Expression of high levels of human proteinase inhibitor 9 blocks both perforin/granzyme and Fas/Fas ligand-mediated cytotoxicity

Signaling by Type I Interferons in Immune Cells: Disease Consequences

This review addresses interferon (IFN) signaling in immune cells and the tumor microenvironment (TME) and examines how this affects cancer progression. The data reveal that IFNs exert dual roles in cancers, dependent on the TME, exhibiting both anti-tumor activity and promoting cancer progression. We discuss the abnormal IFN signaling induced by cancerous cells that alters immune responses to permit their survival and proliferation.

Decoding the mechanisms of chimeric antigen receptor (CAR) T cell-mediated killing of tumors: insights from granzyme and Fas inhibition

Chimeric antigen receptor (CAR) T cell show promise in cancer treatments, but their mechanism of action is not well understood. Decoding the mechanisms used by individual T cells can help improve the efficacy of T cells while also identifying mechanisms of T cell failure leading to tumor escape. Here, we used a suite of assays including dynamic single-cell imaging of cell-cell interactions, dynamic imaging of fluorescent reporters to directly track cytotoxin activity in tumor cells, and scRNA-seq on patient infusion products to investigate the cytotoxic mechanisms used by individual CAR T cells in killing tumor cells. We show that surprisingly, overexpression of the Granzyme B (GZMB) inhibitor, protease inhibitor-9 (PI9), does not alter the cytotoxicity mediated by CD19-specific CAR T cells against either the leukemic cell line, NALM6; or the ovarian cancer cell line, SkOV3-CD19. We designed and validated reporters to directly assay T cell delivered GZMB activity in tumor cells and confirmed that while PI9 overexpression inhibits GZMB activity at the molecular level, this is not sufficient to impact the kinetics or magnitude of killing mediated by the CAR T cells. Altering cytotoxicity mediated by CAR T cells required combined inhibition of multiple pathways that are tumor cell specific: (a) B-cell lines like NALM6, Raji and Daudi were sensitive to combined GZMB and granzyme A (GZMA) inhibition; whereas (b) solid tumor targets like SkOV3-CD19 and A375-CD19 (melanoma) were sensitive to combined GZMB and Fas ligand inhibition. We realized the translational relevance of these findings by examining the scRNA-seq profiles of Tisa-cel and Axi-cel infusion products and show a significant correlation between GZMB and GZMA expression at the single-cell level in a T cell subset-dependent manner. Our findings highlight the importance of the redundancy in killing mechanisms of CAR T cells and how this redundancy is important for efficacious T cells.

A peptides-based biosensor with target-triggered charge-switchable property for simple and sensitive detection of Granzyme B

Granzyme B (GrB) is a serine protease released by natural killer cells and cytotoxic T lymphocytes during immune responses, which not only plays a role in tumor diagnosis but also provides valuable guidance during tumor treatment. In this work, we have designed a charge-switching peptide to fabricate an electrochemical biosensor for quantitative analysis of GrB. Specifically, the designed zwitterionic peptide is in an electrically neutral state before activation, and a door lock structure (proline) is constructed by utilizing the selectivity of carboxypeptidase A (CPA) to the carboxy-terminus of the peptide chain. The door lock is opened when the target is present, allowing CPA to hydrolyze the peptide. At this time, the peptide will convert from neutral to positive, triggering the assembly of a positively charged peptide layer on the electrode surface, resulting in a signal change. Studies have shown that the biosensor has good analytical performance, with a detection range of 0.01 pM-8 pM and a detection limit as low as 3.5 fM. Moreover, the developed biosensor has been effectively applied to the analysis of clinical samples, demonstrating its ability to monitor tumor progression and treatment with clinical applications.

Exploiting RIG-I-like receptor pathway for cancer immunotherapy

RIG-I-like receptors (RLRs) are intracellular pattern recognition receptors that detect viral or bacterial infection and induce host innate immune responses. The RLRs family comprises retinoic acid-inducible gene 1 (RIG-I), melanoma differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2) that have distinctive features. These receptors not only recognize RNA intermediates from viruses and bacteria, but also interact with endogenous RNA such as the mislocalized mitochondrial RNA, the aberrantly reactivated repetitive or transposable elements in the human genome. Evasion of RLRs-mediated immune response may lead to sustained infection, defective host immunity and carcinogenesis. Therapeutic targeting RLRs may not only provoke anti-infection effects, but also induce anticancer immunity or sensitize "immune-cold" tumors to immune checkpoint blockade. In this review, we summarize the current knowledge of RLRs signaling and discuss the rationale for therapeutic targeting RLRs in cancer. We describe how RLRs can be activated by synthetic RNA, oncolytic viruses, viral mimicry and radio-chemotherapy, and how the RNA agonists of RLRs can be systemically delivered in vivo. The integration of RLRs agonism with RNA interference or CAR-T cells provides new dimensions that complement cancer immunotherapy. Moreover, we update the progress of recent clinical trials for cancer therapy involving RLRs activation and immune modulation. Further studies of the mechanisms underlying RLRs signaling will shed new light on the development of cancer therapeutics. Manipulation of RLRs signaling represents an opportunity for clinically relevant cancer therapy. Addressing the challenges in this field will help develop future generations of cancer immunotherapy.

