Decreased Replication Ability of E1-Deleted Adenoviruses Correlates with Increased Brain Tumor Malignancy

A Renal-Clearable Activatable Molecular Probe for Fluoro-Photacoustic and Radioactive Imaging of Cancer Biomarkers

In vivo simultaneous visualization of multiple biomarkers is critical to accurately diagnose disease and decipher fundamental processes at a certain pathological evolution, which however is rarely exploited. Herein, a multimodal activatable imaging probe (P-¹²⁵ I) is reported with activatable fluoro-photoacoustic and radioactive signal for in vivo imaging of biomarkers (i.e., hepsin and prostate-specific membrane antigen (PSMA)) associated with prostate cancer diagnosis and prognosis. P-¹²⁵ I contains a near-infrared (NIR) dye that is caged with a hepsin-cleavable peptide sequence and linked with a radiolabeled PSMA-targeted ligand (PSMAL). After systemic administration, P-¹²⁵ I actively targets the tumor site via specific recognition between PSMA and PSMAL moiety and in-situ generates of activated fluoro-photoacoustic signal after reacting with hepsin to release the free dye (uncaged state). P-¹²⁵ I achieves precisely early detection of prostate cancer and renal clearance to alleviate toxicity issues. In addition, the accumulated radioactive and activated photoacoustic signal of probe correlates well with the respective expression level of PSMA and hepsin, which provides valuable foreseeability for cancer progression and prognosis. Thus, this study presents a multimodal activatable probe for early detection and in-depth deciphering of prostate cancer.

Impact of Tumor Burden on Normal Organ Distribution in Patients Imaged with CXCR4-Targeted [68Ga]Ga-PentixaFor PET/CT

Background

CXCR4-directed positron emission tomography/computed tomography (PET/CT) has been used as a diagnostic tool in patients with solid tumors. We aimed to determine a potential correlation between tumor burden and radiotracer accumulation in normal organs.

Methods

Ninety patients with histologically proven solid cancers underwent CXCR4-targeted [68Ga]Ga-PentixaFor PET/CT. Volumes of interest (VOIs) were placed in normal organs (heart, liver, spleen, bone marrow, and kidneys) and tumor lesions. Mean standardized uptake values (SUVmean) for normal organs were determined. For CXCR4-positive tumor burden, maximum SUV (SUVmax), tumor volume (TV), and fractional tumor activity (FTA, defined as SUVmean x TV), were calculated. We used a Spearman's rank correlation coefficient (ρ) to derive correlative indices between normal organ uptake and tumor burden.

Results

Median SUVmean in unaffected organs was 5.2 for the spleen (range, 2.44 – 10.55), 3.27 for the kidneys (range, 1.52 – 17.4), followed by bone marrow (1.76, range, 0.84 – 3.98), heart (1.66, range, 0.88 – 2.89), and liver (1.28, range, 0.73 – 2.45). No significant correlation between SUVmax in tumor lesions (ρ ≤ 0.189, P ≥ 0.07), TV (ρ ≥ -0.204, P ≥ 0.06) or FTA (ρ ≥ -0.142, P ≥ 0.18) with the investigated organs was found.

Conclusions

In patients with solid tumors imaged with [68Ga]Ga-PentixaFor PET/CT, no relevant tumor sink effect was noted. This observation may be of relevance for therapies with radioactive and non-radioactive CXCR4-directed drugs, as with increasing tumor burden, the dose to normal organs may remain unchanged.

Tumor-Targeting Cholesterol-Decorated DNA Nanoflowers for Intracellular Ratiometric Aptasensing

Probing endogenous molecular profiles is of fundamental importance to understand cellular function and processes. Despite the promise of programmable nucleic-acid-based aptasensors across the breadth of biomolecular detection, target-responsive aptasensors enabling intracellular detection are as of yet infrequently realized. Several challenges remain, including the difficulties in quantification/normalization of quencher-based intensiometric signals, stability issues of the probe architecture, and complex sensor operations often necessitating extensive structural modeling. Here, the biomimetic crystallization-empowered self-assembly of a tumor-targetable DNA-inorganic hybrid nanocomposite aptasensor is presented, which enables Förster resonance energy transfer (FRET)-based quantitative interpretation of changes in the cellular target abundance. Leveraging the design programmability and high-throughput fabrication of rolling circle amplification-driven DNA nanoarchitecture, this designer platform offers a method to self-assemble a robust nanosensor from a multifunctionality-encoded template that includes a cell-targeting aptamer, a ratiometric aptasensor, and a cholesterol-decorating element. Taking prostate cancer cells and intracellular adenosine triphosphate molecules as a model system, a synergistic effect in the targeted delivery by cholesterol and aptamers, and the feasibility of quantitative intracellular aptasensing are demonstrated. It is envisioned that this approach provides a highly generalizable strategy across wide-ranging target systems toward a biologically deliverable nanosensor that enables quantitative monitoring of the abundance of endogenous biomolecules.

