Modelling the impact of nucleolin expression level on the activity of F3 peptide-targeted pH-sensitive pegylated liposomes containing doxorubicin

Strategies targeting nucleolin have enabled a significant improvement in intracellular bioavailability of their encapsulated payloads. In this respect, assessment of the impact of target cell heterogeneity and nucleolin homology across species (structurally and functionally) is of major importance. This work also aimed at mathematically modelling the nucleolin expression levels at the cell membrane, binding and internalization of pH-sensitive pegylated liposomes encapsulating doxorubicin and functionalized with the nucleolin-binding F3 peptide (PEGASEMP), and resulting cytotoxicity against cancer cells from mouse, rat, canine, and human origin. Herein, it was shown that nucleolin expression levels were not a limitation on the continuous internalization of F3 peptide-targeted liposomes, despite the saturable nature of the binding mechanism. Modeling enabled the prediction of nucleolin-mediated total doxorubicin exposure provided by the experimental settings of the assessment of PEGASEMP's impact on cell death. The former increased proportionally with nucleolin-binding sites, a measure relevant for patient stratification. This pattern of variation was observed for the resulting cell death in nonsaturating conditions, depending on the cancer cell sensitivity to doxorubicin. This approach differs from standard determination of cytotoxic concentrations, which normally report values of incubation doses rather than the actual intracellular bioactive drug exposure. Importantly, in the context of development of nucleolin-based targeted drug delivery, the structural nucleolin homology (higher than 84%) and functional similarity across species presented herein, emphasized the potential to use toxicological data and other metrics from lower species to infer the dose for a first-in-human trial.

The Enhanced Efficacy of Intracellular Delivery of Doxorubicin/C6-Ceramide Combination Mediated by the F3 Peptide/Nucleolin System Is Supported by the Downregulation of the PI3K/Akt Pathway

Simple Summary

Targeted nanomedicine-based approaches that aim at the simultaneous delivery of synergistic drug combinations to multiple cellular populations are of high relevance for tackling heterogeneity on solid tumors. Considering that cancer stem cells (CSC) may originate from non-stem cancer cells, single-drug regimens targeting only one of these cell populations could enable tumors to evade treatments. As such, the identification of a common marker, such as nucleolin, might result in a therapeutic advantage. The results herein generated suggested a transversal role of nucleolin in the internalization of F3 peptide-targeted pegylated pH-sensitive liposomes into bulk ovarian cancer cells, including putative CSC-enriched ovarian cells. The intracellular delivery of a drug combination such as the one tested herein was relevant in the context of cell lines with higher intrinsic resistances to doxorubicin. The enhanced efficacy of the F3 peptide-targeted liposomal combination of doxorubicin/C6-ceramide was supported by the downregulation of the Akt pathway, within a specific range of basal level of expression.

Abstract

Targeting multiple cellular populations is of high therapeutic relevance for the tackling of solid tumors heterogeneity. Herein, the ability of pegylated and pH-sensitive liposomes, functionalized with the nucleolin-binding F3 peptide and containing doxorubicin (DXR)/C6-ceramide synergistic combination, to target, in vitro, ovarian cancer, including ovarian cancer stem cells (CSC), was assessed. The underlying molecular mechanism of action of the nucleolin-mediated intracellular delivery of C6-ceramide to cancer cells was also explored. The assessment of overexpression of surface nucleolin expression by flow cytometry was critical to dissipate differences identified by Western blot in membrane/cytoplasm of SKOV-3, OVCAR-3 and TOV-112D ovarian cancer cell lines. The former was in line with the significant extent of uptake into (bulk) ovarian cancer cells, relative to non-targeted and non-specific counterparts. This pattern of uptake was recapitulated with putative CSC-enriched ovarian SKOV-3 and OVCAR-3 sub-population (EpCAM^high/CD44^high). Co-encapsulation of DXR:C6-ceramide into F3 peptide-targeted liposomes improved cytotoxic activity relative to liposomes containing DXR alone, in an extent that depended on the intrinsic resistance to DXR and on the incubation time. The enhanced cytotoxicity of the targeted combination was mechanistically supported by the downregulation of PI3K/Akt pathway by C6-ceramide, only among the nucleolin-overexpressing cancer cells presenting a basal p-Akt/total Akt ratio lower than 1.

Cell surface Nucleolin represents a novel cellular target for neuroblastoma therapy

BACKGROUND

Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Nucleolin (NCL) is a protein overexpressed and partially localized on the cell surface of tumor cells of adult cancers. Little is known about NCL and pediatric tumors and nothing is reported about cell surface NCL and NB.

METHODS

NB cell lines, Schwannian stroma-poor NB tumors and bone marrow (BM)-infiltrating NB cells were evaluated for the expression of cell surface NCL by Flow Cytometry, Imaging Flow Cytometry and Immunohistochemistry analyses. The cytotoxic activity of doxorubicin (DXR)-loaded nanocarriers decorated with the NCL-recognizing F3 peptide (T-DXR) was evaluated in terms of inhibition of NB cell proliferation and induction of cell death in vitro, whereas metastatic and orthotopic animal models of NB were used to examine their in vivo anti-tumor potential.

