Pseurotin A Validation as a Metastatic Castration-Resistant Prostate Cancer Recurrence-Suppressing Lead via PCSK9-LDLR Axis Modulation.

Metastatic castration-resistant prostate cancer (mCRPC) cells can de novo biosynthesize their own cholesterol and overexpress proprotein convertase subtilisin/kexin type 9 (PCSK9). PCSK9 proved to contribute to mCRPC cell motility since PCSK9 knockdown (KD) in mCRPC CWR-R1ca cells led to notable reductions in cell migration and colony formation. Human tissue microarray results proved a higher immunohistoscore in patients ≥ 65 years old, and PCSK9 proved to be expressed higher at an early Gleason score of ≤7. The fermentation product pseurotin A (PS) suppressed PCSK9 expression, protein-protein interactions with LDLR, and breast and prostate cancer recurrences. PS suppressed migration and colony formation of the CWR-R1ca cells. The progression and metastasis of the CWR-R1ca-Luc cells subcutaneously (sc) xenografted into male nude mice fed a high-fat diet (HFD, 11% fat content) showed nearly 2-fold tumor volume, metastasis, serum cholesterol, low-density lipoprotein cholesterol (LDL-C), prostate-specific antigen (PSA), and PCSK9 levels versus mice fed a regular chow diet. Daily oral PS 10 mg/kg treatments prevented the locoregional and distant tumor recurrence of CWR-R1ca-Luc engrafted into nude mice after primary tumor surgical excision. PS-treated mice showed a significant reduction in serum cholesterol, LDL-C, PCSK9, and PSA levels. These results comprehensively validate PS as an mCRPC recurrence-suppressive lead by modulating the PCSK9-LDLR axis.

Towards Developing Novel Prostate Cancer Recurrence Suppressors: Acute Toxicity of Pseurotin A, an Orally Active PCSK9 Axis-Targeting Small-Molecule in Swiss Albino Mice.

The proprotein convertase subtilisin kexin type 9 (PCSK9) emerged as a molecular target of great interest for the management of cardiovascular disorders due to its ability to reduce low density lipoprotein (LDL) cholesterol by binding and targeting at LDLR for lysosomal degradation in cells. Preliminary studies revealed that pseurotin A (PsA), a spiro-heterocyclic γ-lactam alkaloid from several marine and terrestrial Aspergillus and Penicillium species, has the ability to dually suppress the PCSK9 expression and protein-protein interaction (PPI) with LDLR, resulting in an anti-hypercholesterolemic effect and modulating the oncogenic role of PCSK9 axis in breast and prostate cancers progression and recurrence. Thus, a preliminary assessment of the PsA acute toxicity represents the steppingstone to develop PsA as a novel orally active PCSK9 axis modulating cancer recurrence inhibitor. PsA studies for in vitro toxicity on RWPE-1 and CCD 841 CoN human non-tumorigenic prostate and colon cells, respectively, indicated a cellular death shown at a 10-fold level of its reported anticancer activity. Moreover, a Western blot analysis revealed a significant downregulation of the pro-survival marker Bcl-2, along with the upregulation of the proapoptotic Bax and caspases 3/7, suggesting PsA-mediated induction of cell apoptosis at very high concentrations. The Up-and-Down methodology determined the PsA LD50 value of >550 mg/kg in male and female Swiss albino mice. Animals were orally administered single doses of PsA at 10, 250, and 500 mg/kg by oral gavage versus vehicle control. Mice were observed daily for 14 days with special care over the first 24 h after dosing to monitor any abnormalities in their behavioral, neuromuscular, and autonomic responses. After 14 days, the mice were euthanized, and their body and organ weights were recorded and collected. Mice plasma samples were subjected to comprehensive hematological and biochemical analyses. Collected mouse organs were histopathologically examined. No morbidity was detected following the PsA oral dosing. The 500 mg/kg female dosing group showed a 45% decrease in the body weight after 14 days but displayed no other signs of toxicity. The 250 mg/kg female dosing group had significantly increased serum levels of liver transaminases AST and ALT versus vehicle control. Moreover, a modest upregulation of apoptotic markers was observed in liver tissues of both animal sexes at 500 mg/kg dose level. However, a histopathological examination revealed no damage to the liver, kidneys, heart, brain, or lungs. While these findings suggest a possible sex-related toxicity at higher doses, the lack of histopathological injury implies that single oral doses of PsA, up to 50-fold the therapeutic dose, do not cause acute organ toxicity in mice though further studies are warranted.

