alpha-Galactosylceramide enhances the protective and therapeutic effects of tumor cell based vaccines for ovarian tumors.

Ovarian cancer is one of the leading causes of death from gynecological cancers in the United States. Conventional therapies are unlikely to control advanced stage ovarian cancers, thus requiring innovative alternative therapies. In the current study, we characterized the therapeutic effect of tumor cell-based vaccines combined with the adjuvant, alpha-galactosylceramide (alpha-GalCer) using two different mouse models. Our data suggests that treatment with alpha-GalCer led to an increase in the IFN-gamma serum levels in the presence or absence of irradiated mouse ovarian surface epithelial tumor cells (MOSEC). Furthermore, administration of irradiated MOSEC tumor cells with adjuvant alpha-GalCer generated significant protective and therapeutic antitumor effects against MOSEC tumors in vaccinated C57BL/6 mice. In addition, immune cells expressing CD4, CD8 or NK1.1 markers were found to be important for the protective antitumor effects generated by irradiated tumor cell-based vaccines combined with adjuvant alpha-GalCer. We also found that treatment of a spontaneous ovarian cancer murine model, the Müllerian inhibiting substance type II receptor T antigen (TgMISIIR-TAg) transgenic mice with ovarian tumor cell-based vaccines combined with adjuvant alpha-GalCer led to prolonged survival as well as increased numbers of tumor-specific CD8+ T cells. Therefore, irradiated tumor cell-based vaccines in combination with alpha-GalCer are capable of breaking immune tolerance and generating significant antitumor effects in two different mouse tumor models. Our study serves as a foundation for future clinical translation.

The use of doxorubicine at low doses for elevation of LAK-activity toward explants and cells of MC-rhabdomyosarcoma and B16 melanoma resistant to doxorubicin.

AIM: To study the influence of doxorubicin at low doses on antitumor action of activated (LAK) and non-activated lymphocytes from lymph nodes toward tumor cells of mice bearing doxorubicin-resistant and doxorubicin-sensitive transplantable MC-rhabdomyosarcoma and B16 melanoma. MATERIALS AND METHODS: The study was carried out on BALB/c mice bearing MC-rhabdomyosarcoma and 57BL/6 mice bearing 16 melanoma. Explants, tumor cells and lymphocytes were cultivated in diffusion chambers, filters were stained with hematoxylin by Karachi, and morphology of preparations was examined. RESULTS: At the day 7 of tumor growth in mice bearing resistant MC-rhabdomyosarcoma, non-activated lymphocytes pretreated with low-dose doxorubicin possess the highest antitumor activity, and in mice bearing doxorubicin-resistant B16 melanoma the highest antitumor activity was detected for lymphocytes after combined cultivation with IL-2 and doxorubicin. At the day 14 of tumor growth, LAK obtained from lymphocytes pretreated with doxorubicin possess the highest cytotoxic activity toward resistant tumor cells both of MC-rhabdomyosarcoma and B16 melanoma. There was no such effect in the case of sensitive tumors. CONCLUSION: To elevate antitumor activity of LAK toward MC-rhabdomyosarcoma and B16 melanoma cells, low doses of doxorubicin could be used at certain conditions of LAK generation.

Resistance to tumour challenge after tumour laser thermotherapy is associated with a cellular immune response.

Previous studies in our laboratory have shown that interstitial laser thermotherapy (ILT) of an experimental liver tumour is superior to surgical excision, at least partly due to a laser-induced immunological effect. The aim of the present study was to investigate the time-response relationship of the ILT-induced immunisation and the cellular response of macrophages and lymphocytes. A dimethylhydrazine-induced adenocarcinoma was transplanted into the liver of syngeneic rats. Rats with tumour were treated 6-8 days later (tumour size 0.25-0.40 cm(3)) with ILT of tumour or resection of the tumour-bearing lobe. Two groups of rats without tumour were treated with resection of a normal liver lobe or ILT of normal liver. A challenging tumour was implanted into the liver of each rat 2, 5 or 10 weeks after primary treatment. Rats were killed 6, 12 and 48 days (or earlier due to their condition) after challenge (n = 8 in all groups). Immunohistochemical techniques were used to determine lymphocytes (CD8, CD4) and macrophages (ED1, ED2) in rats having had treatment of a primary tumour. Interstitial laser thermotherapy of the first tumour was followed by eradication of challenging tumour and absence of tumour spread. This contrasted with rapid growth and spread of challenging tumour in the other groups. In the challenging vital tumour tissue and in the interface between the tumour and surroundings, the number of ED1 macrophages and CD8 lymphocytes was higher in rats having been treated with the ILT of tumour than in those having undergone resection of the tumour-bearing lobe. The number of ED2 macrophages and CD4 lymphocytes was low and did not vary between these two groups. Interstitial laser thermotherapy elicited an immune response that eradicated a challenging tumour and was associated with increased numbers of tumour-infiltrating macrophages and CD8 lymphocytes.

Dietary dehydroepiandrosterone inhibits bone marrow and leukemia cell transplants: role of food restriction.

