Research in castration-resistant prostate cancer: what does the future hold?

Reactivation of nucleases with peroxidation damages induced by a menadione: ascorbate combination devastates human prostate carcinomas: ultrastructural aspects

INTRODUCTION

Xenografts of androgen-independent human DU145 prostate metastatic carcinomas implanted in nu/nu male mice have revealed a significant survival after a prooxidant anticancer treatment consisting of a combination of menadione bisulfite and sodium ascorbate (VK3:VC).

METHODS

Implanted samples of diaphragm carcinomas from longest survived mice from either oral, intraperitoneal (IP), or both oral and IP treatment groups were assessed with light, scanning, and transmission electron microscopy to analyze morphologic damages.

RESULTS

Compared with previous fine structure data of in vitro untreated carcinomas, the changes induced by oral, IP, and oral with IP VK3:VC treatment dismantled those xenografts with autoschizis, and necrotic atrophy was accomplished by cell's oxidative stress whose injuries were consequent to reactivated deoxyribonucleases and ribonucleases. Tumor destructions resulted from irreversible damages of nucleus components, endoplasmic reticulum, and mitochondria there. Other alterations included those of the cytoskeleton that resulted in characteristic self-excisions named " autoschizis." All these injuries lead resilient cancer cells to necrotic cell death.

CONCLUSION

The fine structure damages caused by VK3:VC prooxidant combination in the human DU145 prostate xenografts confirmed those shown in vitro and of other cell lines with histochemistry and biomolecular investigations. These devastations incurred without damage to normal tissues; thus, our data brought support for the above combination to assist in the treatment of prostate cancers and other cancers.

Xenografts on nude mouse diaphragm of human DU145 prostate carcinoma cells: mesothelium removal by outgrowths and angiogenesis

Human prostate carcinoma DU145 cells, androgen-independent malignant cells, implanted in the athymic nu/nu male mouse, developed numerous tumors on peritoneal and retro-peritoneal organs whose growth aspects and vascular supply have yet to be investigated with fine structure techniques. A series of necropsies from moribund implanted mice diaphragms were examined with light, scanning, and transmission electron microscopy. DU145 xenografts installations, far away from the implanted site, were described as the smallest installation to large diaphragm outgrowths in moribund mice. Carcinomas did not show extracellular matrix and, reaching more than 0.15 mm in thickness, they revealed new structures in these outgrowths. Voids to be gland-like structures with mediocre secretion and, unexpectedly, intercellular spaces connected with fascicles of elongated DU145 cells that merged with a vascular supply originated from either the tumor cells and/or some perimysium vessels. In the largest carcinomas, most important vascular invasions coincidently accompanied the mouse lethality, similarly to human cancers. This androgen-independent model would be useful to study tumor outgrowth's changes related to testing anticancer strategy, including anti-angiogenic therapies involving toxicity, simultaneously with those of other vital organs with combined biomolecular and fine structure techniques.

Structure–activity relationship analysis of a series of nonsteroidal analogues as androgen receptor antagonists

Computer-aided drug design technology was used to screen drugs in large-scale and to accelerate the progress of drug design of nonsteroidal compounds deriving from the hybridization of FDA-approved Enzalutamide and Abiraterone.

Suppression of Prostate Cancer Pathogenesis Using an MDA-9/Syntenin (SDCBP) PDZ1 Small-Molecule Inhibitor

Metastasis is the primary determinant of death in patients with diverse solid tumors and MDA-9/Syntenin (SDCBP), a pro-metastatic and pro-angiogenic gene, contributes to this process. Recently, we documented that by physically interacting with IGF-1R, MDA-9/Syntenin activates STAT3 and regulates prostate cancer pathogenesis. These observations firmly established MDA-9/Syntenin as a potential molecular target in prostate cancer. MDA-9/Syntenin contains two highly homologous PDZ domains predicted to interact with a plethora of proteins, many of which are central to the cancerous process. An MDA-9/Syntenin PDZ1 domain-targeted small molecule (PDZ1i) was previously developed using fragment-based drug discovery (FBDD) guided by NMR spectroscopy and was found to be well-tolerated in vivo, had significant half-life (t _1/2 = 9 hours) and displayed substantial anti-prostate cancer preclinical in vivo activity. PDZ1i blocked tumor cell invasion and migration in vitro, and metastasis in vivo Hence, we demonstrate that PDZ1i an MDA-9/Syntenin PDZ1 target-specific small-molecule inhibitor displays therapeutic potential for prostate and potentially other cancers expressing elevated levels of MDA-9/Syntenin.

Role of exosomal small RNA in prostate cancer metastasis

Prostate cancer (PCa) is the second most common cancer in men worldwide. When the disease becomes metastatic, limited treatment strategies exist, and metastatic disease prognoses are difficult to predict. Recently, evidence has emerged, which indicates that small RNAs are detectable in patient fluids, and exosomal small RNA ectopic expression is correlated with the development, progression, and metastasis of human PCa; however, the role of small RNAs in PCa is only partially understood. In this review, we discuss the research status regarding circulating exosomal small RNAs and applications using these small RNAs in PCa particularly looking at metastatic disease. Exosomal small RNAs could be used as potential biomarkers for the early diagnosis, micrometastasis detection, and prognosis of PCa.

