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Shumin Zhang,
Xu Wang,
Shareen Iqbal,
Yanru Wang,
Adeboye O Osunkoya,
Zhengjia Chen,
Zhuo Chen,
Dong M Shin,
Hongwei Yuan,
Yongqiang A Wang, Haiyen E Zhau,
Leland W K Chung,
Chad Ritenour,
Omer Kucuk,
Daqing Wu
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ABSTRACT: Aberrant expression of epidermal growth factor (EGF) receptors has been associated with hormone-refractory and metastatic prostate cancer (PCa). However, the molecular mechanism for EGF signaling in promoting PCa metastasis remains elusive. Using experimental models of PCa metastasis, we demonstrated that EGF could induce robust epithelial-mesenchymal transition (EMT) and increase invasiveness. Interestingly, EGF was found to be capable of promoting protein turnover of epithelial protein lost in neoplasm (EPLIN), a putative suppressor of EMT and tumor metastasis. Mechanistic study revealed that EGF could activate the phosphorylation, ubiquitination and degradation of EPLIN through an extracellular signal-regulated kinases 1/2 (ERK1/2)-dependent signaling cascade. Pharmacological inhibition of the ERK1/2 pathway effectively antagonized EGF-induced EPLIN degradation. Two serine residues, i.e., Serine 362 and Serine 604, were identified as putative ERK1/2 phosphorylation sites in human EPLIN, whose point mutation rendered resistance to EGF-induced protein turnover. This study elucidated a novel molecular mechanism for EGF regulation of EMT and invasiveness in PCa cells, indicating that blockade of EGF signaling could be beneficial in preventing and retarding PCa metastasis at early stages.
Journal of Biological Chemistry 11/2012; · 4.77 Impact Factor
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ABSTRACT: A three-dimensional (3D) integrated rotating-wall vessel cell-culture system was used to evaluate the interaction between
a human prostate cancer cell line, LNCaP, and microcarrier beads alone, or microcarrier beads previously seeded with either
prostate or bone stromal cells. Upon coculture of LNCaP cells with microcarrier beads either in the presence or in the absence
of prostate or bone stromal cells, 3D prostate organoids were formed with the expected hormonal responsiveness to androgen,
increased cell growth, and prostate-specific antigen production. In this communication, we define permanent phenotypic and
genotypic changes of LNCaP cells upon coculture with microcarrier beads alone, or with microcarrier beads previously seeded
with either prostate or bone stromal cells. Most notably, we observed selective genetic changes, i.e., chromosomal losses
or gains, as evaluated by both conventional cytogenetic and comparative genomic hybridization, in LNCaP sublines derived from
the prostate organoids. Moreover, the derivative LNCaP cells appear to have altered growth profiles, and exhibit permanent
and stable changes in response to androgen, estrogen, and growth factors. The derivative LNCaP sublines showed increased anchorage-independent
growth rate, and enhanced tumorigenicity and metastatic potential when inoculated orthotopically in castrated athymic mice.
Our results support the hypothesis that resembles “adaptive mutation” such as has been described in bacteria subjected to
nutritional starvation. The occurrence of such permanent changes may be highly contact dependent, and appears to be driven
by specific microenvironmental factors surrounding the tumor cell epithelium grown as 3D prostate organoids.
In Vitro Cellular & Developmental Biology - Animal 04/2012; 37(3):127-140. · 1.31 Impact Factor
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ABSTRACT: To develop and characterize a novel cell culture method for the generation of undifferentiated and differentiated human mesenchymal stem cell 3D structures, we utilized the RWV system with a gelatin-based scaffold. 3 × 10 6 cells generated homogeneous spheroids and maximum spheroid loading was accomplished after 3 days of culture. Spheroids cultured in undifferentiated spheroids of 3 and 10 days retained expression of CD44, without expression of differentiation markers. Spheroids cultured in adipogenic and osteogenic differentiation media exhibited oil red O staining and von Kossa staining, respectively. Further characterization of osteogenic lineage, showed that 10 day spheroids exhibited stronger calcification than any other experimental group corresponding with significant expression of vitamin D receptor, alkaline phosphatase, and ERp60 . In conclusion this study describes a novel RWV culture method that allowed efficacious engineering of undifferentiated human mesenchymal stem cell spheroids and rapid osteogenic differentiation. The use of gelatin scaffolds holds promise to design implantable stem cell tissue of various sizes and shapes for future regenerative treatment.