Dietary dehydroepiandrosterone (DHEA) inhibits the proliferation of syngeneic bone marrow cells (BMC) infused into lethally irradiated mice. Potential mechanisms for suppression of hematopoiesis were evaluated and the findings were as follows: (i) depletion of NK, T, B or macrophage cells failed to reverse suppression by DHEA; (ii) stem cell stimulation by erythropoietin, growth hormone, interleukin-2, Friend leukemia virus, or cyclophosphamide failed to reverse suppression; (iii) supplementation of fatty acids, mevalonate, or deoxyribonucleotides, which are dependent upon glucose-6-phosphate dehydrogenase function, did not enhance BMC growth in mice fed DHEA; (iv) DHEA downstream metabolites 4-androstenedione and 17beta-estradiol, as well as the synthetic steroid, 16alpha-chloroepiandrosterone (but not testosterone or 5-androstene-3beta,17beta-diol), also inhibited BMC growth. Tamoxifen antagonized the effects of 17beta-estradiol but not DHEA; (v) dietary DHEA causes hypothermia, but housing of DHEA-fed mice at 34 degrees C to maintain normal body temperature did not reverse suppression; (vi) DHEA leads to a decrease in food intake in rodents. Pair-feeding control diet to mice fed DHEA mimicked the effects of dietary DHEA; (vii) adrenalectomy and orchiectomy decrease the levels of stress and sex hormones, respectively. Neither procedure affected the ability of food restriction or DHEA feeding to inhibit hematopoiesis; (viii) growth of GR-3 NM pre-B leukemia cells in unirradiated mice was also suppressed by DHEA or food restriction. We conclude that DHEA, by reducing food intake in mice, inhibits bone marrow and leukemia cell growth. The precise mechanism(s) by which reduced food intake per se inhibits hematopoiesis is not known, but may involve an increased rate of cellular apoptosis.

Immunomodulation by water-soluble derivative of propolis: a factor of antitumor reactivity.

The antimetastatic efficacy of a water-soluble derivative of propolis (WSDP) was studied. Tumor was a transplantable mammary carcinoma of CBA mouse. Metastases in the lung were generated by 2 x 10(5) viable tumor cells i.v. WSDP was given intraperitoneally at doses of 50 or 150 mg/kg before or after tumor cell inoculation. Therapies reduced the number of metastases in the lung and tumor growth was suppressed significantly by WSDP. It is likely that antimetastatic activity of the WSDP is mainly mediated by immunomodulatory activity. Changes in several immunological parameters such as production of lymphocyte activating factor by peritoneal macrophages and the efficacy of those macrophages to kill tumor cell in vitro, responses of lymphocytes to mitogen, and weight and cellularity of spleen, respectively, correlated well with antimetastatic properties of the WSDP. Based on results we postulate that the antimetastatic activity of propolis includes a pronounced immunomodulatory activity mainly toward augmentation of nonspecific antitumor resistance in mice via macrophage activation.

Loss of natural killer cell activity after murine tumor transplantation appears as a consequence of dietary lipid administration.

It is generally assumed that unsaturated fatty acids are important biological mediators that may be applied in the treatment of patients suffering from autoimmune disorders, in the modulation of tumorigenic processes or in the induction or inhibition of apoptosis. In this study, mice divided into three groups were fed dietary lipids; olive oil (20% w/w), fish oil (20% w/w) or hydrogenated coconut oil (20% w/w) for four weeks. Then, survival percentage, natural killer (NK) cell activity and lipid peroxidation were measured after murine lymphoma (LSTRA) transplantation. Survival percentage showed a reduced resistance to LSTRA tumor in mice fed fish oil diet and generaly loss of NK cell activity was observed after lymphoma transplantation. Lipid peroxidation from mice fed dietary lipids was measured in the presence of both phospholipase and cyclooxygenase inhibitors. In general, the data contained in this paper point to a detrimental effect caused by dietary lipids in mice transplanted with a lymphoma.

Mutated mitogen-activated protein kinase: a tumor rejection antigen of mouse sarcoma.

The molecular basis of the polymorphic tumor rejection antigens of chemically induced sarcomas of inbred mice remains a mystery, despite the discovery of these antigens over 40 years ago and their critical importance to the foundation of tumor immunology. In an analysis of a panel of BALB/c 3-methylcholanthrene-induced tumors, we identified one tumor, CMS5, that elicited a strong cytotoxic T cell response with exquisite specificity for CMS5. A stable cloned line of T cells with this specificity (C18) was used to screen a CMS5 cDNA expression library. The gene encoding the C18-defined antigen was identified as a mutated form of a mouse mitogen-activated protein kinase, ERK2, and a peptide incorporating the resulting amino acid substitution (lysine to glutamine) was efficiently recognized by C18. Vaccination with this peptide elicited specific resistance to CMS5 challenge. Extensive efforts to isolate antigen-loss variants of CMS5 were unsuccessful, suggesting that the mutated mitogen-activated protein kinase is essential for maintenance of the malignant phenotype.

Prevention of lethal graft-versus-host disease following allogeneic bone marrow transplantation in mice by short course administration of LF 08-0299.

We investigated the ability of LF 08--0299, a new immunosuppressive compound, to prevent murine graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT). A short term LF 08--0299 treatment at optimal dosage protected more than 75% of recipient mice from lethal GVHD induced either across minor antigens alone or the full H2 barrier. Furthermore, LF 08--0299 still prevented lethal GVHD when treatment was delayed to 10 days post-BMT. Long-term LF 08--0299-treated survivors were free of clinical signs of GVHD, and histopathologic examination of liver, skin, and intestines was normal, demonstrating that recipient mice did not develop chronic GVHD. We assessed the immunocompetence of long-term surviving recipient mice. Results from MLR and CTL assays were weak whereas responses against unrelated H2 antigens were reduced but still preserved. Moreover, in vivo transfer experiments demonstrated that spleen cells from long-term survivors were unable to induce lethal GVHD in irradiated recipients of host origin, while spleen cells injected in irradiated recipients of a host-unrelated H2 were fully competent to induce a lethal GVHD. Together these results indicate that stable chimeric recipient mice were specifically tolerant to host antigens. We further showed that while LF 08--0299 can protect recipient mice from lethal GVHD, it also preserved a graft-versus-leukemia effect when mice were inoculated with P815 tumor cells. These data suggest that LF 08--0299 may be a novel pharmaceutical agent that would prevent GVHD in human unrelated bone marrow transplantation.