Alteration of ribosome function upon 5-fluorouracil treatment favors cancer cell drug-tolerance.

Mechanisms of drug-tolerance remain poorly understood and have been linked to genomic but also to non-genomic processes. 5-fluorouracil (5-FU), the most widely used chemotherapy in oncology is associated with resistance. While prescribed as an inhibitor of DNA replication, 5-FU alters all RNA pathways. Here, we show that 5-FU treatment leads to the production of fluorinated ribosomes exhibiting altered translational activities. 5-FU is incorporated into ribosomal RNAs of mature ribosomes in cancer cell lines, colorectal xenografts, and human tumors. Fluorinated ribosomes appear to be functional, yet, they display a selective translational activity towards mRNAs depending on the nature of their 5'-untranslated region. As a result, we find that sustained translation of IGF-1R mRNA, which encodes one of the most potent cell survival effectors, promotes the survival of 5-FU-treated colorectal cancer cells. Altogether, our results demonstrate that "man-made" fluorinated ribosomes favor the drug-tolerant cellular phenotype by promoting translation of survival genes.

Circulating Tumor Cell Lines: an Innovative Tool for Fundamental and Translational Research.

Metastasis is a leading cause of cancer death. Despite improvements in treatment strategies, metastatic cancer has a poor prognosis. We thus face an urgent need to understand the mechanisms behind metastasis development, and thus to propose efficient treatments for advanced cancer. Metastatic cancers are hard to treat, as biopsies are invasive and inaccessible. Recently, there has been considerable interest in liquid biopsies including both cell-free circulating deoxyribonucleic acid (DNA) and circulating tumor cells from peripheral blood and we have established several circulating tumor cell lines from metastatic colorectal cancer patients to participate in their characterization. Indeed, to functionally characterize these rare and poorly described cells, the crucial step is to expand them. Once established, circulating tumor cell (CTC) lines can then be cultured in suspension or adherent conditions. At the molecular level, CTC lines can be further used to assess the expression of specific markers of interest (such as differentiation, epithelial or cancer stem cells) by immunofluorescence or cytometry analysis. In addition, CTC lines can be used to assess drug sensitivity to gold-standard chemotherapies as well as to targeted therapies. The ability of CTC lines to initiate tumors can also be tested by subcutaneous injection of CTCs in immunodeficient mice. Finally, it is possible to test the role of specific genes of interest that might be involved in cancer dissemination by editing CTC genes, by short hairpin ribonucleic acid (shRNA) or Crispr/Cas9. Modified CTCs can thus be injected into immunodeficient mouse spleens, to experimentally mimic part of the metastatic development process in vivo. In conclusion, CTC lines are a precious tool for future research and for personalized medicine, where they will allow prediction of treatment efficiency using the very cells that are originally responsible for metastasis.

Stapled peptide targeting the CDK4/Cyclin D interface combined with Abemaciclib inhibits KRAS mutant lung cancer growth.

CDK4/cyclin D kinase constitutes an attractive pharmacological target for development of anticancer therapeutics, in particular in KRAS-mutant lung cancer patients, who have a poor prognosis and no targeted therapy available yet. Although several ATP-competitive inhibitors of CDK4 have been developed for anticancer therapeutics, they suffer from limited specificity and efficacy. Methods: As an alternative to ATP-competitive inhibitors we have designed a stapled peptide to target the main interface between CDK4 and cyclin D, and have characterized its physico-chemical properties and affinity to bind cyclin D1. Results: We have validated a positive correlation between CDK4/cyclin D level and KRAS mutation in lung cancer patients. The stapled peptide enters cells rapidly and efficiently, and inhibits CDK4 kinase activity and proliferation in lung cancer cells. Its intrapulmonary administration in mice enables its retention in orthotopic lung tumours and complete inhibition of their growth when co-administered with Abemaciclib. Conclusion: The stapled peptide targeting the main interface between CDK4 and cyclin D provides promising therapeutic perspectives for patients with lung cancer.

The health status alters the pituitary function and reproduction of mice in a Cxcr2-dependent manner.

Microbiota and chronic infections can affect not only immune status, but also the overall physiology of animals. Here, we report that chronic infections dramatically modify the phenotype of Cxcr2 KO mice, impairing in particular, their reproduction ability. We show that exposure of Cxcr2 KO females to multiple types of chronic infections prevents their ability to cycle, reduces the development of the mammary gland and alters the morphology of the uterus due to an impairment of ovary function. Mammary gland and ovary transplantation demonstrated that the hormonal contexture was playing a crucial role in this phenomenon. This was further evidenced by alterations to circulating levels of sex steroid and pituitary hormones. By analyzing at the molecular level the mechanisms of pituitary dysfunction, we showed that in the absence of Cxcr2, bystander infections affect leukocyte migration, adhesion, and function, as well as ion transport, synaptic function behavior, and reproduction pathways. Taken together, these data reveal that a chemokine receptor plays a direct role in pituitary function and reproduction in the context of chronic infections.

