Arginase-1 in Plasma-Derived Exosomes as Marker of Metastasis in Patients with Head and Neck Squamous Cell Carcinoma

Immunoregulatory Arginase-1 (Arg-1) is present in the tumor microenvironment of solid tumors. Its association to clinicopathology and its prognostic impact are inconsistent among different tumor types and biological fluids. This study evaluated Arg-1 protein levels in tumors and the circulation of patients with head and neck squamous cell carcinoma (HNSCC) in relation to clinical stage and prognosis. Tumor Arg-1 expression was monitored via immunohistochemistry while plasma Arg-1 levels via ELISA in 37 HNSCC patients. Arg-1 presence in plasma-derived exosomes was assessed using Western blots in 20 HNSCC patients. High tumor Arg-1 expression correlated with favorable clinicopathology and longer recurrence-free survival (RFS), while high plasma Arg-1 levels were associated with unfavorable clinicopathology. All patients with low tumor and high plasma Arg-1 had nodal metastases and developed recurrence. This discrepancy was attributed to the presence of Arg-1-carrying exosomes. Arg-1 was found in plasma-derived exosomes from all HNSCC patients. High exosomal Arg-1 levels were associated with positive lymph nodes and short RFS. Circulating Arg-1+ exosomes represent a mechanism of active Arg-1 export from the tumor to the periphery. Exosomes reflected biologically relevant Arg-1 levels in metastatic HNSCC and emerged as potentially more accurate biomarkers of metastatic disease and RFS than tissue or plasma Arg-1 levels.

Breast Cancer Cell-Derived Adenosine Enhances Generation and Suppressor Function of Human Adaptive Regulatory T Cells

Introduction: Adaptive regulatory T cells (Tr1) are induced in the periphery by environmental stimuli. CD73 expression and adenosine (ADO) production by tumor cells may influence Tr1 generation and their immunosuppressive activity. Material and Methods: Tr1 were generated in co-cultures of CD4+CD25neg T cells, autologous immature dendritic cells (iDC), and irradiated ADO-producing CD73+ or non-producing CD73neg breast cancer (BrCa) cell lines (TU). The expression of ectonucleotidases and other surface markers on Tr1 was determined by flow cytometry. Tr1-mediated suppression of proliferation was evaluated in CFSE-based assays. Luciferase-based ATP detection assays and mass spectrometry were used to measure ATP hydrolysis and ADO levels. Cytokine levels were measured by ELISA or Luminex. CD73 expression on tumor cells or T cells in TU tissues was assessed by immunofluorescence. Results: CD73+ TU induced higher numbers of Tr1 cells (p < 0.01) than CD73neg TU. Tr1TU73+ hydrolyzed more exogenous ATP, produced more ADO, and mediated higher suppression than Tr1TU73neg (p < 0.05 for all). ARL67156, an ectonucleotidase inhibitor, and ZM241385, A2A receptor antagonist, reduced suppression of proliferation mediated by Tr1TU73+ cells (p < 0.01). Basal-like primary BrCa cells expressed higher levels of ectonucleotidases and induced more Tr1 than less aggressive primary luminal-like BrCa. Conclusion: BrCa producing ADO (CD73+ TU) favor the induction of Tr1, which expresses CD39 and CD73, hydrolyzes ATP to ADO, and effectively suppresses anti-tumor immunity.

Tympanometric evaluation of Eustachian tube function in Polish scuba divers

BACKGROUND

Scuba divers are subjected to relatively high ambient pressures while descending. Equalizing maneuvers (e.g., Valsalva) are necessary to open the Eustachian tube (ET) and allow air into the middle ear (ME) cavity. Insufficient opening of the ET leads to ME barotrauma, which is the most common injury related to scuba diving. The study aims were to assess the incidence of ME barotrauma and to compare tympanometric parameters and stapedial reflexes in scuba divers and non-diving individuals.

MATERIAL AND METHODS:

60 scuba divers participated in the study; control consisted of 90 non-diving volunteers without a history of otolaryngologic problems. All participants were examined with the use of otoscopy and tympanometry with evaluation of ipsilateral stapedial reflexes. The group studied was surveyed regarding occurrence of ME barotrauma and diving competence.

RESULTS

51.7% of the divers experienced ME barotrauma, the most common symptoms being earache and hearing loss. Comparison of the group studied and control revealed significantly lower ME pressure and compliance in scuba divers. In scuba divers with ME barotrauma, longer time from injury correlates directly with greater ME pressure and compliance, indicating tissue recovery. At 4,000Hz 100dB percentage of present stapedial reflexes among scuba divers was significantly lower than in controls; moreover, a greater number of dives correlated inversely with percentage of present stapedial reflexes at 4000Hz 100dB. The reduced thresholds at high intensities suggest a negative effect of scuba diving on hearing.

CONCLUSIONS

ME pressure and compliance, however still within the norm, are significantly lower in scuba divers than in non-diving healthy volunteers. This may be attributed to a subclinical form of barotrauma.

Microvessel density in head and neck squamous cell carcinoma

Purpose

Microvessel density (MVD) corresponds to the intensity of neo-angiogenesis. MVD assessments are based on the expression levels of the vascular endothelium markers such as, e.g., CD34 or CD105. The goal of this study was to assess MVD among patients with head and neck squamous cell carcinoma (HNSCC), and to evaluate the predictive value of MVD in head and neck cancers.

Methods

The study included 49 patients treated for HNSCC and 11 patients with dysplasia of the upper respiratory tract epithelium. Control tissues consisted of 12 normal mucous membranes of the throat. Expression levels of MVD markers were assessed by immunohistochemistry (IHC) using tissue microarrays (TMA). Clinicopathological factors and patients’ survival over the 5-year follow-up period were analyzed.

Results

The MVD/CD34 values were found to be significantly elevated in the HNSCCs compared to the non-malignant control tissues (p = 0.001) and to dysplastic tissues. (p = 0.02). Significantly higher MVD/CD105 values were also seen in the tumor compared to the control tissues (p = 0.001) or the dysplastic tissues (p = 0.001). Unexpectedly, significantly lower MVD/CD34 values were seen in the tumor tissues of patients with the T3–T4 tumors compared to those with T1–T2 tumors (p = 0.01).