Escaping Death: How Cancer Cells and Infected Cells Resist Cell-Mediated Cytotoxicity

Cytotoxic lymphocytes are critical in our immune defence against cancer and infection. Cytotoxic T lymphocytes and Natural Killer cells can directly lyse malignant or infected cells in at least two ways: granule-mediated cytotoxicity, involving perforin and granzyme B, or death receptor-mediated cytotoxicity, involving the death receptor ligands, tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand (FasL). In either case, a multi-step pathway is triggered to facilitate lysis, relying on active pro-death processes and signalling within the target cell. Because of this reliance on an active response from the target cell, each mechanism of cell-mediated killing can be manipulated by malignant and infected cells to evade cytolytic death. Here, we review the mechanisms of cell-mediated cytotoxicity and examine how cells may evade these cytolytic processes. This includes resistance to perforin through degradation or reduced pore formation, resistance to granzyme B through inhibition or autophagy, and resistance to death receptors through inhibition of downstream signalling or changes in protein expression. We also consider the importance of tumour necrosis factor (TNF)-induced cytotoxicity and resistance mechanisms against this pathway. Altogether, it is clear that target cells are not passive bystanders to cell-mediated cytotoxicity and resistance mechanisms can significantly constrain immune cell-mediated killing. Understanding these processes of immune evasion may lead to novel ideas for medical intervention.

Optimizing NK-92 serial killers: gamma irradiation, CD95/Fas-ligation, and NK or LAK attack limit cytotoxic efficacy

BACKGROUND

The NK cell line NK-92 and its genetically modified variants are receiving attention as immunotherapies to treat a range of malignancies. However, since NK-92 cells are themselves tumors, they require irradiation prior to transfer and are potentially susceptible to attack by patients' immune systems. Here, we investigated NK-92 cell-mediated serial killing for the effects of gamma-irradiation and ligation of the death receptor Fas (CD95), and NK-92 cell susceptibility to attack by activated primary blood NK cells.

METHODS

To evaluate serial killing, we used 51Cr-release assays with low NK-92 effector cell to target Raji, Daudi or K562 tumor cell (E:T) ratios to determine killing frequencies at 2-, 4-, 6-, and 8-h.

RESULTS

NK-92 cells were able to kill up to 14 Raji cells per NK-92 cell in 8 h. NK-92 cells retained high cytotoxic activity immediately after irradiation with 10 Gy but the cells surviving irradiation lost > 50% activity 1 day after irradiation. Despite high expression of CD95, NK-92 cells maintained their viability following overnight Fas/CD95-ligation but lost some cytotoxic activity. However, 1 day after irradiation, NK-92 cells were more susceptible to Fas ligation, resulting in decreased cytotoxic activity of the cells surviving irradiation. Irradiated NK-92 cells were also susceptible to killing by both unstimulated and IL-2 activated primary NK cells (LAK). In contrast, non-irradiated NK-92 cells were more resistant to attack by NK and LAK cells.

CONCLUSIONS

Irradiation is deleterious to both the survival and cytotoxicity mediated by NK-92 cells and renders the NK-92 cells susceptible to Fas-initiated death and death initiated by primary blood NK cells. Therefore, replacement of irradiation as an antiproliferative pretreatment and genetic deletion of Fas and/or NK activation ligands from adoptively transferred cell lines are indicated as new approaches to increase therapeutic efficacy.

Overview of serpin B9 and its roles in cancer (Review)

Serine proteinase inhibitor B9 (serpin B9) is a member of the serine protease inhibitor superfamily, which is widely found in animals, plants and microorganisms. Serpin B9 has been reported to protect cells from the immune‑killing effect of granzyme B (GrB) released by lymphocytes. In recent years, an increasing number of studies have indicated that serpin B9 is involved in tumour apoptosis, immune evasion, tumorigenesis, progression, metastasis, drug resistance and even in maintaining the stemness of cancer stem cells (CSCs). Moreover, according to clinical studies, serpin B9 has been demonstrated to be significantly associated with the development of precancerous lesions, a poor prognosis and ineffective therapies, suggesting that serpin B9 may be a potential target for cancer treatment and an indicator of cancer diagnosis; thus, it has begun to attract increased attention from scholars. The present review concisely described the structure and biological functions of the serpin superfamily and serpin B9. In addition, related research on serpins in cancer is discussed in order to provide a comprehensive understanding of the role of serpin B9 in cancer, as well as its clinical significance for cancer diagnosis and prognosis.

Interaction Networks Converging on Immunosuppressive Roles of Granzyme B: Special Niches Within the Tumor Microenvironment

Granzyme B is a renowned effector molecule primarily utilized by CTLs and NK cells against ill-defined and/or transformed cells during immunosurveillance. The overall expression of granzyme B within tumor microenvironment has been well-established as a prognostic marker indicative of priming immunity for a long time. Until recent years, increasing immunosuppressive effects of granzyme B are unveiled in the setting of different immunological context. The accumulative evidence confounded the roles of granzyme B in immune responses, thereby arousing great interests in characterizing detailed feature of granzyme B-positive niche. In this paper, the granzyme B-related regulatory effects of major suppressor cells as well as the tumor microenvironment that defines such functionalities were longitudinally summarized and discussed. Multiplex networks were built upon the interactions among different transcriptional factors, cytokines, and chemokines that regarded to the initiation and regulation of granzyme B-mediated immunosuppression. The conclusions and prospect may facilitate better interpretations of the clinical significance of granzyme B, guiding the rational development of therapeutic regimen and diagnostic probes for anti-tumor purposes.

Challenges for Immunotherapy in Multiple Myeloma: Bone Marrow Microenvironment-Mediated Immune Suppression and Immune Resistance

The power of immunotherapy in the battle of Multiple Myeloma (MM) started with allogeneic stem cell transplantation, and was rediscovered with immunomodulatory drugs and extended with the outstanding results achieved with targeted antibodies. Today, next to powerful antibodies Elotuzumab and Daratumumab, several T-cell-based immunotherapeutic approaches, such as bispecific antibodies and chimeric antigen receptor-transduced T-cells (CAR T-cells) are making their successful entry in the immunotherapy arena with highly promising results in clinical trials. Nonetheless, similar to what is observed in chemotherapy, MM appears capable to escape from immunotherapy, especially through tight interactions with the cells of the bone marrow microenvironment (BM-ME). This review will outline our current understanding on how BM-ME protects MM-cells from immunotherapy through immunosuppression and through induction of intrinsic resistance against cytotoxic effector mechanisms of T- and NK-cells.