ABMA, a small molecule that inhibits intracellular toxins and pathogens by interfering with late endosomal compartments.

Intracellular pathogenic microorganisms and toxins exploit host cell mechanisms to enter, exert their deleterious effects as well as hijack host nutrition for their development. A potential approach to treat multiple pathogen infections and that should not induce drug resistance is the use of small molecules that target host components. We identified the compound 1-adamantyl (5-bromo-2-methoxybenzyl) amine (ABMA) from a cell-based high throughput screening for its capacity to protect human cells and mice against ricin toxin without toxicity. This compound efficiently protects cells against various toxins and pathogens including viruses, intracellular bacteria and parasite. ABMA provokes Rab7-positive late endosomal compartment accumulation in mammalian cells without affecting other organelles (early endosomes, lysosomes, the Golgi apparatus, the endoplasmic reticulum or the nucleus). As the mechanism of action of ABMA is restricted to host-endosomal compartments, it reduces cell infection by pathogens that depend on this pathway to invade cells. ABMA may represent a novel class of broad-spectrum compounds with therapeutic potential against diverse severe infectious diseases.

Lanthanide-based peptide biosensor to monitor CDK4/cyclin D kinase activity.

We describe a lanthanide biosensor that responds to CDK4 kinase activity in melanoma cell extracts through a significant and dose dependent increase in luminescence, thanks to sensitization of a DOTA[Tb3+] complex incorporated into a CDK4 substrate peptide by a unique tryptophan residue in an adjacent phosphoaminoacid binding moiety.

IL-1ß produced by aggressive breast cancer cells is one of the factors that dictate their interactions with mesenchymal stem cells through chemokine production.

The aim of this work was to understand whether the nature of breast cancer cells could modify the nature of the dialog of mesenchymal stem cells (MSCs) with cancer cells. By treating MSCs with the conditioned medium of metastatic Estrogen-receptor (ER)-negative MDA-MB-231, or non-metastatic ER-positive MCF-7 breast cancer cells, we observed that a number of chemokines were produced at higher levels by MSCs treated with MDA-MB-231 conditioned medium (CM). MDA-MB-231 cells were able to induce NF-κB signaling in MSC cells. This was shown by the use of a NF-kB chemical inhibitor or an IκB dominant negative mutant, nuclear translocation of p65 and induction of NF-κB signature. Our results suggest that MDA-MB-231 cells exert their effects on MSCs through the secretion of IL-1ß, that activates MSCs and induces the same chemokines as the MDA-MB-231CM. In addition, inhibition of IL-1ß secretion in the MDA-MB-231 cells reduces the induced production of a panel of chemokines by MSCs, as well the motility of MDA-MB-231 cells. Our data suggest that aggressive breast cancer cells secrete IL-1ß, which increases the production of chemokines by MSCs.

Inhibitors of the cellular trafficking of ricin.

Throughout the last decade, efforts to identify and develop effective inhibitors of the ricin toxin have focused on targeting its N-glycosidase activity. Alternatively, molecules disrupting intracellular trafficking have been shown to block ricin toxicity. Several research teams have recently developed high-throughput phenotypic screens for small molecules acting on the intracellular targets required for entry of ricin into cells. These screens have identified inhibitory compounds that can protect cells, and sometimes even animals against ricin. We review these newly discovered cellular inhibitors of ricin intoxication, discuss the advantages and drawbacks of chemical-genetics approaches, and address the issues to be resolved so that the therapeutic development of these small-molecule compounds can progress.

Coadministration of nanosystems of short silencing RNAs targeting oestrogen receptor alpha and anti-oestrogen synergistically induces tumour growth inhibition in human breast cancer xenografts.

The suppression of oestrogen receptor alpha (ERalpha) functions by silencing RNAs in association with or not with anti-oestrogens (AEs) both in vitro and in breast cancer cell xenografts was assessed. In vitro, a prolonged decrease in ERalpha protein expression and an enhanced AE-induced inhibition of ERalpha-mediated transcription, together with antiproliferative activity, were observed. Incorporation of ERalpha-siRNAs in pegylated nanocapsules (NC) was achieved; and their intravenous injections in MCF-7 xenografts, in contrast to scramble siRNA containing NCs, lead to decrease in ERalpha protein content and Ki67 labelling in tumour cells. The pure AE RU58668 (RU) both free and entrapped in stealth nanospheres (NS) at very low concentration (8 microg/kg/week) had no effect on tumour growth evolution. However, coinjection of the two nanocarriers potentiated the decrease in ERalpha protein, concomitantly with decreasing tumour vasculature and glucose transporter-1. These data support that the targeted delivery of ERalpha-siRNA in breast tumours potentiates the inhibition of E(2)-induced proliferative activity by encapsulated AE through enhanced anti-vascular activity. In the hormone-independent MDA-MB-231 xenograft model, RU-NS at 4 mg/kg/week induce also a strong tumour vascular normalisation. Together, these findings suggest that the anti-oestrogen activity of RU as well as that of targeted ERalpha-siRNA leads to anti-angiogenic activity. Their delivery in stealth nanocarriers may constitute a new anti-cancer therapeutic strategy in solid tumours.

