Biomedical subjects

Robert L Vessella

Publications and source records attributed to Robert L Vessella.

At least 19 recordsLinked to original sources

PubMed2006

Mutation screening of the androgen receptor promoter and untranslated regions in prostate cancer.

BACKGROUND: Mechanisms, other than gene amplification, leading to overexpression of AR in androgen ablation-resistant prostate cancer remain unknown and could include genetic alterations in the promoter or untranslated regions (UTR) of the AR gene. MATERIALS AND METHODS: DNAs from five prostate cancer cell lines, 19 LuCaP xenografts, 44 clinical tumors, and 36 non-malignant controls were used for screening mutations in the upstream regulatory region, promoter and the 5'- and 3'-UTRs of the AR gene with denaturating high performance liquid chromatography (DHPLC) and sequencing. RESULTS: Ten different sequence variations were found in prostate cancer cell lines and xenografts. However, none of them were recurrent or were found in clinical prostate cancer specimens or in normal controls. CONCLUSIONS: Recurrent mutations in the promoter or UTRs of AR seem to be rare, and thus not likely mechanisms for the increased expression of the gene in the androgen ablation-resistant prostate cancer.

Adenocarcinoma↗

PubMed2006

Targeting factors involved in bone remodeling as treatment strategies in prostate cancer bone metastasis.

Prostate cancer is the most commonly diagnosed cancer in men within the western world and the third leading cause of cancer-related deaths. Even if the cancer is considered localized to the prostate, there is a 15% to 20% incidence of subsequent metastatic disease. Prostate cancer has a very high proclivity for metastasizing to bone, with approximately 90% of men with advanced disease having skeletal lesions. The prostate cancer metastases are characteristically osteoblastic, with extensive new bone deposition, unlike other tumors that metastasize to bone and cause an osteolytic response reflective of bone degradation. There are a considerable number of studies relating to inhibition of the osteoblastic response, including interference with endothelin-1, bone morphogenetic proteins, and Wnt signaling pathways. Within the past few years, several studies showed that increased osteolytic activity also occurs in the background of the prostate cancer skeletal metastases. Because growth factors are being released from the bone matrix during degradation, it suggests that inhibition of osteolysis might be effective in slowing tumor growth. Several strategies are being developed and applied to affect directly the osteolytic events, including use of bisphosphonates and targeting the critical biological regulators of osteoclastogenesis, receptor activator of nuclear factor-kappaB and receptor activator of nuclear factor-kappaB ligand. This review focuses on several of the clinical and preclinical strategies to inhibit the growth of prostate cancer cells in bone and to alleviate the multitude of associated skeletal-related events.

Animals↗

PubMed2006

Advances in treating metastatic bone cancer: summary statement for the First Cambridge Conference.

The First Cambridge Conference on Advances in Treating Metastatic Bone Cancer, a symposium held in Cambridge, Massachusetts, October 28 to 29, 2005, was convened to discuss recent advances and research related to the natural history of bone metastases and skeletal complications, bone cancer biology, treatment of myeloma and other solid tumors, and treatment-induced bone loss. The conference format combined brief presentations with extended periods of discussion. The conclusions reached during the 2-day meeting are summarized in this article and presented in more detail in the individual articles and accompanying discussion sessions that comprise the conference proceedings.

Bone Neoplasms↗

PubMed2006

Genetic aberrations in prostate cancer by microarray analysis.

The aim of this study was to screen genetic as well as expression alterations in prostate cancer. Array comparative genomic hybridization (aCGH) to a 16K cDNA microarray was performed to analyze DNA sequence copy number alterations in 5 prostate cancer cell lines and 13 xenografts. The aCGH confirmed the previously implicated common gains and losses, such as gains at 1q, 7, 8q, 16p and 17q and losses at 2q, 4p/q, 6q, 8p, 13q, 16q, 17p and 18q, which have previously been identified by chromosomal CGH (cCGH). Because of the higher resolution of aCGH, the minimal commonly altered regions were significantly narrowed-down. For example, the gain of 8q was mapped to three independent regions, 8q13.3-q21.11, 8q22.2 and 8q24.13-q24.3. In addition, a novel recurrent gain at 9p13-q21 was identified. The concomitant expression analysis indicated that genome-wide DNA sequence copy number (gene dosage) was significantly associated with the expression level (p < 0.0001). The analyses indicated several individual genes whose expression was associated with the gene copy number. For example, gains of PTK2 and FZD6, were associated with the increased expression, whereas losses of TNFRSF10B (alias DR5) and ITGA4 with decreased expression. In conclusion, the aCGH mapping data will aid in the identification of genes altered in prostate cancer. The combined expression and copy number analysis suggested that even a low-level copy number change may have significant effect on gene expression, and thus on the development of prostate cancer.

