The Epithelial-Mesenchymal Transition at the Crossroads between Metabolism and Tumor Progression.

The transition between epithelial and mesenchymal phenotype is emerging as a key determinant of tumor cell invasion and metastasis. It is a plastic process in which epithelial cells first acquire the ability to invade the extracellular matrix and migrate into the bloodstream via transdifferentiation into mesenchymal cells, a phenomenon known as epithelial-mesenchymal transition (EMT), and then reacquire the epithelial phenotype, the reverse process called mesenchymal-epithelial transition (MET), to colonize a new organ. During all metastatic stages, metabolic changes, which give cancer cells the ability to adapt to increased energy demand and to withstand a hostile new environment, are also important determinants of successful cancer progression. In this review, we describe the complex interaction between EMT and metabolism during tumor progression. First, we outline the main connections between the two processes, with particular emphasis on the role of cancer stem cells and LncRNAs. Then, we focus on some specific cancers, such as breast, lung, and thyroid cancer.

Optimization of Short RNA Aptamers for TNBC Cell Targeting.

Triple-negative breast cancer (TNBC) is an aggressive cancer with limited targeted therapies. RNA aptamers, suitably chemically modified, work for therapeutic purposes in the same way as antibodies. We recently generated 2'Fluoro-pyrimidines RNA-aptamers that act as effective recognition elements for functional surface signatures of TNBC cells. Here, we optimized three of them by shortening and proved the truncated aptamers as optimal candidates to enable active targeting to TNBC. By using prediction of secondary structure to guide truncation, we identified structural regions that account for the binding motifs of the full-length aptamers. Their chemical synthesis led to short aptamers with superb nuclease resistance, which specifically bind to TNBC target cells and rapidly internalize into acidic compartments. They interfere with the growth of TNBC cells as mammospheres, thus confirming their potential as anti-tumor agents. We propose sTN145, sTN58 and sTN29 aptamers as valuable tools for selective TNBC targeting and promising candidates for effective treatments, including therapeutic agents and targeted delivery nanovectors.

Oligonucleotide aptamers against tyrosine kinase receptors: Prospect for anticancer applications.

Transmembrane receptor tyrosine kinases (RTKs) play crucial roles in cancer cell proliferation, survival, migration and differentiation. Area of intense research is searching for effective anticancer therapies targeting these receptors and, to date, several monoclonal antibodies and small-molecule tyrosine kinase inhibitors have entered the clinic. However, some of these drugs show limited efficacy and give rise to acquired resistance. Emerging highly selective compounds for anticancer therapy are oligonucleotide aptamers that interact with their targets by recognizing a specific three-dimensional structure. Because of their nucleic acid nature, the rational design of advanced strategies to manipulate aptamers for both diagnostic and therapeutic applications is greatly simplified over antibodies. In this manuscript, we will provide a comprehensive overview of oligonucleotide aptamers as next generation strategies to efficiently target RTKs in human cancers.

Breakthroughs in Medicinal Chemistry: New Targets and Mechanisms, New Drugs, New Hopes-7.

Breakthroughs in Medicinal Chemistry [...].

Proneural-Mesenchymal Transition: Phenotypic Plasticity to Acquire Multitherapy Resistance in Glioblastoma.

Glioblastoma (GBM) is an extremely aggressive tumor of the central nervous system, with a prognosis of 12-15 months and just 3-5% of survival over 5 years. This is mainly because most patients suffer recurrence after treatment that currently consists in maximal resection followed by radio- and chemotherapy with temozolomide. The recurrent tumor shows a more aggressive behavior due to a phenotypic shift toward the mesenchymal subtype. Proneural-mesenchymal transition (PMT) may represent for GBM the equivalent of epithelial-mesenchymal transition associated with other aggressive cancers. In this review we frame this process in the high degree of phenotypic inter- and intra-tumor heterogeneity of GBM, which exists in different subtypes, each one characterized by further phenotypic variability in its stem-cell compartment. Under the selective pressure of different treatment agents PMT is induced. The mechanisms involved, as well as the significance of such event in the acquisition of a multitherapy resistance phenotype, are taken in consideration for future perspectives in new anti-GBM therapeutic options.

Breakthroughs in Medicinal Chemistry: New Targets and Mechanisms, New Drugs, New Hopes-6.

