Tumor formation of prostate cancer cells influenced by stromal cells from the transitional or peripheral zones of the normal prostate

Targeting tumor and bone microenvironment: Novel therapeutic opportunities for castration-resistant prostate cancer patients with bone metastasis

Despite standard hormonal therapy that targets the androgen receptor (AR) attenuates prostate cancer (PCa) effectively in the initial stage, the tumor ultimately converts to castration-resistant prostate cancer (CRPC), and the acquired resistance is still a great challenge for the management of advanced prostate cancer patients. The tumor microenvironment (TME) consists of multiple cellular and noncellular agents is well known as a vital role during the development and progression of CRPC by establishing communication between TME and tumor cells. Additionally, as primary prostate cancer progresses towards metastasis, and CRPC always experiences bone metastasis, the TME is conducive to the spread of tumors to the distant sits, particularly in bone. In addition, the bone microenvironment (BME) is also closely related to the survival, growth and colonization of metastatic tumor cells. The present review summarized the recent studies which mainly focused on the role of TME or BME in the CRPC patients with bone metastasis, and discussed the underlying mechanisms, as well as the potential therapeutic values of targeting TME and BME in the management of metastatic CRPC patients.

Efficacy and safety of moxibustion for benign prostatic hyperplasia: A protocol of systematic review and meta-analysis

BACKGROUND

Benign prostatic hyperplasia (BPH) is a non-malignant enlargement of the prostate gland that is common in older men. The clinical manifestations of BPH are frequent urination, urgency, incomplete dribbling of urine, and urinary retention. Moxibustion, as a convenient, safe and effective method, has been widely applied in the clinical treatment of BPH. The study aim to assess the efficacy and safety of moxibustion for BPH.

METHODS

The following electronic databases will be searched regardless of language and publication status: Pubmed, MEDLINE, EMBASE, China Biomedical Database, China National Knowledge Infrastructure, VIP Database, and Wanfang Database, to select studies that meet the requirements. The study will consist of a prospective randomised controlled clinical trials (RCTs) of moxibustion in the treatment of BPH, language of publication does not have barrier of blinding or restrictions, adverse events will be assessed and reported for safety assessment. Two reviewers will independently conduct and screen all included studies and the meta-analysis will be performed with RevMan V5.3.

RESULTS

The study will provide a high-quality convincing assessment of efficacy and safety of moxibustion for BPH.

CONCLUSION

The conclusion of this study will provide the latest evidence for judging whether moxibustion is effective and safe in the treatment of BPH.

TRIAL REGISTRATION NUMBER

INPLASY2021120021.

LMO2 upregulation due to AR deactivation in cancer-associated fibroblasts induces non-cell-autonomous growth of prostate cancer after androgen deprivation

The androgen receptor (AR) is expressed in prostate fibroblasts in addition to normal prostate epithelial cells and prostate cancer (PCa) cells. Moreover, AR activation in fibroblasts dramatically influences prostate cancer (PCa) cell behavior. Androgen deprivation leads to deregulation of AR downstream target genes in both fibroblasts and PCa cells. Here, we identified LIM domain only 2 (LMO2) as an AR target gene in prostate fibroblasts using ChIP-seq and revealed that LMO2 can be repressed directly by AR through binding to androgen response elements (AREs), which results in LMO2 overexpression after AR deactivation due to normal prostate fibroblasts to cancer-associated fibroblasts (CAFs) transformation or androgen deprivation therapy. Next, we investigated the mechanisms of LMO2 overexpression in fibroblasts and the role of this event in non-cell-autonomous promotion of PCa cells growth in the androgen-independent manner through paracrine release of IL-11 and FGF-9. Collectively, our data suggest that AR deactivation deregulates LMO2 expression in prostate fibroblasts, which induces castration resistance in PCa cells non-cell-autonomously through IL-11 and FGF-9.

5-ARI induces autophagy of prostate epithelial cells through suppressing IGF-1 expression in prostate fibroblasts

Objectives

5α‐reductase inhibitor (5‐ARI) is a commonly used medicine in the treatment of lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH). Our study mainly focuses on the mechanism of BPH development after 5ARI treatment.

