Application of aptamers in treatment and diagnosis of leukemia

Trends and frontiers in signal amplification for aptamer-based tumor detection: A bibliometric analysis

BACKGROUND

Malignant tumors are one of the leading causes of death worldwide, imposing a substantial economic and social burden. Early detection is the key to improving cure rates and reducing mortality rates, which requires the development of sensitive early detection technologies. Signal amplification techniques play a crucial role in aptamer-based early detection of tumors and are increasingly garnering attention from researchers.

AIM

To investigate the current research status, developmental trajectories, and hotspots in signal amplification for aptamer-based tumor detection through bibliometric analysis.

METHODS

English publications pertaining to signal amplification in aptamer-based tumor detection were retrieved from the Web of Science Core Collection database. VOSviewer and CiteSpace software were employed to analyze various information within this field, including countries, institutions, authors, co-cited authors, journals, co-cited journals, cited references, and keywords.

RESULTS

A total of 757 publications were included in this study. China accounted for 85.47% of all publications, with Nanjing University (China) emerging as the institution with the highest publication output. The most influential authors and journals were Hasanzadeh M. from Iran and "Biosensors and Bioelectronics", respectively. Exosomes and carcinoembryonic antigen (CEA) stood out as the most researched tumor-related molecules. Currently, the predominant signal amplification technique, nanomaterial, and signal transduction method were identified as hybridization chain reactions, gold nanoparticles, and electrochemical methods, respectively. Over the past 3 years, exosomes, CEA, electrochemical biosensors, and nanosheets have emerged as research hotspots, exhibiting a robust burst of intensity.

CONCLUSION

This study is the first bibliometric analysis of literature on signal amplification in aptamer-based tumor detection and elucidates the current status, hotspots, and prospective research directions within this realm. Additionally, it provides an important reference for researchers.

Structure-based investigation of a DNA aptamer targeting PTK7 reveals an intricate 3D fold guiding functional optimization

DNA aptamers have emerged as novel molecular tools in disease theranostics owing to their high binding affinity and specificity for protein targets, which rely on their ability to fold into distinctive three-dimensional (3D) structures. However, delicate atomic interactions that shape the 3D structures are often ignored when designing and modeling aptamers, leading to inefficient functional optimization. Challenges persist in determining high-resolution aptamer-protein complex structures. Moreover, the experimentally determined 3D structures of DNA molecules with exquisite functions remain scarce. These factors impede our comprehension and optimization of some important DNA aptamers. Here, we performed a streamlined solution NMR-based structural investigation on the 41-nt sgc8c, a prominent DNA aptamer used to target membrane protein tyrosine kinase 7, for cancer theranostics. We show that sgc8c prefolds into an intricate three-way junction (3WJ) structure stabilized by long-range tertiary interactions and extensive base-base stackings. Delineated by NMR chemical shift perturbations, site-directed mutagenesis, and 3D structural information, we identified essential nucleotides constituting the key functional elements of sgc8c that are centralized at the core of 3WJ. Leveraging the well-established structure-function relationship, we efficiently engineered two sgc8c variants by modifying the apical loop and introducing L-DNA base pairs to simultaneously enhance thermostability, biostability, and binding affinity for both protein and cell targets, a feat not previously attained despite extensive efforts. This work showcases a simplified NMR-based approach to comprehend and optimize sgc8c without acquiring the complex structure, and offers principles for the sophisticated structure-function organization of DNA molecules.

Emerging Biohybrids of Aptamer-Based Nano-Biosensing Technologies for Effective Early Cancer Detection

Cancer is a leading global cause of mortality, which underscores the imperative of early detection for improved patient outcomes. Biorecognition molecules, especially aptamers, have emerged as highly effective tools for early and accurate cancer cell identification. Aptamers, with superior versatility in synthesis and modification, offer enhanced binding specificity and stability compared with conventional antibodies. Hence, this article reviews diagnostic strategies employing aptamer-based biohybrid nano-biosensing technologies, focusing on their utility in detecting cancer biomarkers and abnormal cells. Recent developments include the synthesis of nano-aptamers using diverse nanomaterials, such as metallic nanoparticles, metal oxide nanoparticles, carbon-derived substances, and biohybrid nanostructures. The integration of these nanomaterials with aptamers significantly enhances sensitivity and specificity, promising innovative and efficient approaches for cancer diagnosis. This convergence of nanotechnology with aptamer research holds the potential to revolutionize cancer treatment through rapid, accurate, and non-invasive diagnostic methods.

