The role of folate receptor alpha in cancer development, progression and treatment: cause, consequence or innocent bystander?

Hybrid folic acid-conjugated gold nanorods-loaded human serum albumin nanoparticles for simultaneous photothermal and chemotherapeutic therapy

Hybrid nanoparticles containing both structural and functional nanocomponents might result in higher success and increased quality of life for patients suffering a disease such as cancer. In this study, we combine chemotherapy of conventional drug doxorubicin (Dox) with gold nanorods (AuNR) for photothermal therapy using multifunctional human serum albumin nanoparticles (HSA NP's) fabricated via desolvation technique with high efficiency. Folic acid (FA) was conjugated to HSA NP's trough an amidation via carbodiimide reaction for a more specific nanoplataform to HeLa cancer cells. The loading efficiency of Dox into AuNR loaded-HSA NP reached up to 2 μg Dox/mg HSA. The HSA-AuNR-Dox NP experienced photothermal heating varying laser potency (1, 0.5 and 0.2 W); reaching the bulk particle solution an increment of 16, 8 and 6 °C after 10 min of near-IR laser exposure respectively. When HeLa cells were treated with this multifunctional nanoplataform containing only AuNR, cancer cells experienced 96% cell viability without irradiation and 55% cell viability after just one irradiation session. When Dox is present in the nanoplataform, viability were 60% and 24% for non-irradiated and irradiated nanoplataforms, respectively. This study demonstrates that HSA-AuNR-Dox nanoparticles are suitable systems allowing a synergic chemo and phothothermal therapy.

Identification of a peptide for folate receptor alpha by phage display and its tumor targeting activity in ovary cancer xenograft

The expression level of folate receptor alpha (FRα) is located highly rate in ovarian cancer though it is remained absent in normal tissues. This highly tumor restricted expression profile makes FRα a promising target for tumor therapy and diagnosis. In this research we report a FRα binding peptide C7(Met-His-Thr-Ala-Pro-Gly-Trp-Gly-Tyr-Arg-Leu-Ser) discovered by phage display and this peptide showed specific binding to FRα expressing cells by cell ELISA and flow cytometry. Tumor targeting ability of C7 was proved in vivo by both phage homing experiment and fluorescence imaging. C7 can be internalized by SKOV3 cells and its affinity to FRα was determined by MST. The molecular recognition was revealed by structure modeling, suggesting its binding mode with FRα.

Folate receptor-targeted 19 F MR molecular imaging and proliferation evaluation of lung cancer

BACKGROUND

Folate receptors (FRs) hold great potential as important diagnostic and prognostic biological marker for cancer.

PURPOSE

To assess the targeted capability of the FR-targeted perfluorocarbon (PFC) nanoparticles and to assess in vivo the relationship between FR expression and tumor proliferation with fluorine-19 (¹⁹ F) MR molecular imaging.

STUDY TYPE

Prospective animal cancer model.

ANIMAL MODEL

H460 (n = 14) and A549 (n = 14) nude mice subcutaneous tumor models.

FIELD STRENGTH

9.4T, ¹ H and ¹⁹ F RARE sequences.

ASSESSMENT

Intracellular uptake of the PFC nanoparticles was tested in H460 and A549 cell lines. ¹⁹ F MRI of H460 and A549 subcutaneous tumors was performed following intravenous injection of PFC nanoparticles. The concentration of PFC in tumors were compared. 3'-Deoxy-3'-¹⁸ F-fluorothymidine (¹⁸ F-FLT) positron emission tomography / computed tomography (PET/CT) imaging, Ki-67, and proliferating cell nuclear antigen (PCNA) staining were performed to confirm tumor proliferation.

STATISTICAL TESTS

One-way or two-way analysis of variance. P < 0.05 was considered a significant difference.

RESULTS

The diameter of the FR-targeted nanoparticles was 108.8 ± 0.56 nm, and the zeta potential was -58.4 ± 10.8 mV. H460 cells incubated with FR-targeted nanoparticles showed ∼59.87 ± 3.91% nanoparticles-labeled, which is significantly higher than the other groups (P < 0.001). The PFC concentration in H460 tumors after injection with FR-targeted nanoparticles was 4.64 ± 1.21, 8.04 ± 1.38, and 9.16 ± 2.56 mmol/L at 8 hours, 24 hours, and 48 hours, respectively (P < 0.05 compared to others). The ratio of ¹⁸ F-FLT uptake for H460 and A549 tumors was 3.32 ± 0.17 and 1.48 ± 0.09 (P < 0.05), and there was more Ki-67 and PCNA in H460 tumor than A549. DATA CONCLUSION: ¹⁹ F MRI with FR-targeted PFC nanoparticles can be used in differentiating of FR-positive and FR-negative tumors, and further, in evaluation of the two cancer models proliferation.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1617-1625.

A fusion-protein approach enabling mammalian cell production of tumor targeting protein domains for therapeutic development

A single chain Fv fragment (scFv) is a fusion of the variable regions of heavy (VH ) and light (VL ) chains of immunoglobulins. They are important elements of chimeric antigen receptors for cancer therapy. We sought to produce a panel of 16 extracellular protein domains of tumor markers for use in scFv yeast library screenings. A series of vectors comprising various combinations of expression elements was made, but expression was unpredictable and more than half of the protein domains could not be produced using any of the constructs. Here we describe a novel fusion expression system based on mouse TEM7 (tumor endothelial marker 7), which could facilitate protein expression. With this approach we could produce all but one of the tumor marker domains that could not otherwise be expressed. In addition, we demonstrated that the tumor associated antigen hFZD10 produced as a fusion protein with mTEM7 could be used to enrich scFv antibodies from a yeast display library. Collectively our study demonstrates the potential of specific fusion proteins based on mTEM7 in enabling mammalian cell production of tumor targeting protein domains for therapeutic development.

