Improving vascular maturation using noncoding RNAs increases antitumor effect of chemotherapy

MicroRNA-155 and its exosomal form: Small pieces in the gastrointestinal cancers puzzle

Gastrointestinal (GI) cancers are common cancers that are responsible for a large portion of global cancer fatalities. Due to this, there is a pressing need for innovative strategies to identify and treat GI cancers. MicroRNAs (miRNAs) are short ncRNAs that can be considered either cancer-causing or tumor-inhibiting molecules. MicroRNA-155, also known as miR-155, is a vital regulator in various cancer types. This miRNA has a carcinogenic role in a variety of gastrointestinal cancers, including pancreatic, colon, and gastric cancers. Since the abnormal production of miR-155 has been detected in various malignancies and has a correlation with increased mortality, it is a promising target for future therapeutic approaches. Moreover, exosomal miR-155 associated with tumors have significant functions in communicating between cells and establishing the microenvironment for cancer in GI cancers. Various types of genetic material, such as specifically miR-155 as well as proteins found in cancer-related exosomes, have the ability to be transmitted to other cells and have a function in the advancement of tumor. Therefore, it is critical to conduct a review that outlines the diverse functions of miR-155 in gastrointestinal malignancies. As a result, we present a current overview of the role of miR-155 in gastrointestinal cancers. Our research highlighted the role of miR-155 in GI cancers and covered critical issues in GI cancer such as pharmacologic inhibitors of miRNA-155, miRNA-155-assosiated circular RNAs, immune-related cells contain miRNA-155. Importantly, we discussed miRNA-155 in GI cancer resistance to chemotherapy, diagnosis and clinical trials. Furthermore, the function of miR-155 enclosed in exosomes that are released by cancer cells or tumor-associated macrophages is also covered.

Liposomal Phenylephrine Nanoparticles Enhance the Antitumor Activity of Intratumoral Chemotherapy in a Preclinical Model of Melanoma

Intratumoral injection of anticancer agents has limited efficacy and is not routinely used for most cancers. In this study, we aimed to improve the efficacy of intratumoral chemotherapy using a novel approach comprising peri-tumoral injection of sustained-release liposomal nanoparticles containing phenylephrine, which is a potent vasoconstrictor. Using a preclinical model of melanoma, we have previously shown that systemically administered (intravenous) phenylephrine could transiently shunt blood flow to the tumor at the time of drug delivery, which in turn improved antitumor responses. This approach was called dynamic control of tumor-associated vessels. Herein, we used liposomal phenylephrine nanoparticles as a "local" dynamic control strategy for the B16 melanoma. Local dynamic control was shown to increase the retention and exposure time of tumors to intratumorally injected chemotherapy (melphalan). C57BL/6 mice bearing B16 tumors were treated with intratumoral melphalan and peri-tumoral injection of sustained-release liposomal phenylephrine nanoparticles (i.e., the local dynamic control protocol). These mice had statistically significantly improved antitumor responses compared to melphalan alone (p = 0.0011), whereby 58.3% obtained long-term complete clinical response. Our novel approach of local dynamic control demonstrated significantly enhanced antitumor efficacy and is the subject of future clinical trials being designed by our group.

Human intravital microscopy in the study of sarcomas: an early trial of feasibility

