Enhancement of antitumor natural killer cell activation by orally administered Spirulina extract in mice.

Oral administration of hot-water extract of Spirulina, cyanobacterium Spirulina platensis, leads to augmentation of NK cytotoxicity in humans. Here, we applied to syngeneic tumor-implant mice (C57BL/6 versus B16 melanoma) Spirulina to elucidate the mechanism of raising antitumor NK activation. A B16D8 subcell line barely expressed MHC class I but about 50% expressed Rae-1, a ligand for NK activation receptor NKG2D. The Rae-1-positive population of implant B16 melanoma was effectively eliminated in the tumor mass progressed in mice. This antitumor activity was induced in parallel with IFN-gamma and abolished in mice by treatment with asialoGM-1 but not CD8beta Ab, suggesting the effector is NK cell. NK cell activation occurred in the spleen of wild-type mice medicated with Spirulina. This Spirulina-mediated enhanced NK activation was abrogated in MyD88 -/- mice but not in TICAM-1 -/- mice. The NK activating properties of Spirulina depending on MyD88 were confirmed with in vitro bone marrow-derived dendritic cells expressing TLR2/4. In D16D8 tumor challenge studies, the antitumor effect of Spirulina was abolished in MyD88 -/- mice. Hence, orally administered Spirulina enhances tumoricidal NK activation through the MyD88 pathway. Spirulina exerted a synergistic antitumor activity with BCG-cell wall skeleton, which is known to activate the MyD88 pathway via TLR2/4 with no NK enhancing activity. Spirulina and BCG-cell wall skeleton synergistically augmented IFN-gamma production and antitumor potential in the B16D8 versus C57BL/6 system. We infer from these results that NK activation by Spirulina has some advantage in combinational use with BCG-cell wall skeleton for developing adjuvant-based antitumor immunotherapy.

Proliferation of estrogen-responsive mouse tumor cell line B-1F stimulated by Saiboku-to, but inhibited by Scutellaria baicalensis, a component of Saiboku-to.

We have demonstrated that the proliferation of estrogen-responsive mouse Leydig tumor cell line B-1F is induced via suppression of 5-lipoxygenase activity followed by decrease of leukotrienes (LTs). Additionally, it has been reported that LTD4 induces apoptosis in B-1F cells. In this study, we examined effects of Saiboku-to, a traditional Chinese medicine having suppressive activities for LT production and release, on the proliferation. Saiboku-to promoted, but Scutellaria baicalensis, one of components (herbs) of Saiboku-to, significantly inhibited the proliferation of B-1F cells in vitro and in vivo. The action of Scutellaria baicalensis in B-1F cells was studied in more detail. Although Scutellaria baicalensis consists of flavonoids, iridoids, volatile oils and others, it and its major constituents had no direct effect on estrogen binding sites in B-1F cells. B-1F cells treated with Scutellaria baicalensis showed morphological changes such as nuclear aggregation and fragmentation. DNA fragmentation was also observed, indicating that Scutellaria baicalensis induces apoptosis in B-1F cells and that it or its constituents might be a good resource for searching new drugs, especially anti-cancer drugs. Moreover, Saiboku-to promoted B-1F cell proliferation, but Scutellaria baicalensis inhibited it, showing complexity of action of traditional Chinese medicines.

Adjuvant-mediated tumor regression and tumor-specific cytotoxic response are impaired in MyD88-deficient mice.

The Mycobacterium bovis bacillus Calmette-Guérin cell-wall skeleton (BCG-CWS) activates Toll-like receptor (TLR) 2 and TLR4, but unlike the typical TLR4 agonist bacterial lipopolysaccharide barely induces type 1 IFN. BCG-CWS has been used for adjuvant immunotherapy for patients with cancer. We investigated the adjuvant potential of BCG-CWS for induction of CTLs subsequent to TLR-mediated dendritic cell (DC) maturation, using a syngeneic mouse tumor model (B16 melanoma in C57BL/6). We evaluated the retardation of tumor growth and cytotoxic response in wild-type and MyD88-/- mice immunized with tumor debris and/or BCG-CWS. Delays in tumor growth and cytotoxic response were induced by immunization with a mixture of BCG-CWS emulsion and the tumor. BCG-CWS was capable of activating DCs ex vivo by the criteria of CD80/CD86 up-regulation and cytokine (interleukin-12, tumor necrosis factor-alpha) induction. Efficient tumor suppression and ex vivo cytokine induction did not occur in MyD88-deficient mice and cells, suggesting that the MyD88 adapter is crucial for induction of tumor cytotoxicity. Because TLR4 is involved in both MyD88-dependent and -independent pathways and the latter affects DC maturation, our findings indicate that both pathways cooperate to induce CTL-based tumor immunity.

