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FGFR3 has tumor suppressor properties in cells with epithelial phenotype.

Lafitte M, Moranvillier I, Garcia S, Peuchant E, Iovanna J, Rousseau B, Dubus P, Guyonnet-Dupérat V, Belleannée G, Ramos J, Bedel A, de Verneuil H, Moreau-Gaudry F, Dabernat S - Mol. Cancer (2013)

Bottom Line: The receptor exerted dual effects: it suppressed tumor growth in pancreatic epithelial-like cells and had oncogenic properties in pancreatic mesenchymal-like cells.Both FGFR3 splice variants had similar effects and used the same intracellular signaling.TKIs against FGFR3 might result in adverse effects if used in the wrong cell context.

View Article: PubMed Central - HTML - PubMed

Affiliation: INSERM U1035, Université Bordeaux Segalen, 146 rue Léo Saignat, Bordeaux 33076, France.

ABSTRACT

Background: Due to frequent mutations in certain cancers, FGFR3 gene is considered as an oncogene. However, in some normal tissues, FGFR3 can limit cell growth and promote cell differentiation. Thus, FGFR3 action appears paradoxical.

Results: FGFR3 expression was forced in pancreatic cell lines. The receptor exerted dual effects: it suppressed tumor growth in pancreatic epithelial-like cells and had oncogenic properties in pancreatic mesenchymal-like cells. Distinct exclusive pathways were activated, STATs in epithelial-like cells and MAP Kinases in mesenchymal-like cells. Both FGFR3 splice variants had similar effects and used the same intracellular signaling. In human pancreatic carcinoma tissues, levels of FGFR3 dropped in tumors.

Conclusion: In tumors from epithelial origin, FGFR3 signal can limit tumor growth, explaining why the 4p16.3 locus bearing FGFR3 is frequently lost and why activating mutations of FGFR3 in benign or low grade tumors of epithelial origin are associated with good prognosis. The new hypothesis that FGFR3 can harbor both tumor suppressive and oncogenic properties is crucial in the context of targeted therapies involving specific tyrosine kinase inhibitors (TKIs). TKIs against FGFR3 might result in adverse effects if used in the wrong cell context.

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FGFR3 has tumor suppressor gene properties in BxPC-3 and Capan-2 pancreatic cell lines. A) Capan-2 cells were transduced with either control (a,d), FGFR3-IIIb (b,e) or FGFR3-IIIc ZsGreen lentivectors (c,f) and observed with a fluorescence microscope (original magnification ×40, bright field, a,b,c, green fluorescence, d,e,). Colonies with strong overexpression of either FGFR3-IIIb or –IIIc were smaller (arrows heads, b, c, e, f) than colonies with lower expression (arrows). Right panel: mean fluorescence intensity was determined for colonies transduced with the same lentivectors as in left panel, and were also transduced with a lentivector carrying a FGFR3-IIIc cDNA with the K508M mutation inactivating the kinase domain. B) FGFR3-IIIb and –IIIc overexpression decreased Capan-2 and BxPC-3 cell proliferation and (C) increased apoptosis. (D) FGFR3 forced expression had opposite effect on cell proliferation of Mia PaCa-2 and PANC-1 cells. NS: nor significant, *p = 0.05, **p < 0.01, ***p < 0.001.
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Figure 1: FGFR3 has tumor suppressor gene properties in BxPC-3 and Capan-2 pancreatic cell lines. A) Capan-2 cells were transduced with either control (a,d), FGFR3-IIIb (b,e) or FGFR3-IIIc ZsGreen lentivectors (c,f) and observed with a fluorescence microscope (original magnification ×40, bright field, a,b,c, green fluorescence, d,e,). Colonies with strong overexpression of either FGFR3-IIIb or –IIIc were smaller (arrows heads, b, c, e, f) than colonies with lower expression (arrows). Right panel: mean fluorescence intensity was determined for colonies transduced with the same lentivectors as in left panel, and were also transduced with a lentivector carrying a FGFR3-IIIc cDNA with the K508M mutation inactivating the kinase domain. B) FGFR3-IIIb and –IIIc overexpression decreased Capan-2 and BxPC-3 cell proliferation and (C) increased apoptosis. (D) FGFR3 forced expression had opposite effect on cell proliferation of Mia PaCa-2 and PANC-1 cells. NS: nor significant, *p = 0.05, **p < 0.01, ***p < 0.001.