A computationally designed chimeric antigen receptor provides a small-molecule safety switch for T-cell therapy

Approaches to increase the activity of chimeric antigen receptor (CAR)-T cells against solid tumors may also increase the risk of toxicity and other side effects. To improve the safety of CAR-T-cell therapy, we computationally designed a chemically disruptable heterodimer (CDH) based on the binding of two human proteins. The CDH self-assembles, can be disrupted by a small-molecule drug and has a high-affinity protein interface with minimal amino acid deviation from wild-type human proteins. We incorporated the CDH into a synthetic heterodimeric CAR, called STOP-CAR, that has an antigen-recognition chain and a CD3ζ- and CD28-containing endodomain signaling chain. We tested STOP-CAR-T cells specific for two antigens in vitro and in vivo and found similar antitumor activity compared to second-generation (2G) CAR-T cells. Timed administration of the small-molecule drug dynamically inactivated the activity of STOP-CAR-T cells. Our work highlights the potential for structure-based design to add controllable elements to synthetic cellular therapies.

Anti-PSMA 124I-scFvD2B as a new immuno-PET tool for prostate cancer: preclinical proof of principle

Background

Prostate cancer (PCa) is the second leading cause of cancer-related death in the Western population. The use in oncology of positron emission tomography/computed tomography (PET/CT) with emerging radiopharmaceuticals promises accurate staging of primary disease, restaging of recurrent disease and detection of metastatic lesions. Prostate-specific membrane antigen (PSMA) expression, directly related to androgen-independence, metastasis and progression, renders this tumour associate antigen a good target for the development of new radiopharmaceuticals for PET. Aim of this study was to demonstrate in a preclinical in vivo model (PSMA-positive versus PSMA-negative tumours) the targeting specificity and sensitivity of the anti-PSMA single-chain variable fragment (scFv) labelled with ¹²⁴I.

Methods

The ¹²⁴I-labeling conditions of the antibody fragment scFvD2B were optimized and assessed for purity and immunoreactivity. The specificity of ¹²⁴I-scFvD2B was tested in mice bearing PSMA-positive and PSMA-negative tumours to assess both ex-vivo biodistribution and immune-PET.

Results

The uptake fraction of ¹²⁴I-scFvD2B was very high on PSMA positive cells (range 75–91%) and highly specific and immuno-PET at the optimal time point, defined between 15 h and 24 h, provides a specific localization of lesions bearing the target antigen of interest (PSMA positive vs PSMA negative tumors %ID/g: p = 0.0198 and p = 0.0176 respectively) yielding a median target/background ratio around 30–40.

Conclusions

Preclinical in vivo results of our immuno-PET reagent are highly promising. The target to background ratio is improved notably using PET compared to SPECT previously performed.

These data suggest that, upon clinical confirmation of sensitivity and specificity, our anti-PSMA ¹²⁴I-scFvD2B may be superior to other diagnostic modalities for PCa. The possibility to combine in patients our ¹²⁴I-scFvD2B in multi-modal systems, such as PET/CT, PET/MR and PET/SPECT/CT, will provide quantitative 3D tomographic images improving the knowledge of cancer biology and treatment.

Sox7 negatively regulates prostate-specific membrane antigen (PSMA) expression through PSMA-enhancer

BACKGROUND

PSMA expression in the prostate epithelium is controlled by a cis-element, PSMA enhancer (PSME). PSME contains multiple binding sites for Sox proteins, and in this study, we identified Sox7 protein as a negative regulator of PSMA expression through its interaction with PSME.

METHODS

The statistical correlation between Sox7 and PSMA mRNA expression was evaluated using five prostate cancer studies from cBioportal. In vitro and in vivo interaction between Sox7 and PSME was evaluated by chromatin immunoprecipitation (ChIP), electrophoretic mobility shift assay (EMSA), and luciferase reporter assay. Synthetic oligonucleotides were generated to define the sites in PSME that interact with Sox7 protein. Sox7 mutants were generated to identify the region of this protein required to regulate PSMA expression. Sox7 was also stably expressed in LNCaP/C4-2 and 22Rv1 cells to validate the regulation of PSMA expression by Sox7 in vivo.

RESULTS

Sox7 mRNA expression negatively correlated with PSMA/FOLH1 and PSMAL/FOLH1B mRNA expression in Broad/Cornell, TCGA and MSKCC studies, but not in two studies containing only metastatic prostate tumors. PC-3 cells mostly expressed the 48.5 KDa isoform 2 of Sox7, and the depletion of this isoform did not restore PSMA expression. Ectopic expression of canonical, wild-type Sox7 in C4-2 and 22Rv1 cells suppressed PSMA protein expression. ChIP assay revealed that canonical Sox7 protein preferentially interacts with PSME in vivo, and EMSA identified the SOX box sites #2 and #4 in PSME as required for its interaction. Sox7 was capable of directly binding to PSME and suppressed PSME-mediated transcription. The NLS regions of Sox7, but not its β-catenin interacting motif, are essential for this suppressing activity. Furthermore, restoration of wild-type Sox7 expression but not Sox7-NLS mutant in Sox7-null prostate cancer cell lines suppressed PSMA expression.

CONCLUSIONS

The inactivation of canonical Sox7 is responsible for the upregulated expression of PSMA in non-metastatic prostate cancer.

