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Overexpression of FGF9 in prostate epithelial cells augments reactive stroma formation and promotes prostate cancer progression.

Huang Y, Jin C, Hamana T, Liu J, Wang C, An L, McKeehan WL, Wang F - Int. J. Biol. Sci. (2015)

Bottom Line: Both in vivo and in vitro data indicated that FGF9 promoted TGFβ1 expression via increasing cJun-mediated signaling.Moreover, in silico analyses showed that the expression level of FGF9 was positively associated with expression of TGFβ1 and its downstream signaling molecules in human prostate cancers.Collectively, our data demonstrated that overexpressing FGF9 in PCa cells augmented the formation of reactive stroma and promoted PCa initiation and progression.

View Article: PubMed Central - PubMed

Affiliation: 1. Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA.

ABSTRACT
Bone metastasis is the major cause of morbidity and mortality of prostate cancer (PCa). Fibroblast growth factor 9 (FGF9) has been reported to promote PCa bone metastasis. However, the mechanism by which overexpression of FGF9 promotes PCa progression and metastasis is still unknown. Herein, we report that transgenic mice forced to express FGF9 in prostate epithelial cells (F9TG) developed high grade prostatic intraepithelial neoplasia (PIN) in an expression level- and time-dependent manner. Moreover, FGF9/TRAMP bigenic mice (F9TRAMP) grew advanced PCa earlier and had higher frequencies of metastasis than TRAMP littermates. We observed tumor microenvironmental changes including hypercellularity and hyperproliferation in the stromal compartment of F9TG and F9TRAMP mice. Expression of TGFβ1, a key signaling molecule overexpressed in reactive stroma, was increased in F9TG and F9TRAMP prostates. Both in vivo and in vitro data indicated that FGF9 promoted TGFβ1 expression via increasing cJun-mediated signaling. Moreover, in silico analyses showed that the expression level of FGF9 was positively associated with expression of TGFβ1 and its downstream signaling molecules in human prostate cancers. Collectively, our data demonstrated that overexpressing FGF9 in PCa cells augmented the formation of reactive stroma and promoted PCa initiation and progression.

No MeSH data available.


Related in: MedlinePlus

Depletion of FGF9 suppresses tumorigenicity of TRAMP tumor cells. A. Real-time RT-PCR analyses for Fgf9 expression in TRAMP-C2 cells and FGF9 depleted TRAMP-C2 cells. B. Subcutaneous grafts of TRAMP-C2/UGM cells with or without FGF9 depletion in TRAMP-C2 cells. Graft weight is mean ± sd from 3 grafts per group. C. H&E and immunostaining of graft sections with the indicated antibodies. D. Masson Trichrome staining of prostate sections of 64-month-old TRAMP or F9TRAMP mice, demonstrating excessive collagen deposition in the stromal compartment of F9TRAMP mice. E. Co-staining of α-smooth muscle actin and vimentin in 4-month-old TRAMP and F9TRAMP prostates. UGM, urogenital mesenchymal cells; Ctrl, control; KD, knockdown; scale bar, 50 µm.
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Figure 5: Depletion of FGF9 suppresses tumorigenicity of TRAMP tumor cells. A. Real-time RT-PCR analyses for Fgf9 expression in TRAMP-C2 cells and FGF9 depleted TRAMP-C2 cells. B. Subcutaneous grafts of TRAMP-C2/UGM cells with or without FGF9 depletion in TRAMP-C2 cells. Graft weight is mean ± sd from 3 grafts per group. C. H&E and immunostaining of graft sections with the indicated antibodies. D. Masson Trichrome staining of prostate sections of 64-month-old TRAMP or F9TRAMP mice, demonstrating excessive collagen deposition in the stromal compartment of F9TRAMP mice. E. Co-staining of α-smooth muscle actin and vimentin in 4-month-old TRAMP and F9TRAMP prostates. UGM, urogenital mesenchymal cells; Ctrl, control; KD, knockdown; scale bar, 50 µm.

