Posterior lumbar vein off the retrohepatic inferior vena cava: a novel anatomical variant with surgical implications.

PURPOSE: Resection of tumors involving the inferior vena cava requires vascular control of posteriorly draining lumbar veins to ensure a bloodless field. Surgical texts and atlases assert that lumbar veins do not insert into the inferior vena cava superior to the renal hilum. However, at our institution we have encountered patients undergoing inferior vena cava tumor thrombectomy who have a posterior lumbar vein cephalad to the renal veins. Since this represents an unrecognized source of hemorrhage, we investigated the frequency of a superior lumbar vein in cadaveric dissection. MATERIALS AND METHODS: Retroperitoneal cadaveric dissection of the inferior vena cava was done to assess the frequency of a lumbar vein draining into the inferior vena cava cephalad to the renal veins. RESULTS: Of the 49 cadaveric dissections performed 19 (38.8%) showed a single posterior lumbar vein between the diaphragm and the renal hilum. Of these 19 cadavers 15 (78.9%) were male. This vein was located an average ± SD of 7.4 ± 0.6 cm cephalad to the right renal vein and it was 3.7 ± 1.6 cm in diameter. In all cadavers this vein inserted within 30 degrees to the left or right of the posterior (also termed dorsal) aspect of the inferior vena cava. CONCLUSIONS: The identification of a lumbar vein between the renal hilum and the diaphragm represents an important anatomical variant that occurs in a significant percent of individuals. Surgeons will benefit from the knowledge of this variant of inferior vena cava vasculature and should anticipate the presence of this vein to prevent unnecessary morbidity and mortality secondary to unexpected hemorrhage, particularly in male patients.

Active sonic hedgehog signaling between androgen independent human prostate cancer cells and normal/benign but not cancer-associated prostate stromal cells.

BACKGROUND: 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. METHODS: 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. RESULTS: 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 CONCLUSIONS: 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.

Expression of C-reactive protein and cyclooxygenase enzyme-2 in clear cell renal cell carcinoma: correlation with pathological parameters in 110 patients.

C-reactive protein is produced in response to cytokines such as interleukin (IL)-6. It is known that increased plasma IL-6 levels induce increased hepatic and intratumoral production of C-reactive protein. Cyclooxygenase enzyme-2 is induced by various stimuli, including inflammation and various growth factors. Expression of these two markers has not been well studied in clear cell renal cell carcinoma. The objective of this study is to correlate the expression of C-reactive protein and cyclooxygenase enzyme-2 in clear cell renal cell carcinoma with pathologic parameters. A search of the surgical pathology and consultation files at our institution was performed for nephrectomy specimens with clear cell renal cell carcinoma from 2007 to 2008. Immunohistochemical stains for C-reactive protein and cyclooxygenase enzyme-2 were performed. Staining intensity was graded as 0, 1+, 2+, and 3+. The staining intensity was then correlated with pathologic stage and Fuhrman nuclear grade for each case. A total of 110 cases were identified. Strong expression of C-reactive protein was associated with higher Fuhrman nuclear grade and pathologic stage, and the strength of correlation was statistically significant (p = 0.01 and p = 0.001), respectively. However, cyclooxygenase enzyme-2 expression did not show statistically significant correlation with both pathologic stage and Fuhrman nuclear grade (p = 0.1 and p = 0.15), respectively. To our knowledge, this is the largest study to date correlating the expression of both C-reactive protein and cyclooxygenase enzyme-2 in tissue with pathologic parameters in patients with clear cell renal cell carcinoma, which could have significant prognostic and therapeutic implications.

Vascular endothelial growth factor regulates myeloid cell leukemia-1 expression through neuropilin-1-dependent activation of c-MET signaling in human prostate cancer cells.

BACKGROUND: Myeloid cell leukemia-1 (Mcl-1) is a member of the Bcl-2 family, which inhibits cell apoptosis by sequestering pro-apoptotic proteins Bim and Bid. Mcl-1 overexpression has been associated with progression in leukemia and some solid tumors including prostate cancer (PCa). However, the regulatory mechanism for Mcl-1 expression in PCa cells remains elusive. RESULTS: Immunohistochemical analyses revealed that Mcl-1 expression was elevated in PCa specimens with high Gleason grades and further significantly increased in bone metastasis, suggesting a pivotal role of Mcl-1 in PCa metastasis. We further found that vascular endothelial growth factor (VEGF) is a novel regulator of Mcl-1 expression in PCa cells. Inhibition of endogenous Mcl-1 induced apoptosis, indicating that Mcl-1 is an important survival factor in PCa cells. Neuropilin-1 (NRP1), the "co-receptor" for VEGF165 isoform, was found to be highly expressed in PCa cells, and indispensible in the regulation of Mcl-1. Intriguingly, VEGF165 promoted physical interaction between NRP1 and hepatocyte growth factor (HGF) receptor c-MET, and facilitated c-MET phosphorylation via a NRP1-dependent mechanism. VEGF165 induction of Mcl-1 may involve rapid activation of Src kinases and signal transducers and activators of transcription 3 (Stat3). Importantly, NRP1 overexpression and c-MET activation were positively associated with progression and bone metastasis in human PCa specimens and xenograft tissues. CONCLUSIONS: This study demonstrated that Mcl-1 overexpression is associated with PCa bone metastasis. Activation of VEGF165-NRP1-c-MET signaling could confer PCa cells survival advantages by up-regulating Mcl-1, contributing to PCa progression.