Reversal of drug resistance by planetary ball milled (PBM) nanoparticle loaded with resveratrol and docetaxel in prostate cancer

The folate receptor (FR) is a valued target that is highly expressed in various cancers, which will expedite the development of ligand-receptor binding based cancer therapeutics. In the present investigation, through tissue microarray analysis, we report higher levels of folate receptor expression in prostate cancer (PCa) tissue derived from patients, which were minimal in normal tissue. For folate-receptor based targeted therapy of PCa, we generated novel planetary ball milled (PBM) nanoparticles (NPs) encapsulated with resveratrol (RES), and in combination with docetaxel (DTX) and conjugated with folic acid (FA) on the surface. The cytotoxic effect of FA-conjugated DTX-nanoparticles was found effectual that reduced the concentration of free drug (DTX) to 28 times. Flow cytometry analysis showed a significant increase in the number of apoptotic cells by 30.92% and 65.9% in the FA-conjugated RES and in combination with DTX nanoparticle formulation respectively. However, only 8.9% apoptotic cells were found with control (empty NP). The expressions of NF-kB p65, COX-2, pro (BAX, BAK) and anti-apoptotic (BCL-2, BCL-XL) genes were significantly reduced after treatment with FA-RES + DTX-NP. In addition, the FA-conjugated DTX formulation exhibited additional cytotoxic effects with the down-regulation of survivin and an increased expression of Cleaved Caspase-3 in PCa cells. Further, we observed that treating DTX resistant PCa cells with FA-RES + DTX-NP exhibited a reversal of the ABC-transporter markers thereby limiting the multidrug resistance phenotype of the cancer cells. Our results strongly suggested that FA conjugated nanoparticle drugs acted as effective inhibitors of drug efflux that effectually enhances the intracellular concentration of the drug to exhibit their cytotoxic effect.

A pre-protective strategy for precise tumor targeting and efficient photodynamic therapy with a switchable DNA/upconversion nanocomposite

Tumor-specific targeting based on folic acid (FA) is one of the most common and significant approaches in cancer therapy. However, the expression of folate receptors (FRs) in normal tissues will lead to unexpected targeting and unsatisfactory therapeutic effect. To address this issue, we develop a pre-protective strategy for precise tumor targeting and efficient photodynamic therapy (PDT) using a switchable DNA/upconversion nanocomposite, which can be triggered in the acidic tumor microenvironment. The DNA/upconversion nanocomposite is composed of polyacrylic acid (PAA) coated upconversion nanoparticles (UCNPs), the surface of which is modified using FA and chlorin e6 (Ce6) functionalized DNA sequences with different lengths. Initially, FA on the shorter DNA was protected by a longer DNA to prevent the bonding to FRs on normal cells. Once reaching the acidic tumor microenvironment, C base-rich longer DNA forms a C-quadruplex, resulting in the exposure of the FA groups and the bonding of FA and FRs on cancer cell membranes to achieve precise targeting. Simultaneously, the photosensitizer chlorin e6 (Ce6) gets close to the surface of UCNPs, enabling the excitation of Ce6 to generate singlet oxygen (1O2) under near infrared light via Förster resonance energy transfer (FRET). In vivo experiments indicated that higher tumor targeting efficiency was achieved and the tumor growth was greatly inhibited through the pre-protective strategy.

Prospects of chimeric antigen receptor T cell therapy in ovarian cancer

Despite advances in various chemotherapy regimens, current therapeutic options are limited for ovarian cancer patients. Immunotherapy provides a promising and novel treatment option for ovarian cancer. Recently, chimeric antigen receptor (CAR) T cell therapy has shown promising results in hematological tumors and current research is going on in various solid tumors like ovarian cancer. CAR T cells are genetically engineered T cells with major histocompatibility complex-independent, tumor-specific, immune-mediated cytolytic actions against cancer cells. Initial studies of CAR T cell therapy have shown promising results in ovarian cancer, but there are some obstacles like impaired T cell trafficking, lack of antigenic targets, cytokine release syndrome and most important immunosuppressive tumor microenvironment. Optimization of design, improving tumor microenvironment and combinations with other therapies may help us in improving CAR T cell efficacy. In this review article, we highlight the current knowledge regarding CAR T cell therapy in ovarian cancer. We have discussed basic functioning of CAR T cells, their rationale and clinical outcome in ovarian cancer with limitations.

In silico characterization of functional single nucleotide polymorphisms of folate pathway genes

Folate metabolism genes are pivotal to critical biological processes and are related to several conditions, including developmental, cognitive, and cardiovascular anomalies. A systematic catalog of genetic polymorphisms in protein coding regions, regulatory transcription factor binding sites, and miRNA binding sites associated with folate pathway genes may contribute to personalized medicine. We performed a comprehensive computational survey of single nucleotide polymorphisms (SNPs) of folate pathway genes to highlight functional polymorphisms in the coding region, transcription factor binding sites, and miRNAs binding sites. Folate pathway genes were searched through PubMed and Kyoto Encyclopedia of Genes and Genomes pathway databases. SNPs were identified and characterized using the University of California, Santa Cruz genome browser and SNPnexus tool. Functional characterization of nonsynonymous SNPs (nsSNPS) was performed using bioinformatics tools, and common deleterious nsSNPs were identified. We identified 48 genes of folate pathway containing 287 SNPs in the coding regions. Out of these SNPs, rs5742905, rs45511401, and rs1801133 were predicted to be deleterious through four different bioinformatics tools. Three-dimensional structures of two proteins with and without deleterious nsSNPs were predicted by SWISSPDB viewer and SuperPose. Besides, a total of 237 SNPs was identified in transcription factor binding sites using the Genomatix software suite and six miRNA target site SNPs using miRNASNP. This systematic and extensive in silico analysis of functional SNPs of folate pathway may provide a foundation for future targeted mechanistic, structure-function, and genetic epidemiological studies.

