelial ovarian cancer (EOC) and survival of patients with EOC.

METHODS

A case-control study was performed in 342 EOC patients and 344 control women. The genotypes of three promoter region polymorphisms (Fas -1377G/A, -670A/G and FasL -844T/C) were determined using ligase detection reaction-polymerase chain reaction (LDR-PCR). The clinical outcomes in 202 EOC patients were compared across genotypes.

RESULTS

The genotype frequencies of the FasL -844 T/C polymorphism were significantly different between the case and control groups (P=0.034). Compared to the T/T and T/C genotypes, the C/C genotype significantly increased the risk of developing EOC (OR=1.46, 95% CI=1.08-1.99). The survival analysis showed that the Fas -1377G/A and -670A/G polymorphisms were related to prognosis in EOC patients. Compared with patients with the G/G genotype of the -1377G/A polymorphism, patients carrying the A allele had a shorter PFS and OS, as determined by univariate and multivariate analysis (HR=1.81, 95% CI=1.26-2.62 and HR=1.86, 95% CI=1.15-3.00, respectively). Similarly, Kaplan-Meier and Cox proportional hazard model analyses indicated that patients carrying the G allele of Fas -670A/G polymorphisms had shorter PFS and OS than those carrying the AA genotype (HR=1.67, 95% CI=1.15-2.42 and HR=1.80, 95% CI=1.10-2.94, respectively).

CONCLUSIONS

Functional polymorphisms in the Fas and FasL genes may be involved in epithelial ovarian cancer development and progression in northern Chinese women.

Human FasL gene is a target of β-catenin/T-cell factor pathway and complex FasL haplotypes alter promoter functions

FasL expression on human immune cells and cancer cells plays important roles in immune homeostasis and in cancer development. Our previous study suggests that polymorphisms in the FasL promoter can significantly affect the gene expression in human cells. In addition to the functional FasL SNP -844C>T (rs763110), three other SNPs (SNP -756A>G or rs2021837, SNP -478A>T or rs41309790, and SNP -205 C>G or rs74124371) exist in the proximal FasL promoter. In the current study, we established three major FasL hyplotypes in humans. Interestingly, a transcription motif search revealed that the FasL promoter possessed two consensus T-cell factor (TCF/LEF1) binding elements (TBEs), which is either polymorphic (SNP -205C>G) or close to the functional SNP -844C>T. Subsequently, we demonstrate that both FasL TBEs formed complexes with the TCF-4 and β-catenin transcription factors in vitro and in vivo. Co-transfection of LEF-1 and β-catenin transcription factors significantly increased FasL promoter activities, suggesting that FasL is a target gene of the β-catenin/T-cell factor pathway. More importantly, we found that the rare allele (-205G) of the polymorphic FasL TBE (SNP -205C>G) failed to bind the TCF-4 transcription factor and that SNP -205 C>G significantly affected the promoter activity. Furthermore, promoter reporter assays revealed that FasL SNP haplotypes influenced promoter activities in human colon cancer cells and in human T cells. Finally, β-catenin knockdown significantly decreased the FasL expression in human SW480 colon cancer cells. Collectively, our data suggest that β-catenin may be involved in FasL gene regulation and that FasL expression is influenced by FasL SNP haplotypes, which may have significant implications in immune response and tumorigenesis.

Interleukin-13 induces T helper type 2 immune responses in OVA-immunized BALB/c mice bearing a T cell lymphoma

T lymphocytes play a crucial role in the regulation of immune responses against the tumour cells. Tumour progression results in dysfunction and inhibition of T cells, which ultimately leads to impairment in the antitumour immune response. The impaired antitumour immune response in the host is represented by the decreased number of T cells and their incomplete and improper function. The immunosuppressive network in tumour-bearing host mediated by tumour cells also leads to the inequities of T cell subsets and imbalance of Th1/Th2 dichotomy. Therefore, in the present study, we sought to investigate the role of tumour progression in the development of T cell phenotype and the involvement of interleukin-13 thereof selecting Dalton's lymphoma (DL) as a tumour model. It was observed that a significant increase in the number of CD4(+) T cell population, whereas a significant decline in the CD8(+) T cells among lymphoid cell population of OVA-immunized DL-bearing BALB/c mice occurs. Similar observation was found following the administration of IL-13 to the normal healthy mice. It was further confirmed that expansion in Th2 type cells among CD4(+) T cell population occurs following the progression of tumour and administration of IL-13 to normal healthy mice by an yet to define mechanism. Therefore, it can be concluded that IL-13 has immense role in polarizing the immune responses by inducing the differentiation of Th2 type of cells.