Overexpression of proteinase inhibitor 9 is associated with poor prognosis in human hepatocellular carcinoma and with proliferation and apoptosis in HepG2 cells in vitro

Excessive proteinase inhibitor 9 (PI9) levels predict a poor outcome for patients with several tumor types. We compared the expression of PI9 in HepG2 cells and in 21 pairs of tumor and peritumor tissue samples using western blotting. Immunohistochemical staining was used to detect PI9 expression in 105 cases of hepatocellular carcinoma (HCC) and in 20 adjacent normal liver tissues. Changes in the degree of apoptosis and proliferation were determined before and after transfection with pcDNA3.1-PI9 and small interfering (si)RNA-PI9 using MTT analysis, colony formation assay, and flow cytometry. The correlation between PI9 expression and prognosis was determined in a large HCC patient cohort (n=105). Western blotting showed that PI9 expression was significantly higher in tumor tissues than in adjacent tissues. PI9 immunohistochemical staining was positive in 78.1% of HCC tissues, which was significantly higher than that seen in adjacent normal liver tissue (35%). PI9 expression in HCC correlated closely with the extent of tumor differentiation, tumor-node-metastasis staging, and tumor size. Cox regression analysis demonstrated that PI9 is an independent predictor of prognosis in patients with HCC, and is related to overall survival. The apoptosis of HepG2 cells was significantly increased following PI9 up-regulation and significantly decreased after siRNA interference against PI9 expression. Cell proliferation was significantly decreased following PI9 up-regulation and significantly increased after siRNA interference of PI9 expression. PI9 appears to contribute to the apoptosis of HCC, and could be an independent predictor of recurrence and a suitable pharmaceutical target in patients with HCC.

Type I IFN protects cancer cells from CD8+ T cell-mediated cytotoxicity after radiation

Treatment of tumors with ionizing radiation stimulates an antitumor immune response partly dependent on induction of IFNs. These IFNs directly enhance dendritic cell and CD8+ T cell activity. Here we show that resistance to an effective antitumor immune response is also a result of IFN signaling in a different cellular compartment of the tumor, the cancer cells themselves. We abolished type I IFN signaling in cancer cells by genetic elimination of its receptor, IFNAR1. Pronounced immune responses were provoked after ionizing radiation of tumors from 4 mouse cancer cell lines with Ifnar1 knockout. This enhanced response depended on CD8+ T cells and was mediated by enhanced susceptibility to T cell-mediated killing. Induction of Serpinb9 proved to be the mechanism underlying control of susceptibility to T cell killing after radiation. Ifnar1-deficient tumors had an augmented response to anti-PD-L1 immunotherapy with or without radiation. We conclude that type I IFN can protect cancer cells from T cell-mediated cytotoxicity through regulation of Serpinb9. This result helps explain why radiation of tumors can stimulate antitumor immunity yet also result in resistance. It further suggests potential targets for intervention to improve therapy and to predict responses.

Early synergistic interactions between the HPV16‑E7 oncoprotein and 17β-oestradiol for repressing the expression of Granzyme B in a cervical cancer model

Although high-risk human papillomavirus (HR‑HPV) infection has a prominent role in the aetiology of cervical cancer (CC), sex steroid hormones may also be involved in this process; however, the cooperation between oestrogen and HR‑HPV in the early stages of cervical carcinogenesis is poorly understood. Since 17β-oestradiol (E2) and the HPV type 16‑E7 oncoprotein induce CC in transgenic mice, a microarray analysis was performed in the present study to generate global gene expression profiles from 2‑month‑old FVB (non‑transgenic) and K14E7 (transgenic) mice who were left untreated or were treated for 1 month with E2. Upregulation of cancer-related genes that have not been previously reported in the context of CC, including glycerophosphodiester phosphodiesterase domain containing 3, interleukin 1 receptor type II, natriuretic peptide type C, MGAT4 family member C, lecithin-retinol acyltransferase (phosphatidylcholine-retinol-O-acyltransferase) and glucoside xylosyltransferase 2, was observed. Notably, upregulation of the serine (or cysteine) peptidase inhibitor clade B member 9 gene and downregulation of the Granzyme gene family were observed; the repression of the Granzyme B pathway may be a novel mechanism of immune evasion by cancer cells. The present results provide the basis for further studies on early biomarkers of CC risk and synergistic interactions between HR‑HPV and oestrogen.

Immune surveillance in melanoma: From immune attack to melanoma escape and even counterattack

Pharmacologic inhibition of the cytotoxic T lymphocyte antigen 4 (CTLA4) and the programmed death receptor-1 (PD1) has resulted in unprecedented durable responses in metastatic melanoma. However, resistance to immunotherapy remains a major challenge. Effective immune surveillance against melanoma requires 4 essential steps: activation of the T lymphocytes, homing of the activated T lymphocytes to the melanoma microenvironment, identification and episode of melanoma cells by activated T lymphocytes, and the sensitivity of melanoma cells to apoptosis. At each of these steps, there are multiple factors that may interfere with the immune surveillance machinery, thus allowing melanoma cells to escape immune attack and develop resistance to immunotherapy. We provide a comprehensive review of the complex immune surveillance mechanisms at play in melanoma, and a detailed discussion of how these mechanisms may allow for the development of intrinsic or acquired resistance to immunotherapeutic modalities, and potential avenues for overcoming this resistance.