Conclusions

HNSCCs have statistically higher MVD values compared to dysplasia of the upper respiratory tract epithelium. However, the MVD/CD34 values did not correlate with local invasiveness (the T feature) of HNSCCs. This counterintuitive observation suggests that assessments of MVD as performed on TMA by IHC using anti-CD34 or anti-CD105 antibodies considered to be specific for endothelial cell markers might underestimate the extent of the tumor vascularity in HNSCC.

Expression of the receptor for advanced glycation end products, a target for high mobility group box 1 protein, and its role in chronic recalcitrant rhinosinusitis with nasal polyps

A receptor for advanced glycation end products (RAGE) and its ligand high mobility group box 1 (HMGB1) protein has been linked to several chronic diseases, and acts as a trigger for inflammation signaling. Here, we study RAGE and HMGB1 expression in chronic, recalcitrant rhinosinusitis with nasal polyps (CRSwNP) to determine its potential clinical significance, i.e., disease recurrence and severity. RAGE and HMGB1 expression in CRSwNP was evaluated by immunohistochemistry in epithelial cells of fresh sinonasal mucosa samples obtained from the patients diagnosed with recalcitrant CRSwNP (n = 25) and normal control mucosa (NC) (n = 26). RAGE and HMGB1 expression levels in tissues were correlated with disease severity assessed by nasal endoscopy, CT scan, number of previous sinus surgeries, allergy status and nasosinusal microbiology. RAGE and HMGB1 were moderately or strongly expressed in CRSwNP tissue. No or weak RAGE expression was found in NC. HMGB1 was equally strongly expressed in NC. We observed a strong correlation between RAGE and disease severity, recurrence, undergone operations, asthma and aspirin exacerbated respiratory disease (AERD). Elevated RAGE expression is associated with increased disease severity, as well as allergy and AERD in patients with recalcitrant CRSwNP. It is possible that the explanation for recurrent CRSwNP pathogenesis might be related to RAGE overexpression with subsequent sinus mucosa hyperproliferation, necessitating several operations.

Antagonism of tumoral prolactin receptor promotes autophagy-related cell death

Therapeutic upregulation of macroautophagy in cancer cells provides an alternative mechanism for cell death. Prolactin (PRL) and its receptor (PRLR) are considered attractive therapeutic targets because of their roles as growth factors in tumor growth and progression. We utilized G129R, an antagonist peptide of PRL, to block activity of the tumoral PRL/PRLR axis, which resulted in inhibition of tumor growth in orthotopic models of human ovarian cancer. Prolonged treatment with G129R induced the accumulation of redundant autolysosomes in 3D cancer spheroids, leading to a type II programmed cell death. This inducible autophagy was a noncanonical beclin-1-independent pathway and was sustained by an astrocytic phosphoprotein (PEA-15) and protein kinase C zeta interactome. Lower levels of tumoral PRL/PRLR in clinical samples were associated with longer patient survival. Our findings provide an understanding of the mechanisms of tumor growth inhibition through targeting PRL/PRLR and may have clinical implications.

Cancer stem cells in head and neck squamous cell carcinoma

Recent studies have demonstrated that cancer stem cells (CSC) play an important role in the pathobiology of head and neck squamous cell carcinomas (HNSCC). This subpopulation of undifferentiated, self-renewing cells is responsible for resistance to conventional anti-cancer therapy, cancer recurrence, metastasis and ability to form a heterogeneous tumor. CSC are identified on the basis of specific markers, including membrane proteins or cell enzymes, or by using their self-renewal properties. As their resistance to standard HNSCC treatment may eventually lead to the lack of treatment success, there is an urgent need to better understanding CSC biology and identify them as potential target new treatment modality.

The immune signature of CD8(+)CCR7(+) T cells in the peripheral circulation associates with disease recurrence in patients with HNSCC

PURPOSE

Patients with cancer have an increased frequency of circulating apoptosis-sensitive CD8(+)CCR7(neg) T cells and few CD8(+)CCR7(+) T cells versus normal controls. The functional and clinical significance of this imbalance was investigated using peripheral blood of patients with squamous cell carcinoma of the head and neck (HNSCC).

EXPERIMENTAL DESIGN

The frequency of circulating CD8(+) T cells co-expressing CCR7, CD45RO, CD28, and Annexin V (ANXV) was evaluated in 67 patients and 57 normal controls by flow cytometry. Spearman rank correlations among immunophenotypic profiles were analyzed. Recursive partitioning classified subjects as patients or normal controls based on CD8(+)CCR7(+) T-cell percentages. Kaplan-Meier plots estimated disease-free survival (DFS).

RESULTS

The CD8(+)CCR7(+) T-cell frequency was low, whereas that of total CD8(+)CCR7(neg) and ANXV-binding CD8(+)CCR7(neg) T cells was higher in patients with HNSCC than in normal controls (P < 0.001-0.0001). ANXV binding correlated with the absence of CCR7 on CD8(+) T cells (P < 0.001). ANXV binding was negatively correlated with the CD8(+)CD45RO(neg)CCR7(+) (T(N)) cell frequency (P < 0.01) but positively correlated (P < 0.01) with that of CD8(+)CD45RO(+)CCR7(+) (T(CM)) T cells and of the two CCR7(neg) subsets (T(PM) and T(TD)). In recursive partitioning models, the CD8(+)CCR7(+) T-cell frequency of 31% distinguished patients from normal controls with 77% to 88% accuracy after cross-validation. In 25 patients tested before any therapy, the CD8(+)CCR7(+) T-cell frequency of less than 28% predicted disease recurrence within 4 years of definitive therapy (P < 0.0115).

CONCLUSION

The CD8(+)CCR7(+) T-cell frequency in HNSCC patients' blood tested at diagnosis can discriminate them from normal controls and predicts disease recurrence.