Vitamin E and immunity

Vitamin E is the most important chain-breaking, lipid-soluble antioxidant present in body tissues of all cells and is considered the first line of defense against lipid peroxidation and it is important for normal function of the immune cells. However, vitamin E deficiency is rare in well-nourished healthy subjects and is not a problem, even among people living on relatively poor diets, both T- and B-cell functions are impaired by vitamin E deficiency. While immune cells are particularly enriched in vitamin E because of their high polyunsaturated fatty acid content, this point puts them at especially high risk for oxidative damage. Besides its immunomodulatory effects, vitamin E also plays an important role in carcinogenesis with its antioxidant properties against cancer, and ischemic heart disease with limiting the progression of atherosclerosis. Supplementation of vitamin E significantly enhances both cell mediated and humoral immune functions in humans, especially in the elderly and animals.

Covalent linking of proteins and cytokines to suture: Enhancing the immune response of head and neck cancer patients

BACKGROUND

The immune system of advanced stage head and neck cancer patients is frequently suppressed. Poor immune function has been correlated with poor clinical outcome. Immunotherapeutic strategies have been previously attempted in an effort to enhance immune function and improve survival. Previous studies have shown surgical suture can be transformed into an immune stimulant capable of activating the T lymphocytes of cancer patients. The development of a process for covalently linking proteins and cytokines to suture could have enormous potential for the in vivo manipulation of the immune system.

HYPOTHESIS

We hypothesize proteins and cytokines can be covalently linked to surgical suture while preserving their functional properties.

STUDY DESIGN

Prospective study testing normal donor and head and neck squamous cell carcinoma (HNSCC) patient lymphocytes.

METHOD

Polyester suture was acid hydrolyzed followed by reacting with 1-ethyl-3(-3-dimethylamino propyl carbodiimide) (EDAC) to create a suture-EDAC intermediate. Next, selected proteins (horseradish peroxidase [HRP] or bovine serum albumin [BSA]) or cytokines (interleukin [IL]-2 or interferon [IFN]-gamma) were reacted with the suture-EDAC intermediate to test the covalent linkage of the selected protein or cytokine to suture. Functional activity of the linked proteins was measured spectrophotometrically. The linking of cytokines to suture was tested by stimulating normal donor peripheral blood lymphocytes (PBL) or HNSCC patients' lymphocytes. The functional activity was confirmed by proliferation, enzyme linked immunoadsorbent assay (ELISA), and phenotype expression of T cells. RESULTS The conditions for optimally linking a protein to polyester suture were defined using HRP as a model protein. HRP retained its enzymatic activity. The optimal conditions for linking IL-2 or IFN-gamma were defined. The covalently linked cytokines retained their immune enhancing properties for stimulating PBL and lymph node lymphocytes (LNL) from HNSCC patients to proliferate, generate a TH1 immunologic profile of cytokines (IL-2, IL-12, IFN-gamma), and stimulate T lymphocytes.

CONCLUSION

This is the first report to demonstrate that cytokines can be covalently linked to surgical sutures and retain their immune-stimulating properties. Proteins linked to suture also retained their enzymatic activity. The clinical implications of functionally active cytokines or proteins linked to surgical suture may be very significant in the future for manipulating the immune system in vivo or enhancing wound healing.

Functional polymorphisms in cell death pathway genes and risk of renal cell carcinoma

The FAS/FAS ligand (FASL) system plays a key role in regulating apoptotic cell death, and corruption of this signaling pathway has been shown to participate in tumorigenesis. However, the effects of functional promoter polymorphisms of the CASP8, FAS, and FASL genes on risk of renal cell carcinoma (RCC) are unknown. In this study, we genotyped CASP8 -652 6N ins/del, FAS -1377 G > A, FAS -670 A > G, and FASL -844 C > T polymorphisms in a hospital-based case-control study of 353 patients diagnosed with RCC and 365 cancer-free controls in a Chinese population. Compared with CASP8 -652 ins/ins genotype, the del/del genotype had a significantly decreased RCC risk [adjusted odds ratio (OR) = 0.36, 95% confidence interval (CI) = 0.16-0.84]. For FAS -1377 G > A polymorphism, a significantly increased risk of RCC was found for AA (adjusted OR = 1.65, 95% CI = 1.03-2.64) and GA (adjusted OR = 1.41, 95% CI = 1.02-1.94) genotypes compared with GG genotype. When we combined these two polymorphisms together, we found that individuals carrying CASP8 -652 6N ins/del and FAS -1377 GG genotypes or CASP8 -652 6N del/del and FAS -1377 GG genotypes were associated with a statistically significantly decreased risk of RCC (adjusted OR = 0.46, 95% CI = 0.24-0.88 and OR = 0.12, 95% CI = 0.02-0.58, respectively) compared with individuals carrying CASP8 -652 6N ins/ins and FAS -1377 AA genotypes. These results suggest that the CASP8 -652 6N ins/del and FAS -1377 G > A polymorphisms are involved in the susceptibility to developing RCC in Chinese populations.