Breakthroughs in Medicinal Chemistry: New Targets and Mechanisms, New Drugs, New Hopes is a series of Editorials that is published on a biannual basis by the Editorial Board of the Medicinal Chemistry section of the journal Molecules [...].

The POZ/BTB and AT-Hook Containing Zinc Finger 1 (PATZ1) Transcription Regulator: Physiological Functions and Disease Involvement.

PATZ1 is a zinc finger protein, belonging to the POZ domain Krüppel-like zinc finger (POK) family of architectural transcription factors, first discovered in 2000 by three independent groups. Since that time accumulating evidences have shown its involvement in a variety of biological processes (i.e., embryogenesis, stemness, apoptosis, senescence, proliferation, T-lymphocyte differentiation) and human diseases. Here we summarize these studies with a focus on the PATZ1 emerging and controversial role in cancer, where it acts as either a tumor suppressor or an oncogene. Finally, we give some insight on clinical perspectives using PATZ1 as a prognostic marker and therapeutic target.

Inhibition of receptor signaling and of glioblastoma-derived tumor growth by a novel PDGFRß aptamer.

Platelet-derived growth factor receptor ß (PDGFRß) is a cell-surface tyrosine kinase receptor implicated in several cellular processes including proliferation, migration, and angiogenesis. It represents a compelling therapeutic target in many human tumors, including glioma. A number of tyrosine kinase inhibitors under development as antitumor agents have been found to inhibit PDGFRß. However, they are not selective as they present multiple tyrosine kinase targets. Here, we report a novel PDGFRß-specific antagonist represented by a nuclease-resistant RNA-aptamer, named Gint4.T. This aptamer is able to specifically bind to the human PDGFRß ectodomain (Kd: 9.6 nmol/l) causing a strong inhibition of ligand-dependent receptor activation and of downstream signaling in cell lines and primary cultures of human glioblastoma cells. Moreover, Gint4.T aptamer drastically inhibits cell migration and proliferation, induces differentiation, and blocks tumor growth in vivo. In addition, Gint4.T aptamer prevents PDGFRß heterodimerization with and resultant transactivation of epidermal growth factor receptor. As a result, the combination of Gint4.T and an epidermal growth factor receptor-targeted aptamer is better at slowing tumor growth than either single aptamer alone. These findings reveal Gint4.T as a PDGFRß-drug candidate with translational potential.

Multifunctional aptamer-miRNA conjugates for targeted cancer therapy.

While microRNAs (miRNAs) clearly regulate multiple pathways integral to disease development and progression, the lack of safe and reliable means for specific delivery of miRNAs to target tissues represents a major obstacle to their broad therapeutic application. Our objective was to explore the use of nucleic acid aptamers as carriers for cell-targeted delivery of a miRNA with tumor suppressor function, let-7g. Using an aptamer that binds to and antagonizes the oncogenic receptor tyrosine kinase Axl (GL21.T), here we describe the development of aptamer-miRNA conjugates as multifunctional molecules that inhibit the growth of Axl-expressing tumors. We conjugated the let-7g miRNA to GL21.T and demonstrate selective delivery to target cells, processing by the RNA interference machinery, and silencing of let-7g target genes. Importantly, the multifunctional conjugate reduced tumor growth in a xenograft model of lung adenocarcinoma. Therefore, our data establish aptamer-miRNA conjugates as a novel tool for targeted delivery of miRNAs with therapeutic potential.

Subtype Transdifferentiation in Human Cancer: The Power of Tissue Plasticity in Tumor Progression.

The classification of tumors into subtypes, characterized by phenotypes determined by specific differentiation pathways, aids diagnosis and directs therapy towards targeted approaches. However, with the advent and explosion of next-generation sequencing, cancer phenotypes are turning out to be far more heterogenous than initially thought, and the classification is continually being updated to include more subtypes. Tumors are indeed highly dynamic, and they can evolve and undergo various changes in their characteristics during disease progression. The picture becomes even more complex when the tumor responds to a therapy. In all these cases, cancer cells acquire the ability to transdifferentiate, changing subtype, and adapt to changing microenvironments. These modifications affect the tumor's growth rate, invasiveness, response to treatment, and overall clinical behavior. Studying tumor subtype transitions is crucial for understanding tumor evolution, predicting disease outcomes, and developing personalized treatment strategies. We discuss this emerging hallmark of cancer and the molecular mechanisms involved at the crossroads between tumor cells and their microenvironment, focusing on four different human cancers in which tissue plasticity causes a subtype switch: breast cancer, prostate cancer, glioblastoma, and pancreatic adenocarcinoma.