PRAME expression in head and neck cancer correlates with markers of poor prognosis and might help in selecting candidates for retinoid chemoprevention in pre-malignant lesions

OBJECTIVES

PRAME (Preferentially Expressed Antigen in Melanoma) is a tumor-associated antigen recognized by immunocytes, and it induces cytotoxic T cell-mediated responses in melanoma. PRAME expression in tumors interferes with retinoic acid receptor (RAR) signaling thus promoting tumor progression. Here, we study PRAME expression in head and neck squamous cell carcinoma (HNSCC) to determine its potential clinical significance.

MATERIALS AND METHODS

PRAME expression in HNSCC was evaluated by immunohistochemistry in tissue microarrays of primary tumors (n=53), metastatic lymph nodes (n=8) and normal oral mucosa (n=11). Biopsies of dysplastic oral lesions (n=12) were also examined. PRAME expression levels in tissues were correlated with markers of poor prognosis in HNSCC. PRAME mRNA in HNSCC cell lines and in normal immortalized human keratinocytes (HaCaT cell line) was measured by qRT-PCR, and the protein expression by flow cytometry and western blots.

RESULTS

PRAME was expressed in HNSCC cell lines and HNSCC lesions. PRAME expression in dysplastic mucosa was variable. No or only weak expression was found in normal cells or tissues. PRAME expression levels significantly correlated with the tumor grade, size, nodal involvement and the clinical status of HNSCC patients.

CONCLUSIONS

Elevated PRAME expression associates with clinicopathologic markers of poor outcome in HNSCC and might identify potential candidates with pre-cancerous lesions for chemoprevention with retinoids.

17β Hydroxysteroid dehydrogenase type 12 (HSD17B12) is a marker of poor prognosis in ovarian carcinoma

OBJECTIVE

17β-hydroxysteroid dehydrogenase isoform 12 (HSD17B12) overexpression is associated with poor clinical outcome in invasive ductal carcinoma of the breast. Here, we evaluated HSD17B12 overexpression and its activity in ovarian carcinoma (OvCa) to determine its role in the growth and progression of this tumor.

METHODS

Immunohistochemical analysis of HSD17B12 expression was performed in 100 tissue samples of untreated OvCa and was correlated with clinicopathologic characteristics and patient outcome. In A2780 OvCa cell line expressing HSD17B12, siRNA knockdown of the enzyme was performed, and its effects on tumor cell growth and Annexin V binding were determined.

RESULTS

HSD17B12 expression was detected in all tumor samples, but the staining intensity was variable. Normal ovarian epithelium was negative. Patients with tumor showing weak/moderate expression of HSD17B12 had a better overall survival than those with strongly positive tumors (p<0.001). The time to first recurrence was longer for patients with tumors with heterogeneous staining relative to patients with tumors that were uniformly positive (p<0.001). Upon silencing of HSD17B12 in tumor cells, their growth was inhibited (p<0.005) and apoptosis was increased (p<0.05). Arachidonic acid but not estradiol reversed the growth inhibition mediated by HSD17B12 knockdown.

CONCLUSION

HSD17B12 overexpression is shown to be a marker of poor survival in patients with OvCa. Expression in the tumor and function of this enzyme facilitates OvCa progression.

Targeting ALDH(bright) human carcinoma-initiating cells with ALDH1A1-specific CD8⁺ T cells

PURPOSE

Cancer-initiating cells (CIC) are considered to represent the subpopulation of tumor cells that is resistant to conventional cancer treatments, highly tumorigenic in immunodeficient mice, and responsible for tumor recurrence and metastasis. Based on an elevated aldehyde dehydrogenase (ALDH) activity attributable to ALDH1/3 isoforms, ALDH(bright) cells have been identified and isolated from tumors and shown to have characteristics of CIC. The ALDH1A1 isoform was previously identified as a tumor antigen recognized by CD8(+) T cells. This study examines the ability of ALDH1A1-specific CD8(+) T cells to eliminate ALDH(bright) cells and control tumor growth and metastases.

EXPERIMENTAL DESIGN

ALDH(bright) cells were isolated by flow cytometry using ALDEFLUOR from HLA-A2(+) human head and neck, breast, and pancreas carcinoma cell lines and tested for their tumorigenicity in immunodeficient mice. ALDH1A1-specific CD8(+) T cells were generated in vitro and tested for their ability to eliminate CICs in vitro and in vivo by adoptive transfer to immunodeficient mice bearing human tumor xenografts.

RESULTS

ALDH(bright) cells isolated by flow cytometry from HLA-A2(+) breast, head and neck, and pancreas carcinoma cell lines at low numbers (500 cells) were tumorigenic in immunodeficient mice. ALDH(bright) cells present in these cell lines, xenografts, or surgically removed lesions were recognized by ALDH1A1-specific CD8(+) T cells in vitro. Adoptive therapy with ALDH1A1-specific CD8(+) T cells eliminated ALDH(bright) cells, inhibited tumor growth and metastases, or prolonged survival of xenograft-bearing immunodeficient mice.

CONCLUSIONS

The results of this translational study strongly support the potential of ALDH1A1-based immunotherapy to selectively target CICs in human cancer.

Blast-derived microvesicles in sera from patients with acute myeloid leukemia suppress natural killer cell function via membrane-associated transforming growth factor-beta1

BACKGROUND

Natural killer cell cytotoxicity is decreased in patients with acute myeloid leukemia in comparison to that in normal controls. Tumor-derived microvesicles present in patients' sera exert detrimental effects on immune cells and may influence tumor progression.

DESIGN AND METHODS

We investigated the microvesicle protein level, molecular profile and suppression of natural killer cell activity in patients with newly diagnosed acute myeloid leukemia.