RESULTS

NB cell lines, NB tumor cells (including patient-derived and Patient-Derived Xenografts-PDX) and 70% of BM-infiltrating NB cells show cell surface NCL expression. NCL staining was evident on both tumor and endothelial tumor cells in NB xenografts. F3 peptide-targeted nanoparticles, co-localizing with cell surface NCL, strongly associates with NB cells showing selective tumor cell internalization. T-DXR result significantly more effective, in terms of inhibition of cell proliferation and reduction of cell viability in vitro, and in terms of delay of tumor growth in all NB animal model tested, when compared to both control mice and those treated with the untargeted formulation.

CONCLUSIONS

Our findings demonstrate that NCL could represent an innovative therapeutic cellular target for NB.

Abstract 3622: Differential effect of liposomal C6-ceramide/doxorubicin targeted to nucleolin and conventional combinations against triple negative breast cancer stem cells

The interconversion between cancer stem cells (CSCs) and non-stem cancer cells (non-SCCs) in response to environmental stimulus, has urged the need to identify markers common to both cell sub-populations. This is the case of cell surface nucleolin, a target for drug delivery, offering the opportunity to target both cell populations as previously demonstrated (Fonseca, Biomaterials 2015). Herein, it is hypothesized that the intracellular delivery of the developed liposomal synergistic combination of doxorubicin (DXR) and the sphingolipid C6-ceramide (C6), functionalized with a nucleolin-binding peptide, [F3]L-DC6, will imbalance the CSC niche of triple-negative breast cancer (TNBC), relative to a clinically used combination of DXR and cisplatin (Cis). Cytotoxicity against (bulk) TNBC cell lines (MDA-MB-231, MDA-MB-468 and HS-578T) was assessed by the rezasurin assay. The impact over the putative CSCs population (ALDHhigh, as determined by the Aldefluor assay) was evaluated by flow cytometry. Moreover, assessment of the effect of each drug combination on the in vitro stemness properties of TNBC cells (the mRNA levels of pluripotency transcripts OCT4 and NANOG and mammosphere-forming capacity) was also performed. The intracellular delivery of the DXR:C6 (1:1 molar ratio) combination provided by the formulation targeted to nucleolin ([F3]L-DC6) enabled a significant increase in bulk cell death, compared with the counterpart single drug formulation. In fact, only the targeted liposomal DXR:C6 combination enabled a 90% death in the case of MDA-MB-231 cells, for an exposure as short as 4 h. This was in contrast with the lack cytotoxic benefit of the (non-liposomal) DXR:Cis combination over each drug alone, against each one of the TNBC cell lines used. Despite increasing concentrations of the DXR:Cis combination, enabled higher (bulk) cell death, the percentage of ALDHhigh viable cells increased by 1.5-fold relative to the untreated control, in the case of MDA-MB-468 cells. Interestingly, the opposite effect was observed for the DXR:C6 combination targeted to nucleolin, where increasing concentrations enabled higher (bulk) cell death, along with a 5-fold decrease of the percentage of viable ALDHhigh putative CSCs (relative to untreated control). These observations were concomitant with alterations of stemness properties favoring the latter. Overall, the enhanced efficacy of the synergistic DXR:C6 combination targeted to nucleolin, enables a significant decrease of the percentage of chemoresistant triple negative breast CSC, besides non-SCCs, in contrast to observations with clinically used drug combination. Thus, this novel strategy offers the potential to address tumor recurrence and drug resistance associated with CSC, in an unmet medical need as TNBC.

Citation Format: Ana F. Cruz, Nuno A. Fonseca, Nélio Gonçalves, Vera Moura, Sérgio Simões, João Nuno Moreira. Differential effect of liposomal C6-ceramide/doxorubicin targeted to nucleolin and conventional combinations against triple negative breast cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3622.

Abstract 2994: In vivo targeting of mesothelioma’s molecular signature with nanoparticle functionalized with nucleolin-binding peptide

