Evaluation of folate receptor 1 (FOLR1) mRNA expression, its specific promoter methylation and global DNA hypomethylation in type I and type II ovarian cancers

Folate Receptor Alpha-A Novel Approach to Cancer Therapy

Folate receptor α (FR) was discovered many decades ago, along with drugs that target intracellular folate metabolism, such as pemetrexed and methotrexate. Folate is taken up by the cell via this receptor, which also targeted by many cancer agents due to the over-expression of the receptor by cancer cells. FR is a membrane-bound glycosyl-phosphatidylinositol (GPI) anchor glycoprotein encoded by the folate receptor 1 (FOLR1) gene. FR plays a significant role in DNA synthesis, cell proliferation, DNA repair, and intracellular signaling, all of which are essential for tumorigenesis. FR is more prevalent in cancer cells compared to normal tissues, which makes it an excellent target for oncologic therapeutics. FRα is found in many cancer types, including ovarian cancer, non-small-cell lung cancer (NSCLC), and colon cancer. FR is widely used in antibody drug conjugates, small-molecule-drug conjugates, and chimeric antigen-receptor T cells. Current oncolytic therapeutics include mirvetuximab soravtansine, and ongoing clinical trials are underway to investigate chimeric antigen receptor T cells (CAR-T cells) and vaccines. Additionally, FRα has been used in a myriad of other applications, including as a tool in the identification of tumor types, and as a prognostic marker, as a surrogate of chemotherapy resistance. As such, FRα identification has become an essential part of precision medicine.

FOLR1-stabilized β-catenin promotes laryngeal carcinoma progression through EGFR/AKT/GSK-3β pathway

Folate receptor 1 (FOLR1) is overexpressed in numerous epithelial malignancies; however, its role in laryngeal squamous cell carcinoma (LSCC) remains unclear. In the present study, we demonstrated that FOLR1 messenger RNA and protein expression levels were higher in LSCC tissues than in the adjacent normal tissues. Additionally, FOLR1 promoted the proliferation and migration of LSCC cells, whereas small interfering RNA-mediated knockdown of β-catenin abolished these effects. Moreover, FOLR1 stabilizes β-catenin by inhibiting its ubiquitination and degradation. Furthermore, blocking the interaction between epidermal growth factor receptor (EGFR) and the EGFR/AKT/glycogen synthase (GSK)3β signaling axis both abolished FOLR1's effects on the expression and nuclear aggregation of β-catenin. In summary, our work reveals a novel mode in which FOLR1 promotes the proliferation and migration of LSCC by enhancing the stability and nuclear translocation of β-catenin through the EGFR/AKT/GSK3β axis.

Signaling via a CD28/CD40 chimeric costimulatory antigen receptor (CoStAR™), targeting folate receptor alpha, enhances T cell activity and augments tumor reactivity of tumor infiltrating lymphocytes

Transfer of autologous tumor infiltrating lymphocytes (TIL) to patients with refractory melanoma has shown clinical efficacy in a number of trials. However, extending the clinical benefit to patients with other cancers poses a challenge. Inefficient costimulation in the tumor microenvironment can lead to T cell anergy and exhaustion resulting in poor anti-tumor activity. Here, we describe a chimeric costimulatory antigen receptor (CoStAR) comprised of FRα-specific scFv linked to CD28 and CD40 intracellular signaling domains. CoStAR signaling alone does not activate T cells, while the combination of TCR and CoStAR signaling enhances T cell activity resulting in less differentiated T cells, and augmentation of T cell effector functions, including cytokine secretion and cytotoxicity. CoStAR activity resulted in superior T cell proliferation, even in the absence of exogenous IL-2. Using an in vivo transplantable tumor model, CoStAR was shown to improve T cell survival after transfer, enhanced control of tumor growth, and improved host survival. CoStAR could be reliably engineered into TIL from multiple tumor indications and augmented TIL activity against autologous tumor targets both in vitro and in vivo. CoStAR thus represents a general approach to improving TIL therapy with synthetic costimulation.