Animals↗

PubMed2006

Screening of genetic and expression alterations of SRC1 gene in prostate cancer.

BACKGROUND: Genetic alterations of the SRC1 gene have not been thoroughly studied in prostate cancer. MATERIALS AND METHODS: Five prostate cancer cell lines and 32 xenografts were screened for mutations and gene copy number alterations. Subsequently, frequencies of detected sequence variations were further analyzed in 44 clinical prostate cancers, 6 benign prostate hyperplasias, and 48 normal controls. Finally, the protein expression of SRC1 in 254 clinical prostate tumors was investigated. RESULTS: Three non-recurrent sequence variations, and one single nucleotide polymorphism in the coding region of SRC1, as well as one case of SRC1 gene amplification were found. The protein expression of SRC1 was higher in androgen ablation resistant than untreated prostate carcinomas, but the difference was not statistically significant (P = 0.0796). CONCLUSIONS: Genetic alterations of SRC1 are rare in prostate cancer. The nuclear protein accumulation of SRC1 seems to be mildly increased in androgen ablation resistant prostate cancers. .

Androgen Antagonists↗

PubMed2006

FOXO1A is a candidate for the 13q14 tumor suppressor gene inhibiting androgen receptor signaling in prostate cancer.

Chromosomal deletion is frequent at the region between BRCA2 and RB1 in the q14 band of chromosome 13 (13q14) in human cancers, including prostate cancer, suggesting the presence of a tumor suppressor gene. However, no reasonable candidate has been identified thus far. In this study, we did genetic and functional analyses to identify and evaluate the 13q14 tumor suppressor gene. Hemizygous and homozygous deletions in cell lines/xenografts of prostate cancer mapped the deletion locus to 919 kb, which harbors only one known gene, the FOXO1A transcription factor. Deletion at FOXO1A was detected in 31% to 34% in 6 cell lines, 27 xenografts, and 72 clinical specimens of prostate cancer, and was significantly more frequent than deletions at surrounding loci. In addition, FOXO1A was transcriptionally down-regulated in some prostate cancers. Functionally, ectopic expression of FOXO1A inhibited, and its knockdown promoted, cell proliferation or survival. Furthermore, FOXO1A inhibited androgen- and androgen receptor-mediated gene regulation and cell proliferation. Consistent with the understanding of FOXO1A biology, our findings suggest that FOXO1A is the 13q14 tumor suppressor gene, at least in prostate cancer. As a well-established negative effector in the phosphatidylinositol 3-kinase/AKT signaling pathway, FOXO1A inactivation in cancer would impair the therapeutic effect of phosphatidylinositol 3-kinase/AKT inhibitors in cancer treatment.

Androgen Receptor Antagonists↗

PubMed2006

Microsatellite instability and mismatch repair target gene mutations in cell lines and xenografts of prostate cancer.

BACKGROUND: Mismatch repair (MMR) and microsatellite instability (MSI) occur in prostate cancer, but their role has not been well documented. METHODS: In 6 cell lines and 22 xenografts from prostate cancer, PCR and gel electrophoresis were performed to detect MSI by analyzing microsatellite markers BAT-25 and BAT-26 and to detect frameshift mutations in mononucleotide repeats in BAX, IGF2R, MSH3, MSH6, and TGFBR2. RESULTS: Four of 6 (67%) cell lines and 3 of 22 (14%) xenografts showed MSI. At least 1 frameshift mutation was detected in the same 4 (67%) cell lines and in 5 of 22 (23%) xenografts. While MSH3 was frequently mutated in cell lines, BAX and TGFBR2 showed frequent alterations in both cell lines and xenografts. CONCLUSIONS: MSI related to MMR deficiency is relatively frequent in high-grade tumors, and mutations in MSI target genes involved in cell death and proliferation appeared to be selected for during prostatic carcinogenesis.

Animals↗

PubMed2006

Administration of zoledronic acid enhances the effects of docetaxel on growth of prostate cancer in the bone environment.