Functionalized rare earth-doped nanoparticles for breast cancer nanodiagnostic using fluorescence and CT imaging

Background

Breast cancer is the second leading cause of cancer death among women and represents 14% of death in women around the world. The standard diagnosis method for breast tumor is mammography, which is often related with false-negative results leading to therapeutic delays and contributing indirectly to the development of metastasis. Therefore, the development of new tools that can detect breast cancer is an urgent need to reduce mortality in women. Here, we have developed Gd₂O₃:Eu³⁺ nanoparticles functionalized with folic acid (FA), for breast cancer detection.

Results

Gd₂O₃:Eu³⁺ nanoparticles were synthesized by sucrose assisted combustion synthesis and functionalized with FA using EDC-NHS coupling. The FA-conjugated Gd₂O₃:Eu³⁺ nanoparticles exhibit strong red emission at 613 nm with a quantum yield of ~ 35%. In vitro cytotoxicity studies demonstrated that the nanoparticles had a negligible cytotoxic effect on normal 293T and T-47D breast cancer cells. Cellular uptake analysis showed significantly higher internalization of FA-conjugated RE nanoparticles into T-47D cells (Folr^hi) compared to MDA-MB-231 breast cancer cells (Folr^lo). In vivo confocal and CT imaging studies indicated that FA-conjugated Gd₂O₃:Eu³⁺ nanoparticles accumulated more efficiently in T-47D tumor xenograft compared to the MDA-MB-231 tumor. Moreover, we found that FA-conjugated Gd₂O₃:Eu³⁺ nanoparticles were well tolerated at high doses (300 mg/kg) in CD1 mice after an intravenous injection. Thus, FA-conjugated Gd₂O₃:Eu³⁺ nanoparticles have great potential to detect breast cancer.

Conclusions

Our findings provide significant evidence that could permit the future clinical application of FA-conjugated Gd₂O₃:Eu³⁺ nanoparticles alone or in combination with the current detection methods to increase its sensitivity and precision.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0359-9) contains supplementary material, which is available to authorized users.

Expression status of folate receptor alpha is a predictor of survival in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has one of the poorest prognosis among malignancies. Thus, the identification of markers useful in developing innovative diagnostic and therapeutic methods is an imperative need. Folate receptor alpha (FRα) has been associated with prognosis in several cancers and has served as a target of novel anti-tumor therapies. However, FRα expression in PDAC and its correlation with the clinical course of the disease has not been thoroughly investigated. In this study, we analyzed FRα expression in 140 PDAC specimens and 7 PDAC cell lines in order to define the significance of FRα expression in PDAC and its potential role as a target for immunotherapy. Immunohistochemical analysis demonstrated that FRα expression intensity was low, intermediate and high in 22(16%), 73(52%) and 45(32%) PDACs, respectively. The staining was located in both membrane and cytoplasm in most cases (123, 88%). Lower FRα expression was associated with cigarette smoking (p<0.001), alcohol consumption (p<0.001), and lymphovascular invasion (p=0.002). Additionally, lower FRα expression was associated with poor overall survival (5-year overall survival: low 13%, intermediate 31%, high 33%; p=0.006). FRα expression (HR=0.61; p=0.03) and Charlson Comorbidity Index (HR=1.16; p=0.01) emerged as independent predictors of survival. The analysis by flow cytometry of 7 PDAC cell lines (AsPC-1, Capan-2, MIA PaCa-2, PANC-1, PDAC2, PDAC3, and PDAC5) demonstrated the highest expression of FRα on the PDAC3 cell line (45%). Therefore, a higher FRα expression is predictive of a favorable prognosis in PDAC and FRα may represent a promising target for novel treatments, including immunotherapy.

A tumor multicomponent targeting chemoimmune drug delivery system for reprograming the tumor microenvironment and personalized cancer therapy

Nanoparticle library engineered with tunable size, shape, and geometry will provide a better idea of targeting multicomponent of tumor microenvironment consisting of epithelial cells, tumor hypoxia, tumor immune cells and angiogenic blood vessels.

Emerging growth factor receptor antagonists for ovarian cancer treatment

INTRODUCTION

Epithelial Ovarian Cancer (EOC) is the most lethal gynecological malignancy. EOC outcomes remain unsatisfactory despite aggressive surgical approach, disease chemo-sensitivity and recent introduction of agents targeting angiogenesis and tumour genome instability. Advances in EOC research have allowed for a tailored treatment approach and accelerated development of novel treatments strategies from bench to bed side, anticipated to improve patient outcomes. Areas covered: Comprehensive review of growth factor receptor antagonists for EOC treatment currently in different stages of development was performed. English peer-reviewed articles and abstracts were searched in MEDLINE, PubMed, Embase and major conferences. We focused on agents that antagonize growth factors promoting sustained proliferative signaling, angiogenesis and evasion of immune destruction blocking the receptor or its stimulating factors. Expert opinion: Receptor signaling has been well characterized for most cancer generating pathways. Growth receptor antagonists are represented by both high receptor affinity monoclonal antibodies as well as tyrosine kinase inhibitors; both are especially effective when a related predictive biomarker of response is identified. Therefore, along with the promising development of novel receptor antagonists or modulators in EOC treatment, targeting essential growth pathways in the tumour and associated microenvironment, is fundamental for biomarker discovery and towards achieving significant improvements in response.

