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IGF2BP3-mediated translation in cell protrusions promotes cell invasiveness and metastasis of pancreatic cancer.

Taniuchi K, Furihata M, Hanazaki K, Saito M, Saibara T - Oncotarget (2014)

Bottom Line: Specific IGF2BP3-bound transcripts-ARF6 and ARHGEF4-that are preferentially translated in membrane protrusions induce further formation of membrane protrusions; consequently, IGF2BP3 promotes cell invasiveness and tumor metastasis.Our results provide insight into the link between regulation of localized translation in cell protrusions and the invasiveness and metastasis of pancreatic cancers.New therapies that prevent local translation in cell protrusions may hold significant clinical promise.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi , Japan.

ABSTRACT
Pancreatic cancers are aggressive because they are highly invasive and highly metastatic; moreover, effective treatments for aggressive pancreatic cancers are lacking. Here, we report that IGF2BP3 promoted the invasiveness and metastasis of pancreatic cancers through locally translated IGF2BP3-bound transcripts. In neural cells, transcripts sorted into cytoplasmic RNA granules are transported to dendrites and translated in these dendrites, thereby mediating long-term synaptic plasticity; however, such cytoplasmic RNA granules are not known to contribute to the progression of pancreatic cancer. We show evidence that IGF2BP3 and IGF2BP3-bound transcripts are localized in cytoplasmic RNA granules that accumulate in membrane protrusions of pancreatic cancer cells. Specific IGF2BP3-bound transcripts-ARF6 and ARHGEF4-that are preferentially translated in membrane protrusions induce further formation of membrane protrusions; consequently, IGF2BP3 promotes cell invasiveness and tumor metastasis. Our results provide insight into the link between regulation of localized translation in cell protrusions and the invasiveness and metastasis of pancreatic cancers. New therapies that prevent local translation in cell protrusions may hold significant clinical promise.

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IGF2BP3 associates with forming cell protrusions(A) Confocal Z stack shows phalloidin-labeled peripheral actin structures (red) and DAPI-labeled nuclei (blue) in fibronectin-stimulated scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells transfected with or without the myc-tagged IGF2BP3-rescue construct. Arrows, peripheral actin structures in cell protrusions. The lower and right panels in the confocal Z stack show a vertical cross-section (yellow lines) through the cells. Bars, 10 μm. (B) Quantification of data shown in Figure 6A; the values represent the number of cells with fibronectin-mediated cell protrusions in which peripheral actin structures were increased. All cells in four fields per group were scored. Data derive from three independent experiments. Columns, mean; bars, SD. *p < 0.001 compared with Scr-1 or siIGF-1 transfected mock vector (Student's t-test). (C) After scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells were cultured on fibronectin for 4 h, the morphology of each cell was analyzed by phase-contact microscopy. (D) Immunohistochemical staining with anti-IGF2BP3 and anti-ARF6 antibodies in control or IGF2BP3-RNAi S2-013 primary pancreatic tumors in mice. Representative sections (× 400). Arrows, ARF6 localized near cell membranes.
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Figure 6: IGF2BP3 associates with forming cell protrusions(A) Confocal Z stack shows phalloidin-labeled peripheral actin structures (red) and DAPI-labeled nuclei (blue) in fibronectin-stimulated scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells transfected with or without the myc-tagged IGF2BP3-rescue construct. Arrows, peripheral actin structures in cell protrusions. The lower and right panels in the confocal Z stack show a vertical cross-section (yellow lines) through the cells. Bars, 10 μm. (B) Quantification of data shown in Figure 6A; the values represent the number of cells with fibronectin-mediated cell protrusions in which peripheral actin structures were increased. All cells in four fields per group were scored. Data derive from three independent experiments. Columns, mean; bars, SD. *p < 0.001 compared with Scr-1 or siIGF-1 transfected mock vector (Student's t-test). (C) After scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells were cultured on fibronectin for 4 h, the morphology of each cell was analyzed by phase-contact microscopy. (D) Immunohistochemical staining with anti-IGF2BP3 and anti-ARF6 antibodies in control or IGF2BP3-RNAi S2-013 primary pancreatic tumors in mice. Representative sections (× 400). Arrows, ARF6 localized near cell membranes.

Mentions: Confocal microscopy was used to examine the 3-dimentional configurations of peripheral actin structures and cell protrusions in fibronectin-stimulated S2-013 cells. Peripheral actin structures (Figure 6A) and cell protrusions (Figure 6B) were less abundant in IGF2BP3-RNAi S2-013 cells than in control-RNAi S2-013 cells. Conversely, phalloidin-labeled actin structures were more abundant in the cytoplasm of the cell bodies of IGF2BP3-RNAi S2-013 cells than that of control-RNAi S2-013 cells (Figure 6A). Transfection of an IGF2BP3-rescue construct renewed peripheral actin structures in IGF2BP3-RNAi S2-013 cells (Figure 6A). Cell protrusions were significantly more abundant in IGF2BP3-RNAi S2-013 cells carrying an IGF2BP3-rescue construct than in IGF2BP3-RNAi S2-013 cells lacking this contruct (Figure 6B). Whereas parental control-RNAi S2-013 clones exhibited spindle-shaped cells and fibroblastic morphology, IGF2BP3-RNAi cells typically displayed a cobblestone-like, epithelial morphology (Figure 6C). These results indicated that IGF2BP3 drove rearrangement of peripheral actin to induce formation of additional membrane protrusions.


IGF2BP3-mediated translation in cell protrusions promotes cell invasiveness and metastasis of pancreatic cancer.