Therapeutic strategies targeting folate receptor α for ovarian cancer

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and presents a major clinical challenge due to limited treatment options. Folate receptor alpha (FRα), encoded by the FOLR1 gene, is an attractive therapeutically target due to its prevalent and high expression in EOC cells. Recent basic and translational studies have explored several modalities, such as antibody-drug conjugate (ADC), monoclonal antibodies, small molecules, and folate-drug conjugate, to exploit FRα for EOC treatment. In this review, we summarize the function of FRα, and clinical efficacies of various FRα-based therapeutics. We highlight mirvetuximab soravtansine (MIRV), or Elahere (ImmunoGen), the first FRα-targeting ADC approved by the FDA to treat platinum-resistant ovarian cancer. We discuss potential mechanisms and management of ocular adverse events associated with MIRV administration.

Recent Progress in Second Near-Infrared (NIR-II) Fluorescence Imaging in Cancer

Cancer continues to be one of the leading causes of death worldwide, and its incidence is on the rise. Although cancer diagnosis and therapy have advanced significantly in recent decades, it is still a challenge to achieve the accurate identification and localization of cancer and to complete tumor elimination with a maximum preservation of normal tissue. Recently, second near-infrared region (NIR-II, 1000-1700 nm) fluorescence has shown great application potential in cancer theranostics due to its inherent advantages, such as great penetration capacity, minimal tissue absorption and scattering, and low autofluorescence. With the development of fluorescence imaging systems and fluorescent probes, tumor detection, margin definition, and individualized therapy can be achieved quickly, enabling an increasingly accurate diagnosis and treatment of cancer. Herein, this review introduces the role of NIR-II fluorescence imaging in cancer diagnosis and summarizes the representative applications of NIR-II image-guided treatment in cancer therapy. Ultimately, we discuss the present challenges and future perspectives on fluorescence imaging in the field of cancer theranostics and put forward our opinions on how to improve the accuracy and efficiency of cancer diagnosis and therapeutics.

Modulation of DNA/RNA Methylation Signaling Mediating Metabolic Homeostasis in Cancer

Nucleic acid methylation is a fundamental epigenetic mechanism that impinges upon several cellular attributes, including metabolism and energy production. The dysregulation of deoxyribonucleic acid (DNA)/ribonucleic acid (RNA) methylation can lead to metabolic rewiring in the cell, which in turn facilitates tumor development. Here, we review the current knowledge on the interplay between DNA/RNA methylation and metabolic programs in cancer cells. We also discuss the mechanistic role of these pathways in tumor development and progression.

Losing DNA methylation at repetitive elements and breaking bad

Background

DNA methylation is an epigenetic chromatin mark that allows heterochromatin formation and gene silencing. It has a fundamental role in preserving genome stability (including chromosome stability) by controlling both gene expression and chromatin structure. Therefore, the onset of an incorrect pattern of DNA methylation is potentially dangerous for the cells. This is particularly important with respect to repetitive elements, which constitute the third of the human genome.

Main body

Repetitive sequences are involved in several cell processes, however, due to their intrinsic nature, they can be a source of genome instability. Thus, most repetitive elements are usually methylated to maintain a heterochromatic, repressed state. Notably, there is increasing evidence showing that repetitive elements (satellites, long interspersed nuclear elements (LINEs), Alus) are frequently hypomethylated in various of human pathologies, from cancer to psychiatric disorders. Repetitive sequences’ hypomethylation correlates with chromatin relaxation and unscheduled transcription. If these alterations are directly involved in human diseases aetiology and how, is still under investigation.

Conclusions

Hypomethylation of different families of repetitive sequences is recurrent in many different human diseases, suggesting that the methylation status of these elements can be involved in preservation of human health. This provides a promising point of view towards the research of therapeutic strategies focused on specifically tuning DNA methylation of DNA repeats.