Breaking Barriers: Nucleic Acid Aptamers in Gastrointestinal (GI) Cancers Therapy

Conventional cancer therapies can have significant adverse effects as they are not targeted to cancer cells and may damage healthy cells. Single-stranded oligonucleotides assembled in a particular architecture, known as aptamers, enable them to attach selectively to target areas. Usually, they are created by Systematic Evolution of Ligand by Exponential enrichment (SELEX), and they go through a rigorous pharmacological revision process to change their therapeutic half-life, affinity, and specificity. They could thus offer a viable substitute for antibodies in the targeted cancer treatment market. Although aptamers can be a better choice in some situations, antibodies are still appropriate for many other uses. The technique of delivering aptamers is simple and reasonable, and the time needed to manufacture them is relatively brief. Aptamers do not require animals or an immune response to be produced, in contrast to antibodies. When used as a medication, aptamers can directly suppress tumor cells. As an alternative, they can be included in systems for targeted drug delivery that administer medications specifically to tumor cells while reducing toxicity to healthy cells. The most recent and cutting-edge methods for treating gastrointestinal (GI) tract cancer with aptamers will be covered in this review, with a focus on targeted therapy as a means of conquering resistance to traditional medicines.

Quantitative Evaluation of a Multimodal Aptamer-Targeted Long-Circulating Polymer for Tumor Targeting

Aptamers are promising targeting agents for imaging and therapy of numerous diseases, including cancer. However, a significant shortcoming of aptamers is their poor stability and fast excretion, limiting their application in vivo. Common strategies to overcome these challenges is to chemically modify aptamers in order to increase their stability and/or to apply formulation technologies such as conjugating them to polymers or nanocarriers in order to increase their circulation half-life. This is expected to result in improved cellular uptake or retention to passively targeted nanomedicines. Herein, we report a modular conjugation strategy based on click chemistry between functionalized tetrazines and trans-cyclooctene (TCO), for the modification of high molecular weight hyperbranched polyglycerol (HPG) with sgc8 aptamer, fluorescent dyes, and ¹¹¹In. Our data indicate strong affinity of sgc8 against a range of solid tumor-derived cell lines that have previously not been tested with this aptamer. Nevertheless, nonspecific uptake of scrambled ssDNA-functionalized HPG in cells highlights inherent challenges of aptamer-targeted probes that remain to be solved for clinical translation. We validate HPG-sgc8 as a nontoxic nanoprobe with high affinity against MDA-MB-468 breast and A431 lung cancer cells and show significantly increased plasma stability compared to free sgc8. In vivo quantitative SPECT/CT imaging indicates EPR-mediated tumor uptake of HPG-sgc8 and nontargeted or scrambled ssDNA-conjugated HPG but no statistically significant difference between these formulations in terms of total tumor uptake or retention. Our study emphasizes the need for stringent controls and quantification in the evaluation of aptamer-targeted probes. For this purpose, our versatile synthesis strategy provides a simple approach for the design and evaluation of long-circulating aptamer-conjugated nanoformulations.

Advances in aptamer-mediated targeted delivery system for cancer treatment

Aptamers with high affinity and specificity for certain targets have rapidly become a novel class of targeted ligands applicated in drug delivery. Based on the excellent characteristics of aptamers, different aptamer-mediated drug delivery systems have been developed, including aptamer-drug conjugate (ApDC), aptamer-siRNA, and aptamer-functionalized nanoparticle systems for the effective treatment of cancer, which can reduce potential toxicity and improve therapeutic efficacy. In this review, we summarize the recent progress of aptamer-mediated delivery systems in cancer therapy, and discuss the application prospects and existing problems of innovative approaches based on aptamer therapy. Overall, this review aims to better understand the current aptamer-based targeted delivery applications through in-depth analysis to improve efficacy and develop new therapeutic methods which can ultimately improve treatment outcomes for cancer patients.