CD95 promotes tumour growth

CD95 (also called Fas and APO-1) is a prototypical death receptor that regulates tissue homeostasis mainly in the immune system through induction of apoptosis 1-3. During cancer progression CD95 is frequently downregulated or cells are rendered apoptosis resistant 4,5 raising the possibility that loss of CD95 is part of a mechanism for tumour evasion. However, complete loss of CD95 is rarely seen in human cancers 4 and many cancer cells express large quantities of CD95 and are highly sensitive to CD95 mediated apoptosis in vitro. Furthermore, cancer patients frequently have elevated levels of the physiological ligand for CD95, CD95L 6. These data raise the intriguing possibility that CD95 could actually promote the growth of tumours through its nonapoptotic activities 7. Here we show that cancer cells in general, regardless of their CD95 apoptosis sensitivity, depend on constitutive activity of CD95, stimulated by cancer-produced CD95L, for optimal growth. Consistently, loss of CD95 in mouse models of ovarian cancer and liver cancer reduces cancer incidence as well as the size of the tumours. The tumorigenic activity of CD95 is mediated by a pathway involving JNK and c-Jun. These results demonstrate that CD95 plays a growth promoting role during tumorigenesis and suggest that efforts to inhibit its activity rather than to enhance its activation should be considered during cancer therapy.

Whole tumor antigen vaccines

Although cancer vaccines with defined antigens are commonly used, the use of whole tumor cell preparations in tumor immunotherapy is a very promising approach and can obviate some important limitations in vaccine development. Whole tumor cells are a good source of TAAs and can induce simultaneous CTLs and CD4(+) T helper cell activation. We review current approaches to prepare whole tumor cell vaccines, including traditional methods of freeze-thaw lysates, tumor cells treated with ultraviolet irradiation, and RNA electroporation, along with more recent methods to increase tumor cell immunogenicity with HOCl oxidation or infection with replication-incompetent herpes simplex virus.

Polymorphisms in promoter region of FAS and FASL gene and risk of cardia gastric adenocarcinoma

BACKGROUND AND AIM

The FAS and FASL system play an important role in regulating apoptotic cell death. This study was designed to investigate the correlation of FAS-1377 G/A, -670 A/G and FASL-844 T/C polymorphisms with susceptibility to gastric cardiac adenocarcinoma in a population of a high-incidence region of Hebei Province.

METHODS

FAS-1377 G/A, -670 A/G and FASL-844 T/C polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis in 262 gastric cardiac carcinoma (GCA) patients and 524 healthy controls.

RESULTS

Family history of upper gastrointestinal cancer (UGIC) might increase the risk of developing GCA (age- and sex-adjusted odds ratio [OR] = 1.38, 95% confidence interval [CI] = 1.02-1.86). The overall allelotype and genotype distributions of FAS-1377 G/A, and FASL-844 T/C polymorphisms in GCA patients did not significantly differ from that in healthy controls (P > 0.05). Compared with individuals with a FAS-670 A/A genotype, individuals with an A/G genotype in a smoker group had a lower risk of developing GCA (age, sex, and family history of UGIC adjusted OR = 0.55, 95% CI = 0.34-0.88). When the genotypes of FAS and FASL single nucleotide polymorphisms (SNP) were combined to analyze, no significant correlation was found between these SNP and the risk for GCA development.

CONCLUSION

In the high-incidence region of Hebei Province, FAS-1377 G/A and FASL-844 T/C polymorphisms were not associated with the risk of GCA. However, the FAS-670 A/G genotype might decrease the risk of GCA for smoker individuals.