RESULTS

The patients' sera contained higher levels of microvesicles compared to the levels in controls (P<0.001). Isolated microvesicles had a distinct molecular profile: in addition to conventional microvesicle markers, they contained membrane-associated transforming growth factor-β1, MICA/MICB and myeloid blasts markers, CD34, CD33 and CD117. These microvesicles decreased natural killer cell cytotoxicity (P<0.002) and down-regulated expression of NKG2D in normal natural killer cells (P<0.001). Sera from patients with acute myeloid leukemia contained elevated levels of transforming growth factor-β, and urea-mediated dissociation of microvesicles further increased the levels of this protein. Neutralizing anti-transforming growth factor-β1 antibodies inhibited microvesicle-mediated suppression of natural killer cell activity and NKG2D down-regulation. Interleukin-15 protected natural killer cells from adverse effects of tumor-derived microvesicles.

CONCLUSIONS

We provide evidence for the existence in acute myeloid leukemia of a novel mechanism of natural killer cell suppression mediated by tumor-derived microvesicles and for the ability of interleukin-15 to counteract this suppression.

Identification of Hydroxysteroid (17β) dehydrogenase type 12 (HSD17B12) as a CD8+ T-cell-defined human tumor antigen of human carcinomas

Hydroxysteroid (17β) dehydrogenase type 12 (HSD17B12) is a multifunctional isoenzyme functional in the conversion of estrone to estradiol (E2), and elongation of long-chain fatty acids, in particular the conversion of palmitic to archadonic (AA) acid, the precursor of sterols and the inflammatory mediator, prostaglandin E(2). Its overexpression together with that of COX-2 in breast carcinoma is associated with a poor prognosis. We have identified the HSD17B12(114-122) peptide (IYDKIKTGL) as a naturally presented HLA-A*0201 (HLA-A2)-restricted CD8(+) T-cell-defined epitope. The HSD17B12(114-122) peptide, however, is poorly immunogenic in its in vitro ability to induce peptide-specific CD8(+) T cells. Acting as an "optimized peptide", a peptide (TYDKIKTGL), which is identical to the HSD17B12(114-122) peptide except for threonine at residue 1, was required for inducing in vitro the expansion of CD8(+) T-cell effectors cross-reactive against the HSD17B12(114-122) peptide. In IFN-γ ELISPOT assays, these effector cells recognize HSD17B12(114-122) peptide-pulsed target cells, as well as HLA-A2(+) squamous cell carcinoma of the head and neck (SCCHN) and breast carcinoma cell lines overexpressing HSD17B12 and naturally presenting the epitope. Whereas growth inhibition of a breast carcinoma cell line induced by HSD17B12 knockdown was only reversed by AA, in a similar manner, the growth inhibition of the SCCHN PCI-13 cell line by HSD17B12 knockdown was reversed by E2 and AA. Our findings provide the basis for future studies aimed at developing cancer vaccines for targeting HSD17B12, which apparently can be functional in critical metabolic pathways involved in inflammation and cancer.

Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic

OBJECTIVES

IRX-2 is a novel immunotherapeutic containing physiologic quantities of several cytokines which protects human T lymphocytes from tumor-induced or drug-induced apoptosis. Here, we investigate the mechanisms responsible for IRX-2-mediated protection of T lymphocytes exposed to tumor-derived microvesicles (TMV).

METHODS

Jurkat cells or primary human T cells ± IRX-2 were co-incubated with TMV and then examined by flow cytometry or Western blots for expression of molecules regulating cell survival (FLIP, Bcl-2, Bcl-xL, Mcl-1) or death (Fas, caspase 8, caspase 9, Bax, Bid). ANX V binding, caspase activation or cytochrome c release were also measured ± cycloheximide (CHX) or ± the Akt-specific inhibitor. Jurkat cells transfected with the cFLIP gene were used to evaluate the role of cFLIP in IRX-2-mediated protection. Effects of CHX on IRX-2-mediated protection and activation of NF-κB upon the TMV/IRX-2 treatment were also measured.

RESULTS

IRX-2 protected T cells from apoptosis by preventing Fas overexpression induced by TMV and blocking caspase 8 activation by up-regulating cFLIP. Jurkat cells overexpressing cFLIP were more resistant to TMV-induced apoptosis than the mock-transfected cells (p < 0.02). Signaling via the PI3K/Akt pathway, IRX-2 corrected the imbalance of pro- versus anti-apoptotic proteins induced by TMV and promoted NF-κB translocation to the nucleus. CHX abolished IRX-2-mediated protection in T cells, suggesting that IRX-2 induces de novo synthesis of one or more proteins that are required for protection.

CONCLUSIONS

This biologic may be therapeutically useful for protection of activated T cells from tumor-induced immune suppression and death.

Adenosine and prostaglandin E2 cooperate in the suppression of immune responses mediated by adaptive regulatory T cells

Adaptive regulatory T cells (Tr1) are induced in the periphery upon encountering cognate antigens. In cancer, their frequency is increased; however, Tr1-mediated suppression mechanisms are not yet defined. Here, we evaluate the simultaneous involvement of ectonucleotidases (CD39/CD73) and cyclooxygenase 2 (COX-2) in Tr1-mediated suppression. Human Tr1 cells were generated from peripheral blood mononuclear cell-derived, sorted CD4(+)CD25(-) T cells and incubated with autologous immature dendritic cells, irradiated COX-2(+) or COX-2(-) tumor cells, and IL-2, IL-10, and IL-15 (each at 10-15 IU/ml) for 10 days as described (Bergmann, C., Strauss, L., Zeidler, R., Lang, S., and Whiteside, T. L. (2007) Cancer Immunol. Immunother. 56, 1429-1442). Tr1 were phenotyped by multicolor flow cytometry, and suppression of proliferating responder cells was assessed in carboxyfluorescein diacetate succinimidyl ester-based assays. ATP hydrolysis was measured using a luciferase detection assay, and levels of adenosine or prostaglandin E(2) (PGE(2)) in cell supernatants were analyzed by mass spectrometry or ELISA, respectively. Intracellular cAMP levels were measured by enzyme immunoassay. The COX-2(+) tumor induced a greater number of Tr1 than COX-2(-) tumor (p < 0.05). Tr1 induced by COX-2(+) tumor were more suppressive, hydrolyzed more exogenous ATP (p < 0.05), and produced higher levels of adenosine and PGE(2) (p < 0.05) than Tr1 induced by COX-2(-) tumor. Inhibitors of ectonucleotidase activity, A(2A) and EP(2) receptor antagonists, or an inhibitor of the PKA type I decreased Tr1-mediated suppression (p < 0.05), whereas rolipram, a PDE(4) inhibitor, increased the intracellular cAMP level in responder cells and their susceptibility to Tr1-mediated suppression. Tr1 present in tumors or the peripheral blood of head and neck squamous cell carcinoma patients co-expressed COX-2, CD39, and CD73. A concomitant inhibition of PGE(2) and adenosine via the common intracellular cAMP pathway might be a novel approach for improving results of immune therapies for cancer.

