Targeting EGFR/HER2/HER3 with a Three-in-One Aptamer-siRNA Chimera Confers Superior Activity against HER2+ Breast Cancer

Aptamer inhibits P-glycoprotein efflux function via the Wnt/β-catenin signaling pathway

Inhibiting permeability glycoprotein (P-gp) efflux is a strategy to enhance drug efficacy or overcome multidrug resistance in tumors. However, whether P-gp aptamer (APTP-gp, an 81 bp ssDNA) inhibits P-gp efflux is unknown. Increased Rho123 uptake was observed in the rat brain and intestine. Bidirectional transport of Rho123 indicated that 100 nM of APTP-gp inhibited P-gp activity with inhibition ratios of 75.0 % in Caco-2 and 60.5 % in hCMEC/D3 cells. The apparent permeability coefficients (Papp) from the apical (AP) to basolateral (BL) sides significantly increased by 129.4 % in Caco-2 and 8.0 % in hCMEC/D3 cells, respectively. The Papp from the BL→AP sides in the two cell lines decreased. P-gp mRNA and protein expression in the rat ileum, brain, and two cell lines markedly decreased following APTP-gp exposure. APTP-gp downregulated Wnt3, pho-Dvl2, β-catenin expression and decreased the ratio of pho-GSK-3β to GSK-3β in the rat ileum and brain. Molecular docking analysis suggested that APTP-gp interact with Wnt/β-catenin signaling pathway proteins at various amino acid sites. The present study reports a novel a novel nucleic acid-based P-gp inhibitor, which may benefit for enhancing drug efficacy or overcome multidrug resistance in clinical application.

Multifunctional molecular hybrid for targeted colorectal cancer cells: Integrating doxorubicin, AS1411 aptamer, and T9/U4 ASO

Colorectal cancer (CRC) poses a global health challenge, with current treatments often harming both cancerous and normal cells. To improve efficacy, a multifunctional drug delivery platform has been developed, integrating bioactive materials, anticancer agents, and targeted recognition ligands into a single molecule. This study aimed to create a molecular hybrid (MH) containing doxorubicin, AS1411 aptamer, and T9/U4 ASO to regulate SW480 cell proliferation. The AS1411 aptamer targets nucleolin, overexpressed on cancer cell membranes, while T9/U4 ASO inhibits human telomerase RNA activity, further hindering cancer cell proliferation. AS-T9/U4_MH was synthesized via oligonucleotide hybridization, followed by doxorubicin loading and evaluation of its impact on cell proliferation. Binding capability of this MH was verified using fluorescence microscopy and flow cytometry, demonstrating specific recognition of SW480 cells due to nucleolin availability on the cell surface. These findings were corroborated by both microscopy and flow cytometry. AS-T9/U4_MH exhibited anti-proliferative effects, with the doxorubicin-loaded system demonstrating encapsulation and reduced toxicity. Moreover, the presence of Dox within AS-T9/U4_MH led to a notable reduction in hTERT and vimentin expression in SW480 cells. Additionally, examination of apoptotic pathways unveiled a marked decrease in Bcl-2 expression and a simultaneous increase in Bax expression in SW480 cells treated with Dox-loaded AS-T9/U4_MH, indicating its impact on promoting apoptosis. This molecular hybrid shows promise as a platform for integrating chemotherapeutic drugs with bioactive materials for cancer therapy.

Targeted Delivery of AR-V7 siRNA with Bivalent PSMA Aptamers Effectively Suppresses the Growth of Enzalutamide-Resistant Prostate Cancer

Androgen deprivation therapy has been the primary treatment strategy for advanced prostate cancer (PCa). But most patients develop castration resistance over time. For FDA-approved second-generation androgen receptor (AR) antagonists, including enzalutamide (ENZ) and abiraterone (AA), patients who initially respond to them eventually develop resistance. The key mechanism for resistance to ENZ/AA involves AR splice variants (AR-Vs) and specifically AR-V7. Current AR antagonists cannot target AR-V7 due to its lack of the C-terminal ligand-binding domain (LBD) but keeping the AR N-terminal domain (NTD) which still can activate androgen-responsive genes. Therefore, targeting the AR NTD and AR-V7 is critically important to overcome ENZ resistance. Unfortunately, AR NTD has been considered an "undruggable" target due to the difficulty in defining its three-dimensional (3D) structure. In this context, siRNA is highly suitable to address this undruggable target. However, siRNA cannot freely diffuse into cells, and a carrier is needed. In this regard, nucleic acid-based aptamers are highly suitable for cell type-specific delivery of siRNA in vivo. In this study, we have developed a serum-stable bivalent prostate-specific membrane antigen (PSMA) aptamer-AR-V7 siRNA chimera (PAP). The results show that PAP can knock down both AR-full length and AR-V7 in PSMA-expressing castration-resistant cells. It can resensitize ENZ in cell lines and PCa xenografts. ENZ combined with PAP can significantly inhibit 22Rv1 xenograft growth in mice without experiencing castration. Owing to the low toxicity, PAP has potential to offer a new antiandrogen treatment for current ENZ-resistant PCa.

Recent advancements in small interfering RNA based therapeutic approach on breast cancer

Breast cancer (BC) is the most common and malignant tumor diagnosed in women, with 2.9 million cases in 2023 and the fifth highest cancer-causing mortality worldwide. Recent developments in targeted therapy options for BC have demonstrated the promising potential of small interfering RNA (siRNA)-based cancer therapeutic approaches. As BC continues to be a global burden, siRNA therapy emerges as a potential treatment strategy to regulate disease-related genes in other types of cancers, including BC. siRNAs are tiny RNA molecules that, by preventing their expression, can specifically silence genes linked to the development of cancer. In order to increase the stability and effectiveness of siRNA delivery to BC cells, minimize off-target effects, and improve treatment efficacy, advanced delivery technologies such as lipid nanoparticles and nanocarriers have been created. Additionally, combination therapies, such as siRNAs that target multiple pathways are used in conjunction with conventional chemotherapy agents, have shown synergistic effects in various preclinical studies, opening up new treatment options for breast cancer that are personalized and precision medicine-oriented. Targeting important genes linked to BC growth, metastasis, and chemo-resistance has been reported in BC research using siRNA-based therapies. This study reviews recent reports on therapeutic approaches to siRNA for advanced treatment of BC. Furthermore, this review evaluates the role and mechanisms of siRNA in BC and demonstrates the potential of exploiting siRNA as a novel target for BC therapy.

Plug-and-play nucleic acid-mediated multimerization of biparatopic nanobodies for molecular imaging

In cancer molecular imaging, selecting binders with high specificity and affinity for biomarkers is paramount for achieving high-contrast imaging within clinical time frames. Nanobodies have emerged as potent candidates, surpassing antibodies in pre-clinical imaging due to their convenient production, rapid renal clearance, and deeper tissue penetration. Multimerization of nanobodies is a popular strategy to enhance their affinity and pharmacokinetics; however, traditional methods are laborious and may yield heterogeneous products. In this study, we employ a Holliday junction (HJ)-like nucleic acid-based scaffold to create homogeneous nanostructures with precise multivalent and multiparatopic nanobody displays. The plug-and-play assembly allowed the screening of several nanobody multimer configurations for the detection of the breast cancer biomarker, human epidermal growth factor receptor 2 (HER2). In vitro studies demonstrated significant improvements in binding avidity, particularly with the biparatopic construct exhibiting high sensitivity, surpassing that of traditional antibody-based cell binding. Furthermore, our HJ platform allowed for adaptation from fluorescence-based to nuclear imaging, as demonstrated in xenografted mice, thereby allowing for future in vivo applications. This work highlights the potential of nucleic acid-mediated multimerization to markedly enhance nanobody binding, by exploring synergistic combinations and offering versatility for both in vitro diagnostics and cancer molecular imaging with prospects for future theranostic applications.

