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.     

Ursolic acid,a naturally occurring triterpenoid,demonstrates anticancer activity on human prostate cancer cells

Purpose Glucocorticoids are widely used as adjuvant therapy in hormonal refractory prostate cancer; their therapeutic role, however, remains unclear. Ursolic acid, a natural triterpene, structurally similar to dexamethasone, exhibits antitumor effects in various cell types. Our main objective was to investigate the effects of ursolic acid on cell viability, apoptosis and bcl-2 protein, in human hormone refractory and androgen-sensitive prostate cancer cells. Methods The ursolic acid-induced changes in cell viability, apoptosis and bcl-2 protein were examined in human hormone refractory prostate cancer PC-3 cells and androgen-sensitive LNCaP cells, by MTT assay, flow cytometry and western blot analysis, respectively. Results Ursolic acid inhibited significantly the cell viability and induced apoptosis in PC-3 cells at 55 μM and in LNCaP cells at 45 μM associated with a downregulation of bcl-2 protein. Conclusions The antiproliferative and apoptotic effects of ursolic acid in PC-3 and LNCaP cells implicate its potential therapeutic use for the treatment of hormone refractory and androgen-sensitive prostate cancer. The downregulation of bcl-2 may be one of the molecular mechanisms via which it induces apoptosis in PC-3 and LNCaP cells. Financial support by a grant PAVE from the General Secretariat of Research and Technology in cooperation with the company ELPEN.     

Assessing the therapeutic and toxicological effects of cesium chloride following administration to nude mice bearing PC-3 or LNCaP prostate cancer xenografts

Purpose The purpose of this study was to assess the therapeutic and toxicological effects of cesium chloride (CsCl) administration in mice bearing prostate cancer tumors. Methods Three CsCl dose titration studies were completed in tumor-bearing and non-tumor-bearing athymic nude mice. All mice were administered either vehicle (controls), 150, 300, 600, 800, 1,000, or 1,200 mg/kg of CsCl once daily by oral gavage for 30 consecutive days. Body mass was measured daily, food and water consumption were measured every 2 days, and tumor volume was measured twice weekly. Histopathological analysis was conducted on tissues collected from each of the studies. Serum AST/ALT and creatinine were also measured. Results Administration of 800–1,200 mg/kg CsCl reduced PC-3 tumor growth but had no effect on LNCaP tumors. Administration of 800–1,200 mg/kg CsCl also resulted in increased water consumption, bladder crystal development, and higher prevalence of cardiac fibrin clots. An observed loss in body mass was dependent on the xenograft type and concentration of CsCl administered. CsCl did not affect serum AST/ALT and creatinine levels. Conclusions CsCl may have a therapeutic effect against prostate cancer, but one cannot overlook the acute toxicities also described.     

The Effect of Curcumin on Proliferation and Apoptosis in LNCaP Prostate Cancer Cells

OBJECTIVE To observe the effect of curcumin on proliferation and apop-tosis in the prostate cancer LNCaP cell line. METHODS The AXSYMTM system luciferase method was used to examine the effect of various concentratious of curcumin on the content of prostate specific antigen (PSA) in prostate cancer LNCaP cells. A pGL3-PSA luciferase expression vector, containing 640 bp DNA of the PSA gene 5' -promoter region was constructed and transfected into the LNCaP cells with lipofectin. By measuring luciferase activity, the effect of 10 μmol/L, 20 μmol/L, 30 and 40 μmol/L curcumin on the promoter was studied. Effects on cell growth and apoptosis were analyzed by microscopy, the MTT colorimetric assay and flow cytometry. Western-blotting was used to measure expression of the androgen receptor (AR) in the LNCaP cells treated with different concentrations of curcumin. RESULTS The results showed that the expression of PSA was inhibited as curcumin reduced the activity of luciferase. Curcumin also caused a sigificant concentration-dependent decrease in AR expession measured by Western -blotting. Cell growth was inhibited and apoptosis was induced. CONCLUSION By inhibiting AR expression, curcumin reduced the function of the PSA promoter and inhibited PSA protein expression. Curcumin decreased the cellular proliferation and induced apoptosis in LNCaP cells in a concention-dependent manner.     

