Pyridoclax-loaded nanoemulsion for enhanced anticancer effect on ovarian cancer.

BACKGROUND: Pyridoclax is an original lead, recently identified as very promising in treatment of chemoresistant ovarian cancers. To correct the unfavorable intrinsic physico-chemical properties of this BCS II drug, a formulation strategy was implied in the drug discovery step. Pyridoclax-loaded nanoemulsions (NEs) were developed to permit its preclinical evaluation. RESULTS: The resulting nanoemulsions displayed a mean size of about 100 nm and a high encapsulation efficiency (>95%) at a drug loading of 2 wt%, enabling a 1,000-fold increase of the Pyridoclax apparent solubility. NEs have enabled a sustained release of the drug as assayed by a dialysis bag method. In addition, anti-tumor effects of the Pyridoclax-loaded nanoemulsions (PNEs) showed a 2.5-fold higher activity on chemoresistant ovarian cancer cells than free Pyridoclax. This effect was confirmed by a drastic increase of caspase 3/7 activation from 10 µM PNEs, as newly objectified by real time apoptose imaging. The Pyridoclax bioavailability was kept unchanged after encapsulation in nanoemulsions as determined in a mice model after oral administration. CONCLUSION: Thus, NEs should permit valuable Pyridoclax oral administration, and valorization of this promising anticancer drug by maintaining its original anticancer activity, and by reducing the Pyridoclax therapeutic concentration.

miR-491-5p-induced apoptosis in ovarian carcinoma depends on the direct inhibition of both BCL-XL and EGFR leading to BIM activation.

We sought to identify miRNAs that can efficiently induce apoptosis in ovarian cancer cells by overcoming BCL-X(L) and MCL1 anti-apoptotic activity, using combined computational and experimental approaches. We found that miR-491-5p efficiently induces apoptosis in IGROV1-R10 cells by directly inhibiting BCL-X(L) expression and by inducing BIM accumulation in its dephosphorylated form. This latter effect is due to direct targeting of epidermal growth factor receptor (EGFR) by miR-491-5p and consequent inhibition of downstream AKT and MAPK signalling pathways. Induction of apoptosis by miR-491-5p in this cell line is mimicked by a combination of EGFR inhibition together with a BH3-mimetic molecule. In contrast, SKOV3 cells treated with miR-491-5p maintain AKT and MAPK activity, do not induce BIM and do not undergo cell death despite BCL-XL and EGFR downregulation. In this cell line, sensitivity to miR-491-5p is restored by inhibition of both AKT and MAPK signalling pathways. Altogether, this work highlights the potential of miRNA functional studies to decipher cell signalling pathways or major regulatory hubs involved in cell survival to finally propose the rationale design of new strategies on the basis of pharmacological combinations.

Rapid and soft formulation of folate-functionalized nanoparticles for the targeted delivery of tripentone in ovarian carcinoma.

We report the development of folate-functionalized nanoparticles able to target folate receptors, and to deliver a poorly water soluble cytotoxic agent, a tripentone, in ovarian carcinoma. The stability under incubation of lipid nanoparticles formulated by a low-energy phase inversion temperature method was investigated. Thanks to the presence of Labrasol(®), a macrogolglyceride into the composition of the nanocarriers, the conjugation of different quantities of a folate derivate (folic acid-polyethylene glycol2000-distearylphosphatidylethanolamine) to nanoparticles was possible by a rapid, soft, very simple post-insertion process. As determined by dynamic light scattering, nanoparticles present a monodisperse diameter of about 100 nm, a spherical shape as attested by transmission electron micrographs, a weakly negative surface zeta potential, and are able to encapsulate the tripentone MR22388. The presence of folate receptors on SKOV3 human ovarian cancer cells was identified by fluorescent immunocytochemistry. Cellular uptake studies assessed by flow cytometry indicated that these nanoparticles reached the SKOV3 cells rapidly, and were internalized by a folate-receptor mediated endocytosis pathway. Moreover, nanoparticles allowed the rapid delivery of the antitumor agent tripentone into cells as shown in vitro by real-time cellular activity assay. Such folate-lipid nanoparticles are a potential carrier for targeted delivery of poorly water soluble compounds into ovarian carcinoma.

Absence of Bcl-xL down-regulation in response to cisplatin is associated with chemoresistance in ovarian carcinoma cells.

OBJECTIVE: Recurrence and subsequent acquired chemoresistance to platinum-based treatments constitute major hurdles to ovarian carcinoma therapy. Our objective was to examine the involvement of Bcl-xL anti-apoptotic protein in resistance to cisplatin. METHODS: We described the effect of cisplatin on cell cycle and apoptosis induction in sensitive (IGROV1 and OAW42) and resistant (IGROV1-R10 and SKOV3) ovarian carcinoma cell lines. We correlated it with Bcl-xL mRNA and protein expression after exposure to cisplatin. We then used bcl-xS gene transfer to impede Bcl-xL activity. RESULTS: Our study showed that Bcl-xL basal expression was high in both sensitive and resistant cell lines, as well as in all the studied ovarian tumor samples. Thus, Bcl-xL basal expression could not allow to predict sensitivity. Wondering whether variation of Bcl-xL level in response to cisplatin could be a better determinant of sensitivity, we investigated the expression of this protein in the cell lines after treatment. Cisplatin-induced down-regulation of Bcl-xL was strictly associated with apoptosis and absence of recurrence in vitro. Conversely, the maintenance of Bcl-xL expression in response to cisplatin appeared as a sine qua non condition to escape to treatment. To try to sensitize SKOV3 cells by impeding anti-apoptotic activity of Bcl-xL, we transfected bcl-xS gene in these cells. Bcl-xS exogenous expression was only slightly cytotoxic on its own, but highly sensitized SKOV3 resistant cells to cisplatin-induced apoptosis, and delayed recurrence. CONCLUSION: This work thus provides one more argument to put Bcl-xL forward as a pertinent target of inhibition to overcome chemoresistance of epithelial ovarian carcinoma.