Abstract 5605: Targeting cancer stem cells in squamous cell carcinoma of the head and neck with combinatorial adoptive immunotherapy

According to current views, in order for cancer immunotherapy to be successful it must target cancer stem cells (CSC) and counteract the multiple mechanisms involved in immune escape. Guided by these concepts, we have developed a combinatorial adoptive immunotherapeutic strategy which utilizes a monoclonal antibody (mAb) and cytotoxic T lymphocytes (CTL) in combination with continuous administration of low dose cyclophosphamide (metronomic chemotherapy) to target CSC and differentiated tumor cells, as well as activated pericytes in the tumor microenvironment. The targets selected are aldehyde dehydrogenase 1 family member A1 (ALDH1A1) and chondroitin sulfate proteoglycan 4 (CSPG4). We now report that ALDHbright cells in squamous cell carcinoma of the head and neck (SCCHN) cell lines, which express high levels of ALDH1A1, are tumorigenic at low inoculum in immunodeficient mice, and particularly sensitive to recognition by ALDH1A1-specific T cells. The ALDHbright cells express CSPG4, a cell surface antigen functional in adhesion and migration. CSPG4 is also expressed on tumor associated activated pericytes which stabilize tumor blood vessels and provide vascular endothelial cells with survival signals. Administration of CSPG4-specific mAb and metronomic chemotherapy combined with intralesional adoptive transfer of ALDH1A1 peptide-specific CTL to mice bearing human SCCHN PCI-13-derived xenografts significantly reduced tumor growth and number of tumor cells with CSC phenotype. The antitumor effects of the immunotherapy we have developed were significantly higher than those of its individual components. These results argue in favor of the possibility that this combinatorial strategy may enhance the clinical efficacy of adoptive immunotherapy in SCCHN patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5605.

TLR4 signaling induced by lipopolysaccharide or paclitaxel regulates tumor survival and chemoresistance in ovarian cancer

Toll-like receptors (TLRs) expressed on immune cells trigger inflammatory responses. TLRs are also expressed on ovarian cancer (OvCa) cells, but the consequences of signaling by the TLR4/MyD88 pathway in these cells are unclear. Here, TLR4 and MyD88 expression in OvCa tissues (n=20) and cell lines (OVCAR3, SKOV3, AD10, A2780 and CP70) was evaluated by reverse transcriptase-PCR, western blots and immunohistochemistry. Cell growth, apoptosis, nuclear factor-kappaB (NF-kappaB) translocation, IRAK4 and TRIF expression and cJun phosphorylation were measured following tumor cell exposure to the TLR4 ligands, lipopolysaccharide (LPS) or paclitaxel (PTX). Culture supernatants were tested for cytokine levels. TLR4 was expressed in all tumors, tumor cell lines and normal epithelium. MyD88 was detectable in tumor tissues and in 3/5 OvCa lines but not in normal cells. In MyD88(+) SCOV3 cells, LPS or PTX binding to TLR4 induced IRAK4 activation and cJun phosphorylation, activated the NF-kappaB pathway and promoted interleukin (IL)-8, IL-6, vascular endothelial growth factor and monocyte chemotactic protein-1 production and resistance to drug-induced apoptosis. Silencing of TLR4 in SCOV3 cells with small interference RNA resulted in phosphorylated-cJun (p-cJun) downregulation and a loss of PTX resistance. In PTX-sensitive, MyD88(neg) A2780 cells, TLR4 stimulation upregulated TRIF, and TLR4 silencing eliminated this effect. Thus, TLR4/MyD88 signaling supports OvCa progression and chemoresistance, promoting immune escape.

Generation and accumulation of immunosuppressive adenosine by human CD4+CD25highFOXP3+ regulatory T cells

Naturally occurring regulatory T cells (nTreg) are crucial for maintaining tolerance to self and thus preventing autoimmune diseases and allograft rejections. In cancer, Treg down-regulate antitumor responses by several distinct mechanisms. This study analyzes the role the adenosinergic pathway plays in suppressive activities of human nTreg. Human CD4(+)CD25(high)FOXP3(+) Treg overexpress CD39 and CD73, ectonucleotidases sequentially converting ATP into AMP and adenosine, which then binds to A(2a) receptors on effector T cells, suppressing their functions. CD4(+)CD39(+) and CD4(+)CD25(high) T cells express low levels of adenosine deaminase (ADA), the enzyme responsible for adenosine breakdown, and of CD26, a surface-bound glycoprotein associated with ADA. In contrast, T effector cells are enriched in CD26/ADA but express low levels of CD39 and CD73. Inhibitors of ectonucleotidase activity (e.g. ARL67156) and antagonists of the A(2a) receptor (e.g. ZM241385) blocked Treg-mediated immunosuppression. The inhibition of ADA activity on effector T cells enhanced Treg-mediated immunosuppression. Thus, human nTreg characterized by the presence of CD39 and the low expression of CD26/ADA are responsible for the generation of adenosine, which plays a major role in Treg-mediated immunosuppression. The data suggest that the adenosinergic pathway represents a potential therapeutic target for regulation of immunosuppression in a broad variety of human diseases.