Safe core-satellite magneto-plasmonic nanostructures for efficient targeting and photothermal treatment of tumor cells

Magneto-plasmonic nanostructures functionalized with cell targeting units are of great interest for nanobiotechnology applications. Photothermal treatment of cells targeted with antibody functionalized nanostructures and followed by magnetic isolation, allows killing selected cells and hence is one of the applications of great interest. The magneto-plasmonic nanostructures reported herein were synthesized using naked gold and magnetite nanoparticles obtained through a green approach based on laser ablation of bulk materials in water. These particles do not need purifications steps for biocompatibility and are functionalized with a SERRS (surface enhanced resonance Raman scattering) active molecule for detection and with an antibody for targeting prostate tumor cells. Quantitative results for the cell targeting and selection efficiency show an overall accuracy of 94% at picomolar concentrations. The photothermal treatment efficiently kills targeted and magneto-selected cells producing a viability below 5% after 3 min of irradiation, compared with almost 100% viability of incubated and irradiated, but non targeted cells.

Aptamer/AuNP Biosensor for Colorimetric Profiling of Exosomal Proteins

Exosomes constitute an emerging biomarker for cancer diagnosis because they carry multiple proteins that reflect the origins of parent cells. Assessing exosome surface proteins provides a powerful means of identifying a combination of biomarkers for cancer diagnosis. We report a sensor platform that profiles exosome surface proteins in minutes by the naked eye. The sensor consists of a gold nanoparticle (AuNP) complexed with a panel of aptamers. The complexation of aptamers with AuNPs protects the nanoparticles from aggregating in a high-salt solution. In the presence of exosomes, the non-specific and weaker binding between aptamers and the AuNP is broken, and the specific and stronger binding between exosome surface protein and the aptamer displaces aptamers from the AuNP surface and results in AuNP aggregation. This aggregation results in a color change and generates patterns for the identification of multiple proteins on the exosome surface.

Folic acid on iron oxide nanoparticles: platform with high potential for simultaneous targeting, MRI detection and hyperthermia treatment of lymph node metastases of prostate cancer

Folic acid directly bound to the surface of iron oxide nanoparticles with simultaneously high targeting, MRI relaxivity and heating efficacy.

Engineering chemically modified viruses for prostate cancer cell recognition

Specific detection of circulating tumor cells and characterization of their aggressiveness could improve cancer diagnostics and treatment. Metastasis results from such tumor cells, and causes the majority of cancer deaths. Chemically modified viruses could provide an inexpensive and efficient approach to detect tumor cells and quantitate their cell surface biomarkers. However, non-specific adhesion between the cell surface receptors and the virus surface presents a challenge. This report describes wrapping the virus surface with different PEG architectures, including as fusions to oligolysine, linkers, spacers and scaffolded ligands. The reported PEG wrappers can reduce by >75% the non-specific adhesion of phage to cell surfaces. Dynamic light scattering verified the non-covalent attachment by the reported wrappers as increased sizes of the virus particles. Further modifications resulted in specific detection of prostate cancer cells expressing PSMA, a key prostate cancer biomarker. The approach allowed quantification of PSMA levels on the cell surface, and could distinguish more aggressive forms of the disease.

Structure-Activity Relationship of (18)F-Labeled Phosphoramidate Peptidomimetic Prostate-Specific Membrane Antigen (PSMA)-Targeted Inhibitor Analogues for PET Imaging of Prostate Cancer

A series of phosphoramidate-based prostate specific membrane antigen (PSMA) inhibitors of increasing lipophilicity were synthesized (4, 5, and 6), and their fluorine-18 analogs were evaluated for use as positron emission tomography (PET) imaging agents for prostate cancer. To gain insight into their modes of binding, they were also cocrystallized with the extracellular domain of PSMA. All analogs exhibited irreversible binding to PSMA with IC50 values ranging from 0.4 to 1.3 nM. In vitro assays showed binding and rapid internalization (80-95%, 2 h) of the radiolabeled ligands in PSMA(+) cells. In vivo distribution demonstrated significant uptake in CWR22Rv1 (PSMA(+)) tumor, with tumor to blood ratios of 25.6:1, 63.6:1, and 69.6:1 for [(18)F]4, [(18)F]5, and [(18)F]6, respectively, at 2 h postinjection. Installation of aminohexanoic acid (AH) linkers in the phosphoramidate scaffold improved their PSMA binding and inhibition and was critical for achieving suitable in vivo imaging properties, positioning [(18)F]5 and [(18)F]6 as favorable candidates for future prostate cancer imaging clinical trials.

Dose-Dependent Therapeutic Distinction between Active and Passive Targeting Revealed Using Transferrin-Coated PGMA Nanoparticles

The paradigm of using nanoparticle-based formulations for drug delivery relies on their enhanced passive accumulation in the tumor interstitium. Nanoparticles with active targeting capabilities attempt to further enhance specific delivery of drugs to the tumors via interaction with overexpressed cellular receptors. Consequently, it is widely accepted that drug delivery using actively targeted nanoparticles maximizes the therapeutic benefit and minimizes the off-target effects. However, the process of nanoparticle mediated active targeting initially relies on their passive accumulation in tumors. In this article, it is demonstrated that these two tumor-targeted drug delivery mechanisms are interrelated and dosage dependent. It is reported that at lower doses, actively targeted nanoparticles have distinctly higher efficacy in tumor inhibition than their passively targeted counterparts. However, the enhanced permeability and retention effect of the tumor tissue becomes the dominant factor influencing the efficacy of both passively and actively targeted nanoparticles when they are administered at higher doses. Importantly, it is demonstrated that dosage is a pivotal parameter that needs to be taken into account in the assessment of nanoparticle mediated targeted drug delivery.