Materials and Methods

Prostate specimens from patients were collected. Insulin‐like growth factor 1 (IGF‐1), Beclin‐1, LC3 levels, was analysed by immunohistochemistry. The role IGF‐1 on autophagic flux in prostate epithelial cells was studied. Additionally, effect of autophagy on recombinant grafts consisting of prostate stromal and epithelial cells in nude mice was investigated.

Results

We demonstrated that IGF‐1 expression is down‐regulated in prostate fibroblasts after long‐term 5‐ARI application. A decrease in IGF‐1 levels was found to activate autophagic flux through the mTOR pathway in prostate epithelial cells, while the inhibition of IGF‐1 receptor function induced autophagy in prostate epithelial cells. In addition, we revealed that blocking autophagic flux initiation can reduce the volume of recombinant grafts in vivo. Finally, our findings suggest that long‐term 5‐ARI application reduces IGF‐1 secretion by prostatic stromal cells, thereby inducing autophagy of prostatic epithelial cells, which is one of the mechanisms underlying BPH pathogenesis and progression.

Conclusions

Focusing on the autophagy induced by low levels of IGF‐1 in prostatic epithelial cells, after elucidating AR signalling impairment of prostate stromal cells, might provide a novel strategy for the treatment and prevention of BPH development.

Deregulation of ATG9A by impaired AR signaling induces autophagy in prostate stromal fibroblasts and promotes BPH progression

The activation of androgen receptor (AR) signaling plays an essential role in both prostate stromal cells and epithelial cells during the development of benign prostatic hyperplasia (BPH). Here we demonstrated that androgen ablation after 5α-reductase inhibitor (5-ARI) treatment induced autophagy in prostate stromal fibroblasts inhibiting cell apoptosis. In addition, we found that ATG9A expression was increased after androgen ablation, which facilitated autophagic flux development. Knockdown of ATG9A not only inhibited autophagy notably in prostate stromal fibroblasts, but also reduced the volumes of prostate stromal fibroblast and epithelial cell recombinant grafts in nude mice. In conclusion, our findings suggested that ATG9A upregulation after long-term 5-ARI treatment constitutes a possible mechanism of BPH progression. Thus, combined treatment with 5-ARI and autophagy inhibitory agents would reduce the risk of BPH progression.

LIM domain only 2 over-expression in prostate stromal cells facilitates prostate cancer progression through paracrine of Interleukin-11

Mechanisms of stromal-epithelial crosstalk are essential for Prostate cancer (PCa) tumorigenesis and progression. Peripheral zone of the prostate gland possesses a stronger inclination for PCa than transition zone. We previously found a variety of genes that differently expressed among different prostate stromal cells, including LIM domain only 2 (LMO2) which highly expressed in peripheral zone derived stromal cells (PZSCs) and PCa associated fibroblasts (CAFs) compared to transition zone derived stromal cells (TZSCs). Studies on its role in tumors have highlighted LMO2 as an oncogene. Herein, we aim to study the potential mechanisms of stromal LMO2 in promoting PCa progression. The in vitro cells co-culture and in vivo cells recombination revealed that LMO2 over-expressed prostate stromal cells could promote the proliferation and invasiveness of either prostate epithelial or cancer cells. Further protein array screening confirmed that stromal LMO2 stimulated the secretion of Interleukin-11 (IL-11), which could promote proliferation and invasiveness of PCa cells via IL-11 receptor α (IL11Rα) – STAT3 signaling. Moreover, stromal LMO2 over-expression could suppress miR-204-5p which was proven to be a negative regulator of IL-11 expression. Taken together, results of our study demonstrate that prostate stromal LMO2 is capable of stimulating IL-11 secretion and by which activates IL11Rα – STAT3 signaling in PCa cells and then facilitates PCa progression. These results may make stromal LMO2 responsible for zonal characteristic of PCa and as a target for PCa microenvironment-targeted therapy.

Human Stromal Cells in the Peripheral Zone of the Prostate Promote Tumorigenesis of Prostatic Cancer Stem Cells through Up-regulation of C-Kit Expression

Objective: Most prostate cancers originate from the prostatic peripheral zone (PZ). We tested the hypothesis that the stromal cells from PZ and transitional zone (TZ) have differential effects on the ability of tumorigenesis.

