G-749, a novel FLT3 kinase inhibitor, can overcome drug resistance for the treatment of acute myeloid leukemia.

Aberrant activations of Fms-like tyrosine receptor kinase (FLT) 3 are implicated in the pathogenesis of 20% to 30% of patients with acute myeloid leukemia (AML). G-749 is a novel FLT3 inhibitor that showed potent and sustained inhibition of the FLT3 wild type and mutants including FLT3-ITD, FLT3-D835Y, FLT3-ITD/N676D, and FLT3-ITD/F691L in cellular assays. G-749 retained its inhibitory potency in various drug-resistance milieus such as patient plasma, FLT3 ligand surge, and stromal protection. Furthermore, it displayed potent antileukemic activity in bone marrow blasts from AML patients regardless of FLT3 mutation status, including those with little or only minor responses to AC220 or PKC412. Oral administration of G-749 yielded complete tumor regression and increased life span in animal models. Thus, G-749 appears to be a promising next-generation drug candidate for the treatment of relapsed and refractory AML patients with various FLT3-ITD/FLT3-TKD mutants and further shows the ability to overcome drug resistance.

ß-Catenin recognizes a specific RNA motif in the cyclooxygenase-2 mRNA 3'-UTR and interacts with HuR in colon cancer cells.

RNA-binding proteins regulate multiple steps of RNA metabolism through both dynamic and combined binding. In addition to its crucial roles in cell adhesion and Wnt-activated transcription in cancer cells, ß-catenin regulates RNA alternative splicing and stability possibly by binding to target RNA in cells. An RNA aptamer was selected for specific binding to ß-catenin to address RNA recognition by ß-catenin more specifically. Here, we characterized the structural properties of the RNA aptamer as a model and identified a ß-catenin RNA motif. Similar RNA motif was found in cellular RNA, Cyclooxygenase-2 (COX-2) mRNA 3'-untranslated region (3'-UTR). More significantly, the C-terminal domain of ß-catenin interacted with HuR and the Armadillo repeat domain associated with RNA to form the RNA-ß-catenin-HuR complex in vitro and in cells. Furthermore, the tertiary RNA-protein complex was predominantly found in the cytoplasm of colon cancer cells; thus, it might be related to COX-2 protein level and cancer progression. Taken together, the ß-catenin RNA aptamer was valuable for deducing the cellular RNA aptamer and identifying novel and oncogenic RNA-protein networks in colon cancer cells.

Optimal bilayer composites for temperature-tracking wireless electronics.

Modern silicone-based epidermal electronics engineered for body temperature sensing represent a pivotal development in the quest for advancing preventive medicine and enhancing post-surgical monitoring. While these compact and highly flexible electronics empower real-time monitoring in dynamic environments, a noteworthy limitation is the challenge in regulating the infiltration or obstruction of heat from the external environment into the surface layers of these electronics. The study presents a cost-effective temperature sensing solution by embedding wireless electronics in a multi-layered elastomeric composite to meet the dual needs of enhanced thermal insulation for encapsulation in contact with air and improved thermal conductivity for the substrate in contact with the skin. The encapsulating composite benefits from the inclusion of hollow silica microspheres, which reduce the thermal conductivity by 40%, while non-spherical aluminum nitride enhances the thermal conductivity of the substrate by 370%. The addition of particles to the respective composites inevitably leads to an increase in modulus. Two composite elements are engineered to coexist while maintaining a matching low modulus of 3.4 MPa and a stretchability exceeding 30%, all without compromising the optimized thermal properties. Consecutive thermal, electrical, and mechanical characterization confirms the sensor's capacity for precise body temperature monitoring during a single day's lifespan, while also assessing the influence of behavioral factors on body temperature.

Incorporation of SKI-G-801, a Novel AXL Inhibitor, With Anti-PD-1 Plus Chemotherapy Improves Anti-Tumor Activity and Survival by Enhancing T Cell Immunity.