Peptide-drug conjugate designated for targeted delivery to HER2-expressing cancer cells

Targeted therapy of the highest globally incident breast cancer shall resolve the issue of off-target toxicity concurring with augmented killing of specific diseased cells. Thus, the goal of this study was to prepare a peptide-drug conjugate targeting elevated expression of HER2 receptors in breast cancer. Towards this, the rL-A9 peptide was conjugated with the chemotherapeutic drug doxorubicin (DOX) through a N-succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC) linker. The synthesized peptide-drug conjugate, rL-A9-DOX, was characterized by mass spectrometry. Molecular docking studies, based on binding energy data, suggested a stronger interaction of rL-A9-DOX with the HER2 receptor in comparison to the unconjugated peptide, rL-A9. The cytotoxic effect of the rL-A9-DOX conjugate was observed to be higher in HER2-positive SKOV3 cells compared to HER2-negative MDA-MB-231 cells, indicating selective cell killing. Cellular internalization of the rL-A9-DOX conjugate was evident from the flow cytometry analysis, where a noticeable shift in mean fluorescent intensity (MFI) was observed for the conjugate compared to the control group. This data was further validated by confocal microscopy, where the fluorescent signal ascertained nuclear accumulation of rL-A9-DOX. The present studies highlight the promising potential of rL-A9-DOX for targeted delivery of the drug into a defined group of cancer cells.

Investigating the Co-Expression Rate of HER2 and HER3 Biomarkers in Cancer Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Many types of cancer express the HER2/HER3 heterodimer, which is a crucial oncogenic unit. Research has shown that when these two biomarkers are expressed together, it correlates with higher tumor aggressiveness and lower overall survival rate. Therefore, many therapies have been developed to target both biomarkers simultaneously. This study aims to collect data on the co-expression levels of these biomarkers across different types of cancers.

METHODS

A comprehensive search was conducted across PubMed, Scopus, Embase, and Web of Science databases to identify relevant studies. The event rates and their corresponding 95% confidence intervals were calculated. Heterogeneity, subgroup, and meta-regression analyses were conducted based on patients' residency region, age, and gender. The protocol of this study was registered in PROSPERO under ID: CRD42024504256.

RESULTS

We have detected 60 studies that met all of the inclusion criteria for our research. Out of these, we have focused on a total of 19 studies (with 6,079 participants) related to breast cancer, 9 studies (with 829 participants) related to lung cancer, 6 studies (with 1423 participants) related to gastric cancer, and 4 studies (with 802 participants) related to colorectal cancer for conducting our meta-analysis. According to our results, the co-expression rate of HER2 and HER3 in breast cancer patients is 18.5% (95%CI 11.7-27.9), in colorectal cancer patients is 17.1% (95%CI 2.4-63.4), in gastric cancer patients is 11.3% (95%CI 4.2-17.2), and in lung cancer patients is 12.7% (95%CI 5.2-22.8). The co-expression of HER2 and HER3 in lung cancer has a significant association with patients' gender (P=0.038).

CONCLUSION

The study found that HER2 and HER3 biomarkers, which are targets for different therapies, are co-expressed in various types of cancer.

HER3 receptor and its role in the therapeutic management of metastatic breast cancer

Metastatic breast cancer (mBC) poses a significant threat to women's health and is a major cause of malignant neoplasms in women. Human epidermal growth factor receptor (HER)3, an integral member of the ErbB/HER receptor tyrosine kinase family, is a crucial activator of the phosphoinositide-3 kinase/protein kinase B signaling pathway. HER3 overexpression significantly contributes to the development of resistance to drugs targeting other HER receptors, such as HER2 and epidermal growth factor receptors, and plays a crucial role in the onset and progression of mBC. Recently, numerous HER3-targeted therapeutic agents, such as monoclonal antibodies (mAbs), bispecific antibodies (bAbs), and antibody-drug conjugates (ADCs), have emerged. However, the efficacy of HER3-targeted mAbs and bAbs is limited when used individually, and their combination may result in toxic adverse effects. On the other hand, ADCs are cytotoxic to cancer cells and can bind to target cells through antibodies, which highlights their use in targeted HER3 therapy for mBC. This review provides an overview of recent advancements in HER3 research, historical initiatives, and innovative approaches in targeted HER3 therapy for metastatic breast cancer. Evaluating the advantages and disadvantages of current methods may yield valuable insights and lessons.

Combined SERS-Raman screening of HER2-overexpressing or silenced breast cancer cell lines

BACKGROUND

Breast cancer (BC) is a heterogeneous neoplasm characterized by several subtypes. One of the most aggressive with high metastasis rates presents overexpression of the human epidermal growth factor receptor 2 (HER2). A quantitative evaluation of HER2 levels is essential for a correct diagnosis, selection of the most appropriate therapeutic strategy and monitoring the response to therapy.

RESULTS

In this paper, we propose the synergistic use of SERS and Raman technologies for the identification of HER2 expressing cells and its accurate assessment. To this end, we selected SKBR3 and MDA-MB-468 breast cancer cell lines, which have the highest and lowest HER2 expression, respectively, and MCF10A, a non-tumorigenic cell line from normal breast epithelium for comparison. The combined approach provides a quantitative estimate of HER2 expression and visualization of its distribution on the membrane at single cell level, clearly identifying cancer cells. Moreover, it provides a more comprehensive picture of the investigated cells disclosing a metabolic signature represented by an elevated content of proteins and aromatic amino acids. We further support these data by silencing the HER2 gene in SKBR3 cells, using the RNA interference technology, generating stable clones further analysed with the same combined methodology. Significant changes in HER2 expression are detected at single cell level before and after HER2 silencing and the HER2 status correlates with variations of fatty acids and downstream signalling molecule contents in the context of the general metabolic rewiring occurring in cancer cells. Specifically, HER2 silencing does reduce the growth ability but not the lipid metabolism that, instead, increases, suggesting that higher fatty acids biosynthesis and metabolism can occur independently of the proliferating potential tied to HER2 overexpression.

CONCLUSIONS

Our results clearly demonstrate the efficacy of the combined SERS and Raman approach to definitely pose a correct diagnosis, further supported by the data obtained by the HER2 gene silencing. Furthermore, they pave the way to a new approach to monitor the efficacy of pharmacologic treatments with the aim to tailor personalized therapies and optimize patients' outcome.

HER2 siRNA Facilitated Gene Silencing Coupled with Doxorubicin Delivery: A Dual Responsive Nanoplatform Abrogates Breast Cancer

The present study investigated the concurrent delivery of antineoplastic drug, doxorubicin, and HER2 siRNA through a targeted theranostic metallic gold nanoparticle designed using polysaccharide, PSP001. The as-synthesized HsiRNA@PGD NPs were characterized in terms of structural, functional, physicochemical, and biological properties. HsiRNA@PGD NPs exposed adequate hydrodynamic size, considerable ζ potential, and excellent drug/siRNA loading and encapsulation efficiency. Meticulous exploration of the biocompatible dual-targeted nanoconjugate exhibited an appealing biocompatibility and pH-sensitive cargo release kinetics, indicating its safety for use in clinics. HsiRNA@PGD NPs deciphered competent cancer cell internalization, enhanced cytotoxicity mediated via the induction of apoptosis, and excellent downregulation of the overexpressing target HER2 gene. Further in vivo explorations in the SKBR3 xenograft breast tumor model revealed the appealing tumor reduction properties, selective accumulation in the tumor site followed by significant suppression of the HER2 gene which contributed to the exclusive abrogation of breast tumor mass by the HsiRNA@PGD NPs. Compared to free drugs or the monotherapy constructs, the dual delivery approach produced a synergistic suppression of breast tumors both in vitro and in vivo. Hence the drawings from these findings implicate that the as-synthesized HsiRNA@PGD NPs could offer a promising platform for chemo-RNAi combinational breast cancer therapy.

Structural DNA nanotechnology at the nexus of next-generation bio-applications: challenges and perspectives

DNA nanotechnology has significantly progressed in the last four decades, creating nucleic acid structures widely used in various biological applications. The structural flexibility, programmability, and multiform customization of DNA-based nanostructures make them ideal for creating structures of all sizes and shapes and multivalent drug delivery systems. Since then, DNA nanotechnology has advanced significantly, and numerous DNA nanostructures have been used in biology and other scientific disciplines. Despite the progress made in DNA nanotechnology, challenges still need to be addressed before DNA nanostructures can be widely used in biological interfaces. We can open the door for upcoming uses of DNA nanoparticles by tackling these issues and looking into new avenues. The historical development of various DNA nanomaterials has been thoroughly examined in this review, along with the underlying theoretical underpinnings, a summary of their applications in various fields, and an examination of the current roadblocks and potential future directions.

