ObjectiveTo explore the expression of pituitary tumor transforming gene 1 (PTTG1) during the transformation of prostate cancer from androgen-dependent (ADPC) to androgen-independent (AIPC).

METHODSWe established an AIPC cell model LNCaP-AI by culturing the androgen-dependent LNCaP cell line in the hormone-deprived medium for over 3 months. The cell model was verified and the PTTG1 expression in the LNCaP cells was detected by Western blot and RT-PCR during hormone deprivation.

RESULTSThe AIPC cell model LNCaP-AI was successfully established. The PTTG1 expression was gradually increased in the LNCaP cells with the prolonged time of hormone deprivation and the expressions of matrix metalloproteinases MMP-2 and -9 were elevated at the same time.

CONCLUSIONSThe expression of PTTG1 is increased gradually in AIPC, which may be a target of gene therapy for advanced prostate cancer.

Blotting, Western ; Cell Line, Tumor ; Gene Expression Regulation, Neoplastic ; Humans ; Male ; Matrix Metalloproteinase 2 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Neoplasms, Hormone-Dependent ; Prostatic Neoplasms ; enzymology ; genetics ; Securin ; genetics

BACKGROUNDProstate specific membrane antigen (PSMA) can facilitate the growth, migration, and invasion of the LNCaP prostate cancer cell lines, but the underlying molecular mechanisms have not yet been clearly defined. Here, we investigated whether PSMA serves as a novel regulator of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling by employing PSMA knockdown model and PI3K pharmacological inhibitor (LY294002) in LNCaP prostate cancer cells.

METHODSPSMA knockdown had been stably established by transfecting with lentivirus-mediated siRNA in our previous study. Then, LNCaP cells were divided into interference, non-interference, and blank groups. We first testified the efficacy of PSMA knockdown in our LNCaP cell line. Then, we compared the expression of PSMA and total/activated Akt by Western blotting in the above three groups with or without LY294002 treatment. Furthermore, immunocytochemistry was performed to confirm the changes of activated Akt (p-Akt, Ser473) in groups. Besides, cell proliferation, migration, and cell cycle were measured by CCK-8 assay, Transwell analysis, and Flow cytometry respectively.

RESULTSAfter PSMA knockdown, the level of p-Akt (Ser473) but not of total-Akt (Akt1/2) was significantly decreased when compared with the non-interference and blank groups. However, LY294002 administration significantly reduced the expression of p-Akt (Ser473) in all the three groups. The results of immunocytochemistry further confirmed that PSMA knockdown or LY294002 treatment was associated with p-Akt (Ser473) down-regulation. Decrease of cell proliferation, migration, and survival were also observed upon PSMA knockdown and LY294002 treatment.

CONCLUSIONSTaken together, our results reveal that PI3K/Akt signaling pathway inhibition may serve as a novel molecular mechanism in LNCaP prostate cancer cells of PSMA knockdown and suggest that Akt (Ser473) may play a critical role as a downstream signaling target effector of PSMA in this cellular model.

Antigens, Surface ; genetics ; metabolism ; Cell Line, Tumor ; Glutamate Carboxypeptidase II ; genetics ; metabolism ; Humans ; Male ; Phosphatidylinositol 3-Kinases ; metabolism ; Prostatic Neoplasms ; enzymology ; genetics ; therapy ; Proto-Oncogene Proteins c-akt ; metabolism ; RNA Interference ; Signal Transduction ; genetics ; physiology

Polo-like kinase 1 (Plk1), a well-characterized member of serine/threonine kinases Plk family, has been shown to play pivotal roles in mitosis and cytokinesis in eukaryotic cells. Recent studies suggest that Plk1 not only controls the process of mitosis and cytokinesis, but also, going beyond those previously described functions, plays critical roles in DNA replication and Pten null prostate cancer initiation. In this review, we briefly summarize the functions of Plk1 in mitosis and cytokinesis, and then mainly focus on newly discovered functions of Plk1 in DNA replication and in Pten-null prostate cancer initiation. Furthermore, we briefly introduce the architectures of human and mouse prostate glands and the possible roles of Plk1 in human prostate cancer development. And finally, the newly chemotherapeutic development of small-molecule Plk1 inhibitors to target Plk1 in cancer treatment and their translational studies are also briefly reviewed.
Animals ; Cell Cycle Checkpoints ; Cell Cycle Proteins ; antagonists & inhibitors ; metabolism ; physiology ; Cytokinesis ; DNA Replication ; Humans ; Male ; Mitosis ; Models, Biological ; PTEN Phosphohydrolase ; genetics ; metabolism ; Prostatic Neoplasms ; drug therapy ; enzymology ; pathology ; Protein Kinase Inhibitors ; therapeutic use ; Protein-Serine-Threonine Kinases ; antagonists & inhibitors ; metabolism ; physiology ; Proto-Oncogene Proteins ; antagonists & inhibitors ; metabolism ; physiology ; Substrate Specificity

