A recent clinical vaccine trial to treat early breast cancer prior to surgery induced strong immune response characterized by production of Th1 cytokines including Interferon-gamma (IFN-γ). Of 27 vaccinated subjects, 5 showed complete regression of tumor by the time of surgery. In vitro studies indicated that Th1 cytokine production might have a direct killing effect on breast cancer cells. We therefore sought to determine whether other carcinoma types were also sensitive to Th1 cytokines, a fact that might indicate their sensitivity to similar therapeutic vaccination. We therefore examined the effects of the two principal Th1 cytokines, IFN-γ and TNF-α on 3 common prostate cancer cell lines including LnCap, PC3 and DU145. Several techniques were used to measure apoptotic behavior, which included Alamar Blue dye, microscopic observation, vital staining, and Flow cytometry analysis. Obtaining decent apoptotic responses in each cell line to the cytokines, enhancing the effects of an anti-cancer drug, Alisertib, was then examined. Each cell line was incubated in tissue culture with cytokines only, Alisertib only, and both combined for up to 5 days. Addition of the Alamar Blue dye during the last hours of culture indicated that the cocktail of cytokines and Alisertib-treated cells displayed sharply reduced metabolic activity. Likewise, microscopic observation of cells indicated signs of cell death. Vital staining indicated less viable cells in Th1 cytokine + Alisertib-treated groups compared to untreated controls and cytokines alone. Finally, Flow cytometry analysis of cytokine treated cells showed evidence of enhanced apoptosis compared with untreated cells and cytokine-treated cells alone, indicated by a greater population of cells being induced to programmed cell death in cytokine and Alisertib-treated cells. Thus, treatment involving the combined applications of apoptosis and immunologic enhancers provides new insight into the treatment of prostate cancer.
Gary Koski Ph.D
Lori Showalter Ph.D
Early breast cancer vaccine therapy may be mediated, in part, through the action of T cell-secreted cytokines Interferon-gamma (IFN-γ) and Tumor necrosis factor alpha (TNF-α). We then sought to determine if three types of prostate cancers (LnCap, PC3, and DU145) showed similar susceptibility to these cytokines and if the addition of the apoptosis-enhancing agent, Alisertib, would further enhance these effects. There was impaired metabolic activity, fewer viable cells and apoptotic cell death induced by cytokines with Alisertib, as compared to cytokines alone. These studies indicate that vaccines stimulating production of cytokines may be effective for prostate cancer, and are enhanced by Alisertib.