T cell density and location can influence the prognosis of ovarian cancer

The aims of this study were to examine the significance of CD3+ cells in patients with epithelial ovarian cancer and to determine their influence on the disease in relation to their location within tumours. A 157-core tissue-microarray constructed from primary ovarian cancer patients treated at Nottingham-University-Hospitals (2000-2007) was stained for the T-cell marker CD3. The number of CD3+ cells in direct contact with tumour cells was counted per tumour area. These were considered as "intra-tumoural T-cells (ITTC)". Cores were divided into CD3 'high' or 'low' density tumours. "Stromal T-cells (STC)" were assigned as 'positive' or 'negative'. The study population had a median follow-up time of 36-months (0-75). The number of ITTC counted in tumour cores ranged between 0 and 184/mm(2). 90-tumours-(57%) were found to be in the "low-density" rubric, while 56-(36%) were of a "high-density" T-cell population. STC were found in 118-cores-(75%)-compared to 22-cores-(14%)-negative cores. Higher number of ITTC correlated with lower-grade-(p = 0.045), tumour-type-(p = 0.034), and longer-median-survival-times (57-versus 37-months for high-and low-ITTC densities, respectively, p = 0.038). This relationship was reversed when tumours were infiltrated by CD3+ cells in the stroma, predicting worse-survival (Log-rank-test, p = 0.028). Combining ITTC with STC produced an interesting pattern where the ITTC-low/STC + ve had the worst prognosis (p = 0.003). Infiltration of ovarian cancer by T-cells can influence its prognosis depending on the location of these cells (intra-tumoural-versus-stromal). The former predicts improved survival, while the latter is probably contributing to tumour progression and, in turn, worse survival.

Tumor-shed PGE(2) impairs IL2Rgammac-signaling to inhibit CD4 T cell survival: regulation by theaflavins

Background

Many tumors are associated with decreased cellular immunity and elevated levels of prostaglandin E2 (PGE2), a known inhibitor of CD4+ T cell activation and inducer of type-2 cytokine bias. However, the role of this immunomodulator in the survival of T helper cells remained unclear. Since CD4+ T cells play critical roles in cell-mediated immunity, detail knowledge of the effect tumor-derived PGE2 might have on CD4+ T cell survival and the underlying mechanism may, therefore, help to overcome the overall immune deviation in cancer.

Methodology/Principal Findings

By culturing purified human peripheral CD4+ T cells or Jurkat cells with spent media of theaflavin- or celecoxib-pre-treated MCF-7 cells, we show that tumor-shed PGE2 severely impairs interleukin 2 receptor γc (IL2Rγc)-mediated survival signaling in CD4+ T cells. Indeed, tumor-shed PGE2 down-regulates IL2Rγc expression, reduces phosphorylation as well as activation of Janus kinase 3 (Jak-3)/signal transducer and activator of transcription 5 (Stat-5) and decreases Bcl-2/Bax ratio thereby leading to activation of intrinsic apoptotic pathway. Constitutively active Stat-5A (Stat-5A1*6) over-expression efficiently elevates Bcl-2 levels in CD4+ T cells and protects them from tumor-induced death while dominant-negative Stat-5A over-expression fails to do so, indicating the importance of Stat-5A-signaling in CD4+ T cell survival. Further support towards the involvement of PGE2 comes from the results that (a) purified synthetic PGE2 induces CD4+ T cell apoptosis, and (b) when knocked out by small interfering RNA, cyclooxygenase-2 (Cox-2)-defective tumor cells fail to initiate death. Interestingly, the entire phenomena could be reverted back by theaflavins that restore cytokine-dependent IL2Rγc/Jak-3/Stat-5A signaling in CD4+ T cells thereby protecting them from tumor-shed PGE2-induced apoptosis.

Conclusions/Significance

These data strongly suggest that tumor-shed PGE2 is an important factor leading to CD4+ T cell apoptosis during cancer and raise the possibility that theaflavins may have the potential as an effective immunorestorer in cancer-bearer.

Spontaneous apoptosis of tumor-specific tetramer+ CD8+ T lymphocytes in the peripheral circulation of patients with head and neck cancer

BACKGROUND

In cancer, tumor escape from the host immune system includes apoptosis of circulating CD3(+)CD8(+) effector T lymphocytes. Here, we compare sensitivity to apoptosis of virus- with tumor-specific circulating CD8(+) T cells in patients with head and neck cancer.

METHODS

Wild-type p53 peptide-specific (p53(264-272) and p53(149-157)) and viral peptide-specific (EBV BMLF(259-267) and CMVpp65(495-503)) tetramers were used to measure the frequency of reactive T cells by flow cytometry. Annexin V (ANX) binding to circulating 7-amino-actinomycin D-negative but tetramer(+)CD8(+) T cells in PBMC obtained from 21 patients with head and neck cancer and 11 normal controls (NC) was evaluated.