RNA nanostructures for targeted drug delivery and imaging

The RNA molecule plays a pivotal role in many biological processes by relaying genetic information, regulating gene expression, and serving as molecular machines and catalyzers. This inherent versatility of RNA has fueled significant advancements in the field of RNA nanotechnology, driving the engineering of complex nanoscale architectures toward biomedical applications, including targeted drug delivery and bioimaging. RNA polymers, serving as building blocks, offer programmability and predictability of Watson-Crick base pairing, as well as non-canonical base pairing, for the construction of nanostructures with high precision and stoichiometry. Leveraging the ease of chemical modifications to protect the RNA from degradation, researchers have developed highly functional and biocompatible RNA architectures and integrated them into preclinical studies for the delivery of payloads and imaging agents. This review offers an educational introduction to the use of RNA as a biopolymer in the design of multifunctional nanostructures applied to targeted delivery in vivo, summarizing physical and biological barriers along with strategies to overcome them. Furthermore, we highlight the most recent progress in the development of both small and larger RNA nanostructures, with a particular focus on imaging reagents and targeted cancer therapeutics in pre-clinical models and provide insights into the prospects of this rapidly evolving field.

Inhibiting HER3 Hyperphosphorylation in HER2-Overexpressing Breast Cancer through Multimodal Therapy with Branched Gold Nanoshells

Treatment failure in breast cancers overexpressing human epidermal growth factor receptor 2 (HER2) is associated mainly to the upregulation of human epidermal growth factor receptor 3 (HER3) oncoprotein linked to chemoresitence. Therefore, to increase patient survival, here a multimodal theranostic nanoplatform targeting both HER2 and HER3 is developed. This consists of doxorubicin-loaded branched gold nanoshells functionalized with the near-infrared (NIR) fluorescent dye indocyanine green, a small interfering RNA (siRNA) against HER3, and the HER2-specific antibody Transtuzumab, able to provide a combined therapeutic outcome (chemo- and photothermal activities, RNA silencing, and immune response). In vitro assays in HER2+ /HER3+ SKBR-3 breast cancer cells have shown an effective silencing of HER3 by the released siRNA and an inhibition of HER2 oncoproteins provided by Trastuzumab, along with a decrease of the serine/threonine protein kinase Akt (p-AKT) typically associated with cell survival and proliferation, which helps to overcome doxorubicin chemoresistance. Conversely, adding the NIR light therapy, an increment in p-AKT concentration is observed, although HER2/HER3 inhibitions are maintained for 72 h. Finally, in vivo studies in a tumor-bearing mice model display a significant progressively decrease of the tumor volume after nanoparticle administration and subsequent NIR light irradiation, confirming the potential efficacy of the hybrid nanocarrier.

Engineering siRNA therapeutics: challenges and strategies

Small interfering RNA (siRNA) is a potential method of gene silencing to target specific genes. Although the U.S. Food and Drug Administration (FDA) has approved multiple siRNA-based therapeutics, many biological barriers limit their use for treating diseases. Such limitations include challenges concerning systemic or local administration, short half-life, rapid clearance rates, nonspecific binding, cell membrane penetration inability, ineffective endosomal escape, pH sensitivity, endonuclease degradation, immunological responses, and intracellular trafficking. To overcome these barriers, various strategies have been developed to stabilize siRNA, ensuring their delivery to the target site. Chemical modifications implemented with nucleotides or the phosphate backbone can reduce off-target binding and immune stimulation. Encapsulation or formulation can protect siRNA from endonuclease degradation and enhance cellular uptake while promoting endosomal escape. Additionally, various techniques such as viral vectors, aptamers, cell-penetrating peptides, liposomes, and polymers have been developed for delivering siRNA, greatly improving their bioavailability and therapeutic potential.

Aptamers against cancer drug resistance: Small fighters switching tactics in the face of defeat

Discovering novel cancer therapies has attracted extreme interest in the last decade. In this regard, multidrug resistance (MDR) to chemotherapies is a key challenge in cancer treatment. Cancerous cells are growingly become resistant to existing chemotherapeutics by employing diverse mechanisms, highlighting the significance of discovering approaches to overcome MDR. One promising strategy is utilizing aptamers as unique tools to target elements or signaling pathways incorporated in resistance mechanisms, or develop actively targeted drug delivery systems or chimeras enabling the precise delivery of novel agents to inhibit the conventionally undruggable resistance elements. Furthermore, due to their advantages over their proteinaceous counterparts, particularly antibodies, including improved targeting action, enhanced thermal stability, easier production, and superior tumor penetration, aptamers are emerging and have frequently been considered for developing cancer therapeutics. Here, we highlighted significant chemoresistance pathways in cancer and discussed the use of aptamers as prospective tools to surmount cancer MDR.

Tools and techniques for the discovery of therapeutic aptamers: recent advances

INTRODUCTION

The pursuit of novel therapeutic agents for serious diseases such as cancer has been a global endeavor. Aptamers characteristic of high affinity, programmability, low immunogenicity, and rapid permeability hold great promise for the treatment of diseases. Yet obtaining the approval for therapeutic aptamers remains challenging. Consequently, researchers are increasingly devoted to exploring innovative strategies and technologies to advance the development of these therapeutic aptamers.

AREAS COVERED

The authors provide a comprehensive summary of the recent progress of the SELEX (Systematic Evolution of Ligands by EXponential enrichment) technique, and how the integration of modern tools has facilitated the identification of therapeutic aptamers. Additionally, the engineering of aptamers to enhance their functional attributes, such as inhibiting and targeting, is discussed, demonstrating the potential to broaden their scope of utility.

EXPERT OPINION

The grand potential of aptamers and the insufficient development of relevant drugs have spurred countless efforts for stimulating their discovery and application in the therapeutic field. While SELEX techniques have undergone significant developments with the aid of advanced analysis instruments and ingeniously updated aptameric engineering strategies, several challenges still impede their clinical translation. A key challenge lies in the insufficient understanding of binding conformation and susceptibility to degradation under physiological conditions. Despite the hurdles, our opinion is optimistic. With continued progress in overcoming these obstacles, the widespread utilization of aptamers for clinical therapy is envisioned to become a reality soon.

Diosgenin and Monohydroxy Spirostanol from Prunus amygdalus var amara Seeds as Potential Suppressors of EGFR and HER2 Tyrosine Kinases: A Computational Approach

Cancer continues to be leading cause of death globally, with nearly 7 million deaths per year. Despite significant progress in cancer research and treatment, there remain several challenges to overcome, including drug resistance, the presence of cancer stem cells, and high interstitial fluid pressure in tumors. To tackle these challenges, targeted therapy, specifically targeting HER2 (Human Epidermal Growth Factor Receptor 2) as well as EGFR (Epidermal Growth Factor Receptor), is considered a promising approach in cancer treatment. In recent years, phytocompounds have gained recognition as a potential source of chemopreventive and chemotherapeutic agents in tumor cancer treatment. Phytocompounds are compounds derived from medicinal plants that have the potential to treat and prevent cancer. This study aimed to investigate phytocompounds from Prunus amygdalus var amara seeds as inhibitors against EGFR and HER2 enzymes using in silico methods. In this study, fourteen phytocompounds were isolated from Prunus amygdalus var amara seeds and subjected to molecular docking studies to determine their ability to bind to EGFR and HER2 enzymes. The results showed that diosgenin and monohydroxy spirostanol exhibited binding energies comparable to those of the reference drugs, tak-285, and lapatinib. Furthermore, the drug-likeness and ADMET predictions, performed using the admetSAR 2.0 web-server tool, suggested that diosgenin and monohydroxy spirostanol have similar safety and ADMET properties as the reference drugs. To get deeper insight into the structural steadiness and flexibility of the complexes formed between these compounds and theEGFR and HER2 proteins, molecular dynamics simulations were performed for 100 ns. The results showed that the hit phytocompounds did not significantly affect the stability of the EGFR and HER2 proteins and were able to form stable interactions with the catalytic binding sites of the proteins. Additionally, the MM-PBSA analysis revealed that the binding free energy estimates for diosgenin and monohydroxy spirostanol is comparable to the reference drug, lapatinib. This study provides evidence that diosgenin and monohydroxy spirostanol may have the potential to act as dual suppressors of EGFR and HER2. Additional in vivo and in vitro research are needed to certify these results and assess their efficacy and safety as cancer therapy agents. The experimental data reported and these results are in agreement.