Sarcomas comprise a vast and heterogenous group of rare tumors. Because of their diversity, it is challenging to study sarcomas as a whole with regard to their biological and molecular characteristics. This diverse set of tumors may also possess differences related to their tumor-associated vasculature, which in turn may impact the ability to deliver systemic therapies (e.g., chemotherapy, targeted therapies, and immunotherapy). Consequently, response to systemic treatment may also be variable as these depend on the ability of the therapy to reach the tumor target via the tumor-associated vasculature. There is a paucity of data regarding sarcoma-related tumor vessels, likely in part to the rarity and heterogeneity of this cancer as well as the previously limited ability to image tumor-associated vessels in real time. Our group has previously utilized confocal fluorescent imaging technology to observe and characterize tumor-associated vessels in real time during surgical resection of tumors, including cutaneous melanoma and carcinomatosis implants derived from gastrointestinal, gynecological, or primary peritoneal (e.g., mesothelioma) tumors. Our prior studies have demonstrated the feasibility of real-time, human intravital microscopy in the study of these tumor types, leading to early but important new data regarding tumor vessel characteristics and their potential implications on drug delivery and efficacy. In this brief report, we present our latest descriptive findings in a cohort of patients with sarcoma who underwent surgical resection and real-time, intravital microscopy of their tumors. Overall, intravital imaging was feasible during the surgical resection of large sarcomas.

Clinical trial registrations

ClinicalTrials.gov, identifier NCT03517852; ClinicalTrials.gov, identifier NCT03823144.

The Interplay between MicroRNAs and the Components of the Tumor Microenvironment in B-Cell Malignancies

An increased focus is being placed on the tumorigenesis and contexture of tumor microenvironment in hematopoietic and solid tumors. Despite recent clinical revolutions in adoptive T-cell transfer approaches and immune checkpoint blockade, tumor microenvironment is a major obstacle to tumor regression in B-cell malignancies. A transcriptional alteration of coding and non-coding RNAs, such as microRNAs (miRNAs), has been widely demonstrated in the tumor microenvironment of B-cell malignancies. MiRNAs have been associated with different clinical-biological forms of B-cell malignancies and involved in the regulation of B lymphocyte development, maturation, and function, including B-cell activation and malignant transformation. Additionally, tumor-secreted extracellular vesicles regulate recipient cell functions in the tumor microenvironment to facilitate metastasis and progression by delivering miRNA contents to neighboring cells. Herein, we focus on the interplay between miRNAs and tumor microenvironment components in the different B-cell malignancies and its impact on diagnosis, proliferation, and involvement in treatment resistance.

miR-155 in cancer drug resistance and as target for miRNA-based therapeutics

Small non-coding microRNAs (miRNAs) are instrumental in physiological processes, such as proliferation, cell cycle, apoptosis, and differentiation, processes which are often disrupted in diseases like cancer. miR-155 is one of the best conserved and multifunctional miRNAs, which is mainly characterized by overexpression in multiple diseases including malignant tumors. Altered expression of miR-155 is found to be associated with various physiological and pathological processes, including hematopoietic lineage differentiation, immune response, inflammation, and tumorigenesis. Furthermore, miR-155 drives therapy resistance mechanisms in various tumor types. Therefore, miR-155-mediated signaling pathways became a potential target for the molecular treatment of cancer. In this review, we summarize the current findings of miR-155 in hematopoietic lineage differentiation, the immune response, inflammation, and cancer therapy resistance. Furthermore, we discuss the potential of miR-155-based therapeutic approaches for the treatment of cancer.

X-Aptamer Technology Identifies C4A and ApoB in Blood as Potential Markers for Schizophrenia

The field of proteomics is rapidly gaining territory as a promising alternative to genomic approaches in the efforts to unravel the complex molecular mechanisms underlying schizophrenia and other psychiatric disorders. X-aptamer tech-nology has emerged as a novel proteomic approach for high-sensitivity analyses, and we hypothesized that this technology would identify unique molecular signatures in plasma samples from schizophrenia patients (n = 60) compared to controls (n = 20). Using a combinatorial library of X-aptamer beads, we developed a two-color flow cytometer-based approach to identify specific X-aptamers that bound with high specificity to each target group. Based on this, we synthesized two unique X-aptamer sequences, and specific proteins pulled down from the patient and control groups by these X-aptamers were identified by mass spectrometry. We identified two protein biomarkers, complement component C4A and ApoB, upregulated in plasma samples from schizophrenia patients. ELISA validation suggested that the observed differences in C4 levels in patients are likely due to the presence of the illness itself, while ApoB may be a marker of antipsychotic-induced alterations. These studies highlight the utility of the X-aptamer technology in the identification of biomarkers for schizophrenia that will advance our understanding of the pathophysiological mechanisms of this disorder.