RESULTS

In patients with head and neck cancer, a higher percentage of tetramer(+)CD8(+) than tetramer(-)CD8(+) T cells bound ANX (p < .023-.005). Although most tumor-epitope(+)CD8(+) T cells bound ANX, lower percentages of virus-specific CD8(+) T cells were ANX(+) in the same patients.

CONCLUSIONS

Preferential demise of circulating tumor-specific CD8(+) T cells and their paucity in head and neck cancer contribute to tumor escape.

The role of immunity in elderly cancer

The increased incidence of malignancies in elderly patients living in industrialized countries has led to both identify the causes that alter the normal homeostatic balance in elderly and designate the specific treatments. The progressive decline of the immune system (immunosenescence) involving cellular and molecular alterations impact both innate and adaptive immunity. The immunosenescence leads to increased incidence of infectious diseases morbidity and mortality as well as heightened rates of other immune disorders such as autoimmunity, cancer, and inflammatory conditions. Here, we summarize the knowledge on the major changes in the immune system associated with aging in primary lymphoid organs as well as a description of molecular mechanisms, and the impact on cancer development.

Tricks tumors use to escape from immune control

Tumor escape from the host immune system has been a major problem in immunotherapy of human malignancies. Human tumors are known to develop escape strategies, which might differ among tumors of the same histology. This suggests that host-tumor interactions create the tumor microenvironment that is unique for every tumor. Recent advances in cancer immunology allow for a better understanding of the mechanisms tumors use to execute immune escape and of the relationship the tumor establishes with immune cells. It is now feasible to obtain an "immune signature" of the tumor, that is to define the genetic, molecular and functional profiles of immune cells in the tumor microenvironment. This knowledge might be critically important for the personalized selection of available therapies and thus for clinical outcome.

Increase in tumour-infiltrating lymphocytes with regulatory T cell immunophenotypes and reduced zeta-chain expression in nasopharyngeal carcinoma patients

The pathological significance of the mechanisms of tumour immune-evasion and/or immunosuppression, such as loss of T cell signalling and increase in regulatory T cells (T(regs)), has not been well established in the nasopharyngeal carcinoma (NPC) microenvironment. To evaluate the T(reg) immunophenotypes in tumour-infiltrating lymphocytes (TILs), we performed a double-enzymatic immunostaining for detection of forkhead box P3 (FoxP3) and other markers including CD4, CD8, and CD25 on 64 NPC and 36 non-malignant nasopharyngeal (NP) paraffin-embedded tissues. Expression of CD3 zeta and CD3 epsilon was also determined. The prevalence of CD4(+)FoxP3(+) cells in CD4(+) T cells and the ratio of FoxP3(+)/CD8(+) were increased significantly in NPC compared with those in NP tissues (P < 0.001 and P = 0.025 respectively). Moreover, the ratio of FoxP3(+)/CD25(+)FoxP3(-) in NPC was significantly lower than that in NP tissues (P = 0.005), suggesting an imbalance favouring activated phenotype of T cells in NPC. A significant negative correlation between the abundance of FoxP3(+) and CD25(+)FoxP3(-) cells (P < 0.001) was also identified. When histological types of NPC were considered, a lower ratio of FoxP3(+)/CD25(+)FoxP3(-) was found in non-keratinizing and undifferentiated carcinomas. Increased CD4(+)FoxP3(+)/CD4(+) proportion and FoxP3(+)/CD8(+) ratio were associated with keratinizing squamous cell carcinoma. A reduced expression of CD3 zeta in TILs was found in 20.6% of the NPC tissues but none of the NP tissues. These data provide evidence for the imbalances of T(reg) and effector T cell phenotypes and down-regulation of signal-transducing molecules in TILs, supporting their role in suppression of immune response and immune evasion of NPC.

Arginine regulation by myeloid derived suppressor cells and tolerance in cancer: mechanisms and therapeutic perspectives

Patients with cancer have an impaired T-cell response that can decrease the potential therapeutic benefit of cancer vaccines and other forms of immunotherapy. L-arginine (L-Arg) is a conditionally essential amino acid that is fundamental for the function of T lymphocytes. Recent findings in tumor-bearing mice and cancer patients indicate that increased metabolism of L-Arg by myeloid derived suppressor cells (MDSCs) producing arginase I inhibits T-lymphocyte responses. Here we discuss some of the most recent concepts how MDSC expressing arginase I may regulate T-cell function in cancer and other chronic inflammatory diseases and suggest possible therapeutic interventions to overcome this inhibitory effect.