Heterogeneous yet stable Vδ2(+) T-cell profiles define distinct cytotoxic effector potentials in healthy human individuals

Human γδ T cells display potent responses to pathogens and malignancies. Of particular interest are those expressing a γδ T-cell receptor (TCR) incorporating TCRδ-chain variable-region-2 [Vδ2⁽⁺⁾], which are activated by pathogen-derived phosphoantigens (pAgs), or host-derived pAgs that accumulate in transformed cells or in cells exposed to aminobisphosphonates. Once activated, Vδ2⁽⁺⁾ T cells exhibit multiple effector functions that have made them attractive candidates for immunotherapy. Despite this, clinical trials have reported mixed patient responses, highlighting a need for better understanding of Vδ2⁽⁺⁾ T-cell biology. Here, we reveal previously unappreciated functional heterogeneity between the Vδ2⁽⁺⁾ T-cell compartments of 63 healthy individuals. In this cohort, we identify distinct "Vδ2 profiles" that are stable over time; that do not correlate with age, gender, or history of phosphoantigen activation; and that develop after leaving the thymus. Multiple analyses suggest these Vδ2 profiles consist of variable proportions of two dominant but contrasting Vδ2⁽⁺⁾ T-cell subsets that have divergent transcriptional programs and that display mechanistically distinct cytotoxic potentials. Importantly, an individual's Vδ2 profile predicts defined effector capacities, demonstrated by contrasting mechanisms and efficiencies of killing of a range of tumor cell lines. In short, these data support patient stratification to identify individuals with Vδ2 profiles that have effector mechanisms compatible with tumor killing and suggest that tailored Vδ2-profile-specific activation protocols may maximize the chances of future treatment success.

The analysis of estrogen receptor-α positive breast cancer stem-like cells unveils a high expression of the serpin proteinase inhibitor PI-9: Possible regulatory mechanisms

Breast cancer stem cells seem to play important roles in breast tumor recurrence and endocrine therapy resistance, although the underlying mechanisms have not been well established. Moreover, in some tumor systems the immunosurveillance failure against cancer cells has been related to the presence of the granzyme B inhibitor PI-9. This study explored the status of PI-9 in tumorspheres isolated from estrogen receptor-α positive (ERα+) breast cancer MCF7 cells. Studies were performed in tertiary tumorspheres which possess high levels of stemness markers (Nanog, Oct3/4 and Sox2) and self-renewal ability. The exposure to estrogens (17-β estradiol and genistein) increased the number and sizes of tumorspheres, promoting cell proliferation as demonstrated by the increase in the proliferating cell nuclear antigen (PCNA). The study of the three isoforms (66, 46 and 36 kDa) of ERα disclosed that tertiary tumorspheres exhibit a marked increase in ERα36, while the level of ERα66, which is highly expressed in MCF7 cells, declines. Although it is known that PI-9 is a transcriptional target of ERα66, surprisingly in tertiary tumorspheres, despite the reduced level of ERα66, the protein and mRNA content of PI-9 is higher than in MCF7 cells. Treatment with estrogens further increased PI-9 level while decreased that of ERα66 isoform thus excluding the involvement of this receptor isoform in the event. Moreover, our studies also provided evidence that tertiary tumorspheres express elevated levels of CXCR4 and phospho-p38, suggesting that the high PI-9 content might be ascribed to the activation of the proliferative CXCR4/phospho-p38 axis. Taken together, these events could supply a selective advantage to breast cancer stem cells by interfering with immunosurveillance systems and open up the avenue to new possible targets for breast cancer treatment.

NK cell genotype and phenotype at diagnosis of acute lymphoblastic leukemia correlate with postinduction residual disease

PURPOSE

Not all natural killer (NK) cells are equally cytotoxic against leukemia because of differences in receptor gene content and surface expression. We correlated NK cell genotype and phenotype at diagnosis of childhood acute lymphoblastic leukemia (ALL) with minimal residual disease (MRD) after induction chemotherapy.

EXPERIMENTAL DESIGN

The NK cells and leukemia blasts of 244 patients were analyzed at diagnosis by killer-cell immunoglobulin-like receptor (KIR) typing and immunophenotyping. The results were correlated statistically with postinduction MRD status.

RESULTS

The odds of being MRD positive in patients with KIR telomeric (Tel)-A/B genotype were 2.85 times the odds in those with Tel-A/A genotype (P = 0.035). MRD-positive patients were more likely to have KIR2DL5A (P = 0.006) and expressed less activating receptor NKp46 and FASL on their NK cells (P = 0.0074 and P = 0.029, respectively). The odds of being MRD positive increased by 2.01-fold for every percentage increase in NK cells expressing KIR2DL1 in the presence of HLA-C2 ligand (P = 0.034). The quantity of granzyme B inhibitor PI-9 in the leukemia blasts was greater in patients who were MRD positive (P = 0.038). Collectively, five NK cell-related factors (Tel-B-associated KIR2DL5A, NKp46, FASL, granzyme B, and PI-9) are strongly associated with MRD positivity at the end of induction with 100% sensitivity and 80% specificity.

CONCLUSIONS

Our data support the hypothesis that NK cells with a strong effector phenotype in the setting of decreased leukemia resistance are associated with better leukemia control.

Development of human serine protease-based therapeutics targeting Fn14 and identification of Fn14 as a new target overexpressed in TNBC