Decitabine Sensitizes the Radioresistant Lung Adenocarcinoma to Pemetrexed Through Upregulation of Folate Receptor Alpha

Chemotherapy is the backbone of subsequent treatment for patients with lung adenocarcinoma (LUAD) exhibiting radiation resistance, and pemetrexed plays a critical role in this chemotherapy. However, few studies have assessed changes in the sensitivity of LUAD cells to pemetrexed under radioresistant circumstances. Therefore, the objectives of this study were to delineate changes in the sensitivity of radioresistant LUAD cells to pemetrexed and to elucidate the related mechanisms and then develop an optimal strategy to improve the cytotoxicity of pemetrexed in radioresistant LUAD cells. Our study showed a much lower efficacy of pemetrexed in radioresistant cells than in parental cells, and the mechanism of action was the significant downregulation of folate receptor alpha (FRα) by long-term fractionated radiotherapy, which resulted in less cellular pemetrexed accumulation. Interestingly, decitabine effectively reversed the decrease in FRα expression in radioresistant cells through an indirect regulatory approach. Thereafter, we designed a combination therapy of pemetrexed and decitabine and showed that the activation of FRα by decitabine sensitizes radioresistant LUAD cells to pemetrexed both in vitro and in xenografts. Our findings raised a question regarding the administration of pemetrexed to patients with LUAD exhibiting acquired radioresistance and accordingly suggested that a combination of pemetrexed and decitabine would be a promising treatment strategy.

Atypical teratoid/rhabdoid tumors (ATRTs) with SMARCA4 mutation are molecularly distinct from SMARCB1-deficient cases

Atypical teratoid/rhabdoid tumors (ATRTs) are very aggressive childhood malignancies of the central nervous system. The underlying genetic cause are inactivating bi-allelic mutations in SMARCB1 or (rarely) in SMARCA4. ATRT-SMARCA4 have been associated with a higher frequency of germline mutations, younger age, and an inferior prognosis in comparison to SMARCB1 mutated cases. Based on their DNA methylation profiles and transcriptomics, SMARCB1 mutated ATRTs have been divided into three distinct molecular subgroups: ATRT-TYR, ATRT-SHH, and ATRT-MYC. These subgroups differ in terms of age at diagnosis, tumor location, type of SMARCB1 alterations, and overall survival. ATRT-SMARCA4 are, however, less well understood, and it remains unknown, whether they belong to one of the described ATRT subgroups. Here, we examined 14 ATRT-SMARCA4 by global DNA methylation analyses. We show that they form a separate group segregating from SMARCB1 mutated ATRTs and from other SMARCA4-deficient tumors like small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) or SMARCA4 mutated extra-cranial malignant rhabdoid tumors. In contrast, medulloblastoma (MB) samples with heterozygous SMARCA4 mutations do not group separately, but with established MB subgroups. RNA sequencing of ATRT-SMARCA4 confirmed the clustering results based on DNA methylation profiling and displayed an absence of typical signature genes upregulated in SMARCB1 deleted ATRT. In summary, our results suggest that, in line with previous clinical observations, ATRT-SMARCA4 should be regarded as a distinct molecular subgroup.

Detection of membrane receptors on per tumor cell by nonimmobilized cell capillary electrophoresis and a mathematic model

Folate receptors (FRs) are a class of valuable therapeutic target which is highly expressed on a variety of cancers. The accurate detection of the expression of FRs in different cells is conducive to improve the accuracy of FR targeted tumor therapy. Herein, a method based on nonimmobilized cell capillary electrophoresis (NICCE) combined with a mathematic model to quantify FRs on each single tumor cell was developed. At first, we studied the interactions between FA and A549, HT-29, HepG2, and U87MG cells by NICCE respectively, and calculated the kinetic parameters (Ka, k', ka, and kd). Next, we established a mathematic model to accurately determine the number of moles of FRs on per A549, HT-29, HepG2, and U87MG cell for the first time, that were (10.44 ± 0.53) × 10-19 mol, (34.32 ± 1.33) × 10-19 mol, (337.14 ± 10.11) × 10-19 mol, and (37.31 ± 2.13) × 10-19 mol. Then, these re-sults were proved to be consistent with the results of enzyme-linked immunosorbent assay (ELISA). Therefore, this method is simple, rapid, sensitive, and without protein separation or purification, which is expected to achieve clinical detection of cell membrane receptor expression level of cell membrane receptors on a single cell, which may be greatly beneficial to further clinical diagnosis and therapy.

