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Insulin-like growth factor-binding protein-2 promotes prostate cancer cell growth via IGF-dependent or -independent mechanisms and reduces the efficacy of docetaxel.

Uzoh CC, Holly JM, Biernacka KM, Persad RA, Bahl A, Gillatt D, Perks CM - Br. J. Cancer (2011)

Bottom Line: Understanding the resistance to therapy could aid the development of more effective treatments.The IGFBP-2 promoted cell growth in both cell lines but with PC3 cells this was in an IGF-dependent manner, whereas with DU145 cells the effect was independent of IGF receptor activation.This IGF-independent effect of IGFBP-2 was mediated by interaction with β-1-containing integrins and a consequent increase in PTEN phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: IGFs and Metabolic Endocrinology Group, School of Clinical Sciences, Learning and Research Building, Southmead Hospital, Bristol, UK.

ABSTRACT

Background: The development of androgen independence, chemo-, and radioresistance are critical markers of prostate cancer progression and the predominant reasons for its high mortality. Understanding the resistance to therapy could aid the development of more effective treatments.

Aim: The aim of this study is to investigate the effects of insulin-like growth factor-binding protein-2 (IGFBP-2) on prostate cancer cell proliferation and its effects on the response to docetaxel.

Methods: DU145 and PC3 cells were treated with IGFBP-2, insulin-like growth factor I (IGF-I) alone or in combination with blockade of the IGF-I receptor or integrin receptors. Cells were also treated with IGFBP-2 short interfering ribonucleic acid with or without a PTEN (phosphatase and tensin homologue deleted on chromosome 10) inhibitor or docetaxel. Tritiated thymidine incorporation was used to measure cell proliferation and Trypan blue cell counting for cell death. Levels of IGFBP-2 mRNA were measured using RT-PCR. Abundance and phosphorylation of proteins were assessed using western immunoblotting.

Results: The IGFBP-2 promoted cell growth in both cell lines but with PC3 cells this was in an IGF-dependent manner, whereas with DU145 cells the effect was independent of IGF receptor activation. This IGF-independent effect of IGFBP-2 was mediated by interaction with β-1-containing integrins and a consequent increase in PTEN phosphorylation. We also determined that silencing IGFBP-2 in both cell lines increased the sensitivity of the cells to docetaxel.

Conclusion: The IGFBP-2 has a key role in the growth of prostate cancer cells, and silencing IGFBP-2 expression reduced the resistance of these cells to docetaxel. Targeting IGFBP-2 may increase the efficacy of docetaxel.

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Related in: MedlinePlus

Effects of IGFBP-2 on the proliferation of prostate cancer cells. (A and B) Graphs show TTI for DU145 (A) and PC3 (B) cells (0.25 × 105 per well; 24-well plates) treated for 48 h with increasing concentrations of IGFBP-2 (0–1000 ng ml−1) after initial plating in GM for 24 h and serum starving for a further 24 h. (C and D) Graph shows total cell number of DU145 (C) and PC3 (D) cells (0.2 × 106 per well; six-well plates) pre-dosed for 1 h with 1 μ of AG1024–IGF-IR tyrosine kinase inhibitor or SFM. Cells were then spiked with IGF-I (125 ng ml−1) or IGFBP-2 (250 ng ml−1) for 48 h after initial plating in GM for 24 h and serum starving for a further 24 h. Graphs are representative of experiments repeated three times showing the mean±s.e.m.
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fig1: Effects of IGFBP-2 on the proliferation of prostate cancer cells. (A and B) Graphs show TTI for DU145 (A) and PC3 (B) cells (0.25 × 105 per well; 24-well plates) treated for 48 h with increasing concentrations of IGFBP-2 (0–1000 ng ml−1) after initial plating in GM for 24 h and serum starving for a further 24 h. (C and D) Graph shows total cell number of DU145 (C) and PC3 (D) cells (0.2 × 106 per well; six-well plates) pre-dosed for 1 h with 1 μ of AG1024–IGF-IR tyrosine kinase inhibitor or SFM. Cells were then spiked with IGF-I (125 ng ml−1) or IGFBP-2 (250 ng ml−1) for 48 h after initial plating in GM for 24 h and serum starving for a further 24 h. Graphs are representative of experiments repeated three times showing the mean±s.e.m.

Mentions: Addition of IGFBP-2 caused a dose-dependent increase in tritiated thymidine uptake in DU145 cells after 48 h, with significant effects occurring from 62.5 ng ml−1 IGFBP-2 (P<0.05; Figure 1A). This effect was also seen with PC3 cells (Figure 1B). Cell counting produced a similar trend in each of these cell lines (data not shown).


