Clofarabine induces hypomethylation of DNA and expression of Cancer-Testis antigens.

In this study, treatment of lymphoid tumor cells with low dose clofarabine upregulated the expression of Sp17 and SPAN-Xb. This was associated with an increase in hypomethylated CpG dinucleotides and a decrease in global DNA methylation, as demonstrated by decreases in the percent of methylated Alu repeats. The most optimal concentration of clofarabine to induce DNA hypomethylation and CT antigen expression was between 1x10(-9) and 1x10(-8)M. Above this, clofarabine resulted in tumor cell growth inhibition and apoptosis. Our results provide the first evidence for the CT antigen-inducing and DNA hypomethylating property of low concentration clofarabine.

SEMG-1 expression in early stage chronic lymphocytic leukemia.

BACKGROUND AIMS: Chronic lymphocytic leukemia (CLL) is an indolent disease. It is currently recommended that patients with CLL stages 0 and I follow a watchful waiting strategy. These patients are, therefore, a suitable group for testing immunotherapeutic approaches to avoid problems of immunosuppression as a result of disease progression and chemotherapy. In this study, we investigated the expression of SEMG-1 in early CLL to determine the suitability of SEMG-1 as a target for further development of tumor vaccines for early CLL. METHODS: A combination of reverse transcriptase (RT)-polymerase chain reaction (PCR) and immunocytochemistry was used to evaluate the expression of SEMG-1 in early CLL. The results were correlated with Zap 70 expression. Recombinant SEMG-1 protein was used in an enzyme-linked immunosorbent assay (ELISA) to determine the presence of SEMG-1 antibodies (Ab) in serum from these patients. RESULTS: The SEMG-1 gene was expressed in 19/41 (46%) patients with early CLL. Gene expression was associated with protein synthesis in CLL cells. Protein expression, however, was heterogeneous within individual patients. Only transcripts encoding the SEMG-1(50) variant and not SEMG-1(43) were detected. SEMG-1(50) was expressed irrespective of the Zap 70 status. High-titer SEMG-1 IgG but not IgM Ab were detected in some of these patients, suggesting that SEMG-1-reactive immune responses are intact within the immune repertoire of early CLL patients. CONCLUSIONS: SEMG-1 is expressed in nearly half of patients with early CLL and may be a target for further investigations into its use for immunotherapy of early CLL.

Immunosuppressive diacetylenes, ceramides and cerebrosides from Hydrocotyle leucocephala.

Three C-17 diacetylenic compounds (1-3), one monoterpenoid (4), seven ceramides (leucoceramides A-G, 5a-g), six cerebrosides (leucocerebrosides A-F, 6a-f) and nine known compounds were isolated from the methanolic extract of Hydrocotyle leucocephala. Their structures were established by spectroscopic methods. The isolated compounds 1-3, 5a-g, 6a-f and 7 were shown to be active in the lipopolysaccharide (LPS) induced cytokine production assay for IL-10, IL-12, and TNF-alpha.

Mechanism of anticancer host response induced by OK-432, a streptococcal preparation, mediated by phagocytosis and Toll-like receptor 4 signaling.

It has previously been reported by our group that Toll-like receptor (TLR) 4 is involved in anticancer immunity induced by OK-432, a Streptococcus-derived immunotherapeutic agent. However the detailed mechanism of the OK-432-induced immune response via TLR4 remained uncertain, because it may not be possible for OK-432, which consists of whole bacterial bodies, to bind directly to TLR4. In the current study, we conducted in vitro and in vivo experiments to investigate the hypothesis that OK-432 may first be captured and dissolved by phagocytes and that the active components released by the cells may then induce host responses via TLR4. TS-2 monoclonal antibody, which recognizes an active component of OK-432 designated OK-PSA was used in the current study. First, it was observed that OK-432-induced cytokine production by dendritic cells (DCs) and macrophages was significantly inhibited in vitro by cytochalasin B, a phagocytosis inhibitor. Immunofluorescence staining using TS-2 demonstrated that OK-432 was captured and dissolved by phagocytes. OK-PSA was detected in the supernatants derived from OK-432-treated DC culture by enzyme-linked immunosorbent assay using TS-2. Supernatants from OK-432-treated DC culture increased nuclear factor (NF)-kappaB activity in TLR4-expressing cells, and the increased activity was inhibited by TS-2 antibody. OK-432 itself did not activate NF-kappaB in these cells. In in vivo experiments, the anticancer effect of OK-432 was significantly inhibited by suppression of phagocytosis activity by cytochalasin B. In this case, the amount of OK-PSA, an active component of OK-432, in the sera was also reduced by cytochalasin B. These findings elucidated the mechanism mediated by phagocytosis and TLR4 signaling in the immune effect of OK-432.