Lipoplexes targeting the CD44 hyaluronic acid receptor for efficient transfection of breast cancer cells.

Lipoplexes containing a hyaluronic acid-dioleoylphosphatidylethanolamine (HA-DOPE) conjugate were designed to target the CD44 receptor on breast cancer cells. Cationic liposomes composed of a mixture of [2-(2,3-didodecyloxypropyl)hydroxyethyl]ammonium bromide (DE) and dioleoylphosphatidylethanolamine (DOPE) with or without HA-DOPE were prepared, characterized, and used to form a complex with plasmid DNA pCMV-luc. Lipoplexes displayed a negative zeta potential and a mean diameter between 250-300 nm. Cytotoxicity and transfection efficiency of the lipoplexes were determined on the MDA-MB-231and MCF-7 breast cancer cell lines. Cytotoxicity was not modified by the presence of HA-DOPE. However HA-DOPE increased the level of transfection on CD44-expressing MDA-MB-231 cells compared to the MCF-7 line, which expresses very low levels of CD44. The transfection on the MDA-MB-231 cells was highly inhibited by anti-CD44 Hermes-1 antibody but not by the nonspecific anti-ErbB2 antibody. In conclusion, cationic liposomes containing the HA-DOPE conjugate mediated good transfection on CD44 expressing cell lines in culture.

Tosylcyclonovobiocic acids promote cleavage of the hsp90-associated cochaperone p23.

The cochaperone p23 is required for the chaperoning cycle of hsp90 and to enhance the maturation of several client proteins. Tosylcyclonovobiocic acids (4TCNA and 7TCNA) are potent analogs of novobiocin and induce cell cycle arrest, apoptosis and degradation of hsp90 client proteins in a panel of cancer cells. In this study, Western blotting shows that 4TCNA and 7TCNA triggered processing of the hsp90 cochaperone p23 in a dose-dependent manner. Small interfering RNA (siRNA)-mediated reduction of p23 expression in MCF-7 breast cancer cells did not block 4TCNA-induced caspase activation as assessed by the cleavage of PARP. This result indicates that 4TCNA-mediated cell death is a p23-independent process. In HT29 colon cancer cells, 4TCNA and 7TCNA up-regulated GRP78 and GRP94 supporting involvement of ER stress in apoptosis.

Physicochemical characteristics and preliminary in vivo biological evaluation of nanocapsules loaded with siRNA targeting estrogen receptor alpha.

Specific siRNAs that target estrogen receptor alpha (ERalpha) were encapsulated in nanocapsules (NCs). We produced small (approximately 100-200 nm) ERalpha-siRNA NCs with a water core by incorporating two mixed duplexes of specific ERalpha-siRNAs (ERalpha-mix-siRNA) into NCs. The encapsulation yield that was obtained with poly(iso-butylcyanoacrylate) (PIBCA) NCs was low, whereas no release of trapped siRNA was observed for poly(ethylene)glycol-poly(D,L-lactide-co-glycolide) (PEG-PLGA) NCs. High levels of ERalpha-siRNA incorporation into PEG-epsilon-caprolactone-malic acid (PEG-PCL/MA) NCs (3.3 microM in a polymer solution at 16 mg/mL) were observed (72% yield). No difference in size or zeta potential was observed between siRNA NCs that were based on PEG-PCL/MA and empty NCs. Fluorescence quenching assays confirmed the incorporation of siRNA into the NC core. A persistent loss of ERalpha (90% over 5 days) was observed in MCF-7 human breast cancer cells that were exposed to PEG-PCL/MA NCs that were loaded with ERalpha-siRNA. The intravenous injection of these NCs into estradiol-stimulated MCF-7 cell xenografts led to a significant decrease in tumor growth and a decrease in ERalpha expression in tumor cells. These data indicate that a novel strategy, based on ERalpha-siRNA delivery, could be developed for the treatment of hormone-dependent breast cancers.

Antioestrogen-mediated cell cycle arrest and apoptosis induction in breast cancer and multiple myeloma cells.