Method for Confirming Cytoplasmic Delivery of RNA Aptamers

RNA aptamers are single-stranded RNA oligos that represent a powerful emerging technology with potential for treating numerous diseases. More recently, cell-targeted RNA aptamers have been developed for delivering RNA interference (RNAi) modulators (siRNAs and miRNAs) to specific diseased cells (e.g., cancer cells or HIV infected cells) in vitro and in vivo. However, despite initial promising reports, the broad application of this aptamer delivery technology awaits the development of methods that can verify and confirm delivery of aptamers to the cytoplasm of target cells where the RNAi machinery resides. We recently developed a functional assay (RIP assay) to confirm cellular uptake and subsequent cytoplasmic release of an RNA aptamer which binds to a cell surface receptor expressed on prostate cancer cells (PSMA). To assess cytoplasmic delivery, the aptamer was chemically conjugated to saporin, a ribosome inactivating protein toxin that is toxic to cells only when delivered to the cytoplasm (where it inhibits the ribosome) by a cell-targeting ligand (e.g., aptamer). Here, we describe the chemistry used to conjugate the aptamer to saporin and discuss a gel-based method to verify conjugation efficiency. We also detail an in vitro functional assay to confirm that the aptamer retains function following conjugation to saporin and describe a cellular assay to measure aptamer-mediated saporin-induced cytotoxicity.

Synthesis and biological evaluation of low molecular weight fluorescent imaging agents for the prostate-specific membrane antigen

Targeted near-infrared (NIR) optical imaging can be used in vivo to detect specific tissues, including malignant cells. A series of NIR fluorescent ligands targeting the prostate-specific membrane antigen (PSMA) was synthesized and each compound was tested for its ability to image PSMA+ tissues in experimental models of prostate cancer. The agents were prepared by conjugating commercially available active esters of NIR dyes, including IRDye800CW, IRDye800RS, Cy5.5, Cy7, or a derivative of indocyanine green (ICG) to the terminal amine group of (S)-2-(3-((S)-5-amino-1-carboxypentyl)ureido)pentanedioic acid 1, (14S,18S)-1-amino-8,16-dioxo-3,6-dioxa-9,15,17-triazaicosane-14,18,20-tricarboxylic acid 2 and (3S,7S)-26-amino-5,13,20-trioxo-4,6,12,21-tetraazahexacosane-1,3,7,22-tetracarboxylic acid 3. The K(i) values for the dye-inhibitor conjugates ranged from 1 to 700 pM. All compounds proved capable of imaging PSMA+ tumors selectively to varying degrees depending on the choice of fluorophore and linker. The highest tumor uptake was observed with IRDye800CW employing a poly(ethylene glycol) or lysine-suberate linker, as in 800CW-2 and 800CW-3, while the highest tumor to nontarget tissue ratios were obtained for Cy7 with these same linkers, as in Cy7-2 and Cy7-3. Compounds 2 and 3 provide useful scaffolds for targeting of PSMA+ tissues in vivo and should be useful for preparing NIR dye conjugates designed specifically for clinical intraoperative optical imaging devices.

Experiment specific expression patterns

The differential analysis of genes between microarrays from several experimental conditions or treatments routinely estimates which genes change significantly between groups. As genes are never regulated individually, observed behavior may be a consequence of changes in other genes. Existing approaches like co-expression analysis aim to resolve such patterns from a wide range of experiments. The knowledge of such a background set of experiments can be used to compute expected gene behavior based on known links. It is particularly interesting to detect previously unseen specific effects in other experiments. Here, a new method to spot genes deviating from expected behavior (PAttern DEviation SCOring--Padesco) is devised. It uses linear regression models learned from a background set to arrive at gene specific prediction accuracy distributions. For a given experiment, it is then decided whether each gene is predicted better or worse than expected. This provides a novel way to estimate the experiment specificity of each gene. We propose a validation procedure to estimate the detection of such specific candidates and show that these can be identified with an average accuracy of about 85%.

High-level expression by tissue/cancer-specific promoter with strict specificity using a single-adenoviral vector

Tissue-/cancer-specific promoters for use in adenovirus vectors (AdVs) are valuable for elucidating specific gene functions and for use in gene therapy. However, low activity, non-specific expression and size limitations in the vector are always problems. Here, we developed a 'double-unit' AdV containing the Cre gene under the control of an α-fetoprotein promoter near the right end of its genome and bearing a compact 'excisional-expression' unit consisting of a target cDNA 'upstream' of a potent promoter between two loxPs near the left end of its genome. When Cre was expressed, the expression unit was excised as a circular molecule and strongly expressed. Undesired leak expression of Cre during virus preparation was completely suppressed by a dominant-negative Cre and a short-hairpin RNA against Cre. Using this novel construct, a very strict specificity was maintained while achieving a 40- to 90-fold higher expression level, compared with that attainable using a direct specific promoter. Therefore, the 'double-unit' AdV enabled us to produce a tissue-/cancer-specific promoter in an AdV with a high expression level and strict specificity.