Driving Immune Responses in the Ovarian Tumor Microenvironment

Ovarian cancer is the leading cause of death among gynecological neoplasms, with an estimated 14,000 deaths in 2019. First-line treatment options center around a taxane and platinum-based chemotherapy regimen. However, many patients often have recurrence due to late stage diagnoses and acquired chemo-resistance. Recent approvals for bevacizumab and poly (ADP-ribose) polymerase inhibitors have improved treatment options but effective treatments are still limited in the recurrent setting. Immunotherapy has seen significant success in hematological and solid malignancies. However, effectiveness has been limited in ovarian cancer. This may be due to a highly immunosuppressive tumor microenvironment and a lack of tumor-specific antigens. Certain immune cell subsets, such as regulatory T cells and tumor-associated macrophages, have been implicated in ovarian cancer. Consequently, therapies augmenting the immune response, such as immune checkpoint inhibitors and dendritic cell vaccines, may be unable to properly enact their effector functions. A better understanding of the various interactions among immune cell subsets in the peritoneal microenvironment is necessary to develop efficacious therapies. This review will discuss various cell subsets in the ovarian tumor microenvironment, current immunotherapy modalities to target or augment these immune subsets, and treatment challenges.

A systematic review and meta-analysis of higher expression of folate receptor alpha (FOLR1) predicts poor cancer prognosis

Folate receptor alpha (FOLR1), a glycosylphosphatidylinositol-linked protein, is a well characterized folate transporter. However, the prognostic power of FOLR1 in cancer remains controversial. We conducted a meta-analysis to assess the prognostic roles of FOLR1 on different cancers. Twelve studies involving 4471 patients were included in this meta-analysis. The pooled analysis indicated that high FOLR1 significantly predicted poor overall survival (OS) (pooled hazard ratio (HR) = 0.78, 95% confidence interval (CI) = 0.64-0.94, p = 0.009) and the disease-free survival (DFS) (HR = 1.25, 95% CI = 1.07-1.47, p = 0.005). Subgroup analyses based on tumour type found that high FOLR1 level was associated with poor OS in breast cancer (HR = 2.66, 95% CI = 1.54-4.59, p = 0.0005) and endometrial carcinoma (HR = 1.30, 95% CI = 1.05-1.61, p = 0.02). However, FOLR1 has relatively weakly correlation with gender, tumour size and chemotherapy. Additionally, overexpression of FOLR1 was correlated with grade, FIGO stage, vital status and nodule status. The present meta-analysis indicated that the high expression of FOLR1 is associated with the poor survival of cancer patients, which is helpful for the clinical decision-making process.

Development and characterization of folic acid-functionalized apoferritin as a delivery vehicle for epirubicin against MCF-7 breast cancer cells

Epirubicin (Epr) is an effective chemotherapeutic drug; however, the clinical amenability of Epr is limited by its highly toxic interaction with normal cells. This toxicity can be decreased by utilizing nanocarriers and targeted drug delivery systems. This work describes an approach for the delivery of Epr via encapsulation in the horse spleen apoferritin (HsAFr) cavity. The encapsulation was achieved by the disassembling of apoferritin into subunits at pH 2 followed by its reformation at pH 7.4 in the presence of Epr. The surface of HsAFr-encapsulated Epr was modified with folic acid (FA) for optimal targeting of breast cancer cells (MCF-7). The use of FA to functionalize HsAFr could enhance the cellular uptake efficiency via FA-receptor-mediated endocytosis. UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism (CD) and transmission electron microscopy (TEM) were utilized for structural characterization of the HsAFr-Epr and HsAFr-Epr-FA complexes. The comparison of the anti-cancer activities across the HsAFr-Epr-FA complex and the free Epr drug was performed using the MTT viability assay on MCF-7.

