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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

IGFBP-2 affects the sensitivity of CaP to docetaxel. DU145 (A) and PC3 (B) CaP cells were seeded (0.08 × 106 per well; 24-well plates), respectively, in GM and transfected as in Figure 3B for 24 h. They were then subjected to SFM conditions for a further 24 h and then treated for 24 h with docetaxel (30 n for each). Cells were then counted and assessed for cell death. The graphs represent the mean±s.e.m. of three experiments each repeated in triplicate. Insert (B) shows a representative WIB for IGFBP-2 protein and RT–PCR for IGFBP-2 mRNA from PC3 cell lysates showing effective silencing of IGFBP-2 using siRNA.
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fig4: IGFBP-2 affects the sensitivity of CaP to docetaxel. DU145 (A) and PC3 (B) CaP cells were seeded (0.08 × 106 per well; 24-well plates), respectively, in GM and transfected as in Figure 3B for 24 h. They were then subjected to SFM conditions for a further 24 h and then treated for 24 h with docetaxel (30 n for each). Cells were then counted and assessed for cell death. The graphs represent the mean±s.e.m. of three experiments each repeated in triplicate. Insert (B) shows a representative WIB for IGFBP-2 protein and RT–PCR for IGFBP-2 mRNA from PC3 cell lysates showing effective silencing of IGFBP-2 using siRNA.

Mentions: We found that docetaxel induced a significant increase in cell death with DU145 cells (P<0.001) and with PC3 cells (P<0.001) (Figures 4A and B, respectively). The induced cell death was unaffected in the presence of the control, non-silencing siRNA; however, with IGFBP-2 knock down, the response of the cells to docetaxel was increased significantly (P<0.001 for both). With DU145 cells docetaxel-induced death increased 1.95-fold and with PC3 cells the induced death increased 1.47-fold. The insert to Figure 4B shows a WIB for IGFBP-2 illustrating effective silencing in PC3 cells. These data showed that removing IGFBP-2 increased the effect of docetaxel to induce CaP cell death.


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)

IGFBP-2 affects the sensitivity of CaP to docetaxel. DU145 (A) and PC3 (B) CaP cells were seeded (0.08 × 106 per well; 24-well plates), respectively, in GM and transfected as in Figure 3B for 24 h. They were then subjected to SFM conditions for a further 24 h and then treated for 24 h with docetaxel (30 n for each). Cells were then counted and assessed for cell death. The graphs represent the mean±s.e.m. of three experiments each repeated in triplicate. Insert (B) shows a representative WIB for IGFBP-2 protein and RT–PCR for IGFBP-2 mRNA from PC3 cell lysates showing effective silencing of IGFBP-2 using siRNA.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3101905&req=5

fig4: IGFBP-2 affects the sensitivity of CaP to docetaxel. DU145 (A) and PC3 (B) CaP cells were seeded (0.08 × 106 per well; 24-well plates), respectively, in GM and transfected as in Figure 3B for 24 h. They were then subjected to SFM conditions for a further 24 h and then treated for 24 h with docetaxel (30 n for each). Cells were then counted and assessed for cell death. The graphs represent the mean±s.e.m. of three experiments each repeated in triplicate. Insert (B) shows a representative WIB for IGFBP-2 protein and RT–PCR for IGFBP-2 mRNA from PC3 cell lysates showing effective silencing of IGFBP-2 using siRNA.
Mentions: We found that docetaxel induced a significant increase in cell death with DU145 cells (P<0.001) and with PC3 cells (P<0.001) (Figures 4A and B, respectively). The induced cell death was unaffected in the presence of the control, non-silencing siRNA; however, with IGFBP-2 knock down, the response of the cells to docetaxel was increased significantly (P<0.001 for both). With DU145 cells docetaxel-induced death increased 1.95-fold and with PC3 cells the induced death increased 1.47-fold. The insert to Figure 4B shows a WIB for IGFBP-2 illustrating effective silencing in PC3 cells. These data showed that removing IGFBP-2 increased the effect of docetaxel to induce CaP cell death.

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