Glucosamine, a naturally occurring amino monosaccharide, has been reported to play a role in the regulation of apoptosis more than half century. However the effect of glucosamine on tumor cells and the involved molecular mechanisms have not been thoroughly investigated. Glucosamine enters the hexosamine biosynthetic pathway (HBP) downstream of the rate-limiting step catalyzed by the GFAT (glutamine:fluctose-6-phosphate amidotransferase), providing UDP-GlcNAc substrates for O-linked beta-N-acetylglucosamine (O-GlcNAc) protein modification. Considering that O-GlcNAc modification of proteasome subunits inhibits its activity, we examined whether glucosamine induces growth inhibition via affecting proteasomal activity. In the present study, we found glucosamine inhibited proteasomal activity and the proliferation of ALVA41 prostate cancer cells. The inhibition of proteasomal activity results in the accumulation of ubiquitinated proteins, followed by induction of apoptosis. In addition, we demonstrated that glucosamine downregulated proteasome activator PA28gamma and overexpression of PA28gamma rescued the proteasomal activity and growth inhibition mediated by glucosamine. We further demonstrated that inhibition of O-GlcNAc abrogated PA28gamma suppression induced by glucosamine. These findings suggest that glucosamine may inhibit growth of ALVA41 cancer cells through downregulation of PA28gamma and inhibition of proteasomal activity via O-GlcNAc modification.
Acetylglucosamine/chemistry/metabolism ; Alloxan/pharmacology ; Apoptosis/*drug effects ; Autoantigens/genetics/*metabolism ; Cell Line, Tumor ; Cell Proliferation/*drug effects ; Gene Expression Regulation, Neoplastic ; Glucosamine/*pharmacology ; Humans ; Male ; Phosphorylation ; Prostatic Neoplasms/*enzymology ; Proteasome Endopeptidase Complex/*antagonists & inhibitors/genetics/metabolism ; RNA, Small Interfering/genetics ; Ubiquitinated Proteins/metabolism

Metastasis represents by far the most feared complication of prostate carcinoma and is the main cause of death for patients. The skeleton is frequently targeted by disseminated cancer cells and represents the sole site of spread in more than 80% of prostate cancer cases. Compatibility between select malignant phenotypes and the microenvironment of colonized tissues is broadly recognized as the culprit for the organ-tropism of cancer cells. Here, we review our recent studies showing that the expression of platelet-derived growth factor receptor alpha (PDGFRα) supports the survival and growth of prostate cancer cells in the skeleton and that the soluble fraction of bone marrow activates PDGFRα in a ligand-independent fashion. Finally, we offer pre-clinical evidence that this receptor is a viable target for therapy.
Animals ; Antibodies, Monoclonal ; therapeutic use ; Bone Marrow ; enzymology ; pathology ; Bone Neoplasms ; prevention & control ; secondary ; Enzyme Activation ; Humans ; Male ; Prostatic Neoplasms ; drug therapy ; enzymology ; pathology ; Receptor, Platelet-Derived Growth Factor alpha ; antagonists & inhibitors ; genetics ; immunology ; metabolism ; Signal Transduction ; Transcriptional Activation

OBJECTIVETo investigate the enhancing effect of all-trans retinoic acid (ATRA) on the bystander effect of the herpes simplex virus thymidine kinase(HSV-TK)/ganciclovir (GCV) against androgen unresponsive prostate cancer.

METHODSThe bystander effect of the HSV-TK/GCV system was measured by methyl thiazolyl tetrazolium (MTT) assay on PC-3 cells before and after ATRA treatment. The growth and the histopathology of transplant tumors were observed in 4 groups of nude mice with prostate cancer.

