Targeted Downregulation of MYC through G-quadruplex Stabilization by DNAi.

Modulating the expression or function of the enigmatic MYC protein has demonstrated efficacy in an array of cancer types and a marked potential therapeutic index and safety profile. Despite its high therapeutic value, specific and selective inhibitors or downregulating therapeutics have proven difficult to develop. In the current study, we expanded our work on a MYC promoter G-quadruplex (G4) stabilizing DNA clamp to develop an oligonucleotide interfering DNA (DNAi) therapeutic. We explored six DNAi for G4-stabilization through EMSA, DMS footprinting, and thermal stability studies, focusing on the DNAi 5T as the lead therapeutic. 5T, but not its scramble control 5Tscr, was then shown to enter the nucleus, modulate cell viability, and decrease MYC expression through G4-stabilization. DNAi 5T is thus described to be our lead DNAi, targeting MYC regulation through stabilization of the higher-order DNA G4 structure in the proximal promoter, and it is poised for further preclinical development as an anticancer therapeutic.

An aging mouse model of human chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is an age-dependent blood malignancy. Like many other age-dependent human diseases, laboratory animal research of CML uses young mice that do not factor in the influence of aging. To understand how aging may impact animal modeling of human age-dependent diseases, we established the first aging mouse model of human CML in BALB/c mice in the advanced age defined by 75% survival. This model was developed by noncytotoxic depletion of bone marrow lineage-positive cells followed by BCR-ABL retroviral transduction and transplantation. CML developed in aging mice shared many similarities to that in young mice, but had increased incidence of anemia that is often seen in human CML. Importantly, we showed that aging of both donor hematopoietic stem cells and recipient bone marrow niche impacted BCR-ABL mediated leukemogenesis and leukemia spectrum. Optimal CML induction relied on age-matching for donors and recipients, and cross-transplantation between young and old mice produced a mixture of different leukemia. Therefore, our model provides initial evidence of the feasibility and merit of CML modeling in aging mice and offers a new tool for future studies of CML stem cell drug resistance and therapeutic intervention in which aging would be taken into consideration as an influencing factor.

An emerging trend of rapid increase of leukemia but not all cancers in the aging population in the United States.

The "baby boomers" born in 1946-1964 in the United States (U.S.) started to reach the age of 65 in 2011, rapidly accelerating U.S. population aging. There are great public concerns about its impact on health care with anticipation of rising cancer incidences. We examined the incidences and deaths of leukemia and overall cancer in the U.S. from 1998 to 2018. The acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) incidences remained constant prior to 2011 but have climbed up substantially since then, and the chronic lymphocytic leukemia (CLL) incidence has increased continuously since 1998. The significant increase of myeloid leukemia and CLL incidences was strongly correlated with the U.S. population aging. The incidence of all cancers was increased in correlation with a small increase in aging population prior to 2011, but surprisingly has changed marginally since 2011, which was not significantly correlated with the accelerated population aging. We observed the most substantial decline of deaths with CML, whereas AML deaths continued to rise in the past 20 years. In conclusion, the overall cancer incidence was not increased as fast as previously feared with aging Americans; however, the incidences of myeloid leukemia and CLL significantly outpaced that of all cancers.

Cysteine-rich protein 61 regulates the chemosensitivity of chronic myeloid leukemia to imatinib mesylate through the nuclear factor kappa B/Bcl-2 pathway.

Although the targeted tyrosine kinase inhibitor imatinib mesylate (IM) has achieved significant responses against CML in the clinical setting, a small proportion of patients fail to respond to IM treatment and their disease continues to progress, indicating resistance to IM therapy. As a secreted extracellular matrix protein, cysteine-rich protein 61 (Cyr61) plays an important role in the resistance of solid tumors to chemotherapy, but its role in CML is unclear. In the present study, we observed that Cyr61 levels were upregulated in the plasma and bone marrow (BM) of patients with CML as well as in K562 cells. This upregulation of Cyr61 significantly decreased IM-induced cellular apoptosis of K562 cells through nuclear factor kappa B/B-cell lymphoma 2 pathways. Inhibition of Cyr61 restored the chemosensitivity of K562 cells to IM both in vitro and in vivo. Thus, our results showed for the first time that Cyr61 plays an important role in regulating the chemosensitivity of CML cells to IM, suggesting that selectively targeting Cyr61 directly or its relevant effector pathways may provide potential value in improving the clinical response of patients with CML to IM treatment.

Cyr61 decreases Cytarabine chemosensitivity in acute lymphoblastic leukemia cells via NF-κB pathway activation.