Cell Regeneration. 01/2012; Volume 1(1-1:2).
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ABSTRACT: We have previously shown that human prostate cancer cells are capable of acquiring malignant attributes through interaction with stromal cells in the tumor microenvironment, while the interacting stromal cells can also become affected with both phenotypic and genotypic alterations. This study used a co-culture model to investigate the mechanism underlying the co-evolution of cancer and stromal cells. Red fluorescent androgen-dependent LNCaP prostate cancer cells were cultured with a matched pair of normal and cancer-associated prostate myofibroblast cells to simulate cancer-stromal interaction, and cellular changes in the co-culture were documented by tracking the red fluorescence. We found frequent spontaneous fusions between cancer and stromal cells throughout the co-culture. In colony formation assays assessing the fate of the hybrid cells, most of the cancer-stromal fusion hybrids remained growth-arrested and eventually perished. However, some of the hybrids survived to form colonies from the co-culture with cancer-associated stromal cells. These derivative clones showed genomic alterations together with androgen-independent phenotype. The results from this study reveal that prostate cancer cells are fusogenic, and cancer-stromal interaction can lead to spontaneous fusion between the two cell types. While a cancer-stromal fusion strategy may allow the stromal compartment to annihilate invading cancer cells, certain cancer-stromal hybrids with increased survival capability may escape annihilation to form a derivative cancer cell population with an altered genotype and increased malignancy. Cancer-stromal fusion thus lays a foundation for an incessant co-evolution between cancer and the cancer-associated stromal cells in the tumor microenvironment.
PLoS ONE 01/2012; 7(8):e42653. · 4.09 Impact Factor
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Shareen Iqbal,
Shumin Zhang,
Adel Driss,
Zhi-Ren Liu,
Hyeong-Reh Choi Kim,
Yanru Wang,
Chad Ritenour, Haiyen E Zhau,
Omer Kucuk,
Leland W K Chung,
Daqing Wu
[show abstract]
[hide abstract]
ABSTRACT: Aberrant platelet derived growth factor (PDGF) signaling has been associated with prostate cancer (PCa) progression. However, its role in the regulation of PCa cell growth and survival has not been well characterized.
Using experimental models that closely mimic clinical pathophysiology of PCa progression, we demonstrated that PDGF is a survival factor in PCa cells through upregulation of myeloid cell leukemia-1 (Mcl-1). PDGF treatment induced rapid nuclear translocation of β-catenin, presumably mediated by c-Abl and p68 signaling. Intriguingly, PDGF promoted formation of a nuclear transcriptional complex consisting of β-catenin and hypoxia-inducible factor (HIF)-1α, and its binding to Mcl-1 promoter. Deletion of a putative hypoxia response element (HRE) within the Mcl-1 promoter attenuated PDGF effects on Mcl-1 expression. Blockade of PDGF receptor (PDGFR) signaling with a pharmacological inhibitor AG-17 abrogated PDGF induction of Mcl-1, and induced apoptosis in metastatic PCa cells.
Our study elucidated a crucial survival mechanism in PCa cells, indicating that interruption of the PDGF-Mcl-1 survival signal may provide a novel strategy for treating PCa metastasis.
PLoS ONE 01/2012; 7(1):e30764. · 4.09 Impact Factor
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ABSTRACT: We previously cloned prosaposin (PSAP) from metastatic castrate-resistant prostate cancer (mCRPCa) cells and demonstrated its genomic amplification and/or overexpression in metastatic PCa cell lines, xenografts, and lymph node metastases. The clinicohistopathological significance of serum PSAP levels and its tissue expression and association with predictive or prognostic variable in primary or advanced PCa are not known.
We examined PSAP expression by immunohistochemical staining during early embryogenic development of the prostate and within a large tissue microarray which included 266 benign and malignant prostate tissues. In addition, serum PSAP levels in the age-adjusted normal male population and in 154 normal individuals and patients with primary or mCRPCa were measured by an ELISA assay.
Univariate and multivariate analyses revealed a significant and inverse association between PSAP expression and clinical stages II and III tumors, dominant Gleason patterns 3 and 4, and seminal vesicle invasion. In the normal male population, the lowest serum PSAP level was detected before puberty, peaked at the most reproductive age group (20- to 39-year old), and then, decreased to a range between the two groups for men above 40-year old. Regardless of age and when compared with normal individuals, serum PSAP levels significantly decreased in primary organ-confined PCa, but increased in those with mCRPCa.