Mentions: FGFR3 is expressed as two splice variants, the FGFR3-IIIb and FGFR3-IIIc. Forced expression of either splice variants was performed in two pancreatic ductal adenocarcinoma (PDAC) cell lines: the Capan-2 and the BxPC-3 pancreatic cells. The capacities of the cells to form clones in low density cultures was increased by both FGFR3-IIIb and IIIc as compared to the control condition, except for the IIIb splice variant in the BxPC-3 cells (Table 1). Interestingly, this effect was maintained when cells were transduced with a FGFR3-IIIc cDNA lacking tyrosine kinase activity (K508M mutation, FGFR3-IIIc-KD, Table 1). Interestingly however, the areas of the colonies were smaller with FGFR3 overexpression but not with FGFR3-IIIc-KD (Table 1). Noticeably, clones overexpressing high levels of FGFR3 appeared much smaller than clones expressing lower levels as attested by ZsGreen protein fluorescence intensity (Figure 1A, left panel). Mean fluorescence intensities were lower for cells transduced with active forms of FGFR3 (Figure 1A, right panel). Thus, FGFR3 promoted colony formation of pancreatic cells, but clone expansion was reduced. This latter effect depended on active FGFR3 tyrosine kinase. Furthermore, forced expression of both FGFR3 splice variants in Capan-2 and BxPC-3 cells reduced the cell proliferation (Figure 1B). Flow cytometry analyses did not evidence major differences in the distributions of cells in the cell cycles phases (Additional file 1: Figure S1), but a significant and important accumulation of cells in sub-G1 was observed, suggesting that FGFR3 induced apoptosis (Additional file 1: Figure S1 and Figure 1C).


FGFR3 has tumor suppressor properties in cells with epithelial phenotype.

Lafitte M, Moranvillier I, Garcia S, Peuchant E, Iovanna J, Rousseau B, Dubus P, Guyonnet-Dupérat V, Belleannée G, Ramos J, Bedel A, de Verneuil H, Moreau-Gaudry F, Dabernat S - Mol. Cancer (2013)

FGFR3 has tumor suppressor gene properties in BxPC-3 and Capan-2 pancreatic cell lines. A) Capan-2 cells were transduced with either control (a,d), FGFR3-IIIb (b,e) or FGFR3-IIIc ZsGreen lentivectors (c,f) and observed with a fluorescence microscope (original magnification ×40, bright field, a,b,c, green fluorescence, d,e,). Colonies with strong overexpression of either FGFR3-IIIb or –IIIc were smaller (arrows heads, b, c, e, f) than colonies with lower expression (arrows). Right panel: mean fluorescence intensity was determined for colonies transduced with the same lentivectors as in left panel, and were also transduced with a lentivector carrying a FGFR3-IIIc cDNA with the K508M mutation inactivating the kinase domain. B) FGFR3-IIIb and –IIIc overexpression decreased Capan-2 and BxPC-3 cell proliferation and (C) increased apoptosis. (D) FGFR3 forced expression had opposite effect on cell proliferation of Mia PaCa-2 and PANC-1 cells. NS: nor significant, *p = 0.05, **p < 0.01, ***p < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3750311&req=5