Activation of the human innate immune system by Spirulina: augmentation of interferon production and NK cytotoxicity by oral administration of hot water extract of Spirulina platensis.

Spirulina platensis is a cyanobacterial species that is surmised to potentiate the immune system leading to suppression of cancer development and viral infection. Here, we identified the molecular mechanism of the human immune potentiating capacity of Spirulina by analyzing blood cells of volunteers with pre and post oral administration of hot water extract of Spirulina. NK functions represented by IFN gamma production and cytolysis were enhanced after administration of Spirulina in >50% subjects. IFN gamma was produced in an IL-12/IL-18-dependent fashion. In vitro stimulation of blood cells with BCG cell wall skeleton (CWS) allowed more potent IL-12 p40 production in cells from volunteers given Spirulina than in cells without pre-exposure to Spirulina. As BCG-CWS serves as a ligand for Toll-like receptor (TLR) 2 and 4 to raise the maturation stage of monocytes/macrophages, Spirulina may be involved in the signaling responses through Toll in blood cells even when orally administered. These observations indicated that in humans Spirulina acts directly on myeloid lineages and either directly or indirectly on NK cells. The presence of co-operative IL-12 and IL-18 is critically important for NK-mediated IFN gamma production.

The pure anti-androgen bicalutamide inhibits cyclin A expression both in androgen-dependent and -independent cell lines.

We investigated the effects of testosterone and the pure anti-androgen, bicalutamide, on DNA synthesis and cell cycle in androgen-sensitive or -insensitive human and mouse cell lines by 3H-thymidine incorporation, flow cytometry, RT-PCR and Western blotting. In androgen-dependent mouse SC-3 cells, testosterone induced DNA synthesis, shift of cell cycle distribution from G0/G1 to S/G2/M and expression of cyclin A. The induction was preceded by that of fibroblast growth factor 8 (FGF-8), and completely blocked by monoclonal antibody to FGF-8. Dihydrotestosterone (DHT) induced cyclin A expression in androgen-sensitive human prostate cancer cells, but not in androgen-independent cell lines. Bicalutamide almost completely inhibited these androgen-dependent effects both in LNCaP and SC-3 cells, but had no or limited effect on androgen-independent or FGF-8-induced DNA synthesis, and FGF-8 induced cyclin A expression. Interestingly, bicalutamide inhibited both DNA synthesis and the cyclin A expression in androgen-independent human cell lines in serum-free condition. A MEK1/2 inhibitor U0126 blocked both androgen- and rFGF-8-induced DNA synthesis. Overall, bicalutamide inhibits the cyclin A expression possibly by inhibiting FGF-8 mRNA expression and FGF-8 protein secretion but not by inhibiting FGF receptor (FGFR) signalling in androgen-dependent cell lines, and by other mechanisms in androgen-independent cell lines. The results suggest that combination with compounds such as FGFR signalling inhibitors may provide additional benefits to anti-androgens. It is also suggested that cyclin A could be a sensitive marker for androgen-induced cancer growth and for the growth inhibitory effects of anti-androgen.

High levels of RAE-1 isoforms on mouse tumor cell lines assessed by anti-"pan" RAE-1 antibody confer tumor susceptibility to NK cells.

Two sublines of the benzpyrene-induced mouse hepatoma cell line, G-1 and G-5, showed low and high metastatic ability, respectively, to the lung. We produced a polyclonal antibody (pAb) against RAE-1alpha. Five isoforms of RAE-1 have been identified to date, and this pAb recognized all isoforms and was named anti-"pan" RAE-1 pAb. The level of RAE-1 was approximately 5-fold higher in G-5 than in G-1, which was almost RAE-1-negative, as determined using anti-pan RAE-1 pAb. Expression levels of other markers including MHC class I (MHC-I) and Qa-1b were very low and indistinguishable in these sublines. NK-mediated cytotoxicity was determined with these sublines; G-5 was highly susceptible to NK-mediated cytolysis, while G-1 was relatively resistant. The NK-mediated G-5 > G-1 killing profile was diminished if the G-5 cells were pretreated with F(ab)(2)(') of anti-pan RAE-1 pAb. G-1, when transfected with Rae-1alpha cDNA, acquired NK-responsiveness similar to that of G-5. These and additional data using mouse cell lines with low MHC-I levels and various RAE-1 levels also demonstrated that RAE-1 level is critically associated with NK-susceptibility in tumor cells.