Claudia Ferroni

Mesenchymal stem cells as delivery vehicle of porphyrin loaded nanoparticles: Effective photoinduced in vitro killing of osteosarcoma

Mesenchymal stem cells (MSC) have the unique ability to home and engraft in tumor stroma. These features render them potentially a very useful tool as targeted delivery vehicles which can deliver therapeutic drugs to the tumor stroma. In the present study, we investigate whether fluorescent core-shell PMMA nanoparticles (FNPs) post-loaded with a photosensitizer, namely meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) and uploaded by MSC could trigger osteosarcoma (OS) cell death in vitro upon specific photoactivation. In co-culture studies we demonstrate using laser confocal microscopy and time lapse imaging, that only after laser irradiation MSC loaded with photosensitizer-coated fluorescent NPs (TPPS@FNPs) undergo cell death and release reactive oxygen species (ROS) which are sufficient to trigger cell death of all OS cells in the culture. These results encourage further studies aimed at proving the efficacy of this novel tri-component system for PDT applications.

Quinazolinedione SIRT6 inhibitors sensitize cancer cells to chemotherapeutics

The NAD(+)-dependent sirtuin SIRT6 is highly expressed in human breast, prostate, and skin cancer where it mediates resistance to cytotoxic agents and prevents differentiation. Thus, SIRT6 is an attractive target for the development of new anticancer agents to be used alone or in combination with chemo- or radiotherapy. Here we report on the identification of novel quinazolinedione compounds with inhibitory activity on SIRT6. As predicted based on SIRT6s biological functions, the identified new SIRT6 inhibitors increase histone H3 lysine 9 acetylation, reduce TNF-α production and increase glucose uptake in cultured cells. In addition, these compounds exacerbate DNA damage and cell death in response to the PARP inhibitor olaparib in BRCA2-deficient Capan-1 cells and cooperate with gemcitabine to the killing of pancreatic cancer cells. In conclusion, new SIRT6 inhibitors with a quinazolinedione-based structure have been identified which are active in cells and could potentially find applications in cancer treatment.

A New Avenue toward Androgen Receptor Pan-antagonists: C2 Sterically Hindered Substitution of Hydroxy-propanamides

The androgen receptor (AR) represents the primary target for prostate cancer (PC) treatment even when the disease progresses toward androgen-independent (AIPC) or castration-resistant (CRPC) forms. Because small chemical changes in the structure of nonsteroidal AR ligands determine the pharmacological responses of AR, we developed a novel stereoselective synthetic strategy that allows sterically hindered C2-substituted bicalutamide analogues to be obtained. Biological and theoretical evaluations demonstrate that C2-substitution with benzyl and phenyl moieties is a new, valuable option toward improving pan-antagonist behavior. Among the synthesized compounds, (R)-16m, when compared to casodex, (R)-bicalutamide, and enzalutamide, displayed very promising in vitro activity toward five different prostate cancer cell lines, all representative of CPRC and AIPC typical mutations. Despite being less active than (R)-bicalutamide, (R)-16m also displayed marked in vivo antitumor activity on VCaP xenografts and thus it may serve as starting point for developing novel AR pan-antagonists.

TPPS supported on core–shell PMMA nanoparticles: the development of continuous-flow membrane-mediated electrocoagulation as a photocatalyst processing method in aqueous media

Herein, the successful utilization of core shell poly-methyl methacrylate nanoparticles (CS-PMMA NPs) as a valuable support for organocatalyst immobilization in aqueous medium is presented along with an unprecedented direct current-based electrochemical method for processing a water colloid of the resulting nano-supported catalyst. The NP coagulation procedure relied on various electrocoagulation techniques and it was achieved through water electrolysis occurring in a dialysis membrane immersed in the colloid. Mass recoveries of up to 95% w/w were obtained for the NPs within 1 h of electrolysis. This was optimized at a constant current of 90 mA or a constant potential of 24 V. The disclosed NP separation procedure was effectively exploited in a continuous-flow reaction/separation/recycle sequence involving the tetraphenylporphyrin tetrasulfonate (TPPS) organo-photocatalyst immobilized on CS-PMMA NPs (NP2s). After an optimization study aimed at maximizing the chemical efficiency of the entire synthetic and purification process, the nano-supported catalyst NP2 (0.05 mol%) efficiently promoted the photoexcitation of triplet oxygen to singlet oxygen for the selective and environmentally benign sulfoxidation of a model sulfide in an aqueous medium.