The cytokine TWEAK and its receptor, Fn14, have emerged as potentially valuable targets for cancer therapy. Granzyme B (GrB)-containing Fn14-targeted constructs were generated containing either the Fn14 ligand TWEAK (GrB-TWEAK) or an anti-Fn14 humanized single-chain antibody (GrB-Fc-IT4) as the targeting moieties. Both constructs showed high affinity and selective cytotoxicity against a panel of Fn14-expressing human tumor cells including triple-negative breast cancer (TNBC) lines. Cellular expression of the GrB inhibitor PI-9 in target cells had no impact on the cytotoxic effect of either construct. Cellular expression of MDR1 showed no cross-resistance to the fusion constructs. GrB-TWEAK and GrB-Fc-IT4 activated intracellular caspase cascades and cytochrome c-related proapoptotic pathways consistent with the known intracellular functions of GrB in target cells. Treatment of mice bearing established HT-29 xenografts with GrB-TWEAK showed significant tumor growth inhibition compared with vehicle alone (P < 0.05). Both GrB-TWEAK and GrB-Fc-IT4 displayed significant tumor growth inhibition when administered to mice bearing orthotopic MDA-MB-231 (TNBC) tumor xenografts. The Cancer Genome Atlas analysis revealed that Fn14 mRNA expression was significantly higher in TNBC and in HER2-positive disease (P < 0.0001) compared with hormone receptor-positive breast cancer, and in basal-like 2 tumors (P = 0.01) compared with other TNBC molecular subtypes. IHC analysis of a 101 patient TNBC tumor microarray showed that 55 of 101 (54%) of tumors stained positive for Fn14, suggesting that this may be an excellent potential target for precision therapeutic approaches. Targeting Fn14 using fully human, GrB-containing fusion constructs may form the basis for a new class of novel, potent, and highly effective constructs for targeted therapeutic applications.

Quantitative analysis of resistance to natural killer attacks reveals stepwise killing kinetics

Molecular mechanisms can protect cancer cells from immune attacks. At the level of bulk tissue, these survival mechanisms are often indistinguishable and simply appear as reduced cell death. However, by tracking individual cell survival and death times, we found broad variation in the kinetics of immune evasion. In response to attacks by natural killer cells, we observed that some cancer lines exhibited exponential survival time distributions. Slowly killed cancer lines had reduced exponential rate constants. In contrast, a line engineered to express the serpin protein PI-9, which is known to promote resistance to immune killing, exhibited a markedly nonexponential survival time distribution. By following the histories of individual cancer cells with multiplexed reporters, we obtained evidence that two or more immune attacks are likely required to kill serpin-expressing cells. Thus, resistance is a finite and measurable quantity, with a distinct kinetic signature. A quantitative model based on independently measured parameters is consistent with our conclusions.

Systematic genetic analysis identifies Cis-eQTL target genes associated with glioblastoma patient survival

Prior expression quantitative trait locus (eQTL) studies have demonstrated heritable variation determining differences in gene expression. The majority of eQTL studies were based on cell lines and normal tissues. We performed cis-eQTL analysis using glioblastoma multiforme (GBM) data sets obtained from The Cancer Genome Atlas (TCGA) to systematically investigate germline variation's contribution to tumor gene expression levels. We identified 985 significant cis-eQTL associations (FDR<0.05) mapped to 978 SNP loci and 159 unique genes. Approximately 57% of these eQTLs have been previously linked to the gene expression in cell lines and normal tissues; 43% of these share cis associations known to be associated with functional annotations. About 25% of these cis-eQTL associations are also common to those identified in Breast Cancer from a recent study. Further investigation of the relationship between gene expression and patient clinical information identified 13 eQTL genes whose expression level significantly correlates with GBM patient survival (p<0.05). Most of these genes are also differentially expressed in tumor samples and organ-specific controls (p<0.05). Our results demonstrated a significant relationship of germline variation with gene expression levels in GBM. The identification of eQTLs-based expression associated survival might be important to the understanding of genetic contribution to GBM cancer prognosis.

The immune system and inflammation in breast cancer

During different stages of tumor development the immune system can either identify and destroy tumors, or promote their growth. Therapies targeting the immune system have emerged as a promising treatment modality for breast cancer, and immunotherapeutic strategies are being examined in preclinical and clinical models. However, our understanding of the complex interplay between cells of the immune system and breast cancer cells is incomplete. In this article, we review recent findings showing how the immune system plays dual host-protective and tumor-promoting roles in breast cancer initiation and progression. We then discuss estrogen receptor α (ERα)-dependent and ERα-independent mechanisms that shield breast cancers from immunosurveillance and enable breast cancer cells to evade immune cell induced apoptosis and produce an immunosuppressive tumor microenvironment. Finally, we discuss protumorigenic inflammation that is induced during tumor progression and therapy, and how inflammation promotes more aggressive phenotypes in ERα positive breast cancers.

Decreased Expression of Protease Inhibitor 9, a Granzyme B Inhibitor, in Celiac Disease: A Potential Mechanism in Enterocyte Destruction and Villous Atrophy

The objective of this study was to assess the expression of protease inhibitor 9, a granzyme B inhibitor, in human small intestine, and to evaluate its cytoprotective role in the celiac disease of children. Twelve subjects with untreated celiac disease and thirteen healthy controls were examined by endoscopy. The expression of protease inhibitor 9 was analyzed immunohistochemically from duodenal biopsies and compared to granzyme B expression, apoptosis rate, number of intraepithelial lymphocytes and villus and crypt height data from the biopsies. We discovered that protease inhibitor 9 is expressed in the cytoplasm of the duodenal epithelial cells in the majority of cases. The enterocyte expression of protease inhibitor 9 was lower in celiac disease patients than in controls. Protease inhibitor 9 expression also showed a negative correlation with the number of apoptotic cells, overall density of granzyme B expressing intraepithelial lymphocytes, the height of the crypts and the severity of villous atrophy in duodenum. Therefore, we conclude that the protease inhibitor 9 is constantly expressed in the enterocytes of normal duodenum and the expression is decreased in celiac disease. These findings suggest that protease inhibitor 9 has a role in duodenal homeostasis and in the protection of enterocytes from misdirected granzyme B. Indeed, observed associations of lowered protease inhibitor 9 expression together with increased granzyme B expression, apoptosis rate and severity of villous atrophy suggest that impaired balance between granzyme B mediated cytotoxicity and its inhibition by protease inhibitor 9 forms an important factor in the pathogenesis of villous atrophy in celiac disease.