Study on Sgc8 Aptamer-mediated Nucleic Acid Nanomaterial-doxorubicin Complex for Tumor Targeted Therapy

Chemotherapy is one of the most important treatments for malignant cancers, but most chemotherapeutic drugs are poorly targeted, highly toxic and expensive, resulting in unsatisfactory treatment results for cancer patients. Therefore, intelligent drug delivery platforms are needed to be explored urgently to enhance drug treatment and reduce toxicity on normal cells. Nucleic acid nanomaterials are a class of nanomaterials developed on the basis of the "base complementary pairing principle", which have the advantages of good programmability, high stability, good biocompatibility, and strong targeting. Herein, we present a simple Sgc8 aptamer-modified nucleic acid nanomaterial (Sgc8NM) for the targeted delivery of Doxorubicin (Dox), a widely used chemotherapy drug in clinic. Studies have shown the Sgc8NM-Dox performed a precise treatment effect on target cells and low toxicity on non-target cells, providing a new strategy for the potential application of nanocomposite drugs in targeted cancer delivery.

Targeted-Lymphoma Drug Delivery System Based on the Sgc8-c Aptamer

Aptamers are emerging as a promising new class of functional nucleic acids because they can specifically bind to any target with high affinity and be easily modified chemically with different pharmacophoric subunits for therapy. The truncated aptamer, Sgc8-c, binds to tyrosine-protein kinase-like 7 receptor, a promising cancer therapeutic target, allowing the recognition of haemato-oncological malignancies, among others. We have previously developed aptamer-drug conjugates by chemical synthesis, hybridizing Sgc8-c and dasatinib, a drug proposed for lymphoma chemotherapy. One of the best-characterised Sgc8-c-dasatinib hybrids, namely Sgc8-c-carb-da, was capable of releasing dasatinib at an endosomal-pH. Herein, we probed the therapeutic potential of this aptamer-drug conjugate. Sgc8-c-carb-da specifically inhibited murine A20 B lymphocyte growth and produced cell death, mainly by late apoptosis and necrosis. In addition, Sgc8-c-carb-da generated an arrest in cell proliferation, with a cell cycle arrest in the Sub-G1-peak. The mitochondrial potential was altered accordingly to these pathways. Moreover, using an in vitro cell-targeting assay that mimics in vivo conditions, we showed that Sgc8-c-carb-da displayed higher (2.5-fold) cytotoxic effects than dasatinib. These findings provide proof-of-concept of the therapeutic value of Sgc8-c-carb-da for lymphoma, creating new opportunities for the chemical synthesis of targeted biotherapeutics.

Nanotechnology-based diagnostics and therapeutics in acute lymphoblastic leukemia: a systematic review of preclinical studies

Background: Leukemia is a malignant disease that threatens human health and life. Nano-delivery systems improve drug solubility, bioavailability, and blood circulation time, and release drugs selectively at desired sites using targeting or sensing strategies. As drug carriers, they could improve therapeutic outcomes while reducing systemic toxicity. They have also shown promise in improving leukemia detection and diagnosis. The study aimed to assess the potential of nanotechnology-based diagnostics and therapeutics in preclinical human acute lymphoblastic leukemia (h-ALL). Methods: We performed a systematic search through April 2022. Articles written in English reporting the toxicity, efficacy, and safety of nanotechnology-based drugs (in the aspect of treatment) and specificity, limit of detection (LOD), or sensitivity (in the aspect of the detection field) in preclinical h-ALL were included. The study was performed according to PRISMA instructions. The methodological quality was assessed using the QualSyst tool. Results: A total of 63 original articles evaluating nanotechnology-based therapeutics and 35 original studies evaluating nanotechnology-based diagnostics were included in this review. As therapeutics in ALL, nanomaterials offer controlled release, targeting or sensing ligands, targeted gene therapy, photodynamic therapy and photothermic therapy, and reversal of multidrug-resistant ALL. A narrative synthesis of studies revealed that nanoparticles improve the ratio of efficacy to the toxicity of anti-leukemic drugs. They have also been developed as a vehicle for biomolecules (such as antibodies) that can help detect and monitor leukemic biomarkers. Therefore, nanomaterials can help with early diagnostics and personalized treatment of ALL. Conclusion: This review discussed nanotechnology-based preclinical strategies to achieve ALL diagnosis and therapy advancement. This involves modern drug delivery apparatuses and detection devices for prompt and targeted disease diagnostics. Nonetheless, we are yet in the experimental phase and investigational stage in the field of nanomedicine, with many features remained to be discovered as well as numerous problems to be solved.