Differential regulation of metabolic pathways by androgen receptor (AR) and its constitutively active splice variant,AR-V7, in prostate cancer cells

Metastatic prostate cancer (PCa) is primarily an androgen-dependent disease, which is treated with androgen deprivation therapy (ADT). Tumors usually develop resistance (castration-resistant PCa [CRPC]), but remain androgen receptor (AR) dependent. Numerous mechanisms for AR-dependent resistance have been identified including expression of constitutively active AR splice variants lacking the hormone-binding domain. Recent clinical studies show that expression of the best-characterized AR variant, AR-V7, correlates with resistance to ADT and poor outcome. Whether AR-V7 is simply a constitutively active substitute for AR or has novel gene targets that cause unique downstream changes is unresolved. Several studies have shown that AR activation alters cell metabolism. Using LNCaP cells with inducible expression of AR-V7 as a model system, we found that AR-V7 stimulated growth, migration, and glycolysis measured by ECAR (extracellular acidification rate) similar to AR. However, further analyses using metabolomics and metabolic flux assays revealed several differences. Whereas AR increased citrate levels, AR-V7 reduced citrate mirroring metabolic shifts observed in CRPC patients. Flux analyses indicate that the low citrate is a result of enhanced utilization rather than a failure to synthesize citrate. Moreover, flux assays suggested that compared to AR, AR-V7 exhibits increased dependence on glutaminolysis and reductive carboxylation to produce some of the TCA (tricarboxylic acid cycle) metabolites. These findings suggest that these unique actions represent potential therapeutic targets.     

PC-1基因表达对前列腺癌细胞迁移能力的影响

背景与目的:PC-1基因在雄激素非依赖和高转移能力的前列腺癌C4-2细胞中高表达,在雄激素依赖及不转移的前列腺癌LNCaP细胞中低表达。本实验旨在研究PC-1对前列腺癌细胞迁移能力的影响。方法:构建PC-1稳定高表达的LNCaP细胞株和反义核酸调低内源性PC-1表达的C4-2细胞株。利用体外迁移系统检测PC-1表达对LNCaP和C4-2细胞迁移运动能力的影响。结果:体外迁移实验表明稳定转染提高PC-1的表达水平并未使LNCaP迁移细胞数增多(P>0.05),而反义核酸降低PC-1表达则使C4-2迁移细胞数降低(P<0.05)。PC-1蛋白水平升高不能提高LNCaP细胞迁移能力,但降低内源性PC-1表达则使C4-2细胞迁移能力明显降低。结论:PC-1可能在前列腺癌细胞侵袭过程中起一定作用。     

帕米磷酸二钠及埃本磷酸二钠对前列腺癌细胞系DU145、LNCaP体外生长的抑制作用

目的　观察帕米磷酸二钠 (PAM )及埃本磷酸二钠 (IBN )对体外培养的前列腺癌细胞系DU 14 5、LNCaP生长的抑制作用 ,探讨双磷酸盐类药物抑制前列腺癌细胞生长的机制。方法　采用MTT法检测不同剂量的PAM、IBN对DU 14 5、LNCaP细胞系生长的影响 ,并计算 2种药物的IC50 值 ,应用流式细胞仪检测DNA含量以探讨双磷酸盐类药物的作用机制。结果　PAM、IBN对前列腺癌DU 14 5、LNCaP细胞系的生长均有抑制作用 ,抑制效应与药物剂量、作用时间成正比 ,15 0 μg/mlPAM和 10 0 μg/mlIBN作用 72h后 ,2种细胞的生存率均低于 40 .0 0 % (P <0 .0 5 )。根据IC50 值可知IBN对前列腺癌细胞的抑制作用比PAM强。结论　PAM、IBN对体外生长的前列腺癌细胞系DU 14 5、LNCaP产生剂量、时间依赖性的抑制作用 ,其抑制细胞的作用机制为促进癌细胞凋亡和干扰DNA合成。