Interferon‐γ down‐regulates NKG2D ligand expression and impairs the NKG2D‐mediated cytolysis of MHC class I‐deficient melanoma by natural killer cells

NKG2D operates as an activating receptor on natural killer (NK) cells and costimulates the effector function of αβ CD8⁺ T cells. Ligands of NKG2D, the MHC class I chain‐related (MIC) and UL16 binding protein (ULBP) molecules, are expressed on a variety of human tumors, including melanoma. Recent studies in mice demonstrated that NKG2D mediates tumor immune surveillance, suggesting that antitumor immunity in humans could be enhanced by therapeutic manipulation of NKG2D ligand (NKG2DL) expression. However, signals and mechanisms regulating NKG2DL expression still need to be elucidated. Here, we asked whether the proinflammatory cytokine Interferon‐γ (IFN‐γ) affects NKG2DL expression in melanoma. Cell lines, established from MHC class I‐negative and ‐positive melanoma metastases, predominantly expressed MICA and ULBP2 molecules on their surface. Upon IFN‐γ treatment, expression of MICA, in some cases, also of ULBP2 decreased. Besides melanoma, this observation was made also for glioma cells. Down‐regulation of NKG2DL surface expression was dependent on the cytokine dose and the duration of treatment, but was neither due to an intracellular retention of the molecules nor to an increased shedding of ligands from the tumor cell surface. Instead, quantitative RT‐PCR revealed a decrease of MICA‐specific mRNA levels upon IFN‐γ treatment and siRNA experiments pointed to an involvement of STAT‐1 in this process. Importantly, IFN‐γ‐treated MHC class I‐negative melanoma cells were less susceptible to NKG2D‐mediated NK cell cytotoxicity. Our study suggests that IFN‐γ, by down‐regulating ligand expression, might facilitate escape of MHC class I‐negative melanoma cells from NKG2D‐mediated killing by NK cells. © 2008 Wiley‐Liss, Inc.     

The comparison of biologic characteristics between mice embryonic stem cells and bone marrow derived dendritic cells

OBJECTIVE This research was to induce dendritic cells （DCs） from mice embryonic stem cells and bone marrow mononuclear cells in vitro, and then compare the biologic characteristics of them. METHODS Embryonic stem cells （ESCs） suspending cultured in petri dishes were induced to generate embryonic bodies （EBs）. Fourteen-day well-developed EBs were transferred to histological culture with the same medium and supplemented 25 ng/ml GM- CSF and 25 ng/ml IL-3. In the next 2 weeks, there were numerous immature DCs outgrown. Meantime, mononuclear cells isolated from mice bone marrow were induced to derive dendritic cells by supplementing 25 ng/ml GM-CSF and 25 ng/ml IL-4, and then the morphology, phenotype and function of both dendritic cells from different origins were examined. RESULTS Growing mature through exposure to lipopolysaccharide （LPS）, both ESC-DCs and BM-DCs exhibited dramatic veils of cytoplasm and extensive dendrites on their surfaces, highly expressed CD11c, MHC-II and CD86 with strong capacity to stimulate primary T cell responses in mixed leukocyte reaction （MLR）. CONCLUSION ESC-DC has the same biologic characteristics as BM-DC, and it provides a new, reliable source for the functional research of DC and next produce corresponding anti-tumor vaccine.     

Identification of HLA‐A2‐ and A24‐restricted T‐cell epitopes derived from SOX6 expressed in glioma stem cells for immunotherapy

Malignant gliomas are the most aggressive human primary brain tumors and are currently incurable. Immunotherapies have the potential to target glioma and glioma stem cells (GSCs) that are resistant to conventional therapies. We previously identified SOX6 as a human glioma antigen and demonstrated that vaccination with SOX6 DNA induced cytotoxic T lymphocytes (CTLs) specific for glioma, thereby exerting therapeutic antitumor responses in glioma‐bearing mice. In this study, we attempted to identify SOX6‐derived peptides as specific targets for effective and safe T‐cell‐mediated immunotherapy targeting SOX6‐positive glioma and GSCs. In vitro stimulation with human leukocyte antigen (HLA)‐A*2402 (A24)‐restricted peptides, RFENLGPQL (SOX6₅₀₄) and PYYEEQARL (SOX6₆₂₈) or the HLA‐A*0201 (A2)‐restricted peptide, ALFGDQDTV (SOX6₄₄₇) was capable of inducing SOX6 peptide‐specific CTLs in peripheral blood mononuclear cells derived from healthy donors and glioma patients. These CTLs were able to lyse a majority of glioma cell lines and a GSC line derived from human glioblastoma in an HLA Class I‐restricted and an antigen‐dependent manner. Furthermore, peptide vaccines of SOX6₆₂₈, which was conserved in the murine SOX6 protein and expected to bind to major histocompatibility complex (MHC) H‐2^d, induced CTLs specific for SOX6₆₂₈ in H‐2^d mice. Normal autologous cells from mice, in which SOX6‐specific immune responses were generated, were not destroyed. These results suggest that these SOX6 peptides are potnetially immunogenic in HLA‐A24 or ‐A2 positive glioma patients and should be considered as a promising strategy for safe and effective T‐cell‐based immunotherapy of patients with gliomas.     

