Antisense Bcl-2 sensitizes prostate cancer cells to radiation

BACKGROUND: Bcl-2 is anti-apoptotic and overexpression is associated with prostate tumor aggressiveness. We hypothesized that Bcl-2 has a role in prostate cancer radiation (RT) response. The relationship of Bcl-2 expression in four prostate cancer cell lines, and the effect of modulating expression with a Bcl-2 antisense oligonucleotide (G3139, Genasense, oblimersen sodium, Genta Incorporated), to RT was examined. METHODS: The four cell lines studied were LNCaP (wild type-p53), PC3 (p53 null), Bcl-2 stably transfected LNCaP (LNCaP-BST), and Bcl-2 stably transfected PC3 (PC3-BST) cells. Cells were treated with antisense (AS) Bcl-2 alone or with RT (2-6 Gy). Following RT, cells were processed at 3-6 hr for Western blots, 18 hr for Annexin V staining and flow cytometric analysis, 24 hr for caspases 3+7 quantification by fluorometric assay, and immediately for clonogenic survival. RESULTS: AS caused a significant reduction in Bcl-2 expression in all cell lines. P53 expression was elevated following RT treatment in LNCaP and LNCaP-BST cells. P21 was increased by RT treatment in all cell lines. AS caused a significant increase in caspase 3+7 activity over the mismatch (MM) controls in all cell lines. When AS was combined with RT, caspase 3+7 activity was further increased significantly over all other groups in all cell lines. Moreover, AS+RT resulted in significantly reduced clonogenic survival over MM+RT, which was dampened in the Bcl-2 overexpressing lines. CONCLUSIONS: To our knowledge, these data demonstrate for the first time that a Bcl-2 specific AS oligonucleotide sensitizes prostate cancer cells to RT. p53 is not required for this effect.     

Localization of the human prostatic secretory protein PSP94 and its mRNA in the epithelial cells of the prostate

The histologic distribution of a prostatic secretory protein of 94 amino acids (PSP94) and its mRNA were examined simultaneously by conventional immunohistochemistry and in situ hybridization histochemistry. The results show localization of immunoreactive PSP94 and its mRNA in the epithelial cells of the prostate gland, thus providing strong evidence of PSP94 synthesis in these cells. Preliminary analysis of PSP94 by radioimmunoassay and of its mRNA by Northern blot analysis indicates that PSP94 biosynthesis in pathologic prostatic tissues is variable. The value of PSP94 as a marker of prostate gland secretory activity is discussed.     

Characterization and localization of cysteine-rich secretory protein 3 (CRISP-3) in the human male reproductive tract

Mammalian members of the cysteine-rich secretory protein (CRISP) family are expressed predominantly in the male reproductive tract and are implicated in the process of reproduction from spermiogenesis, posttesticular sperm maturation, and capacitation to oocyte-sperm fusion, and possibly also penetration of the zona pellucida. Rodents express only 2 CRISPs (CRISP-1 and CRISP-2) in their male reproductive system, whereas humans and horses express an additional third member named CRISP-3. We have previously demonstrated that this protein is present in human seminal plasma as well as in other exocrine secretions, in blood plasma, and in neutrophilic granulocytes. To characterize the protein in seminal plasma and localize the production of CRISP-3 in the human male reproductive tract, we performed immunoblotting and enzyme-linked immunosorbent assay measurements of seminal plasma and immunohistochemistry and in situ hybridization of tissue specimens. We were able to show that human CRISP-3 is a quantitatively minor seminal plasma protein not associated with prostasomes. Furthermore, CRISP-3 expression was found in the secretory epithelium throughout the male genital tract, with particularly high expression in the cauda epididymis and ampulla vas deferens. Examination of seminal plasma from vasectomized males indicates that organs downstream of the epididymis are probably the major sources of seminal plasma CRISP-3.     