RESULTSATRA augmented significantly the bystander effect of the HSV-TK/GCV system by reducing TK positive PC-3 cells from 50% to 30% (P < 0.05). HSV-TK showed an inhibiting effect, while ATRA with the HSV-TK/GCV system produced significant effect on prostate cancer 1 week earlier than the former (P < 0.05).

CONCLUSIONATRA can argument the in vivo and in vitro bystander effect of the HSV-TK/GCV system in the treatment of androgen unresponsive prostate cancer.

Animals ; Antineoplastic Agents ; pharmacology ; Bystander Effect ; drug effects ; Cell Line, Tumor ; Cell Survival ; drug effects ; Ganciclovir ; pharmacology ; Genes, Transgenic, Suicide ; genetics ; Genetic Therapy ; methods ; Humans ; Male ; Mice ; Mice, Nude ; Prostatic Neoplasms ; genetics ; pathology ; therapy ; Reverse Transcriptase Polymerase Chain Reaction ; Simplexvirus ; enzymology ; Thymidine Kinase ; genetics ; metabolism ; Tretinoin ; pharmacology ; Xenograft Model Antitumor Assays ; methods

OBJECTIVETo investigate the inhibiting effect of telomerase with hTERT antisense on TNF-alpha-induced apoptosis in prostate cancer cells PC3.

METHODSAntisense phosphorothioate oligodeoxynucleotide (AS PS-ODN) was synthesized and purified. Telomerase activity was measured by telomeric repeat amplification protocol (TRAP) and telomerase PCR-ELISA Kit, cell viability was determined by MTT assay, and cell apoptosis was observed by morphological method and determined by flow cytometry.

RESULTSAS PS-ODN could significantly inhibit the telomerase activity and increase the susceptibility of TNF-alpha-induced apoptosis of PC3 cells.

CONCLUSIONInhibition of telomerase with hTERT antisense can enhance TNF-alpha-induced apoptosis in prostate cancer cells.

Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Survival ; drug effects ; Enzyme-Linked Immunosorbent Assay ; Humans ; Male ; Oligodeoxyribonucleotides, Antisense ; genetics ; pharmacology ; Polymerase Chain Reaction ; Prostatic Neoplasms ; enzymology ; genetics ; pathology ; Telomerase ; antagonists & inhibitors ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; pharmacology

AIMTo characterize the matrix metalloproteinases (MMP)-2 promoter and to identify androgen response elements (AREs) involved in androgen-induced MMP-2 expression.

METHODSMMP-2 mRNA levels was determined by reverse transcription-polymerase chain reaction (RT-PCR). MMP-2 promoter-driven luciferase assays were used to determine the fragments responsible for androgen-induced activity. Chromatin-immunoprecipitation assay and electrophoretic mobility shift assays (EMSA) were used to verify the identified AREs in the MMP-2 promoter.

RESULTSAndrogen significantly induced MMP-2 expression at the mRNA level, which was blocked by the androgen antagonist bicalutamide. Deletion of a region encompassing base pairs -1591 to -1259 (relative to the start codon) of the MMP-2 promoter led to a significant loss of androgen-induced reporter activity. Additional deletion of the 5'-region up to -562 bp further reduced the androgen-induced MMP-2 promoter activity. Sequence analysis of these two regions revealed two putative ARE motifs. Introducing mutations in the putative ARE motifs by site-directed mutagenesis approach resulted in a dramatic loss of androgen-induced MMP-2 promoter activity, indicating that the putative ARE motifs are required for androgen-stimulated MMP-2 expression. Most importantly, the androgen receptor (AR) interacted with both motif-containing promoter regions in vivo in a chromatin immunoprecipitation assay after androgen treatment. Furthermore, the AR specifically bound to the wild-type but not mutated ARE motifs-containing probes in an in vitro EMSA assay.

CONCLUSIONTwo ARE motifs were identified to be responsible for androgen-induced MMP-2 expression in prostate cancer cells.

