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 cytokines has been demonstrated both in vitro and in vivo, whereas the cellular and molecular changes in prostate carcinoma properties after cytokine treatment have never been characterized. We have thus investigated whether the intrinsic properties of prostate carcinoma cells that are associated with tumor development and progression can be altered by direct cytokine treatment. METHODS LNCaP, DU‐145, and PC‐3 cell lines were treated with tumor necrosis factor‐alpha (TNF‐α) (200 U/mL), interferon‐gamma (IFN‐γ) (500 U/mL), human leukocyte interferon (IFN‐α) (500 U/mL), and interleukin‐2 (IL‐2) (400 U/mL). The expression of (prostate‐specific antigen [PSA] and prostate‐specific membrane [PSM]), androgen receptor (AR), growth factors, oncogenes, collagenase, cell adhesion molecules, HLA antigens, cell adhesion to human bone marrow stroma, and cell growth were determined by quantitative polymerase chain reaction (PCR) analysis, fluorescence‐activated cell sorter (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 treatment did not alter PSM mRNA expression, whereas a 15‐fold decrease in PSA and a 5‐fold reduction in AR mRNA expression was detected in TNF‐α‐treated cells. The down regulation of PSA production was also demonstrated at the protein level in a dose‐dependent fashion. A fivefold decrease in PSA mRNA expression was also detected in IL‐2‐treated LNCaP cells but without a reduction in AR. Down regulated epidermal growth factor receptor (EGF‐R) and basic fibroblast growth factor (b‐FGF) mRNA expressions were detected in TNF‐α‐ and IFN‐α‐treated DU‐145 and PC‐3 cells, whereas, only reduced EGF‐R expression was observed in LNCaP cells. IFN‐γ and IL‐2 treatment down regulated the expression of collagenase Type IV mRNA in DU‐145 and PC‐3 cells, whereas tumor transforming growth factor‐β (TGF‐β) and IL‐6 mRNA expressions did not exhibit any essential changes after cytokine treatment. A reduction in c‐myc mRNA expression was observed in TNF‐α‐ and IFN‐α‐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‐α‐ and IFN‐γ‐treated PC‐3 cells. FACS analysis revealed t