Differential expression of the alpha2 chain of the interleukin-13 receptor in metastatic human prostate cancer ARCaPM cells.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Phorbol ester phorbol-12-myristate-13-acetate induces epithelial to mesenchymal transition in human prostate cancer ARCaPE cells.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Progressive epithelial to mesenchymal transitions in ARCaP E prostate cancer cells during xenograft tumor formation and metastasis.

BACKGROUND: The mechanism of epithelial to mesenchymal transition (EMT) could be adopted by tumor cells for migration and invasion. We have reported that ARCaP(E) human prostate cancer cells undergo EMT-like changes during xenograft growth in athymic mice. METHODS: In this report, we assessed the extent of EMT by tracking changes in cloned ARCaP(E) cells expressing red fluorescence protein during successive orthotopic prostate tumor formation. Cancer cells with stromal-like morphology were isolated and examined for EMT-like changes. RESULTS: EMT-like morphologic and expression changes were detected after one round of in vivo tumor formation. Importantly, when recovered tumor cells were used in second round xenograft tumor formation, a large fraction of ARCaP(E) cells showed drastic EMT-like changes, with markedly enlarged cell size and divergent cell shapes similar to those of mesenchymal stromal cells. The morphologic change was accompanied by increased growth and metastasis, as tumor incidence increased while red fluorescent tumor cells could be detected from circulating blood, bone marrow, peritoneal ascites, and lung of the tumor-bearing mice. Recovered clones from these samples had lost epithelial markers but many showed activated stromal marker vimentin expression. The EMT appeared permanent since the newly acquired morphology was sustained after continuous passages. CONCLUSIONS: Results from this study demonstrate that through interaction with the host tumor microenvironment, cancer cells acquire cellular plasticity. During xenograft tumor formation and metastasis, a single clone of cancer cells could yield a heterogeneous population, with a substantial number of tumor cells adopting mesenchymal stroma-like phenotypes.

Soluble factors derived from stroma activated androgen receptor phosphorylation in human prostate LNCaP cells: roles of ERK/MAP kinase.

BACKGROUND: Accumulated evidence suggests stromal-epithelial interactions are critical to the progression of prostate cancer. In this study, we characterized AR phosphorylation in LNCaP cells co-cultured with the conditioned medium (CM) from human prostate stromal fibroblasts. METHODS: CM harvested from prostate stromal fibroblasts was added to LNCaP cells, and both anchorage-dependent and -independent growth was determined. Status of AR phosphorylation at Ser-81 and Ser-213 was assessed by immunoblot analysis. ERK kinase activity was measured using MBP-2 protein as the substrate. RESULTS: The growth of LNCaP cells on plastic dishes increased by 1.7-fold upon exposure to stromal CM or androgen, and their combination resulted in additive growth (2.4-fold). Anchorage-independent growth of LNCaP cells in soft agar, however, was induced synergistically at 80-fold by both stromal CM and androgen. Stromal CM or androgen alone induced LNCaP cell growth by 10- and 26-fold, respectively. We observed ERK kinase inhibitor, U0126, but not phosphatidylinositol 3-kinase (PI-3K), LY294002, or protein kinase A (PKA) inhibitor, H-89, inhibited stromal CM or androgen-induced PSA promoter luciferase activities, and anchorage-independent growth of LNCaP cells. Our results demonstrated for the first time how stromal CM acts in synergy with androgen by activation of ERK kinase and AR phosphorylation at Ser-81 but not Ser-213, for AR-regulated PSA promoter and anchorage-independent growth of human prostate cancer cells. CONCLUSIONS: A stromal factor-activated ERK pathway mediated by AR phosphorylation at Ser-81 could be responsible for stimulating the growth of human prostate cancer cells.