The impact of T-cell immunity on ovarian cancer outcomes

Ovarian cancer remains a challenging disease for which improved treatments are urgently needed. Most patients present with advanced disease that is highly responsive to surgery combined with platinum- and taxane-based chemotherapy, with a state of minimal residual disease being achieved in many cases. However, chemotherapy-resistant recurrent tumors typically appear within 1-5 years and are ultimately fatal. Recently, several groups have shown that ovarian tumors are often infiltrated by activated T cells at the time of diagnosis, and patients with dense infiltrates of CD3+CD8+ T cells experience unexpectedly favorable progression-free and overall survival. Other cell types in the immune infiltrate oppose anti-tumor immunity, including CD4+CD25+FoxP3+ regulatory T cells, CD8+ regulatory T cells, macrophages, and dendritic cells. The composition of immune infiltrates is shaped by the expression of cytokines, chemokines, antigens, major histocompatibility complex molecules, and costimulatory molecules. The relationship between these various immunological factors is reviewed here with a strong emphasis on outcomes data so as to create a knowledge base that is well grounded in clinical reality. With improved understanding of the functional properties of natural CD8+ T-cell responses to ovarian cancer, there is great potential to improve clinical outcomes by amplifying host immunity.

Renal cell carcinoma tumors induce T cell apoptosis through receptor-dependent and receptor-independent pathways

Tumors can promote their own progressive growth by inducing T cell apoptosis. Though previous studies suggested that tumor-mediated T cell killing is receptor dependent, we recently showed that tumor gangliosides also participate, a notion consistent with reports indicating that, in some cell types, gangliosides can activate the intrinsic apoptotic pathway by stimulating reactive oxygen species production, cytochrome c release, and caspase-9 activation. In this study, we used normal peripheral blood T cells, as well as caspase-8-, caspase-9-, and Fas-associated death domain protein-deficient Jurkat cells, to assess whether the death ligands and gangliosides overexpressed by the renal cell carcinoma (RCC) cell line SK-RC-45 can independently stimulate T cell apoptosis as a mechanism of immune escape. Anti-FasL Abs and the glycosylceramide synthase inhibitor 1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol (PPPP) each partially inhibited the ability of SK-RC-45 to kill cocultured activated T cells; together, as purified molecules, RCC gangliosides and rFasL induced a more extensive mitochondrial permeability transition and greater levels of apoptosis than either agent alone, equivalent to that induced by the FasL- and ganglioside-expressing RCC line itself. rFasL-mediated apoptosis was completely inhibited in caspase-8- and Fas-associated death domain protein-negative Jurkat cells, though apoptosis induced by purified gangliosides remained intact, findings that correlate with the observed partial inhibition of SK-RC-45-induced apoptosis in the Jurkat lines with defective death receptor signaling. Western blot analysis performed on lysates made from wild-type and mutant Jurkat cells cocultured with SK-RC-45 revealed caspase activation patterns and other biochemical correlates which additionally supported the concept that tumor-associated gangliosides and FasL independently activate the caspase cascade in T cells through the intrinsic and extrinsic pathways, respectively.

Functional Variants in Cell Death Pathway Genes and Risk of Pancreatic Cancer

Purpose: Fas-Fas ligand (FasL)–mediated death pathway is important in the life and death of immune cells and, therefore, influences immune surveillance of carcinogenesis. This study examined the association between functional variants of Fas (−1377G→A and −670A→G), FasL (−844T→C), and caspase-8 (CASP8) six-nucleotide deletion polymorphism (−652 6N ins→del) and risk of pancreatic cancer.

Experimental Design: Genotypes were determined in 397 cases with pancreatic cancer and 907 controls. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by logistic regression, and all statistical tests were two sided.

Results: We found a significant decrease in risk of pancreatic cancer associated with FasL and CASP8 but not Fas polymorphisms. Compared with noncarriers, the ORs of developing pancreatic cancer for FasL −844CT and TT carriers were 0.73 (95% CI, 0.57-0.94) and 0.35 (95% CI, 0.19-0.63), and for CASP8 −652 6N ins/del and del/del carriers were 0.65 (95% CI, 0.50-0.85) and 0.56 (95% CI, 0.33-0.98), respectively. Gene-gene interaction between the FasL and CASP8 variants further reduced the cancer risk in a multiplicative manner (OR for the presence of both FasL −844TT and CASP8 −652 6N del/del genotype, 0.10; 95% CI, 0.01-0.75). On the other hand, a multiplicative joint effect between the FasL −844CC or CASP8 −652 6N ins/ins genotype and smoking or diabetes mellitus in intensifying risk of pancreatic cancer was also evident.