The treatment of multiple myeloma using vincristine,carmustine, melphalan,cyclophosphamide, and prednisone (VBMCP) alternating with high‐dose cyclophosphamide and α2β interferon versus VBMCP

BACKGROUND:

A randomized controlled trial tested the hypothesis that aggressive initial therapy using high‐dose cyclophosphamide (HiCy) and α₂β interferon (IFN) may be superior to standard combination alkylating agent regimens in the treatment of newly diagnosed myeloma.

METHODS:

This Eastern Cooperative Oncology Group trial evaluated 268 previously untreated patients with active multiple myeloma randomized to vincristine, carmustine, melphalan, cyclophosphamide, and prednisone (VBMCP) or VBMCP plus HiCy and recombinant IFN.

RESULTS:

The overall objective response was 62% in the VBMCP regimen and 68% in the VBMCP + HiCy + IFN group. The near complete response and complete response rates were 8.1% and 8.9%, respectively. Progression‐free survival was 22.1 and 25.3 months, respectively. The median overall survival was 37.1 months for patients treated with VBMCP and 41.3 months for those treated with VBMCP + HiCy + IFN (P = .38). The 5‐year overall survival rates were not significantly different between the 2 arms: 26.4% and 33%, respectively. Lethal toxicities occurred in 15 patients, including 10 from infection, but there was no significant difference in lethal toxicities between the 2 regimens.

CONCLUSIONS:

The study showed no significant benefit with the addition of HiCy and IFN to VBMCP. Cancer 2009. © 2009 American Cancer Society.     

Targeting cancer stem cells via integrin β4

Integrins mediate cell-cell interactions and communication with the extracellular matrix (ECM). These transmembrane protein receptors allow binding between a cell and its surroundings, initiating a breadth of intracellular signaling resulting in proliferation, differentiation, survival, or migration. Such responses have made integrins an attractive target for cancer therapy. Self-renewing and highly tumorigenic cancer stem cells (CSCs) are most resistant to traditional radiation treatment and chemotherapy, and therefore may contribute directly to the metastasis and relapse of the disease. In both the 4T1 mouse metastatic mammary tumor model and SCC7 head and neck squamous cell carcinoma model, integrin β4 (ITGB4) was expressed on ALDH^high 4T1 and SCC7 CSCs. Using two immunological approaches, we targeted ITGB4 through 1) ITGB4 protein-pulsed dendritic cell (ITGB4-DC) vaccination or 2) via anti-CD3/anit-ITGB4 bispecific antibody (ITGB4 BiAb)-armed T cell adoptive transfer. These two therapies reduced ITGB4-expressing CSCs and inhibited local tumor growth and lung metastasis through ITGB4 specific cellular and humoral immune responses. Additionally, the combination of anti-PD-L1 immunotherapy with our two ITGB4-targeted approaches significantly improved treatment efficacy. We also found increased concentrations of serum IFN-γ and IL-6 in the 4T1 and SCC7 models which may help define future directions of this ITGB4-targeted study. Together, these results emphasize ITGB4 as a practical CSC immunological target with possible therapeutic benefits across tumor types with high ITGB4 expression.     

Side population of pancreatic cancer cells predominates in TGF‐β‐mediated epithelial to mesenchymal transition and invasion

We report here side population (SP) cells, a cancer stem cell enriched fraction from pancreatic cancer cell line, have enormous superior potential of the epithelial to mesenchymal transition (EMT), invasion, and metastasis. In an isolated SP cell culture, the cells rapidly expressed and up‐regulated E‐cadherin, an epithelial phenotypic marker, and the cells formed tightly contacted cell cluster, which is a representative epithelial phenotypic appearance. When the SP cells were incubated in the presence of TGF‐β, SP cells changed their shape into mesenchymal‐like appearance including spindle shaped assembly. This alteration was associated with significant reduction of E‐cadherin expression level. TGF‐β induced EMT‐associated gene alteration such as reduction of E‐cadherin mRNA and induction of Snail mRNA and matrixmetalloproteinase (MMP)‐2 mRNA. Finally, SP cells exerted notable matrigel invasion activity in response to TGF‐β treatment, whereas MP cells did not respond to TGF‐β‐mediated invasion. In conclusion, these results suggest that SP cells from pancreatic cancer cell line possess superior potentials of phenotypic switch, i.e., EMT/MET, micro‐invasion, and in vivo metastasis, as compared to MP cells. Because micro‐invasion and metastasis are key mechanisms of cancer malignant potential, SP cells would be the attractive target for preventing cancer progression. © 2008 UICC     

