IL-6 Levels Correlate with Prognosis and Immunosuppressive Stromal Cells in Patients with Colorectal Cancer.

BACKGROUND: The prognosis for patients with colorectal cancer (CRC) is determined by tumor characteristics as well as the host immune response. This study investigated the relationship between an immunosuppressive state and patient prognosis by evaluating the systemic and tumor microenvironment (TME) interleukin (IL)-6 levels. METHODS: Preoperative serum IL-6 levels were measured using an electrochemiluminescence assay. Expression of IL-6 in tumor and stromal cells was evaluated immunohistochemically in 209 patients with resected CRC. Single-cell analysis of tumor-infiltrating immune cells was performed using mass cytometry in 10 additional cases. RESULTS: Elevated serum IL-6 levels were associated with elevated stromal IL-6 levels and a poor prognosis for patients with CRC. High IL-6 expression in stromal cells was associated with low-density subsets of CD3+ and CD4+ T cells as well as FOXP3+ cells. Mass cytometry analysis showed that IL-6+ cells among tumor-infiltrating immune cells were composed primarily of myeloid cells and rarely of lymphoid cells. In the high-IL-6-expression group, the percentages of myeloid-derived suppressor cells (MDSCs) and CD4+FOXP3highCD45RA- effector regulatory T cells (eTreg) were significantly higher than in the low-IL-6-expression group. Furthermore, the proportion of IL-10+ cells in MDSCs and that of IL-10+ or CTLA-4+ cells in eTregs correlated with IL-6 levels. CONCLUSION: Elevated serum IL-6 levels were associated with stromal IL-6 levels in CRC. High IL-6 expression in tumor-infiltrating immune cells also was associated with accumulation of immunosuppressive cells in the TME.

Random migration contributes to cytotoxicity of activated CD8+ T-lymphocytes but not NK cells.

Activated lymphocytes have the ability to undergo non-directional cell movement known as random migration, although the biological role for this remains unclear. Herein, we investigated how random migration affects cytotoxicity of activated lymphocytes using time-lapse imaging analysis. The kinetics of random migration paralleled cytotoxicity in activated lymphocytes. Sphingosine-1-phosphate (S1P) and its receptor-1 (S1PR1) play an important role in lymphocyte migration. Phosphorylated FTY720 (FTYP), a structural analog of S1P, significantly inhibited random migration and cytotoxicity of activated CD3(+)NKG2D(+)CD8(+) T-lymphocytes but not CD3(-)NKG2D(+)CD56(+) natural killer (NK) cells. In a mouse xenograft model, FTYP-treated activated lymphocytes exhibited lower cytotoxicity and less tumor infiltration for activated CD3(+)NKG2D(+) T-lymphocytes but not CD3(-)NKG2D(+) NK cells. These results suggest that random migration contributes to the cytotoxicity of activated CD8(+) T-cells but not of NK cells.

An epithelial cell adhesion molecule- and CD3-bispecific antibody plus activated T-cells can eradicate chemoresistant cancer stem-like pancreatic carcinoma cells in vitro.

Cancer stem-like properties of various types of cancer, including pancreatic cancer, one of the most aggressive types, correlate with metastasis, invasion, and therapeutic resistance. More importantly, chemoresistance in cancer stem-like cells (CSLCs) is a critical problem for eradication of pancreatic cancer. Several cell surface markers, such as CD44 and epithelial cell adhesion molecule (EpCAM), are molecular targets on CSLCs of pancreatic carcinoma. In this study, we investigated whether catumaxomab, a clinical-grade bi-specific antibody that binds to both EpCAM on tumor cells and CD3 on T-cells, combined with activated T-cells can eliminate chemoresistant pancreatic CSLCs in vitro. Firstly, we established a CSLC line (MU-PK1) from human pancreatic carcinoma cells derived from a patient with chemoresistant and disseminated pancreatic cancer. These CSLCs were almost completely resistant to gemcitabine-mediated cytotoxicity up to a concentration of 10 µg/ml. The cells expressed high levels of CSLC markers (CD44 and EpCAM) and had significantly higher capacities for sphere formation, invasion, and aldehyde dehydrogenase-1 expression, which are associated with cancer stemness properties. We found that pre-treatment with catumaxomab and subsequent addition of interleukin-2/OKT3 activated autologous T-cells eliminated CSLCs during a short incubation period. Moreover, when MU-PK1 cells were cultured under hypoxic conditions, the CSLCs became more aggressive. However, the combination of cytokine-activated killer T-cells with catumaxomab successfully lysed almost all these cells. In conclusion, catumaxomab combined with activated T-cells may be a potent therapeutic modality to eradicate chemoresistant pancreatic CSLCs.