[The relationship between gene expression of Bcl-2 and Bax and the therapeutic effect in oral cancer patients].

We have investigated the relationship between gene expression of Bcl 2 and Bax and the therapeutic effect in oral cancer patients. A significant correlation between Bcl-2/Bax gene expression ratio in the peripheral blood mononuclear cells (PBMCs) from the patients, and the therapeutic effect of radiation therapy in combination with UFT and OK-432, as well as survival rate, was observed. In addition, the statistically significant correlation was also observed between Bcl-2/Bax ratio and IFN-gamma and NK activity induced with OK-432. These findings suggest that Bcl-2 and Bax gene expression in PBMCs may be useful as a prognostic factor in oral cancer patients.

[Anti-tumor immunity induced by OK-432-derived DNA].

We have tried to identify the effective components of OK-432, a Streptococcus-derived anti-cancer immunotherapeutic agent. In the current study, we investigated the effect of OK-432-derived DNA (OK-DNA) in augmenting anti-cancer immune response. Analysis of OK-DNA with the restriction enzymes Hpa II and Msp I revealed that OK-DNA contained unmethylated CpG motifs. OK-DNA induced Th1-type cytokines, such as IFN-gamma and IL-12, and augmented killer cell activities in vitro on human peripheral blood mononuclear cells, whereas the methylated OK-DNA did not. Cytokines were also produced by OK-DNA-stimulated splenocytes derived from wild-type mice but not from TLR9-deficient mice. In the in vivo study, a peritumoral administration of OK-DNA resulted in a significant inhibition of tumor growth in syngeneic tumor-bearing wild-type and TLR4-deficient mice but not in TLR9-deficient mice. Anti-tumor effect of OK-432 in TLR9-deficient mice was significantly but partially reduced as compared with that in wild-type mice, while the effect of OK-432 was almost completely eliminated in TLR4-deficient mice. These findings suggest that unmethylated CpG-DNA in OK-432 functions as an active component in OK-432-induced anti-cancer immunity via TLR9, at least in part.

[Induction of apoptosis in human head and neck cancer cell lines by an active component of OK-432 through p53-independent pathway via toll-like receptor (TLR) 4 signaling].

OK-PSA, an active component of OK-432, induces anti-tumor immunity via Toll-like receptor (TLR) 4/MD-2 complex. In the current study, we evaluated the effect of the OK-PSA on human head and neck cancer cell lines. Twelve cancer cell lines including 7 squamous cell carcinoma (SCC) cell lines and 5 salivary gland cancer (SGC) cell lines were examined. The quantitative real-time PCR analysis revealed that TLR4 mRNA was expressed in all 12 cell lines, and that MD-2 mRNA was expressed in 5 cell lines. OK-PSA stimulation resulted in the activation of NF-kappaB in the 4 SCC cell lines which express both TLR4 and MD-2 genes, and in 5 SGC cell lines which express at least TLR4 gene independently of MD-2 expression. In these OK-PSA-responsive cell lines, OK-PSA activated caspase-1, caspase-3 and caspase-8, and induced apoptosis. OK-PSA-induced apoptosis were observed even in a SGC cell line in which p53 is mutated and its function is impaired. These findings strongly suggest that OK-PSA induces apoptosis by the activation of caspases through p53-independent pathway via TLR4 signaling in head and neck cancer cells.

[Radiation, 5-FU and OK-432: inhibitory effect of IL-10 and TGF-beta].