Antioestrogens (AEs) are synthetic molecules that block proliferation and induce apoptosis in breast cancer (BC) cells, principally by competing with oestradiol for binding to oestrogen receptors. Their antiproliferative activity and their pro-apoptotic capacity are well documented and a small number of molecules of this class are currently used clinically for the treatment of BC. AEs also inhibit cell cycle progression and/or induce apoptosis in multiple myeloma (MM) cells. Encouraging preliminary results have been obtained with patients and on xenografts with MM, providing a rational basis for the clinical use of AEs. This review focuses on antioestrogen-mediated signalling for blocking targets involved in the cell cycle, survival and apoptosis in both BC and MM cells. Improvement in our understanding of the mechanisms underlying the relationships between these compounds and their targets should lead to more beneficial therapeutic strategies.

Synthesis and biological activity of simplified denoviose-coumarins related to novobiocin as potent inhibitors of heat-shock protein 90 (hsp90).

A new series of coumarin inhibitors of hsp90 lacking the noviose moiety as well as substituents on C-7 and C-8 positions of the aromatic ring was synthesised and their hsp90 inhibitory activity has been delineated: for example, their capacity to induce the degradation of client proteins and to inhibit estradiol-induced transcription in human breast cancer cells. In cell proliferation assay, the most active compound 5g was approximately 8 times more potent than the parent novobiocin natural compound.

Nanoparticles loaded with ferrocenyl tamoxifen derivatives for breast cancer treatment.

For the first time, two organometallic triphenylethylene compounds (Fc-diOH and DFO), with strong antiproliferative activity in breast cancer cells, but insoluble in biological fluids, were incorporated in two types of stealth nanoparticles (NP): PEG/PLA nanospheres (NS) and nanocapsules (NC). Their physicochemical parameters were measured (size, zeta potential, encapsulation and loading efficiency), and their biological activity was assessed. In vitro drug release after high dilution of loaded NPs was measured by estradiol binding competition in MELN cells. The influence of the encapsulated drugs on the cell cycle and apoptosis was studied by flow cytometry analyses. Notwithstanding potential drug adsorption at the NP surface, Fc-diOH and DFO were incorporated efficiently in NC and NS, which slowly released both compounds. They arrested the cell cycle in the S-phase and induced apoptosis, whose activity is increased by loaded NS. A decrease in their antiproliferative activity by the antioxidant alpha-tocopherol indicated that reactive oxygen species (ROS) may be involved. Therefore, nanosystems, containing for the first time a high load of anticancer organometallic triphenylethylenes, have been developed. Their small size and delayed drug release, combined with their enhanced apoptotic potential, are compatible with an increased persistence in the blood and a promising antitumour activity.

Estrogen receptor alpha and beta subtype expression and transactivation capacity are differentially affected by receptor-, hsp90- and immunophilin-ligands in human breast cancer cells.

In MCF-7 (estrogen receptor (ER)+) and in MDA-MB-231 (ER-) cells stably transfected with either estrogen receptor alpha (ERalpha) or beta (ERbeta) subtype (MDA-MB-231 stably transfected with the mouse ERalpha cDNA (MERA) and MDA-MB-231 stably transfected with the human ERbeta cDNA (HERB), respectively) N-term heat shock protein of 90kDa (hsp90) ligands (geldanamycin and radicicol) and C-term hsp90 ligands (novobiocin) decrease the basal and estradiol (E(2))-induced transcription activity of ER on an estrogen responsive element (ERE)-LUC reporter construct concomitantly with or 1h after E(2) treatment. All hsp90 ligands induced an E(2)- and MG132-inhibited decrease of both ER cell content. However, the kinetics of these degradations are slower than those induced by the selective estrogen receptor down-regulator RU 58668 (RU). This suggests that inhibition of the hsp90 ATPase activity targets both ERs to the 26S proteasome and that hsp90 interacts with both ER subtypes. Rapamycin (Rapa) and cyclosporin A (CsA), ligands of immunophilins FK506 binding protein (FKBP52) and cyclophilin of 40kDa (CYP40) interacting in separate ER-hsp90 complexes, both induced a proteasomal-mediated degradation of ERs but not of their cognate immunophilin. Moreover, they also decrease the E(2)-induced luciferase transcription but weaker than RU and hsp90 ligands. Fluorescence activated cell sorter (FACS) analysis revealed a blockade of cell progression by RU and 4-hydroxy-tamoxifen at the G(1) phase of the cell cycle and an induction of apoptosis in MCF-7 cells. Rapa and mainly CsA (but not FK506) and hsp90 ligands promote by their own apoptosis in MCF-7, in MERA, and in HERB cells and in MDA-MB-231 ER-null cells. These data suggest that (1) hsp90, as for all steroid receptors, acts as a molecular chaperone for ERbeta; (2) ER-ligands (except tamoxifen), hsp90- and immunophilin-ligands (except FK506) target the two ER subtypes to a proteasome-mediated proteolysis via different signalling pathways; (3) hsp90- and immunophilin-ligands Rapa and CsA, alone or in association with anti-estrogens such as RU, may constitute a potential therapeutic strategy for breast cancer treatment.