NKG2D-directed cytokine-activated killer lymphocyte therapy combined with gemcitabine for patients with chemoresistant metastatic solid tumors.

Natural-killer group 2, member D (NKG2D) is an activating receptor found on activated natural killer cells and on activated T-cells, here termed cytokine-activated killer (CAK) cells. NKG2D ligands are expressed on various human cancer types. Gemcitabine is an anticancer drug which is a less immune-destructive agent than others. Herein, we investigated the clinical efficacy and the underlying mechanisms of a combination of CAK cell infusion therapy and gemcitabine. Twenty-three patients with disseminated carcinomas were treated with chemo-immunotherapy consisting of CAK cell infusion therapy following gemcitabine treatment. To investigate the underlying mechanisms by which CAK cells synergize with gemcitabine, we used enzyme-linked immunosorbent assay, Real-time reverse transcription polymerase chain reaction assay, calcein-release assay, and adherent target detachment assay. Using these assays we determined the NKG2D ligands such as major histocompatibility complex-class I-related chain (MIC)A/B expression in carcinoma cells and the level of cellular cytotoxicity generated by treatment with gemcitabine with/without CAK cells. The tumor responses differed among the patients (n=23). In vitro experiments revealed that MICA/B protein and mRNA expression were up-regulated in several carcinoma cell lines after gemcitabine treatment. Pre-treatment with gemcitabine and subsequent exposure to CAK cells induced greater cytotoxicity than either treatment alone. Inclusion of soluble MICB in CAK cell-mediated cytotoxicity assay significantly reduced cytotoxicity. Our clinical results of gemcitabine-CAK combinatorial therapy demonstrated long-term stable disease despite chemoresistance. In conclusion, the combination of gemcitabine and CAK cells may have clinical therapeutic significance for pancreatic, hepato-biliary tract, and urothelial tract cancer. Our study shows that combining CAK therapy with gemcitabine can lead to successful treatment of metastatic cancer.

The Hedgehog inhibitor suppresses the function of monocyte-derived dendritic cells from patients with advanced cancer under hypoxia.

Immunotherapy using monocyte derived dendritic cells (Mo-DCs) from cancer patients has been developed; however, the Mo-DCs regularly studied have been derived from non-cancer bearing donors or mice, and evaluated in normoxic conditions. In the present study, we investigated the effects of Hedgehog (Hh) inhibitors which are being developed as molecular target drugs for cancer on the functions of Mo-DCs derived from patients with advanced cancer when cultured in a tumor-like hypoxic environment. Mo-DC induction, migration, chemotaxis, phagocytosis, maturation, IL-12 p40 or p70 secretion and the allogeneic lymphocyte stimulation activity of Mo-DCs from patients with advanced cancer were all significantly inhibited by the Hh inhibitor, cyclopamine under hypoxic conditions. Our results suggest that Hh signaling plays an important role in the maintenance and function of Mo-DCs derived from patients with advanced cancer when cultured under hypoxic conditions.

The Hedgehog inhibitor cyclopamine impairs the benefits of immunotherapy with activated T and NK lymphocytes derived from patients with advanced cancer.