Mesothelioma is a malignant tumor of the mesothelium, often associated with asbestos exposure, with an overall survival of only 8.8 months. A combination of cisplatin and pemetrexed has been used as an adjuvant treatment to surgical resection or in patients who have inoperable disease. This combination remains as the current standard of care, regardless the sub-type of mesothelioma, with only a 9% 5-year survival rate. Herein, it is hypothesized that a novel targeted treatment, based on a doxorubicin (DXR)-containing nanoparticle functionalized with the nucleolin-binding F3 peptide (named PEGASEMP), will have significant a therapeutic impact against the most aggressive subtype of mesothelioma (biphasic). The hypothesis relies on nucleolin deregulated overexpression in cancer and endothelial cells from tumor blood vessels. Human biphasic mesothelioma cells were stably transduced with luciferase-reporter gene, and orthotopically injected intrapleurally into female immunocompromised mice. Three weeks (Early Stage) and 4 weeks (Advanced Stage) after cell injection, animals were randomly allocated to different treatment groups: vehicle, PEGASEMP at 5.6 or 7 mg of DXR/kg alone (q7dx5w); cisplatin at 4.0 mg/kg alone or combined with PEGASEMP at 5.6 mg of DXR/kg (q7dx5w); and the standard of care, a combination of cisplatin at 4.0 mg/kg (q7dx5w) plus pemetrexed at 100.0 mg/kg (q2dx3x5w). Bioluminescence was monitored weekly with IVIS Spectrum In Vivo Imaging system. Differential gene expression upon PEGASEMP treatment of advanced stage tumors was also performed in comparison with non-treated animals using the GeneChip Human Transcriptome Array 2.0. In the early stage of development, PEGASEMP, at 7.0 mg/kg, inhibited tumor growth by 2,713-fold relative to standard of care, which translated into a 1223-fold decrease in tumor burden. At an advanced stage of tumor development, the combination of PEGASEMP and cisplatin enabled 107-fold tumor growth inhibition, enabling a 55-fold reduction in tumor burden, relative to standard of care. In both cases, no decrease of the body weight was observed. Furthermore, 75% (146) gene transcripts were found to be deregulated (while the remaining 25% were upregulated), involving the downregulation of cell division, including ontologies such as cell cycle or chromatin organization and assembly. Specifically, downregulation of topoisomerase 2, cyclin B1 or Ki67 transcripts, part of the described molecular signature of mesothelioma, was observed and was consistent with the mechanism of action of doxorubicin. Overall, the novel mechanism of action associated with PEGASEMP, enables a significant benefit in terms of efficacy and safety in the treatment of biphasic mesothelioma, as compared with the current standard of care, affecting the molecular signature of the disease and thus supporting future clinical evaluation.

Citation Format: Nuno A. Fonseca, Vera Moura, Fabiana Colelli, Daniela Pesce, Giacomo Signorino, Laura Focareta, Alessandra Fucci, Francesco Cardile, Claudio Pisano, Sérgio Simões, João Nuno Moreira. In vivo targeting of mesothelioma’s molecular signature with nanoparticle functionalized with nucleolin-binding peptide [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2994.

Anticancer activity and antibody-dependent cell-mediated cytotoxicity of novel anti-nucleolin antibodies

Nucleolin arises as a relevant target for cancer therapy, as it is overexpressed at the surface of cancer and angiogenic endothelial cells thus enabling a dual cellular targeting strategy. Immunotherapeutic strategies, albeit of proven therapeutic relevance, have been scarcely explored against this target. Therefore, this work aimed at engineering an anti-nucleolin VHH-based antibody capable of triggering anticancer immune responses. Herein, anti-nucleolin VHHs have been generated upon grafting F3 peptide-derived nucleolin-binding sequences onto a VHH CDR1 or CDR3. One of these nucleolin-binding CDR3-grafted VHH was subsequently fused to a human IgG1 Fc region, enabling a significant antibody-dependent cell-mediated cytotoxicity (ADCC). The generated anti-nucleolin VHH revealed increased binding and antiproliferative effects against cancer cells, relative to the parental VHH, while the VHH-Fc counterpart presented increased cytotoxicity relative to the corresponding VHH. This VHH-Fc also triggered an ADCC effect, in the nanomolar range, against a nucleolin-overexpressing cancer cell line. This effect was evidenced by a 2 or 1.7-fold increase of cell death, in the presence of PBMCs, relative to the parental VHH-Fc or the VHH counterpart, respectively. Overall, these formats represent the first anti-nucleolin VHHs and the first anti-nucleolin antibody with ADCC activity that have been successfully developed.

Targeting cancer stem cells and non-stem cancer cells: the potential of lipid-based nanoparticles

Background Cancer stem cells (CSCs) have been described as a relevant contributor to tumorigenicity, metastasis, tumor recurrence and drug resistance, making this cell population a relevant target in solid tumors.

METHODS

This has stimulated the development of different therapeutic strategies often targeting surface markers (CD44, epithelial cell adhesion molecule (EpCAM), aldehyde dehydrogenase (ALDH) and nucleolin) and/or signaling pathways that are aberrantly activated and contribute to CSCs proliferation and survival.

