Chonnam Med J.  2012 Dec;48(3):174-178. 10.4068/cmj.2012.48.3.174.

Expression and Localization of Aquaporins in Benign Prostate Hyperplasia and Prostate Cancer

• Hwang I
• Jung SI
• Hwang EC
• Song SH
• Lee HS
• Kim SO
• Kang TW
• Kwon D
• Park K

• KMID: 2048808
• DOI: http://doi.org/10.4068/cmj.2012.48.3.174

Abstract

The aquaporin (AQP) families of water channels are intrinsic membrane proteins that facilitate selective water and small solute movement across the plasma membrane. The purposes of this study were to determine the expression and localization of AQPs in benign prostatic hyperplasia and prostate cancer. Prostatic tissue was collected from patients with benign prostatic hyperplasia or prostate cancer by transurethral resection of the prostate. The expression and cellular localization of the AQPs were determined in the human prostate by Western blot and immunohistochemistry. AQP1, 3, and 9 were expressed in the human prostate. Western blot analysis revealed bands at 28-36 kDa for the AQP1, 3, and 9 proteins. Of these proteins, AQP3 and 9 were expressed in the epithelium. Immunolabeling showed that AQP1 was mainly expressed in the capillaries and venules of the prostate, AQP9 was expressed in the cytoplasm of the epithelium, and AQP3 was mainly associated with the plasma membrane of the prostatic epithelium. Only AQP3 expression was localized in the cell membrane, and expressed AQP3 was translocated to the cytoplasm in prostate cancer. The epithelium in the human prostate expresses AQP3 and 9 proteins, and the capillaries and venules of the prostate express AQP1. Characterizing or modifying the expression of AQP3 may lead to an understanding of the role of the AQPs in human prostatic disease.

Keyword

Prostatic hyperplasia; Prostatic neoplasms; Aquaporins; Humans

MeSH Terms

Aquaporins
Blotting, Western
Capillaries
Cell Membrane
Cytoplasm
Epithelium
Humans
Hyperplasia
Immunohistochemistry
Membrane Proteins
Prostate
Prostatic Diseases
Prostatic Hyperplasia
Prostatic Neoplasms
Proteins
Venules
Aquaporins
Membrane Proteins
Proteins

Figure

• 

  FIG. 1 Western blot analysis of AQP expression in benign prostatic hyperplasia. Anti-AQP antibody recognized bands at 28 to 36 kD, which corresponded to AQP1, 3, and 9 protein (AQP1: 28 kDa, AQP3: 36 kDa, AQP9: 29 kDa).

• 

  FIG. 2 Representative immunofluorescence confocal microscopic images of AQP1 (A), AQP3 (B), and AQP9 (C) in benign prostatic hyperplasia. (A) Images of AQP1 localization in the prostate. AQP1 was detected along the endothelium of the capillaries and venules of the prostate (arrow). (B) Images of AQP3 localization in the prostates. AQP3 was evident in the plasma membrane of the epithelium of the prostate (arrow). (C) Images of AQP9 localization in the prostate. AQP9 was observed in the cytoplasm of the epithelium of the prostate (arrow).

• 

  FIG. 3 Representative immunofluorescence confocal microscopic images of AQP1 (A) and AQP3 (B) in prostate cancer. (A) Immunofluorescence confocal microscopic images of AQP1 localization in prostate cancer. AQP1 was detected along the endothelium of the capillaries and venules of the prostate (arrow). (B) Immunofluorescence confocal microscopic images of AQP3 localization in the prostate cancer. AQP3 was observed in the cytoplasm of the epithelium of the prostate (arrow).

Reference

1. Verkman AS, Mitra AK. Structure and function of aquaporin water channels. Am J Physiol Renal Physiol. 2000. 278:F13–F28.

2. Zardoya R. Phylogeny and evolution of the major intrinsic protein family. Biol Cell. 2005. 97:397–414.

3. Huang HF, He RH, Sun CC, Zhang Y, Meng QX, Ma YY. Function of aquaporins in female and male reproductive systems. Hum Reprod Update. 2006. 12:785–795.

4. Agre P, Kozono D. Aquaporin water channels: molecular mechanisms for human diseases. FEBS Lett. 2003. 555:72–78.

5. Verkman AS. More than just water channels: unexpected cellular roles of aquaporins. J Cell Sci. 2005. 118:3225–3232.

6. Verkman AS, Hara-Chikuma M, Papadopoulos MC. Aquaporins-new players in cancer biology. J Mol Med (Berl). 2008. 86:523–529.

7. Jablonski EM, Webb AN, McConnell NA, Riley MC, Hughes FM Jr. Plasma membrane aquaporin activity can affect the rate of apoptosis but is inhibited after apoptotic volume decrease. Am J Physiol Cell Physiol. 2004. 286:C975–C985.

8. Jablonski EM, Mattocks MA, Sokolov E, Koniaris LG, Hughes FM Jr, Fausto N, et al. Decreased aquaporin expression leads to increased resistance to apoptosis in hepatocellular carcinoma. Cancer Lett. 2007. 250:36–46.

9. Cho YS, Svelto M, Calamita G. Possible functional implications of aquaporin water channels in reproductive physiology and medically assisted procreation. Cell Mol Biol (Noisy-le-grand). 2003. 49:515–519.

10. Wang J, Tanji N, Kikugawa T, Shudou M, Song X, Yokoyama M. Expression of aquaporin 3 in the human prostate. Int J Urol. 2007. 14:1088–1092.

11. Mobasheri A, Wray S, Marples D. Distribution of AQP2 and AQP3 water channels in human tissue microarrays. J Mol Histol. 2005. 36:1–14.

12. Nielsen S, Kwon TH, Christensen BM, Promeneur D, Frøkiaer J, Marples D. Physiology and pathophysiology of renal aquaporins. J Am Soc Nephrol. 1999. 10:647–663.

13. Ishibashi K, Sasaki S, Fushimi K, Uchida S, Kuwahara M, Saito H, et al. Molecular cloning and expression of a member of the aquaporin family with permeability to glycerol and urea in addition to water expressed at the basolateral membrane of kidney collecting duct cells. Proc Natl Acad Sci U S A. 1994. 91:6269–6273.

14. Fulmer BR, Turner TT. A blood-prostate barrier restricts cell and molecular movement across the rat ventral prostate epithelium. J Urol. 2000. 163:1591–1594.

15. Schrier RW, Cadnapaphornchai MA. Renal aquaporin water channels: from molecules to human disease. Prog Biophys Mol Biol. 2003. 81:117–131.

16. Ismail M, Bokaee S, Morgan R, Davies J, Harrington KJ, Pandha H. Inhibition of the aquaporin 3 water channel increases the sensitivity of prostate cancer cells to cryotherapy. Br J Cancer. 2009. 100:1889–1895.

17. Jung SI, Lee HS, Kim HS, Ahn K, Park K. Effects of castration on the expression of aquaporins and apoptosis in the ventral prostate. J Mens Health. 2012. 9:238–244.