Insulin-like growth factor-binding protein-2 promotes prostate cancer cell growth via IGF-dependent or -independent mechanisms and reduces the efficacy of docetaxel.

Uzoh CC, Holly JM, Biernacka KM, Persad RA, Bahl A, Gillatt D, Perks CM - Br. J. Cancer (2011)

Effects of IGFBP-2 on the proliferation of prostate cancer cells. (A and B) Graphs show TTI for DU145 (A) and PC3 (B) cells (0.25 × 105 per well; 24-well plates) treated for 48 h with increasing concentrations of IGFBP-2 (0–1000 ng ml−1) after initial plating in GM for 24 h and serum starving for a further 24 h. (C and D) Graph shows total cell number of DU145 (C) and PC3 (D) cells (0.2 × 106 per well; six-well plates) pre-dosed for 1 h with 1 μ of AG1024–IGF-IR tyrosine kinase inhibitor or SFM. Cells were then spiked with IGF-I (125 ng ml−1) or IGFBP-2 (250 ng ml−1) for 48 h after initial plating in GM for 24 h and serum starving for a further 24 h. Graphs are representative of experiments repeated three times showing the mean±s.e.m.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3101905&req=5

fig1: Effects of IGFBP-2 on the proliferation of prostate cancer cells. (A and B) Graphs show TTI for DU145 (A) and PC3 (B) cells (0.25 × 105 per well; 24-well plates) treated for 48 h with increasing concentrations of IGFBP-2 (0–1000 ng ml−1) after initial plating in GM for 24 h and serum starving for a further 24 h. (C and D) Graph shows total cell number of DU145 (C) and PC3 (D) cells (0.2 × 106 per well; six-well plates) pre-dosed for 1 h with 1 μ of AG1024–IGF-IR tyrosine kinase inhibitor or SFM. Cells were then spiked with IGF-I (125 ng ml−1) or IGFBP-2 (250 ng ml−1) for 48 h after initial plating in GM for 24 h and serum starving for a further 24 h. Graphs are representative of experiments repeated three times showing the mean±s.e.m.
Mentions: Addition of IGFBP-2 caused a dose-dependent increase in tritiated thymidine uptake in DU145 cells after 48 h, with significant effects occurring from 62.5 ng ml−1 IGFBP-2 (P<0.05; Figure 1A). This effect was also seen with PC3 cells (Figure 1B). Cell counting produced a similar trend in each of these cell lines (data not shown).

Bottom Line: Understanding the resistance to therapy could aid the development of more effective treatments.The IGFBP-2 promoted cell growth in both cell lines but with PC3 cells this was in an IGF-dependent manner, whereas with DU145 cells the effect was independent of IGF receptor activation.This IGF-independent effect of IGFBP-2 was mediated by interaction with β-1-containing integrins and a consequent increase in PTEN phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: IGFs and Metabolic Endocrinology Group, School of Clinical Sciences, Learning and Research Building, Southmead Hospital, Bristol, UK.

ABSTRACT

Background: The development of androgen independence, chemo-, and radioresistance are critical markers of prostate cancer progression and the predominant reasons for its high mortality. Understanding the resistance to therapy could aid the development of more effective treatments.

Aim: The aim of this study is to investigate the effects of insulin-like growth factor-binding protein-2 (IGFBP-2) on prostate cancer cell proliferation and its effects on the response to docetaxel.

Methods: DU145 and PC3 cells were treated with IGFBP-2, insulin-like growth factor I (IGF-I) alone or in combination with blockade of the IGF-I receptor or integrin receptors. Cells were also treated with IGFBP-2 short interfering ribonucleic acid with or without a PTEN (phosphatase and tensin homologue deleted on chromosome 10) inhibitor or docetaxel. Tritiated thymidine incorporation was used to measure cell proliferation and Trypan blue cell counting for cell death. Levels of IGFBP-2 mRNA were measured using RT-PCR. Abundance and phosphorylation of proteins were assessed using western immunoblotting.

Results: The IGFBP-2 promoted cell growth in both cell lines but with PC3 cells this was in an IGF-dependent manner, whereas with DU145 cells the effect was independent of IGF receptor activation. This IGF-independent effect of IGFBP-2 was mediated by interaction with β-1-containing integrins and a consequent increase in PTEN phosphorylation. We also determined that silencing IGFBP-2 in both cell lines increased the sensitivity of the cells to docetaxel.

Conclusion: The IGFBP-2 has a key role in the growth of prostate cancer cells, and silencing IGFBP-2 expression reduced the resistance of these cells to docetaxel. Targeting IGFBP-2 may increase the efficacy of docetaxel.

Show MeSH
Related in: MedlinePlus