BACKGROUND: After development of hormone-refractory metastatic disease, prostate cancer is incurable. The recent history of chemotherapy has shown that with difficult disease targets, combinatorial therapy frequently offers the best chance of a cure. In this study we have examined the effects of a combination of zoledronic acid (ZOL), a new-generation bisphosphonate, and docetaxel on LuCaP 23.1, a prostate cancer xenograft that stimulates the osteoblastic reaction when grown in the bone environment. METHODS: Intra-tibial injections of LuCaP 23.1 cells were used to generate tumors in the bone environment, and animals were treated with ZOL, docetaxel, or a combination of these. Effects on bone and tumor were evaluated by measurements of bone mineral density and histomorphometrical analysis. RESULTS: ZOL decreased proliferation of LuCaP 23.1 in the bone environment, while docetaxel at a dose that effectively inhibited growth of subcutaneous tumors did not show any effects in the bone environment. The combination of the drugs significantly inhibited the growth of LuCaP 23.1 tumors in the bone. CONCLUSION: In conclusion, the use of the osteolysis-inhibitory agent ZOL in combination with docetaxel inhibits growth of prostate tumors in bone and represents a potential treatment option.

Animals↗

PubMed2006

The gene for polycomb group protein enhancer of zeste homolog 2 (EZH2) is amplified in late-stage prostate cancer.

Overexpression of the polycomb group protein enhancer of zeste homologue 2 (EZH2) has been found in several malignancies, including prostate cancer, with an aggressive phenotype. Amplification of the gene has previously been demonstrated in several malignancies, but not in prostate cancer. Our goal was to evaluate the gene copy number and expression alterations of EZH2 in prostate cancer. The copy number of EZH2 in cell lines (LNCaP, DU145, PC-3, 22Rv1), xenografts (n = 10), and clinical tumors (n = 191) was studied with fluorescence in situ hybridization. All cell lines had a gain of EZH2. Eight of the ten xenografts showed an increased copy number of the gene, including one case of high-level amplification (>or=5 copies of the gene and EZH2/centromere ratio >or=2). 34/125 (27%) of untreated prostate carcinomas showed increased copy number, but only one case of low-level amplification (>or=5 copies of the gene and EZH2/centromere ratio <2), whereas half (25/46) of the hormone-refractory carcinomas showed increased copy number, including seven cases of low-level amplification and three cases of high-level amplification (P < 0.0001). Expression of EZH2 was significantly (P = 0.0009) higher in hormone-refractory prostate cancer compared with that in benign prostatic hyperplasia or untreated cancer, according to quantitative real-time RT-PCR assay. Also, the expression of EZH2 protein was found to be higher in hormone-refractory tumors than in hormone-naïve tumors by immunohistochemistry. The EZH2 gene amplification was significantly (P < 0.05) associated with increased EZH2 protein expression. The data show that amplification of the EZH2 gene is rare in early prostate cancer, whereas a fraction of late-stage tumors contains the gene amplification leading to the overexpression of the gene, thus indicating the importance of EZH2 in the progression of prostate cancer.

Cell Line, Tumor↗

PubMed2006

Telomerase activity in disseminated prostate cancer cells.

OBJECTIVE: To analyse telomerase activity in disseminated prostate cancer cells isolated from bone marrow aspirates taken from men with localized prostate cancer before radical prostatectomy (RP). PATIENTS AND METHODS: Disseminated epithelial prostate cancer cells were isolated from bone marrow aspirates from 69 men with localized prostate cancer before RP, by magnetic column-chromatography enrichment, followed by isolation of fluorescently labelled epithelial cells by micropipetting. We used pools of 10 non-epithelial bone marrow cells after tumour cell enrichment as control samples. These pure cell pools were tested for the presence of telomerase activity. RESULTS: In all, 49 of the patient samples contained disseminated prostate cancer cells. Homogeneous pools of 10 cells were obtained from 35 of these; 49% of the 35 specimens showed telomerase activity, whereas all five control samples did not. Telomerase activity in the 35 samples was not significantly associated with Gleason score, preoperative prostate-specific antigen level, tumour stage, or surgical margin status. Follow-up is continuing to assess an association with disease recurrence. CONCLUSION: This work shows the feasibility of isolating disseminated cancer cells for analysing individual or pooled cells. Compared to tissue staining, where telomerase is detected in 80-90% of samples, we found lower rates of telomerase activity in the disseminated tumour cells (49%). Telomerase-negative cells might provide information about cell dormancy, as telomerase is a marker of cell proliferation in immortal and cancer cells. Telomerase-positive cells might predict early disease recurrence, but a longer follow-up is needed to test this possibility.

Bone Marrow↗

PubMed2006

Inhibition of androgen-independent prostate cancer by estrogenic compounds is associated with increased expression of immune-related genes.

