PubMed · 8424989
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J M Goust, H Stevenson, R Galbraith, G Virella. 1993. Immunosuppression and immunomodulation.. https://pubmed.ncbi.nlm.nih.gov/8424989/
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BACKGROUND: Melatonin, the main secretory product of the pineal gland, inhibits the growth of several types of cancer cells. Melatonin limits human prostate cancer cell growth by a mechanism which involves the regulation of androgen receptor function but it is not clear whether other mechanisms may also be involved. METHODS: Time-course and dose-dependent studies were performed using androgen-dependent (LNCaP) and independent (PC3) prostate cancer cells. Cell number, cell viability, and cell cycle progression were studied. Neuroendocrine differentiation of these cells was evaluated by studying morphological and biochemical markers. Finally, molecular mechanisms including the participation of melatonin membrane receptors, intracellular cAMP levels, and the PKA signal transduction pathway were also analyzed. RESULTS: Melatonin treatment dramatically reduced the number of prostate cancer cells and stopped cell cycle progression in both LNCaP and PC3 cells. In addition, it induced cellular differentiation as indicated by obvious morphological changes and neuroendocrine biochemical parameters. The role of melatonin in cellular proliferation and differentiation of prostate cancer cells is not mediated by its membrane receptors nor related to PKA activation. CONCLUSIONS: The treatment of prostate cancer cells with pharmacological concentrations of melatonin influences not only androgen-sensitive but also androgen-insensitive epithelial prostate cancer cells. Cell differentiation promoted by melatonin is not mediated by PKA activation although it increases, in a transitory manner, intracellular cAMP levels. Melatonin markedly influences the proliferative status of prostate cancer cells. These effects should be evaluated thoroughly since melatonin levels are diminished in aged individuals when prostate cancer typically occurs.
BACKGROUND: Prostate cancer is the most common malignancy in Swedish and American men. Effective curative treatment modalities are debilitating and available only for localized disease. As an immunotherapy approach, DNA encoding prostate-specific antigen (PSA), was used to immunize mice and induce PSA-specific cellular immunity. METHODS: A plasmid expressing PSA, alone or in combination with plasmids coding for GM-CSF and/or IL-2, was used for DNA immunization. Cr-release, intracellular IFN-gamma cytokine staining, and tumor challenge assays were used to evaluate the immune response. RESULTS: The DNA vaccine induces PSA-specific cytotoxic T lymphocytes (CTLs) and when co-injected with IL-2 and GM-CSF it protects four of five mice against a PSA-expressing tumor challenge. CONCLUSIONS: We demonstrate that immunization with a PSA DNA vaccine can evoke PSA-specific cellular immune responses. We also show, for the first time, that a PSA DNA vaccine can induce anti-tumor immunity in vivo.
Diesel exhaust particles, and polystyrene particles (PSP) as a model for the insoluble particle core, have an adjuvant effect on allergen-specific IgE production in mice. We therefore examined the primary immune response in the draining popliteal lymph node (PLN) to the allergen ovalbumin (OVA) injected together with polystyrene particles into the footpad of BALB/cA mice. Similar numbers of particle-containing cells were observed in the draining lymph node on day 1 after injection of PSP alone or OVA + PSP, the numbers increasing continuously until day 21. The total lymph node cell numbers increased three to four times in the OVA + PSP group compared to both OVA and PSP groups, peaking on day 5. The increase in B cell numbers was twice the increase in T cell numbers. On day 5, OVA + PSP increased the expression of most surface markers measured (MHC class II, CD86, CD23, CD69) compared to OVA and PSP. Further, the ex vivo production of IL-4 and IL-10 by PLN cells from OVA + PSP-injected animals was increased. In conclusion, whereas PSP alone did not influence any of the immunologic markers studied, the adjuvant effect of PSP on the IgE antibody response to OVA was associated with an early increased primary cellular response in the draining lymph node.