IN-VITRO MODULATION OF TUMOR PROGRESSION-ASSOCIATED PROPERTIES OF HORMONE-REFRACTORY PROSTATE CARCINOMA CELL-LINES BY CYTOKINES

BACKGROUND, Cytokines exert cytostatic and immunomodulatory effects on carcinoma cells. Growth inhibition of human prostate carcinoma by cyt okines has been demonstrated both in vitro and in vivo, whereas the ce llular and molecular changes in prostate carcinoma properties after cy tokine treatment have never been characterized. We have thus investiga ted whether the intrinsic properties of prostate carcinoma cells that are associated with tumor development and progression can be altered b y direct cytokine treatment. METHODS, LNCaP, DU-145, and PC-3 cell lin es were treated with tumor necrosis factor-alpha (TNF-alpha) (200 U/mL ), interferon-gamma (IFN-gamma) (500 U/mL), human leukocyte interferon (IFN-alpha) (500 U/mL), and interleukin-2 (IL-2) (400 U/mL). The expr ession of (prostate-specific antigen [PSA] and prostate-specific membr ane [PSM]), androgen receptor (AR), growth factors, oncogenes, collage nase, cell adhesion molecules, HLA, antigens, cell adhesion to human b one marrow stroma, and cell growth were determined by quantitative pol ymerase chain reaction (PCR) analysis, fluorescence-activated cell sor ter (FACS) analysis, and cell attachment and proliferation assays, and were compared with nontreated cells. RESULTS, PCR analysis indicated that only LNCaP cells expressed PSA, PSM, and AR mRNA. Cytokine treatm ent did not alter PSM mRNA expression, whereas a 15-fold decrease in P SA and a 5-fold reduction in AR mRNA expression was detected in TNF-cu -treated cells. The down regulation of PSA production was also demonst rated at the protein level in a dose-dependent fashion. A fivefold dec rease in PSA mRNA expression was also detected in IL-2-treated LNCaP c ells but without a reduction in AR. Down regulated epidermal growth fa ctor receptor (EGF-R) and basic fibroblast growth factor (b-FGF) mRNA expressions were detected in TNF-alpha- and IFN-alpha-treated DU-145 a nd PC-3 cells, whereas, only reduced EGF-R expression was observed in LNCaP cells. lFN-gamma and IL-2 treatment down regulated the expressio n of collagenase Type IV mRNA in DU-145 and PC-3 cells, whereas tumor transforming growth factor-beta (TGF-beta) and IL-6 mRNA expressions d id not exhibit any essential changes after cytokine treatment. A reduc tion in c-myc mRNA expression was observed in TNF-alpha- and IFN-alpha -treated cells, whereas no change in HER-2 expression was noted in any cytokine treated cells. Up regulated P-cadherin, but not E-cadherin, mRNA expression was detected in TNF-alpha- and IFN-gamma-treated PC-3 cells. FAGS analysis revealed that all but IL-2-treated cells had enha nced HLA Class I expression, with the maximum effect seen in TNF-alpha -treated LNCaP cells (threefold increase). Up regulated HLA Class II e xpression was seen only in IFN-gamma-treated cells. All cytokine-treat ed DU-145 and PC-3 cells expressed reduced levels of alpha 3, but not beta 1, integrin. Up regulation of ICAM-1 expression was seen in all c ytokine treated DU-145 and PC-3 cells, whereas no change in CD44 occur red. Cytokine treatment reduced the binding affinity of LNCaP and DU-1 45, but not of PC-3 cells, to human bone marrow stromal cells, and all cytokines but IL-2 showed a mild to moderate growth inhibition to pro state cancer cells, with a marked inhibition only observed in TNF-alph a-treated LNCaP cells. CONCLUSIONS. Cytokine treatment can effectively alter several prostate carcinoma properties that are closely associat ed with tumor invasion and a metastatic phenotype, suggesting that imm unotherapy via the local delivery of cytokines may have a potentially therapeutic role in the treatment of hormone-refractory prostate cance r through both direct and indirect antitumor mechanisms.