We investigated the effect of 5-FU and radiation in OK-432-induced cytokine production. Stimulation of peripheral blood mononuclear cells (PBMCs) with OK-432 (1 micro/ml) for 24 h induced Th1-type cytokines (IFN-gamma, TNF-alpha, IL-12, IL-18) as well as IL-10 and TGF-beta. When the PBMCs were stimulated by 5-FU (5 microg/ml) or X-ray (2 Gy) simultaneously with OK-432, production of IL-10 and TGF-beta was significantly inhibited, while no significant change in Th1 cytokine production was observed. Although OK-432 also enhanced the expression of the genes encoding SOCS-1 and SOCS-3, which are negative regulators for cytokine signaling, this was reduced by 5-FU or X-irradiation. Induction of IL-10 and TGF-beta by OK-432 was significantly decreased by adding antisense ODN for SOCS-1 or that for SOCS-3. Radiation and 5-FU induce Th1-dominant state by inhibiting the OK-432-induced production of IL-10 and TGF-beta mediated by regulation of SOCS-1 and SOCS-3 expression, and are suggested to increase anti-cancer immunity.

Biyouyanagin A, an anti-HIV agent from Hypericum chinense L. var. salicifolium.

[structure: see text] A structurally unique hydrophobic compound, biyouyanagin A, was isolated from the MeOH extract of the leaves of Hypericum chinense L. var. salicifolium. The structure of biyouyanagin A was elucidated on the basis of spectroscopic evidence. Biyouyanagin A showed a significant activity against HIV and inhibited cytokine production.

Cyclobutane dimers from the Colombian medicinal plant Achyrocline bogotensis.

Five cyclobutane dimers, achyrodimers A-E (1-5), along with 11 known compounds were isolated from the methanol extract of the Colombian medicinal plant Achyrocline bogotensis. Their structures were elucidated by spectroscopy. Several of these compounds were screened for cytokine-inducing activity in human peripheral blood mononuclear cells.

Chemical constituents from the Colombian medicinal plant Maytenus laevis.

The methanol extract of the bark of the Colombian medicinal plant Maytenus laevis gave six new compounds and 28 known compounds. The structures of the new and known compounds were elucidated on the basis of spectroscopic evidence. Several of these compounds were screened for cytokine-inducing activity on human PBMCs to investigate antitumor effects, and canophyllol (12) demonstrated the most effective induction of the cytokines.

[Anti-tumor effect of intratumoral administration of dendritic cells in combination with TS-1 and OK-432].

We investigated the in vivo anti-tumor effect of intratumoral administration of dendritic cells (DCs) after chemotherapy using TS-1, and followed by immunopotentiator OK-432. Both in Meth-A-bearing BALB/c and in SCCV II-bearing C3H/HeN mice, one week of oral administration of TS-1 affected a partial eradication of established tumors. TS-1 followed by DCs and OK-432 resulted in a marked inhibition in tumor growth, and also contributed to a greater prolongation of survival. Cytotoxic activities of tumor-infiltrating lymphocytes and draining lymph node cells against inoculated tumor cells were significantly increased by the therapy. Cytotoxic memory T cells were also induced. The same therapy was also applied to SCCV II-bearing C3H/HeJ mice in which the Toll-like receptor (TLR) 4 is mutated; no immunotherapeutic effect was observed in the mice. These findings suggest that local DC therapy in combination with TS-1 and OK-432 may well be a useful strategy for the treatment of solid tumors, and that TLR4 signaling is involved in the success of this therapy.

[Analysis of the immuno-activation mechanism of OK-432--phagocytosis, release of active components and TLR4 signaling].

Although we have reported that Toll-like receptor (TLR) 4 is involved in OK-432-induced anti-cancer immunity, its detailed mechanism remained uncertain. We hypothesized that OK-432 may first be captured, dissolved by phagocytes, and then active components released from the cells may stimulate TLR4. This hypothesis was examined by the current in vitro experiments. We used TS-2 MoAb which recognizes OK-PSA, an active component of OK-432. First, we observed that OK-432-induced cytokine production by dendritic cells (DCs) and macrophages was significantly inhibited by cytochalasin B, a phagocytosis inhibitor. Immunofluorescence staining by using TS-2 clearly demonstrated that OK-432 was captured and dissolved by these cells. OK-PSA was detected in the supernatants derived from OK-432-treated DC culture by ELISA with TS-2. The supernatants from OK-432-treated DC culture, but not from untreated DC culture, increased NF-kappaB activity in TLR4-expressing cells. The increased NF-kappaB activity was inhibited by TS-2. These findings elucidated the mechanism mediated by phagocytosis and TLR4 signaling in the OK-432 action.