Transcription variants of the prostate-specific PrLZ gene and their interaction with 14-3-3 proteins.

We have reported isolation and characterization of the prostate-specific and androgen-regulated PrLZ gene abnormally expressed in prostate cancer. PrLZ is a potential biomarker for prostate cancer and a candidate oncogene promoting cell proliferation and survival in prostate cancer cells. A full delineation of the PrLZ gene and its gene products may provide clues to the mechanisms regulating its expression and function. In this report, we identified three additional exons in the PrLZ gene and recognized five transcript variants from alternative splicing that could be detected by RT-PCR and Western blotting. Structural comparison demonstrated that the PrLZ proteins are highly conserved among species. PrLZ contains multiple potential sites for interaction with other proteins. We used mammalian two-hybrid assays to demonstrate that PrLZ isoforms interact with 14-3-3 proteins, and multiple sites in the PrLZ may be involved in the interaction. Alternative splicing may contribute to abnormally enhanced PrLZ levels in prostate cancer, and interaction with 14-3-3 proteins may be a mechanism by which PrLZ promotes cell proliferation and survival during prostate cancer development and progression. This information is a valuable addition to the investigation of the oncogenic properties of the PrLZ gene.

Increased low density lipoprotein and increased likelihood of positive prostate biopsy in black americans.

PURPOSE: Differences in prostate cancer incidence, grade and stage at diagnosis, and survival in black vs nonblack men are well documented. Recent studies indicate that lipids may have a role in oncogenesis, including that of prostate cancer. We investigated the relationship between circulating lipids in black and nonblack patients, and newly diagnosed prostate cancer. MATERIALS AND METHODS: The study population included consecutive patients who underwent prostate biopsy for increased prostate specific antigen and/or abnormal digital rectal examination at Atlanta Veterans Affairs Medical Center. Age, race, prostate specific antigen, prostate volume, body mass index, family history, high and low density lipoprotein, triglyceride and cholesterol lowering medications were included in data analysis. RESULTS: A total of 1,775 men with complete information were included in data analysis. A total of 521 black and 451 white men had positive biopsies. Using 100 mg/dl or less as the referent the adjusted OR reflecting the association of low density lipoprotein and prostate cancer diagnosis in black men was 1.49 (95% CI 1.04-2.13, p = 0.031), 1.51 (95% CI 0.96-2.39, p = 0.076) and 3.24 (95% CI 1.59-6.92, p = 0.002) for low density lipoprotein greater than 100 to 130, greater than 130 to 160 and greater than 160 mg/dl, respectively. Corresponding results in nonblack men showed no significant association. CONCLUSIONS: Increased serum low density lipoprotein is associated with an increased likelihood of prostate cancer diagnosis in black men but not in nonblack men. This association is strongest in the highest low density lipoprotein risk category. The reasons for the racial differences are unknown but may include genetic, dietary or other environmental factors.

The utilization of Gleason grade as the primary criterion for ordering nuclear bone scan in newly diagnosed prostate cancer patients.

Utilization of nuclear bone scans for staging newly diagnosed prostate cancer has decreased dramatically due to PSA-driven stage migration. The current criteria for performing bone scans are based on limited historical data. This study evaluates serum PSA and Gleason grade in predicting positive scans in a contemporary large series of newly diagnosed prostate cancer patients. Eight hundred consecutive cases of newly diagnosed prostate cancer over a 64-month period underwent a staging nuclear scan. All subjects had histologically confirmed cancer. The relationship between PSA, Gleason grade, and bone scan was examined by calculating series of crude, stratified, and adjusted odds ratios with corresponding 95% confidence intervals. Four percent (32/800) of all bone scans were positive. This proportion was significantly lower in patients with Gleason score or=8 (18.8%, p < 0.001). Among patients with Gleason score 30 ng/ml compared to or=8, the rate was significantly higher (27.9 vs. 0%) when PSA was >10 ng/ml compared to 30 ng/ml. However, for patients with a high Gleason score (8-10), we recommend a bone scan if the PSA is >10 ng/ml.

Quantum dots: emerging applications in urologic oncology.

Quantum dots (QDs), nanometer-sized fluorescent probes with unique optical and electronic properties, offer a promising and powerful tool for cancer imaging and diagnostics. For the past few years, QDs were actively developed for biomolecular profiling of cancer biomarkers, in vivo tumor imaging, and even targeted drug delivery. These emerging applications are currently being improved and integrated into clinical practice. In this article, we describe the development of multifunctional QDs and their potential applications in oncology, with a particular emphasis on the diagnosis, prognosis, and treatment of urologic cancers.

PrLZ is expressed in normal prostate development and in human prostate cancer progression.