Sheddase activity of tumor necrosis factor-alpha converting enzyme is increased and prognostically valuable in head and neck cancer

Tumor necrosis factor alpha converting enzyme (TACE) is a sheddase overexpressed in cancers that generates cancer cell growth and survival factors, and is implicated in carcinogenesis and tumor growth. This indicates that TACE could be a potentially important cancer biomarker. Unexpectedly, TACE expression in cancer tissues does not correlate with cancer stage or invasiveness. Although TACE sheddase activity is a more direct and potentially better indicator of TACE biology and might be a better cancer biomarker than TACE expression, it has not been studied in cancer tissues. In the present study, we developed a reliable specific assay for quantification of TACE sheddase activity, investigated TACE activity and TACE protein expression in head and neck cancer (HNC) tissues, and examined the correlation of the results with HNC clinical stages and likelihood to recur. We found that HNC cell lines and tissues contained remarkably higher quantities of TACE activity and TACE protein than normal keratinocytes or oral mucosa. siRNA silencing of TACE resulted in the inhibition of release of the tumorogenic factors amphiregulin and transforming growth factor alpha, and tumor protective factors tumor necrosis factor receptors from HNC cells. Importantly, TACE activity, but not TACE protein expression, was significantly higher in large, T3/T4, primary tumors relative to small, T1/T2, primary tumors, and especially in primary tumors likely to recur relative to those unlikely to recur. These data show that increased TACE activity in cancer is biologically and clinically relevant, and indicate that TACE activity could be a significant biomarker of cancer prognosis.

Increased ectonucleotidase expression and activity in regulatory T cells of patients with head and neck cancer

PURPOSE

Regulatory T cell (Treg) frequency and activity are increased in cancer patients and play a major role in tumor escape. Although disease progression is favored by the presence of Treg, mechanisms used by Treg to suppress antitumor immunity are unknown. The ectonucleotidases CD39 and CD73 are expressed in Treg and convert ATP into immunosuppressive adenosine. In this study, the involvement of the adenosinergic pathway in Treg-mediated suppression in head and neck squamous cell carcinoma (HNSCC) patients was evaluated.

EXPERIMENTAL DESIGN

HNSCC patients with an active disease (n = 19) and patients with no evident disease after therapy (n = 14) were studied. Ectonucleotidase expression on CD4(+) T cells and CD4(+)CD25(high) Treg was evaluated by flow cytometry and compared with normal controls. Ectonucleotidase activity was also compared within these three groups. The data were analyzed for associations of ectonucleotidase expression/function with disease stage.

RESULTS

The percentages and expression levels of CD39 and CD73 in CD4(+) T cells and Treg were greater in HNSCC than in normal controls and highest in patients with no evident disease. Patients' Treg hydrolyzed ATP at higher rates and produced higher levels of adenosine than normal controls' Treg. The increased frequency and enzymatic activity of CD4(+)CD39(+) cells corresponded to increased adenosine-mediated suppression of effector T cells, which was partly inhibited by ARL67156, an ectonucleotidase inhibitor, and by ZM241385, a selective A(2a)/A(2b) receptor antagonist.

CONCLUSIONS

CD39(+) Treg frequency and adenosine-mediated suppression are significantly increased in HNSCC patients. The adenosinergic pathway is involved in Treg-mediated immunosuppression in cancer and its attenuation could be a promising immunotherapeutic strategy for patients with HNSCC.

Tumor-derived microvesicles promote regulatory T cell expansion and induce apoptosis in tumor-reactive activated CD8+ T lymphocytes

Sera of patients with cancer contain membraneous microvesicles (MV) able to induce apoptosis of activated T cells by activating the Fas/Fas ligand pathway. However, the cellular origin of MV found in cancer patients' sera varies as do their molecular and cellular profiles. To distinguish tumor-derived MV in cancer patients' sera, we used MAGE 3/6(+) present in tumors and MV. Molecular profiles of MAGE 3/6(+) MV were compared in Western blots or by flow cytometry with those of MV secreted by dendritic cells or activated T cells. These profiles were found to be distinct for each cell type. Only tumor-derived MV were MAGE 3/6(+) and were variably enriched in 42-kDa Fas ligand and MHC class I but not class II molecules. Effects of MV on signaling via the TCR and IL-2R and proliferation or apoptosis of activated primary T cells and T cell subsets were also assessed. Functions of activated CD8(+) and CD4(+) T lymphocytes were differentially modulated by tumor-derived MV. These MV inhibited signaling and proliferation of activated CD8(+) but not CD4(+) T cells and induced apoptosis of CD8(+) T cells, including tumor-reactive, tetramer(+)CD8(+) T cells as detected by flow cytometry for caspase activation and annexin V binding or by DNA fragmentation. Tumor-derived but not dendritic cell-derived MV induced the in vitro expansion of CD4(+)CD25(+)FOXP3(+) T regulatory cells and enhanced their suppressor activity. The data suggest that tumor-derived MV induce immune suppression by promoting T regulatory cell expansion and the demise of antitumor CD8(+) effector T cells, thus contributing to tumor escape.

Interleukin-15 enhances natural killer cell cytotoxicity in patients with acute myeloid leukemia by upregulating the activating NK cell receptors

Interleukin-15 (IL-15) has a major role in NK-cell homeostasis. Modulation of the relative frequency and expression intensity of the NK-cell receptors by IL-15 may increase NK cell-mediated cytotoxicity in cancer patients. We investigated the receptor repertoire and measured NK-cell activity in newly diagnosed AML patients and evaluated the ex vivo effects of IL-15. The expression of the activating NK cell receptors was significantly decreased in the AML patients compared to that in NK cells of healthy donors. When NK cells obtained from AML patients were cultured with IL-15, expression of the activating receptors was significantly upregulated compared to pre-culture levels. Concomitantly, cytotoxic activity of NK cells against autologous leukemic blasts increased following IL-15 stimulation. This IL-15 induced increase in activity was blocked by neutralizing antibodies specific for the NK cell activating receptors. These pre-clinical data support the future use of IL-15 for NK cell- based therapies for AML patients.