Dual Suppressive Effect of miR-34a on the FOXM1/eEF2-Kinase Axis Regulates Triple-Negative Breast Cancer Growth and Invasion

Purpose: Recent studies indicated that dysregulation of noncoding RNAs (ncRNA) such as miRNAs is involved in pathogenesis of various human cancers. However, the molecular mechanisms underlying miR-34a are not fully understood in triple-negative breast cancer (TNBC).Experimental Design: We performed in vitro functional assays on TNBC cell lines to investigate the role of miR-34a in FOXM1/eEF2K signaling axis. TNBC tumor xenograft models were used for in vivo therapeutic delivery of miR-34a.Results: In this study, we investigated the role of p53-driven ncRNA miR-34a and found that miR-34a is associated with significantly longer patient survival in TNBC and inversely correlated with levels of proto-oncogenic eEF2K, which was associated with significantly shorter overall patient survival. We showed that miR-34a directly binds to the 3'-untranslated region of eEF2K and FOXM1 mRNAs and suppresses their expression, leading to inhibition of TNBC cell proliferation, motility, and invasion. Notably, restoring miR-34a expression recapitulated the effects of inhibition of eEF2K and FOXM1, the transcription factor for eEF2K and the direct target of p53, in TNBC cell lines, whereas overexpression of eEF2K and FOXM1 rescued the effects and signaling pathways mediated by miR-34a. Moreover, in vivo therapeutic delivery of miR-34a nanoparticles by systemic intravenous administration delayed tumor growth of two different orthotopic TNBC tumor xenograft models by inhibiting eEF2K and FOXM1, intratumoral proliferation and angiogenesis, and inducing apoptosis.Conclusions: Overall, our findings provide new insights into the tumor suppressor role of miR-34a by dual-targeting of FOXM1/eEF2K signaling axis and suggest that miR-34a-based gene therapy may be a potential therapeutic strategy in TNBC. Clin Cancer Res; 24(17); 4225-41. ©2018 AACR.

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.

Cell-to-cell communication: microRNAs as hormones

Mammalian cells can release different types of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies. Accumulating evidence suggests that EVs play a role in cell-to-cell communication within the tumor microenvironment. EVs' components, such as proteins, noncoding RNAs [microRNAs (miRNAs), and long noncoding RNAs (lncRNAs)], messenger RNAs (mRNAs), DNA, and lipids, can mediate paracrine signaling in the tumor microenvironment. Recently, miRNAs encapsulated in secreted EVs have been identified in the extracellular space. Mature miRNAs that participate in intercellular communication are released from most cells, often within EVs, and disseminate through the extracellular fluid to reach remote target cells, including tumor cells, whose phenotypes they can influence by regulating mRNA and protein expression either as tumor suppressors or as oncogenes, depending on their targets. In this review, we discuss the roles of miRNAs in intercellular communication, the biological function of extracellular miRNAs, and their potential applications for diagnosis and therapeutics. We will give examples of miRNAs that behave as hormones.

Development of Phosphorothioate DNA and DNA Thioaptamers

Nucleic acid aptamers are short RNA- or DNA-based affinity reagents typically selected from combinatorial libraries to bind to a specific target such as a protein, a small molecule, whole cells or even animals. Aptamers have utility in the development of diagnostic, imaging and therapeutic applications due to their size, physico-chemical nature and ease of synthesis and modification to suit the application. A variety of oligonucleotide modifications have been used to enhance the stability of aptamers from nuclease degradation in vivo. The non-bridging oxygen atoms of the phosphodiester backbones of RNA and DNA aptamers can be substituted with one or two sulfur atoms, resulting in thioaptamers with phosphorothioate or phosphorodithioate linkages, respectively. Such thioaptamers are known to have increased binding affinity towards their target, as well as enhanced resistance to nuclease degradation. In this review, we discuss the development of phosphorothioate chemistry and thioaptamers, with a brief review of selection methods.