PURPOSE: We previously reported the isolation and characterization of PrLZ, a novel prostate-specific and androgen-responsive gene of the tumor protein D52 family at chromosome 8q21.1. PrLZ is the only known gene in this locus with prostate specificity. Expression level of PrLZ was elevated specifically in cancer cells, suggesting its association with malignancy. EXPERIMENTAL DESIGN: To define its biological function in the morphogenesis, development, and functional maturation of the prostate gland and to gain further insight into its role in prostate cancer, we examined PrLZ expression in prostate specimens during early embryonic development and in adult tissue. RESULTS: PrLZ first appears in the nuclei of the prostate epithelia at 16 weeks of gestation before its distribution in the cytoplasm at later ages. Its expression peaks at 24 years of age, declines at 31 years of age, and maintains a minimal level in later age. On prostate cancer development, PrLZ expression is reactivated, and its expression increases from primary localized tumor to bone metastasis. Overexpression of PrLZ in prostate cancer cells accelerates their growth in vitro and tumor formation in vivo. CONCLUSION: This work identifies PrLZ as a marker for prostate cancer progression and metastasis, and its pattern of expression is suggestive of a proto-oncogene.

Pharmacological prophylaxis of venous thromboembolism in contemporary radical retropubic prostatectomy: does concomitant pelvic lymphadenectomy matter?

The prevention of venous thromboembolism is a major concern in cancer patients undergoing pelvic surgery. Radical retropubic prostatectomy is a common treatment for localized prostate cancer and has been identified as a high risk procedure for postoperative venous thromboembolism. However, most patients diagnosed with prostate cancer in the current era have clinically localized, low volume disease and the risk of venous thromboembolism is very low. Multiple guidelines exist for the prevention of venous thromboembolism in patients undergoing radical retropubic prostatectomy and pharmacological venous thromboembolism prophylaxis is recommended. Most urological surgeons in the USA however, do not routinely utilize pharmacological prophylaxis. A major concern arises when radical retropubic prostatectomy is performed with a concomitant pelvic lymphadenectomy. Pharmacological prophylaxis is known to increase the rate of lymph drainage and the rate of lymphocele formation. Evidence suggests that lymphocele may be an independent risk factor for venous thromboembolism in the postoperative period. These factors raise concern over current guidelines calling for routine use of pharmacological venous thromboembolism prophylaxis in radical retropubic prostatectomy especially when lymphadenectomy is performed simultaneously.

Endothelin-1 promotes cell survival in renal cell carcinoma through the ET(A) receptor.

Endothelin-1 (ET-1) is a potent vasoconstrictor that has been shown to significantly impact many benign and malignant tissues by signaling through its two cognate receptors: ET(A) and ET(B). As ET-1 has a role in both normal and diseased kidney, we initiated studies to investigate endothelin axis expression and function in renal cell carcinoma (RCC). In this study, relatively high levels of ET-1 were detected in all six human RCC cell lines investigated. RT-PCR and Southern analyses revealed that all six RCC cell lines expressed ET(A) receptor mRNA, while 3/6 cell lines also expressed ET(B) mRNA. High affinity ET-1 binding occurred in all but one RCC cell line and quantitative RT-PCR demonstrated ET(A) mRNA expression in all six cell lines. Methylation of the ET(B) promoter (EDNRB) in 4/6 RCC cell lines was observed, suggesting a mechanism for repressed ET(B) expression. Moreover, methylation occurred in 32/48 of renal tumors and in 27/55 of histologically normal adjacent tissue samples studied, while no methylation was evident in any normal tissue isolated from nephrectomy or at autopsy. Functionally, ET-1 significantly inhibited paclitaxel-induced apoptosis in RCC cells through binding ET(A) with the ET-1 signaling mediated via the PI3-kinase/Akt pathway. Collectively, these data support the therapeutic targeting of the ET(A) receptor as a novel treatment strategy for RCC.

Beta2-microglobulin promotes the growth of human renal cell carcinoma through the activation of the protein kinase A, cyclic AMP-responsive element-binding protein, and vascular endothelial growth factor axis.