Mechanism of Action of Lactic Acid on Histones in Cancer.

Significance: Metabolic end products and intermediates can exert signaling functions as chemical sources for histone posttranslational modifications, which remodel chromatin and affect gene expression. Among them, lactic acid is responsible for histone lactylation, a recently discovered histone mark that occurs in high lactate conditions, such as those resulting from the Warburg effect in cancer cells. Recent Advances: Late-breaking studies have advanced the knowledge on the mechanisms involved in histone lactylation, requiring independent nonenzyme and enzyme-dependent reactions, which is emerging as an important hallmark of cancer cells linking metabolic changes to gene expression reprogramming. Critical Issues: In this study, we give an overview about this new epigenetic modification, focusing on its mechanism of action in tumors and tumor microenvironment. Future Directions: Further investigation on the competition mechanism between lactylation and acetylation, as well as on the mechanisms by which lactate fluctuation can control a specific gene set in a given tissue, is needed in the coming years to exploit new anticancer therapeutic approaches. Antioxid. Redox Signal. 40, 236-249.

Bispecific aptamer-decorated and light-triggered nanoparticles targeting tumor and stromal cells in breast cancer derived organoids: implications for precision phototherapies.

BACKGROUND: Based on the established role of cancer-stroma cross-talk in tumor growth, progression and chemoresistance, targeting interactions between tumor cells and their stroma provides new therapeutic approaches. Dual-targeted nanotherapeutics selectively acting on both tumor and stromal cells may overcome the limits of tumor cell-targeting single-ligand nanomedicine due to the complexity of the tumor microenvironment. METHODS: Gold-core/silica-shell nanoparticles embedding a water-soluble iridium(III) complex as photosensitizer and luminescent probe (Iren-AuSiO2_COOH) were efficiently decorated with amino-terminated EGFR (CL4) and PDGFRß (Gint4.T) aptamers (Iren-AuSiO2_Aptamer). The targeting specificity, and the synergistic photodynamic and photothermal effects of either single- and dual-aptamer-decorated nanoparticles have been assessed by confocal microscopy and cell viability assays, respectively, on different human cell types including mesenchymal subtype triple-negative breast cancer (MES-TNBC) MDA-MB-231 and BT-549 cell lines (both EGFR and PDGFRß positive), luminal/HER2-positive breast cancer BT-474 and epidermoid carcinoma A431 cells (only EGFR positive) and adipose-derived mesenchymal stromal/stem cells (MSCs) (only PDGFRß positive). Cells lacking expression of both receptors were used as negative controls. To take into account the tumor-stroma interplay, fluorescence imaging and cytotoxicity were evaluated in preclinical three-dimensional (3D) stroma-rich breast cancer models. RESULTS: We show efficient capability of Iren-AuSiO2_Aptamer nanoplatforms to selectively enter into target cells, and kill them, through EGFR and/or PDGFRß recognition. Importantly, by targeting EGFR+ tumor/PDGFRß+ stromal cells in the entire tumor bulk, the dual-aptamer-engineered nanoparticles resulted more effective than unconjugated or single-aptamer-conjugated nanoparticles in either 3D spheroids cocultures of tumor cells and MSCs, and in breast cancer organoids derived from pathologically and molecularly well-characterized tumors. CONCLUSIONS: Our study proposes smart, novel and safe multifunctional nanoplatforms simultaneously addressing cancer-stroma within the tumor microenvironment, which are: (i) actively delivered to the targeted cells through highly specific aptamers; (ii) localized by means of their luminescence, and (iii) activated via minimally invasive light, launching efficient tumor death, thus providing innovative precision therapeutics. Given the unique features, the proposed dual targeted nanoformulations may open a new door to precision cancer treatment.

Correction: Ibarra et al. Selective Photo-Assisted Eradication of Triple-Negative Breast Cancer Cells through Aptamer Decoration of Doped Conjugated Polymer Nanoparticles. Pharmaceutics 2022, 14, 626.

In the original publication [...].

The isolectin IB4 binds RET receptor tyrosine kinase in microglia.