Elucidating new structural features of the triazole scaffold for the development of mPGES-1 inhibitors

We report a new potent revisited version of a triazole-based inhibitor obtained by structure-based drug design on the human mPGES-1 crystal structure. Moreover, we disclosed the substitution with a halogen atom at position 5 as a new key factor influencing the biological activity on the mPGES-1 enzyme.

Androgen Receptor Targeted Conjugate for Bimodal Photodynamic Therapy of Prostate Cancer in Vitro

Prostate cancer (PC) represents the most common type of cancer among males and is the second leading cause of cancer death in men in Western society. Current options for PC therapy remain unsatisfactory, since they often produce uncomfortable long-term side effects, such as impotence (70%) and incontinence (5-20%) even in the first stages of the disease. Light-triggered therapies, such as photodynamic therapy, have the potential to provide important advances in the treatment of localized and partially metastasized prostate cancer. We have designed a novel molecular conjugate (DR2) constituted of a photosensitizer (pheophorbide a, Pba), connected to a nonsteroidal anti-androgen molecule through a small pegylated linker. This study aims at investigating whether DR2 represents a valuable approach for PC treatment based on light-induced production of single oxygen and nitric oxide (NO) in vitro. Besides being able to efficiently bind the androgen receptor (AR), the 2-trifluoromethylnitrobenzene ring on the DR2 backbone is able to release cytotoxic NO under the exclusive control of light, thus augmenting the general photodynamic effect. Although DR2 is similarly internalized in cells expressing different levels of androgen receptor, the AR ligand prevents its efflux through the ABCG2-pump. In vitro phototoxicity experiments demonstrated the ability of DR2 to kill cancer cells more efficiently than Pba, while no dark toxicity was observed. Overall, the presented approach is very promising for further development of AR-photosensitizer conjugates in the multimodal photodynamic treatment of prostate cancer.

Chlorin e6 keratin nanoparticles for photodynamic anticancer therapy

This work describes the preparation of keratin and chlorin e6-conjugated keratin nanoparticles, KNPs and KNPs@Ce6 respectively, by comparing self-assembling and desolvation methodologies. Nanoparticles were characterized in terms of yield, size, morphology, Ce6 loading ratio and ability to produce reactive oxygen species (ROS) upon irradiation with white light. Overall, both methods provided nanoparticles of comparable dimensions, morphology and Ce6 loading ratio. KNPs@Ce6 obtained by a self-assembling procedure were able to produce ROS in a concentration and irradiation-time dependent manner, while displaying compelling evidence of their photostability. In vitro internalization and photo-toxicity studies were performed on osteosarcoma (U2OS) and glioblastoma (U87) cells lines to assess the ability of KNPs@Ce6 nanoparticles to act as delivery systems for photodynamic therapy of cancer. Importantly, at all the Ce6 considered concentrations, e.g. 0.5, 2.5 and 5.0 μg mL−1, no dark toxicity was detected while the amount of Ce6 inside the cells, significantly increased when loaded onto KNPs. The irradiation of tumor cells loaded with KNPs@Ce6 resulted in a greater cell death percentage (approximately 90%) as compared to free Ce6 in both cell types and at all the considered concentrations, thus showing KNPs as effective and promising delivery vehicles for photodynamic therapy applications.