RESULTS

There are a variety of signaling pathways often involved in physiological processes of cell function that aberrantly regulate CSCs, including Notch, Hedgehog, Wnt, PI3K/Akt, JAK/STAT and Ras/ERK signaling pathways. The inhibition of these pathways usually depletes CSC population and increases tumor sensitivity to chemotherapy. However, the recognition of the potential of cells to interconvert in response to environmental stimulus, turned both CSCs and non-stem cancer cells into two relevant therapeutic targets. Therefore, the use of drug combinations is increasingly needed. These drugs with different mechanisms of action often characterized by distinct pharmacokinetics profiles and, as such, will present distinct biodistribution patterns, following systemic administration. To synchronize pharmacokinetics, one can encapsulate synergistic drug combinations into lipid-based nanoparticles, assuring tumor delivery of the selected drug ratio.

CONCLUSION

This review will focus on the multiple strategies to target CSCs, as well as on the potential of lipid-based nanoparticles to target both CSCs and non-stem cancer cells.

Metabolomics as a promising tool for early osteoarthritis diagnosis

Osteoarthritis (OA) is the main cause of disability worldwide, due to progressive articular cartilage loss and degeneration. According to recent research, OA is more than just a degenerative disease due to some metabolic components associated to its pathogenesis. However, no biomarker has been identified to detect this disease at early stages or to track its development. Metabolomics is an emerging field and has the potential to detect many metabolites in a single spectrum using high resolution nuclear magnetic resonance (NMR) techniques or mass spectrometry (MS). NMR is a reproducible and reliable non-destructive analytical method. On the other hand, MS has a lower detection limit and is more destructive, but it is more sensitive. NMR and MS are useful for biological fluids, such as urine, blood plasma, serum, or synovial fluid, and have been used for metabolic profiling in dogs, mice, sheep, and humans. Thus, many metabolites have been listed as possibly associated to OA pathogenesis. The goal of this review is to provide an overview of the studies in animal models and humans, regarding the use of metabolomics as a tool for early osteoarthritis diagnosis. The concept of osteoarthritis as a metabolic disease and the importance of detecting a biomarker for its early diagnosis are highlighted. Then, some studies in plasma and synovial tissues are shown, and finally the application of metabolomics in the evaluation of synovial fluid is described.

Abstract 2194: Synergistic cytotoxicity of targeted liposomes containing doxorubicin and C6-ceramide against nucleolin-overexpressing ovarian cancer cells is supported by the downregulation of the Akt pathway

The acknowledgment that cancer stem cells (CSC) may originate from non-stem cancer cells, interconverting through an EMT-mediated process has turned these distinct cell subpopulations into two relevant therapeutic targets. Moreover, the PI3K/AKT/mTOR pathway is essential to CSC proliferation and survival and it is often over activated in ovarian cancer. One of the strategies to target these different tumor cell populations, relies on the combination of conventional chemotherapeutic drugs (as tumor debulking agents, targeting non-stem cancer cells) with sphingolipids targeting CSC (at the level of PI3K/Akt/mTOR). Nucleolin overexpression has been demonstrated on the surface of both breast CSC and non-stem breast cancer cells (Fonseca NA, Biomaterials 2015) and endothelial cells from tumor blood vessels. The pH-sensitive lipid-based nanoparticle, functionalized with the nucleolin-binding F3 peptide, was recently modified to encapsulate a synergistic combination of a sphingolipid (C6-ceramide) and doxorubicin (DXR). Following the promising results in breast cancer, the aim of this work was to assess the therapeutic potential of this strategy against nucleolin-overexpressing ovarian cancer cell lines, as well as the underlying mechanism of action at the molecular level. A 12.9-fold increase of association of fluorescently-labelled F3 peptide-targeted liposomes ([F3]L), relative to the non-targeted counterparts, into (bulk) ovarian cancer cell lines (SKOV-3, OVCAR-3 and TOV-112D) was observed by flow cytometry. Importantly, a similar pattern of association by putative CSC enriched population (CD44high/EpCAMhigh) was also observed. These results corroborated the marked increase of cytotoxicity (assessed by the resazurin reduction viability assay) enabled by the targeted drug combinations, relative to [F3]L containing only DXR. In fact, the targeted drug combination enabled a 90% death of SKOV-3 cancer cells, following an 8 h incubation, a level of cell killing not achieved by the counterpart containing only DXR. Against the OVCAR-3 and TOV-112D cell lines, the IC90 of the targeted drug combination, following 1 h of incubation, was 2-fold lower than the one resulting from the incubation with [F3]L containing only DXR. In addition, the effect of nucleolin-mediated intracellular delivery of C6-ceramide at the p-Akt protein levels was further discriminated by western blot analysis in SKOV-3 cells. The observed 3.2-fold downregulation of p-Akt levels supported the C6-ceramide-mediated improved cytotoxicity of the drug combination. Overall, these results pointed out the enhanced efficacy of targeted synergistic drug combinations against ovarian cancer, due to the capability to target nucleolin-overexpressing cancer cells and further inhibit the Akt pathway.