Ret receptor tyrosine kinase is the signaling component of the receptor complex for the family ligands of the glial cell line-derived neurotrophic factor (GDNF). Ret is involved in the development of enteric nervous system, of sympathetic, parasympathetic, motor and sensory neurons, and it is necessary for the post-natal maintenance of dopaminergic neurons. Ret expression has been as well demonstrated on microglia and several evidence indicate that GDNF regulates not only neuronal survival and maturation but also certain functions of microglia in the brain. Here, we demonstrated that the plant lectin Griffonia (Bandeiraea) simplicifolia lectin I, isolectin B4 (IB4), commonly used as a microglial marker in the brain, binds to the glycosylated extracellular domain of Ret on the surface of living NIH3T3 fibroblasts cells stably transfected with Ret as well as in adult rat brain as revealed by immunoblotting. Furthermore, confocal immunofluorescence analysis demonstrated a clear overlap in staining between pRet and IB4 in primary microglia cultures as well as in adult rat sections obtained from control or post-ischemic brain after permanent middle artery occlusion (pMCAO). Interestingly, IB4 staining identified activated or ameboid Ret-expressing microglia under ischemic conditions. Collectively, our data indicate Ret receptor as one of the IB4-reactive glycoconjugate accounting for the IB4 stain in microglia under physiological and ischemic conditions.

Electrochemical detection of miRNA-222 by use of a magnetic bead-based bioassay.

MicroRNAs (miRNAs, miRs) are naturally occurring small RNAs (approximately 22 nucleotides in length) that have critical functions in a variety of biological processes, including tumorigenesis. They are an important target for detection technology for future medical diagnostics. In this paper we report an electrochemical method for miRNA detection based on paramagnetic beads and enzyme amplification. In particular, miR 222 was chosen as model sequence, because of its involvement in brain, lung, and liver cancers. The proposed bioassay is based on biotinylated DNA capture probes immobilized on streptavidin-coated paramagnetic beads. Total RNA was extracted from the cell sample, enriched for small RNA, biotinylated, and then hybridized with the capture probe on the beads. The beads were then incubated with streptavidin-alkaline phosphatase and exposed to the appropriate enzymatic substrate. The product of the enzymatic reaction was electrochemically monitored. The assay was finally tested with a compact microfluidic device which enables multiplexed analysis of eight different samples with a detection limit of 7 pmol L(-1) and RSD = 15 %. RNA samples from non-small-cell lung cancer and glioblastoma cell lines were also analyzed.

Targeting Axl with an high-affinity inhibitory aptamer.

Axl is a tyrosine kinase receptor that was first identified as a transforming gene in human myeloid leukemia. Recent converging evidence suggests its implication in cancer progression and invasion for several solid tumors, including lung, breast, brain, thyroid, and pancreas. In the last decade, Axl has thus become an attractive target for therapeutic development of more aggressive cancers. An emerging class of therapeutic inhibitors is now represented by short nucleic acid aptamers. These molecules act as high affinity ligands with several advantages over conventional antibodies for their use in vivo, including their small size and negligible immunogenicity. Furthermore, these molecules can easily form conjugates able to drive the specific delivery of interfering RNAs, nanoparticles, or chemotherapeutics. We have thus generated and characterized a selective RNA-based aptamer, GL21.T that binds the extracellular domain of Axl at high affinity (12 nmol/l) and inhibits its catalytic activity. GL21.T blocked Axl-dependent transducing events in vitro, including Erk and Akt phosphorylation, cell migration and invasion, as well as in vivo lung tumor formation in mice xenografts. In this respect, the GL21.T aptamer represents a promising therapeutic molecule for Axl-dependent cancers whose importance is highlighted by the paucity of available Axl-specific inhibitory molecules.

Aptamer-Based Strategies to Boost Immunotherapy in TNBC.

The immune system (IS) may play a crucial role in preventing tumor development and progression, leading, over the last years, to the development of effective cancer immunotherapies. Nevertheless, immune evasion, the capability of tumors to circumvent destructive host immunity, remains one of the main obstacles to overcome for maximizing treatment success. In this context, promising strategies aimed at reshaping the tumor immune microenvironment and promoting antitumor immunity are rapidly emerging. Triple-negative breast cancer (TNBC), an aggressive breast cancer subtype with poor outcomes, is highly immunogenic, suggesting immunotherapy is a viable strategy. As evidence of this, already, two immunotherapies have recently become the standard of care for patients with PD-L1 expressing tumors, which, however, represent a low percentage of patients, making more active immunotherapeutic approaches necessary. Aptamers are short, highly structured, single-stranded oligonucleotides that bind to their protein targets at high affinity and specificity. They are used for therapeutic purposes in the same way as monoclonal antibodies; thus, various aptamer-based strategies are being actively explored to stimulate the IS's response against cancer cells. The aim of this review is to discuss the potential of the recently reported aptamer-based approaches to boost the IS to fight TNBC.