Targeting folate receptor alpha for cancer treatment

Promising targeted treatments and immunotherapy strategies in oncology and advancements in our understanding of molecular pathways that underpin cancer development have reignited interest in the tumor-associated antigen Folate Receptor alpha (FRα). FRα is a glycosylphosphatidylinositol (GPI)-anchored membrane protein. Its overexpression in tumors such as ovarian, breast and lung cancers, low and restricted distribution in normal tissues, alongside emerging insights into tumor-promoting functions and association of expression with patient prognosis, together render FRα an attractive therapeutic target. In this review, we summarize the role of FRα in cancer development, we consider FRα as a potential diagnostic and prognostic tool, and we discuss different targeted treatment approaches with a specific focus on monoclonal antibodies. Renewed attention to FRα may point to novel individualized treatment approaches to improve the clinical management of patient groups that do not adequately benefit from current conventional therapies.

Differential expression of folate receptor 1 in medulloblastoma and the correlation with clinicopathological characters and target therapeutic potential

Medulloblastoma is the most common malignant brain tumor in children. Folate receptor 1 (Folr1) was abundantly expressed in some epithelial malignancies. However the expression profile and the role of clinicopathological significance and therapeutic target potential in medulloblastoma still remain elusive. Currently we detected the expression of Folr1 in medulloblastoma and identified the diagnostic application by evaluating the clinical, pathological and neuroimaging values. Then we developed a target therapeutic compound with Folr1, which exhibited promising efficiency in treatment of medulloblastoma. Folr1 expression was up-regulated in medulloblastoma and positively correlated with percentage of Ki-67 and MMP9 labeling, pathological subtypes, serum Folr1 levels and CSF spreading on MRI. The level of serum Folr1 showed rational sensitivity and specificity in predicting histological subgroups. Strong Folr1 expression was recommended as the independent value regarding the prognosis of patients with medulloblastoma. Folr1 targeted therapy attenuated the tumor growth and metastasis with down-regulation of MMPs proteins and activation of apoptosis. Immunostaining analysis in the xenograft samples showed the decreased Ki-67 and MMP9 index providing the strong evidences that Folr1 targeted application can suppress the proliferation and invasion. Our findings uncovered in Folr1 a predictive candidate and therapeutic target for medulloblastoma.

Folic acid-functionalized graphene quantum dots with tunable fluorescence emission for cancer cell imaging and optical detection of Hg2+

Functional groups may alter the optical and electrical characteristics of graphene quantum dots and lead to unusual properties and related applications.

Multimodal molecular 3D imaging for the tumoral volumetric distribution assessment of folate-based biosensors

The aim of this study was to characterize the in vivo volumetric distribution of three folate-based biosensors by different imaging modalities (X-ray, fluorescence, Cerenkov luminescence, and radioisotopic imaging) through the development of a tridimensional image reconstruction algorithm. The preclinical and multimodal Xtreme imaging system, with a Multimodal Animal Rotation System (MARS), was used to acquire bidimensional images, which were processed to obtain the tridimensional reconstruction. Images of mice at different times (biosensor distribution) were simultaneously obtained from the four imaging modalities. The filtered back projection and inverse Radon transformation were used as main image-processing techniques. The algorithm developed in Matlab was able to calculate the volumetric profiles of ^99mTc-Folate-Bombesin (radioisotopic image), ¹⁷⁷Lu-Folate-Bombesin (Cerenkov image), and FolateRSense™ 680 (fluorescence image) in tumors and kidneys of mice, and no significant differences were detected in the volumetric quantifications among measurement techniques. The imaging tridimensional reconstruction algorithm can be easily extrapolated to different 2D acquisition-type images. This characteristic flexibility of the algorithm developed in this study is a remarkable advantage in comparison to similar reconstruction methods.

Leukemia-specific delivery of mutant NOTCH1 targeted therapy

NOTCH1 is an attractive cancer target, particularly in T cell acute lymphoblastic leukemia (T-ALL), with activating mutations in this gene identified in more than 50% of cases. In this study, Roti et al. describe the synthesis, characterization, and validation of JQ-FT, a first-in-class NOTCH1 inhibitor that has dual selectivity for leukemia over normal cells and NOTCH1 mutants over wild-type receptors.

On-target drug delivery remains a challenge in cancer precision medicine; it is difficult to deliver a targeted therapy to cancer cells without incurring toxicity to normal tissues. The SERCA (sarco-endoplasmic reticulum Ca²⁺ ATPase) inhibitor thapsigargin inhibits mutant NOTCH1 receptors compared with wild type in T cell acute lymphoblastic leukemia (T-ALL), but its administration is predicted to be toxic in humans. Leveraging the addiction of ALL to folic acid, we conjugated folate to an alcohol derivative of thapsigargin via a cleavable ester linkage. JQ-FT is recognized by folate receptors on the plasma membrane and delivered into leukemia cells as a potent antileukemic agent. In mechanistic and translational models of T-ALL, we demonstrate NOTCH1 inhibition in vitro and in vivo. These proof-of-concept studies support the further optimization of this first-in-class NOTCH1 inhibitor with dual selectivity: leukemia over normal cells and NOTCH1 mutants over wild-type receptors. Furthermore, tumor-specific disruption of Notch signaling may overcome legitimate concerns associated with the tumor suppressor function of nontargeted Notch pathway inhibitors.