Biological significance of prolactin in gynecologic cancers

There is increasing evidence that prolactin (PRL), a hormone/cytokine, plays a role in breast, prostate, and colorectal cancers via local production or accumulation. Elevated levels of serum PRL in ovarian and endometrial cancers have been reported, indicating a potential role for PRL in endometrial and ovarian carcinogenesis. In this study, we show that serum PRL levels are significantly elevated in women with a strong family history of ovarian cancer. We show dramatically increased expression of PRL receptor in ovarian and endometrial tumors as well as in endometrial hyperplasia, signifying the importance of PRL signaling in malignant and premalignant conditions. PRL mRNA was expressed in ovarian and endometrial tumors, indicating the presence of an autocrine loop. PRL potently induced proliferation in several ovarian and endometrial cancer cell lines. Binding of PRL to its receptor was followed by rapid phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, mitogen-activated protein kinase/ERK kinase 1, signal transducer and activator of transcription 3, CREB, ATF-2, and p53 and activation of 37 transcription factors in ovarian and endometrial carcinoma cells. PRL also activated Ras oncogene in these cells. When human immortalized normal ovarian epithelial cells were chronically exposed to PRL, a malignant transformation occurred manifested by the acquired ability of transformed cells to form clones, grow in soft agar, and form tumors in severe combined immunodeficient-beige mice. Transformation efficiency was diminished by a Ras inhibitor, providing proof that PRL-induced transformation uses the Ras pathway. In summary, we present findings that indicate an important role for PRL in ovarian and endometrial tumorigenesis. PRL may represent a risk factor for ovarian and endometrial cancers.

Increased frequency and suppression by regulatory T cells in patients with acute myelogenous leukemia

PURPOSE

Regulatory CD4(+)CD25(high)Foxp3(+) T cells (Treg) control peripheral immune tolerance. Patients with cancer, including those with hematologic malignancies, have elevated numbers of Treg in the peripheral circulation and in tumor tissues. However, mechanisms of suppression and clinical significance of Treg, especially in patients with acute myelogenous leukemia (AML), has not been well defined.

EXPERIMENTAL DESIGN

We prospectively evaluated the phenotype, function, and mechanisms of suppression used by Treg in newly diagnosed untreated AML patients. The relationship between the frequency of circulating Treg and the disease status as well as treatment outcome was also evaluated.

RESULTS

The percentage of circulating Treg was higher (P < 0.0001) and their phenotype was distinct in AML patients relative to normal controls. Suppression mediated by Treg coincubated with proliferating autologous responder cells was also higher (P < 0.001) in AML than that mediated by control Treg. Using Transwell inserts, we showed that interleukin-10 and transforming growth factor-beta1 production as well as cell-to-cell contact were necessary for Treg-mediated suppression. Also, the pretreatment Treg frequency predicted response to chemotherapy. Unexpectedly, patients who achieved complete remission still had elevated frequency of Treg, which mediated high levels of suppressor activity.

CONCLUSIONS

Treg accumulating in the peripheral circulation of AML patients mediate vigorous suppression via contact-dependent and contact-independent mechanisms. Patients with lower Treg frequency at diagnosis have a better response to induction chemotherapy. During the post-induction period, the Treg frequency and suppressive activity remain elevated in complete remission, suggesting that Treg are resistant to conventional chemotherapy.

Role of eotaxin-1 signaling in ovarian cancer

PURPOSE

Tumor cell growth and migration can be directly regulated by chemokines. In the present study, the association of CCL11 with ovarian cancer has been investigated.

EXPERIMENTAL DESIGN AND RESULTS

Circulating levels of CCL11 in sera of patients with ovarian cancer were significantly lower than those in healthy women or women with breast, lung, liver, pancreatic, or colon cancer. Cultured ovarian carcinoma cells absorbed soluble CCL11, indicating that absorption by tumor cells could be responsible for the observed reduction of serum level of CCL11 in ovarian cancer. Postoperative CCL11 levels in women with ovarian cancer negatively correlated with relapse-free survival. Ovarian tumors overexpressed three known cognate receptors of CCL11, CC chemokine receptors (CCR) 2, 3, and 5. Strong positive correlation was observed between expression of individual receptors and tumor grade. CCL11 potently stimulated proliferation and migration/invasion of ovarian carcinoma cell lines, and these effects were inhibited by neutralizing antibodies against CCR2, CCR3, and CCR5. The growth-stimulatory effects of CCL11 were likely associated with activation of extracellular signal-regulated kinase 1/2, MEK1, and STAT3 phosphoproteins and with increased production of multiple cytokines, growth factors, and angiogenic factors. Inhibition of CCL11 signaling by the combination of neutralizing antibodies against the ligand and its receptors significantly increased sensitivity to cisplatin in ovarian carcinoma cells.

CONCLUSION

We conclude that CCL11 signaling plays an important role in proliferation and invasion of ovarian carcinoma cells and CCL11 pathway could be targeted for therapy in ovarian cancer. Furthermore, CCL11 could be used as a biomarker and a prognostic factor of relapse-free survival in ovarian cancer.

Triggering of Toll-like receptor 4 expressed on human head and neck squamous cell carcinoma promotes tumor development and protects the tumor from immune attack

Toll-like receptors (TLR) expressed on inflammatory cells play a key role in host defense against pathogens, benefiting the host. TLR are also expressed on tumor cells. To evaluate the role of TLR in tumor cells, we investigated TLR4 signaling effects on human head and neck squamous cell carcinoma (HNSCC). Tumor tissues were obtained from 27 patients with laryngeal and 12 with oral cavity cancers. Normal mucosa was obtained from 10 patients with nonneoplastic disorders. Smears for bacteria were taken from all patients during surgery. TLR4 expression in tumors and HNSCC cell lines (PCI-1, PCI-13, and PCI-30) was detected by reverse transcription-PCR and immunohistochemistry. Cell growth, apoptosis, nuclear factor-kappaB (NF-kappaB) translocation, and MyD88 and IRAK-4 expression, as well as Akt phosphorylation were measured following tumor cell exposure to the TLR4 ligand lipopolysaccharide (LPS). Tumor cell sensitivity to NK-92-mediated lysis was evaluated in 4-hour (51)Cr-release assays. Cytokine levels in HNSCC supernatants were measured in Luminex-based assays. TLR4 was expressed in all tumors, HNSCC cell lines, and normal mucosa. The TLR4 expression intensity correlated with tumor grade. LPS binding to TLR4 on tumor cells enhanced proliferation, activated phosphatidylinositol 3-kinase/Akt pathway, up-regulated IRAK-4 expression, induced nuclear NF-kappaB translocation, and increased production (P<0.05) of interleukin (IL)-6, IL-8, vascular endothelial growth factor, and granulocyte macrophage colony-stimulating factor. TLR4 triggering protected tumor cells from lysis mediated by NK-92 cells. TLR4 ligation on tumor cells supports HNSCC progression.