BRCA1 and BRCA2 mRNA-expression prove to be of clinical impact in ovarian cancer

BACKGROUND

Mutations in BRCA1 and BRCA2 are associated with better survival in ovarian cancer (OC) patients due to a better response to platinum-based chemotherapy. However, the impact of the BRCA1/2 mRNA-expression is not well characterized in OC.

PATIENTS AND METHODS

We investigated BRCA1/2 mRNA-expression in 12 non-neoplastic fallopian tubes and 201 epithelial OCs in relation to their clinical characteristics.

RESULTS

We found higher BRCA1/2 mRNA-expression in OCs compared to controls (P = 0.011, P < 0.001, respectively). BRCA1 mutated OCs exhibited lower BRCA1 (P = 0.014) but higher BRCA2 mRNA-expression (P = 0.001). Low BRCA1-expression was associated with favorable overall survival (OS) (P = 0.012) and low BRCA2-expression with better progression-free survival (PFS) and OS (P = 0.004, P = 0.001, respectively). A subgroup-analysis showed that this effect was confined only to the BRCA1-wildtype cancers. Cox-regression confirmed the prognostic significance of BRCA1-expression for OS (P = 0.028). Independency of the prognostic value of BRCA2-expression for PFS (P = 0.045) and OS (P = 0.015) was restricted to high-grade serous OCs. Fully platinum-sensitivity was characterized by lower BRCA1/2 mRNA-expression in BRCA1-wildtype cancers in comparison to platinum-refractory OC.

CONCLUSION

Our findings may reflect higher platinum-sensitivity due to reduced capacity of DNA damage repair in tissues with low BRCA1/2-expression. In this context, especially in BRCA-wildtype cancers both parameters could also be potential predictors for PARP-sensitivity.

A novel isolation method for cancer prognostic factors via the p53 pathway by a combination of in vitro and in silico analyses

Identifying new therapeutic target genes affecting the survival of patients with cancer is crucial for the development of new cancer therapies. Here, we developed a novel technology combining in vitro short hairpin RNA (shRNA) library screening and in silico analysis of the tumor transcriptome to identify prognostic factors via the p53 tumor-suppressor pathway. For initial screening, we screened 5,000 genes through selection of shRNAs in p53 wild-type tumor cells that altered sensitivity to the p53 activator actinomycin D (ActD) to identify p53 regulatory genes; shRNAs targeting 322 genes were obtained. Among these 322 genes, seven were prognostic factor candidates whose high expression increased ActD sensitivity while prolonging the survival period in patients with the p53 wild-type genotype. Conversely, we identified 33 genes as prognostic factor candidates among ActD-resistant genes related to a shortened survival period only in p53 wild-type tumors. These 40 genes had biological functions such as apoptosis, drug response, cell cycle checkpoint, and cell proliferation. The 40 genes selected by this method contained many known genes related to the p53 pathway and prognosis in patients with cancer. In summary, we developed an efficient screening method to identify p53-dependent prognostic factors with in vitro experimental data and database analysis.

Recent progress in single-cell cancer genomics

The advent of single-cell sequencing has been revolutionary to the field of cancer genomics. Perfectly suited to capture cancer's heterogeneous nature, single-cell analyses provide information bulk sequencing could never hope to uncover. Many mechanisms of cancer have yet to be fully understood, and single-cell approaches are showing promise in their abilities to uncover these mysteries. Here we focus on the most recent single-cell methods for cancer genomics, and how they are not only providing insights into the inner workings of cancer, but are also transforming individualized therapy and non-invasive monitoring and diagnosis.