[Anti-cancer effect of an intratumoral injection of dendritic cells expressing TLR4 in combination with an active component of OK-432 in TLR4-deficient mice].

A lipoteichoic acid-related molecule OK-PSA is an active component of OK-432. In the in vitro experiments, OK-PSA enhanced expression of MHC class II, CD80 and CD86, as well as IL-12 production on dendritic cells (DCs) were derived from wild-type mice, but not from TLR4-deficient (TLR4-/-) mice. Next we examined the in vivo anti-cancer effect of intratumoral administration of syngeneic DCs followed by OK-PSA against established tumors in mice. Although OK-PSA augmented anti-tumor effect of DC administration in tumor-bearing wild-type mice, anti-tumor effect of DCs and OK-PSA was not significant in TLR4-/- mice. Interestingly, an administration of wild-type mice-derived DCs followed by OK-PSA exhibited a marked anti-tumor effect even in TLR4-/- mice. These findings suggest that OK-PSA may be a potential adjuvant for local DC therapy, and that DC therapy followed by OK-PSA is able to elicit anti-cancer activity even in TLR4-deficient host when TLR4 is expressed only in DCs injected intratumorally.

Anti-tumor effect of an intratumoral administration of dendritic cells in combination with TS-1, an oral fluoropyrimidine anti-cancer drug, and OK-432, a streptococcal immunopotentiator: involvement of toll-like receptor 4.

The authors investigated the in vivo anti-tumor effect of intratumoral administration of bone marrow-derived dendritic cells (DCs) after chemotherapy using an oral fluoropyrimidine anti-cancer drug TS-1, and followed by immunotherapeutic agent OK-432, in two syngeneic tumor-bearing mouse models. Both in Meth-A fibrosarcoma-bearing BALB/c mice and in SCCVII-bearing C3H/HeN mice, 1 week of oral administration of TS-1 effected partial eradication of established tumors. Intratumoral injection of DCs and OK-432 caused only slight inhibition of the tumor growth. However, TS-1 administration followed by DCs and OK-432 resulted in a marked inhibition in the tumor growth and also contributed to a greater prolongation of survival. By the injection of DCs and OK-432 after TS-1 administration, a significant infiltration of immune cells, especially CD8+ T cells, was observed. Furthermore, the cytotoxic activities of tumor-infiltrating lymphocytes and draining lymph node cells against inoculated tumor cells were significantly increased by the therapy, while activities against nonspecific target cells were not. Cytotoxic memory T cells were also induced; the main effectors were MHC class I-restricted, CD8+ T cells. The same therapy was also applied to SCCVII-bearing C3H/HeJ mice in which the Toll-like receptor (TLR) 4 is mutated and its function impaired; no immunotherapeutic effect was observed in the TLR4-deficient mouse model. These findings suggest that the local DC therapy in combination with TS-1 and OK-432 may be a useful strategy for the treatment of solid tumors, and that TLR4 signaling is involved in the success of this therapy.

Expression of toll-like receptor 4 on dendritic cells is significant for anticancer effect of dendritic cell-based immunotherapy in combination with an active component of OK-432, a streptococcal preparation.

A lipoteichoic acid-related molecule OK-PSA is an active component of OK-432, a Streptococcus-derived anticancer immunotherapeutic agent. In the present study, we first examined the effect of OK-PSA on the maturation of dendritic cells (DCs) in vitro by using the DCs derived from 5 healthy donors and 10 patients with head and neck cancer with or without expression of toll-like receptor 4 (TLR4) or MD-2 mRNA. OK-PSA treatment effectively increased the surface expression of MHC class II, CD80, CD83, and CD86. OK-PSA-stimulated DCs secreted the cytokines that can induce helper T-cell 1 (Th1)-type T-cell response, and stimulated allogeneic T cells to produce IFN-gamma and to elicit an allogeneic antigen-specific cytotoxicity. These activities almost depended on expression of TLR4 and MD-2 genes. We next investigated the in vivo anticancer effect of intratumoral administration of syngeneic DCs followed by OK-PSA against established tumors in mice. C57BL/6 mice, which express wild-type TLR4, and C57BL/6-derived TLR4-knockout (TLR4(-/-)) mice were used. Although OK-PSA accelerated the antitumor effect of intratumoral DC administration in wild-type mice bearing syngeneic tumors, the antitumor effect of OK-PSA as well as of the combination therapy with DCs and OK-PSA was not significant in TLR4(-/-) mice. Interestingly, an administration of wild-type-mouse-derived DCs followed by OK-PSA exhibited a marked antitumor effect even in the TLR4(-/-) mice. These findings suggest that OK-PSA may be a potent adjuvant for local DC therapy, and that DC therapy followed by OK-PSA is able to elicit anticancer activity even in a TLR4-deficient host when TLR4 is expressed only in DCs injected intratumorally.