T regulatory type 1 cells in squamous cell carcinoma of the head and neck: mechanisms of suppression and expansion in advanced disease

PURPOSE

Regulatory T cells play a major role in tumor escape from immunosurveillance. T regulatory cells type 1 (Tr1), a subset of regulatory T cells present in the tumor and peripheral circulation of patients with head and neck squamous cell carcinoma (HNSCC), mediate immune suppression and might contribute to tumor progression.

EXPERIMENTAL DESIGN

CD4+CD25-T cells were isolated from peripheral blood mononuclear cells (PBMC) or tumor-infiltrating lymphocytes (TIL) of 26 HNSCC patients and 10 normal controls. The Tr1 cell phenotype was determined before and after culture in the presence of interleukin (IL)-2, IL-10, and IL-15, each at 10 to 20 IU/mL. Suppression was measured in carboxyfluorescein diacetate succinimidyl ester-based proliferation assays with or without neutralizing anti-IL-10 or anti-transforming growth factor-beta1 (TGF-beta1) monoclonal antibodies in Transwell systems. ELISA was used to define the Tr1 cytokine profile.

RESULTS

Tr1 cells originate from CD4(+)CD25(-) precursors present in TIL and PBMC of HNSCC patients. Cytokine-driven ex vivo expansion of Tr1 precursors yielded CD4+CD25-Foxp3lowCD132+IL-10+TGF-beta1+ populations that mediated higher suppression than Tr1 cells of normal controls (P < 0.0001). Tr1 cells suppressed proliferation of autologous responders via IL-10 and TGF-beta1 secretion. Expression of these cytokines was higher in TIL-derived than PBMC-derived Tr1 cells (P < 0.0001). The Tr1 cell frequency and suppressor function were significantly higher in patients presenting with advanced than early disease stages and in patients "cured" by oncologic therapies than in those with active disease.

CONCLUSIONS

In HNSCC, Tr1 cell generation is promoted at the tumor site. Tr1 cells use TGF-beta and IL-10 to mediate suppression. They expand during disease progression and also following cancer therapy in patients with no evident disease.

Expression of ICOS on human melanoma-infiltrating CD4+CD25highFoxp3+ T regulatory cells: implications and impact on tumor-mediated immune suppression

OBJECTIVE

Interaction of ICOS with its ligand (ICOSL, B7-H2) promotes T cell responses. As CD4+CD25highFoxp3+ naturally occurring T regulatory cells in melanoma patients express ICOS, we investigated the impact of ICOS on naturally occurring T regulatory cell function.

METHODS

Expression of ICOS and T regulatory (Treg) cell markers was determined on CD4+CD25high T cells in PBMC and tumor-infiltrating lymphocytes from melanoma patients (n=10) and PBMC of normal controls (n=10) by multicolor flow cytometry. Suppression mediated by sorted ICOShigh and ICOSlow Treg was assessed in CFSE-based suppression assays with autologous CD4+CD25- responder cells (RC). Transwell inserts separating Treg from RC were used to evaluate suppression mechanisms used by Treg. ICOShigh or ICOSlow Treg were coincubated with RC+/-TCR and IL-2 stimulation. ICOShigh and ICOS- Treg were also expanded under conditions previously shown to induce Tr1 from RC.

RESULTS

Treg in tumor-infiltrating lymphocytes expressed ICOS (mean fluorescence intensity=70+/-10), while Treg in PBMC had low ICOS expression (mean fluorescence intensity=3.5+/-2.5, p<or=0.001). ICOShigh Treg up-regulated Treg markers (p<or=0.0016) and mediated stronger suppression (p<or=0.001) relative to ICOSlow Treg. ICOShigh Treg induced Tr1 cells in nonactivated RC and Th2 cells in preactivated RC. ICOShigh Treg exposed to Tr1 cytokines expressed IL-10 and suppressed RC (92+/-12%) in contrast to ICOSlow Treg, which mediated low suppression (21+/-15%; p<or=0.0028).

CONCLUSION

ICOShigh Treg can induce diverse immune responses in RC, depending on activation signals and cytokines present. ICOShigh Treg induce Tr1 or Th2 cells depending on the activation state of RC. In a "Tr1" cytokine milieu, ICOShigh Treg transit to Tr1.

Up-regulation of NK cell activating receptors following allogeneic hematopoietic stem cell transplantation under a lymphodepleting reduced intensity regimen is associated with elevated IL-15 levels

Because natural killer (NK) cells can be potent anti-tumor effectors after allogeneic stem cell transplantation, we investigated NK reconstitution and receptor expression in patients undergoing allogeneic hematopoietic stem cell transplantation, focusing on the activating receptors that trigger anti-tumor responses. We determined that NK levels in the peri-transplant period were inversely proportional to the dramatic rise and fall in plasma levels of the NK homeostatic cytokine IL-15, which increased more than 50-fold from pretreatment to the day of transplant during the lymphoreductive preparative regimen. Furthermore, in NK cells cultured with IL-15, we observed an up-regulation of the activating receptors NKG2D, NKp30, and NKp46, associated with an increase in anti-tumor lytic activity. Similarly, the expression of these activating receptors increased significantly during the early post-transplant period, concurrent with a rapid increase in total NK cells and a shift toward increased expression of CD56. These data suggest that the cytokine milieu of transplants, in particular elevated levels of IL-15, may contribute to anti-tumor efficacy post-transplant by enhancing the recovery of NK subsets and modulating expression of activating receptors.