Citation Format: Ana Filipa Cruz, Nuno André Fonseca, Susana F. Sampaio, Vera Moura, Ramiro D. Almeida, Sérgio Simões, João Nuno Moreira. Synergistic cytotoxicity of targeted liposomes containing doxorubicin and C6-ceramide against nucleolin-overexpressing ovarian cancer cells is supported by the downregulation of the Akt pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2194. doi:10.1158/1538-7445.AM2017-2194

Abstract 5155: Targeting nucleolin with doxorubicin-containing nanoparticle induces a significant tumor growth inhibition in an orthotopic animal model of standard of care-resistant mesothelioma

Mesothelioma is a malignant tumor of the mesothelium, the thin lining of the surface of the body cavities and the organs within, and is often associated with asbestos exposure. It has a poor prognosis, with a mean overall survival of 8.8 months. Chemotherapy has been used for malignant pleural mesothelioma as an adjuvant treatment after surgical resection (often palliative) or in patients who have inoperable disease. A combination of cisplatin and pemetrexed remains as the current standard of care, with only a 9% 5-year survival rate. Herein, a novel targeted treatment for mesothelioma, based on a doxorubicin (DXR)-containing nanoparticle functionalized with the nucleolin-binding F3 peptide (named PEGASEMP), is proposed. It relies on nucleolin deregulated overexpression in cancer cells and the tumor microenvironment (endothelial cells from tumor blood vessels). Studies were performed in an orthotopic model of human mesothelioma. Mesothelioma cells harvested from a patient with disease progression who undergone chemotherapy, were stably transduced with luciferase-reporter gene, and orthotopically injected intrapleurally into female immunocompromised mice. Animals were randomly allocated to different treatment groups: vehicle, peptide-targeted DXR-containing nanoparticle (PEGASEMP) at 5.6 or 7 mg of DXR/kg alone (q7dx5w); cisplatin at 4.0 mg/kg alone or combined with PEGASEMP at 5.6 mg of DXR/kg (q7dx5w). A control group administered with the standard of care, a combination of cisplatin at 4.0 mg/kg (q7dx5w) plus pemetrexed at 100.0 mg/kg (q2dx3x5w) was also included. Bioluminescence was monitored weekly with live imaging using IVIS Spectrum In Vivo Imaging system. Peptide-targeted DXR-containing nanoparticle at 7.0 mg/kg enabled a tumor growth inhibition, by the end of the treatment, that was 183-fold higher than the standard of care. Moreover, treatment with DXR-containing nanoparticle targeting nucleolin, either at 5.6 or 7.0 mg/kg, enabled a 10- or 66-fold reduction of tumor burden, respectively, relative to non-treated mice. Conversely, treatment with the standard of care did not show any effect on tumor growth inhibition (being similar to the group injected with vehicle) nor on tumor burden. Importantly, DXR-containing nanoparticle targeting nucleolin, at the highest tested dose, enabled a marked decreased of the incidence of tumor infiltration into the chest cavity, as well as of the presence of severe lung lesions, as compared with the standard of care (57.1% versus 100% and 14.3% versus 50%, respectively). Overall, the novel mechanism of action associated with DXR-containing nanoparticle targeting nucleolin, enables a significant benefit in terms of efficacy (and safety) in the treatment of mesothelioma, as compared with the current standard of care, thus supporting future clinical evaluation.

Citation Format: Nuno André Fonseca, Vera Moura, Fabiana Colelli, Daniela Pesce, Francesco Cardile, Claudio Pisano, Sérgio Simões, João Nuno Moreira. Targeting nucleolin with doxorubicin-containing nanoparticle induces a significant tumor growth inhibition in an orthotopic animal model of standard of care-resistant mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5155. doi:10.1158/1538-7445.AM2017-5155

The cancer stem cell phenotype as a determinant factor of the heterotypic nature of breast tumors

Gathering evidence supports the existence of a population of cells with stem-like characteristics, named cancer stem cells (CSC), which is involved not only in tumor recurrence but also in tumorigenicity, metastization and drug resistance. Several markers have been used to identify putative CSC sub-populations in different cancers. Notwithstanding, it has been acknowledged that breast CSC may originate from non-stem cancer cells (non-SCC), interconverting through an epithelial-to-mesenchymal transition-mediated process, and presenting several deregulated canonical and developmental signaling pathways. These support the heterogeneity that, directly or indirectly, influences fundamental biological features supporting breast tumor development. Accordingly, CSC have increasingly become highly relevant cellular targets. In this review, we will address the stemness concept in cancer, setting the perspective on CSC and their origin, by exploring their relation and regulation within the tumor microenvironment, in the context of emerging therapeutic targets. Within this framework, we will discuss nucleolin, a protein that has been associated with angiogenesis and, more recently, with the stemness phenotype, becoming a common denominator between CSC and non-SCC for multicellular targeting.