Hedgehog (Hh) signaling is activated in various types of cancer and contributes to the progression, proliferation, and invasiveness of cancer cells. Many Hh inhibitors are undergoing clinical trial and show promise as anticancer drugs. Hh signaling is also induced in the activated T and NK (TNK) lymphocytes that are used in immunotherapy. Activated TNK lymphocyte therapy is anticipated to work well within a tumor's hypoxic environment. However, most studies on the immunobiological functions of activated TNK lymphocytes have been conducted on healthy donor samples, under normoxic conditions. In the present study, we evaluated the effects of Hh inhibition and oxygen concentrations on the function of activated TNK lymphocytes derived from patients with advanced cancer. Proliferation, migration, surface NKG2D expression, and cytotoxicity were all significantly inhibited, and IFN-γ secretion was significantly increased upon Hh inhibitor treatment of activated TNK lymphocytes under hypoxic conditions in vitro. Tumors from mice injected with cyclopamine-treated activated TNK lymphocytes showed a significant increase in tumor size and had fewer apoptotic cells compared with the tumors in mice injected with control activated TNK lymphocytes. These results suggest that Hh signaling plays a pivotal role in activated TNK lymphocyte cell function. Combination therapy using Hh inhibitors and activated TNK lymphocytes derived from patients with advanced cancer may not be advantageous.

Combining celecoxib with sorafenib synergistically inhibits hepatocellular carcinoma cells in vitro.

AIM: Sorafenib is a promising treatment for hepatocellular carcinoma (HCC) but recent toxicity concerns suggest that new strategies for its use are needed. One approach for reducing toxicity is to use lower doses of sorafenib in combination with other complementary mechanisms. Celecoxib, a cyclooxygenase-2 inhibitor, has been shown to inhibit HCC, and we hypothesized that low-dose sorafenib co-administered with celecoxib could act synergistically in the inhibition of HCC. In this study, the effect of sorafenib was tested in combination with celecoxib on the growth of human HCC cells in vitro. MATERIALS AND METHODS: Two human HCC cell lines, HepG2 and Huh7, were treated with sorafenib and celecoxib, alone and in combination, and the effect of these treatments on growth, apoptosis, and expression of phospho-AKT was evaluated by WST-8, DNA content, and immunocytochemical assays, respectively. RESULTS: When compared to the actions of either agent alone, the combination of low concentrations of sorafenib (<5 µM) and celecoxib (<20 µM) resulted in enhanced inhibition of both cell growth and AKT activation, and increased the induction of apoptosis. Combination index (CI) analysis showed that the growth inhibition effect was synergistic. CONCLUSION: This study shows that celecoxib synergistically potentiates the sorafenib-mediated antitumor effect. This finding establishes the foundation for clinical trials evaluating the efficacy of co-administration of soerafenib and celecoxib as a treatment for HCC.

Combining cetuximab with killer lymphocytes synergistically inhibits human cholangiocarcinoma cells in vitro.

AIM: We explored the possibility of combining adoptive immunotherapy with cytokine-activated killer (CAK) cells and the epidermal growth factor receptor monoclonal antibody, cetuximab, as a treatment for cholangiocarcinoma. MATERIALS AND METHODS: CAK cells were cultured with a high-dose of interleukin-2 and anti-CD3 monoclonal antibodies. This cell population contained both activated CD16+/CD56+ (NK) cells and CD3+/NKG2D(high+) T-cells. The effect of CAK cells and cetuximab, alone and in combination, on the viability of human cholangiocarcinoma cells was evaluated. RESULTS: Culture of CAK cells alone, but not cetuximab alone, exhibited modest cytotoxicity toward cholangiocarcinoma cells. However, combining CAK cells with cetuximab significantly enhanced cytotoxicity. This enhancement was inhibited by the addition of excess human immunoglobulins, suggesting that antibody-dependent cytotoxicity, mediated by activated NK cells in the CAK cell culture was involved in this mechanism. CONCLUSION: Cetuximab may be used to enhance CAK cell therapeutic activity in patients with cholangiocarcinoma, by potentiating antibody-dependent cellular cytotoxicity.

A new method for rapid cytotoxic T-lymphocyte induction using a multiple cytokine cocktail.