Androgens ; pharmacology ; Cell Line, Tumor ; Chromatin ; genetics ; DNA Primers ; Gene Expression Regulation, Enzymologic ; Gene Expression Regulation, Neoplastic ; Genes, Reporter ; Humans ; Luciferases ; genetics ; Male ; Matrix Metalloproteinase 2 ; genetics ; metabolism ; Mutagenesis, Site-Directed ; Promoter Regions, Genetic ; Prostatic Neoplasms ; enzymology ; RNA, Messenger ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Sequence Deletion

OBJECTIVETo study the role of PAK6 in prostate cancer by cloning PAK6-N terminal sequence into E.coli and preparing its polyclonal rabbit antibody to detect PAK6 expression in prostate cancer.

METHODSBased on human PAK6 cDNA sequence, we designed a pair of primers to amplify the PAK6-N terminal sequence by PCR. The PCR product was subcloned into the bacterial expression vector pGEX-4T-1 via EcoRI/XhoI sites, and the recombinant plasmids were identified by enzymatic cleavage followed by DNA sequence analysis. By transforming the expression vector into component E.coli BL21 cells, the GST-PAK6-N fusion protein was expressed with IPTG induction. Glutathione-Sepharose beads were used to purify GST- PAK6-N fusion protein. Anti-PAK6 polyclonal antibody was produced by immunizing rabbits with purified GST-PAK6 N-terminal fusion protein. Anti-PAK6 polyclonal antibody was purified by protein A beads and used for detection of PAK6 expression in 3 prostate cancer specimens.

RESULTS AND CONCLUSIONWe cloned PAK6-N terminal gene fragment successfully, purified GST-PAK6 N-terminal fusion protein, and obtained polyclonal rabbit PAK6 antibody. Immunohistochemistry indicated that PAK6 expressed in the stroma instead of the cancer cells in prostate cancer. All of the 3 prostate cancer specimens showed positive staining in the stroma, suggesting that PAK6 may participate in the stroma-cancer cell interaction in prostate cancer.

Aged ; Animals ; Antibodies, Monoclonal ; immunology ; isolation & purification ; Cloning, Molecular ; DNA, Complementary ; chemistry ; genetics ; Electrophoresis, Polyacrylamide Gel ; Gene Expression Regulation, Enzymologic ; Gene Expression Regulation, Neoplastic ; Humans ; Immunohistochemistry ; Male ; Polymerase Chain Reaction ; Prostatic Neoplasms ; enzymology ; genetics ; Rabbits ; Recombinant Fusion Proteins ; immunology ; metabolism ; Sequence Analysis, DNA ; p21-Activated Kinases ; genetics ; immunology ; metabolism

AIMTo investigate the possible role of manganese in the regulation of mitochondrial aconitase (mACON) activity human prostate carcinoma cell line PC-3 cells.

METHODSThe mACON enzymatic activities of human prostate carcinoma cell line PC-3 cells were determined using a reduced nicotinamide adenine dinucleotide-coupled assay. Immunoblot and transient gene expression assays were used to study gene expression of the mACON. The putative response element for gene expression was identified using reporter assays with site-directed mutagenesis and electrophoretic mobility-shift assays.

RESULTSIn vitro study revealed that manganese chloride (MnCl2) treatment for 16 h inhibited the enzymatic activity of mACON, which induced the inhibition of citrate utility and cell proliferation of PC-3 cells. Although results from transient gene expression assays showed that MnCl2 treatment upregulated gene translation by approximately 5-fold through the iron response element pathway, immunoblot and reporter assays showed that MnCl2 treatments inhibited protein and gene expression of mACON. This effect was reversed by co-treatment with ferric ammonium citrate. Additional reporter assays with site-directed mutagenesis and electrophoretic mobility-shift assays suggested that a putative metal response element in the promoter of the mACON gene was involved in the regulation of MnCl2 on the gene expression of mACON.

CONCLUSIONThese findings suggest that manganese acts as an antagonist of iron, disrupting the enzymatic activity and gene expression of mACON and citrate metabolism in the prostate.

Aconitate Hydratase ; antagonists & inhibitors ; genetics ; Actins ; genetics ; Adenosine Triphosphate ; metabolism ; Cell Line, Tumor ; Chlorides ; pharmacology ; Citrates ; metabolism ; DNA Primers ; Gene Expression Regulation, Enzymologic ; drug effects ; Gene Expression Regulation, Neoplastic ; drug effects ; Genes, Reporter ; Humans ; Iron ; metabolism ; Male ; Manganese Compounds ; pharmacology ; Mitochondria ; enzymology ; Prostatic Neoplasms ; enzymology