Methods: Stromal cells isolated from the PZ and TZ of normal human prostates mixed with DU145 cells subcutaneously injected into athymic nude mice. The volume and weight of tumors was measured and analyzing the ability of purified DU145 cells isolated from the tumors to migrate and proliferate. The expression patterns of stem cell-specific genes of these DU145 cells were examined. The C-Kit inhibitor, imatinib mesylate, was administrated to confirm the effect of stromal cells on the tumorigenesis.

Results: The volume and weight of tumors were significantly higher in mice transplanted with DU145 and stromal cells from PZ. In contrast, the data was significantly lower with DU145 and stromal cells from TZ than DU145 alone. The purified DU145 cells isolated from the tumors with DU145 and stromal cells in PZ had increased ability to migrate and proliferate, and had increased expression of C-Kit. These effects of the stromal cells in the PZ on DU145 cells could be blocked using imatinib mesylate.

Conclusions: Human stromal cells in the PZ promote the in vivo tumorigenesis of DU145 through up-regulating C-Kit; in contrast, the stromal cells in the TZ inhibit it through down-regulating the expression of C-Kit. The model will be useful for understanding the mechanisms by which the prostatic stem cell niche controls the tumorigeneis of prostatic cancer stem cells.

Androgen receptors expressed by prostatic stromal cells obtained from younger versus older males exhibit opposite roles in prostate cancer progression

Aging is a major risk factor for prostate cancer (PCa), and prostatic stromal cells may also promote PCa progression. Accordingly, stromal cells do not equally promote PCa in older males and younger males. Therefore, it is also possible that the expression of androgen receptors (ARs) by prostatic stromal cells in older versus younger males plays different roles in PCa progression. Using a gene knockdown technique and coculture system, we found that the knockdown of the AR in prostatic stromal cells obtained from younger males could promote the invasiveness and metastasis of cocultured PC3/LNCaP cells in vitro. By contrast, the invasiveness and metastasis of LNCaP cells was inhibited when cocultured with prostatic stromal cells from older males that when AR expression was knocked down. Moreover, after targeting AR expression with small hairpin RNA (shRNA), matrix metalloproteinase (MMP) expression in stromal cells was observed to increase in the younger group, but decreased or remained unchanged in the older group. One exception, however, was observed with MMP9. In vivo, after knocking down AR expression in prostatic stromal cells, the incidence of metastatic lymph nodes was observed to increase in the younger age group, but decreased in the older age group. Together, these data suggest that the AR in prostatic stromal cells played opposite roles in PCa metastasis for older versus younger males. Therefore, collectively, the function of the AR in prostatic stromal cells appears to change with age, and this may account for the increased incidence of PCa in older males.

Expression analysis of thrombospondin 2 in prostate cancer and benign prostatic hyperplasia

Thrombospondin 2 (TSP2) is a protein with important roles in different tumor types, mainly related to tumor inhibition. However, there are limiting data regarding TSP2 in prostate cancer (PCa) and benign prostatic hyperplasia (BPH). We aimed to investigate TSP2 transcript and protein expression in tumoral and non-tumoral prostate tissues and cell lines, and its implications for PCa diagnosis and progression. TSP2 transcript expression was evaluated by real time PCR in PCa and BPH tissue samples and in tumoral and non-tumoral cell lines. TSP2 protein expression analysis was conducted by immunohistochemistry in a tissue microarray (TMA) containing PCa and BPH tissue samples. TSP2 transcript was down-regulated in PCa tissue samples and cell lines, when compared to BPH and non-tumoral samples (P<0.01). Receiver Operating Curve (ROC) analysis demonstrated that TSP2 transcript levels can better distinguish PCa from BPH tissue samples (P<0.01) than serum PSA levels (P=0.299). TSP2 protein expression has been observed in the cytoplasm of both PCa and BPH epithelial and stromal compartments. TSP2 stromal staining scores were significantly lower in PCa than in BPH tissues (P<0.01), while similar TSP2 epithelial staining patterns were observed in both diseases. Notably, the TSP2 epithelial staining score was significantly correlated to vascular invasion and biochemical recurrence in PCa tissue samples (P<0.05). Our data indicate that TSP2 is down-regulated at PCa tissues and cell lines, especially at stroma compartment, which could be related to PCa progression. TSP2 levels could potentially be applied for differential PCa and BPH diagnosis.