The clinical utility of estrogens for treating prostate cancer (CaP) was established in the 1940s by Huggins. The classic model of the anti-CaP activity of estrogens postulates an indirect mechanism involving the suppression of androgen production. However, clinical and preclinical studies have shown that estrogens exert growth-inhibitory effects on CaP under low-androgen conditions, suggesting additional modes whereby estrogens affect CaP cells and/or the microenvironment. Here we have investigated the activity of 17beta estradiol (E2) against androgen-independent CaP and identified molecular alterations in tumors exposed to E2. E2 treatment inhibited the growth of all four androgen-independent CaP xenografts studied (LuCaP 35V, LuCaP 23.1AI, LuCaP 49, and LuCaP 58) in castrated male mice. The molecular basis of growth suppression was studied by cDNA microarray analysis, which indicated that multiple pathways are altered by E2 treatment. Of particular interest are changes in transcripts encoding proteins that mediate immune responses and regulate androgen receptor signaling. In conclusion, our data show that estrogens have powerful inhibitory effects on CaP in vivo in androgen-depleted environments and suggest novel mechanisms of estrogen-mediated antitumor activity. These results indicate that incorporating estrogens into CaP treatment protocols could enhance therapeutic efficacy even in cases of advanced disease.

Animals↗

PubMed2005

Stromal mesenchyme cell genes of the human prostate and bladder.

BACKGROUND: Stromal mesenchyme cells play an important role in epithelial differentiation and likely in cancer as well. Induction of epithelial differentiation is organ-specific, and the genes responsible could be identified through a comparative genomic analysis of the stromal cells from two different organs. These genes might be aberrantly expressed in cancer since cancer could be viewed as due to a defect in stromal signaling. We propose to identify the prostate stromal genes by analysis of differentially expressed genes between prostate and bladder stromal cells, and to examine their expression in prostate cancer. METHODS: Immunohistochemistry using antibodies to cluster designation (CD) cell surface antigens was first used to characterize the stromas of the prostate and bladder. Stromal cells were prepared from either prostate or bladder tissue for cell culture. RNA was isolated from the cultured cells and analyzed by DNA microarrays. Expression of candidate genes in normal prostate and prostate cancer was examined by RT-PCR. RESULTS: The bladder stroma was phenotypically different from that of the prostate. Most notable was the presence of a layer of CD13+ cells adjacent to the urothelium. This structural feature was also seen in the mouse bladder. The prostate stroma was uniformly CD13-. A number of differentially expressed genes between prostate and bladder stromal cells were identified. One prostate gene, proenkephalin (PENK), was of interest because it encodes a hormone. Secreted proteins such as hormones and bioactive peptides are known to mediate cell-cell signaling. Prostate stromal expression of PENK was verified by an antibody raised against a PENK peptide, by RT-PCR analysis of laser-capture microdissected stromal cells, and by database analysis. Gene expression analysis showed that PENK expression was down-regulated in prostate cancer. CONCLUSION: Our findings show that the histologically similar stromas of the prostate and bladder are phenotypically different, and express organ-specific genes. The importance of these genes in epithelial development is suggested by their abnormal expression in cancer. Among the candidates is the hormone PENK and the down-regulation of PENK expression in cancer suggests a possible association with cancer development.

Cells, Cultured↗

PubMed2005

Increased Hsp27 after androgen ablation facilitates androgen-independent progression in prostate cancer via signal transducers and activators of transcription 3-mediated suppression of apoptosis.

One strategy to improve therapies in prostate cancer involves targeting cytoprotective genes activated by androgen withdrawal to delay the emergence of the androgen-independent (AI) phenotype. The objectives of this study were to define changes in Hsp27 levels after androgen ablation and to evaluate the functional relevance of these changes in AI progression. Using a tissue microarray of 232 specimens of hormone-naïve and post-hormone ablation-treated prostate cancer, we found that Hsp27 levels increase after androgen ablation to become highly expressed (>4-fold, P < or = 0.01) in AI tumors. Hsp27 overexpression rendered LNCaP cells highly resistant to androgen withdrawal both in vitro and in vivo. Tumor volume and serum prostate-specific antigen levels increased 4.3- and 10-fold faster after castration when Hsp27 was overexpressed. Treatment of LNCaP tumor cells in vitro with Hsp27 antisense oligonucleotides (ASO) or short-interfering RNA suppressed Hsp27 levels in a dose-dependent and sequence-specific manner increased the apoptotic sub-G0-G1 fraction and caspase-3 cleavage >2-fold, as well as decreased signal transducers and activators of transcription 3 (Stat3) levels and its downstream genes, c-fos and sPLA-2. The cytoprotection afforded by Hsp27 overexpression was attenuated by Stat3 knockdown using specific Stat3 ASO. Coimmunoprecipitation and immunofluorescence confirmed that Hsp27 interacts with Stat3 and that Stat3 levels correlated directly with Hsp27 levels. Hsp27 ASO treatment in athymic mice bearing LNCaP tumors significantly delayed LNCaP tumor growth after castration, decreasing mean tumor volume and serum prostate-specific antigen levels by 57% and 69%, respectively. These findings identify Hsp27 as a modulator of Stat3-regulated apoptosis after androgen ablation and as a potential therapeutic target in advanced prostate cancer.