Figure 1: FGFR3 has tumor suppressor gene properties in BxPC-3 and Capan-2 pancreatic cell lines. A) Capan-2 cells were transduced with either control (a,d), FGFR3-IIIb (b,e) or FGFR3-IIIc ZsGreen lentivectors (c,f) and observed with a fluorescence microscope (original magnification ×40, bright field, a,b,c, green fluorescence, d,e,). Colonies with strong overexpression of either FGFR3-IIIb or –IIIc were smaller (arrows heads, b, c, e, f) than colonies with lower expression (arrows). Right panel: mean fluorescence intensity was determined for colonies transduced with the same lentivectors as in left panel, and were also transduced with a lentivector carrying a FGFR3-IIIc cDNA with the K508M mutation inactivating the kinase domain. B) FGFR3-IIIb and –IIIc overexpression decreased Capan-2 and BxPC-3 cell proliferation and (C) increased apoptosis. (D) FGFR3 forced expression had opposite effect on cell proliferation of Mia PaCa-2 and PANC-1 cells. NS: nor significant, *p = 0.05, **p < 0.01, ***p < 0.001.
Mentions: FGFR3 is expressed as two splice variants, the FGFR3-IIIb and FGFR3-IIIc. Forced expression of either splice variants was performed in two pancreatic ductal adenocarcinoma (PDAC) cell lines: the Capan-2 and the BxPC-3 pancreatic cells. The capacities of the cells to form clones in low density cultures was increased by both FGFR3-IIIb and IIIc as compared to the control condition, except for the IIIb splice variant in the BxPC-3 cells (Table 1). Interestingly, this effect was maintained when cells were transduced with a FGFR3-IIIc cDNA lacking tyrosine kinase activity (K508M mutation, FGFR3-IIIc-KD, Table 1). Interestingly however, the areas of the colonies were smaller with FGFR3 overexpression but not with FGFR3-IIIc-KD (Table 1). Noticeably, clones overexpressing high levels of FGFR3 appeared much smaller than clones expressing lower levels as attested by ZsGreen protein fluorescence intensity (Figure 1A, left panel). Mean fluorescence intensities were lower for cells transduced with active forms of FGFR3 (Figure 1A, right panel). Thus, FGFR3 promoted colony formation of pancreatic cells, but clone expansion was reduced. This latter effect depended on active FGFR3 tyrosine kinase. Furthermore, forced expression of both FGFR3 splice variants in Capan-2 and BxPC-3 cells reduced the cell proliferation (Figure 1B). Flow cytometry analyses did not evidence major differences in the distributions of cells in the cell cycles phases (Additional file 1: Figure S1), but a significant and important accumulation of cells in sub-G1 was observed, suggesting that FGFR3 induced apoptosis (Additional file 1: Figure S1 and Figure 1C).

Bottom Line: The receptor exerted dual effects: it suppressed tumor growth in pancreatic epithelial-like cells and had oncogenic properties in pancreatic mesenchymal-like cells.Both FGFR3 splice variants had similar effects and used the same intracellular signaling.TKIs against FGFR3 might result in adverse effects if used in the wrong cell context.

View Article: PubMed Central - HTML - PubMed

Affiliation: INSERM U1035, Université Bordeaux Segalen, 146 rue Léo Saignat, Bordeaux 33076, France.

ABSTRACT

Background: Due to frequent mutations in certain cancers, FGFR3 gene is considered as an oncogene. However, in some normal tissues, FGFR3 can limit cell growth and promote cell differentiation. Thus, FGFR3 action appears paradoxical.

Results: FGFR3 expression was forced in pancreatic cell lines. The receptor exerted dual effects: it suppressed tumor growth in pancreatic epithelial-like cells and had oncogenic properties in pancreatic mesenchymal-like cells. Distinct exclusive pathways were activated, STATs in epithelial-like cells and MAP Kinases in mesenchymal-like cells. Both FGFR3 splice variants had similar effects and used the same intracellular signaling. In human pancreatic carcinoma tissues, levels of FGFR3 dropped in tumors.

Conclusion: In tumors from epithelial origin, FGFR3 signal can limit tumor growth, explaining why the 4p16.3 locus bearing FGFR3 is frequently lost and why activating mutations of FGFR3 in benign or low grade tumors of epithelial origin are associated with good prognosis. The new hypothesis that FGFR3 can harbor both tumor suppressive and oncogenic properties is crucial in the context of targeted therapies involving specific tyrosine kinase inhibitors (TKIs). TKIs against FGFR3 might result in adverse effects if used in the wrong cell context.

Show MeSH
Related in: MedlinePlus