Conclusions: These results suggest that genetic variations in the death pathway genes FasL and CASP8 are involved in susceptibility to developing pancreatic cancer.

Tumor-induced senescent T cells with suppressor function: a potential form of tumor immune evasion

Senescent and suppressor T cells are reported to be increased in select patients with cancer and are poor prognostic indicators. Based on the association of these T cells and poor outcomes, we hypothesized that tumors induce senescence in T cells, which negatively effects antitumor immunity. In this report, we show that human T cells from healthy donors incubated with tumor for only 6 h at a low tumor to T-cell ratio undergo a senescence-like phenotype, characterized by the loss of CD27 and CD28 expression and telomere shortening. Tumor-induced senescence of T cells is induced by soluble factors and triggers increases in expression of senescence-associated molecules such as p53, p21, and p16. Importantly, these T cells are not only phenotypically altered, but also functionally altered as they can suppress the proliferation of responder T cells. This suppression requires cell-to-cell contact and is mediated by senescent CD4(+) and CD8(+) subpopulations, which are distinct from classically described natural T regulatory cells. Our observations support the novel concept that tumor can induce senescent T cells with suppressor function and may effect both the diagnosis and treatment of cancer.

Phosphatidylinositol 3-Kinase/Akt Activation by Integrin-Tumor Matrix Interaction Suppresses Fas-Mediated Apoptosis in T Cells

It has recently become apparent that the microenvironment made up of the extracellular matrix may affect cell signaling. In this study, we evaluated Fas-triggered apoptosis in T cells in contact with tumor cells, which resembles the cell-to-cell interactions found in tumor regions. Jurkat cells were less susceptible to the Fas-mediated apoptosis when cocultured with U118, HeLa, A549, and Huh-7 tumor cells. This was indicated by less plasma membrane alteration, an amelioration of the loss of mitochondria membrane potential, a decrease in caspase-8 and caspase-3 activation, a decrease in DNA fragmentation factor-45/35 cleavage, and a reduction in the breakage of DNA when compared with Jurkat cells cultured alone. In contrast, the tumor cell lines MCF-7 and HepG2 produced no such protective effect. This protective event was independent of the expression of Fas ligand on the tumor cells. Interrupting the beta integrins-matrix interaction diminished the coculture effect. In Jurkat cells, cell matrix contact reduced the assembly of the Fas death-inducing signaling complex and Bcl-x(L) cleavage, but enhanced the phosphorylation of ERK1/2, p38 MAPK, and Akt. Only PI3K inhibitor, but not kinase inhibitors for MEK, ERK1/2, p38 MAPK, JNK, protein kinase C, and protein kinase A, completely abolished this tumor cell contact-associated protection and in parallel restored Fas-induced Bcl-x(L) cleavage as well as decreasing the phosphorylation of Bad at serine 136. Together, our results indicate that stimulation of the beta integrin signal of T cells by contact with tumor cells may trigger a novel protective signaling through the PI3K/Akt pathway of T cells against Fas-mediated apoptosis.

Intratumoral CRH modulates immuno-escape of ovarian cancer cells through FasL regulation

Although corticotropin-releasing hormone (CRH) and Fas ligand (FasL) have been documented in ovarian carcinoma, a clear association with tumour progression and immuno-escape has not been established. FasL plays an important role in promoting tumour cells' ability to counterattack immune cells. Here, we examined immunohistochemically the expression of CRH, CRHR1, CRHR2 and FasL in 47 human ovarian cancer cases. The ovarian cancer cell lines OvCa3 and A2780 were further used to test the hypothesis that CRH might contribute to the immune privilege of ovarian tumours, by modulating FasL expression on the cancer cells. We found that CRH, CRHR1, CRHR2 and FasL were expressed in 68.1, 70.2, 63.8 and 63.8% of the cases respectively. Positivity for CRH or FasL expression was associated with higher tumour stage. Finally, CRH increased the expression of FasL in OvCa3 and A2780 cells through CRHR1 thereby potentiated their ability to induce apoptosis of activated peripheral blood lymphocytes. Corticotropin-releasing hormone produced by human ovarian cancer might favour survival and progression of the tumour by promoting its immune privilege. These findings support the hypothesis that CRHR1 antagonists could potentially be used against ovarian cancer.