The Research Advances of Aptamers in Hematologic Malignancies

Currently, research for hematological malignancies is very intensive, with many breakthroughs. Among them, aptamer-based targeted therapies could be counted. Aptamer is a targeting tool with many unique advantages (easy synthesis, low toxicity, easy modification, low immunogenicity, nano size, long stability, etc.), therefore many experts screened corresponding aptamers in various hematological malignancies for diagnosis and treatment. In this review, we try to summarize and provide the recent progress of aptamer research in the diagnosis and treatment of hematologic malignancies. Until now, 29 aptamer studies were reported in hematologic malignancies, of which 12 aptamers were tested in vivo and the remaining 17 aptamers were only tested in vitro. In this case, 11 aptamers were combined with chemotherapeutic drugs for the treatment of hematologic malignancies, 4 aptamers were used in combination with nanomaterials for the diagnosis and treatment of hematologic malignancies, and some studies used aptamers for the targeted transportation of siRNA and miRNA for targeted therapeutic effects. Their research provides multiple approaches to achieve more targeted goals. These findings show promising and encouraging future for both hematological malignancies basic and clinical trials research.

Fabrication of Au/Fe3O4/RGO based aptasensor for measurement of miRNA-128, a biomarker for acute lymphoblastic leukemia (ALL)

Due to their high sensitivity, simplicity, portability, self-contained, and low cost, the development of electrochemical biosensors is a beneficial way to diagnose and anticipate many types of cancers. An electrochemical nanocomposite-based aptasensor is fabricated for the determination of miRNA-128 concentration as the acute lymphoblastic leukemia (ALL) biomarker for the first time. The aptamer chains were immobilized on the surface of the glassy carbon electrode (GCE) through gold nanoparticles/magnetite/reduced graphene oxide (AuNPs/Fe3O4/RGO). Fast Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM) were used to characterize synthesized nanomaterials. Cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were used to characterize the modified GCE in both label-free and labeled methods. The results indicate that the modified working electrode has high selectivity and for miRNA-128 over other biomolecules. The hexacyanoferrate redox system typically operated at around 0.3 V (vs. Ag/AgCl), and the methylene blue redox system ran at about 0 V, were used as an electrochemical probe. The detection limit and linear detection range for hexacyanoferrate and methylene blue are 0.05346 fM, 0.1-0.9 fM, and 0.005483 fM, 0.01-0.09 fM, respectively. The stability and diffusion control analyses were performed as well. In both label-free and labeled methods, the modified electron showed high selectivity for miRNA-128. The use of methylene blue as a safer redox mediator caused miRNA-128 to be detected with greater accuracy at low potentials in PBS media. The findings also show the substantial improvement in detection limit and linearity by using reduced graphene oxide-magnetite-gold nanoparticles that can be verified by comparing with previous studies on the detection of other miRNAs.

Delivery strategies in treatments of leukemia

Leukemia is a hematological malignancy associated with the uncontrolled proliferation of mutant progenitors, suppressing the production of normal blood cells. Current treatments, including chemotherapy, radiotherapy, and immunotherapy, still lead to unsatisfactory results with a 5 year survival rate of only 30-50%. The poor prognosis is related to both disease relapse and treatment-associated toxicity. Delivery strategies can improve the in vivo pharmacokinetics of drugs, navigating the therapeutics to target cells or the tumor microenvironment and reversing drug resistance, which maximizes tumor elimination and alleviates systematic adverse effects. This review discusses available FDA-approved anti-leukemia drugs and therapies with a focus on the advances in the development of anti-leukemia drug delivery systems. Additionally, challenges in clinical translation of the delivery strategies and future research opportunities in leukemia treatment are also included.