MBP-1 suppresses growth and metastasis of gastric cancer cells through COX-2

The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression but promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth of SC-M1 cells was suppressed by MBP-1 overexpression. Metastasis in lungs of mice was inhibited by MBP-1 after tail vein injection with SC-M1 cells. MBP-1 also suppressed epithelial-mesenchymal transition in SC-M1 cells. Additionally, MBP-1 bound on cyclooxygenase 2 (COX-2) promoter and downregulated COX-2 expression. The MBP-1-suppressed tumor progression in SC-M1 cells were through inhibition of COX-2 expression. MBP-1 also exerted a suppressive effect on tumor progression of other gastric cancer cells such as AGS and NUGC-3 cells. Taken together, these results suggest that MBP-1-suppressed COX-2 expression plays an important role in the inhibition of growth and progression of gastric cancer.

Gamma-tocotrienol suppresses prostate cancer cell proliferation and invasion through multiple-signalling pathways

Tocotrienol-rich fraction (TRF) has demonstrated antiproliferative effect on prostate cancer (PCa) cells. To elucidate this anticancer property in PCa cells, this study aimed, first, to identify the most potent isomer for eliminating PCa cells; and second, to decipher the molecular pathway responsible for its activity. Results showed that the inhibitory effect of γ-tocotrienol was most potent, which resulted in induction of apoptosis as evidenced by activation of pro-caspases and the presence of sub-G₁ cell population. Examination of the pro-survival genes revealed that the γ-tocotrienol-induced cell death was associated with suppression of NF-κB, EGF-R and Id family proteins (Id1 and Id3). Meanwhile, γ-tocotrienol treatment also resulted in the induction of JNK-signalling pathway and inhibition of JNK activity by a specific inhibitor (SP600125) was able to partially block the effect of γ-tocotrienol. Interestingly, γ-tocotrienol treatment led to suppression of mesenchymal markers and the restoration of E-cadherin and γ-catenin expression, which was associated with suppression of cell invasion capability. Furthermore, a synergistic effect was observed when cells were co-treated with γ-tocotrienol and Docetaxel. Our results suggested that the antiproliferative effect of γ-tocotrienol act through multiple-signalling pathways, and demonstrated for the first time the anti-invasion and chemosensitisation effect of γ-tocotrienol against PCa cells.

Comparative proteomics and molecular mechanical analysis in CDA-II induced therapy of LCI-D20 hepatocellular carcinoma model

PURPOSE

To investigate the differential proteins and related molecular mechanism of CDA-II (cell differentiation agent-II) induced therapy on a human hepatocellular carcinoma model in nude mice with high metastatic potential (LCI-D20).

METHODS

After tumors were transplanted 11 days, mice were intraperitoneally injected with CDA-II (1,800 mg/kg) for 20 days continuously. The tumor growth-inhibitory efficiency in CDA-II treated groups was calculated. Proteins extracted from tumor tissue were separated by two-dimensional gel electrophoresis (2DE) and the differential proteins were identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Western blotting (WB) was performed to verify the expression of certain candidate proteins. Reverse transcription-polymerase chain reaction (RT-PCR) was engaged to study the molecular mechanism of the therapy.

RESULTS

CDA-II suppressed the growth and metastasis of tumor. The tumor growth-inhibitory efficiency was 41.8%. In total, 27 differentially expressed proteins were identified, including HSP27, UGDH, CK8, Hsp60, ENOA and AnxA5, with functions involved in oncogene expression and/or cell differentiation. In addition, apparent alternations of HSP60 and beta-actin expression levels and their different posttranslational modifications (PTMs) were investigated. RT-PCR analysis confirmed that the cancer related genes c-myc, N-ras and MMP-9 were significantly down-regulated.

CONCLUSION

Our results demonstrate that CDA-II presence can change the proteome profiling and favors of the tumor suppression in LCI-D20 cell differentiation. Our results also suggest that the dynamic PTM of HSP60 expression levels could be used to predict HCC and might be a promising and useful biomarker to prognosticate CDA-II therapeutic efficacy.

1alpha,25-Dihydroxyvitamin D3 down-regulates expression of prostate specific membrane antigen in prostate cancer cells

BACKGROUND

Prostate specific membrane antigen (PSMA) expression correlates with prostate cancer grade and is increased in hormone-refractory prostate cancer. The increased expression of PSMA following androgen deprivation therapy may be a consequence of the down-regulation of PSMA expression by androgen. Moreover, 1alpha,25-dihydroxyvitamin D3 (1,25-VD) has been shown to suppress prostate cancer progression as well as cell motility and invasion. Since PSMA is positively correlated with both of these characteristics, we hypothesized that 1,25-VD would regulate PSMA expression.

