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Silencing of PMEPA1 accelerates the growth of prostate cancer cells through AR, NEDD4 and PTEN.

Li H, Mohamed AA, Sharad S, Umeda E, Song Y, Young D, Petrovics G, McLeod DG, Sesterhenn IA, Sreenath T, Dobi A, Srivastava S - Oncotarget (2015)

Bottom Line: In cell culture models knockdown of PMEPA1 resulted in resistance to AR inhibitors enzalutamide and bicalutamide.This study highlights that silencing of PMEPA1 accelerates the growth of CaP cells through AR, NEDD4 and PTEN.The restoration of PMEPA1 represents a promising complementary therapeutic strategy correcting for AR and PTEN defects.

View Article: PubMed Central - PubMed

Affiliation: Center for Prostate Disease Research, Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.

ABSTRACT
Androgen Receptor (AR) is the male hormone receptor and a nuclear transcription factor which plays a central role in the growth of normal and malignant prostate gland. Our earlier studies defined a mechanistic model for male hormone dependent regulation of AR protein levels in prostate cancer (CaP) cells through a negative feed-back loop between AR and PMEPA1, an androgen induced NEDD4 E3 ubiquitin ligase binding protein. This report focuses on the impact of PMEPA1 silencing on CaP biology. PMEPA1 knockdown accelerated the growth of CaP tumor cells in athymic nude mice. In cell culture models knockdown of PMEPA1 resulted in resistance to AR inhibitors enzalutamide and bicalutamide. While, AR protein down regulation by NEDD4 was PMEPA1 dependent, we also noted a PMEPA1 independent downregulation of PTEN by NEDD4. In a subset of human CaP, decreased PMEPA1 mRNA expression significantly correlated with increased levels of AR transcription target PSA, as a surrogate for elevated AR. This study highlights that silencing of PMEPA1 accelerates the growth of CaP cells through AR, NEDD4 and PTEN. Thus, the therapeutic restoration of PMEPA1 represents a promising complementary strategy correcting for AR and PTEN defects in CaP. Statement of significance: Here we define that silencing of PMEPA1 facilitates the growth of CaP cells and modulates AR through NEDD4 and PTEN. The restoration of PMEPA1 represents a promising complementary therapeutic strategy correcting for AR and PTEN defects.

No MeSH data available.


Related in: MedlinePlus

NEDD4 down-regulates of AR protein level and AR signaling, as well as inhibits the growth of LNCaP and VCaP cells(A) Inhibition of NEDD4 by siRNA (NEDD4 si1 and si2) enhances AR and PSA protein levels in LNCaP and VCaP cells. (B) Ectopic expression of NEDD4 decreases AR and PSA in LNCaP and VCaP cells. (C) Cell counting assay reveals that NEDD4 siRNA (NEDD4 si1 and si2) increases the growth of LNCaP cells (p < 0.05). (D) Conversely, ectopic expression of NEDD4 inhibits the growth of LNCaP cells (p < 0.05) as shown by cell counting assay. (E) As expected, MDM2 siRNA (MDM2 si1 and si2) also increases AR and PSA protein levels in LNCaP and VCaP cells.
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Figure 5: NEDD4 down-regulates of AR protein level and AR signaling, as well as inhibits the growth of LNCaP and VCaP cells(A) Inhibition of NEDD4 by siRNA (NEDD4 si1 and si2) enhances AR and PSA protein levels in LNCaP and VCaP cells. (B) Ectopic expression of NEDD4 decreases AR and PSA in LNCaP and VCaP cells. (C) Cell counting assay reveals that NEDD4 siRNA (NEDD4 si1 and si2) increases the growth of LNCaP cells (p < 0.05). (D) Conversely, ectopic expression of NEDD4 inhibits the growth of LNCaP cells (p < 0.05) as shown by cell counting assay. (E) As expected, MDM2 siRNA (MDM2 si1 and si2) also increases AR and PSA protein levels in LNCaP and VCaP cells.

Mentions: Our previous study has revealed that PMEPA1 binds to NEDD4 through the interaction between PY motifs of PMEPA1 and WW domain of human NEDD4 protein [17]. Thus, we evaluated the role of NEDD4 on CaP cell growth and AR protein levels. Knockdown of NEDD4 by specific siRNA led to strikingly elevated levels of AR and PSA in LNCaP and VCaP cells (Figure 5A). Conversely, ectopic expression of the NEDD4 resulted in decreased levels of AR protein in both LNCaP and VCaP cells (Figure 5B). Further, ectopic expression of NEDD4 resulted in a significant inhibition of cell growth (Figure 5C and 5D). In parallel, we also evaluated the effects MDM2 E3 ligase on AR which has been reported to be involved in AR degradation [15]. As expected, transfection of the MDM2 siRNA, resulted in elevated AR and PSA protein levels in both LNCaP and VCaP cells (Figure 5E and 5F). Taken together, these findings underscored that NEDD4 mediates AR degradation and cell growth inhibition in hormone responsive VCaP and LNCaP cells.