Our results show that PSAP has the potential to differentiate between primary and advanced PCa. Additional large-scale studies are needed to define the usefulness of tissue expression or serum PSAP levels as a diagnostic or prognostic marker or as a therapeutic target in PCa.
The Prostate 05/2011; 72(3):253-69. · 3.48 Impact Factor
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ABSTRACT: Sonic hedgehog (Shh) signaling plays a pivotal role in stromal-epithelial interaction during normal development but its role in tumor-stromal interaction during carcinogenic progression is less well defined. Since hormone refractory prostate cancer with bone metastasis is difficult to treat, it is crucial to investigate how androgen independent (AI) human prostate cancer cells communicate with their associated stroma.
Shh and its target transcription factor, Gli1 mRNA, were assessed by RT-PCR and/or quantitative RT-PCR in co-cultured cell recombinants comprised of AI C4-2 either with NPF (prostate fibroblasts from normal/benign prostate gland) or CPF (cancer-associated stromal fibroblasts) under Shh/cyclopamine (a hedgehog signaling inhibitor) treatment. Human bone marrow stromal (HS27A) cells were used as controls. In vivo investigation was performed by checking serum PSA and immunohistochemical staining for the apoptosis-associated M30 gene in mice bearing chimeric C4-2/NPF tumors.
We found that (1) Shh has minimal growth-stimulating effects on prostate cancer cells, but it stimulated the growth of NPF but not CPF; (2) active Shh signaling was found between AI C4-2 cells and NPF but not CPF; and (3) osteonectin (ON) is a Gli1 target gene in NPF and not in CPF, and ON up-regulation in NPF can be blocked by cyclopamine
Based on co-culture and chimeric tumor models, active Shh-mediated signaling was demonstrated between AI prostate cancer and NPF in a paracrine- and tumor progression-dependent manner. Our study suggests that drugs like cyclopamine that interfere with Shh signaling could be beneficial in preventing AI progression in prostate cancer cells.
The Prostate 04/2011; 71(16):1711-22. · 3.48 Impact Factor
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Bahig M Shehata,
James M Elmore,
Yasmin Bootwala,
Charlotte K Steelman,
Jessica B Bare,
Carla J Shoffeitt,
Ruoxiang Wang, Haiyen E Zhau,
Dalin He,
Guodong Zhu,
Leland W Chung
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ABSTRACT: Hypospadias is a common congenital anomalies, yet its molecular basis remains unknown. Recent studies have linked perturbations in the Hedgehog signaling pathway to hypospadias. However, the expression of Sonic hedgehog (Shh) has not been reported during genital development. Immunohistochemical staining for Shh and its receptors was applied to 10 human fetal penises ranging from 12 to 29 weeks gestation. The intensity of Shh staining was greatest in the urethral epithelium at 14 weeks gestation, correlating with the time of urethral tubularization. Results suggest a role for Shh in human male genital development.
Fetal and pediatric pathology 03/2011; 30(4):244-51. · 0.36 Impact Factor
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ABSTRACT: Bone metastasis is one of the predominant causes of cancer lethality. This study demonstrates for the first time how β2-microglobulin (β2-M) supports lethal metastasis in vivo in human prostate, breast, lung, and renal cancer cells. β2-M mediates this process by activating epithelial to mesenchymal transition (EMT) to promote lethal bone and soft tissue metastases in host mice. β2-M interacts with its receptor, hemochromatosis (HFE) protein, to modulate iron responsive pathways in cancer cells. Inhibition of either β2-M or HFE results in reversion of EMT. These results demonstrate the role of β2-M in cancer metastasis and lethality. Thus, β2-M and its downstream signaling pathways are promising prognostic markers of cancer metastases and novel therapeutic targets for cancer therapy.
