Ilaria Basile

Mannose‐Functionalized Mesoporous Silica Nanoparticles for Efficient Two‐Photon Photodynamic Therapy of Solid Tumors

In the context of national systematic screenings for cancer,photodynamic therapy (PDT) has arisen as an alternative tochemo- and radiotherapy for the non-invasive selectivedestruction of small tumors. PDT involves the use of aphotosensitizer which, upon irradiation at specific wave-lengths, in the presence of oxygen, leads to the generation ofcytotoxic species and consequently to irreversible celldamage.

Heat shock cognate 70 protein secretion as a new growth arrest signal for cancer cells.

Earlier studies indicated that density-arrested cancer cells released an unidentified growth inhibitor whose secretion was prevented by overexpression of the lysosomal protease cathepsin D (cath D). In this study, this growth inhibitor was purified by affinity chromatography and identified as the heat shock cognate 70 protein (hsc70) based on its peptide microsequencing and specific antibody recognition. Among intracellular proteins, including other heat shock proteins, only constitutive hsc70 was secreted in response to the high-cell density. Moreover, hsc70 secretion from cancer cells was generated by serum deprivation, whereas its cellular concentration did not change. Prevention of Hsc70 secretion by cath D overexpression was associated with the formation of multilayer cell cultures, thus indicating a loss of contact inhibition. In addition, we showed that supplementing the culture medium with purified hsc70 inhibited cell proliferation in the nanomolar range. Conversely, removal of this extracellular hsc70 from the medium by either retention on ADP-agarose or competition at the Hsc70 binding site restored cell proliferation. Hsc70 appears active in human breast cancer cells and hypersecreted by direct cath D inhibition. These results suggest a new role of this secreted hsc70 chaperone in cell proliferation that might account for the higher tumor growth of cancer cells overexpressing cath D.

Estrogens promote cell–cell adhesion of normal and malignant mammary cells through increased desmosome formation

The association of estrogen receptor alpha (ERα) expression with differentiated breast tumors presenting a lower metastasis risk could be explained by the estrogen modulation of cell adhesion, motility and invasiveness. Since desmosomes play a crucial role in cell-cell adhesion and may interfere in tumor progression, we studied their regulation by estrogens in human breast cancer and normal mammary cells. Estrogens increased the formation of desmosomes in normal and malignant cells. Furthermore, four desmosomal proteins (desmocollin, γ-catenin, plakophilin and desmoplakin) appeared significantly up-regulated by estrogens in three ERα-expressing cancer cell lines and this effect was reversed by a pure antiestrogen. Finally, silencing of ERα or desmoplakin expression by specific siRNA revealed that estrogen-modulated desmosomal proteins are essential for the estrogenic control of intercellular adhesion. This estrogen modulation of desmosome formation could contribute to the lower invasiveness of ERα-positive tumors and to the integrity of epithelial layers in estrogen target tissues.

Dipeptide mimic oligomer transporter mediates intracellular delivery of Cathepsin D inhibitors: a potential target for cancer therapy.

Implication of the intracellular proteolytic activity of Cathepsin D (CathD), a lysosomal aspartyl-protease overexpressed in numerous solid tumors, has been evidenced on tumor growth. Its intracellular inhibition by potent inhibitors such as pepstatin constitutes a relevant but challenging molecular target. Indeed the potential of pepstatin as a therapeutic molecule is hampered by its too low intracellular penetration. We addressed this limitation by designing and developing a bioconjugate combining a pepstatin derivative with a new vector of cell penetration (CPNP) specifically targeting the endolysosomal compartment. We showed that this pepstatin conjugate (JMV4463) exhibited high anti-proliferative effect on tumor cell cultures via intracellular CathD inhibition and altered cell cycle associated with apoptotic events in vitro. When tested in mice xenografted with breast cancer cells, JMV4463 delayed tumor emergence and growth.

Targeting Multiplicity: The Key Factor for Anti-Cancer Nanoparticles

In this mini-review, we focus on different strategies to bring nanotools specifically to cancer cells. We discuss about a better targeting of tumor, combining the characteristics of tumor environment, the increase in nanoparticles life time, the biomarkers overexpressed on cancer cells and different physical methods for non invasive therapies. Here we detail the necessity of a synergy between passive and active targeting for an actual specificity of cancer cells.

Functionalized Nanoparticles for Drug Delivery, One- and Two-photon Photodynamic Therapy as a Promising Treatment of Retinoblastoma

Retinoblastoma is a rare cancer triggered by genetic mutation that forms in the eyes of children. In industrialized countries, 95% of patients are cured by chemotherapy and conservative treatments. However these treatments can increase the risk of secondary tumors in patients with a constitutional alteration of the retinoblastoma gene Rb1. Photodynamic therapy (PDT) represents a therapeutic approach and may reduce the incidence of secondary tumors. PDT is an established cancer treatment based on the light activation of a photosensitizing agent thus generating cytotoxic reactive oxygen species that cause cellular damage. We focused on mesoporous silica nanoparticles (MSN) for one-photon excited PDT combined with drug delivery and carbohydrate targeting applied on retinoblastoma. We demonstrated that bitherapy (camptothecin delivery and PDT) performed with MSN was efficient in inducing retinoblastoma cell death. Alternatively, MSN designed for two-photon excited PDT were also studied and irradiation in near-infrared at low fluency efficiently killed retinoblastoma cancer cells. These data provide new evidences of the potential of functionalized and targeted MSN for treatment of retinoblastoma and could lead to propose a non-invasive therapy with reduced side effects.