Progress in cancer drug delivery based on AS1411 oriented nanomaterials

Targeted cancer therapy has become one of the most important medical methods because of the spreading and metastatic nature of cancer. Based on the introduction of AS1411 and its four-chain structure, this paper reviews the research progress in cancer detection and drug delivery systems by modifying AS1411 aptamers based on graphene, mesoporous silica, silver and gold. The application of AS1411 in cancer treatment and drug delivery and the use of AS1411 as a targeting agent for the detection of cancer markers such as nucleoli were summarized from three aspects of active targeting, passive targeting and targeted nucleic acid apharmers. Although AS1411 has been withdrawn from clinical trials, the research surrounding its structural optimization is still very popular. Further progress has been made in the modification of nanoparticles loaded with TCM extracts by AS1411.

New substrates and determinants for tRNA recognition of RNA methyltransferase DNMT2/TRDMT1

Methylation is a common post-transcriptional modification of tRNAs, particularly in the anticodon loop region. The cytosine 38 (C38) in tRNAs, such as tRNAAsp-GUC, tRNAGly-GCC, tRNAVal-AAC, and tRNAGlu-CUC, can be methylated by human DNMT2/TRDMT1 and some homologs found in bacteria, plants, and animals. However, the substrate properties and recognition mechanism of DNMT2/TRDMT1 remain to be explored. Here, taking into consideration common features of the four known substrate tRNAs, we investigated methylation activities of DNMT2/TRDMT1 on the tRNAGly-GCC truncation and point mutants, and conformational changes of mutants. The results demonstrated that human DNMT2/TRDMT1 preferred substrate tRNAGly-GCC in vitro. L-shaped conformation of classical tRNA could be favourable for DNMT2/TRDMT1 activity. The complete sequence and structure of tRNA were dispensable for DNMT2/TRDMT1 activity, whereas T-arm was indispensable to this activity. G19, U20, and A21 in D-loop were identified as the important bases for DNMT2/TRDMT1 activity, while G53, C56, A58, and C61 in T-loop were found as the critical bases. The conserved CUXXCAC sequence in the anticodon loop was confirmed to be the most critical determinant, and it could stabilize C38-flipping to promote C38 methylation. Based on these tRNA properties, new substrates, tRNAVal-CAC and tRNAGln-CUG, were discovered in vitro. Moreover, a single nucleotide substitute, U32C, could convert non-substrate tRNAAla-AGC into a substrate for DNMT2/TRDMT1. Altogether, our findings imply that DNMT2/TRDMT1 relies on a delicate network involving both the primary sequence and tertiary structure of tRNA for substrate recognition.

Advances in Electrochemical and Acoustic Aptamer-Based Biosensors and Immunosensors in Diagnostics of Leukemia

Early diagnostics of leukemia is crucial for successful therapy of this disease. Therefore, development of rapid, sensitive, and easy-to-use methods for detection of this disease is of increased interest. Biosensor technology is challenged for this purpose. This review includes a brief description of the methods used in current clinical diagnostics of leukemia and provides recent achievements in sensor technology based on immuno- and DNA aptamer-based electrochemical and acoustic biosensors. The comparative analysis of immuno- and aptamer-based sensors shows a significant advantage of DNA aptasensors over immunosensors in the detection of cancer cells. The acoustic technique is of comparable sensitivity with those based on electrochemical methods; moreover, it is label-free and provides straightforward evaluation of the signal. Several examples of sensor development are provided and discussed.

Pancreatic Adenocarcinoma: Unconventional Approaches for an Unconventional Disease

This review highlights current treatments, limitations, and pitfalls in the management of pancreatic cancer and discusses current research in novel targets and drug development to overcome these clinical challenges. We begin with a review of the clinical landscape of pancreatic cancer, including genetic and environmental risk factors, as well as limitations in disease diagnosis and prevention. We next discuss current treatment paradigms for pancreatic cancer and the shortcomings of targeted therapy in this disease. Targeting major driver mutations in pancreatic cancer, such as dysregulation in the KRAS and TGFβ signaling pathways, have failed to improve survival outcomes compared with nontargeted chemotherapy; thus, we describe new advances in therapy such as Ras-binding pocket inhibitors. We then review next-generation approaches in nanomedicine and drug delivery, focusing on preclinical advancements in novel optical probes, antibodies, small-molecule agents, and nucleic acids to improve surgical outcomes in resectable disease, augment current therapies, expand druggable targets, and minimize morbidity. We conclude by summarizing progress in current research, identifying areas for future exploration in drug development and nanotechnology, and discussing future prospects for management of this disease.