Expression and characterization of the zebrafish orthologue of the human FOLR1 gene during embryogenesis

It has been well established that many types of rapidly dividing normal and diseased cells require an increased amount of folate for DNA replication and repair as well as cellular metabolism. Thus one of folate's cognate receptors, Folate Receptor 1 (FOLR1) is usually up-regulated in rapidly dividing cells, including many types of cancerous tumors. Because zebrafish have become a model organism for understanding conserved vertebrate cellular pathways and human disease, there has been an increased need to identify and elucidate orthologous zebrafish genes that are central to known human maladies. The cells of all early animal embryos go through a phase of rapid division (cleavage) where particular cell cycle checkpoints are skipped until a specification event occurs directing these embryonic stem cells to their fated germ layer cell type. Interestingly, this rapid cell division that ignores cell cycle checkpoints is also observed in many cancers. Developing blastula and tumor cells both require folr1 expression to obtain folate. In this report we have identified the expression pattern of the zebrafish gene zgc:165502, located on chromosome 15. Using computational and comparative methods and molecular biology techniques such as reverse transcription polymerase chain reaction (RT-PCR) and whole mount in situ hybridization (WISH) during embryogenesis, we demonstrate that zgc:165502 is the zebrafish orthologue of the human FOLR1 gene. Understanding when and where FOLR1 orthologues are expressed in different biomedical model organisms such as the zebrafish will help researchers design better experiments to study the endogenous FOLR1 activity.

Cellular uptake of nanoparticles: journey inside the cell

Nanoscale materials are increasingly found in consumer goods, electronics, and pharmaceuticals. While these particles interact with the body in myriad ways, their beneficial and/or deleterious effects ultimately arise from interactions at the cellular and subcellular level. Nanoparticles (NPs) can modulate cell fate, induce or prevent mutations, initiate cell-cell communication, and modulate cell structure in a manner dictated largely by phenomena at the nano-bio interface. Recent advances in chemical synthesis have yielded new nanoscale materials with precisely defined biochemical features, and emerging analytical techniques have shed light on nuanced and context-dependent nano-bio interactions within cells. In this review, we provide an objective and comprehensive account of our current understanding of the cellular uptake of NPs and the underlying parameters controlling the nano-cellular interactions, along with the available analytical techniques to follow and track these processes.

Potent Therapeutic Activity Against Peritoneal Dissemination and Malignant Ascites by the Novel Anti-Folate Receptor Alpha Antibody KHK2805

Many ovarian cancer patients often show peritoneal metastasis with malignant ascites. However, unmet medical needs remain regarding controlling these symptoms after tumors become resistant to chemotherapies. We developed KHK2805, a novel anti-folate receptor α (FOLR1) humanized antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). The primary aim of the present study was to evaluate whether the anti-tumor activity of KHK2805 was sufficient for therapeutic application against peritoneal dissemination and malignant ascites of platinum-resistant ovarian cancer in preclinical models. Here, both the ADCC and CDC of KHK2805 were evaluated in ovarian cancer cell lines and patient-derived samples. The anti-tumor activity of KHK2805 was evaluated in a SCID mouse model of platinum-resistant peritoneal dissemination. As results, KHK2805 showed specific binding to FOLR1 with high affinity at a novel epitope. KHK2805 exerted potent ADCC and CDC against ovarian cancer cell lines. Furthermore, primary platinum-resistant malignant ascites cells were susceptible to autologous ADCC with KHK2805. Patient-derived sera and malignant ascites induced CDC of KHK2805. KHK2805 significantly reduced the total tumor burden and amount of ascites in SCID mice with peritoneal dissemination and significantly prolonged their survival. In addition, the parental rat antibody strongly stained serous and clear cell-type ovarian tumors by immunohistochemistry. Overall, KHK2805 showed cytotoxicity against both ovarian cancer cell lines and patient-derived cells. These translational study findings suggest that KHK2805 may be promising as a novel therapeutic agent for platinum-resistant ovarian cancer with peritoneal dissemination and malignant ascites.

Folic acid conjugated polymeric micelles loaded with a curcumin difluorinated analog for targeting cervical and ovarian cancers

The current study utilizes folic acid conjugated poly(styrene-co-maleic anhydride) block copolymer (FA-SMA) to enhance the solubility of a hydrophobic but very potent synthetic curcumin-difluorinated (CDF) analog and its targeted delivery to folate receptor-alpha overexpressing cancers. The nanomicelles showed high aqueous solubility. Importantly, the encapsulation of CDF in nanomicelles resulted in high photo-stability of the otherwise photo-labile drug. When the nanomicelles were tested in folate-receptor overexpressing ovarian and cervical cancer cells they exhibited high anticancer activity causing significant cell population to undergo apoptosis due to upregulation of tumor suppressor phosphatase and tensin homolog (PTEN) and inhibition of nuclear factor kappa-B (NFκB), which further confirmed the targeting ability and anticancer potentials of folate-targeted formulations.

Ovarian cancer: Novel molecular aspects for clinical assessment

Ovarian cancer is a very heterogeneous tumor which has been traditionally characterized according to the different histological subtypes and differentiation degree. In recent years, innovative molecular screening biotechnologies have allowed to identify further subtypes of this cancer based on gene expression profiles, mutational features, and epigenetic factors. These novel classification systems emphasizing the molecular signatures within the broad spectrum of ovarian cancer have not only allowed a more precise prognostic prediction, but also proper therapeutic strategies for specific subgroups of patients. The bulk of available scientific data and the high refinement of molecular classifications of ovarian cancers can today address the research towards innovative drugs with the adoption of targeted therapies tailored for single molecular profiles leading to a better prediction of therapeutic response. Here, we summarize the current state of knowledge on the molecular bases of ovarian cancer, from the description of its molecular subtypes derived from wide high-throughput analyses to the latest discoveries of the ovarian cancer stem cells. The latest personalized treatment options are also presented with recent advances in using PARP inhibitors, anti-angiogenic, anti-folate receptor and anti-cancer stem cells treatment approaches.