Effects of the Bowman-Birk inhibitor on growth, invasion, and clonogenic survival of human prostate epithelial cells and prostate cancer cells

BACKGROUND: The Bowman-Birk inhibitor (BBI) is a soybean-derived serine protease inhibitor with demonstrated anticarcinogenic activity in both in vitro and in vivo systems. METHODS: The effects of BBI and BBI Concentrate (BBIC), a soybean concentrate enriched in BBI, on cell growth, invasion, and/or survival were evaluated by the sulforhodamine B assay, a colony formation assay, the trypan blue dye exclusion assay and an in vitro invasion assay. The cells used in these studies were normal human prostate epithelial cells and prostate epithelial cell lines derived from embryonic prostate tissue (267B1) or benign prostatic hyperplasia (BPH) tissue (BRF-55T) and human prostate cancer cells established by Ki-ras oncogene transfection of 267B1 cells (267B1/Ki-ras) or from metastatic lesions of human prostate cancer (LNCaP and PC-3). RESULTS: BBIC had a statistically significant inhibitory effect on the growth and clonogenic survival of BRF-55T, 267B1/Ki-ras, LNCaP, and PC-3 cells. BBI also inhibited the growth of LNCaP cells and the clonogenic survival of BRF-55T and 267B1/Ki-ras cells and decreased the ability of LNCaP cells to invade across reconstituted basement membrane (Matrigel) when PC-3 cell-conditioned medium was utilized as the chemoattractant. BBI or BBIC did not affect the growth of normal prostate epithelial cells. CONCLUSION: BBI and/or BBIC could be a useful agent for treatment of prostate diseases.     

RNA干扰RelB基因对小鼠RM-1前列腺癌细胞株放射敏感性的影响及其机制

目的:探讨RNA干扰RelB基因对鼠RM-1前列腺癌细胞株放射敏感性的影响及其机制。方法:利用靶向RelB基因的慢病毒载体(pLentilox-sh-RelB),脂质体介导转染RM-1细胞后进行放射(2,4,6,和8Gy剂量)处理培养,分别采用RT-PCR、Western印迹法及流式细胞术等方法检测RelB的mRNA和蛋白表达,锰超氧化物歧化酶(Mn-SOD)活力及细胞放射敏感性的变化。结果:转染后放射处理培养,siRelB-RM-1组RelB的mRNA和蛋白表达水平明显低于siVector-RM-1组和nontrans-RM-1组(P<0.05);放射处理培养后siRelB-RM-1组细胞凋亡百分率明显高于siVector-RM-1组和nontrans-RM-1组(P<0.05);培养后siRelB-RM-1组细胞Mn-SOD活力下降,放射增敏比为5.13。结论:RNA干扰RelB基因可增强鼠RM-1前列腺癌细胞株放射后的放射敏感性,其机制可能与RNA干扰RelB基因,抑制细胞增殖,降低Mn-SOD活力和诱导凋亡有关。     

PSP94 expression after androgen deprivation therapy: a comparative study with prostate specific antigen in benign prostate and prostate cancer

PURPOSE: To examine the clinical use of PSP94 (prostate secretory protein of 94 amino acids) as an androgen independent marker, we conducted a comparative study of prostate samples including benign tissue and cancers which did and did not have androgen deprivation. MATERIALS AND METHODS: Among 163 radical prostatectomy cases 75 had androgen deprivation before operation, while surgery was performed in the remainder without prior hormone treatment. Considering the pathological up grading following hormone therapy, contiguous sections from radical prostatectomy samples were stained for PSP94 and prostate specific antigen (PSA) by immunohistochemistry, and equivalent tumor foci were evaluated by assessing the intensity and extent of the staining. RESULTS: In untreated benign prostate tissue PSP94 and PSA staining was positive and identical in all sections in the no pretreatment group. However, PSP94 expression in the androgen deprivation group was significantly higher than PSA in intensity (p = 0.0005) and extent (p = 0.034). In untreated cancer cases PSP94 intensity and extent demonstrated strong inverse association with Gleason grade (p <0.0001). In contrast, PSA expression was high in every grade, resulting in no statistical association with tumor grade. In the androgen deprivation group PSA staining was decreased in every grade compared to the no pretreatment group. On the other hand, PSP94 expression was decreased in grade 3 tumor foci but increased in grades 4 and 5 tumor foci compared with samples of the corresponding grade in the no pretreatment group (p = 0.0034). CONCLUSIONS: PSP94 expression in benign prostate persists under androgen deprivation compared to PSA. PSP94 synthesis in high grade tumor appears to be activated in the absence of androgen stimulation, indicating the possible alternative pathways in the regulation of PSP94.     