Animals↗

PubMed2005

Application of Affymetrix array and Massively Parallel Signature Sequencing for identification of genes involved in prostate cancer progression.

BACKGROUND: Affymetrix GeneChip Array and Massively Parallel Signature Sequencing (MPSS) are two high throughput methodologies used to profile transcriptomes. Each method has certain strengths and weaknesses; however, no comparison has been made between the data derived from Affymetrix arrays and MPSS. In this study, two lineage-related prostate cancer cell lines, LNCaP and C4-2, were used for transcriptome analysis with the aim of identifying genes associated with prostate cancer progression. METHODS: Affymetrix GeneChip array and MPSS analyses were performed. Data was analyzed with GeneSpring 6.2 and in-house perl scripts. Expression array results were verified with RT-PCR. RESULTS: Comparison of the data revealed that both technologies detected genes the other did not. In LNCaP, 3,180 genes were only detected by Affymetrix and 1,169 genes were only detected by MPSS. Similarly, in C4-2, 4,121 genes were only detected by Affymetrix and 1,014 genes were only detected by MPSS. Analysis of the combined transcriptomes identified 66 genes unique to LNCaP cells and 33 genes unique to C4-2 cells. Expression analysis of these genes in prostate cancer specimens showed CA1 to be highly expressed in bone metastasis but not expressed in primary tumor and EPHA7 to be expressed in normal prostate and primary tumor but not bone metastasis. CONCLUSION: Our data indicates that transcriptome profiling with a single methodology will not fully assess the expression of all genes in a cell line. A combination of transcription profiling technologies such as DNA array and MPSS provides a more robust means to assess the expression profile of an RNA sample. Finally, genes that were differentially expressed in cell lines were also differentially expressed in primary prostate cancer and its metastases.

Cell Line, Tumor↗

PubMed2005

Prostate stem cell antigen is overexpressed in prostate cancer metastases.

PURPOSE: Prostate stem cell antigen (PSCA) is expressed by a majority of prostate cancers and is a promising therapeutic target. PSCA protein and mRNA expression was examined in prostate cancer bone, lymph node, and visceral metastases to assess the potential of PSCA as an immunotherapeutic target in advanced prostate cancer. EXPERIMENTAL DESIGN: Immunohistochemical analysis of PSCA protein expression and quantitative mRNA expression analysis of PSCA was done on clinical specimens of prostate cancer bone, lymph node, and visceral metastases. PSCA protein and mRNA expression levels were quantified and compared between available matched pairs of bone and lymph node or visceral metastases. RESULTS: Bone metastases stained with higher intensity of PSCA compared with lymph node or liver metastases in seven of eight (87.5%) matched pairs (P = 0.035). PSCA mRNA expression was equal or greater than that of LAPC-9, a PSCA expressing xenograft, in 12 of 24 (50%) cases of prostate cancer metastases and was significantly correlated with PSCA protein expression (sigma = 0.84, P = 0.0019). Overall, PSCA protein expression was detected in 41 of 47 (87.2%), four of six (66.7%), and two of three (66.7%) cases of bone, lymph node, and liver metastases, respectively. Mean PSCA staining intensity was significantly higher in prostate cancer bone metastases compared with lymph node metastases (2.0 +/- 0.02 versus 0.83 +/- 0.31, P = 0.014). CONCLUSIONS: Prostate cancer metastases express PSCA. However, greater PSCA staining intensity and level of PSCA mRNA expression was associated with bone metastases compared with lymph node metastases. This study suggests that PSCA is a promising tumor marker and potential therapeutic target for patients with metastatic prostate cancer.

Antigens, Neoplasm↗

PubMed2005

Frequent somatic mutations of the transcription factor ATBF1 in human prostate cancer.