A recently developed treatment strategy for lung cancer that combines immune checkpoint inhibitors with chemotherapy has been applied as a standard treatment for lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), and it has improved the outcomes of chemotherapy. Maintenance treatment with anti-PD-1 antibody (aPD-1) enhances the effect of immunochemical combination therapy and improves therapeutic efficacy, which contributes toward a significant improvement in patient survival rates. The AXL receptor tyrosine kinase (AXL), which is expressed in tumor cells, plays an essential role in the resistance of cancers to chemotherapy and immunotherapy, and stimulates signaling associated with epithelial-mesenchymal transition (EMT) in metastatic cancer. AXL is thus an attractive target for controlling resistance to anti-tumor therapies. In this study, we examined the effect of AXL inhibitors on immune activation and tumor growth in TC1 and C3PQ mouse tumor models, in the context of clinical immunotherapy/chemotherapy and maintenance treatment, using an aPD-1 with/without pemetrexed. To determine the optimal timing for administration of SKI-G-801, an AXL inhibitor, we investigated its anti-tumor effects based on inclusion at the immunochemotherapy and maintenance therapy stages. We also performed flow cytometry-based immune profiling of myeloid cells and lymphoid cells at different points in the treatment schedule, to investigate the immune activation and anti-tumor effects of the AXL inhibitor. The addition of SKI-G-801 to the immune checkpoint inhibitor and chemotherapy stage, as well as the maintenance therapy stage, produced the best anti-tumor results, and significant tumor growth inhibition was observed in both the TC1 and C3PQ models. Both models also exhibited increased proportion of effector memory helper T cells and increased expression of CD86+ macrophages. Especially, regulatory T cells were significantly reduced in the TC1 tumor model and there was an increase in central memory cytotoxic T cell infiltration and an increased proportion of macrophages with high CD80 expression in the C3PQ tumor model. These results suggest increased infiltration of T cells, consistent with previous studies using AXL inhibitors. It is expected that the results from this study will serve as a stepping stone for clinical research to improve the existing standard of care.

SKI-G-801, an AXL kinase inhibitor, blocks metastasis through inducing anti-tumor immune responses and potentiates anti-PD-1 therapy in mouse cancer models.

OBJECTIVES: AXL-mediated activation of aberrant tyrosine kinase drives various oncogenic processes and facilitates an immunosuppressive microenvironment. We evaluated the anti-tumor and anti-metastatic activities of SKI-G-801, a small-molecule inhibitor of AXL, alone and in combination with anti-PD-1 therapy. METHODS: In vitro pAXL inhibition by SKI-G-801 was performed in both human and mouse cancer cell lines. Immunocompetent mouse models of tumor were established to measure anti-metastatic potential of SKI-G-801. Furthermore, SKI-G-801, anti-PD-1 or their combination was administered as an adjuvant or neoadjuvant in the 4T1 tumor model to assess their potential for clinical application. RESULTS: SKI-G-801 robustly inhibited pAXL expression in various cell lines. SKI-G-801 alone or in combination with anti-PD-1 potently inhibited metastasis in B16F10 melanoma, CT26 colon and 4T1 breast models. SKI-G-801 inhibited the growth of B16F10 and 4T1 tumor-bearing mice but not immune-deficient mice. An antibody depletion assay revealed that CD8+ T cells significantly contributed to SKI-G-801-mediated survival. Anti-PD-1 and combination group were observed the increased CD8+Ki67+ and effector T cells and M1 macrophage and decreased M2 macrophage, and granulocytic myeloid-derived suppressor cell (G-MDSC) compared to the control group. The neoadjuvant combination of SKI-G-801 and anti-PD-1 therapy achieved superior survival benefits by inducing more profound T-cell responses in the 4T1 syngeneic mouse model. CONCLUSION: SKI-G-801 significantly suppressed tumor metastasis and growth by enhancing anti-tumor immune responses. Our results suggest that SKI-G-801 has the potential to overcome anti-PD-1 therapy resistance and allow more patients to benefit from anti-PD-1 therapy.

Use of RNA aptamers for the modulation of cancer cell signaling.

Aptamers are in vitro evolved molecules that bind to target proteins with high affinity and specificity by adapting three-dimensional structures upon binding. Because cancer cells exhibit the activation of signaling pathways that are not usually activated in normal cells, RNA aptamers against such a cancer cell-specific signal can be useful lead molecules for cancer gene therapy. The Wnt/beta-catenin signaling pathway plays important roles in a critical initiating event in the formation of various human cancers. Because mutations in beta-catenin have been found to be responsible for human tumorigenesis, beta-catenin is the molecular target for effective anticancer therapies. Here, we describe the selection of RNA aptamers against beta-catenin/T-Cell Factor (TCF) proteins and their intracellular expression as intramers. The RNA aptamers acted as central inhibitory players for multiple oncogenic functions of beta-catenin in colon cancer cells. These data provide the proof-of-principle for the use of RNA aptamers for an effective anticancer gene therapy.

beta-catenin regulates multiple steps of RNA metabolism as revealed by the RNA aptamer in colon cancer cells.

Nuclear beta-catenin forms a transcription complex with TCF-4, which is implicated in colon cancer development and progression. Recently, we and others have shown that beta-catenin could be a regulator of RNA splicing and it also stabilizes the cyclooxygenase-2 (COX-2) mRNA. Here, we further explored the role of beta-catenin in the RNA metabolism in colon cancer cells. To specifically modulate the subcellular functions of beta-catenin, we expressed the RNA aptamer in the form of RNA intramers with unique cellular localizations. The nucleus-expressed RNA intramer proved to be effective in reducing the protein-protein interaction between beta-catenin and TCF-4, thus shown to be a specific regulator of beta-catenin-activated transcription. It could also regulate the alternative splicing of E1A minigene in diverse colon cancer cell lines. In addition, we tested whether beta-catenin could stabilize any other mRNAs and found that cyclin D1 mRNA was also bound and stabilized by beta-catenin. Significantly, the cytoplasm-expressed RNA intramer reverted the beta-catenin-induced COX-2 and cyclin D1 mRNA stabilization. We show here that beta-catenin regulated multiple steps of RNA metabolism in colon cancer cells and might be the protein factor coordinating RNA metabolism. We suggest that the RNA intramers could provide useful ways for inhibiting beta-catenin-mediated transcription and RNA metabolism, which might further enhance the antitumorigenic effects of these molecules in colon cancer cells.