Bacterial Folates Provide an Exogenous Signal for C. elegans Germline Stem Cell Proliferation

Here we describe an in vitro primary culture system for Caenorhabditis elegans germline stem cells. This culture system was used to identify a bacterial folate as a positive regulator of germ cell proliferation. Folates are a family of B-complex vitamins that function in one-carbon metabolism to allow the de novo synthesis of amino acids and nucleosides. We show that germ cell proliferation is stimulated by the folate 10-formyl-tetrahydrofolate-Glun both in vitro and in animals. Other folates that can act as vitamins to rescue folate deficiency lack this germ cell stimulatory activity. The bacterial folate precursor dihydropteroate also promotes germ cell proliferation in vitro and in vivo, despite its inability to promote one-carbon metabolism. The folate receptor homolog FOLR-1 is required for the stimulation of germ cells by 10-formyl-tetrahydrofolate-Glun and dihydropteroate. This work defines a folate and folate-related compound as exogenous signals to modulate germ cell proliferation.

Rapid and Selective Determination of Folate Receptor α with Sensitive Resonance Rayleigh Scattering Signal

A rapid, simple, and novel method for folate receptor α (FRα) determination is reported here. A probe of gold nanoparticles (Au NPs) modified with anti-FRα antibody was synthesized under the optimized conditions first. The antibody-modified Au NPs would aggregate when FRα was added to the probe for the specific interaction between antibody and antigen, resulting in the enhancement of resonance Rayleigh scattering (RRS) intensity. There is a linear relationship between the change of RRS intensity (ΔI_RRS) and the concentration of FRα, with the detecting range of 0.50–37.50 ng·mL⁻¹ and the limit of determination of 0.05 ng·mL⁻¹. The determination of FRα in serum samples was realized with the advantages of high selectivity, high sensitivity, and easy operation.

Folic Acid-Targeted Etoposide Cubosomes for Theranostic Application of Cancer Cell Imaging and Therapy

Background

The aim of this study was to develop a novel Poloxamer-based drug delivery system featuring a tumor-targeting folate moiety, which was expected to provide better targeting properties and therapeutic effects compared with the traditional cubosomes (Cubs).

Material/Methods

Both folate-modified Cubs containing etoposide (ETP-Cubs-FA) and normal cubic nanoparticles loaded with etoposide (ETP-Cubs) were prepared through the fragmentation of bulk gels under the homogenization condition of 1500 bar, and a mean particle size of around 180 nm was obtained with a narrow size distribution. The cubosomes were further characterized by differential scanning calorimetry (DSC) and Polarized light microscopy (PLM). The release of ETP in vitro from these nanoparticles was found to be 82.5% at 36 h, showing a sustained release property compared with the free drug administration.

Results

Folate-modified cubosomes exhibited best anti-proliferative activity followed by normal cubosomes and the free drug. A further cell uptake study of Rhodamine B-loaded Cubs-FA (Rh-B-Cubs-FA) showed a marked increase of cellular accumulation compared with free Rh-B and Rh-B-loaded Cubs (Rh-B-Cubs). In vivo Rh-B-based tumor imaging demonstrated that Cubs-FA specifically targeted the tumor tissue.

Conclusions

The folate-modified cubosomes containing ETP may be a promising drug candidate for antitumor treatment.

Folic Acid Modulates DMBA/TPA-Induced Changes in Skin of Mice: A Study Relevant to Carcinogenesis

The present study was aimed at investigating the modulatory effects of folic acid (FA) on early stages of chemically induced skin cancer. For this, a two-stage model of skin tumorigenesis was employed. 7,12-Dimethylbenz(a)anthracene (DMBA, 500 nmol/100 ul of acetone) was applied topically for two weeks (twice weekly), followed by phorbol-12-myristate-13-acetate (TPA, 1.7 nmol/100 ul) twice weekly for six weeks on the depilated skin of mice, and FA was administered orally at a dose of 40 microgram/animal for 10 weeks daily. Balb/c mice were divided into four groups depending upon the treatment they received (control, DMBA/TPA, FA, and FA+DMBA/TPA). DMBA/TPA treatment led to the formation of papillomas in DMBA/TPA and FA+DMBA/TPA groups. Ornithine decarboxylase (ODC), proliferating cell nuclear antigen (PCNA), epidermal thickness, and cell count were evaluated to assess the beneficial effects in the early stages. FA exhibited its ameliorative potential as indicated by decreased epidermal thickness and cell count in FA+DMBA/TPA group when compared to DMBA/TPA group. Concomitantly, FA decreased the expression of ODC and PCNA in skin and activity of serum lactate dehydrogenase, suggesting inhibitory effects on cell proliferation and cell damage. Differential modulation in lipid peroxidation and reduced glutathione was observed in response to DMBA/TPA treatment and its intervention with FA. Although these findings suggest the inhibitory potential of FA during initial stages of murine skin cancer, detailed studies are warranted considering the ambiguous reports available in literature regarding the association of FA and cancer.