Fabrication of aptamer modified TiO2 nanofibers for specific capture of circulating tumor cells

Herein, we developed an inexpensive titanium dioxide (TiO₂) nanofiber substrate for efficient and selective capture of circulating tumor cells (CTCs) from mimic patients' samples. The TiO₂ nanofiber substrates were fabricated by electrospinning in combination with the calcination process. The surface of nanofiber substrates was modified with the anti-adhesion molecule, bovine serum albumin (BSA) and the nucleolin aptamer AS1411, wherein, aptamer AS1411 specifically binds to the nucleolin protein overexpressed on the membrane surface of cancer cells. The formed TiO₂ nanofiber substrates exhibited high efficacy and specificity to capture nucleolin positive cells through synergistic topographic interactions. Using the rare number of cell capture experiments, the capture efficiency of up to 75 % was achieved on the surface of the nanofiber substrate for rare number target cells spiked in the white blood cells (WBCs) from 1 mL whole blood samples. In conclusion, this study highlighted the potential of the TiO₂-BSA-biotin-AS1411 nanofiber substrate as a highly efficient platform to realize the selective and specific capture of rare CTCs in the clinical settings.

A label-free aptasensor for highly sensitive detection of homocysteine based on gold nanoparticles

In the present study, an original electrode fabrication approach was devised to create a label free sensitive electrochemical aptasensor for the detection of Homocysteine (Hcy) (Homocysteine signal was used for detection). To bind certain targets, synthetic oligonucleotides used as aptamers (APs) were specifically selected. Aptamers are substitutes for antibodies for analytical devices because of their sensitivity and high affinity. In this study, Hcy-Binding-Aptamer (HBA) was grafted onto the surface of Au nanoparticles/Glassy Carbon Electrode (Au/GCE) in order to create an aptasensor. The effects of buffer concentration, buffer type, interaction time, and aptamer concentration were investigated and optimized. In addition, Differential Pulse Voltammetry (DPV) was implemented to identify homocysteine. Favorable performance was achieved at a detection limit of 0.01 μM (S/N = 3) and linear range 0.05-20.0 μM. Furthermore, the fabricated aptasensor displayed desirable stability and reproducibility. The developed electrochemical aptasensor was found to have reasonable selectivity for the detection of homocysteine in the presence of cysteine and methionine. Analysis of real samples showed good ability of the proposed homocysteine biosensor to provide sensitive, quick, easy, and cost effective measurement of homocysteine in human blood serum and urine samples.

An Efficient Cell-Targeting Drug Delivery System Based on Aptamer-Modified Mesoporous Silica Nanoparticles

How to deliver chemotherapeutic drugs efficiently and selectively to tumor cells to improve therapeutic efficacy remains a difficult problem. We herein construct an efficient cell-targeting drug delivery system (Sgc8-MSN/Dox) based on aptamer-modified mesoporous silica nanoparticles that relies on the tumor-targeting ability of the aptamer Sgc8 to deliver doxorubicin (Dox) to leukemia cells in a targeted way, thereby improving therapeutic efficacy and reducing toxicity. In this work, Sgc8-MSN/Dox showed sustained Dox release, and they targeted and efficiently killed CCRF-CEM human acute T lymphocyte leukemia cells, suggesting potential as a cancer therapy.