Distinct function of estrogen receptor α in smooth muscle and fibroblast cells in prostate development

Estrogen signaling, through estrogen receptor (ER)α, has been shown to cause hypertrophy in the prostate. Our recent report has shown that epithelial ERα knockout (KO) will not affect the normal prostate development or homeostasis. However, it remains unclear whether ERα in different types of stromal cells has distinct roles in prostate development. This study proposed to elucidate how KO of ERα in the stromal smooth muscle or fibroblast cells may interrupt cross talk between prostate stromal and epithelial cells. Smooth muscle ERαKO (smERαKO) mice showed decreased glandular infolding with the proximal area exhibiting a significant decrease. Fibroblast ERαKO mouse prostates did not exhibit this phenotype but showed a decrease in the number of ductal tips. Additionally, the amount of collagen observed in the basement membrane was reduced in smERαKO prostates. Interestingly, these phenotypes were found to be mutually exclusive among smERαKO or fibroblast ERαKO mice. Compound KO of ERα in both fibroblast and smooth muscle showed combined phenotypes from each of the single KO. Further mechanistic studies showed that IGF-I and epidermal growth factor were down-regulated in prostate smooth muscle PS-1 cells lacking ERα. Together, our results indicate the distinct functions of fibroblast vs. smERα in prostate development.

The differential effects of prostate stromal cells derived from different zones on prostate cancer epithelial cells under the action of sex hormones

It is well known that prostate cancer (PCa) occurs predominantly in the peripheral zone (PZ), whereas benign prostatic hyperplasia (BPH) typically develops in the transition zone. To identify possible mechanisms underlying zonal differences, we compared the effects of prostate stromal cells derived from the peripheral zone (PZsc) and the transition zone (TZsc) on a PCa epithelial cell line (PC3) in the presence of sex hormones. First, we observed that androgen receptor (AR) mRNA was more highly expressed in PZsc than TZsc when the cells were treated with dihydrotestosterone (DHT) and β-oestradiol (E2) (P<0.05). By ELISA, we looked for differences in the secretion of peptide growth factors from PZsc and TZsc. We found that keratinocyte growth factor (KGF) secretion increased with increasing concentrations of DHT (P<0.01) and was higher in PZsc than TZsc. Under treatment with DHT plus E2, PZsc secreted more transforming growth factor-β1 (TGF-β1) than TZsc, but this pattern was reversed when the cells were treated with E2 only. With increasing concentrations of DHT, insulin-like growth factor-1 (IGF-1) secretion increased in PZsc but decreased in TZsc. To further characterize the effects of PZsc and TZsc on PC3 cells, we developed a coculture model and performed MTT assays, Western blot analysis and real-time RT-PCR. We found that PZsc promoted PC3 cell proliferation and progression better than TZsc, particularly when treated with 10 nmol l(-1) DHT plus 10 nmol l(-1) E2. In conclusion, our data suggest that PZsc may have a greater capacity to induce PCa development and progression than TZsc via growth factors regulated by sex hormones. These findings provide possible mechanisms underlying zonal differences in prostate diseases, which may aid the search for novel therapeutic targets for PCa.

Differences in phenotype and gene expression of prostate stromal cells from patients of varying ages and their influence on tumour formation by prostate epithelial cells