Cancer Research 03/2011; 71(7):2600-10. · 7.86 Impact Factor
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Dong Zhang,
Dalin He,
Yan Xue,
Ruoxiang Wang,
Kaijie Wu,
Hongjun Xie,
Jin Zeng,
Xinyang Wang, Haiyen E Zhau,
Leland W K Chung,
Luke S Chang,
Lei Li
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ABSTRACT: PrLZ/PC-1 is a newly identified, prostate-specific and androgen-inducible gene. Our previous study showed that PrLZ can enhance the proliferation and invasive capability of LNCaP cells, contributing to the development of prostate cancer. However, its potential role in androgen-independent processes remains elusive. In this study, we showed that PrLZ enhanced in vitro growth and colony formation of prostate cancer cells on androgen deprivation as well as tumorigenicity in castrated nude mice. In addition, PrLZ stabilized mitochondrial transmembrane potential, prevented release of cytochrome c from mitochondria to cytoplasm, and inhibited intrinsic apoptosis induced by androgen depletion. Mechanistically, PrLZ elevated the phosphorylation of Akt and Stat3 and upregulated Bcl-2 expression. Our data indicate that PrLZ protects prostate cancer cells from apoptosis and promotes tumor progression following androgen deprivation. In summary, we propose that PrLZ is a novel antiapoptotic gene that is specifically activated in prostate cancer cells escaping androgen deprivation may offer an appealing therapeutic target to prevent or treat advanced prostate malignancy.
Cancer Research 03/2011; 71(6):2193-202. · 7.86 Impact Factor
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ABSTRACT: Prostate tumor cells frequently show the features of osteoblasts, which are differentiated from bone marrow mesenchymal stem cells. We examined human prostate cancer cell lines and clinical prostate cancer specimens for additional bone marrow mesenchymal stem cell properties.
Prostate cancer cell lines were induced for osteoblastogenic and adipogenic differentiation, detected by standard staining methods and confirmed by lineage-specific marker expression. Abnormal expression of the markers was then assessed in clinical prostate cancer specimens.
After osteoblastogenic induction, cells of the LNCaP lineage, PC-3 lineage, and DU145 displayed osteoblastic features. Upon adipogenic induction, PC-3 lineage and DU145 cells differentiated into adipocyte-like cells. The adipocyte-like cancer cells expressed brown adipocyte-specific markers, suggesting differentiation along the brown adipocyte lineage. The adipogenic differentiation was accompanied by growth inhibition, and most of the adipocyte-like cancer cells were committed to apoptotic death. During cyclic treatments with adipogenic differentiation medium and then with control medium, the cancer cells could commit to repeated adipogenic differentiation and retrodifferentiation. In clinical prostate cancer specimens, the expression of uncoupling protein 1 (UCP1), a brown fat-specific marker, was enhanced with the level of expression correlated to disease progression from primary to bone metastatic cancers.
This study thus revealed that prostate cancer cells harbor the stem cell properties of bone marrow mesenchymal stem cells. The abnormally expressed adipogenic UCP1 protein may serve as a unique marker, while adipogenic induction can be explored as a differentiation therapy for prostate cancer progression and bone metastasis.
Clinical Cancer Research 02/2011; 17(8):2159-69. · 7.74 Impact Factor
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Hui-Wen Lue,
Xiaojian Yang,
Ruoxiang Wang,
Weiping Qian,
Roy Z H Xu,
Robert Lyles,
Adeboye O Osunkoya,
Binhua P Zhou,
Robert L Vessella,
Majd Zayzafoon,
Zhi-Ren Liu, Haiyen E Zhau,
Leland W K Chung
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ABSTRACT: LIV-1, a zinc transporter, is an effector molecule downstream from soluble growth factors. This protein has been shown to promote epithelial-to-mesenchymal transition (EMT) in human pancreatic, breast, and prostate cancer cells. Despite the implication of LIV-1 in cancer growth and metastasis, there has been no study to determine the role of LIV-1 in prostate cancer progression. Moreover, there was no clear delineation of the molecular mechanism underlying LIV-1 function in cancer cells. In the present communication, we found increased LIV-1 expression in benign, PIN, primary and bone metastatic human prostate cancer. We characterized the mechanism by which LIV-1 drives human prostate cancer EMT in an androgen-refractory prostate cancer cells (ARCaP) prostate cancer bone metastasis model. LIV-1, when overexpressed in ARCaP(E) (derivative cells of ARCaP with epithelial phenotype) cells, promoted EMT irreversibly. LIV-1 overexpressed ARCaP(E) cells had elevated levels of HB-EGF and matrix metalloproteinase (MMP) 2 and MMP 9 proteolytic enzyme activities, without affecting intracellular zinc concentration. The activation of MMPs resulted in the shedding of heparin binding-epidermal growth factor (HB-EGF) from ARCaP(E) cells that elicited constitutive epidermal growth factor receptor (EGFR) phosphorylation and its downstream extracellular signal regulated kinase (ERK) signaling. These results suggest that LIV-1 is involved in prostate cancer progression as an intracellular target of growth factor receptor signaling which promoted EMT and cancer metastasis. LIV-1 could be an attractive therapeutic target for the eradication of pre-existing human prostate cancer and bone and soft tissue metastases.