β‐glucan restores tumor‐educated dendritic cell maturation to enhance antitumor immune responses

Tumors can induce the generation and accumulation of immunosuppressive cells such as myeloid‐derived suppressor cells (MDSCs) in a tumor microenvironment, contributing to tumor escape from immunological attack. Although dendritic cell‐based cancer vaccines can initiate antitumor immune responses, tumor‐educated dendritic cells (TEDCs) involved in the tolerance induction have attracted much attention recently. In this study, we investigated the effect of β‐glucan on TEDCs and found that β‐glucan treatment could promote the maturation and migration of TEDCs and that the suppressive function of TEDCs was significantly decreased. Treatment with β‐glucan drastically decreased the levels of regulatory T (Treg) cells but increased the infiltration of macrophages, granulocytes and DCs in tumor masses, thus elicited Th1 differentiation and cytotoxic T‐lymphocyte responses and led to a delay in tumor progression. These findings reveal that β‐glucan can inhibit the regulatory function of TEDCs, therefore revealing a novel function for β‐glucan in immunotherapy and suggesting its potential clinical benefit. β‐Glucan directly abrogated tumor‐educated dendritic cells‐associated immune suppression, promoted Th1 differentiation and cytotoxic T‐lymphocyte priming and improved antitumor responses.     

Tumor‐associated macrophage interleukin‐β promotes glycerol‐3‐phosphate dehydrogenase activation,glycolysis and tumorigenesis in glioma cells

Tumor‐immune crosstalk within the tumor microenvironment (TME) occurs at all stages of tumorigenesis. Tumor‐associated M2 macrophages play a central role in tumor development, but the molecular underpinnings have not been fully elucidated. We demonstrated that M2 macrophages produce interleukin 1β (IL‐1β), which activates phosphorylation of the glycolytic enzyme glycerol‐3‐phosphate dehydrogenase (GPD2) at threonine 10 (GPD2 pT10) through phosphatidylinositol‐3‐kinase‐mediated activation of protein kinase‐delta (PKCδ) in glioma cells. GPD2 pT10 enhanced its substrate affinity and increased the catalytic rate of glycolysis in glioma cells. Inhibiting PKCδ or GPD2 pT10 in glioma cells or blocking IL‐1β generated by macrophages attenuated the glycolytic rate and proliferation of glioma cells. Furthermore, human glioblastoma tumor GPD2 pT10 levels were positively correlated with tumor p‐PKCδ and IL‐1β levels as well as intratumoral macrophage recruitment, tumor grade and human glioblastoma patient survival. These results reveal a novel tumorigenic role for M2 macrophages in the TME. In addition, these findings suggest possible treatment strategies for glioma patients through blockade of cytokine crosstalk between M2 macrophages and glioma cells.     

γ‐Secretase inhibitor reduces immunosuppressive cells and enhances tumour immunity in head and neck squamous cell carcinoma

Immune evasion is a hallmark feature of cancer, and it plays an important role in tumour initiation and progression. In addition, tumour immune evasion severely hampers the desired antitumour effect in multiple cancers. In this study, we aimed to investigate the role of the Notch pathway in immune evasion in the head and neck squamous cell carcinoma (HNSCC) microenvironment. We first demonstrated that Notch1 signaling was activated in a Tgfbr1/Pten‐knockout HNSCC mouse model. Notch signaling inhibition using a γ‐secretase inhibitor (GSI‐IX, DAPT) decreased tumour burden in the mouse model after prophylactic treatment. In addition, flow cytometry analysis indicated that Notch signaling inhibition reduced the sub‐population of myeloid‐derived suppressor cells (MDSCs), tumour‐associated macrophages (TAMs) and regulatory T cells (Tregs), as well as immune checkpoint molecules (PD1, CTLA4, TIM3 and LAG3), in the circulation and in the tumour. Immunohistochemistry (IHC) of human HNSCC tissues demonstrated that elevation of the Notch1 downstream target HES1 was correlated with MDSC, TAM and Treg markers and with immune checkpoint molecules. These results suggest that modulating the Notch signaling pathway may decrease MDSCs, TAMs, Tregs and immune checkpoint molecules in HNSCC.     

