Phenotypic characterization of human prostatic stromal cells in primary cultures derived from human tissue samples

Abstract

Abstract.Emerging evidence has shown that the tumor microenvironment plays a crucial role in prostate cancer (PCa) development and progression. However, the mechanism(s) through which stromal cells regulate epithelial cells and the differences among prostatic stromal cells of different histological/pathological origin in PCa progression remain unclear. Therefore, it is necessary to characterize the stromal cell populations present in benign prostatic hyperplasia (BPH) and PCa. To this end, we used cultures from stromal cells obtained from BPH-derived (15 cases) and PCa-derived (30 cases) primary cultures. In culture, stromal cells are a mixture of fibroblasts, myofibroblasts (MFs) and muscle cells. Fibroblasts are characterized for the expression of vimentin, MFs for the co-expression of α-smooth muscle actin (α-SMA) and vimentin, whereas muscle cells for the expression of α-SMA and desmin. Fibroblasts were present in large amounts in the BPH-compared to the PCa-derived cultures, whereas MFs were more representative of PCa-as opposed to BPH-derived cultures. Some α-SMA-positive cells retained the expression of basal cytokeratin K14. This population was defined as myoepithelial cells and was associated with senescent cultures. The percentage of MFs was higher in high-grade compared to moderate-and low-grade PCa-derived cultures, whereas the number of myoepithelial cells was lower in high-grade compared to moderate-and low-grade PCa-derived cultures. In addition, we analyzed the expression of p75NTR, as well as the expression of matrix metalloproteinase (MMP)-2, MMP-9 and tissue inhibitors of MMPs (TIMPs). p75NTR expression was elevated in the stromal cultures derived from PCa compared to those derived from BPH and in cultures derived from cases with Gleason scores ≥7 compared to those derived from cases with Gleason scores <7, as well as in cultures with a high concentration of MFs compared to those with a high concentration of fibroblasts. MMP-2 was secreted by all primary cultures, whereas MMP-9 secretion was observed only in some PCa-derived stromal cells, when the percentage of MFs was significantly higher compared to BPH-derived cultures. TIMP1, TIMP2 and TIMP3 were secreted in elevated amounts in the BPH-compared to the PCa-derived stromal cultures, suggesting the differential regulation of extracellular matrix (ECM) degradation. When we used 22rv1 and PC3 PCa xenograft models for the isolation and characterization of murine cancer-associated fibroblasts (CAFs) we noted that the angiogenic wave was concurrent with the appearance of a reactive stroma phenotype, as determined by staining for α-SMA, vimentin, tenascin, calponin, desmin and Masson's trichrome. In conclusion, MF stromal cells from PCa participate in the progression and metastasis of PCa, modualting inflammation, angiogenesis and epithelial cancer cell proliferation.

Structure and Function of a Prostate Cancer Dissemination–Permissive Extracellular Matrix

“…Additionally, the percentage of myofibroblasts in high-grade prostate cancer derived primary cultures was higher than in moderate and low grade cancer (41), confirming the importance of CAFs in tumor formation and progression. Prostate cancer is characterized by a reactive stroma that is enriched with fibroblasts and myoblasts (42).…”

E‐cadherin is downregulated in benign prostatic hyperplasia and required for tight junction formation and permeability barrier in the prostatic epithelial cell monolayer

“…The stromal cells from BPH tissues may be characterized by properties that allow the infiltration and retention of secreted proteins that are not evident in prostate cancer stromal cells. Others have shown that BPH stromal cells are more fibroblastic, while prostate cancer stromal cells are more myofibroblastic . Additionally, BPH and prostate cancer typically occur in different anatomic locations, which may also play a role in the presence of secreted proteins in BPH stroma.…”

TRAF6 regulates proliferation of stromal cells in the transition and peripheral zones of benign prostatic hyperplasia via Akt/mTOR signaling

“…Anti α‐SMA and anti‐vimintin were used to determine the stromal cell populations by Immunofluorescence. After three to four passages, a homogeneous stromal cell population was established …”