PLoS ONE 01/2011; 6(11):e27720. · 4.09 Impact Factor
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Peizhen Hu,
Gina C-Y Chu,
Guodong Zhu,
Hua Yang,
Daniel Luthringer,
Gail Prins,
Fouad Habib,
Yuzhuo Wang,
Ruoxiang Wang,
Leland W K Chung, Haiyen E Zhau
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ABSTRACT: The potential application of multiplexed quantum dot labeling (MQDL) for cancer detection and prognosis and monitoring therapeutic responses has attracted the interests of bioengineers, pathologists and cancer biologists. Many published studies claim that MQDL is effective for cancer biomarker detection and useful in cancer diagnosis and prognosis, these studies have not been standardized against quantitative biochemical and molecular determinations. In the present study, we used a molecularly characterized human prostate cancer cell model exhibiting activated c-Met signaling with epithelial to mesenchymal transition (EMT) and lethal metastatic progression to bone and soft tissues as the gold standard, and compared the c-Met cell signaling network in this model, in clinical human prostate cancer tissue specimens and in a castration-resistant human prostate cancer xenograft model. We observed c-Met signaling network activation, manifested by increased phosphorylated c-Met in all three. The downstream survival signaling network was mediated by NF-κB and Mcl-1 and EMT was driven by receptor activator of NF-κB ligand (RANKL), at the single cell level in clinical prostate cancer specimens and the xenograft model. Results were confirmed by real-time RT-PCR and western blots in a human prostate cancer cell model. MQDL is a powerful tool for assessing biomarker expression and it offers molecular insights into cancer progression at both the cell and tissue level with high degree of sensitivity.
PLoS ONE 01/2011; 6(12):e28670. · 4.09 Impact Factor
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ABSTRACT: BACKGROUND
The α2 chain of the interleukin-13 receptor (IL13Rα2) is a high-affinity receptor and a candidate target for cytotoxic killing of cancer cells. Availability of a human prostate cancer cell line with high level of IL13Rα2 expression will facilitate the development of therapeutic modalities.METHODSARCaPE and ARCaPM human prostate cancer cell lines were subjected to comparative analyses of gene expression. Expression of the IL13Rα2 protein was confirmed by Western blotting and immunostaining. IL13Rα2 proteins in xenograft tumors and clinical human prostate cancer specimens were detected by specific antibodies. LNCaP prostate cancer cells stably transfected with IL13Rα2 were examined for accelerated growth in athymic mice.RESULTSWe found that IL13Rα2 proteins could be detected in both the ARCaPE and ARCaPM cells, but the expression level in ARCaPM was more than 17-fold higher than in ARCaPE cells. Importantly, the ARCaP lineage represented the only human prostate cancer cell line that expresses IL13Rα2 proteins at the level detectable by Western blotting. Expression of IL13Rα2 was accompanied by resistance to the anti-tumor activity of interleukin-13 (IL-13). ARCaP cells were found to be insensitive to growth inhibition upon IL-13 treatment, while overexpression of IL13Rα2 in LNCaP cells promoted intratibial tumor growth in athymic mice.CONCLUSIONS
Differential IL13Rα2 expression may account for the high tumorigenic and metastatic potential of ARCaPM cells. The unique expression of IL13Rα2 makes ARCaP lineage an attractive model for evaluating the targeting efficacy of therapeutic agents based on IL13Rα2 protein expression. Prostate © 2010 Wiley-Liss, Inc.
The Prostate 06/2010; 70(9):993 - 1001. · 3.48 Impact Factor
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Xiaojian Yang,
Chunmeng Shi,
Rong Tong,
Weiping Qian, Haiyen E Zhau,
Ruoxiang Wang,
Guodong Zhu,
Jianjun Cheng,
Vincent W Yang,
Tianmin Cheng,
Maged Henary,
Lucjan Strekowski,
Leland W K Chung
[show abstract]
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ABSTRACT: Near-IR fluorescence imaging has great potential for noninvasive in vivo imaging of tumors. In this study, we show the preferential uptake and retention of two hepatamethine cyanine dyes, IR-783 and MHI-148, in tumor cells and tissues.