Inoculated Cell Density as a Determinant Factor of the Growth Dynamics and Metastatic Efficiency of a Breast Cancer Murine Model

4T1 metastatic breast cancer model have been widely used to study stage IV human breast cancer. However, the frequent inoculation of a large number of cells, gives rise to fast growing tumors, as well as to a surprisingly low metastatic take rate. The present work aimed at establishing the conditions enabling high metastatic take rate of the triple-negative murine 4T1 syngeneic breast cancer model. An 87% 4T1 tumor incidence was observed when as few as 500 cancer cells were implanted. 4T1 cancer cells colonized primarily the lungs with 100% efficiency, and distant lesions were also commonly identified in the mesentery and pancreas. The drastic reduction of the number of inoculated cells resulted in increased tumor doubling times and decreased specific growth rates, following a Gompertzian tumor expansion. The established conditions for the 4T1 mouse model were further validated in a therapeutic study with peguilated liposomal doxorubicin, in clinical used in the setting of metastatic breast cancer. Inoculated cell density was proven to be a key methodological aspect towards the reproducible development of macrometastases in the 4T1 mouse model and a more reliable pre-clinical assessment of antimetastatic therapies.

Nucleolin overexpression in breast cancer cell sub-populations with different stem-like phenotype enables targeted intracellular delivery of synergistic drug combination

Breast cancer stem cells (CSC) are thought responsible for tumor growth and relapse, metastization and active evasion to standard chemotherapy. The recognition that CSC may originate from non-stem cancer cells (non-SCC) through plastic epithelial-to-mesenchymal transition turned these into relevant cell targets. Of crucial importance for successful therapeutic intervention is the identification of surface receptors overexpressed in both CSC and non-SCC. Cell surface nucleolin has been described as overexpressed in cancer cells as well as a tumor angiogenic marker. Herein we have addressed the questions on whether nucleolin was a common receptor among breast CSC and non-SCC and whether it could be exploited for targeting purposes. Liposomes functionalized with the nucleolin-binding F3 peptide, targeted simultaneously, nucleolin-overexpressing putative breast CSC and non-SCC, which was paralleled by OCT4 and NANOG mRNA levels in cells from triple negative breast cancer (TNBC) origin. In murine embryonic stem cells, both nucleolin mRNA levels and F3 peptide-targeted liposomes cellular association were dependent on the stemness status. An in vivo tumorigenic assay suggested that surface nucleolin overexpression per se, could be associated with the identification of highly tumorigenic TNBC cells. This proposed link between nucleolin expression and the stem-like phenotype in TNBC, enabled 100% cell death mediated by F3 peptide-targeted synergistic drug combination, suggesting the potential to abrogate the plasticity and adaptability associated with CSC and non-SCC. Ultimately, nucleolin-specific therapeutic tools capable of simultaneous debulk multiple cellular compartments of the tumor microenvironment may pave the way towards a specific treatment for TNBC patient care.

Abstract 4521: A novel targeted triggered release nanoparticle against cancer cells of diverse histological origin

The paradigm of cancer treatment has changed substantially over the last decade. The discovery of new therapeutic targets within the tumor cell and the recognition of the interdependence with the tumor microenvironment have been the basis of such changes. However, no common ground was yet found for the treatment of cancer within its diverse histological origin. Conventional therapy against human canc¬er, relying on the use of drugs that do not differentiate between cancer and normal cells, is progressively giving room to novel therapeutic strategies. Specificity became mandatory for treatment effectiveness and target selection one of the main priorities. In this scenario, delivery systems rise as promising approaches, for the reason they can improve pharmacokinetic features of anticancer drugs and efficiently address a particular payload to a selected target, namely through exploitation of high specificity and affinity between cell-surface receptors and targeting ligands coupled at their surface.

We evidence the overexpression of a target cell surface receptor (nucleolin) in several cancer cell lines of diverse histological origins: breast (hormone-dependent and triple negative subtypes), colon, prostate and small cell and non-small cell lung cancer. We demonstrate the ability of the nucleolin receptor to specifically internalize a F3-targeted sterically stabilized lipid-based formulation. Moreover, we show that the unique combination of targeting specificity and intracellular triggered release of a therapeutic agent, doxorubicin, results in enhanced cytotoxic activity in those specific cell lines, when compared to the non-targeted counterpart.

Active accumulation of the targeted nanoparticle into human orthotopic tumors, implanted in the mammary fat pad of nude mice, was registered for a time-point as short as 4 h, reaching 48% of the injected dose/g of tissue. Twenty-four hours post-injection accumulation in the tumor tissue was 33-fold higher than the non-targeted counterpart. In mice treated with the targeted nanoparticle containing doxorubicin, significant decrease of the tumor viable rim area and microvascular density, as well as limited invasion to surrounding healthy tissues were observed (as opposed to other tested controls). Moreover, the clinical potential of such strategy was demonstrated by the successful specific cellular association by breast cancer cells harvested from tumors of patients submitted to mastectomy.