PURPOSE: Beta(2)-microglobulin (beta2M), a soluble protein secreted by cancer and host inflammatory cells, has various biological functions, including antigen presentation. Because aberrant expression of beta2M has been reported in human renal cell carcinoma, we investigated the effects of beta2M overexpression on cancer cell growth and analyzed its molecular signaling pathway. EXPERIMENTAL DESIGN: We established clonal cell lines that overexpressed beta2M in human renal cell carcinoma (SN12C) cells and then examined cell growth in vitro and in vivo and studied the beta2M-mediated downstream cell signaling pathway. RESULTS: Our results showed that beta2M expression positively correlates with (a) in vitro growth on plastic dishes and as Matrigel colonies, (b) cell invasion and migration in Boyden chambers, and (c) vascular endothelial growth factor (VEGF) expression and secretion by cells. We found, in addition, that beta2M mediates its action through increased phosphorylation of cyclic AMP-responsive element-binding protein (CREB) via the protein kinase A-CREB axis, resulting in increased VEGF expression and secretion. In convergence with this signal axis, beta2M overexpression also activated both phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase pathways. Beta2M overexpression induced accelerated growth of SN12C in mouse subcutis and bone. Interrupting the beta2M signaling pathway using small interfering RNA led to apoptosis with increased activation of caspase-3 and caspase-9 and cleaved poly(ADP-ribose) polymerase. CONCLUSIONS: Our results showed for the first time that the beta2M-protein kinase A-CREB-VEGF signaling axis plays a crucial role in support of renal cell carcinoma growth and progression and reveals a novel therapeutic target.

Loss of HOXC6 expression induces apoptosis in prostate cancer cells.

We have performed whole genome expression profiling of 28 patient prostate tumor samples and 12 normal prostate samples and identified 55 upregulated and 60 downregulated genes significantly changed in prostate tumor samples compared to normal prostate tissues. Among the members of the upregulated gene set was the developmental transcription factor Homeobox C6 (HOXC6). Silencing of HOXC6 expression using small-interfering RNA (siRNA) resulted in decreased proliferation rates for both androgen-dependent LnCaP cells and the LnCaP-derived androgen-independent C4-2 cell line. Flow cytometry and immunoblotting for the caspase-cleaved form of poly-ADP ribose polymerase (PARP) determined that the decrease in cell numbers was due to increased apoptosis. To validate the specificity of the siRNA-induced apoptosis, LnCaP cells were cotransfected with siRNA specific to the HOXC6 3'UTR and a mammalian expression vector containing the HOXC6 open reading frame, but lacking the 3'UTR. Overexpression of HOXC6 rescued the LnCaP cells from HOXC6 siRNA-induced apoptosis, and increased growth of control GFP siRNA-transfected cells. Expression profiling of HOXC6 siRNA transfections and HOXC6 overexpression identified neutral endopeptidase (NEP) and insulin-like growth factor binding protein-3 (IGFBP-3) as potential proapoptotic repression targets of HOXC6. Our data suggest that HOXC6 may be a novel potential therapeutic target for prostate cancer.

In vivo molecular and cellular imaging with quantum dots.

Quantum dots (QDs), tiny light-emitting particles on the nanometer scale, are emerging as a new class of fluorescent probe for in vivo biomolecular and cellular imaging. In comparison with organic dyes and fluorescent proteins, QDs have unique optical and electronic properties: size-tunable light emission, improved signal brightness, resistance against photobleaching, and simultaneous excitation of multiple fluorescence colors. Recent advances have led to the development of multifunctional nanoparticle probes that are very bright and stable under complex in vivo conditions. A new structural design involves encapsulating luminescent QDs with amphiphilic block copolymers and linking the polymer coating to tumor-targeting ligands and drug delivery functionalities. Polymer-encapsulated QDs are essentially nontoxic to cells and animals, but their long-term in vivo toxicity and degradation need more careful study. Bioconjugated QDs have raised new possibilities for ultrasensitive and multiplexed imaging of molecular targets in living cells, animal models and possibly in humans.

PrLZ, a novel prostate-specific and androgen-responsive gene of the TPD52 family, amplified in chromosome 8q21.1 and overexpressed in human prostate cancer.

We report a previously unrecognized prostate-specific protein, PrLZ (prostate leucine zipper), a new member of the Tumor Protein D52 (TPD52) family. The gene for PrLZ was localized at chromosome 8q21.1, a locus most frequently amplified in human prostate cancer. Multiple tissue analyses demonstrated PrLZ predominantly in the prostate gland. Although its expression was enhanced by androgens in androgen receptor-expressing cells, PrLZ was detected in all of the human prostate cancer cell lines, regardless of androgen receptor status. Monoclonal anti-PrLZ antibodies were produced and intense immunohistochemical staining of PrLZ was observed in prostate epithelial cells in intraepithelial neoplasia and prostate cancer, whereas lower-level staining was detected in normal and benign epithelial components of the prostate gland. As the only prostate-specific gene identified in the most frequently amplified genomic region in prostate cancer, PrLZ may be the link between chromosome 8q amplification and malignant transformation of the prostate epithelia.