METHODS

LNCaP prostate cancer cells were treated with 1,25-VD, followed by analysis of cell surface PSMA expression. The PSMA enhancer, located within the third intron of the PSMA gene, was cloned into a reporter vector and regulation by 1,25-VD was investigated. The role of the androgen receptor (AR) in 1,25-VD mediated suppression of PSMA expression was examined using Casodex and AR specific siRNA.

RESULTS

Surface expression of PSMA was significantly decreased in a dose-dependent manner by 10 nM 1,25-VD or greater. Regulation by 1,25-VD occurred at the level of the PSMA enhancer. Over-expression of the vitamin D receptor (VDR) also decreased expression of PSMA. Additionally, suppression of AR translation using siRNA technology blocked the suppressive effect of 1,25-VD on PSMA expression, however inhibition of PSMA expression by 1,25-VD occurred in the absence of androgens.

CONCLUSIONS

Suppression of PSMA by 1,25-VD occurs at the level of the PSMA enhancer and is elevated by over-expression of the VDR. This regulation involves the AR, but is not dependent on the presence of androgens.

High expression of PSM-E correlated with tumor grade in prostate cancer: a new alternatively spliced variant of prostate-specific membrane antigen

BACKGROUND

Prostate-specific membrane antigen (PSMA) overexpressed in prostate cancer (PCa) has been targeted for therapy and diagnosis of PCa. In the current study, PSMA cDNA was cloned from PCa tissue by RT-PCR. After sequencing, a new spliced variant of PSMA (PSM-E) was discovered and its specificity in PCa was evaluated.

METHODS

PSM-E and PSMA mRNA were measured in LNCaP, PC-3 and prostate or nonprostatic malignancies. Following transfection of PC-3 with PSM-E cDNA in the pcDNA3.0 vector, PSM-E expression was measured by immunofluorescence and Western-blot. PSM-E and PSMA mRNA levels were quantified by a real-time PCR assay in normal prostate (n = 7), benign prostatic hyperplasia (BPH) (n = 22) and PCa (n = 41). The correlation between their levels and tumor grade was analyzed.

RESULTS

PSM-E cDNA is identical to PSMA except for a 97-nucleotide region and a 93-nucleotide region. PSM-E and PSMA mRNA were detected in PCa and LNCaP, not in PC-3; PSMA could be detected in some nonprostatic tumors whereas PSM-E not. The expression of PSM-E protein was detected in transfected cells. Significant difference of PSM-E mRNA levels was observed among normal prostate, BPH and PCa (P < 0.001), and PSM-E levels increased with increasing Gleason score (r = 0.514, P < 0.001). PSMA mRNA levels were higher in BPH and PCa than in normal prostate (P < 0.001), but no difference between BPH and PCa, no significant correlation was observed between PSMA levels and Gleason score (r = 0.229, P = 0.057).

CONCLUSIONS

PSM-E may be a potential prognostic indicator for PCa progression and may be a new target antigen for therapy of PCa.

A capsid-modified, conditionally replicating oncolytic adenovirus vector expressing TRAIL Leads to enhanced cancer cell killing in human glioblastoma models

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, and patients rarely survive for more than 2 years. Gene therapy may offer new treatment options and improve the prognosis for patients with GBM. Adenovirus-mediated gene therapy strategies for brain tumors have been limited by inefficient gene transfer due to low expression of the adenovirus serotype 5 (Ad5) receptor. We have used an adenovirus vector that specifically replicates in tumor cells and uses an Ad5 capsid and the adenovirus serotype (Ad35) fiber for efficient infection of malignant tumor cells. This vector also expresses adenovirus E1A and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a tumor-specific manner. Here, we show that this oncolytic vector (Ad5/Ad35.IR-E1A/TRAIL) efficiently infects the GBM tumor cell lines SF767, T98G, and U-87 MG. Tumor cell killing was markedly enhanced with Ad5/Ad35.IR-E1A/TRAIL compared with wild-type Ad5 and Ad35 virus or Ad5/Ad35.IR-E1A- vectors without TRAIL expression in vitro. In vivo experiments using s.c. xenografted U-87 MG cells in NOD/SCID mice showed a significant growth delay of tumors after i.t. injection of Ad5/Ad35.IR-E1A/TRAIL, whereas adenovirus wild-type injections showed only marginal or no effect. Our findings indicate that the use of a capsid-modified adenoviral vector, in combination with TRAIL expression, is a promising novel approach for gene therapy of glioblastoma.

Emerging roles of proteases in tumour suppression

Proteases have long been associated with cancer progression because of their ability to degrade extracellular matrices, which facilitates invasion and metastasis. However, recent studies have shown that these enzymes target a diversity of substrates and favour all steps of tumour evolution. Unexpectedly, the post-trial studies have also revealed proteases with tumour-suppressive effects. These effects are associated with more than 30 different enzymes that belong to three distinct protease classes. What are the clinical implications of these findings?