Ion transport mechanism in anhydrous lithium thiocyanate LiSCN part II: frequency dependence and slow jump relaxation.

Specific aspects of the Li+ cation conductivity of anhydrous Li(SCN) are investigated, in particular the high migration enthalpy of lithium vacancies. Close inspection of impedance spectra and conductivity data reveals two bulk relaxation processes, with comparatively fast ion transport at high frequencies and slow ion migration at low frequencies. The impedance results are supported by solid state nuclear magnetic resonance (ssNMR), and pair distribution function (PDF) analysis. This behavior reflects a frequency dependent conductivity, which is related to the extremely slow thiocyanate (SCN)- anion lattice relaxation that occurs when a Li+ cation jumps to the next available site. Two possible migration models are proposed: the first model considers an asymmetric energy landscape for Li+ cation hopping, while the second model is connected to the jump relaxation model and allows for 180° rotational disorder of the (SCN)- anion. A complete kinetic analysis for the hopping of Li+ cations is presented, which reveals new fundamental insights into the ion transport mechanism of materials with complex anions.

Ion transport mechanism in anhydrous lithium thiocyanate LiSCN Part I: ionic conductivity and defect chemistry.

This work reports on the ion transport properties and defect chemistry in anhydrous lithium thiocyanate Li(SCN), which is a pseudo-halide Li+ cation conductor. An extensive doping study was conducted, employing magnesium, zinc and cobalt thiocyanate as donor dopants to systematically vary the conductivity and derive a defect model. The investigations are based on impedance measurements and supported by other analytical techniques such as X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, and density functional theory (DFT) calculations. The material was identified as Schottky disordered with lithium vacancies being the majority mobile charge carriers. In the case of Mg2+ as dopant, defect association with lithium vacancies was observed at low temperatures. Despite a comparably low Schottky defect formation enthalpy of (0.6 ± 0.3) eV, the unexpectedly high lithium vacancy migration enthalpy of (0.89 ± 0.08) eV distinguishes Li(SCN) from the chemically related lithium halides. A detailed defect model of Li(SCN) is presented and respective thermodynamic and kinetic data are given. The thiocyanate anion (SCN)- has a significant impact on ion mobility due to its anisotropic structure and bifunctionality in forming both Li-N and Li-S bonds. More details about the impact on ion dynamics at local and global scale, and on the defect chemical analysis of the premelting regime at high temperatures are given in separate publications (Part II and Part III).

Poly(ethylene glycol)-poly(ε-caprolactone)-based micelles for solubilization and tumor-targeted delivery of silibinin.

Introduction: Silibinin is a naturally occurring compound with known positive impacts on prevention and treatment of many types of human illnesses in general and cancer in particular. Silibinin is poorly water soluble which results in its insufficient bioavailability and lack of therapeutic efficacy in cancer. Here, we proposed to examine the potential of micelles composed of poly(ethylene glycol) (PEG) as the hydrophilic block and poly(ε-caprolactone) (PCL), poly(α-benzylcarboxylate-ε-caprolactone) (PBCL), or poly(lactide)-(PBCL) (PLA-PBCL) as hydrophobic blocks for enhancing the water solubility of silibinin and its targeted delivery to tumor. Methods: Co-solvent evaporation method was used to incorporate silibinin into PEG-PCL based micelles. Drug release profiles were assessed using dialysis bag method. MTT assay also was used to analyze functional activity of drug delivery in B16 melanoma cells. Results: Silibinin encapsulated micelles were shown to be less than 60 nm in size. Among different structures under study, the one with PEG-PBCL could incorporate silibinin with the highest encapsulation efficiency being 95.5%, on average. PEG-PBCL micelles could solubilize 1 mg silibinin in 1 mL water while the soluble amount of silibinin was found to be 0.092 mg/mL in the absence of polymeric micelles. PEG-PBCL micelles provided the sustained release of silibinin indicated with less than 30% release of silibinin within 24 hours. Silibinin encapsulated in PEG-PBCL micelles resulted in growth inhibitory effect in B16 cancer cells which was significantly higher than what observed with free drug. Conclusion: Our findings showed that PEG-PBCL micellar nanocarriers can be a useful vehicle for solubilization and targeted delivery of silibinin.