Involvement of Toll-like receptor 4 signaling in interferon-gamma production and antitumor effect by streptococcal agent OK-432.

BACKGROUND: The streptococcal agent OK-432 has been used for immunotherapy of head and neck cancer, among other malignancies, but its mechanism of action is unknown. Because the Toll-like receptor 4 (TLR4)/MD-2 complex is important in enabling the mammalian immune system to recognize bacterial components, we investigated whether expression of the TLR4 and MD-2 genes is associated with OK-432-induced anticancer immunity. METHODS: Peripheral blood mononuclear cells (PBMCs) from 28 patients with head and neck cancer were analyzed for TLR4 and MD-2 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR) analysis. PBMCs were treated in vitro with OK-432 or with OK-PSA (a lipoteichoic-acid-related molecule that is an active component of OK-432), and interferon-gamma (IFN-gamma) mRNA expression, an immune response measure, was analyzed by RT-PCR. Patient sera collected 24 hours after OK-432 administration were examined for IFN-gamma protein using an enzyme-linked immunosorbent assay. Lewis lung carcinoma-bearing wild-type C57BL/6 and TLR4-deficient mice (four mice per group) received intraperitoneal injections of OK-432, and tumor volumes and sera IFN-gamma levels were measured over time. All statistical tests were two-sided. RESULTS: Twenty patients expressed both TLR4 and MD-2. Expression of TLR4 and MD-2 genes was associated with the in vivo IFN-gamma induction in 19 patients administered OK-432 (Fisher's exact test P<.001). Although both OK-432 and OK-PSA induced IFN-gamma expression from PBMCs in vitro, expression of TLR4 and MD-2 was associated only with IFN-gamma expression induced by OK-PSA (P<.001). In vivo intraperitoneal administration of OK-432 resulted in an increase of IFN-gamma in sera from wild-type mice but not in sera from TLR4-deficient mice. Tumors in wild-type mice treated with OK-432 were statistically significantly smaller than those in mice treated with saline (P =.007). By contrast, in TLR4-deficient mice, there was no difference in tumor volume between the two treatment groups. CONCLUSIONS: TLR4 and MD-2 may mediate OK-432-induced anticancer immunity.

Enhancement of anti-tumor immunity by lipoteichoic acid-related molecule isolated from OK-432, a streptococcal agent, in athymic nude mice bearing human salivary adenocarcinoma: role of natural killer cells.

BACKGROUND: OK-PSA, a lipoteichoic acid (LTA)-related molecule isolated from a streptococcal agent OK-432, enhances anti-tumor immunity as a potent inducer of Th1-type cytokines. Recently, we obtained the data suggesting that natural killer (NK) cells may play a significant role for OK-PSA-induced cytokine production in vitro. MATERIALS AND METHODS: We conducted the animal experiments using athymic nude mice bearing human salivary adenocarcinoma to examine the role of NK cells in OK-PSA-induced anti-tumor immunity. OK-PSA was peritumorally injected into the mice. Cytokines in the sera were analyzed by ELISA. mRNAs for cytokines were detected by RT-PCR. 51Cr release test was performed to measure killer cell activities. RESULTS: OK-PSA markedly increased the amounts of IFN-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, IL-12 and IL-18 that are generally called "Th1-type cytokines" in the sera derived from tumor-bearing nude mice, and also accelerated the killing activities of tumor-infiltrating lymphocytes as well as of draining lymph node cells. Furthermore, OK-PSA administration resulted in significant inhibition of tumor growth, but the effect of OK-PSA was almost completely inhibited by the deletion of NK cells using anti-asialo GM1 antibody. CONCLUSION: These findings strongly suggested that NK cells are closely involved in OK-PSA-mediated anti-tumor immunity.