In vitro and In vivo Antitumor Activity of the Novel Derivatized Polyvinyl Alcohol-Based Polymer P10(4)

Polyvinyl Alcohol Carbazate as a Polymer-Based Antitumoral Agent

Development of treatment resistance is a major concern during treatment of cancer, and there is an unmet need for therapeutic strategies with novel modes of action. Polyvinyl alcohol carbazate (PVAC) is a polymer compound with unique biological properties. Herein, we describe the antitumoral effects of PVAC. Three well-established cell lines GIST-T1, B16.F10, and A375 were used to determine the in vitro antitumoral effects of PVAC. Assessments included light microscopy, cell viability, cell cycle, and apoptosis assays. In vivo treatment safety and efficacy were characterized in one immunocompetent (B16.F10) mouse model and one athymic nude (MDA-MB-231) mouse model. Excised tumors were measured, weighed, stained for Ki-67, CD3, and histopathologically evaluated. Intact PVAC expressed a non-linear dose-response antitumoral effect in vitro, whereas its separate components, PVA and carbazate, did not display antitumoral effects alone. In vivo, PVAC induced a significant intratumoral CD3⁺ T-cell recruitment in immunocompetent mice (B16.F10), which was associated with tumor growth inhibition. Although growth inhibition was not significant in athymic mice (MDA-MB-231), histopathological evaluation detected an increase in stromal tissue and leukocyte infiltration. In conclusion, we present evidence for PVAC antitumoral effects both in vitro and in vivo. The mode of action was not elucidated in vitro, but a potential mechanism of in vivo activity was observed, characterized by an increase of immune cells into both immunocompetent and athymic mice. This finding warrants further study to validate its possible role as an immunomodulatory polymeric agent.

Nanoparticles combined with growth factors: recent progress and applications

Increasing attention has been focused on the applications of nanoparticles combined with growth factors (NPs/GFs) due to the substantial functions of GFs in regenerative medicine and disease treatments.

Epiregulin induces human SK-N-BE cell differentiation through ERK1/2 signaling pathway

Epidermal growth factor (EGF) and other EGF-related growth factors, such as transforming growth factor-α, are able to stimulate neuroblastoma (NB) cell proliferation. Epiregulin (Epi) is a growth factor belonging to the EGF family known to be more potent than EGF in mediating mitogenic signals. In this study, we tested the ability of Epi to stimulate a human NB cell line (SK-N-BE) proliferation. Surprisingly, Epi (50-1000 ng/ml) induced a reduction in SK-N-BE proliferation along with a morphological differentiation, associated with an increase in MMP-9 expression. Moreover, Epi-induced differentiation was inhibited by ERK1/2 phosphorilation inhibition. In conclusion, Epi could represent a novel and useful tool to oppose NB cell proliferation.

Zinc oxide nanoparticles for selective destruction of tumor cells and potential for drug delivery applications

IMPORTANCE OF THE FIELD

Metal oxide nanoparticles, including zinc oxide, are versatile platforms for biomedical applications and therapeutic intervention. There is an urgent need to develop new classes of anticancer agents, and recent studies demonstrate that ZnO nanomaterials hold considerable promise.

AREAS COVERED IN THIS REVIEW

This review analyzes the biomedical applications of metal oxide and ZnO nanomaterials under development at the experimental, preclinical and clinical levels. A discussion regarding the advantages, approaches and limitations surrounding the use of metal oxide nanoparticles for cancer applications and drug delivery is presented. The scope of this article is focused on ZnO, and other metal oxide nanomaterial systems, and their proposed mechanisms of cytotoxic action, as well as current approaches to improve their targeting and cytotoxicity against cancer cells.

WHAT THE READER WILL GAIN

This review aims to give an overview of ZnO nanomaterials in biomedical applications.

TAKE HOME MESSAGE

Through a better understanding of the mechanisms of action and cellular consequences resulting from nanoparticles interactions with cells, the inherent toxicity and selectivity of ZnO nanoparticles against cancer may be improved further to make them attractive new anticancer agents.

New approaches to pharmacotherapy of tumors of the nervous system during childhood and adolescence

Tumors of the nervous system are among the most common and most chemoresistant neoplasms of childhood and adolescence. Malignant tumors of the brain collectively account for 21% of all cancers and 24% of all cancer-related deaths in this age group. Neuroblastoma, a peripheral nervous system tumor, is the most common extracranial solid tumor of childhood, and 65% of children with this tumor have only a 10 or 15% chance of living 5 years beyond the time of initial diagnosis. Novel pharmacological approaches to nervous system tumors are urgently needed. This review presents the role of and current challenges to pharmacotherapy of malignant tumors of the nervous system during childhood and adolescence and discusses novel approaches aimed at overcoming these challenges.

Amphiphilic poly(vinyl alcohol) derivatives as complexing agents for fenretinide

Poly(vinyl alcohol) (PVA) substituted with oleyl chains and tetraethyleneglycol monoethyl ether chains (TEGMEE) at 1.5% and 1% degrees of substitution respectively (mol of substituent to mol of hydroxyvinyl monomer) has previously been shown to self-assemble in water, providing aggregates selectively cytotoxic toward tumor cells vs normal cells. These polymers have also been shown to increase the long-term survival of nude mice injected with both human and murine neuroblastoma cell lines. In the present work, we changed the substitution degree of the oleyl chains on the poly(vinyl alcohol) backbone and maintained constant at 1% the degree of TEGMEE substitution. We evaluated the main physicochemical characteristics of the final polymers, their cytotoxicity toward tumor cells, and their complexing ability for hydrophobic molecules. The aim was to investigate the possibility of improving intrinsic antitumor efficacy of the polymer by changing the degree of oleyl chain substitution and further increase activity by complexation with antitumor drugs. The polymers were prepared at oleyl chain substitution degrees ranging from 0.5 to 3% (mol of substituent to mol of hydroxyvinyl monomer). The most active was again the 1.5% substituted polymer. It was further characterized by exhibiting the highest complexing ability toward hydrophobic molecules allowing the formation of a complex with fenretinide (HPR). The polymer-HPR complex was stable in aqueous environment and released the free drug prevalently in the presence of fluid hydrophobic phases. It was cytotoxic toward tumor cells with minimal activity toward normal cells. Antitumor activity exceeded that of the separate complex components resulting from the concomitant effect of the polymer and the HPR solubilized by complexation.