Contragestazol （DL111-IT） inhibits proliferation of human androgen-independent prostate cancer cell line PC3 in vitro and in vivo

Aim： To evaluate the antiproliferative activity of contragestazol （DL111-IT） on the human prostate cancer cell line PC3 in vitro and in vivo and to elucidate its potential molecular mechanisms. Methods： The cell killing ability of DL111-IT was measured by the 3-（4,5-dimethylthia-zol,2-yl）-2,5-diphenyltetrazolium bromide （MTT） reagent assay method and the tumor xenograft model. The cell cycle was analyzed by flow cytometry and protein expression, including retinoblastoma （pRb）, cyclin-dependent kinase 4 （CDK4） and cyclin D 1, was detected by Western blotting. Results： DL111-IT exhibited high efficiency on cell growth inhibition of the human androgen-independent prostate cancer cell line PC3. The drug concentration that yielded 50 % cell inhibition （IC50 value） was 9.9 mg/mL. In the PC3 tumor xenograft study, DL111-IT （1.25 mg/kg-20.0 mg/kg） given once a day for 10 days significantly inhibited tumor growth, with the inhibition rate ranging from 21% to 50 %. Flow cytometric analysis indicated that DL111-IT could cause GI arrest in the PC3 cell line, but not apoptosis. DL111-IT enhanced pRb expression and down-regulated CDK4 and cyclin D 1 expression, suggesting that cell cycle regulation might contribute to the anticancer property of DL 111- IT. Conclusion： DL111-1T inhibits the proliferation of human androgen-independent prostate cancer cell line PC3 in vitro and in vivo by a cell cycle regulation pathway.     

Expression of serotonin receptors 2B and 4 in human prostate cancer tissue and effects of their antagonists on prostate cancer cell lines

OBJECTIVES: Overexpression of receptors to neuroendocrine (NE) cell products has been suggested to contribute to development of hormone-refractory prostate cancer (HRPC). In this study, we evaluated the expression of 5-HTR2B and 5-HTR4 in HRPC, and the effects of their antagonist on PC cell line growth. METHODS: Proteins and mRNA expression was determined by immunohistochemistry, western blot and RT-PCR. Growth inhibition of PC cell lines was determined in vitro using ELISA-BrdU proliferation assay and cell cycle was evaluated by flow cytometry. RESULTS: Immunostaining of 5-HTR2B was observed in low-grade and high-grade tumours, PIN and BPH cells, and in vascular endothelial cells, whereas 5-HTR4 was found predominantly in high-grade tumours. This result was confirmed by western blot analysis. At the mRNA level, 5-HTR4 mRNA was expressed in DU145 and LNCaP cells. Antagonists to both receptor subtypes inhibited proliferation of PC cells in a dose-dependent manner. CONCLUSIONS: The present result indicate that 5-HTRs are present at various tumour stages and that antagonists to these receptors can inhibit the proliferative activity of androgen-independent PC cell lines.     

Immunohistochemical detection of cysteine-rich secretory protein 3 in tissue and in serum from men with cancer or benign enlargement of the prostate gland

BACKGROUND: Recently, the gene for cysteine-rich secretory protein 3 (CRISP-3) was reported to be highly upregulated in prostate cancer (PCa) compared to benign prostatic tissue. The current aims were to investigate diagnostic use of tissue expression and immunodetection in serum of CRISP-3 for detection or monitoring of PCa. METHODS: Radical prostatectomy specimens and tissue microarrays from transurethral resections and metastases were analyzed for CRISP-3 and PSA by immunohistochemistry. CRISP-3 in tissue homogenates and in serum was measured by an in-house ELISA and PSA by a commercially available immunoassay. RESULTS: Immunostaining for CRISP-3 in benign prostatic epithelium was generally weak or not detectable. Specific and strong immunostaining was found in a major proportion of cells in high-grade prostatic-intraepithelial-neoplasia (HG-PIN,12/17 patients), in most primary tumors (111/115), and in lymph node (11/15) and bone (12/15) metastases. CRISP-3 immunostaining intensity was regularly strong in areas of Gleason grades 4/5, where PSA-immunoreaction was less intense. Serum levels of CRISP-3 were not different in patients with PCa (n=152) compared to men with BPH (n=81). There was a very weak co-variation between levels of CRISP-3 versus PSA in serum from PCa patients (P<0.05). After orchiectomy, levels of CRISP-3 in serum decreased in median with 11% compared to a 97% median decrease of PSA in serum from 15/20 patients with advanced PCa. CONCLUSIONS: Strong immunostaining for CRISP-3 is common in HG-PIN and preserved in most PCa specimens, which warrant further immunohistochemical studies of CRISP-3 in PCa. Serum levels of CRISP-3 do not primarily reflect PCa.     