A 90 kDa fragment of filamin A promotes Casodex-induced growth inhibition in Casodex-resistant androgen receptor positive C4-2 prostate cancer cells

Prostate tumors are initially dependent on androgens for growth, but the majority of patients treated with anti-androgen therapy progress to androgen-independence characterized by resistance to such treatment. This study investigates a novel role for filamin A (FlnA), a 280 kDa cytoskeletal protein (consisting of an actin-binding domain (ABD) followed by 24 sequential repeats), in androgen-independent (AI) growth. Full-length FlnA is cleaved to 170 kDa (ABD+FlnA1-15) and 110 kDa fragments (FlnA16-24); the latter is further cleaved to a 90 kDa fragment (repeats 16-23) capable of nuclear translocation and androgen receptor (AR) binding. Here, we demonstrate that in androgen-dependent LNCaP prostate cancer cells, the cleaved 90 kDa fragment is localized to the nucleus, whereas in its AI subline C4-2, FlnA failed to cleave and remained cytoplasmic. Transfection of FlnA16-24 cDNA in C4-2 cells restored expression and nuclear localization of 90 kDa FlnA. Unlike LNCaP, C4-2 cells proliferate in androgen-reduced medium and in the presence of the AR-antagonist Casodex. They also exhibit increased Akt phosphorylation compared to LNCaP, which may contribute to their AI phenotype. Nuclear expression of 90 kDa FlnA in C4-2 cells decreased Akt phosphorylation, prevented proliferation in androgen-reduced medium and restored Casodex sensitivity. This effect was inhibited by constitutive activation of Akt indicating that FlnA restored Casodex sensitivity in C4-2 cells by decreasing Akt phosphorylation. In addition, FlnA-specific siRNA which depleted FlnA levels, but not control siRNA, induced resistance to Casodex in LNCaP cells. Our results demonstrate that expression of nuclear FlnA is necessary for androgen dependence in these cells.

Analysis of prostate-specific membrane antigen splice variants in LNCap cells

The prostate-specific membrane antigen (PSMA), a product of the folate hydrolase (FOLH1) gene, is highly expressed as a largely extracellular membrane-anchored protein in malignant prostate tissues and in nonprostatic tumor neovasculature. Treatment of prostate cancer LNCap cells with spliceswitching oligonucleotides (SSOs) modulated splicing of FOLH1 pre-mRNA from the full-length PSMA splice variant to three splice variants: the cytoplasmic PSM', alternatively spliced at exon 1, and the previously unexamined PSMADelta6 and PSMADelta18 variants, which lack exons 6 and 18, respectively. Application of SSOs decreased membrane PSMA levels and increased PSM', PSMADelta6, and PSMADelta18 transcripts. As a result, PSM' protein was translocated to the cytoplasm, and switching to PSMADelta6 and PSMADelta18 downregulated PSMA expression. NAALADase assays showed that PSM' retained enzymatic activity. PSMADelta6 and PSMADelta18 were not active, presumably due to a change in a reading frame that eliminated the NAALDase active site or the dimerization domain or both in these proteins.

Cationic antimicrobial peptides as novel cytotoxic agents for cancer treatment

Cancer treatment by conventional chemotherapy is hindered by toxic side effects and the frequent development of multi-drug resistance by cancer cells. Cationic antimicrobial peptides (CAPs) are a promising new class of natural-source drugs that may avoid the shortcomings of conventional chemotherapy because certain CAPs exhibit selective cytotoxicity against a broad spectrum of human cancer cells, including neoplastic cells that have acquired a multi-drug-resistant phenotype. Tumour cell killing by CAPs is usually by a cell membrane-lytic effect, although some CAPs can trigger apoptosis in cancer cells via mitochondrial membrane disruption. Furthermore, certain CAPs are potent inhibitors of blood vessel development (angiogenesis) that is associated with tumour progression. This article reviews the mechanisms by which CAPs exert anticancer activity and discusses the potential application of selected CAPs as therapeutic agents for the treatment of human cancers.

Knockdown of MBP-1 in human prostate cancer cells delays cell cycle progression

We have previously shown that MBP-1 acts as a general transcriptional repressor, and forced expression of MBP-1 exerts an anti-proliferative effect on a number of human cancer cells. In this report, we have investigated the role of endogenous MBP-1 in cell growth regulation. For this, we generated human prostate cancer cells (PC3) stably transfected with short hairpin RNA targeting MBP-1. We have observed retarded growth and longer doubling time of MBP-1 knockdown PC3 cells as compared with control mock-transfected PC3 cells. Fluorescence-activated cell sorter analysis suggested that PC3 cells expressing MBP-1-specific small interfering RNA accumulated during G2/M phase of the cell cycle. Further analysis suggested that depletion of MBP-1 was associated with reduction of cyclin A and cyclin B1 expression when compared with that of the control cells. A delayed induction of cyclin A and B1 expression was observed in MBP-1-depleted PC3 cells (PC3-4.2) upon serum stimulation, although the level of expression was much lower than that of control PC3 cells. Supplementation of MBP-1 in PC3-4.2 cells restored cyclin A and cyclin B1 expression. Together, these results suggest that knockdown of MBP-1 in prostate cancer cells perturbs cell proliferation by inhibiting cyclin A and cyclin B1 expression.

Use of replication-competent retroviral vectors in an immunocompetent intracranial glioma model

OBJECT

The authors had previously reported on a replication-competent retrovirus (RCR) that has been demonstrated to be stable, capable of effective transduction, and able to prolong survival in an intracranial tumor model in nude mice. The purpose of this study was further investigation of this gene therapy option.