IR-783 and MHI-148 were investigated for their ability to accumulate in human cancer cells, tumor xenografts, and spontaneous mouse tumors in transgenic animals. Time- and concentration-dependent dye uptake and retention in normal and cancer cells and tissues were compared, and subcellular localization of the dyes and mechanisms of the dye uptake and retention in tumor cells were evaluated using organelle-specific tracking dyes and bromosulfophthalein, a competitive inhibitor of organic anion transporting peptides. These dyes were used to detect human cancer metastases in a mouse model and differentiate cancer cells from normal cells in blood.
These near-IR hepatamethine cyanine dyes were retained in cancer cells but not normal cells, in tumor xenografts, and in spontaneous tumors in transgenic mice. They can be used to detect cancer metastasis and cancer cells in blood with a high degree of sensitivity. The dyes were found to concentrate in the mitochondria and lysosomes of cancer cells, probably through organic anion transporting peptides, because the dye uptake and retention in cancer cells can be blocked completely by bromosulfophthalein. These dyes, when injected to mice, did not cause systemic toxicity.
These two heptamethine cyanine dyes are promising imaging agents for human cancers and can be further exploited to improve cancer detection, prognosis, and treatment.
Clinical Cancer Research 05/2010; 16(10):2833-44. · 7.74 Impact Factor
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ABSTRACT: Prostate stromal cells may play binary roles in the process of prostate cancer development. As the first to be encountered by infiltrating prostate cancer cells, prostate stromal cells form the first defense line against prostate cancer progression and metastasis. However, interaction between prostate cancer and stromal cells may facilitate the formation of a tumor microenvironment favoring cancer cell growth and survival. To establish an experimental system for studying the interaction between cancer and stromal cells, we isolated three matched pairs of normal and cancer-associated human prostate stromal clones. In this report, we describe the morphologic and behavioral characteristics of these cells and their effect on LNCaP prostate cancer cells in co-culture. Unlike LNCaP prostate cancer cells, the isolated prostate stromal clones are large fibroblast-like cells with a slow proliferation rate. Growth and survival of these clones are not affected by androgens. The stromal cells display high resistance to serum starvation, while cancer-associated stromal clones have differentiated survival ability. In co-culture experiments, the stromal cells protected some LNCaP prostate cancer cells from death by serum starvation, and cancer-associated stromal clones showed more protection. This work thus established a panel of valuable human prostate stromal cell lines, which could be used in co-culture to study the interaction between prostate cancer and prostate stromal cells.
In Vitro Cellular & Developmental Biology - Animal 04/2010; 46(6):538-46. · 1.31 Impact Factor
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ABSTRACT: A new cis-acting element, sterol regulatory element-binding protein-1 (SREBP-1) binding site, within the 5'-flanking human androgen receptor (AR) promoter region and its binding transcription factor, SREBP-1, was identified to regulate AR transcription in AR-positive human prostate cancer cells. We further characterized the molecular mechanism by which a novel anti-beta2-microglobulin monoclonal antibody (beta2M mAb), shown to induce massive cell death in a number of human and mouse cancer cell lines, interrupted multiple cell signaling pathways in human prostate cancer cells. beta2M mAb decreased AR expression through inactivation of MAPK and SREBP-1. By inactivation of MAPK, beta2M mAb decreased prostate cancer cell proliferation and survival. By inhibition of SREBP-1, beta2M mAb reduced fatty acid and lipid levels, an integral component of cell membrane, cell signaling mediators, and energy metabolism. These results provide for the first time a molecular link between the beta2M intracellular signaling axis mediated by MAPK and SREBP-1 and involving lipid signaling, which collectively regulates AR expression and function. Antagonizing beta2M by beta2M mAb may be an effective therapeutic approach simultaneously targeting multiple downstream signaling pathways converging with MAPK, SREBP-1, and AR, important for controlling prostate cancer cell growth, survival, and progression.
Journal of Biological Chemistry 03/2010; 285(11):7947-56. · 4.77 Impact Factor
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[show abstract]
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ABSTRACT: We have reported that human prostate cancer ARCaP(E) cells undertake epithelial to mesenchymal transition (EMT) when stimulated by certain soluble factors, and that EMT is regulated by surface receptor-elicited signaling pathways through protein phosphorylation. It is known that phorbol ester phorbol-12-myristate-13-acetate (PMA), a potent antagonist to both conventional and novel protein kinase C (PKC) isoenzymes, induces cancer cell scattering.