Role of insulin-like growth factor binding proteins in 1alpha,25-dihydroxyvitamin D(3)-induced growth inhibition of human prostate cancer cells

BACKGROUND: The mechanisms underlying 1alpha,25-dihydroxyvitamin D(3) (1,25D)-induced growth inhibition of human prostate cancer cells have not been fully elucidated. To determine whether alterations in the insulin-like growth factor (IGF) signaling axis are associated with 1,25D-induced growth inhibition, we examined the ability of 1,25D to regulate expression of IGF binding proteins (IGFBPs) in human prostate cancer cell lines. METHODS: Northern and Western blot analyses were used to detect 1,25D-induced alterations in IGFBP expression. Additional in vitro studies were performed to determine the role of IGFBP-3 in 1,25D-induced growth inhibition. RESULTS: 1,25D decreased mRNA levels of the growth stimulatory IGFBP-2 and induced IGFBP-3 mRNA in LNCaP and C4-2 cells. 1,25D treatment also increased secreted IGFBP-3 protein levels in prostate cancer cell lines sensitive to 1,25D growth inhibition but had little effect on IGFBP-3 expression in 1,25D-resistant DU145 cells. However, recombinant IGFBP-3 had only a minor effect on LNCaP cell growth in the presence of serum. Furthermore, siRNA duplexes that reduced IGFBP-3 expression did not alter 1,25D growth inhibition in either LNCaP or PC-3 cell lines grown in serum-containing media. CONCLUSIONS: Our studies indicate 1,25D-induced up-regulation of IGFBP-3 is not required for the growth inhibitory effects of 1,25D in prostate cancer cells grown in serum-containing media.     

RANKL acts directly on RANK-expressing prostate tumor cells and mediates migration and expression of tumor metastasis genes

BACKGROUND: Metastases to bone are a frequent complication of human prostate cancer and result in the development of osteoblastic lesions that include an underlying osteoclastic component. Previous studies in rodent models of breast and prostate cancer have established that receptor activator of NF-kappaB ligand (RANKL) inhibition decreases bone lesion development and tumor growth in bone. RANK is essential for osteoclast differentiation, activation, and survival via its expression on osteoclasts and their precursors. RANK expression has also been observed in some tumor cell types such as breast and colon, suggesting that RANKL may play a direct role on tumor cells. METHODS: Male CB17 severe combined immunodeficient (SCID) mice were injected with PC3 cells intratibially and treated with either PBS or human osteprotegerin (OPG)-Fc, a RANKL antagonist. The formation of osteolytic lesions was analyzed by X-ray, and local and systemic levels of RANKL and OPG were analyzed. RANK mRNA and protein expression were assessed on multiple prostate cancer cell lines, and events downstream of RANK activation were studied in PC3 cells in vitro. RESULTS: OPG-Fc treatment of PC3 tumor-bearing mice decreased lesion formation and tumor burden. Systemic and local levels of RANKL expression were increased in PC3 tumor bearing mice. PC3 cells responded to RANKL by activating multiple signaling pathways which resulted in significant changes in expression of genes involved in osteolysis and migration. RANK activation via RANKL resulted in increased invasion of PC3 cells through a collagen matrix. CONCLUSION: These data demonstrate that host stromal RANKL is induced systemically and locally as a result of PC3 prostate tumor growth within the skeleton. RANK is expressed on prostate cancer cells and promotes invasion in a RANKL-dependent manner.     