Folate/N-acetyl glucosamine conjugated mesoporous silica nanoparticles for targeting breast cancer cells: A comparative study

Folate receptors (FR) have been well recognized as a marker to target nano-sized carriers for cancer diagnosis and therapy. In contrast, influx transport systems (e.g. GLUT transporters) that transport essential amino acids and nutrients to cancer cells have not been exploited much for targeted delivery. In this study, folic acid- or n-acetyl glucosamine- functionalized mesoporous silica nanoparticles loaded with doxorubicin (DOX-FA-MSNPs or DOX-NAG-MSNPs) were prepared, characterized and compared for targeting along with cytotoxicity towards MCF-7 and MDA-MB-231 human breast cancer cells. Cellular uptake of FITC tagged FA-MSNPs and NAG-MSNPs were evaluated by confocal microscopy and flow cytometry in above-mentioned cancer cell lines. The result suggested higher cellular uptake of NAG-MSNPs than FA-MSNPs for both the cell lines. Cytotoxicity of free DOX, DOX-MSNPs, DOX-FA-MSNPs and DOX-NAG-MSNPs were evaluated on both the breast cancer cell lines. Cytotoxicity results showed that DOX-loaded NAG-MSNPs exerted significant higher cytotoxicity effect on both the cell lines than DOX-FA-MSNPs. Moreover, both the targeted formulations were more effective than free DOX. Our results suggested that GLUT transporters can be effectively utilized for nanoparticles internalization in breast cancer cells.

pH-sensitive Au-BSA-DOX-FA nanocomposites for combined CT imaging and targeted drug delivery

Albumin-based nanoparticles (NPs) as a drug delivery system have attracted much attention owing to their nontoxicity, non-immunogenicity, great stability and ability to bind to many therapeutic drugs. Herein, bovine serum albumin (BSA) was utilized as a template to prepare Au–BSA core/shell NPs. The outer layer BSA was subsequently conjugated with cis-aconityl doxorubicin (DOX) and folic acid (FA) to create Au–BSA–DOX–FA nanocomposites. A list of characterizations was undertaken to identify the successful conjugation of drug molecules and targeted agents. In vitro cytotoxicity using a cell counting kit-8 (CCK-8) assay indicated that Au–BSA NPs did not display obvious cytotoxicity to MGC-803 and GES-1 cells in the concentration range of 0–100 μg/mL, which can therefore be used as a safe drug delivery carrier. Furthermore, compared with free DOX, Au–BSA–DOX–FA nanocomposites exhibited a pH-sensitive drug release ability and superior antitumor activity in a drug concentration-dependent manner. In vivo computed tomography (CT) imaging experiments showed that Au–BSA–DOX–FA nanocomposites could be used as an efficient and durable CT contrast agent for targeted CT imaging of the folate receptor (FR) overexpressed in cancer tissues. In vivo antitumor experiments demonstrated that Au–BSA–DOX–FA nanocomposites have selective antitumor activity effects on FR-overexpressing tumors and no adverse effects on normal tissues and organs. In conclusion, the Au–BSA–DOX–FA nanocomposite exhibits selective targeting activity, X-ray attenuation activity and pH-sensitive drug release activity. Therefore, it can enhance CT imaging and improve the targeting therapeutic efficacy of FR-overexpressing gastric cancers. Our findings suggest that Au–BSA–DOX–FA nanocomposite is a novel drug delivery carrier and a promising candidate for cancer theranostic applications.

Polymeric Nanoparticle-Mediated Gene Delivery for Lung Cancer Treatment

In recent years, researchers have focused on targeted gene therapy for lung cancer, using nanoparticle carriers to overcome the limitations of conventional treatment methods. The main goal of targeted gene therapy is to develop more efficient therapeutic strategies by improving the bioavailability, stability, and target specificity of gene therapeutics and to reduce off-target effects. Polymer-based nanoparticles, an alternative to lipid and inorganic nanoparticles, efficiently carry nucleic acid therapeutics and are stable in vivo. Receptor-targeted delivery is a promising approach that can limit non-specific gene delivery and can be achieved by modifying the polymer nanoparticle surface with specific receptor ligands or antibodies. This review highlights the recent developments in gene delivery using synthetic and natural polymer-based nucleic acid carriers for lung cancer treatment. Various nanoparticle systems based on polymers and polymer combinations are discussed. Further, examples of targeting ligands or moieties used in targeted, polymer-based gene delivery to lung cancer are reviewed.

Modification of cytokine-induced killer cells with folate receptor alpha (FRα)-specific chimeric antigen receptors enhances their antitumor immunity toward FRα-positive ovarian cancers

Folate receptor alpha (FRα) is aberrantly expressed in ovarian cancers but largely absent in normal tissues, and therefore represents an attractive target for immunotherapy. In recent years, modification of T cells with chimeric antigen receptor (CAR) targeting FRα has been reported to improve antitumor immunity of T cells. However, there are limited data regarding CAR-modified cytokine-induced killer (CAR-CIK) cells. In the present study, we modified CIK cells with FRα-specific CARs and investigated their antitumor immunity against ovarian cancers. We found that both non-transduced and mock CAR-transduced CIK cells showed only low antitumor activity against either FRα-positive (FRα⁺) or FRα-negative (FRα^-) targets. However, all three generations of CAR-modified CIK cells showed enhanced antitumor activity against FRα⁺ targets, but not FRα^- targets. First-generation ζ-CAR-CIK cells increased production of IFN-γ, enhanced short-term cytotoxicity against FRα⁺ ovarian cancer cells, and showed modest and short-term suppression of established tumors; while second-generation 28ζ- and third-generation 28BBζ-CAR-CIK cells showed significant proliferation, enhanced secretion of IL-2, eliminated the FRα⁺ ovarian cancer cells in long-term co-culture, and showed dramatic and long-term inhibition of tumor growth and prolonged survival of xenograft-bearing mice. It is noteworthy that the 28BBζ-CAR was more potent in the modification of CIK cells than 28ζ-CAR both in vitro and in vivo. Moreover, CAR-CIK cells showed more efficient anticancer activity compared with CAR-T cells in vitro, but less efficient than CAR-T cells in vivo. According to these results, we conclude that modification of CIK cells with FRα-specific CARs enhances their antitumor immunity to FRα⁺ ovarian cancers. The third-generation 28BB-ζ CAR containing 4-1BB co-stimulation was more efficient in modification of CIK cells than either first-generation ζ-CAR or second-generation CD28-ζ-CAR.