Cancer often results from the accumulation of multiple genetic alterations. Although most malignancies are sporadic, only a small number of genes have been shown to undergo frequent mutations in sporadic cancers. The long arm of chromosome 16 is frequently deleted in human cancers, but the target gene for this deletion has not been identified. Here we report that ATBF1, which encodes a transcription factor that negatively regulates AFP and MYB but transactivates CDKN1A, is a good candidate for the 16q22 tumor-suppressor gene. We narrowed the region of deletion at 16q22 to 861 kb containing ATBF1. ATBF1 mRNA was abundant in normal prostates but more scarce in approximately half of prostate cancers tested. In 24 of 66 (36%) cancers examined, we identified 22 unique somatic mutations, many of which impair ATBF1 function. Furthermore, ATBF1 inhibited cell proliferation. Hence, loss of ATBF1 is one mechanism that defines the absence of growth control in prostate cancer.

Cell Proliferation↗

PubMed2005

Osteoprotegerin in prostate cancer bone metastasis.

Osteoprotegerin (OPG), a critical regulator of osteoclastogenesis, is expressed by prostate cancer cells, and OPG levels are increased in patients with prostate cancer bone metastases. The objective of this study was to investigate the effects of OPG overexpression on prostate cancer cells and prostate cancer/bone cell interactions in vitro and in vivo. OPG-transfected C4-2 cells expressed 8.0 ng OPG per mL per 10(6) cells, whereas no OPG was detected in the media of C4-2 cells transfected with a control plasmid. OPG overexpressed by C4-2 cells protected these cells from tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis and decreased osteoclast formation. Subcutaneous OPG-C4-2 and pcDNA-C4-2 tumors exhibited similar growth and take-rate characteristics. However, when grown in bone, tumor volume was decreased in OPG-C4-2 versus pcDNA-C4-2 (P=0.0017). OPG expressed by C4-2 cells caused increases in bone mineral density (P=0.0074) and percentage of trabecular bone volume (P=0.007), and decreases in numbers of osteoblasts and osteoclasts when compared with intratibial pcDNA-C4-2 tumors (P=0.003 and P=0.019, respectively). In summary, our data show that increased expression of OPG in C4-2 cells does not directly affect proliferation of prostate cancer cells but indirectly decreases growth of C4-2 tumors in the bone environment. Our data also show that OPG expressed by C4-2 cells inhibits bone lysis associated with C4-2 bone metastasis, which results in net increases in bone volume. We therefore hypothesize that OPG expressed in prostate cancer patient bone metastases may be at least partially responsible for the osteoblastic character of most prostate cancer bone lesions.

Animals↗

PubMed2005

Amplification and overexpression of prosaposin in prostate cancer.

We identified prosaposin (PSAP) as a secreted protein expressed in androgen-independent (AI) prostate cancer cells by cloning/sequencing, after probing a PC-3 cDNA library expressed in the lambdaTriplEx phagemid expression vector with a polyclonal rabbit antibody generated against pooled human seminal plasma. PSAP is a neurotrophic molecule; its deficiency or inactivation has proved to be lethal in man and mice, and in mice, it leads to abnormal development and atrophy of the prostate gland, despite normal testosterone levels. We used Southern hybridization, quantitative real-time polymerase chain reaction, and/or single nucleotide polymorphism (SNP) array analysis, and we now report the genomic amplification of PSAP in the metastatic AI prostate cancer cell lines, PC-3, DU-145, MDA-PCa 2b, M-12, and NCI-H660. In addition, by using SNP arrays and a set of 25 punch biopsy samples of human prostate cancer xenografts (LAPC3, LuCaP 23.1, 35, 49, 58, 73, 77, 81, 86.2, 92.1, 93, 96, 105, and 115), lymph nodes, and visceral-organ metastases, we detected amplification of the PSAP locus (10q22.1) in LuCaP 58 and 96 xenografts and two lymph node metastases. In addition, AI metastatic prostate cancer cell lines C4-2B and IA8-ARCaP over-expressed PSAP mRNA without evidence of genomic amplification. Taken together with prior data that demonstrated the growth-, migration-, and invasion-promoting activities, the activation of multiple signal transduction pathways, and the antiapoptotic effect of PSAP (or one of its active domains, saposin C) in prostate cancer cells, our current observation of PSAP amplification or overexpression in prostate cancer suggests, for the first time, a role for this molecule in the process of carcinogenesis or cancer progression in the prostate.

Blotting, Western↗