Prostate cancer (PCa) is an age-related disease, and the stromal microenvironment plays an important role in prostatic malignant progression. However, the differences in prostate stromal cells present in young and old tissue are still obscure. We established primary cultured stromal cells from normal prostatic peripheral zone (PZ) of donors of varying ages and found that cultured stromal cells from old donors (PZ-old) were more enlarged and polygonal than those from young donors (PZ-young). Furthermore, based on immunocytochemical and ultrastructural analysis, the components of stromal cells changed from a majority of fibroblasts to a mixture of fibroblasts and myofibroblasts with increasing donor age. Using a three-dimensional in vitro culture system, we found that PZ-old stromal cells could enhance the proliferation, migration and invasion of cocultured benign BPH-1 and PC-3 cells. Using an in vivo tissue recombination system, we also found that PZ-old stromal cells are more effective than PZ-young cells in promoting tumour formation by BPH-1 cells of high passage (>100) and PC-3 cells. To probe the possible mechanism of these effects, we performed cDNA microarray analysis and profiled 509 upregulated genes and 188 downregulated genes in PZ-old cells. Among the changed genes, we found genes coding for a subset of paracrine factors that are capable of influencing adjacent epithelial cells; these include hepatocyte growth factor (HGF), fibroblast growth factor 5 (FGF5), insulin-like growth factor 2 (IGF2), insulin-like growth factor-binding protein 4 (IGFBP4), IGFBP5 and matrix metallopeptidase 1 (MMP1). Changes in the expression of these genes were further confirmed by quantitative real-time polymerase chain reaction (PCR), Western blotting and enzyme-linked immunosorbent assays. Overall, our findings indicate that stromal cells from prostate PZ of old donors are more active than similar cells from young donors in promoting the malignant process of adjacent epithelial cells. This finding hints at a new potential strategy for the prevention of PCa.

Characterization and functional role of the stroma compartment in prostate tumors

Evaluation of: Dakhova O, Ozen M, Creighton CJ et al.: Global gene expression analysis of reactive stroma in prostate cancer. Clin. Cancer Res. 15, 3979–3989 (2009). Prostate tumors are composed of many cell types, yet the biological significances of the different nonepithelial cells have been largely overlooked. According to recent studies, however, the stroma, which constitutes a substantial part of the tumor volume, plays an important role during the initiation, progression, metastasis and metastatic growth of prostate cancers. To explore this further, Dakhova and co-workers compared gene expression in laser microdissected normal peripheral zone stroma with stroma in peripheral zone cancers (only those with reactive stroma grade 3). A total of 544 genes were upregulated and 606 genes downregulated in tumor stroma. The cancer stroma showed signs of formation of nerves, increased number of stem cells, and responses to DNA damage. Further studies are needed to explore the functional consequences of this, particularly the role of nerves. If these stroma changes can be used as prognostic markers, as targets for therapy, and if similar changes occur in metastases also need to be explored.

Human prostate fibroblasts induce growth and confer castration resistance and metastatic potential in LNCaP Cells

BACKGROUND

The tumor microenvironment is important for progressive and metastatic disease.

OBJECTIVE

To study the hypothesis that prostate fibroblasts have differential ability to induce castration-resistant prostate cancer (PCa) and metastatic progression and whether this effect might vary depending on the zonal origin of the fibroblast.

DESIGN, SETTING, AND PARTICIPANTS

Human prostate fibroblasts from the peripheral (PZ), transition (TZ) and central (CZ) zones of radical prostatectomy specimens (n=13) were isolated and compared for their ability to promote androgen independence and metastatic progression in androgen-responsive PCa lymph node carcinoma of the prostate (LNCaP) cells in vivo.

INTERVENTIONS

By coinoculating marginally tumorigenic LNCaP cells with PZ or TZ and by altering host hormonal milieu, a series of tumorigenic and metastatic LNCaP epithelial sublines-P4, P4-2 (derivatives from interaction with PZ), T4, and T4-2 (derivatives from interaction with TZ)-were established and characterized.

MEASUREMENTS

In vivo and in vitro evaluation of induction of tumor growth and metastatic potential.

RESULTS AND LIMITATIONS

1) LNCaP sublines were permanently altered in their cytogenetic and biologic profiles after cellular interaction with prostate stromal fibroblasts. LNCaP sublines grew faster under anchorage-dependent and -independent conditions, expressed 1-12-fold more prostate-specific antigen in vitro than LNCaP cells, and gained metastatic potential; 2) zonal differences of stromal fibroblasts in their ability to induce the growth and progression of LNCaP tumors as xenografts in mice may exist but need further analysis; 3) PZ-conditioned medium induced more anchorage-independent growth of LNCaP cells in vitro. TZ had a higher growth rate and were more sensitive to dihydrotestosterone.

CONCLUSIONS

We demonstrate that prostate fibroblasts have growth inductive potential on PCa cells and affect their subsequent progression to castration resistance and development of a metastatic phenotype.