To assess the effect of PMA on EMT, ARCaP(E) cells were treated with PMA and were assayed for EMT-related morphologic and behavioral changes. Specific inhibitors were used to investigate the PMA-induced EMT.
PMA at 100 nM induced EMT in a time-dependent manner, resulting in a complete change from epithelial to mesenchymal stromal morphology. Concurrently, PMA inhibited expression of epithelial marker E-cadherin and increased the level of stromal marker protein vimentin, while the treated cells showed increased migratory and invasive capacities. Using specific inhibitors, we confirmed that the effect of PMA was mediated by PKC, while isoenzymes of the novel PKC subfamily were implicated as the main mediator. Finally, we determined that the EMT was dependent on newly synthesized proteins, because inhibitors for gene transcription and protein translation could both inhibit the initiation of EMT.
Although PMA is well known for its effects on cell migration and tumor formation, this work is the first to define PMA as an EMT inducer in prostate cancer cells. Further investigation in this experimental model may reveal important regulatory mechanisms and additional molecular changes underlying EMT.
The Prostate 03/2010; 70(10):1119-26. · 3.48 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The alpha2 chain of the interleukin-13 receptor (IL13Ralpha2) is a high-affinity receptor and a candidate target for cytotoxic killing of cancer cells. Availability of a human prostate cancer cell line with high level of IL13Ralpha2 expression will facilitate the development of therapeutic modalities.
ARCaP(E) and ARCaP(M) human prostate cancer cell lines were subjected to comparative analyses of gene expression. Expression of the IL13Ralpha2 protein was confirmed by Western blotting and immunostaining. IL13Ralpha2 proteins in xenograft tumors and clinical human prostate cancer specimens were detected by specific antibodies. LNCaP prostate cancer cells stably transfected with IL13Ralpha2 were examined for accelerated growth in athymic mice.
We found that IL13Ralpha2 proteins could be detected in both the ARCaP(E) and ARCaP(M) cells, but the expression level in ARCaP(M) was more than 17-fold higher than in ARCaP(E) cells. Importantly, the ARCaP lineage represented the only human prostate cancer cell line that expresses IL13Ralpha2 proteins at the level detectable by Western blotting. Expression of IL13Ralpha2 was accompanied by resistance to the anti-tumor activity of interleukin-13 (IL-13). ARCaP cells were found to be insensitive to growth inhibition upon IL-13 treatment, while overexpression of IL13Ralpha2 in LNCaP cells promoted intratibial tumor growth in athymic mice.
Differential IL13Ralpha2 expression may account for the high tumorigenic and metastatic potential of ARCaP(M) cells. The unique expression of IL13Ralpha2 makes ARCaP lineage an attractive model for evaluating the targeting efficacy of therapeutic agents based on IL13Ralpha2 protein expression.
The Prostate 02/2010; 70(9):993-1001. · 3.48 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: A new cis-acting element, sterol regulatory element-binding protein-1 (SREBP-1) binding site, within the 5′-flanking human
androgen receptor (AR) promoter region and its binding transcription factor, SREBP-1, was identified to regulate AR transcription
in AR-positive human prostate cancer cells. We further characterized the molecular mechanism by which a novel anti-β2-microglobulin
monoclonal antibody (β2M mAb), shown to induce massive cell death in a number of human and mouse cancer cell lines, interrupted
multiple cell signaling pathways in human prostate cancer cells. β2M mAb decreased AR expression through inactivation of mitogen-activated
protein kinase (MAPK) and SREBP-1. By inactivation of MAPK, β2M mAb decreased prostate cancer cell proliferation and survival.
By inhibition of SREBP-1, β2M mAb reduced fatty acid and lipid levels, an integral component of cell membrane, cell signaling
mediators and energy metabolism. These results provide for the first time a molecular link between the β2M intracellular signaling
axis mediated by MAPK and SREBP-1 and involving lipid signaling, which collectively regulates AR expression and function.
Antagonizing β2M by β2M mAb may be an effective therapeutic approach simultaneously targeting multiple downstream signaling
pathways converging with MAPK, SREBP-1 and AR, important for controlling prostate cancer cell growth, survival and progression.
Journal of Biological Chemistry 01/2010; · 4.77 Impact Factor