miR-124通过靶向调控PKM2基因的表达抑制前列腺癌PC3细胞的增殖

目的:探讨miR-124抑制前列腺癌PC3细胞增殖活性的机制。方法:利用荧光素酶报告基因验证miR-124能否靶向作用于丙酮酸激酶M2型(PKM2)3'端非编码区(UTR)。将miR-124 mimic转染至PC3细胞后,采用实时荧光定量PCR和Western印迹检测前列腺癌PC3细胞PKM2 mRNA和蛋白的表达水平,MTT法检测miR-124 mimic与PKM2 siRNA对PC3细胞生长活性的影响。结果:与人前列腺上皮细胞RWPE-1比较,PC3细胞中PKM2 mRNA和蛋白水平表达分别上调(5.12±0.35)倍和(4.05±0.20)倍(P0.05)。荧光素酶报告基因结果证实,PKM2是miR-124调控的靶基因,miR-124可特异性地结合于PKM2 mRNA的3'-UTR。转染miR-124 mimic 24 h后,PKM2蛋白水平下调至阴性对照组(0.16±0.04)倍(P0.05),但对PKM2 mRNA表达无显著影响(P0.05)。MTT结果显示,转染miR-124 mimic和PKM2 siRNA都能显著抑制PC3细胞的增殖,但miR-124 mimic对PC3细胞生长活性的抑制能力较PKM2 siRNA强。转染miR-124 mimic和PKM2 siRNA 24 h和48 h后,PC3细胞的增殖率分别为(66.20±5.10)%和(82.10±6.35)%(P0.05)、(49.34±2.37)%和(70.10±5.80)%(P0.05)。结论:miR-124可通过靶向调控PKM2基因的表达而抑制前列腺癌PC3细胞的增殖。     

Paclitaxel enhanced radiation sensitization for the suppression of human prostate cancer tumor growth via a p53 independent pathway

BACKGROUND: This study investigated the influence of p53 status on treatment using combined paclitaxel and irradiation for human prostate cancer (PC) in vitro and in vivo. METHODS: Enhancement of the radiation response by paclitaxel was determined by MTT and clonogenic assays in four sublines of the human PC cell line, LNCaP, stably transfected to express different p53 mutations found in PC patients. Suppression of xenograft growth by combined paclitaxel and radiation was assessed in NOD.SCID mice in vivo. Expression of p53 and downstream functional proteins, p21 and Bax, was assessed by Western blotting. RESULTS: Paclitaxel (8-10 nM) suppressed cell proliferation by 50% by inducing G2M mitotic arrest in LNCaP cell lines transfected to overexpress wild-type or mutant p53. Exposure to 20 nM paclitaxel before radiation therapy enhanced cytotoxicity in clonogenic assays. The dose and duration of paclitaxel exposure were important in inducing both G2M arrest and cell growth suppression and were critical factors in paclitaxel/irradiation combination therapy. Western blotting indicated that combination therapy increased p21 protein expression to varying degrees in all cell lines. In vivo studies indicated that paclitaxel pre-treatment followed by irradiation significantly suppressed tumor growth compared with either treatment alone. CONCLUSIONS: Pre-treatment with paclitaxel enhances radiation efficacy on cell killing and suppression of growth of human PC cell lines in vitro and in vivo via p53 independent pathways. Paclitaxel has potential for use as a radiosensitizer in the treatment of patients with PC with either wild-type or mutant p53 genetic status.     

Hormone-refractory prostate cancer cells express functional follicle-stimulating hormone receptor (FSHR)

PURPOSE: Understanding growth regulation in hormone-refractory prostate cancer may provide avenues for novel treatment interventions. This study was conducted to characterize the expression of the receptor (FSHR) for follicle-stimulating hormone (FSH) in androgen-independent prostate cancer cell lines and in human malignant prostate tissues. MATERIALS AND METHODS: Western blotting, immunohistochemistry (IHC), and flow cytometric analysis were used to study the expression of FSHR. The effect of FSH on cell growth and clonogenicity was studied using proliferation and clonogenic assays. RESULTS: Immunohistochemistry revealed expression of FSH in PC3 and Du145 cells. FSHR was identified in PC3 and Du145 cells, as well as in human adenocarcinoma of the prostate. The specificity of the FSHR detected on prostate cancer tissues or cells by IHC and Western blotting was confirmed by preabsorbing the antibodies with the immunizing antigens. Stimulation of these hormone-refractory cells with FSH triggered a proliferative response in vitro, suggesting that the receptor is biologically active. CONCLUSION: Hormone-refractory prostate cancer cells express FSH and biologically active FSHR. Our results suggest that FSHR and its ligand may play a role in the regulation of the growth of hormone-refractory prostate cancers.