Sgc8 aptamer targeted glutathione-responsive nanoassemblies containing Ara-C prodrug for the treatment of acute lymphoblastic leukemia

Cytarabine (Ara-C) is an essential medicine used in the clinical treatment of acute lymphoblastic leukemia. However, Ara-C suffers from high hydrophilicity, rapid plasma degradation and significant side effects. Thus, herein, to eliminate the limitations of Ara-C in the treatment of leukemia, Sgc8 aptamer targeting and glutathione (GSH)-responsive polymeric micelles (PCL-ss-Ara@Sgc8-BSA) were prepared. The prodrug was synthesized via covalent bond formation between acryloyl chloride-terminal PCL-ss-PCL and Ara-C, and surface decoration with Sgc8-bovine serum albumin (Sgc8-BSA). The obtained PCL-ss-Ara@Sgc8-BSA exhibited good GSH-responsive drug release behavior, obvious targetability and sufficient antitumor effect to acute lymphoblastic leukemia (ALL) cells (CCRF-CEM). A hemolysis test was further carried out to demonstrate that these polymeric micelles are safe to be administrated intravenously. Compared with free Ara-C, PCL-ss-Ara@Sgc8-BSA significantly enhanced tumor growth inhibition in mice bearing CCRF-CEM xenograft tumors, while causing little side effects, and improved the survival rate of CCRF-CEM tumor-bearing mice in vivo. Therefore, this new self-assembling small molecular prodrug equipped with Sgc8 targeting function is a potential treatment for the targeted therapy of acute lymphoblastic leukemia.

Nucleic Acid Aptamer: A Novel Potential Diagnostic and Therapeutic Tool for Leukemia

Leukemia immunotherapy has been dominant via using synthetic antibodies to target cluster of differentiation (CD) molecules, nevertheless inevitable cytotoxicity and immunogenicity would limit its development. Recently, increasing reports have focused on nucleic acid aptamers, a class of high-affinity nucleic acid ligands. Aptamers purportedly serve as “chemical antibodies”, have negligible cytotoxicity and low immunogenicity, and would be widely applied for the therapy and diagnosis of various diseases, especially leukemia. In the preclinical applications, nucleic acid aptamers have displayed the augmented specificity and selectivity via recognizing targets on leukemia cells based on unique three-dimensional conformations. As small molecules with nucleic acid characteristics, aptamers need to be chemically modified to resist nuclease degradation, renal clearance and improve binding affinities. Moreover, aptamers can be linked with neoteric detection techniques to enhance sensitivity and selectivity of diagnosis and therapy. In this review, we summarized aptamers’ preparation, chemical modification and conjugation, and discussed the application of aptamers in diagnosis and treatment of leukemia through highly specifically recognizing target molecules. Significantly, the application prospect of aptamers in fusion genes would be introduced.

Aptamer-targeted DNA nanostructures with doxorubicin to treat protein tyrosine kinase 7-positive tumours

Objectives

Aptamer sgc8c is a short DNA sequence that can target protein tyrosine kinase 7 (PTK7), which was overexpressed on many tumour cells. This study aimed to fabricate a novelty DNA nanostructure drug delivery system target on PTK7‐positive cells—CCRF‐CEM (human T‐cell ALL).

Methods

Aptamer‐modified tetrahedron DNA was synthesized through one‐step thermal annealing process. The sgc8c‐TDNs (s‐TDNs) loading DOX complexes were applied to investigate the effect to PTK7‐negative and ‐positive cells.

Results

When s‐TDN:DOX acted on PTK7‐positive and ‐negative cells respectively, the complexes exhibited specific toxic effect on PTK7‐positive cells but not on PTK7‐negative Ramos cells in vitro research.

Conclusions

In this work, we successfully constructed a PTK7‐targeting aptamer‐guided DNA tetrahedral nanostructure (s‐TDN) as a drug delivery system via a facile one‐pot synthesis method. The results showed that s‐TDN:DOX exhibited enhanced cytotoxicity against PTK7‐positive CCRF‐CEM cells, with a minor effect against PTK7‐negative Ramos cells. Hence, this functionalized TDNs drug delivery system displayed its potential application in targeting PTK7‐positive tumour T‐cell acute lymphoblastic leukaemia.