Overall, we provide evidence of a nanoparticle with specificity to cancer cells of diverse histological origins and proven therapeutic efficacy in an animal model of breast cancer, which may be a breakthrough in the development of anticancer therapies, especially when considering cancer cell heterogeneity.

Citation Format: Vera Moura, Manuela Lacerda, Paulo Figueiredo, Maria L. Corvo, Maria M E Cruz, Raquel Soares, Sérgio Simões, João Moreira. A novel targeted triggered release nanoparticle against cancer cells of diverse histological origin. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4521. doi:10.1158/1538-7445.AM2013-4521

Toward a siRNA-containing nanoparticle targeted to breast cancer cells and the tumor microenvironment

The present work aimed at designing a lipid-based nanocarrier for siRNA delivery toward two cell sub-populations within breast tumors, the cancer and the endothelial cells from angiogenic tumor blood vessels. To achieve such goal, the F3 peptide, which is specifically internalized by nucleolin overexpressed on both those sub-populations, was used as a targeting moiety. The developed F3-targeted stable nucleic acid lipid particles presented adequate features for systemic administration. In addition, the attachment of the F3 peptide onto the liposomal surface enabled an internalization by both cancer and endothelial cells from angiogenic blood vessels that was significantly higher than the one observed with non-cancer cells. Sequence-specific downregulation of enhanced green fluorescent protein (eGFP) in eGFP-overexpressing human cancer cell lines, both at the protein and mRNA levels, was further observed upon delivery of anti-eGFP siRNA by F3-targeted liposomes, in contrast with the non-targeted counterpart. This effect was highly dependent on the content of poly(ethylene glycol) (PEG), as evidenced by the co-localization studies between the siRNA and the lysosomes. Overall, the present work represents an important contribution toward a nanoparticle with multi-targeting capabilities in breast cancer, both at the cellular and molecular level.

Lipid-based nanoparticles for siRNA delivery in cancer therapy: paradigms and challenges

RNA interference (RNAi) is a specific gene-silencing mechanism that can be mediated by the delivery of chemical synthesized small-interfering RNA (siRNA). RNAi might constitute a novel therapeutic approach for cancer treatment because researchers can easily design siRNA molecules to inhibit, specifically and potently, the expression of any protein involved in tumor initiation and progression. Despite all the potential of siRNA as a novel class of drugs, the limited cellular uptake, low biological stability, and unfavorable pharmacokinetics of siRNAs have limited their application in the clinic. Indeed, blood nucleases easily degrade naked siRNAs, and the kidneys rapidly eliminate these molecules. Furthermore, at the level of target cells, the negative charge and hydrophilicity of siRNAs strongly impair their cellular internalization. Therefore, the translation of siRNA to the clinical setting is highly dependent on the development of an appropriate delivery system, able to ameliorate siRNA pharmacokinetic and biodistribution properties. In this regard, major advances have been achieved with lipid-based nanocarriers sterically stabilized by poly(ethylene glycol) (PEG), such as the stabilized nucleic acid lipid particles (SNALP). However, PEG has not solved all the major problems associated with siRNA delivery. In this Account, the major problems associated with PEGylated lipid-based nanoparticles, and the different strategies to overcome them are discussed. Although PEG has revolutionized the field of nanocarriers, cumulative experience has revealed that upon repeated administration, PEGylated liposomes lose their ability to circulate over long periods in the bloodstream, a phenomenon known as accelerated blood clearance. In addition, PEGylation impairs the internalization of the siRNA into the target cell and its subsequent escape from the endocytic pathway, which reduces biological activity. An interesting approach to overcome such limitations relies on the design of novel exchangeable PEG-derivatized lipids. After systemic administration, these lipids can be released from the nanoparticle surface. Moreover, the design and synthesis of novel cationic lipids that are more fusogenic and the use of internalizing targeting ligands have contributed to the emergence of novel lipid-based nanoparticles with remarkable transfection efficiency.

Targeted and intracellular triggered delivery of therapeutics to cancer cells and the tumor microenvironment: impact on the treatment of breast cancer

Limiting tumor invasion to the surrounding healthy tissues has proven to be clinically relevant for anticancer treatment options. We have demonstrated that, within a solid tumor, it is possible to achieve such a goal with the same nanoparticle by intracellular and triggered targeted drug delivery to more than one cell population. We have identified the nucleolin receptor in endothelial and cancer cells in tissue samples from breast cancer patients, which enabled the design of a F3-peptide-targeted sterically stabilized pH-sensitive liposome. The clinical potential of such strategy was demonstrated by the successful specific cellular association by breast cancer cells harvested from tumors of patients submitted to mastectomy. In vitro, the nanoparticle targeted the nucleolin receptor on a cell and ligand-specific manner and improved cytotoxicity of doxorubicin (used as a model drug) towards breast cancer and endothelial cells by 177- and 162-fold, respectively, relative to the commercially available non-targeted non-pH-sensitive liposomes. Moreover, active accumulation of F3-targeted pH-sensitive liposomes into human orthotopic tumors, implanted in the mammary fat pad of nude mice, was registered for a time point as short as 4 h, reaching 48% of the injected dose/g of tissue. Twenty-four hours post-injection the accumulation of the dual-targeted pH-sensitive nanoparticle in the tumor tissue was 33-fold higher than the non-targeted non-pH-sensitive counterpart. In mice treated with the developed targeted nanoparticle significant decrease of the tumor viable rim area and microvascular density, as well as limited invasion to surrounding healthy tissues were observed (as opposed to other tested controls), which may increase the probability of tumors falling in the category of "negative margins" with reduced risk of relapse.