A short-term dietary supplementation with high doses of vitamin E increases NK cell cytolytic activity in advanced colorectal cancer patients

Cancer patients with advanced disease display signs of immune suppression, which constitute a major obstacle for effective immunotherapy. Both T cells and NK cells are affected by a multitude of mechanisms of which the generation of reactive oxygen species is of major importance. Therefore, we hypothesized that two weeks of high-dose treatment with the anti-oxidant vitamin E may enhance NK cell function in cancer patients by protecting from oxidative stress. Seven patients with colorectal cancer (Dukes stage C and D) received a daily dose of 750 mg of vitamin E during a period of two weeks and the function, phenotype and receptor expression of NK cells were analyzed. The short-term vitamin E treatment significantly improved NK cell cytolytic activity in six out of the seven patients analyzed. The increased NK cell activity in patients' PBMC was not due to increased numbers of NK cells or an increase in the proportion of the CD56(dim) NK cell subpopulation. Furthermore, neither an increased perforin expression nor an enhanced ability of NK cells to produce IFN-gamma was observed as a result of vitamin E treatment. Finally, vitamin E treatment was associated with a minor, but consistent, induction of NKG2D expression in all patients analyzed. In conclusion, this pilot study demonstrates that vitamin E may boost NK cell function in patients with colorectal cancer. Further studies are warranted to explore the potential of vitamin E as an adjuvant for immunotherapy against cancer and to determine the underlying mechanism(s) behind vitamin E induced NK cell activation.

Arginase, prostaglandins, and myeloid-derived suppressor cells in renal cell carcinoma

Tumor-induced tolerance is a well-established phenomenon in cancer patients that can severely impair the therapeutic efficacy of immunotherapy. One mechanism leading to T-cell tolerance is the generation of myeloid-derived suppressor cells (MDSC) by soluble factors produced by the tumor. MDSC express CD11b(+) as a common marker but may vary in their stage of maturation, depending on the tumor factors being produced. Arginase production by MDSC depletes arginine from the tumor microenvironment and impairs T-cell signal transduction and function. We studied whether an increase in MDSC could explain the molecular alterations and dysfunction found in T cells of patients with renal cell carcinoma (RCC). Arginase activity in the peripheral blood mononuclear cells of 117 RCC patients was increased between 6- to 8-fold compared with normal controls. The increased arginase activity was limited to the CD11b(+)CD14(-) myeloid cells and resulted in significantly decreased serum levels of arginine and increased ornithine in patients. Depletion of MDSC restored IFN-gamma production and T-cell proliferation. Preliminary data suggest that prostaglandin E(2) produced by the tumor induces arginase I expression in MDSC. Therefore, blocking MDSC activity may enhance the therapeutic efficacy of immunotherapy in RCC.

Curcumin prevents tumor-induced T cell apoptosis through Stat-5a-mediated Bcl-2 induction

Patients with advanced cancer exhibit multifaceted defects in their immune capacity, which are likely to contribute to an increased susceptibility to infections and disease progression. We demonstrated earlier that curcumin inhibits tumor growth and prevents immune cell death in tumor-bearing hosts. Here we report that tumor-induced immunodepletion involves apoptosis of thymic CD4+/CD8+ single/double positive cells as well as loss of circulating CD4+/CD8+ T cells. Administration of curcumin to tumor-bearing animals resulted in restoration of progenitor, effecter, and circulating T cells. In fact, tumor burden decreased the expression level of the pro-proliferative protein Bcl-2 while increasing the pro-apoptotic protein Bax in T cells. Curcumin down-regulated the Bax level while augmenting Bcl-2 expression in these cells, thereby protecting the immunocytes from tumor-induced apoptosis. A search for the upstream mechanism revealed down-regulation of the common cytokine receptor gamma chain (gammac) expression in T cells by tumor-secreted prostaglandin E2. As a result, Jak-3 and Stat-5a phosphorylation and to a lesser extent Stat-5b phosphorylation were also decreased in T cells. These entire phenomena could be reverted back by curcumin, indicating that this phytochemical restored the cytokine-dependent Jak-3/Stat-5a signaling pathway in T cells of tumor bearers. Overexpressed Stat-5a/constitutively active Stat-5a1*6 but not Stat-5b could efficiently elevate Bcl-2 levels and protect T cells from tumor-induced death, whereas C-terminal truncated Stat-5a713 overexpression failed to do so, indicating the importance of Stat-5a signaling in T cell survival. Thus, these results raise the possibility of inclusion of curcumin in successful therapeutic regimens against cancer.

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.