Evidence that androgen-independent stromal growth factor signals promote androgen-insensitive prostate cancer cell growth in vivo

Abstract

Activation of tumor-stromal interactions is considered to play a critical role in the promotion of tumorigenesis. To discover new therapeutic targets for hormone-refractory prostate tumor growth under androgen ablation therapy, androgen-sensitive LNCaP cells and the derived sublines, E9 (androgen-low-sensitive), and AIDL (androgen-insensitive), were recombined with androgendependent embryonic rat urogenital sinus mesenchyme (UGM). Tumors of E9CUGM and AIDLCUGM were approximately three times as large as those of LNCaPCUGM. Tumors grown in castrated hosts exhibited reduced growth as compared with those in intact hosts. However, in castrated hosts, E9CUGM and AIDLCUGM tumors were still approximately twice as large as those of LNCaPCUGM. Cell proliferation in tumors of E9CUGM and AIDLCUGM grown in castrated host, was significantly higher than that in tumors of LNCaPCUGM. In vitro, expression of fibroblast growth factor (FGF)-2 and IGF-I, but not FGF-7 mRNA, was significantly reduced in UGM under androgen starvation. In cell culture, E9 cells were responsive to FGF-2 and FGF-7 stimulation, while AIDL responded to FGF-7 and IGF-1. Expression of FGFR1 and FGFR2 was considerably higher in E9 than those in LNCaP, similarly expression of FGFR2 and IGF-IR were elevated in AIDL. These data suggest that activation of prostate cancer cell growth through growth factor receptor expression may result in the activity of otherwise androgenindependent stromal growth factor signals such as FGF-7 under conditions of androgen ablation.

Naftopidil, a Selective α1-Adrenoceptor Antagonist, Suppresses Human Prostate Tumor Growth by Altering Interactions between Tumor Cells and Stroma

“…AIDL cells were cultured in phenol red-free RPMI-1640 supplemented with 10% charcoal-stripped (CS) FBS and 1% antibiotic/antimycotic solution. The parental LNCaP, E9, and AIDL lines expressed similar levels of androgen receptor in culture, but prostate-specific antigen (PSA) protein was detected only in parental LNCaP cells (19). The androgen sensitivity of parental LNCaP, E9, and AIDL was confirmed by the change of PSA mRNA expression in cell culture with synthetic androgen R1881 (19).…”

“…The parental LNCaP, E9, and AIDL lines expressed similar levels of androgen receptor in culture, but prostate-specific antigen (PSA) protein was detected only in parental LNCaP cells (19). The androgen sensitivity of parental LNCaP, E9, and AIDL was confirmed by the change of PSA mRNA expression in cell culture with synthetic androgen R1881 (19). Human prostate stromal cell PrSC was purchased from Lonza Group Ltd. PrSC was maintained using SCGM Bullet Kit (Lonza Group Ltd) as recommended.…”

“…Immunohistochemical (IHC) staining was performed with a Vectastain ABC elite kit (Vector Laboratories Inc) following our previously reported protocols (19). The extent of Ki-67 labeling was expressed as the percentage of positive nuclear cells.…”

Fibroblasts prolong serum prostate-specific antigen decline after androgen deprivation therapy in prostate cancer

“…Extracted protein was separated by gel electrophoresis and transferred to Immobilon polyvinylidene difluoride membranes following our previously reported protocol. 17 Co-Culture of Prostate Epithelial Cell Lines (LNCaP, 22Rv1, and RWPE-1) with Fibroblasts LNCaP, 22Rv1, and RWPE-1 cells were co-cultured with each of the four fibroblast lines (PrSC, pcPrF-M5, pcPrF-M6, and pcPrF-M7) in six-well plates using cell culture inserts (BD Falcon, Franklin Lakes, NJ, USA). LNCaP, 22Rv1, and RWPE-1 cells (4 × 10 4 cells/well) were seeded into six-well plates in their respective recommended medium, while fibroblasts (PrSC, pcPrF-M5, pcPrF-M6, and pcPrF-M7; 2 × 10 4 cells/well) were seeded in SCBM media into cell culture inserts for 2 days.…”

“…16 Several studies have reported that androgen-sensitive and -insensitive interactions between stromal and epithelial cells determine how prostate epithelial cells respond to androgen ablation. 17,18 In a low-androgen environment, stromal-epithelial interactions may be an important mechanism controlling AR activity and AR-regulated PSA expression.…”