A novel regulation of PSMA and PSA expression by Q640X AR in 22Rv1 and LNCaP prostate cancer cells

Pentamethine cyanine dyes with alkynyl group as perspective structure for conjugation with targeting moiety

We report a modified carbocyanine-based asymmetric fluorescent dye, suitable for the azide-alkyne cycloaddition reaction, that possesses promising photochemical properties (Φfl = 0,49). As an example of usage of the new fluorophore, it was conjugated to a ligand targeting prostate-specific membrane antigen (PSMA), one of the widely utilized prostate cancer markers.

Development of [177Lu]Lu-LNC1003 for radioligand therapy of prostate cancer with a moderate level of PSMA expression

PURPOSE

Evans blue as an albumin binder has been widely used to improve pharmacokinetics and enhance tumor uptake of radioligands, including prostate-specific membrane antigen (PSMA) targeting agents. The goal of this study is to develop an optimal Evans blue-modified radiotherapeutic agent that could maximize the absolute tumor uptake and tumor absorbed dose thus the therapeutic efficacy to allow treatment of tumors even with moderate level of PSMA expression.

METHODS

[177Lu]Lu-LNC1003 was synthesized based on PSMA-targeting agent and Evans blue. Binding affinity and PSMA targeting specificity were verified through cell uptake and competition binding assay in 22Rv1 tumor model that has moderate level of PSMA expression. SPECT/CT imaging and biodistribution studies in 22Rv1 tumor-bearing mice were performed to evaluate the preclinical pharmacokinetics. Radioligand therapy studies were conducted to systematically assess the therapeutic effect of [177Lu]Lu-LNC1003.

RESULTS

LNC1003 showed high binding affinity (IC50 = 10.77 nM) to PSMA in vitro, which was comparable with that of PSMA-617 (IC50 = 27.49 nM) and EB-PSMA-617 (IC50 = 7.91 nM). SPECT imaging of [177Lu]Lu-LNC1003 demonstrated significantly improved tumor uptake and retention as compared with [177Lu]Lu-EB-PSMA and [177Lu]Lu-PSMA-617, making it suitable for prostate cancer therapy. Biodistribution studies further confirmed the remarkably higher tumor uptake of [177Lu]Lu-LNC1003 (138.87 ± 26.53%ID/g) over [177Lu]Lu-EB-PSMA-617 (29.89 ± 8.86%ID/g) and [177Lu]Lu-PSMA-617 (4.28 ± 0.25%ID/g) at 24 h post-injection. Targeted radioligand therapy results showed noteworthy inhibition of 22Rv1 tumor growth after administration of a single dose of 18.5 MBq [177Lu]Lu-LNC1003. There was no obvious antitumor effect after [177Lu]Lu-PSMA-617 treatment under the same condition.

CONCLUSION

In this study, [177Lu]Lu-LNC1003 was successfully synthesized with high radiochemical purity and stability. High binding affinity and PSMA targeting specificity were identified in vitro and in vivo. With greatly enhanced tumor uptake and retention, [177Lu]Lu-LNC1003 has the potential to improve therapeutic efficacy using significantly lower dosages and less cycles of 177Lu that promises clinical translation to treat prostate cancer with various levels of PSMA expression.

Nanoparticles Targeted to Fibroblast Activation Protein Outperform PSMA for MRI Delineation of Primary Prostate Tumors

Accurate delineation of gross tumor volumes remains a barrier to radiotherapy dose escalation and boost dosing in the treatment of solid tumors, such as prostate cancer. Magnetic resonance imaging (MRI) of tumor targets has the power to enable focal dose boosting, particularly when combined with technological advances such as MRI-linear accelerator. Fibroblast activation protein (FAP) is overexpressed in stromal components of >90% of epithelial carcinomas. Herein, the authors compare targeted MRI of prostate specific membrane antigen (PSMA) with FAP in the delineation of orthotopic prostate tumors. Control, FAP, and PSMA-targeting iron oxide nanoparticles were prepared with modification of a lymphotropic MRI agent (FerroTrace, Ferronova). Mice with orthotopic LNCaP tumors underwent MRI 24 h after intravenous injection of nanoparticles. FAP and PSMA nanoparticles produced contrast enhancement on MRI when compared to control nanoparticles. FAP-targeted MRI increased the proportion of tumor contrast-enhancing black pixels by 13%, compared to PSMA. Analysis of changes in R2 values between healthy prostates and LNCaP tumors indicated an increase in contrast-enhancing pixels in the tumor border of 15% when targeting FAP, compared to PSMA. This study demonstrates the preclinical feasibility of PSMA and FAP-targeted MRI which can enable targeted image-guided focal therapy of localized prostate cancer.

Establishment of an orthotopic prostate cancer xenograft mouse model using microscope-guided orthotopic injection of LNCaP cells into the dorsal lobe of the mouse prostate

Background

Orthotopic LNCaP xenograft mouse models closely mimic the progression of androgen-dependent prostate cancer in humans; however, orthotopic injection of LNCaP cells into the mouse prostate remains a challenge.

