Korean J Urol.  2015 Mar;56(3):187-196. 10.4111/kju.2015.56.3.187.

Structural modifications of the prostate in hypoxia, oxidative stress, and chronic ischemia

• Thurmond P
• Yang JH
• Li Y
• Lerner LB
• Azadzoi KM

• KMID: 2133286
• DOI: http://doi.org/10.4111/kju.2015.56.3.187

Abstract

PURPOSE
Clinical studies have reported a correlation between pelvic ischemia and voiding dysfunction in elderly men. The aim of this study was to identify and compare prostate structural modifications in cultured cells and in a rabbit model after exposure to hypoxia, oxidative stress, and chronic ischemia.
MATERIALS AND METHODS
Cultured human prostate smooth muscle cells (SMCs), epithelial cells (ECs), and stromal cells (SCs) were incubated under normoxia, hypoxia, and oxidative stress conditions by use of a computerized oxycycler system. We developed a rabbit model of chronic prostate ischemia by creating aorto-iliac arterial atherosclerosis. Markers of oxidative stress were examined by using fluorometric analysis and enzyme immunoassay. Prostate structure was examined by using Masson's trichrome staining and transmission electron microscopy (TEM).
RESULTS
Lipid peroxidation was found in SMCs exposed to hypoxia and in all cell types exposed to oxidative stress. We identified protein oxidation in ECs exposed to hypoxia and in all cell types exposed to oxidative stress. Markers indicating oxidative damage were present in chronically ischemic rabbit prostate tissue. These reactions were associated with DNA damage. Prostate ischemia resulted in epithelial atrophy, loss of smooth muscle, and diffuse fibrosis. TEM showed swollen mitochondria with degraded cristae, loss of membrane, loss of Golgi bodies, degenerated nerves, and disrupted cell-to-cell junctions.
CONCLUSIONS
Human prostate cells exhibited differential reactions to hypoxia and oxidative stress with widespread DNA damage. Structural modifications in ischemic prostate tissue were similar to those in cells exposed to oxidative stress. Structural changes due to ischemia and oxidative stress may contribute to prostatic noncompliance in aging men.

Keyword

Fibrosis; Ischemia; Oxidative stress; Prostate

MeSH Terms

Animals
Anoxia/*complications
Atherosclerosis/complications
Biomarkers
Cells, Cultured
DNA Damage
Disease Models, Animal
Epithelial Cells/ultrastructure
Fibrosis
Humans
Ischemia/*complications
Lipid Peroxidation
Male
Myocytes, Smooth Muscle/ultrastructure
Nerve Degeneration
*Oxidative Stress
Prostate/*anatomy & histology/*cytology
Rabbits
Stromal Cells/ultrastructure
Urinary Bladder Neck Obstruction/complications
Biomarkers

Figure

• 

  Fig. 1 Human prostate SMCs (A), ECs (B), and SCs (C) exhibited explicit reactions to hypoxia and oxidative stress. Lipid peroxidation was more prevalent in SMCs, whereas ECs appeared more susceptible to protein oxidation. Hypoxia caused lipid peroxidation in SMCs and protein oxidation in ECs. Oxidative stress led to protein oxidation and lipid peroxidation in SMCs, ECs, and SCs. Protein oxidation and lipid peroxidation suggest damage to protein- and lipid-containing structures of the cells, respectively. SMC, smooth muscle cell; EC, epithelial cell; SC, stromal cell; AOPP, advanced oxidation protein product; MDA, malondialdehyde. *Represent significance versus control.

• 

  Fig. 2 Nonconforming oxygen tension led to widespread DNA damage in cultured human prostatic cells. Both hypoxia and oxidative stress induced DNA damage in SMCs (A), ECs (B), and SCs (C), characterized by a significant increase in 8-hydroxy-2'-deoxyguanosine levels. SMC, smooth muscle cell; EC, epithelial cell; SC, stromal cell. *Represent significance versus control.

• 

  Fig. 3 Hypoxia and oxidative stress altered human prostate SMC structure. (A) TEM of cultured cell samples from the normoxia group showed distinct cell membrane, normal cytoplasmic structures, mitochondria with well-defined membrane and cristae, and normal ER. (B) Cell samples from the hypoxia group showed twisted cell membrane, distorted mitochondria with deformed membranes, swollen deformed ER, and cytoplasmic accumulation of glycogen. (C) Cell samples from the oxidative stress group showed irregular cell membrane and degradation of cytoplasmic structures such as swollen mitochondria with deformed or lost cristae, enlarged and partially degraded ER, and cytoplasmic accumulation lysosomes. White arrows point to mitochondria, black arrows point to ER, curved white arrows points to lysosomes, curved black arrows point to cell membrane, and double arrows point to glycogen. ER, endoplasmic reticulum; SMC, smooth muscle cell; TEM, transmission electron microscopy.

• 

  Fig. 4 Markers of oxidative damage in chronic rabbit prostate ischemia. Prostatic tissues from the ischemia group showed significant protein oxidation (A) and lipid peroxidation (B), characterized by significant increases in MDA and AOPP levels versus the sham group. AOPP, advanced oxidation protein product; MDA, malondialdehyde. *Represent significance versus control.

• 

  Fig. 5 Masson's trichrome staining of rabbit ischemic prostate tissues (×40) showed stromal thickening with diffuse fibrosis, decreased smooth muscle fibers, distorted glands with flattened epithelium lining, and large intraluminal spaces compared to prostatic tissues from the sham group (×40).

• 

  Fig. 6 Transmission electron microscopy of chronically ischemic rabbit prostate showed thickened epithelium with degraded or totally lost desmosomes; disruption of cell to cell junctions; disrupted and twisted muscle cells surrounded by collagen; collagen invasion of smooth muscle cells; nuclear deformation; loss of nuclear membrane; and collagen invasion of the nucleus. White arrows point to desmosome and epithelial cell to cell junctions. Curved arrows point to smooth muscle cells showing collagen accumulation and collagen invasion of smooth muscle cells in the ischemic sample. Black arrows point to nucleus showing collagen invasion of the nucleus and loss of nuclear membrane in the ischemic sample.

• 

  Fig. 7 Marked changes in cellular organelles including swollen mitochondria with irregular membrane, loss of mitochondrial membrane, disrupted mitochondrial granules, and sporadic vacuolization were present in the chronically ischemic rabbit prostate. Mitochondrial structural damage in the ischemic prostate was associated with degenerating nerve bundles surrounded by dense collagen fibers. White arrows point to mitochondria, black arrows point to the nerve bundles, and curved arrows point to collagen fiber bundles around the nerves.

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