METHODS

The transduction efficiency of RCR in RG2, an immunocompetent intracranial tumor model, was tested in Fischer 344 rats. The immune response to the RCR vector was expressed by the quantification of CD4, CD8, and CD11/b in tumors. The pharmaceutical efficacy of the suicide gene CD in converting prodrug 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) was measured using fluorine-19 nuclear magnetic resonance (19F-NMR) spectroscopy. Animal survival data were plotted on Kaplan-Meier survival curves. Finally, the biodistribution of RCR was determined using quantitative real-time polymerase chain reaction (RT-PCR) for the detection of retroviral env gene. There was no evidence of viral transduction in normal brain cells. Neither severe inflammation nor immunoreaction occurred after intracranial injection of RCR-green fluorescent protein compared with phosphate-buffered saline (PBS). The 19F-NMR spectroscopy studies demonstrated that RCR-CD was able to convert 5-FC to 5-FU effectively in vitro. The infection of RG2 brain tumors with RCR-CD and their subsequent treatment with 5-FC significantly prolonged survival compared with that in animals with RG2 transduced tumors treated with PBS. In contrast to the nude mouse model, evidence of virus dissemination to the systemic organs after intracranial injection was not detected using RT-PCR.

CONCLUSIONS

The RCR-mediated suicide gene therapy described in this paper effectively transduced malignant gliomas in an immunocompetent in vivo rodent model, prolonging survival, without evidence of severe intracranial inflammation, and without local transduction of normal brain cells or systemic organs.

Introduction of in vitro transcribed ENO1 mRNA into neuroblastoma cells induces cell death

Background

Neuroblastoma is a solid tumour of childhood often with an unfavourable outcome. One common genetic feature in aggressive tumours is 1p-deletion.

The α-enolase (ENO1) gene is located in chromosome region 1p36.2, within the common region of deletion in neuroblastoma. One alternative translated product of the ENO1 gene, known as MBP-1, acts as a negative regulator of the c-myc oncogene, making the ENO1 gene a candidate as a tumour suppressor gene.

Methods

Methods used in this study are transfection of cDNA-vectors and in vitro transcribed mRNA, cell growth assay, TUNEL-assay, real-time RT-PCR (TaqMan) for expression studies, genomic sequencing and DHPLC for mutation detection.

Results

Here we demonstrate that transfection of ENO1 cDNA into 1p-deleted neuroblastoma cell lines causes' reduced number of viable cells over time compared to a negative control and that it induces apoptosis. Interestingly, a similar but much stronger dose-dependent reduction of cell growth was observed by transfection of in vitro transcribed ENO1 mRNA into neuroblastoma cells. These effects could also be shown in non-neuroblastoma cells (293-cells), indicating ENO1 to have general tumour suppressor activity.

Expression of ENO1 is detectable in primary neuroblastomas of all different stages and no difference in the level of expression can be detected between 1p-deleted and 1p-intact tumour samples. Although small numbers (11 primary neuroblastomas), there is some evidence that Stage 4 tumours has a lower level of ENO1-mRNA than Stage 2 tumours (p = 0.01). However, mutation screening of 44 primary neuroblastomas of all different stages, failed to detect any mutations.

Conclusion

Our studies indicate that ENO1 has tumour suppressor activity and that high level of ENO1 expression has growth inhibitory effects.

c-myc Promoter-binding protein 1 (MBP-1) regulates prostate cancer cell growth by inhibiting MAPK pathway

Prostate cancer is the most common and invasive type of cancer among American men, and the second leading cause of cancer-elated deaths in the United States. Unfortunately, an effective therapeutic regimen is still lacking for advance stages of the disease. Recently, MEK5 has been shown to overexpress in prostate cancer and is associated with poor survival outcome. MEK5 exists as alpha- and beta-isoforms. MEK5alpha induces cell proliferation by activating its downstream molecules, whereas MEK5beta expression is associated with inhibition of cell growth. We have recently shown that exogenous expression of c-myc promoter-binding protein 1 (MBP-1) induces prostate cancer cell death (Ghosh, A. K., Steele, R., and Ray, R. B. (2005) Cancer Res. 65, 718-721). In this study, we have investigated whether inhibition of MEK5 signaling pathway can modulate prostate cancer cell growth. MBP-1 is a general transcriptional repressor and modulates a number of cellular genes. Therefore, we examined the endogenous expression status of MEK5 in androgen-independent prostate cancer cells upon recombinant adenovirus-mediated introduction of MBP-1. Our results demonstrated that MBP-1 expression reduced the endogenous MEK5alpha protein level; on the other hand, MEK5beta expression was enhanced significantly. Transduction of MBP-1 modulates the downstream signaling molecules of MEK5, such as activation of the cyclin D1 promoter and MEF2C transcriptional activities in androgen-independent prostate cancer cells. MBP-1 expression also modulates MEK5-mediated activation of NF-kappaB. Further analysis suggested that MBP-1 physically associates with MEK5 and induces proteasome-mediated degradation of the MEK5 protein, which appears to occur independently of ubiquitination. Together, our results suggested a novel role of MBP-1 for suppression of prostate cancer cell growth by regulating the MEK5-mediated signaling pathway.