SerpinB9 expression in human renal tubular epithelial cells is induced by triggering of the viral dsRNA sensors TLR3, MDA5 and RIG-I

BACKGROUND

Serine protease inhibitor B9 (serpinB9) protects against granzyme B-mediated apoptosis and could help to reduce tubular damage under inflammatory conditions like interstitial nephritis. Previously, we found that tubular serpinB9 expression was increased during subclinical rejection. Here, we studied the regulation of serpinB9 expression in tubular epithelial cells (TECs) under inflammatory conditions.

METHODS

SerpinB9 expression was analysed on messenger RNA (mRNA), and protein levels in primary human TECs were stimulated with various cytokines and pattern recognition receptor ligands and in kidney transplant biopsies obtained during different types of viral infection.

RESULTS

Of the inflammatory stimuli tested, only the double-stranded RNA (dsRNA) analogue poly(I:C) promoted serpinB9 mRNA and protein expression. We found that TECs express the viral dsRNA receptors Toll-like receptor 3 (TLR3), melanoma differentiation-associated gene 5 (MDA5) and retinoic acid-inducible gene-I (RIG-I). dsRNA receptor ligands enhanced serpinB9 expression, which involved nuclear factor-kappaB (NF-κB) activation, did not require Type I interferon production and was a direct result of dsRNA receptor-induced gene transcription. In kidney transplants, serpinB9 transcription was increased during infection with cytomegalovirus, Epstein-Barr virus or BK virus compared to stable grafts. Immunohistochemistry showed that tubuli and lymphocytes expressed the inhibitor.

CONCLUSION

SerpinB9 expression in human TECs is induced by triggering of the viral dsRNA sensors TLR3, MDA5 and RIG-I. Viral dsRNA may increase the threshold for granzyme B-mediated apoptosis in TECs via serpinB9 upregulation and thus help to protect the kidney against cytotoxic insults during viral infection.

Inhibition of Granzyme B by PI-9 protects prostate cancer cells from apoptosis

BACKGROUND

In order for tumors to grow and proliferate, they must avoid recognition by immune cells and subsequent death by apoptosis. Granzyme B (GrB), a protease located in natural killer cells, initiates apoptosis in target cells. Inhibition of GrB by PI-9, its natural inhibitor, can prevent apoptosis. Here we investigate whether PI-9 protects prostate cancer cells from apoptosis.

METHODS

The expression of PI-9 was quantified by qPCR in several prostate cancer cell lines, and GrB activity was tested in each cell line. PI-9 was overexpressed in LNCaP cells, which lack endogenous PI-9. Apoptosis was induced by natural killer cells in LNCaP cells that either contained or lacked PI-9, and the percent cell death was quantified. Lastly, PI-9 levels were examined by qPCR and immunohistochemistry in prostate tumor tissue.

RESULTS

Prostate cancer cell lines that expressed PI-9 could inhibit GrB. Overexpression of PI-9 protected LNCaP cells from natural killer cell-mediated apoptosis. Examination of the levels of PI-9 in tissue from prostate tumors showed that PI-9 could be upregulated in low grade tumors and stochastically dysregulated in high grade tumors. Additionally, PI-9 was found consistently in high grade prostatic intraepithelial neoplasia and atrophic lesions.

CONCLUSIONS

These results indicate that overexpression of PI-9 can protect prostate cancer cells from apoptosis, and this effect may occur in human prostate tumors. These findings imply that early prostatic inflammation may trigger this increase in PI-9. This suggests that PI-9 upregulation is needed early in tumor progression, before additional protective mechanisms are in place.

Stromal cell-based immunotherapy in transplantation

Organs are composed of parenchymal cells that characterize organ function and nonparenchymal cells that are composed of cells in transit, as well as tissue connective tissue, also referred to as tissue stromal cells. It was originally thought that these tissue stromal cells provided only structural and functional support for parenchymal cells and were relatively inert. However, we have come to realize that tissue stromal cells, not restricted to in the thymus and lymphoid organs, also play an active role in modulating the immune system and its response to antigens. The recognition of these elements and the elucidation of their mechanisms of action have provided valuable insight into peripheral immune regulation. Extrapolation of these principles may allow us to utilize their potential for clinical application. In this article, we will summarize a number of tissue stromal elements/cell types that have been shown to induce hyporesponsiveness to transplants. We will also discuss the mechanisms by which these stromal cells create a tolerogenic environment, which in turn results in long-term allograft survival.

Anti-inflammatory properties of exenatide in human pancreatic islets

Exenatide is an analog of the incretin hormone glucagon-like peptide (GLP-1) that is used for the treatment of T2D for their metabolic effects. In addition to its insulinotropic effects, exenatide increases functional islet mass and improves their survival. Improved outcomes have been reported in recent clinical islet transplantation trials for the treatment of type 1 diabetes. The purpose of this study was to investigate whether exenatide has anti-inflammatory properties in human islets. Exenatide treatment improved islet function, significantly reduced content of inflammation-related molecules (tissue factor, IFN-γ, IL-17, IL-1β, and IL-2) and caspase 3 activation, whereas increased phosphorylation of ERK1/2, STAT3, and Akt in vitro. Immunostaining showed expression of GLP-1R in β-cells but not in α-cells. IL-1β colocalized with GLP-1R in β-cells. Induction of serine proteinase inhibitor 9 (PI-9) was detected after exposure of human islets to exenatide in vitro and after transplantation into immunodeficient mice. GLP-1 induced PI-9 expression in vitro but to a lower extent than exenatide. This effect was partially blocked by the antagonist exendin-9 in vitro. As assessed by immunostaining PI-9 is mostly expressed in β-cells but not in α-cells. In conclusion, we describe anti-inflammatory and cytoprotective properties of exenatide in human islets. Exenatide-mediated PI-9 expression, the only known granzyme B inhibitor, unveils potential immunoregulatory properties.