Prognosis of metastatic renal cell carcinoma with first‐line interferon‐α therapy in the era of molecular‐targeted therapy

The RCC‐SELECT study showed the correlation between single nucleotide polymorphisms (SNP) in STAT3 gene and survival in metastatic renal cell carcinoma (mRCC) patients with first‐line interferon‐α (IFN‐α). In that study, even patients with STAT3 SNP linked to shorter overall survival (OS) exhibited remarkably improved prognosis. All 180 patients evaluated in the above study were further analyzed for correlation between OS and demographics/clinicopathological parameters. OS was estimated using the Kaplan–Meier method. Associations between OS and potential prognostic factors were assessed using the log‐rank test and the Cox proportional hazards model. The median OS was 42.8 months. Univariate analysis showed that worse Eastern Cooperative Oncology Group‐performance status (ECOG‐PS), high T stage, regional lymph node metastasis, distant metastasis, higher grade, infiltrative growth pattern, the presence of microscopic vascular invasion (MVI), hypercalcemia, anemia, thrombocytopenia and elevated C‐reactive protein were significantly associated with OS. Multivariate analysis revealed that ECOG‐PS (hazard ratio [HR] = 3.665, P = 0.0004), hypercalcemia (HR = 6.428, P = 0.0005) and the presence of MVI (HR = 2.668, P = 0.0109) were jointly significant poor prognostic factors. This is the first study analysing prognostic factors of mRCC patients with first‐line IFN‐α using large cohort of the prospective study. The present study suggests that first‐line IFN‐α is still a useful therapy for mRCC even in the era of molecular targeted therapy.     

No interference of the 1,3‐β‐d‐glucan containing nutritional supplement ImunixX with the 1,3‐β‐d‐glucan serum test

The detection of 1,3‐β‐d ‐glucan serum levels may permit establishing the diagnosis of invasive fungal infections more early. We tested in six healthy volunteers whether the intake of a 1,3‐β‐d ‐glucan‐containing nutritional supplement leads to false‐positive 1,3‐β‐d ‐glucan levels. All levels were negative, even in two different dosing regimens.     

Treatment of chronic myeloid leukemia with autologous transplantation using peripheral blood stem cells or bone marrow cultured in IL-2 followed by IL-2, GM-CSF,and IFN-alpha administration

Interleukin-2 (IL-2) is able to generate nonspecific cytotoxic effectors from hematopoietic precursors. We evaluated the feasibility and efficacy of chronic myeloid leukemia (CML) treatment with autologous hematopoietic stem cell transplantation (HSCT) using grafts cultured in IL-2 followed by immunotherapy with IL-2, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interferon (IFN)-α. Eight patients with CML were enrolled: five in an accelerated phase and three in a chronic phase. They received peripheral blood stem cells (PBSC) or bone marrow (BM) cultured in a medium containing IL-2 for 24 h. A median of 1.29 × 10⁶ CD34+ cells/kg were infused after conditioning with busulfan (12–16 mg/kg) in PBSC recipients. BM was infused without prior myeloablative therapy. The engraftment occurred with a median of 15 d. Engraftment failure developed in one patient. The transplantation was followed by a 1-mo regimen of IL-2 (0.5 × 10⁶ IU/m² daily) and GM-CSF, and 6 mo of IFN-α. One complete and one transient minor cytogenetic remission were observed. At 24 mo after transplantation, two patients had died of progressive disease and one of infection. Five patients had stable disease in the chronic phase. Autologous transplantation using IL-2-activated graft is feasible and the subsequent IL-2, GM-CSF, and IFN-α administration has acceptable toxicity. However, no benefits in comparison with conventional autologous transplantation for CML were identified in our study. Tissue Bank, University Hospital Brno, Czech Republic     

The induction of autophagy by γ‐radiation contributes to the radioresistance of glioma stem cells

Malignant gliomas are characterized by a short median survival which is largely impacted by the resistance of these tumors tochemo‐ and radiotherapy. Recent studies suggest that a small subpopulation of cancer stem cells, which are highly resistant to γ‐radiation, has the capacity to repopulate the tumors and contribute to their malignant progression. γ‐radiation activates the process of autophagy and inhibition of this process increases the radiosensitivity of glioma cells; however, the role of autophagy in the resistance of glioma stem cells (GSCs) to radiation has not been yet reported. In this study we examined the induction of autophagy by γ‐radiation in CD133+ GSCs. Irradiation of CD133+ cells induced autophagy within 24–48 hr and slightly decreased the viability of the cells. γ‐radiation induced a larger degree of autophagy in the CD133+ cells as compared with CD133? cells and the CD133+ cells expressed higher levels of the autophagy‐related proteins LC3, ATG5 and ATG12. The autophagy inhibitor bafilomycin A1 and silencing of ATG5 and beclin1 sensitized the CD133+ cells to γ‐radiation and significantly decreased the viability of the irradiated cells and their ability to form neurospheres. Collectively, these results indicate that the induction of autophagy contributes to the radioresistance of these cells and autophagy inhibitors may be employed to increase the sensitivity of CD133+ GSCs to γ‐radiation. © 2009 UICC