RNA nanoparticles harboring annexin A2 aptamer can target ovarian cancer for tumor-specific doxorubicin delivery

A novel modified nucleic acid nanoparticle harboring an annexin A2 aptamer for ovarian cancer cell targeting and a GC rich sequence for doxorubicin loading is designed and constructed. The system utilizes a highly stable three-way junction (3WJ) motif from phi29 packaging RNA as a core structure. A phosphorothioate-modified DNA aptamer targeting annexin A2, Endo28, was conjugated to one arm of the 3WJ. The pRNA-3WJ motif retains correct folding of attached aptamer, keeping its functions intact. It is of significant utility for aptamer-mediated targeted delivery. The DNA/RNA hybrid nanoparticles remained intact after systemic injection in mice and strongly bound to tumors with little accumulation in healthy organs 6 h post-injection. The Endo28-3WJ-Sph1/Dox intercalates selectively enhanced toxicity to annexin A2 positive ovarian cancer cells in vitro. The constructed RNA/DNA hybrid nanoparticles can potentially enhance the therapeutic efficiency of doxorubicin at low doses for ovarian cancer treatment through annexin A2 targeted drug delivery.

The Pleiotropic Role of L1CAM in Tumor Vasculature

Angiogenesis, the formation of new vessels, is a key step in the development, invasion, and dissemination of solid tumors and, therefore, represents a viable target in the context of antitumor therapy. Indeed, antiangiogenic approaches have given promising results in preclinical models and entered the clinical practice. However, in patients, the results obtained so far with antiangiogenic drugs have not completely fulfilled expectations, especially because their effect has been transient with tumors developing resistance and evasion mechanisms. A better understanding of the mechanisms that underlie tumor vascularization and the functional regulation of cancer vessels is a prerequisite for the development of novel and alternative antiangiogenic treatments. The L1 cell adhesion molecule (L1CAM), a cell surface glycoprotein previously implicated in the development and plasticity of the nervous system, is aberrantly expressed in the vasculature of various cancer types. L1CAM plays multiple pro-angiogenic roles in the endothelial cells of tumor-associated vessels, thus emerging as a potential therapeutic target. In addition, L1CAM prevents the maturation of cancer vasculature and its inhibition promotes vessel normalization, a process that is thought to improve the therapeutic response of tumors to cytotoxic drugs. We here provide an overview on tumor angiogenesis and antiangiogenic therapies and summarize the current knowledge on the biological role of L1CAM in cancer vasculature. Finally, we highlight the clinical implications of targeting L1CAM as a novel antiangiogenic and vessel-normalizing approach.

Morph-X-Select: Morphology-based tissue aptamer selection for ovarian cancer biomarker discovery

High affinity aptamer-based biomarker discovery has the advantage of simultaneously discovering an aptamer affinity reagent and its target biomarker protein. Here, we demonstrate a morphology-based tissue aptamer selection method that enables us to use tissue sections from individual patients and identify high-affinity aptamers and their associated target proteins in a systematic and accurate way. We created a combinatorial DNA aptamer library that has been modified with thiophosphate substitutions of the phosphate ester backbone at selected 5´dA positions for enhanced nuclease resistance and targeting. Based on morphological assessment, we used image-directed laser microdissection (LMD) to dissect regions of interest bound with the thioaptamer (TA) library and further identified target proteins for the selected TAs. We have successfully identified and characterized the lead candidate TA, V5, as a vimentin-specific sequence that has shown specific binding to tumor vasculature of human ovarian tissue and human microvascular endothelial cells. This new Morph-X-Select method allows us to select high-affinity aptamers and their associated target proteins in a specific and accurate way, and could be used for personalized biomarker discovery to improve medical decision-making and to facilitate the development of targeted therapies to achieve more favorable outcomes.