A noncompetitive small molecule inhibitor of estrogen-regulated gene expression and breast cancer cell growth that enhances proteasome-dependent degradation of estrogen receptor {alpha}

The mechanisms responsible for 17β-estradiol (E(2))-stimulated breast cancer growth and development of resistance to tamoxifen and other estrogen receptor α (ERα) antagonists are not fully understood. We describe a new tool for dissecting ERα action in breast cancer, p-fluoro-4-(1,2,3,6,-tetrahydro-1,3-dimethyl-2-oxo-6-thionpurin-8-ylthio) (TPSF), a potent small-molecule inhibitor of estrogen receptor α that does not compete with estrogen for binding to ERα. TPSF noncompetitively inhibits estrogen-dependent ERα-mediated gene expression with little inhibition of transcriptional activity by NF-κB or the androgen or glucocorticoid receptor. TPSF inhibits E(2)-ERα-mediated induction of the proteinase inhibitor 9 gene, which is activated by ERα binding to estrogen response element DNA, and the cyclin D1 gene, which is induced by tethering ERα to other DNA-bound proteins. TPSF inhibits anchorage-dependent and anchorage-independent E(2)-ERα-stimulated growth of MCF-7 cells but does not inhibit growth of ER-negative MDA-MB-231 breast cancer cells. TPSF also inhibits ERα-dependent growth in three cellular models for tamoxifen resistance; that is, 4-hydroxytamoxifen-stimulated MCF7ERαHA cells that overexpress ERα, fully tamoxifen-resistant BT474 cells that have amplified HER-2 and AIB1, and partially tamoxifen-resistant ZR-75 cells. TPSF reduces ERα protein levels in MCF-7 cells and several other cell lines without altering ERα mRNA levels. The proteasome inhibitor MG132 abolished down-regulation of ERα by TPSF. Thus, TPSF affects receptor levels at least in part due to its ability to enhance proteasome-dependent degradation of ERα. TPSF represents a novel class of ER inhibitor with significant clinical potential.

Validation of noninvasive diagnosis of BK virus nephropathy and identification of prognostic biomarkers

BACKGROUND

BK virus nephropathy (BKVN) may cause renal allograft dysfunction and failure. The gold standard test is kidney biopsy, which is invasive and costly. A noninvasive, accurate biomarker for diagnosis of BKVN and prognostication of allograft function after BKVN infection may improve allograft survival.

METHODS

We tested the diagnostic accuracy of our previously reported cutoff value of 6.5x10(5) BKV viral capsid protein 1 (VP-1) mRNA/ng RNA in urinary cells (Ding et al., Transplantation 2002; 74: 987) using an independent cohort (n=89). We also examined whether urinary cell mRNA profiles obtained at the time of BKVN diagnosis identified patients at risk of subsequent decline in graft function.

RESULTS

BKVN was accurately diagnosed (sensitivity of 100% and specificity of 97%) using our previously reported cutoff value. Levels of granzyme B (GB) mRNA (P=0.002) and proteinase inhibitor (PI)-9 mRNA (P=0.01) in urinary cells were higher in BKVN patients with a subsequent decline in renal function (n=8) compared with patients with stable function (n=10), and were positively associated (GB, P=0.01; PI-9, P=0.04) with rise in serum creatinine from the time of BKVN diagnosis to 12 months after diagnosis. GB levels in the BKVN patients with a decline in renal function were similar to those in the acute rejection group (n=11, P>0.05), but higher than the normal biopsy group (n=36, P<0.001); levels in BKVN patients with stable function were lower than those in the acute rejection group (P<0.01) and not significantly different from the normal biopsy group (P>0.05).

CONCLUSIONS

Noninvasive diagnosis of BKVN and prognostication of renal allograft function after BKVN diagnosis are feasible by measurement of transcripts for BKV viral capsid protein 1 (VP-1), GB, and PI-9 in urine.

Antigen-specific cytotoxicity by invariant NKT cells in vivo is CD95/CD178-dependent and is correlated with antigenic potency

Invariant NKT (iNKT) cells are a unique subset of T lymphocytes that rapidly carry out effector functions following activation with glycolipid Ags, such as the model Ag alpha-galactosylceramide. Numerous studies have investigated the mechanisms leading to Th1 and Th2 cytokine production by iNKT cells, as well as the effects of the copious amounts of cytokines these cells produce. Less is known, however, about the mechanisms of iNKT cell cytotoxicity. In this study, we investigated the effect of Ag availability and strength, as well as the molecules involved in iNKT cytotoxicity. We demonstrate that the iNKT cell cytotoxicity in vivo correlates directly with the amount of CD1d expressed by the targets as well as the TCR affinity for the target glycolipid Ag. iNKT cells from spleen, liver, and thymus were comparable in their cytotoxicity in vitro. Surprisingly, we show that the Ag-specific cytotoxicity of iNKT cells in vivo depended almost exclusively on the interaction of CD95 (Fas) with CD178 (FasL), and that this mechanism can be efficiently used for tumor protection. Therefore, unlike NK cells, which rely mostly on perforin/granzyme-mediated mechanisms, the Ag-specific cytotoxicity of iNKT cells in vivo is largely restricted to the CD95/CD178 pathway.