Androgen receptor: structure, role in prostate cancer and drug discovery

Androgens and androgen receptors (AR) play a pivotal role in expression of the male phenotype. Several diseases, such as androgen insensitivity syndrome (AIS) and prostate cancer, are associated with alterations in AR functions. Indeed, androgen blockade by drugs that prevent the production of androgens and/or block the action of the AR inhibits prostate cancer growth. However, resistance to these drugs often occurs after 2–3 years as the patients develop castration-resistant prostate cancer (CRPC). In CRPC, a functional AR remains a key regulator. Early studies focused on the functional domains of the AR and its crucial role in the pathology. The elucidation of the structures of the AR DNA binding domain (DBD) and ligand binding domain (LBD) provides a new framework for understanding the functions of this receptor and leads to the development of rational drug design for the treatment of prostate cancer. An overview of androgen receptor structure and activity, its actions in prostate cancer, and how structural information and high-throughput screening have been or can be used for drug discovery are provided herein.

Androgen deprivation-induced NCoA2 promotes metastatic and castration-resistant prostate cancer

A major clinical hurdle for the management of advanced prostate cancer (PCa) in patients is the resistance of tumors to androgen deprivation therapy (ADT) and their subsequent development into castration-resistant prostate cancer (CRPC). While recent studies have identified potential pathways involved in CRPC development, the drivers of CRPC remain largely undefined. Here we determined that nuclear receptor coactivator 2 (NCoA2, also known as SRC-2), which is frequently amplified or overexpressed in patients with metastatic PCa, mediates development of CRPC. In a murine model, overexpression of NCoA2 in the prostate epithelium resulted in neoplasia and, in combination with Pten deletion, promoted the development of metastasis-prone cancer. Moreover, depletion of NCoA2 in PTEN-deficient mice prevented the development of CRPC. In human androgen-sensitive prostate cancer cells, androgen signaling suppressed NCoA2 expression, and NCoA2 overexpression in murine prostate tumors resulted in hyperactivation of PI3K/AKT and MAPK signaling, promoting tumor malignance. Analysis of PCa patient samples revealed a strong correlation among NCoA2-mediated signaling, disease progression, and PCa recurrence. Taken together, our findings indicate that androgen deprivation induces NCoA2, which in turn mediates activation of PI3K signaling and promotes PCa metastasis and CRPC development. Moreover, these results suggest that the inhibition of NCoA2 has potential for PCa therapy.

Angiotensin-(1-7) attenuates metastatic prostate cancer and reduces osteoclastogenesis

BACKGROUND

Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, heptapeptide hormone with anti-proliferative and anti-angiogenic properties. The primary objective of this study was to determine whether Ang-(1-7) effectively reduces prostate cancer metastasis in mice.

METHODS

Human PC3 prostate cancer cells were injected into the aortic arch via the carotid artery of SCID mice pre-treated with Ang-(1-7) or injected into the tibia of athymic mice, administered Ang-(1-7) for 5 weeks beginning 2 weeks post-injection. Tumor growth and volume were determined by bioluminescent and magnetic resonance imaging. The presence of tumors was confirmed by hematoxylin and eosin staining; TRAP histochemistry was used to identify osteolytic lesions. The effect of Ang-(1-7) on osteoclastogenesis was assessed in differentiated bone marrow cells.

RESULTS

Pre-treatment with Ang-(1-7) prevented metastatic tumor formation following intra-aortic injection of PC3 cells, while 83% of untreated mice developed tumors in metastatic sites. Circulating VEGF was significantly higher in control mice compared to mice administered Ang-(1-7). A 5-week regimen of the heptapeptide hormone attenuated intra-tibial tumor growth; Ang-(1-7) was significantly higher in the tibia of treated mice than in control animals. Osteoclastogenesis was reduced by 50% in bone marrow cells differentiated in the presence of Ang-(1-7), suggesting that the heptapeptide hormone prevents the formation of osteolytic lesions to reduce tumor survival in the bone microenvironment.

CONCLUSIONS

These findings suggest that Ang-(1-7) may serve as an anti-angiogenic and anti-metastatic agent for advanced prostate cancer. By extension, the heptapeptide hormone may provide effective therapy for bone metastasis produced from primary tumors of the lung and breast.

NGF/γ-IFN inhibits androgen-independent prostate cancer and reverses androgen receptor function through downregulation of FGFR2 and decrease in cancer stem cells

Androgen-independent prostate cancer (AIPC) is difficult to treat. Present study is to explore the inhibitory effect of a cytokine environment on AIPC and its mechanism. We utilized nerve growth factor (NGF)/γ-interferon (γ-IFN) to change the cytokine environment. Animal models and 2 androgen receptor (AR)-negative prostate cancer cell lines were used to evaluate the effect of NGF/γ-IFN. Flow cytometry, immunocytochemistry, western blotting, Tunel assay, colony formation efficiency, gene microarray, and in vivo bioluminescence were used to discern the mechanisms within NGF/γ-IFN that effect the environment. In vitro, NGF/γ-IFN effectively inhibited the proliferation of AIPC cell lines and promoted the apoptosis of the cancer cells. In vivo, NGF/γ-IFN suppressed the growth and metastasis of a tumor mass that arose from the AIPC cell line. After NGF/γ-IFN treatment, the AR-negative cell lines re-expressed AR and were then able to respond to the androgen. Contrary to expectations, the proliferation of cells was inhibited after dihydrotestosterone was added, and the results indicated that NGF/γ-IFN decreased the proportion of cancer stem cells. NGF/γ-IFN worked mainly through the downregulation of fibroblast growth factor receptor 2.