Elevated Cyr61 levels have been reported in various malignancies. Elevation of Cyr61 protein levels contributes to the proliferation, metastasis, and chemotherapy resistance of malignant cells. Previously, it was discovered that Cyr61 is elevated in both the plasma and the bone marrow supernatants of patients with acute lymphoblastic leukemia (ALL), promoting ALL cell survival. However, the role of Cyr61 in the chemotherapeutic resistance of ALL cells remains unknown. The aim of the current study was to investigate the role of Cyr61 in regulating ALL cell chemosensitivity to Ara­C. It was found that Cyr61 is overexpressed in bone marrow mononuclear cells from patients with ALL. Increased Cyr61 effectively decreased Ara­C­induced apoptosis of ALL cells, and its function was blocked by the use of the anti­Cyr61 monoclonal antibody 093G9. Furthermore, Cyr61 increased the level of Bcl­2 in Ara­C­treated ALL cells. Mechanistically, it was shown that Cyr61 affected ALL cell resistance to Ara­C partially via the NF­κB pathway. Taken together, the present study is the first, to the best of our knowledge, to reveal that Cyr61 is involved in ALL cell resistance through the NF­κB pathway. The findings support a functional role for Cyr61 in promoting chemotherapy resistance, suggesting that targeting Cyr61 directly or its relevant effector pathways may improve the clinical responses of patients with ALL.

Evaluation of platelet indices as diagnostic biomarkers for colorectal cancer.

Altered platelet indices, including platelet count (PC), mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT), have been found in various cancer types. This study aimed to evaluate the role of platelet indices as potential biomarkers for the diagnosis of colorectal cancer (CRC), and to assess the association between platelet indices and CRC clinicopathological characteristics. The study included 783 subjects with CRC, 463 subjects with colorectal adenomas (CA), and 689 control subjects from June 2015 to October 2017. All participants' clinicopathological characteristics were collected and analyzed. Here, we found that PC, MPV and PCT levels in CRC patients were significantly higher than those in CA patients and healthy participants (p < 0.001); however, PDW level in CRC patients was significantly higher than that in healthy participants while lower than that in CA patients. Receiver-operating characteristic (ROC) analysis indicated that combined detection of PCT and CEA appears to be a more effective marker to distinguish CRC patients from CA patients, with 70% sensitivity and 83% specificity. Among CRC patients, PC and PCT levels were associated with TNM stages and tumor size; MPV and PCT levels were associated with vascular invasion. Our findings suggest that altered PC, MPV and PCT levels might serve as potential biomarkers for the diagnosis and prognosis of CRC.

RAFT Polymerization for the Synthesis of Tertiary Amine-Based Diblock Copolymer Nucleic Acid Delivery Vehicles.

The synthesis and characterization of a family of nine pH-responsive, diblock copolymers designed to effectively deliver nucleic acids are reported. The stabilizing A block is comprised of an oligo(ethylene glycol) methyl ether methacrylate to impart water solubility. The cationic blocks of varying degrees of polymerization (DPs) are derived from three pH responsive, tertiary amine-containing methacrylates capable of complexing negatively charged nucleic acids. The cytotoxicity studies utilizing human embryonic kidney cells (HEK-293) and Michigan Cancer Foundation-7 (MCF-7) breast cancer cells indicate no decrease of cell viability with the diblock copolymers, with the exception of the two highest DPs of the cationic blocks with ethyl-substitutes tertiary amine. Gene knockdown experiments indicate high siRNA delivery and MYC gene knockdown in MCF-7 breast cancer cells for eight of the nine studied block copolymers. The results of the current study enable further development of the pH-responsive copolymer family for promising nucleic acid delivery vehicles applicable for clinical use.

Nucleic acid clamp-mediated recognition and stabilization of the physiologically relevant MYC promoter G-quadruplex.

The MYC proto-oncogene is upregulated, often at the transcriptional level, in ∼80% of all cancers. MYC's promoter is governed by a higher order G-quadruplex (G4) structure in the NHE III1 region. Under a variety of conditions, multiple isoforms have been described to form from the first four continuous guanine runs (G41-4) predominating under the physiologically relevant supercoiled conditions. In the current study, short oligonucleotides complementing the 5'- and 3'-regions flanking the G4 have been connected by an abasic linker to form G4 clamps, varying both linker length and G4 isoform being targeted. Clamp A with an 18 Šlinker was found to have marked affinity for its target isomer (G41-4) over the other major structures (G42-5 and G41-5, recognized by clamps B and C, respectively), and to be able to shift equilibrating DNA to foster greater G4 formation. In addition, clamp A, but not B or C, is able to modulate MYC promoter activity with a significant and dose-dependent effect on transcription driven by the Del4 plasmid. This linked clamp-mediated approach to G4 recognition represents a novel therapeutic mechanism with specificity for an individual promoter structure, amenable to a large array of promoters.

Two new anxiolytic phenanthrenes found in the medullae of Juncus effusus.

Six phenanthrenes, 2-methoxy-7-hydroxy-1-methyl-5-vinyl phenanthrene (1), juncusin (2), dehydroeffusol (3), juncusol (4), effusol (5), and dehydroeffusal (6), were isolated from the medullae of Juncus effusus L. Compounds 1 and 2 were identified as being new structures, and both of them showed anxiolytic activity at dosages of 10 and 2.5 mg/kg, respectively.