The IL13α 2R paves the way for anti-glioma nanotherapy.

Glioblastoma (GBM) is one of the most aggressive (grade IV) gliomas characterized by a high rate of recurrence, resistance to therapy and a grim survival prognosis. The long-awaited improvement in GBM patients' survival rates essentially depends on advances in the development of new therapeutic approaches. Recent preclinical studies show that nanoscale materials could greatly contribute to the improvement of diagnosis and management of brain cancers. In the current review, we will discuss how specific features of glioma pathobiology can be employed for designing efficient targeting approaches. Moreover, we will summarize the main evidence for the potential of the IL-13R alpha 2 receptor (IL13α2R) targeting in GBM early diagnosis and experimental therapy.

Inhibition of Bone Marrow-Mesenchymal Stem Cell-Induced Carbonic Anhydrase IX Potentiates Chemotherapy Efficacy in Triple-Negative Breast Cancer Cells.

Conventional chemotherapy represents the main systemic treatment used for triple-negative breast cancer (TNBC) patients, although many of them develop drug resistance. The hypoxic TME is the crucial driver in the onset of insensitivity to chemotherapy. In this research, we elucidated the role played by bone marrow-derived mesenchymal stem cells (BM-MSCs) in reducing cisplatin effects in TNBC. BT-549 and MDA-MB-231 cells, grown under hypoxic conditions in the presence of conditioned medium obtained from BM-MSCs (CM-MSCs), showed a strong cisplatin insensitivity and increased expression levels of carbonic anhydrase IX (CA IX). Therefore, we inhibited CM-MSC-induced CA IX by SLC-0111 to potentiate chemotherapy efficacy in TNBC cells. Our results showed that CM-MSCs under hypoxic conditions caused an increase in the ability of TNBC cells to form vascular structures, migrate and invade Matrigel. Cell treatment with cisplatin plus SLC-0111 was able to block these mechanisms, as well as the signaling pathways underlying them, such as p-AKT, p-ERK, CD44, MMP-2, vimentin, ß-catenin, and N-cadherin, more effectively than treatment with single agents. In addition, a significant enhancement of apoptosis assessed by annexin V, caspase-3 expression and activity was also shown. Taken together, our results demonstrated the possibility, through CA IX inhibition, of returning TNBC cells to a more chemosensitive state.

Tissue Inhibitor of Metalloproteinases-1 Overexpression Mediates Chemoresistance in Triple-Negative Breast Cancer Cells.

Triple-negative breast cancer (TNBC) is among the most aggressive breast cancer subtypes. Despite being initially responsive to chemotherapy, patients develop drug-resistant and metastatic tumors. Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a secreted protein with a tumor suppressor function due to its anti-proteolytic activity. Nevertheless, evidence indicates that TIMP-1 binds to the CD63 receptor and activates noncanonical oncogenic signaling in several cancers, but its role in mediating TNBC chemoresistance is still largely unexplored. Here, we show that mesenchymal-like TNBC cells express TIMP-1, whose levels are further increased in cells generated to be resistant to cisplatin (Cis-Pt-R) and doxorubicin (Dox-R). Moreover, public dataset analyses indicate that high TIMP-1 levels are associated with a worse prognosis in TNBC subjected to chemotherapy. Knock-down of TIMP-1 in both Cis-Pt-R and Dox-R cells reverses their resistance by inhibiting AKT activation. Consistently, TNBC cells exposed to recombinant TIMP-1 or TIMP-1-enriched media from chemoresistant cells, acquire resistance to both cisplatin and doxorubicin. Importantly, released TIMP-1 reassociates with plasma membrane by binding to CD63 and, in the absence of CD63 expression, TIMP-1-mediated chemoresistance is blocked. Thus, our results identify TIMP-1 as a new biomarker of TNBC chemoresistance and lay the groundwork for evaluating whether blockade of TIMP-1 signal is a viable treatment strategy.