A photodynamic bifunctional conjugate for prostate cancer: an in vitro mechanistic study

SummaryPhotodynamic therapy (PDT) has drawn considerable attention for its efficacy against certain types of cancers. It shows however limits in the case of deep cancers, favoring tumor recurrence under suboptimal conditions. More insight into the molecular mechanisms of PDT-induced cytotoxicity and cytoprotection is essential to extend and strengthen this therapeutic modality. As PDT induces iNOS/NO in both tumor and microenvironment, we examined the role of nitric oxide (NO) in cytotoxicity and cytoprotection. Our findings show that NO mediates its cellular effects by acting on the NF-κB/YY1/RKIP loop, which controls cell growth and apoptosis. The cytoprotective effect of PDT-induced NO is observed at low NO levels, which activate the pro-survival/anti-apoptotic NF-κB and YY1, while inhibiting the anti-survival/pro-apoptotic and metastasis suppressor RKIP. In contrast, high PDT-induced NO levels inhibit NF-κB and YY1 and induce RKIP, resulting in significant anti-tumor activity. These findings reveal a critical role played by NO in PDT and suggest that the use of bifunctional PDT agents composed of a photosensitizer and a NO-donor could enhance the photo-treatment effect. A successful application of NO in anticancer therapy requires control of its concentration in the target tissue. To address this issue we propose as PDT agent, a bimolecular conjugate called DR2, composed of a photosensitizer (Pheophorbide a) and a non-steroidal anti-androgen molecule capable of releasing NO under the exclusive control of light. The mechanism of action of DR2 in prostate cancer cells is reported and discussed.

Polyenylcyclopropane carboxylic esters with high insecticidal activity

BACKGROUND Pyrethroids are synthetic derivatives of naturally occurring pyrethrum. These molecules are widely used in agriculture for ant, fly and mosquito control and for lawn and garden care. Pyrethroids are the optically active esters of 2,2-dimethyl-3-(2-methylpropenyl)-cyclopropane carboxylic acid, also known as chrysanthemic acid. However, their intense use has resulted in the development of resistance in many insect species. Herein, specific structural modifications of the pyrethroid scaffold and their effect on insecticidal activity, especially on resistant pests strains, are reported. RESULTS The exposure to (1R)-trans-(E/Z)-2,3,5,6-tetrafluorobenzyl-3-(buta-1,3-dienyl)-2,2-dimethyl cyclopropanecarboxylate and its diastereomers produced 100% mortality in yellow fever mosquitoes (Aedes aegypti), house mosquitoes (Culex quinquefasciatus) and houseflies (Musca domestica). Moreover, this compound provided complete knockdown within 15 min of exposure against cockroaches (Blattella germanica) and maintained an excellent knockdown activity at 10 days after treatment. CONCLUSION Novel pyrethroid derivatives obtained from 2,2-dimethyl-3-(2-methylpropenyl)-cyclopropanecarboxylic acid are described. These derivatives display high insecticidal activity, a wide spectrum of action and no toxicity towards mammalians. The proposed synthetic procedures are highly efficient and inexpensive, and therefore suitable for industrial scale-up.

Camptothecin and Thiocamptothecin: the Role of Sulfur in Shifting the Hydrolysis Equilibrium towards the Closed Lactone Form

Adverse effects have limited the clinical potential of 20‐(S)‐camptothecin (CPT) and led to a growing interest in the development of CPT analogues that exhibit less severe drawbacks, while maintaining their therapeutic activity. Recently, a thiopyridone isostere of CPT, 20‐(S)‐thiocamptothecin (TCPT), was developed that resulted more potent than the parent compound in H460, HT29 and IGROV‐1 cell lines. The improved activity of TCPT over CPT might be due to the greater stability of the lactone ring. Here, reversible hydrolysis to the ring‐open carboxylate forms of CPT and TCPT was studied by HPLC, both in the presence and absence of human serum albumin (HSA). The amount of TCPT that exists in the lactone form at equilibrium in buffer solution (24 h) was found to be significantly higher than CPT, and the same trend was observed in the presence of HSA. Specifically, HSA caused a shift in the hydrolysis equilibrium of TCPT towards the carboxylate form, but the proportion of lactone form remained higher than that observed for CPT under the same conditions, and also in the presence of a higher excess of the protein. The role of the sulfur atom in the stability of the open and closed lactone derivatives was investigated by theoretical calculations using stabilization energies and comparison between experimental and calculated absorption spectra. Our results suggest that, in aqueous solution, more ionic species (anionic and enolic forms) are present for TCPT. This study provides further insights into the effects of oxygen/sulfur replacement in the CPT pyridone ring.