Mentions: TRAMP-C2 cells are derived from TRAMP tumors and express Fgf9 at a moderate level. To further characterize the role of FGF9 in prostate tumorigenesis, expression of Fgf9 in TRAMP-C2 cells was depleted by infecting the cells with lentivirus bearing shRNA specific for Fgf9 mRNA (Fig. 5A). The cells were then mixed with mouse urogenital sinus mesenchymal cells and grafted in the flanks of nude mice. Eight weeks after the implantation, tumor grafts were excised for analysis. The graft size of the FGF9 depleted cells was smaller than that of the control cells (Fig. 5B). Although no significant difference in general histology between the two groups was detected (Fig. 5C a,b), depletion of FGF9 compromised cell proliferation in the graft (Fig. 5Cc,d). In addition, the FGF9-depleted grafts had fewer endothelial cells that are CD31 positive than the control group, indicating compromised angiogenesis in the FGF9 depleted graft (Fig. 5Ce,f). This is in agreement with a previous report that FGF9 induces VEGF-A expression in PCa 43. Interestingly, immunostaining with anti-F4/80 antibodies revealed that depletion of FGF9 reduced macrophage infiltration in TRAMP-C2 grafts (Fig. 5Cg,h), implying a role of epithelial-expressed FGF9 in reactive stroma formation and microenvironmental remodeling. Trichrome staining revealed that the stroma of F9TRAMP prostates exhibited extensive collagen deposition, which is indicative of reactive stroma (Fig. 5D). In addition, the well-organized smooth muscle layer surrounding the epithelial cells became fragmented with increased vimentin-positive fibroblast-like cells (Fig. 5E). Consistently, the F9TG prostates also exhibited a disrupted stromal compartment (Fig. 2Ff). Together, the results indicate that overexpression of FGF9 promotes growth and metastasis of PCa, in part by remodeling tumor microenvironment.


Overexpression of FGF9 in prostate epithelial cells augments reactive stroma formation and promotes prostate cancer progression.

Huang Y, Jin C, Hamana T, Liu J, Wang C, An L, McKeehan WL, Wang F - Int. J. Biol. Sci. (2015)