Adiponectin normalization: a clue to the anti-metabolic syndrome action of rimonabant.

Obesity, currently associated with metabolic syndrome is characterized by an excessive fat storage in different organs, in particular adipose tissue, inducing the loss of its structural and functional integrity. Being aware of the importance of adipose tissue endocrine function and the key role of adipocytokines, such as adiponectin, in obesity and metabolic syndrome drives the necessity to develop new drugs that can exert a specific action on adipose tissue and on adiponectin levels. Rimonabant, an antiobesity drug, presents a dual effect by decreasing food intake and importantly increasing adiponectin. This review focuses on the key role of adiponectin regulation in the success of rimonabant and suggests that this adipohormone may be considered as a therapeutic target to design innovative and promising antiobesity and anti-metabolic syndrome drugs.

Roles of Estrogen Receptor and p21Waf1 in Bortezomib-Induced Growth Inhibition in Human Breast Cancer Cells

Proteasome inhibitors such as bortezomib constitute novel therapeutic agents that are currently in clinical use and in clinical trials. In some neoplasms, cyclin-dependent kinase inhibitors (CKI) such as p21WAF1 have been proposed as key targets of proteasome inhibitors. p21WAF1 expression can be modulated by p53, a tumor suppressor, and especially in breast cancer cells, by estrogen receptor alpha (ERα), which is highly relevant to cancer growth. We investigated the effects of bortezomib using a panel of six cancer cell lines with variable status of ERα or p53 and found that bortezomib inhibited the growth of all cell lines in the same concentration range irrespective of the ERα expression or the mutational status of p53. Bortezomib treatment significantly enhanced p21WAF1 protein levels in all cell lines but with different mechanisms according to ERα status. In ERα-positive cells, bortezomib treatment caused a strong increase in p21WAF1 mRNA, whereas in ERα-negative cells it predominantly enhanced p21WAF1 protein levels suggesting a posttranslational mechanism of p21WAF1 regulation in the ERα-negative cells. Moreover, the antiproliferative activity of bortezomib was prevented by ERα silencing or p21WAF1 knockdown in ERα-positive cells. Collectively, our results highlight the potential roles of ERα and p21WAF1 in growth inhibition of cancer cells mediated by proteasome inhibitors, such as bortezomib. Mol Cancer Res; 10(11); 1473–81. ©2012 AACR.

Efficient therapy for refractory Pompe disease by mannose 6-phosphate analogue grafting on acid α-glucosidase

Abstract Pompe disease is a rare disorder due to deficiency of the acid &agr;‐glucosidase (GAA) treated by enzyme replacement therapy. The present authorized treatment with rhGAA, the recombinant human enzyme, provides an important benefit in the infantile onset; however, the juvenile and adult forms of the disease corresponding to > 80% of the patients are less responsive to this treatment. This resistance has been mainly attributed to an insufficiency of mannose 6‐phosphate residues in rhGAA to address lysosomes through the cation‐independent mannose 6‐phosphate receptor (CI‐M6PR). As yet, several attempts to improve the enzyme delivery by increasing the number of mannose 6‐phosphate on the enzyme were poorly effective on the late onset form of the disease. Here, we show that chemical conjugation of a synthetic analogue of the mannose 6‐phosphate, named AMFA, onto rhGAA improves the affinity for CI‐M6PR and the uptake of the enzyme in fibroblasts and myoblasts of adult Pompe patients. More importantly, only the conjugated rhGAA‐AMFA was effective in aged Pompe mice when compared to rhGAA. Weekly treatment with 5–20 mg·kg− 1 rhGAA‐AMFA provided major improvements of the motor function and of the myofiber structure, whereas rhGAA was inactive. Finally, AMFA addition did not induce supplementary immune response to the enzyme. This modified enzyme, displaying a muscle recovery in aged Pompe mice that was never attained before, could be considered as a potential therapy for the late onset Pompe disease. Graphical abstract Figure. No Caption available.

Design of Potent Mannose 6-Phosphate Analogues for the Functionalization of Lysosomal Enzymes To Improve the Treatment of Pompe Disease

Improving therapeutics delivery in enzyme replacement therapy (ERT) for lysosomal storage disorders is a challenge. Herein, we present the synthesis of novel analogues of mannose 6-phosphate (M6P), known as AMFAs and functionalized at the anomeric position for enzyme grafting. AMFAs are non-phosphate serum-resistant derivatives that efficiently bind the cation-independent mannose 6-phosphate receptor (CI-M6PR), which is the main pathway to address enzymes to lysosomes. One of the AMFAs was used to improve the treatment of the lysosomal myopathy Pompe disease, in which acid α-glucosidase (GAA) is defective. AMFA grafting on a M6P-free recombinant GAA led to a higher uptake of the GAA in adult Pompe fibroblasts in culture as compared to Myozyme, the M6P recombinant GAA. Moreover, the treatment of Pompe adult mice with the AMFA-grafted recombinant enzyme led to a remarkable improvement, even at low doses, in muscle functionality and regeneration, whereas Myozyme had limited efficacy.