Silencing of PMEPA1 accelerates the growth of prostate cancer cells through AR, NEDD4 and PTEN.

Li H, Mohamed AA, Sharad S, Umeda E, Song Y, Young D, Petrovics G, McLeod DG, Sesterhenn IA, Sreenath T, Dobi A, Srivastava S - Oncotarget (2015)

NEDD4 down-regulates of AR protein level and AR signaling, as well as inhibits the growth of LNCaP and VCaP cells(A) Inhibition of NEDD4 by siRNA (NEDD4 si1 and si2) enhances AR and PSA protein levels in LNCaP and VCaP cells. (B) Ectopic expression of NEDD4 decreases AR and PSA in LNCaP and VCaP cells. (C) Cell counting assay reveals that NEDD4 siRNA (NEDD4 si1 and si2) increases the growth of LNCaP cells (p < 0.05). (D) Conversely, ectopic expression of NEDD4 inhibits the growth of LNCaP cells (p < 0.05) as shown by cell counting assay. (E) As expected, MDM2 siRNA (MDM2 si1 and si2) also increases AR and PSA protein levels in LNCaP and VCaP cells.
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Related In: Results  -  Collection

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Figure 5: NEDD4 down-regulates of AR protein level and AR signaling, as well as inhibits the growth of LNCaP and VCaP cells(A) Inhibition of NEDD4 by siRNA (NEDD4 si1 and si2) enhances AR and PSA protein levels in LNCaP and VCaP cells. (B) Ectopic expression of NEDD4 decreases AR and PSA in LNCaP and VCaP cells. (C) Cell counting assay reveals that NEDD4 siRNA (NEDD4 si1 and si2) increases the growth of LNCaP cells (p < 0.05). (D) Conversely, ectopic expression of NEDD4 inhibits the growth of LNCaP cells (p < 0.05) as shown by cell counting assay. (E) As expected, MDM2 siRNA (MDM2 si1 and si2) also increases AR and PSA protein levels in LNCaP and VCaP cells.
Mentions: Our previous study has revealed that PMEPA1 binds to NEDD4 through the interaction between PY motifs of PMEPA1 and WW domain of human NEDD4 protein [17]. Thus, we evaluated the role of NEDD4 on CaP cell growth and AR protein levels. Knockdown of NEDD4 by specific siRNA led to strikingly elevated levels of AR and PSA in LNCaP and VCaP cells (Figure 5A). Conversely, ectopic expression of the NEDD4 resulted in decreased levels of AR protein in both LNCaP and VCaP cells (Figure 5B). Further, ectopic expression of NEDD4 resulted in a significant inhibition of cell growth (Figure 5C and 5D). In parallel, we also evaluated the effects MDM2 E3 ligase on AR which has been reported to be involved in AR degradation [15]. As expected, transfection of the MDM2 siRNA, resulted in elevated AR and PSA protein levels in both LNCaP and VCaP cells (Figure 5E and 5F). Taken together, these findings underscored that NEDD4 mediates AR degradation and cell growth inhibition in hormone responsive VCaP and LNCaP cells.

Bottom Line: In cell culture models knockdown of PMEPA1 resulted in resistance to AR inhibitors enzalutamide and bicalutamide.This study highlights that silencing of PMEPA1 accelerates the growth of CaP cells through AR, NEDD4 and PTEN.The restoration of PMEPA1 represents a promising complementary therapeutic strategy correcting for AR and PTEN defects.

View Article: PubMed Central - PubMed

Affiliation: Center for Prostate Disease Research, Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.

ABSTRACT
Androgen Receptor (AR) is the male hormone receptor and a nuclear transcription factor which plays a central role in the growth of normal and malignant prostate gland. Our earlier studies defined a mechanistic model for male hormone dependent regulation of AR protein levels in prostate cancer (CaP) cells through a negative feed-back loop between AR and PMEPA1, an androgen induced NEDD4 E3 ubiquitin ligase binding protein. This report focuses on the impact of PMEPA1 silencing on CaP biology. PMEPA1 knockdown accelerated the growth of CaP tumor cells in athymic nude mice. In cell culture models knockdown of PMEPA1 resulted in resistance to AR inhibitors enzalutamide and bicalutamide. While, AR protein down regulation by NEDD4 was PMEPA1 dependent, we also noted a PMEPA1 independent downregulation of PTEN by NEDD4. In a subset of human CaP, decreased PMEPA1 mRNA expression significantly correlated with increased levels of AR transcription target PSA, as a surrogate for elevated AR. This study highlights that silencing of PMEPA1 accelerates the growth of CaP cells through AR, NEDD4 and PTEN. Thus, the therapeutic restoration of PMEPA1 represents a promising complementary strategy correcting for AR and PTEN defects in CaP. Statement of significance: Here we define that silencing of PMEPA1 facilitates the growth of CaP cells and modulates AR through NEDD4 and PTEN. The restoration of PMEPA1 represents a promising complementary therapeutic strategy correcting for AR and PTEN defects.

No MeSH data available.


Related in: MedlinePlus