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.

siRNA and targeted delivery systems in breast cancer therapy

Recently, nucleic acid drugs have been considered as promising candidates in treatment of various diseases, especially cancer. Because of developing resistance to conventional chemotherapy, use of genetic tools in cancer therapy appears inevitable. siRNA is a RNAi tool with capacity of suppressing target gene. Owing to overexpression of oncogenic factors in cancer, siRNA can be used for suppressing those pathways. This review emphasizes the function of siRNA in treatment of breast tumor. The anti-apoptotic-related genes including Bcl-2, Bcl-xL and survivin can be down-regulated by siRNA in triggering cell death in breast cancer. STAT3, STAT8, Notch1, E2F3 and NF-κB are among the factors with overexpression in breast cancer that their silencing by siRNA paves the way for impairing tumor proliferation and invasion. The oncogenic mechanisms in drug resistance development in breast tumor such as lncRNAs can be suppressed by siRNA. Furthermore, siRNA reducing P-gp activity can increase drug internalization in tumor cells. Because of siRNA degradation at bloodstream and low accumulation at tumor site, nanoplatforms have been employed for siRNA delivery to suppress breast tumor progression via improving siRNA efficacy in gene silencing. Development of biocompatible and efficient nanostructures for siRNA delivery can make milestone progress in alleviation of breast cancer patients.

siAKR1C3@PPA complex nucleic acid nanoparticles inhibit castration-resistant prostate cancer in vitro

Introduction

AKR1C3, as a crucial androgenic enzyme, implicates the androgen biosynthesis and promoting prostate cancer cell growth in vitro. This study provides a new gene therapy strategy for targeting AKR1C3 to treat castration-resistant prostate cancer.

Methods

siAKR1C3@PPA is assembled from PEG3500, PAMAM, Aptamer-PSMA, and siRNA for AKR1C3. We analyzed the relationship between AKR1C3 expression and the survival rate of prostate cancer patients based on the GEPIA online database to perform disease-free survival, and found that AKR1C3 may be an important factor leading to poor prognosis in prostate cancer. Considering AKR1C3 as a therapeutic target for castration-resistant prostate cancer, we constructed a complex nucleic acid nanoparticle, siAKR1C3@PPA to investigate the inhibitory effect on castration-resistant prostate cancer.

Results

Aptamer-PSMA acts as a target to guide siAKR1C3@PPA into PSMA-positive prostate cancer cells and specifically down regulate AKR1C3. Cyclin D1 was decreased as a result of siAKR1C3@PPA treatment. Changes in Cyclin D1 were consistent with decreased expression of AKR1C3 in LNCaP-AKR1C3 cells and 22RV1 cells. Furthermore, in the LNCaP-AKR1C3 group, 1070 proteins were upregulated and 1015 proteins were downregulated compared to the LNCaP group according to quantitative 4D label-free proteomics. We found 42 proteins involved in cell cycle regulation. In a validated experiment, we demonstrated that PCNP and CINP were up-regulated, and TERF2 and TP53 were down-regulated by western blotting.

Conclusion

We concluded that siAKR1C3@PPA may arrest the cell cycle and affect cell proliferation.

The race to develop oral SERDs and other novel estrogen receptor inhibitors: recent clinical trial results and impact on treatment options

Hormonal therapy plays a vital part in the treatment of estrogen receptor-positive (ER +) breast cancer. ER can be activated in a ligand-dependent and independent manner. Currently available ER-targeting agents include selective estrogen receptor modulators (SERMs), selective estrogen receptor degraders (SERDs), and aromatase inhibitors (AIs). Estrogen receptor mutation (ESR1 mutation) is one of the common mechanisms by which breast cancer becomes resistant to additional therapies from SERMs or AIs. These tumors remain sensitive to SERDs such as fulvestrant. Fulvestrant is limited in clinical utilization by its intramuscular formulation and once-monthly injection in large volumes. Oral SERDs are being rapidly developed to replace fulvestrant with the potential of higher efficacy and lower toxicities. Elacestrant is the first oral SERD that went through a randomized phase III trial showing increased efficacy, especially in tumors bearing ESR1 mutation, and good tolerability. Two other oral SERDs recently failed to achieve the primary endpoints of longer progression-free survival (PFS). They targeted tumors previously treated with several lines of prior therapies untested for ESR1 mutation. Initial clinical trial data demonstrated that tumors without the ESR1 mutation are less likely to benefit from the SERDs and may still respond to SERMs or AIs, including tumors previously exposed to hormonal therapy. Testing for ESR1 mutation in ongoing clinical trials and in hormonal therapy for breast cancer is highly recommended. Novel protein degradation technologies such as proteolysis-targeting chimera (PROTACS), molecular glue degrader (MGD), and lysosome-targeting chimeras (LYTACS) may result in more efficient ER degradation, while ribonuclease-targeting chimeras (RIBOTAC) and small interfering RNA (siRNA) may inhibit the production of ER protein.

HER3 in cancer: from the bench to the bedside

The HER3 protein, that belongs to the ErbB/HER receptor tyrosine kinase (RTK) family, is expressed in several types of tumors. That fact, together with the role of HER3 in promoting cell proliferation, implicate that targeting HER3 may have therapeutic relevance. Furthermore, expression and activation of HER3 has been linked to resistance to drugs that target other HER receptors such as agents that act on EGFR or HER2. In addition, HER3 has been associated to resistance to some chemotherapeutic drugs. Because of those circumstances, efforts to develop and test agents targeting HER3 have been carried out. Two types of agents targeting HER3 have been developed. The most abundant are antibodies or engineered antibody derivatives that specifically recognize the extracellular region of HER3. In addition, the use of aptamers specifically interacting with HER3, vaccines or HER3-targeting siRNAs have also been developed. Here we discuss the state of the art of the preclinical and clinical development of drugs aimed at targeting HER3 with therapeutic purposes.

Aptamer-siRNA chimeras: Promising tools for targeting HER2 signaling in cancer

RNA interference is a transformative approach and has great potential in the development of novel and more efficient cancer therapeutics. Immense prospects exist in the silencing of HER2 and its downstream genes which are overexpressed in many cancers, through exogenously delivered siRNA. However, there is still a long way to exploit the full potential and versatility of siRNA therapeutics due to the challenges associated with the stability and delivery of siRNA targeted to specific sites. Aptamers offer several advantages as a vehicle for siRNA delivery, over other carriers such as antibodies. In this review, we discuss the progress made in the development and applications of aptamer-siRNA chimeras in HER2 targeting and gene silencing. A schematic workflow is also provided which will provide ample insight for all those researchers who are new to this field. Also, we think that a mechanistic understanding of the HER2 signaling pathway is crucial in designing extensive investigations aimed at the silencing of a wider array of genes. This review is expected to stimulate more research on aptamer-siRNA chimeras targeted against HER2 which might arm us with potential effective therapeutic interventions for the management of cancer.