Immunoprotective Sertoli cells: making allogeneic and xenogeneic transplantation feasible

The testis as an immune-privileged site allows long-term survival of allogeneic and xenogeneic transplants. Testicular Sertoli cells (SCs) play a major role in this immunoprotection and have been used to create an ectopic immune-privileged environment that prolongs survival of co-transplanted allogeneic and xenogeneic cells, including pancreatic islets and neurons. Extended survival of such grafts testifies to the immunoprotective properties of SCs. However, there is still variability in the survival rates of the co-grafted cells and rarely are 100% of the grafts protected. This emphasizes the need to learn more about what is involved in creating the optimal immunoprotective milieu. Several parameters including organization of the SCs into tubule-like structures and the production of immunomodulatory factors by SCs, specifically complement inhibitors, cytokines, and cytotoxic lymphocyte inhibitors, are likely important. In addition, an intricate interplay between several of these factors may be responsible for providing the most ideal environment for protection of the co-transplants by SCs. In this review, we will also briefly describe a novel use for the immune-privileged abilities of SCs; engineering them to deliver therapeutic proteins for the treatment of diseases like diabetes and Parkinson's disease. In conclusion, further studies and more detailed analysis of the mechanisms involved in creating the immune-protective environment by SCs may make their application in co-transplantation and as engineered cells clinically feasible.

Anti-perforin neutralizing antibody reduces myocardial injury in viral myocarditis

AIM

To investigate the role of anti-perforin neutralizing antibody in viral myocarditis.

METHODS

We divided 45 Balb/c mice randomly into 3 groups, a normal control group, a control group inoculated with coxsackie virus B3, and a group inoculated with anti-perforin neutralizing antibody. The second group was inoculated with 0.15 milliliters coxsackie virus B3, and the third group additionally with 0.1 milligrams/kilogram anti-perforin neutralizing antibody at time points of 6 hours and 3 days after infection. Histopathology was performed using haematoxylin and eosin, with apoptosis examined by the terminal transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick, end-labeling method, or Tunel. The expression of caspase-3 in myocardium was investigated by immunohistochemistry and reverse-transcription polymerase chain reaction.

RESULTS

The pathologic score, myocardial viral titers, average percentages of apoptotic cardiomyocytes, expression of active caspase-3 protein and messenger ribonucleic acid in the myocardium of the mice receiving anti-PFP neutralizing antibody therapy were all significantly reduced when compared to values from the group inoculated with coxsackie virus B3. The rates of expression of Caspase-3 and myocardial apoptosis were positively correlated with the scores for myocardial pathology.

CONCLUSION

Our results suggest that anti- perforin neutralizing antibody can reduce the myocardial damage by blocking the perforin/granzyme pathway, and downregulating the expression of messenger ribonucleic acid and protein of Caspase-3. These approaches may offer promising novel therapeutic strategies for the clinical treatment of viral myocarditis.

Low concentrations of the soy phytoestrogen genistein induce proteinase inhibitor 9 and block killing of breast cancer cells by immune cells

The risks and benefits of diets and supplements containing the estrogenic soy isoflavone genistein are not well established. We report that 10 nm genistein potently induces the granzyme B inhibitor, proteinase inhibitor 9 (PI-9) in MCF-7 human breast cancer cells. By inducing PI-9, genistein inhibits the ability of human natural killer (NK) cells to lyse the target breast cancer cells. In ERalphaHA cells, stably transfected MCF-7 cells, which contain elevated levels of estrogen receptor-alpha (ERalpha), 100 pm genistein or 17beta-estradiol potently induce PI-9 and prevent NK cells from killing the target breast cancer cells. The concentrations of genistein that fully induce PI-9 in MCF-7 cells, and in ERalphaHA cells, are far lower than those previously reported to elicit estrogenic responses through ERalpha. Because 4-hydroxytamoxifen, raloxifene, and ICI 182,780/Faslodex all block genistein induction of PI-9 and elevated levels of ERalpha enhance induction of PI-9, genistein acts via ERalpha to induce PI-9. Increasing levels of ERalpha in breast cancer cells results in a progressive increase in induction of PI-9 by genistein and in the cell's ability to evade killing by NK cells. Moderate levels of dietary genistein and soy flour effectively induce PI-9 in human breast cancers grown in ovariectomized athymic mice. A significant population consumes levels of genistein in soy products that may be high enough to induce PI-9, perhaps potentiating the survival of some preexisting breast cancers by enabling them to evade immunosurveillance.

A new small molecule inhibitor of estrogen receptor alpha binding to estrogen response elements blocks estrogen-dependent growth of cancer cells

Estrogen receptor alpha (ERalpha) plays an important role in several human cancers. Most current ERalpha antagonists bind in the receptor ligand binding pocket and compete for binding with estrogenic ligands. Instead of the traditional approach of targeting estrogen binding to ER, we describe a strategy using a high throughput fluorescence anisotropy microplate assay to identify small molecule inhibitors of ERalpha binding to consensus estrogen response element (cERE) DNA. We identified small molecule inhibitors of ERalpha binding to the fluorescein-labeled (fl)cERE and evaluated their specificity, potency, and efficacy. One small molecule, theophylline, 8-[(benzylthio)methyl]-(7CI,8CI) (TPBM), inhibited ERalpha binding to the flcERE (IC(50) approximately 3 microm) and inhibited ERalpha-mediated transcription of a stably transfected ERE-containing reporter gene. Inhibition by TPBM was ER-specific, because progesterone and glucocorticoid receptor transcriptional activity were not significantly inhibited. In tamoxifen-resistant breast cancer cells that overexpress ERalpha, TPBM inhibited 17beta-estradiol (E(2))-ERalpha (IC(50) 9 microm) and 4-hydroxytamoxifen-ERalpha-mediated gene expression. Chromatin immunoprecipitation showed TPBM reduced E(2).ERalpha recruitment to an endogenous estrogen-responsive gene. TPBM inhibited E(2)-dependent growth of ERalpha-positive cancer cells (IC(50) of 5 microm). TPBM is not toxic to cells and does not affect estrogen-independent cell growth. TPBM acts outside of the ER ligand binding pocket, does not act by chelating the zinc in ER zinc fingers, and differs from known ERalpha inhibitors. Using a simple high throughput screen for inhibitors of ERalpha binding to the cERE, a small molecule inhibitor has been identified that selectively inhibits ERalpha-mediated gene expression and estrogen-dependent growth of cancer cells.