Methods

Under the guidance of a stereoscopic microscope, the anatomy of the individual prostate lobes in male Balb/c athymic nude mice was investigated, and LNCaP cells were inoculated into the mouse dorsal prostate (DP) to generate orthotopic tumors that mimicked the pathophysiological process of prostate cancer in humans. Real-time ultrasound imaging was used to monitor orthotopic prostate tumorigenesis, contrast-enhanced ultrasonography (CEUS) was used to characterize tumor angiogenesis, and macroscopic and microscopic characteristics of tumors were described.

Results

The DP had a trigonal bipyramid-shape and were located at the base of the seminal vesicles. After orthotopic inoculation, gray scale ultrasound imaging showed progressive changes in tumor echotexture, shape and location, and tumors tended to protrude into the bladder. After 8 weeks, the tumor take rate was 65% (n = 13/20 mice). On CEUS, signal intensity increased rapidly, peaked, and decreased gradually. Observations of gross specimens showed orthotopic prostate tumors were well circumscribed, round, dark brown, and soft, with a smooth outer surface and a glossy appearance. Microscopically, tumor cells were arranged in acini encircled by fibrous septa with variably thickened walls, mimicking human adenocarcinoma.

Conclusions

This study describes a successful approach to establishing an orthotopic LNCaP xenograft Balb/c athymic nude mouse model. The model requires a thorough understanding of mouse prostate anatomy and proper technique. The model represents a valuable tool for the in vivo study of the biological processes involved in angiogenesis in prostate cancer and preclinical evaluations of novel anti-angiogenic therapies.

Roles of Progesterone, Testosterone and Their Nuclear Receptors in Central Nervous System Myelination and Remyelination

Progesterone and testosterone, beyond their roles as sex hormones, are neuroactive steroids, playing crucial regulatory functions within the nervous system. Among these, neuroprotection and myelin regeneration are important ones. The present review aims to discuss the stimulatory effects of progesterone and testosterone on the process of myelination and remyelination. These effects have been demonstrated in vitro (i.e., organotypic cultures) and in vivo (cuprizone- or lysolecithin-induced demyelination and experimental autoimmune encephalomyelitis (EAE)). Both steroids stimulate myelin formation and regeneration by acting through their respective intracellular receptors: progesterone receptors (PR) and androgen receptors (AR). Activation of these receptors results in multiple events involving direct transcription and translation, regulating general homeostasis, cell proliferation, differentiation, growth and myelination. It also ameliorates immune response as seen in the EAE model, resulting in a significant decrease in inflammation leading to a fast recovery. Although natural progesterone and testosterone have a therapeutic potential, their synthetic derivatives—the 19-norprogesterone (nestorone) and 7α-methyl-nortestosterone (MENT), already used as hormonal contraception or in postmenopausal hormone replacement therapies, may offer enhanced benefits for myelin repair. We summarize here a recent advancement in the field of myelin biology, to treat demyelinating disorders using the natural as well as synthetic analogs of progesterone and testosterone.

PSMA Antibody-Conjugated Pentablock Copolymer Nanomicellar Formulation for Targeted Delivery to Prostate Cancer

The main purpose of this study was to develop a prostate-specific membrane antigen (PSMA) antibody-conjugated drug-loaded nanomicelles using MPEG--PLA-PCL-PLA-PEG-NH2 pentablock copolymer for targeted delivery of hydrophobic anticancer drugs to prostate cancer cells. During this experiment, monomers of L-lactide, ε-caprolactone, poly(ethylene glycol)-methyl ether, and poly(ethylene glycol)-NH2 were used to prepare pentablock copolymer using the ring opening technique. The pentablock nanomicellar (PBNM) formulation was prepared by the evaporation-rehydration method. The resultant pentablock nanomicelles were then conjugated with PSMA antibody resulting in PSMA-Ab-PTX-PBNM. Both the block copolymers and the nanomicelles were analyzed by hydrogen nuclear magnetic resonance (H-NMR), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The obtained nanomicelles (NM) were then analyzed for size and zeta potential using dynamic light scattering-dynamic laser scattering (DLS) and then further submitted to H-NMR and TEM analyses. The XRD, FTIR, and the H-NMR analyses confirmed the structure of the pentablock copolymers. The average size for conjugated nanomicellar was 45 nm ± 2.5 nm. The average (ζ-potential) was around - 28 mV. H-NMR and FTIR analysis done on PSMA-coupled paclitaxel-loaded PBNM showed peaks characteristic of the drug (paclitaxel) and the polymer, confirming the successful encapsulation. TEM analysis showed well-defined spherical morphology and confirmed the size range obtained by the DLS. In vitro release studies revealed sustained slow of PTX in phosphate buffer solution (PBS). Confocal scanning microscopy (TEM) of coumarin6-loaded in PBNM indicated that pentablock nanomicelles were internalized into the prostate cancer (PC-3) cells. Cell proliferation assay showed that nanomicelles ferried paclitaxel into the PC-3 cells and subsequently reduced the cell proliferation. The results depict PTX-PBNM-Ab as a suitable carrier for targeted delivery of drugs to prostate cancer cells.