Acid-Directed Electrostatic Self-Assembly Generates Charge-Reversible Bacteria for Enhanced Tumor Targeting and Low Tissue Trapping

Despite recent preclinical progress with oncolytic bacteria in cancer therapy, dose-limiting toxicity has been a long-standing challenge for clinical application. Genetic and chemical modifications for enhancing the bacterial tumor-targeting ability have been unable to establish a balance between increasing its specificity and effectiveness while decreasing side effects. Herein, we report a simple, highly efficient method for rapidly self-assembling a clinically used lipid on bacterium and for reducing its minimum effective dose and toxicity to normal organs. The resultant bacteria present the ability to reverse-charge between neutral and acidic solutions, thus enabling weak interactions with the negatively charged normal cells, hence increasing their biocompatibility with blood cells and with the immune system. Additionally, the lipid-coated bacteria exhibit a longer blood circulation lifetime and low tissue trapping compared with the wild-type strains. Thereby, the engineered bacteria show enhanced tumor specificity and effectiveness even at low doses. Multiple visualization techniques are used for vividly demonstrating the time course of bacterial circulation in the blood and normal organs after intravenous administration. We believe that these methods for biointerfacial lipid self-assembly and evaluation of bacterial systemic circulation possess vast potential in exquisitely fabricating engineered bacteria for cancer therapy in the future.

Triple Targeting of HER Receptors Overcomes Heregulin-mediated Resistance to EGFR Blockade in Colorectal Cancer

Current treatment options for patients with advanced colorectal cancers include anti-EGFR/HER1 therapy with the blocking antibody cetuximab. Although a subset of patients with KRAS WT disease initially respond to the treatment, resistance develops in almost all cases. Relapse has been associated with the production of the ligand heregulin (HRG) and/or compensatory signaling involving the receptor tyrosine kinases HER2 and HER3. Here, we provide evidence that triple-HER receptor blockade based on a newly developed bispecific EGFR×HER3-targeting antibody (scDb-Fc) together with the HER2-blocking antibody trastuzumab effectively inhibited HRG-induced HER receptor phosphorylation, downstream signaling, proliferation, and stem cell expansion of DiFi and LIM1215 colorectal cancer cells. Comparative analyses revealed that the biological activity of scDb-Fc plus trastuzumab was sometimes even superior to that of the combination of the parental antibodies, with PI3K/Akt pathway inhibition correlating with improved therapeutic response and apoptosis induction as seen by single-cell analysis. Importantly, growth suppression by triple-HER targeting was recapitulated in primary KRAS WT patient-derived organoid cultures exposed to HRG. Collectively, our results provide strong support for a pan-HER receptor blocking approach to combat anti-EGFR therapy resistance of KRAS WT colorectal cancer tumors mediated by the upregulation of HRG and/or HER2/HER3 signaling.

Trimethyl-Chitosan Coated Gold Nanoparticles Enhance Delivery, Cellular Uptake and Gene Silencing Effect of EGFR-siRNA in Breast Cancer Cells

Purpose: Despite the promising therapeutic effects of gene silencing with small interfering RNAs (siRNAs), the challenges associated with delivery of siRNAs to the tumor cells in vivo, has greatly limited its clinical application. To overcome these challenges, we employed gold nanoparticles modified with trimethyl chitosan (TMC) as an effective delivery carrier to improve the stability and cellular uptake of siRNAs against epidermal growth factor receptor (EGFR) that is implicated in breast cancer. Methods: AuNPs were prepared by the simple aqueous reduction of chloroauric acid (HAuCl4) with ascorbic acid and coated with synthesized TMC. EGFR-siRNA was then complexed with the AuNPs-TMC via electrostatic interaction to make AuNPs-TMC/EGFR-siRNA with a w/w ratio of 10:1. Nanoparticles were assessed for physicochemical characteristics and in vitro cellular behavior on MCF-7 breast cancer cell line. Results: Spherical and positively charged AuNPs-TMC (67 nm, +45 mV) were successfully complexed with EGFR-siRNA (82 nm, +11 mV) which were able to retard the gene migration completely. Confocal microscopy and flow cytometry analysis demonstrated complete cellular uptake of Cy5 labeled AuNPs-TMC in the MCF-7 cells after 4 h incubation. MTT test after 48 h incubation showed that the AuNPs-TMC were safe but when combined with EGFR-siRNA exert significant cytotoxicity while the cell viability was about 50%. These nanocomplexes also showed a high gene expression knockdown (86%) of EGFR and also a high apoptosis rate (Q2 + Q3 = 18.5%) after 24 h incubation. Conclusion: This study suggests that the simply synthesized AuNPs-TMC are novel, effective, and promising nanocarriers for siRNA delivery, and AuNPs-TMC/EGFR-siRNA appears to be a potential therapeutic agent for breast cancer treatment.

Recent advances in nanoscale targeted therapy of HER2-positive breast cancer

Breast cancer is the second leading cause of death among women with high mortality rates worldwide. The exceptionally fast rate of metastasis, the emergence of drug-resistant mechanisms, and the occurrence of inadvertent side effects by cytotoxic chemotherapies often make conventional chemotherapy and immunotherapy treatments ineffective. Similar to other solid tumors, breast cancer can develop unique cellular and molecular characteristics forming an atypical permissive tumor microenvironment (TME). Due to the unique features of TME, cancer cells can further proliferate and coadapt with the stromal cells and evade immunosurveillance. aberrantly abundantly express various pieces of molecular machinery (the so-called oncomarkers) in favor of their survival, progression, metastasis, and further invasion. Such overexpressed oncomarkers can be exploited in the targeted therapy of cancer. Among breast cancer oncomarkers, epidermal growth factor receptors, particularly HER2, are considered as clinically valid molecular targets not only for the thorough diagnosis but also for the targeted therapy of the disease using different conventional and advanced nanoscale treatment modalities. This review aims to elaborate on the recent advances in the targeted therapy of HER2-positive breast cancer, and discuss various types of multifunctional nanomedicines/theranostics, and antibody-/aptamer-drug conjugates.

Dual-Targeted Self-Assembled DNA Hydrogels Decorated With Multivalent Aptamers Loaded With DOX for Anticancer Therapy

Chemotherapy, as one of the principal modalities for cancer therapy, is limited by its non-specific and inefficient delivery to tumors. To overcome these limitations, we report herein a dual-targeted aptamer-decorated DNA hydrogel system (DTA-H) to achieve efficient, stable, and targeted delivery of drugs. Firstly, DNA hydrogel was formed by the rolling circle amplification. By reasonable design, double target and multivalent aptamers were decorated on DNA hydrogel to load DOX. The results confirmed that DTA-H can deliver chemotherapy drugs and aptamer nucleic acids drugs to target cells, inducing degradation of HER2 protein while chemotherapy is synergistic to inhibit HER2-positive breast cancer growth. The proposed drug delivery system has significant potential to achieve efficient, stable, and targeted delivery of drugs and cancer therapy.

Anti-HER2 therapy in metastatic breast cancer: many choices and future directions

Metastatic HER2 + breast cancer is an expanding area of drug development and research, with three new drugs approved in 2020 alone. While first-line therapy is well-established for metastatic HER2 + breast cancer, the standard of care for second-line therapy will likely be changing soon based on the results of the DESTINY-Breast03 trial. In the third-line setting, many options are available. Considerations in choosing between regimens in the third-line include resistance to trastuzumab, the presence of brain metastases, and tolerability. High rates of resistance exist in this setting particularly due to expression of p95, a truncated form of HER2 that constitutively activates downstream signaling pathways. We suggest a tyrosine kinase inhibitor (TKI)-based regimen because of the activity of TKIs in brain metastases and in p95-expressing tumors. Attempts to overcome resistance to anti-HER2 therapies with PI3K inhibitors, mTOR inhibitors, and CDK 4/6 inhibitors are an active area of research. In the future, biomarkers are needed to help predict which therapies patients may benefit from the most. We review the many new drugs in development, including those with novel mechanisms of action.