The role of urinary pteridines as disease biomarkers

Pteridines and their derivatives function as intermediates in the metabolism of several vitamins and cofactors, and their relevance to disease has inspired new efforts to study their roles as disease biomarkers. Recent analytical advances, such as the emergence of sensitive mass spectrometry techniques, new workflows for measuring pteridine derivatives in their native oxidation states and increased multiplexing capacities for the simultaneous determination of many pteridine derivatives, have enabled researchers to explore the roles of urinary pteridines as disease biomarkers at much lower levels with greater accuracy than with previous technologies or methods. As a result, urinary pteridines are being increasingly studied as putative cancer biomarkers with promising results being reported from exploratory studies. In addition, the role of urinary neopterin as a universal biomarker for immune system activation is being investigated in new diseases where it is anticipated to become a useful supplementary marker in clinical diagnostic settings. In summary, this review provides an overview of recent developments in the clinical study of urinary pteridines as disease biomarkers, covers the most promising aspects of advanced analytical techniques being developed for the determination of urinary pteridines and discusses the major challenges associated with implementing pteridine biomarkers in clinical laboratory settings.

Folate-mediated chemotherapy and diagnostics: An updated review and outlook

Folate receptor (FR) is highly expressed in many types of human cancers, and it has been actively studied for developing targeted chemotherapy and diagnostic agents. Tremendous efforts have been made in developing FR-targeted nanomedicines and nanoprobes and translating them into clinical applications. This article provides a concise review on the latest development of folate-mediated nanomedicines and nanoprobes for chemotherapy and diagnostics with an emphasis on in vivo applications. The cellular uptake mechanisms, pharmacokinetics (PK), administration routes and major challenges in FR-targeted nanoparticles are discussed.

High folic acid diet enhances tumour growth in PyMT-induced breast cancer

Background:

The B-vitamin folate is among the most studied bioactive food compound, and a dietary intake meeting the daily requirements has been found to reduce the risk of cancer and cardiovascular diseases as well as preventing neural tube defects during fetal development. Several countries have therefore introduced dietary fortification with folic acid. However, clinical and animal studies suggest that folic acid has a dual role in cancer development.

Methods:

During the period of initial tumour progression, MMTV-PyMT (MMTV-polyoma virus middle T) transgenic mice were fed with normal diet and high folic acid diet.

Results:

We found that PyMT-induced breast tumours highly express the cancer-specific folate receptor (FR), a feature they share with several human epithelial cancers in which expression of FRα correlates with tumour grade. Mice receiving a high folic acid diet displayed a significantly increased tumour volume compared with mice receiving normal diet. In the largest tumours, only found in mice on high folic acid diet, STAT3 was activated. In primary cells from PyMT tumours, STAT3 was activated upon treatment with folic acid in culture.

Conclusions:

Our results offer a novel molecular explanation for folic acid-induced growth of existing tumours.

Folate receptor alpha is more than just a folate transporter

Until recently folate receptor alpha (FRα) has only been considered as a folate transporter. However, a novel role of FRα as a transcription factor was reported by our lab. More recently our lab showed a novel pleiotropic role of FRα: (a) direct transcriptional activation of Oct4, Sox2, and Klf4 genes; and (b) repression of biogenesis of miRNAs that target these genes or their effector molecules. These observations beg a question: "Can a simple molecule such as folate be used to manipulate the production and/or differentiation of endogenous neural stem cells (NSCs), which may hold promise for future therapies?" Conditions such as spinal cord injury, motor neuron diseases, Alzheimer's disease and multiple sclerosis may benefit from increasing stem cell pool and promoting specific pathways of differentiation. On the flip-side, these NSCs may also contribute to some CNS tumors therefore promoting differentiation could prove more beneficial. FRα may hold promises for both since it has the potential to remodel chromatin in a context dependent manner. In this commentary we discuss our previous data and new questions arising in the context of the new role for FRα.

Structural analysis of binding functionality of folic acid-PEG dendrimers against folate receptor

Dendrimers functionalized with folic acid (FA) are drug delivery systems that can selectively target cancer cells with folate receptors (FR-α) overexpression. Incorporation of polyethylene glycol (PEG) can enhance dendrimers solubility and pharmacokinetics, but ligand-receptor binding must not be affected. In this work we characterized, at atomic level, the binding functionality of conventional site-specific dendrimers conjugated with FA with PEG 750 or PEG 3350 as a linker. After Molecular Dynamics simulation, we observed that both PEG's did not interfere over ligand-receptor binding functionality. Although binding kinetics could be notably affected, the folate fragment from both dendrimers remained exposed to the solvent before approaching selectively to FR-α. PEG 3350 provided better solubility and protection from enzymatic degradation to the dendrimer than PEG 750. Also, FA-PEG3350 dendrimer showed a slightly better interaction with FR-α than FA-PEG750 dendrimer. Therefore, theoretical evidence supports that both dendrimers are suitable as drug delivery systems for cancer therapies.

Folic acid-conjugated carbon dots as green fluorescent probes based on cellular targeting imaging for recognizing cancer cells

Green fluorescent CDs using the natural product dandelion as a carbon source were covalently conjugated with folate to differentiate cancer cells from normal cells.

Folic acid on iron oxide nanoparticles: platform with high potential for simultaneous targeting, MRI detection and hyperthermia treatment of lymph node metastases of prostate cancer

Folic acid directly bound to the surface of iron oxide nanoparticles with simultaneously high targeting, MRI relaxivity and heating efficacy.