Molecular analysis of CYP21A2 can optimize the follow-up of positive results in newborn screening for congenital adrenal hyperplasia

Neonatal screening for congenital adrenal hyperplasia (CAH) is useful in diagnosing salt wasting form (SW). However, there are difficulties in interpreting positive results in asymptomatic newborns. The main objective is to analyze genotyping as a confirmatory test in children with neonatal positive results. Patients comprised 23 CAH children and 19 asymptomatic infants with persistently elevated 17-hydroxyprogesterone (17OHP) levels. CYP21A2 gene was sequenced and genotypes were grouped according to the enzymatic activity of the less severe allele: A1 null, A2 < 2%, B 3-7%, C > 20%. Twenty-one children with neonatal symptoms and/or 17OHP levels > 80 ng/ml carried A genotypes, except two virilized girls (17OHP < 50 ng/ml) without CAH genotypes. Patients carrying SW genotypes (A1, A2) and low serum sodium levels presented with neonatal 17OHP > 200 ng/ml. Three asymptomatic boys carried simple virilizing genotypes (A2 and B): in two, the symptoms began at 18 months; another two asymptomatic boys had nonclassical genotypes (C). The remaining 14 patients did not present CAH genotypes, and their 17OHP levels were normalized by 14 months of age. Molecular analysis is useful as a confirmatory test of CAH, mainly in boys. It can predict clinical course, identify false-positives and help distinguish between clinical forms of CAH.

Non-viral lipid-based nanoparticles for targeted cancer systemic gene silencing

New molecular biology techniques have uncovered the hidden role of genes in cancer. Identification of activated oncogenes, as fundamental genetic differences relative to normal cells, has made it possible to consider such genes as targets for antitumor therapy, namely by applying gene silencing strategies. In this regard, antisense oligonucleotides or small interfering RNAs, constitute promising therapeutic tools. The widespread clinical application of such molecules as modulators of gene expression, is still dependent on several aspects that limit their bioavailability, including: enhanced biological stability, favourable pharmacokinetics, enhanced tumor cell uptake and, consequently, efficient targeted delivery. One of the most promising strategies to overcome the barriers faced by gene silencing molecules, upon systemic administration, involves the use of lipid-based nanoparticles. The first part of this review aims at providing the reader with the molecular mechanism of action of the most important gene silencing molecules used in anticancer therapy. The primary obstacle for translating gene silencing technology from an effective research tool into a feasible therapeutic strategy remains its efficient delivery to the targeted cell type in vivo. Therefore, an overview of different lipid-based strategies for nucleic acid delivery will be presented on the second part. As we learn more about the pharmacokinetics and pharmacodynamics of the carrier and/or of the gene silencing molecules, it will be possible to further improve the delivery strategy that likely in the future will lead to the ideal non-viral particle for targeted cancer systemic gene silencing.

Ageing and Toll-like receptor expression by innate immune cells in chronic human schistosomiasis

There has been no systematic study of the immune response of individuals aged over 60 years living in Schistosomiasis mansoni-endemic areas, although senescence is reportedly associated with susceptibility to infection and progressive decline in immune function. We have shown previously, in two endemic areas in Minas Gerais, Brazil, that the frequency of individuals aged over 60 years with chronic schistosomiasis is no longer negligible. Moreover, several elderly individuals who have always lived in these endemic areas stay protected from infection. An important question for studies of ageing and disease control in developing countries is which differences in the immunological profile of these negatively tested (non-infected) individuals can account for their resistance to either infection or reinfection. We show, in the present study, that non-infected (negative) elderly individuals develop innate immune mechanisms of protection that replace the age-associated decline in T cell function. Non-infected elderly individuals from endemic areas of schistosome infection present an increase in the frequency of the natural killer (NK) CD56(low) subset of NK cells expressing Toll-like receptors (TLR)-1, -2, -3 and -4 as determined by flow cytometry analysis. In addition, the proportion of dendritic cells expressing TLR-1 is elevated as well as the frequency of monocytes expressing TLR-1 and -4. These results suggest that TLR expression by cells of the innate immune system may be related to the negative status of infection in some elderly individuals who are constantly exposed to S. mansoni. Developing mechanisms of protection from infection may represent a biomarker for healthy ageing in this population.