Biomimetic Nanoerythrosome-Coated Aptamer-DNA Tetrahedron/Maytansine Conjugates: pH-Responsive and Targeted Cytotoxicity for HER2-Positive Breast Cancer

DNA materials have emerged as potential nanocarriers for targeted cancer therapy to precisely deliver cargos with specific purposes. The short half-life and low bioavailability of DNA materials due to their interception by the reticuloendothelial system and blood clearance further limit their clinical translation. This study employs an HER2-targeted DNA-aptamer-modified DNA tetrahedron (HApt-tFNA) as a drug delivery system, and combines maytansine (DM1) to develop the HApt-DNA tetrahedron/DM1 conjugate (HApt-tFNA@DM1, HTD, HApDC) for targeted therapy of HER2-positive cancer. To optimize the pharmacokinetics and tumor-aggregation of HTD, a biomimetic camouflage is applied to embed HTD. The biomimetic camouflage is constructed by merging the erythrocyte membrane with pH-responsive functionalized synthetic liposomes, thus with excellent performance of drug delivery and tumor-stimulated drug release. The hybrid erythrosome-based nanoparticles show better inhibition of HER2-positive cancer than other drug formulations and exhibit superior biosafety. With the strengths of precise delivery, increased drug loading, sensitive tumor probing, and prolonged circulation time, the HApDC represents a promising nanomedicine to treat HER2-positive tumors. Notably, this study developsa dual-targeting nanoparticle by combining pH-sensitive camouflage and HApDC, initiating an important step toward the development and application of DNA-based medicine and biomimetic cell membrane materials in cancer treatment and other potential biological applications.

Evolution of complexity in non-viral oligonucleotide delivery systems: from gymnotic delivery through bioconjugates to biomimetic nanoparticles

From the early days of research on RNA biology and biochemistry, there was an interest to utilize this knowledge and RNA itself for therapeutic applications. Today, we have a series of oligonucleotide therapeutics on the market and many more in clinical trials. These drugs - exploit different chemistries of oligonucleotides, such as modified DNAs and RNAs, peptide nucleic acids (PNAs) or phosphorodiamidate morpholino oligomers (PMOs), and different mechanisms of action, such as RNA interference (RNAi), targeted RNA degradation, splicing modulation, gene expression and modification. Despite major successes e.g. mRNA vaccines developed against SARS-CoV-2 to control COVID-19 pandemic, development of therapies for other diseases is still limited by inefficient delivery of oligonucleotides to specific tissues and organs and often prohibitive costs for the final drug. This is even more critical when targeting multifactorial disorders and patient-specific biological variations. In this review, we will present the evolution of complexity of oligonucleotide delivery methods with focus on increasing complexity of formulations from gymnotic delivery to bioconjugates and to lipid nanoparticles in respect to developments that will enable application of therapeutic oligonucleotides as drugs in personalized therapies.

Non-Cationic RGD-Containing Protein Nanocarrier for Tumor-Targeted siRNA Delivery

Despite the recent successes in siRNA therapeutics, targeted delivery beyond the liver remains the major hurdle for the widespread application of siRNA in vivo. Current cationic liposome or polymer-based delivery agents are restricted to the liver and suffer from off-target effects, poor clearance, low serum stability, and high toxicity. In this study, we genetically engineered a non-cationic non-viral tumor-targeted universal siRNA nanocarrier (MW 26 KDa). This protein nanocarrier consists of three function domains: a dsRNA binding domain (dsRBD) (from human protein kinase R) for any siRNA binding, 18-histidine for endosome escape, and two RGD peptides at the N- and C-termini for targeting tumor and tumor neovasculature. We showed that cloned dual-RGD-dsRBD-18his (dual-RGD) protein protects siRNA against RNases, induces effective siRNA endosomal escape, specifically targets integrin α_vβ₃ expressing cells in vitro, and homes siRNA to tumors in vivo. The delivered siRNA leads to target gene knockdown in the cell lines and tumor xenografts with low toxicity. This multifunctional and biomimetic siRNA carrier is biodegradable, has low toxicity, is suitable for mass production by fermentation, and is serum stable, holding great potential to provide a widely applicable siRNA carrier for tumor-targeted siRNA delivery.

Aptamer grafted nanoparticle as targeted therapeutic tool for the treatment of breast cancer

Breast carcinomas repeat their number and grow exponentially making it extremely frequent malignancy among women. Approximately, 70-80% of early diagnosed or non-metastatic conditions are treatable while the metastatic cases are considered ineffective to treat with current ample amount of therapy. Target based anti-cancer treatment has been in the limelight for decades and is perceived significant consideration of scientists. Aptamers are the 'coming of age' therapeutic approach, selected using an appropriate tool from the library of sequences. Aptamers are non-immunogenic, stable, and high-affinity ligand which are poised to reach the clinical benchmark. With the heed in nanoparticle application, the delivery of aptamer to the specific site could be enhanced which also protects them from nuclease degradation. Moreover, nanoparticles due to robust structure, high drug entrapment, and modifiable release of cargo could serve as a successful candidate in the treatment of breast carcinoma. This review would showcase the method and modified method of selection of aptamers, aptamers that were able to make its way towards clinical trial and their targetability and selectivity towards breast cancers. The appropriate usage of aptamer-based biosensor in breast cancer diagnosis have also been discussed.

Highlights on selected growth factors and their receptors as promising anticancer drug targets

Growth factor receptors (GFRs) and receptor tyrosine kinases (RTK) are groups of proteins mediating a plethora of physiological processes, including cell growth, proliferation, survival, differentiation and migration. Under certain circumstances, expression of GFRs and subsequently their downstream kinase signaling are deregulated by genetic, epigenetic, and somatic changes leading to uncontrolled cell division in many human diseases, most notably cancer. Cancer cells rely on growth factors to sustain the increasing need to cell division and metabolic reprogramming through cancer-associated activating mutations of their receptors (i.e., GFRs). In this review, we highlight the recent advances of selected GFRs and their ligands (growth factors) in cancer with emphasis on structural and functional differences. We also interrogate how overexpression and/or hyperactivation of GFRs contribute to cancer initiation, development, progression, and resistance to conventional chemo- and radiotherapies. Novel approaches are being developed as anticancer agents to target growth factor receptors and their signaling pathways in different cancers. Here, we illustrate how the current knowledge of GFRs biology, and their ligands lead to development of targeted therapies to inhibit and/or block the activity of growth factors, GFRs and downstream kinases to treat diseases such as cancer.

Molecular dynamics simulation study of gold nanosheet as drug delivery vehicles for anti-HIV-1 aptamers

The adsorption process of three aptamers with gold nanosheet (GNS) as a drug carrier has been investigated with the help of molecular dynamics simulations. The sequencing of the considered aptamers are as (CUUCAUUGUAACUUCUCAUAAUUUCCCGAGGCUUUUACUUUCGGGGUCCU) and (CCGGGUCGUCCCCUACGGGGACUAAAGACUGUGUCCAACCGCCCUCGCCU) for AP1 and AP2, respectively. AP3 is a muted version of AP1 in which nucleotide positions 4, 6, 18, 28 and 39 have C4A, U6G, A18G, G28A, and U39C mutations. At positions 24, and 40, a deletion mutation is seen to eliminate U24 and U40 bases. These aptamers are inhibitors for HIV-1 protease and can be candidates as potential pharmaceutics for treatment of AIDS in the future. The interactions between considered aptamers and GNS have been analyzed in detail with help of structural and energetic properties. These analyses showed that all three aptamers could well adsorb on GNS. Overall, the final results show that the adsorption of AP2 on the GNS is more favorable than other considered ones and consequently GNS can be considered as a device in order to immobilize these aptamers.

The biological applications of DNA nanomaterials: current challenges and future directions

DNA, a genetic material, has been employed in different scientific directions for various biological applications as driven by DNA nanotechnology in the past decades, including tissue regeneration, disease prevention, inflammation inhibition, bioimaging, biosensing, diagnosis, antitumor drug delivery, and therapeutics. With the rapid progress in DNA nanotechnology, multitudinous DNA nanomaterials have been designed with different shape and size based on the classic Watson-Crick base-pairing for molecular self-assembly. Some DNA materials could functionally change cell biological behaviors, such as cell migration, cell proliferation, cell differentiation, autophagy, and anti-inflammatory effects. Some single-stranded DNAs (ssDNAs) or RNAs with secondary structures via self-pairing, named aptamer, possess the ability of targeting, which are selected by systematic evolution of ligands by exponential enrichment (SELEX) and applied for tumor targeted diagnosis and treatment. Some DNA nanomaterials with three-dimensional (3D) nanostructures and stable structures are investigated as drug carrier systems to delivery multiple antitumor medicine or gene therapeutic agents. While the functional DNA nanostructures have promoted the development of the DNA nanotechnology with innovative designs and preparation strategies, and also proved with great potential in the biological and medical use, there is still a long way to go for the eventual application of DNA materials in real life. Here in this review, we conducted a comprehensive survey of the structural development history of various DNA nanomaterials, introduced the principles of different DNA nanomaterials, summarized their biological applications in different fields, and discussed the current challenges and further directions that could help to achieve their applications in the future.