Immunotherapy using cytotoxic T-lymphocytes (CTLs) still has limited success. An increase in the frequency of CTL administration is one method to improve immunotherapy using CTLs. The conventional method (C-method) that generates CTLs after the induction of dendritic cells requires a long time period. If CTLs can be more rapidly and simply induced, the frequency of immunotherapy could be increased and unexpected contamination could be avoided. In this study, in order to more rapidly induce functional CTLs, we investigated a new method (N-method) that uses a cytokine cocktail, including interleukin (IL)-2, IL-4, granulocyte macrophage colony-stimulating factor, tumour necrosis factor-α and interferon-α, together with a tumour lysate. CTLs induced by the N-method had equivalent functions, such as proliferation, surface antigen expression and cytotoxicity, compared with those induced by the C-method. These results suggest that the N-method can substitute the C-method in order to improve the effect of immunotherapy using CTLs.

Combinatorial cytotoxicity of gemcitabine and cytokine-activated killer cells in hepatocellular carcinoma via the NKG2D-MICA/B system.

AIM: Natural-killer group 2, member D (NKG2D) is an activating receptor on natural killer cells and activated T-cells, designated cytokine-activated killer (CAK) cells here. The MHC class I chain-related A and B (MICA and MICB, respectively) are ligands of NKG2D and are expressed on various human tumor cells, including hepatocellular carcinoma (HCC) cells. Here, we investigate whether gemcitabine, a chemotherapeutic agent, affects MICA/B expression in HCC. MATERIALS AND METHODS: We used ELISA, RT-PCR and adherent target detachment assays to determine expression of MICA/B in HepG2 HCC cells and the level of cellular cytotoxicity generated by treatment with gemcitabine and/or CAK cells. RESULTS: Surface expression of MICA/B was evident after gemcitabine treatment, and MICB-specific mRNA was up-regulated. Pre-treatment with gemcitabine and subsequent exposure to CAK cells induced greater cytotoxicity than either treatment alone. Inclusion of soluble MICB significantly reduced cytotoxicity. CONCLUSION: Gemcitabine induced MICA/B expression in HepG2 cells, resulting in synergistic enhancement of the cytotoxic effects of NKG2D-high CAK cells. The combination of gemcitabine and CAK cells may have clinical therapeutic significance for HCC.

Induction and high density culture of human hepatoblasts from fetal hepatocytes with suppressing transformation.

It is well known that it would be important to cultivate human hepatocytes of about 10(10) cells at a high cell density, about 1 x 10(7) cells/cm(3), in the bioreactor for the development of bioartificial liver. However, since primary human hepatocytes lack an ability to proliferate in vitro, it is essential to establish a culture method for the proliferation of normal human hepatic stem cells as a cell source. In this study, it was found that human hepatoblasts, a kind of hepatic stem cells, were induced from human fetal hepatocytes while keeping the ability of proliferation by the treatment of 1mM sodium butyrate (SB) for 12 d of culture. The transformation of hepatoblasts was evaluated by abnormal prothrombin (PIVKA-II) assay, which is a clinical marker for hepatocellular carcinoma. The PIVKA-II production rate of the cells was suppressed to the normal level under 1 mM SB. The cells including hepatoblasts under 1 mM SB attached to the porous hydroxyapatite carriers and proliferated to a high cell density of about 1 x 10(7) cells/cm(3) in the carriers. The liver-specific function, cytochrome P450 3A4 activity (4.2 pmol/mg protein/min) of the cells in the carriers under 1 mM SB was comparable to that of primary human hepatocytes. Ammonia metabolizing activity (0.21 micromol/10(6) cells/h) of the cells was also comparable to that of porcine hepatocytes used in the bioartificial liver. The PIVKA-II production rate of the cells in the carrier was suppressed to the normal level. These results suggested that induction of human hepatoblasts from fetal hepatocytes by the treatment of 1mM SB and proliferation of the cells at a high cell density using hydroxyapatite carriers should be one of the more promising culture methods for bioartificial liver developments.