Combination of dihydromyricetin and ondansetron strengthens antiproliferative efficiency of adriamycin in K562/ADR through downregulation of SORCIN: A new strategy of inhibiting P-glycoprotein

Though the advancement of chemotherapy drugs alleviates the progress of cancer, long-term therapy with anticancer agents gradually leads to acquired multidrug resistance (MDR), which limits the survival outcomes in patients. It was shown that dihydromyricetin (DMY) could partly reverse MDR by suppressing P-glycoprotein (P-gp) and soluble resistance-related calcium-binding protein (SORCIN) independently. To reverse MDR more effectively, a new strategy was raised, that is, circumventing MDR by the coadministration of DMY and ondansetron (OND), a common antiemetic drug, during cancer chemotherapy. Meanwhile, the interior relation between P-gp and SORCIN was also revealed. The combination of DMY and OND strongly enhanced antiproliferative efficiency of adriamycin (ADR) because of the increasing accumulation of ADR in K562/ADR-resistant cell line. DMY could downregulate the expression of SORCIN and P-gp via the ERK/Akt pathways, whereas OND could not. In addition, it was proved that SORCIN suppressed ERK and Akt to inhibit P-gp by the silence of SORCIN, however, not vice versa. Finally, the combination of DMY, OND, and ADR led to G2/M cell cycle arrest and apoptosis via resuming P53 function and restraining relevant proteins expression. These fundamental findings provided a promising approach for further treatment of MDR.

Functionalized carbon nanotubes as emerging delivery system for the treatment of cancer

In recent time, carbon nanotubes (CNTs) have gained vital importance for pharmaceutical formulation scientist for delivering drugs and genes, owing to their excellent surface properties. For example, their aspect ratio is thought to be responsible for their excellent cell penetration aptitude; anisotropic conductivity/semi-conductivity along their axis is ideal for integration with nervous and muscular tissue; an ultrahigh surface area maximizes their ability to "talk" with biological matter; the hollow interior provides an enormous cargo-carrying capacity for drug delivery; and their exteriors are readily functionalized to permit tailoring of solubility and biological recognition. Despite their immense capabilities for the delivery of drugs, genes and other biomedically essential materials, there use is restricted primarily because of the severe toxicity. However, the reactive nature of the surface of the CNTs allowed attaching the guest molecules (drug, siRNA, and diagnostics) of interest which helps in increasing the biocompatibility of these novel nanocarriers. As per the need, CNTs can be modified with peptides, organic molecules, carbohydrates, polymers and used mainly for cancer targeting and tumor cell accumulation. This review expounds different functionalization strategies employed for CNTs that created new opportunities for scientists to improve the potential of delivered therapeutics.

Aptamer Therapeutics in Cancer: Current and Future

Aptamer-related technologies represent a revolutionary advancement in the capacity to rapidly develop new classes of targeting ligands. Structurally distinct RNA and DNA oligonucleotides, aptamers mimic small, protein-binding molecules and exhibit high binding affinity and selectivity. Although their molecular weight is relatively small—approximately one-tenth that of monoclonal antibodies—their complex tertiary folded structures create sufficient recognition surface area for tight interaction with target molecules. Additionally, unlike antibodies, aptamers can be readily chemically synthesized and modified. In addition, aptamers’ long storage period and low immunogenicity are favorable properties for clinical utility. Due to their flexibility of chemical modification, aptamers are conjugated to other chemical entities including chemotherapeutic agents, siRNA, nanoparticles, and solid phase surfaces for therapeutic and diagnostic applications. However, as relatively small sized oligonucleotides, aptamers present several challenges for successful clinical translation. Their short plasma half-lives due to nuclease degradation and rapid renal excretion necessitate further structural modification of aptamers for clinical application. Since the US Food and Drug Administration (FDA) approval of the first aptamer drug, Macugen^® (pegaptanib), which treats wet-age-related macular degeneration, several aptamer therapeutics for oncology have followed and shown promise in pre-clinical models as well as clinical trials. This review discusses the advantages and challenges of aptamers and introduces therapeutic aptamers under investigation and in clinical trials for cancer treatments.

Homogeneous electrochemical aptasensor based on a dual amplification strategy for sensitive detection of profenofos residues

A homogeneous type of electrochemical aptasensor was designed based upon the principle of target-induced and tool enzyme-assisted signal amplification, which was employed for the detection of profenofos residues.