Korean J Physiol Pharmacol.  2015 May;19(3):235-240. 10.4196/kjpp.2015.19.3.235.

Androgen Receptor-dependent Expression of Low-density Lipoprotein Receptor-related Protein 6 is Necessary for Prostate Cancer Cell Proliferation

• Park E
• Kim EK
• Kim M
• Ha JM
• Kim YW
• Jin SY
• Shin HK
• Ha HK
• Lee JZ
• Bae SS

• KMID: 1791424
• DOI: http://doi.org/10.4196/kjpp.2015.19.3.235

Abstract

Androgen receptor (AR) signaling is important for prostate cancer (PCa) cell proliferation. Here, we showed that proliferation of hormone-sensitive prostate cancer cells such as LNCaP was significantly enhanced by testosterone stimulation whereas hormone-insensitive prostate cancer cells such as PC3 and VCaP did not respond to testosterone stimulation. Blocking of AR using bicalutamide abolished testosterone-induced proliferation of LNCaP cells. In addition, knockdown of AR blocked testosterone-induced proliferation of LNCaP cells. Basal expression of low-density lipoprotein receptor-related protein 6 (LRP6) was elevated in VCaP cells whereas stimulation of testosterone did not affect the expression of LRP6. However, expression of LRP6 in LNCaP cells was increased by testosterone stimulation. In addition, knockdown of LRP6 abrogated testosterone-induced proliferation of LNCaP cells. Given these results, we suggest that androgen-dependent expression of LRP6 plays a crucial role in hormone-sensitive prostate cancer cell proliferation.

Keyword

Androgen receptor; LRP6; Prostate cancer; Testosterone; Wnt

MeSH Terms

Cell Proliferation*
Low Density Lipoprotein Receptor-Related Protein-6*
Prostatic Neoplasms*
Receptors, Androgen
Testosterone
Low Density Lipoprotein Receptor-Related Protein-6
Receptors, Androgen
Testosterone

Figure

• 

  Fig. 1 Testosterone-dependent proliferation of prostate cancer cells. Prostate cancer cells (1×104/well) were plated on 6-well plates, and cultured in the presence or absence of testosterone (10 nM). Cells were stained with DAPI and images were taken at 10× magnification. Cell number was counted at the indicated time points. Data are the means±S.D. of three independent experiments (n=3 for each experiment). *Significantly different from values at the indicated time point of untreated cells (p<0.05).

• 

  Fig. 2 Effect of AR inhibitor on the testosterone-induced proliferation of prostate cancer cells. Prostate cancer cells (1×104/well) were plated on 6-well plates, and cultured with testosterone (10 nM) in the presence or absence of AR inhibitor (bicalutamide, 10 µM). Cells were stained with DAPI and images were taken at 10× magnification. Cell number was counted at the indicated time points. Data are the means±S.D. of three independent experiments (n=3 for each experiment). *Significantly different from values at the indicated time point of testosterone treated cells (p<0.05).

• 

  Fig. 3 Effect of AR knockdown on the testosterone-induced proliferation of prostate cancer cells. AR was silenced in each prostate cancer cell as described in "Materials and Methods". Expression of AR was verified by RTPCR (top panel). Cells (1×104/well) were plated on 6-well plates, and cultured in the presence of testosterone (10 nM). Cells were stained with DAPI and images were taken at 10× magnification (middle panel). Cell number was counted at the indicated time points (bottom panel). Data are the means±S.D. of three independent experiments (n=3 for each experiment). *Significantly different from values at the indicated time point of vector infected cells (p<0.05).

• 

  Fig. 4 Induction of LRP6 by AR stimulation. Prostate cancer cells were stimulated with testosterone (10 nM). mRNA was isolated and expression of AR, LRP6, and GAPDH was verified by RT-PCR (A). To quantify the expression of LRP-6, mRAN was quantified by real-time Q-PCR using fluorescent reporter dye (B). GAPDH was used as internal control. Data are the means±S.D. of three independent experiments (n=3 for each experiment). *Significantly different from values at the indicated time point of vector infected cells (p<0.05).

• 

  Fig. 5 Effect of LRP6 knockdown on the testosterone-induced proliferation of prostate cancer cells. LRP6 was silenced in each prostate cancer cell as described in "Materials and Methods". Expression of LRP6 was verified by RT-PCR (top panel). Cells (1×104/well) were plated on 6-well plates, and cultured in the presence of testosterone (10 nM). Cells were stained with DAPI and images were taken at 10× magnification (middle panel). Cell number was counted at the indicated time points (bottom panel). Data are the means±S.D. of three independent experiments (n=3 for each experiment). *Significantly different from values at the indicated time point of vector infected cells (p<0.05).

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