Depletion of FGF9 suppresses tumorigenicity of TRAMP tumor cells. A. Real-time RT-PCR analyses for Fgf9 expression in TRAMP-C2 cells and FGF9 depleted TRAMP-C2 cells. B. Subcutaneous grafts of TRAMP-C2/UGM cells with or without FGF9 depletion in TRAMP-C2 cells. Graft weight is mean ± sd from 3 grafts per group. C. H&E and immunostaining of graft sections with the indicated antibodies. D. Masson Trichrome staining of prostate sections of 64-month-old TRAMP or F9TRAMP mice, demonstrating excessive collagen deposition in the stromal compartment of F9TRAMP mice. E. Co-staining of α-smooth muscle actin and vimentin in 4-month-old TRAMP and F9TRAMP prostates. UGM, urogenital mesenchymal cells; Ctrl, control; KD, knockdown; scale bar, 50 µm.
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Figure 5: Depletion of FGF9 suppresses tumorigenicity of TRAMP tumor cells. A. Real-time RT-PCR analyses for Fgf9 expression in TRAMP-C2 cells and FGF9 depleted TRAMP-C2 cells. B. Subcutaneous grafts of TRAMP-C2/UGM cells with or without FGF9 depletion in TRAMP-C2 cells. Graft weight is mean ± sd from 3 grafts per group. C. H&E and immunostaining of graft sections with the indicated antibodies. D. Masson Trichrome staining of prostate sections of 64-month-old TRAMP or F9TRAMP mice, demonstrating excessive collagen deposition in the stromal compartment of F9TRAMP mice. E. Co-staining of α-smooth muscle actin and vimentin in 4-month-old TRAMP and F9TRAMP prostates. UGM, urogenital mesenchymal cells; Ctrl, control; KD, knockdown; scale bar, 50 µm.
Mentions: TRAMP-C2 cells are derived from TRAMP tumors and express Fgf9 at a moderate level. To further characterize the role of FGF9 in prostate tumorigenesis, expression of Fgf9 in TRAMP-C2 cells was depleted by infecting the cells with lentivirus bearing shRNA specific for Fgf9 mRNA (Fig. 5A). The cells were then mixed with mouse urogenital sinus mesenchymal cells and grafted in the flanks of nude mice. Eight weeks after the implantation, tumor grafts were excised for analysis. The graft size of the FGF9 depleted cells was smaller than that of the control cells (Fig. 5B). Although no significant difference in general histology between the two groups was detected (Fig. 5C a,b), depletion of FGF9 compromised cell proliferation in the graft (Fig. 5Cc,d). In addition, the FGF9-depleted grafts had fewer endothelial cells that are CD31 positive than the control group, indicating compromised angiogenesis in the FGF9 depleted graft (Fig. 5Ce,f). This is in agreement with a previous report that FGF9 induces VEGF-A expression in PCa 43. Interestingly, immunostaining with anti-F4/80 antibodies revealed that depletion of FGF9 reduced macrophage infiltration in TRAMP-C2 grafts (Fig. 5Cg,h), implying a role of epithelial-expressed FGF9 in reactive stroma formation and microenvironmental remodeling. Trichrome staining revealed that the stroma of F9TRAMP prostates exhibited extensive collagen deposition, which is indicative of reactive stroma (Fig. 5D). In addition, the well-organized smooth muscle layer surrounding the epithelial cells became fragmented with increased vimentin-positive fibroblast-like cells (Fig. 5E). Consistently, the F9TG prostates also exhibited a disrupted stromal compartment (Fig. 2Ff). Together, the results indicate that overexpression of FGF9 promotes growth and metastasis of PCa, in part by remodeling tumor microenvironment.

Bottom Line: Both in vivo and in vitro data indicated that FGF9 promoted TGFβ1 expression via increasing cJun-mediated signaling.Moreover, in silico analyses showed that the expression level of FGF9 was positively associated with expression of TGFβ1 and its downstream signaling molecules in human prostate cancers.Collectively, our data demonstrated that overexpressing FGF9 in PCa cells augmented the formation of reactive stroma and promoted PCa initiation and progression.

View Article: PubMed Central - PubMed

Affiliation: 1. Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA.

ABSTRACT
Bone metastasis is the major cause of morbidity and mortality of prostate cancer (PCa). Fibroblast growth factor 9 (FGF9) has been reported to promote PCa bone metastasis. However, the mechanism by which overexpression of FGF9 promotes PCa progression and metastasis is still unknown. Herein, we report that transgenic mice forced to express FGF9 in prostate epithelial cells (F9TG) developed high grade prostatic intraepithelial neoplasia (PIN) in an expression level- and time-dependent manner. Moreover, FGF9/TRAMP bigenic mice (F9TRAMP) grew advanced PCa earlier and had higher frequencies of metastasis than TRAMP littermates. We observed tumor microenvironmental changes including hypercellularity and hyperproliferation in the stromal compartment of F9TG and F9TRAMP mice. Expression of TGFβ1, a key signaling molecule overexpressed in reactive stroma, was increased in F9TG and F9TRAMP prostates. Both in vivo and in vitro data indicated that FGF9 promoted TGFβ1 expression via increasing cJun-mediated signaling. Moreover, in silico analyses showed that the expression level of FGF9 was positively associated with expression of TGFβ1 and its downstream signaling molecules in human prostate cancers. Collectively, our data demonstrated that overexpressing FGF9 in PCa cells augmented the formation of reactive stroma and promoted PCa initiation and progression.

No MeSH data available.


Related in: MedlinePlus