Taniuchi K, Furihata M, Hanazaki K, Saito M, Saibara T - Oncotarget (2014)

IGF2BP3 associates with forming cell protrusions(A) Confocal Z stack shows phalloidin-labeled peripheral actin structures (red) and DAPI-labeled nuclei (blue) in fibronectin-stimulated scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells transfected with or without the myc-tagged IGF2BP3-rescue construct. Arrows, peripheral actin structures in cell protrusions. The lower and right panels in the confocal Z stack show a vertical cross-section (yellow lines) through the cells. Bars, 10 μm. (B) Quantification of data shown in Figure 6A; the values represent the number of cells with fibronectin-mediated cell protrusions in which peripheral actin structures were increased. All cells in four fields per group were scored. Data derive from three independent experiments. Columns, mean; bars, SD. *p < 0.001 compared with Scr-1 or siIGF-1 transfected mock vector (Student's t-test). (C) After scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells were cultured on fibronectin for 4 h, the morphology of each cell was analyzed by phase-contact microscopy. (D) Immunohistochemical staining with anti-IGF2BP3 and anti-ARF6 antibodies in control or IGF2BP3-RNAi S2-013 primary pancreatic tumors in mice. Representative sections (× 400). Arrows, ARF6 localized near cell membranes.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 6: IGF2BP3 associates with forming cell protrusions(A) Confocal Z stack shows phalloidin-labeled peripheral actin structures (red) and DAPI-labeled nuclei (blue) in fibronectin-stimulated scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells transfected with or without the myc-tagged IGF2BP3-rescue construct. Arrows, peripheral actin structures in cell protrusions. The lower and right panels in the confocal Z stack show a vertical cross-section (yellow lines) through the cells. Bars, 10 μm. (B) Quantification of data shown in Figure 6A; the values represent the number of cells with fibronectin-mediated cell protrusions in which peripheral actin structures were increased. All cells in four fields per group were scored. Data derive from three independent experiments. Columns, mean; bars, SD. *p < 0.001 compared with Scr-1 or siIGF-1 transfected mock vector (Student's t-test). (C) After scrambled control-RNAi (Scr-1) S2-013 cells or IGF2BP3-RNAi (siIGF-1) S2-013 cells were cultured on fibronectin for 4 h, the morphology of each cell was analyzed by phase-contact microscopy. (D) Immunohistochemical staining with anti-IGF2BP3 and anti-ARF6 antibodies in control or IGF2BP3-RNAi S2-013 primary pancreatic tumors in mice. Representative sections (× 400). Arrows, ARF6 localized near cell membranes.
Mentions: Confocal microscopy was used to examine the 3-dimentional configurations of peripheral actin structures and cell protrusions in fibronectin-stimulated S2-013 cells. Peripheral actin structures (Figure 6A) and cell protrusions (Figure 6B) were less abundant in IGF2BP3-RNAi S2-013 cells than in control-RNAi S2-013 cells. Conversely, phalloidin-labeled actin structures were more abundant in the cytoplasm of the cell bodies of IGF2BP3-RNAi S2-013 cells than that of control-RNAi S2-013 cells (Figure 6A). Transfection of an IGF2BP3-rescue construct renewed peripheral actin structures in IGF2BP3-RNAi S2-013 cells (Figure 6A). Cell protrusions were significantly more abundant in IGF2BP3-RNAi S2-013 cells carrying an IGF2BP3-rescue construct than in IGF2BP3-RNAi S2-013 cells lacking this contruct (Figure 6B). Whereas parental control-RNAi S2-013 clones exhibited spindle-shaped cells and fibroblastic morphology, IGF2BP3-RNAi cells typically displayed a cobblestone-like, epithelial morphology (Figure 6C). These results indicated that IGF2BP3 drove rearrangement of peripheral actin to induce formation of additional membrane protrusions.

Bottom Line: Specific IGF2BP3-bound transcripts-ARF6 and ARHGEF4-that are preferentially translated in membrane protrusions induce further formation of membrane protrusions; consequently, IGF2BP3 promotes cell invasiveness and tumor metastasis.Our results provide insight into the link between regulation of localized translation in cell protrusions and the invasiveness and metastasis of pancreatic cancers.New therapies that prevent local translation in cell protrusions may hold significant clinical promise.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi , Japan.

ABSTRACT
Pancreatic cancers are aggressive because they are highly invasive and highly metastatic; moreover, effective treatments for aggressive pancreatic cancers are lacking. Here, we report that IGF2BP3 promoted the invasiveness and metastasis of pancreatic cancers through locally translated IGF2BP3-bound transcripts. In neural cells, transcripts sorted into cytoplasmic RNA granules are transported to dendrites and translated in these dendrites, thereby mediating long-term synaptic plasticity; however, such cytoplasmic RNA granules are not known to contribute to the progression of pancreatic cancer. We show evidence that IGF2BP3 and IGF2BP3-bound transcripts are localized in cytoplasmic RNA granules that accumulate in membrane protrusions of pancreatic cancer cells. Specific IGF2BP3-bound transcripts-ARF6 and ARHGEF4-that are preferentially translated in membrane protrusions induce further formation of membrane protrusions; consequently, IGF2BP3 promotes cell invasiveness and tumor metastasis. Our results provide insight into the link between regulation of localized translation in cell protrusions and the invasiveness and metastasis of pancreatic cancers. New therapies that prevent local translation in cell protrusions may hold significant clinical promise.

Show MeSH
Related in: MedlinePlus