Photodynamic Therapy for the Treatment and Diagnosis of Cancer-A Review of the Current Clinical Status

Photodynamic therapy (PDT) has been used as an anti-tumor treatment method for a long time and photosensitizers (PS) can be used in various types of tumors. Originally, light is an effective tool that has been used in the treatment of diseases for ages. The effects of combination of specific dyes with light illumination was demonstrated at the beginning of 20th century and novel PDT approaches have been developed ever since. Main strategies of current studies are to reduce off-target effects and improve pharmacokinetic properties. Given the high interest and vast literature about the topic, approval of PDT as the first drug/device combination by the FDA should come as no surprise. PDT consists of two stages of treatment, combining light energy with a PS in order to destruct tumor cells after activation by light. In general, PDT has fewer side effects and toxicity than chemotherapy and/or radiotherapy. In addition to the purpose of treatment, several types of PSs can be used for diagnostic purposes for tumors. Such approaches are called photodynamic diagnosis (PDD). In this Review, we provide a general overview of the clinical applications of PDT in cancer, including the diagnostic and therapeutic approaches. Assessment of PDT therapeutic efficacy in the clinic will be discussed, since identifying predictors to determine the response to treatment is crucial. In addition, examples of PDT in various types of tumors will be discussed. Furthermore, combination of PDT with other therapy modalities such as chemotherapy, radiotherapy, surgery and immunotherapy will be emphasized, since such approaches seem to be promising in terms of enhancing effectiveness against tumor. The combination of PDT with other treatments may yield better results than by single treatments. Moreover, the utilization of lower doses in a combination therapy setting may cause less side effects and better results than single therapy. A better understanding of the effectiveness of PDT in a combination setting in the clinic as well as the optimization of such complex multimodal treatments may expand the clinical applications of PDT.

Utility of Multivalent Aptamers to Develop Nanoscale DNA Devices against Surface Receptors

DNA nanotechnology is undergoing rapid progress in the assembly of functional devices with biological relevance. In particular, currently, the research attention is more focused on the application of nanodevices at the interface of chemistry and biology, on the cell membrane where protein receptors communicate with the extracellular environment. This review explores the use of multivalent nucleic acid ligands termed aptamers in the design of DNA-based nanodevices to probe cellular interactions followed by a perspective on the untapped utility of XNA and UBP nanotechnology in designing functional nanomaterials with broader structural space.

A human epidermal growth factor receptor 3/heregulin interaction inhibitor aptamer discovered using SELEX

The interaction of human epidermal growth factor receptor 3 (HER3) and heregulin (HRG) is involved in resistance to human epidermal growth factor receptor 2 (HER2)-targeted cancer treatment, such as therapies using anti-HER2 monoclonal antibody. Therefore, inhibition of the HER3/HRG interaction is potentially valuable therapeutic target for cancer treatment. In this study, we used in vitro selection, also known as systematic evolution of ligands by exponential enrichment (SELEX) against the extracellular domain of human HER3, and discovered a novel RNA aptamer. Pull-down and bio-layer interferometry assays showed that RNA aptamer discovered specifically bound to HER3 with a dissociation constant (K_D) of 700 nM. Pull-down assays using chemiluminescence detection also revealed that the HER3-binding RNA aptamer inhibited interactions between HER3 and human HRG. These results indicated that the novel HER3-binding RNA aptamer has potential to be used as basic tool in a range of applications involving HER3/HRG interactions, including research, therapeutic, and diagnostic applications.

Bispecific Antibody Molecule Inhibits Tumor Cell Proliferation More Efficiently Than the Two-Molecule Combination

Background

Monoclonal antibodies (mAbs) have proved to be a valuable tool for the treatment of different cancer types. However, clinical use of an increasing number of mAbs, have also highlighted limitations with monotherapy for cancers, in particular for such with more complex mechanisms, requiring action on additional molecules or pathways, or for cancers quickly acquiring resistance following monotherapy. An example for the latter is the mAb trastuzumab, FDA approved for treatment of metastatic gastric carcinoma. To circumvent this, researchers have reported synergistic, anti-proliferative effects by combination targeting of HER2 and EGFR by trastuzumab and the EGFR-targeting mAb Cetuximab overcoming trastuzumab resistance.

Methods

Maintaining the proven functionality of trastuzumab, we have designed bi-specific antibody molecules, called AffiMabs, by fusing an EGFR-targeting Affibody molecule to trastuzumab’s heavy or light chains. Having confirmed binding to EGFR and Her2 and cytotoxicity of our AffiMabs, we analyzed apoptosis rate, receptor surface levels, phosphorylation levels of receptors and associated signaling pathways as well as differentially expressed genes on transcriptome level with the aim to elucidate the mode of action of our AffiMabs.

Results

The AffiMabs are able to simultaneously bind HER2 and EGFR and show increased cytotoxic effect compared to the original trastuzumab therapeutic molecule and, more importantly, even to the combination of trastuzumab and EGFR-targeting Affibody molecule. Analyzing the mode of action, we could show that bi-specific AffiMabs lead to reduced surface receptor levels and a downregulation of cell cycle associated genes on transcriptome level.

Conclusion

Our study shows that transcriptome analysis can be used to validate the choice of receptor targets and guide the design of novel multi-specific molecules. The inherent modularity of the AffiMab format renders it readily applicable to other receptor targets.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40268-021-00339-2.

Analysis of transient membrane protein interactions by single-molecule diffusional mobility shift assay

Various repertoires of membrane protein interactions determine cellular responses to diverse environments around cells dynamically in space and time. Current assays, however, have limitations in unraveling these interactions in the physiological states in a living cell due to the lack of capability to probe the transient nature of these interactions on the crowded membrane. Here, we present a simple and robust assay that enables the investigation of transient protein interactions in living cells by using the single-molecule diffusional mobility shift assay (smDIMSA). Utilizing smDIMSA, we uncovered the interaction profile of EGFR with various membrane proteins and demonstrated the promiscuity of these interactions depending on the cancer cell line. The transient interaction profile obtained by smDIMSA will provide critical information to comprehend the crosstalk among various receptors on the plasma membrane.

Fabrication of deferasirox-decorated aptamer-targeted superparamagnetic iron oxide nanoparticles (SPION) as a therapeutic and magnetic resonance imaging agent in cancer therapy

In the current study, the synthesis of a theranostic platform composed of superparamagnetic iron oxide nanoparticles (SPION)-deferasirox conjugates targeted with AS1411 DNA aptamer was reported. In this regard, SPION was amine-functionalized by (3-aminopropyl)trimethoxysilane (ATPMS), and then deferasirox was covalently conjugated onto its surface. Finally, to provide guided drug delivery to cancerous tissue, AS1411 aptamer was conjugated to the complex of SPION-deferasirox. The cellular toxicity assay on CHO, C-26 and AGS cell lines verified higher cellular toxicity of targeted complex in comparison with non-targeted one. The evaluation of in vivo tumor growth inhibitory effect in C26 tumor-bearing mice illustrated that the aptamer-targeted complex significantly enhanced the therapeutic outcome in comparison with both non-targeted complex and free drug. The diagnostic capability of the prepared platform was also evaluated implementing C26-tumor-bearing mice. Obtained data confirmed higher tumor accumulation and higher tumor residence time for targeted complex through MRI imaging due to the existence of SPION as a contrast agent in the core of the prepared complex. The prepared multimodal theranostic system provides a safe and effective platform for fighting against cancer.

Multiwalled carbon nanotubes co-delivering sorafenib and epidermal growth factor receptor siRNA enhanced tumor-suppressing effect on liver cancer

OBJECTIVE

This study aimed to investigate the effects of multiwalled carbon nanotubes (MWNTs) co-delivering sorafenib (Sor) and epidermal growth factor receptor (EGFR) siRNA (MWNT/Sor/siRNA) on tumor growth in liver cancer (LC).

RESULTS

MWNT/Sor/siRNA was proved to possess increased Sor release, high siRNA stability, and enhanced cellular uptake. In addition, MWNT treatment has few effects on cell proliferation and apoptosis in HepG2 cells; however, MWNT/Sor/siRNA treatment significantly inhibited clone number and induced cell apoptosis, which shows a more favorable antitumor effect than MWNT/Sor and free Sor and free siRNA in HepG2 cells. Moreover MWNT/Sor/siRNA treatment has the most significant antitumor effect in vivo.

CONCLUSIONS

MWNT/Sor/siRNA exhibited a superior antitumor effect in vitro and in vivo.

METHODS

The MWNT/Sor and MWNT/Sor/siRNA were prepared, and then the morphologies of MWNT/Sor/siRNA were analyzed. In vitro Sor release assay, siRNA stability and cellular uptake of MWNT/Sor/siRNA were performed as well. Next, the effects of MWNT, free Sor, free siRNA, MWNT/Sor and MWNT/Sor/siRNA were evaluated by colony-forming assay, and cell apoptosis assay in HepG2 cells. Meanwhile, the level of EGFR and proteins associated with apoptosis was tested. Furthermore, the anti-tumor effects of MWNT/Sor/siRNA on LC xenograft mice were also unraveled.

Progress in Biomedical Applications of Tetrahedral Framework Nucleic Acid-Based Functional Systems

The past decades have witnessed the development of DNA nanotechnology and the emergence of various spatial DNA nanostructures, from two-dimensions to three-dimensions. The typical example is the tetrahedral framework nucleic acid (tFNA). In this review, we summarize the progress in fabrication, modification of tFNA-based functional systems and their potentials in biomedical applications. Through a one-step assembly process, tFNA is synthesized via four single stranded DNAs with three short sequences complementary to the other sequence of another single strand. Characterizations including polyacrylamide gel electrophoresis, atomic force microscopy, and dynamic light scattering measurement show tFNA as a pyramid-like nanostructure with the size of around 10 nm. Feathered with intrinsic biocompatibility and satisfactory cellular membrane permeability, the first generation of tFNA shows promising capacities in regulating cell biological behavior, promoting tissue regeneration, and immunomodulation. Along with excellent editability and relative biostability in complicated conditions, tFNA could be modified via hanging functional domains on the vertex or side arm and incorporating small-molecular-weight drugs to form the second generation, for reversing multidrug resistance in tumor cells or microorganisms, target therapy, anticancer and antibacterial treatments. The third generation of tFNA is currently tried via a multistep assembly process for stimuli-response and precise drug release. Although tFNAs show promising potentials in cargo delivery, massive efforts still need to be made to improve biostability, maximal load, and structural controllability.

Kinome scale profiling of venom effects on cancer cells reveals potential new venom activities

The search for novel and relevant cancer therapeutics is continuous and ongoing. Cancer adaptations, resulting in therapeutic treatment failures, fuel this continuous necessity for new drugs to novel targets. Recently, researchers have started to investigate the effect of venoms and venom components on different types of cancer, investigating their mechanisms of action. Receptor tyrosine kinases (RTKs) comprise a family of highly conserved and functionally important druggable targets for cancer therapy. This research exploits the novelty of complex venom mixtures to affect phosphorylation of the epidermal growth factor receptor (EGFR) and related RTK family members, dually identifying new activities and unexplored avenues for future cancer and venom research. Six whole venoms from diverse species taxa, were evaluated for their ability to illicit changes in the phosphorylated expression of a panel of 49 commonly expressed RTKs. The triple negative breast cancer cell line MDA-MB-468 was treated with optimised venom doses, pre-determined by SDS PAGE and Western blot analysis. The phosphorylated expression levels of 49 RTKs in response to the venoms were assessed with the use of Human Phospho-RTK Arrays and analysed using ImageLab 5.2.1 analysis software (BioRad). Inhibition of EGFR phosphorylation occurred with treatment of venom from Acanthoscurria geniculata (Theraphosidae), Heterometrus swammerdami (Scorpionidae), Crotalus durissus vegrandis (Crotalidae) and Naja naja (Elapidae). Western green mamba Dendroaspis viridis venom increased EGFR phosphorylation. Eph, HGFR and HER were the most affected receptor families by venoms. Whilst the importance of these changes in terms of effect on MDA-MB-468 cells' long-term viability and functionality are still unclear, the findings present exciting opportunities for further investigation as potential drug targets in cancer and as tools to understand better how these pathways interact.

A bispecific circular aptamer tethering a built-in universal molecular tag for functional protein delivery

Chemically engineering endogenous amino acids with a molecular tag is one of the most common routes of artificially functionalizing proteins for identification or cellular delivery. However, it is challenging to make conjugation efficient, facile and productive as well as avoiding a high chance of deactivation of the functional proteins. Here we present a new and straightforward design to specifically tether the distinct six polyhistidine tag, terminally expressed on protein cargoes and cellular membrane proteins by using bispecific circular aptamers (bc-apts). The anti-His tag aptamer on one end of the bc-apt can easily recognize the biorthogonal six polyhistidine tag (His tag) on functional proteins like EGFP or RNase A. Meanwhile, a cell-specific aptamer, sgc8, on the other end efficiently facilitates the targeted delivery of functional proteins, improving their overall bioactivity in the cellular milieu by around 4 fold. Therefore, the nuclease-resistant bc-apt is a promising molecular tethering reagent to enable the noncovalent crosslink between live diseased cells and His tag protein cargoes.

Dual-targeted therapy in HER2-positive breast cancer cells with the combination of carbon dots/HER3 siRNA and trastuzumab

Dual-targeted therapy in HER2-positive breast cancer cells with the combination of carbon dots/HER3 siRNA and trastuzumab resulted in enhanced antitumor activity, which overcomes the resistance to trastuzumab monotherapy. Herein, we have developed branched polyethylenimine-functionalized carbon dot (BP-CD) nanocarriers, which exhibited efficient green fluorescent protein gene delivery and expression. The positively charged BP-CDs allowed for effective nucleic acid binding and displayed a highly efficient small interfering RNA (siRNA)-mediated delivery targeting of cancer cells. The transfection of BP-CDs and HER3 siRNA complexes down-regulated HER3 protein expression and induced significant cell growth inhibition in BT-474 cells. BP-CDs/HER3 siRNA complexes induced cell death of BT-474 cells through G0/G1 cell cycle arrest and apoptosis. The combined treatment of BP-CDs/HER3 siRNA complexes and trastuzumab caused greater cell growth suppression in BT-474 cells when compared to either agent alone. The findings suggest that this dual-targeted therapy with the combination of BP-CDs/HER3 siRNA and trastuzumab represents a promising approach in breast cancer.

Design, fabrication and applications of tetrahedral DNA nanostructure-based multifunctional complexes in drug delivery and biomedical treatment

Although organic nanomaterials and inorganic nanoparticles possess inherent flexibility, facilitating functional modification, increased intracellular uptake and controllable drug release, their underlying cytotoxicity and lack of specificity still cause safety concerns. Owing to their merits, which include natural biocompatibility, structural stability, unsurpassed programmability, ease of internalization and editable functionality, tetrahedral DNA nanostructures show promising potential as an alternative vehicle for drug delivery and biomedical treatment. Here, we describe the design, fabrication, purification, characterization and potential biomedical applications of a self-assembling tetrahedral DNA nanostructure (TDN)-based multifunctional delivery system. First, relying on Watson-Crick base pairing, four single DNA strands form a simple and typical pyramid structure via one hybridization step. Then, the protocol details four different modification approaches, including replacing a short sequence of a single DNA strand by an antisense peptide nucleic acid, appending an aptamer to the vertex, direct incubation with small-molecular-weight drugs such as paclitaxel and wogonin and coating with protective agents such as cationic polymers. These modified TDN-based complexes promote the intracellular uptake and biostability of the delivered molecules, and show promise in the fields of targeted therapy, antibacterial and anticancer treatment and tissue regeneration. The entire duration of assembly and characterization depends on the cargo type and modification method, which takes from 2 h to 3 d.