Beta-Catenin stabilizes cyclooxygenase-2 mRNA by interacting with AU-rich elements of 3'-UTR.

Cyclooxygenase-2 (COX-2) mRNA is induced in the majority of human colorectal carcinomas. Transcriptional regulation plays a key role in COX-2 expression in human colon carcinoma cells, but post-transcriptional regulation of its mRNA is also critical for tumorigenesis. Expression of COX-2 mRNA is regulated by various cytokines, growth factors and other signals. beta-Catenin, a key transcription factor in the Wnt signal pathway, activates transcription of COX-2. Here we found that COX-2 mRNA was also substantially stabilized by activating beta-catenin in NIH3T3 and 293T cells. We identified the beta-catenin-responsive element in the proximal region of the COX-2 3'-untranslated region (3'-UTR) and showed that beta-catenin interacted with AU-rich elements (ARE) of 3'-UTR in vitro and in vivo. Interestingly, beta-catenin induced the cytoplasmic localization of the RNA stabilizing factor, HuR, which may bind to beta-catenin in an RNA-mediated complex and facilitate beta-catenin-dependent stabilization of COX-2 mRNA. Taken together, we provided evidences for beta-catenin as an RNA-binding factor and a regulator of stabilization of COX-2 mRNA.

Modulation of oncogenic transcription and alternative splicing by beta-catenin and an RNA aptamer in colon cancer cells.

Activated beta-catenin regulates the transcription of oncogenic target genes and is critical for tumorigenesis. Because nuclear functions are frequently coupled, we investigated whether it also has a role in alternative splicing of oncogenic genes. We showed that stabilized beta-catenin caused alternative splicing of estrogen receptor-beta pre-mRNA in colon cancer cells. To establish a direct role of beta-catenin in regulated splicing, we selected a high-affinity RNA aptamer that associated with beta-catenin in vivo. Nuclear localized aptamer inhibited beta-catenin-dependent transcription of cyclin D1 and c-myc in colon cancer cells; thus, cells stably expressing the aptamer exhibited cell cycle arrest and reduced tumor forming potential. Most significantly, the aptamer prevented the alternative splicing induced by stabilized beta-catenin. Taken together, our results establish that beta-catenin has an important role in both transcription and splicing, and that its action can be modulated by a high-affinity RNA aptamer. The RNA aptamer could be further developed as a specific inhibitor for cancer therapeutics.

Intracellular expression of the T-cell factor-1 RNA aptamer as an intramer.

T-cell factor (TCF)-1 protein forms the transcriptional complex with beta-catenin and regulates the expression of diverse target genes during early development and carcinogenesis. We have selected previously an RNA aptamer that binds to the DNA-binding domain of TCF-1 and have shown that it interfered with binding of TCF-1 to its specific DNA recognition sequences in vitro. As an approach to modulate the transcription by TCF/beta-catenin complex in the cells, we have developed the RNA expression vector for stable expression of RNA aptamer inside of the mammalian cells. High level of RNA was expressed as an intramer in the fusion with the stable RNA transcript. The RNA intramer inhibited TCF/beta-catenin transcription activity as shown by luciferase assay. It also modulated the expression of TCF/beta-catenin target genes, such as cyclin D1 and matrix metalloproteinase-7, as predicted to be as an effective inhibitor of the TCF function. In addition, it efficiently reduced the growth rate and tumorigenic potential of HCT116 colon cancer cells. Such RNA intramer could lead to valuable gene therapeutics for TCF/beta-catenin-mediated carcinogenesis.

Adiponectin represses colon cancer cell proliferation via AdipoR1- and -R2-mediated AMPK activation.

In obesity, dysregulation of adipocytokines is involved in several pathological conditions including diabetes and certain cancers. As a member of the adipocytokines, adiponectin plays crucial roles in whole-body energy homeostasis. Recently, it has been reported that the level of plasma adiponectin is reduced in several types of cancer patients. However, it is largely unknown whether and how adiponectin affects colon cancer cell growth. Here, we show that adiponectin suppresses the proliferation of colon cancer cells including HCT116, HT29, and LoVo. In colon cancer cells, adiponectin attenuated cell cycle progression at the G(1)/S boundary and concurrently increased expression of cyclin-dependent kinase inhibitors such as p21 and p27. Adiponectin stimulated AMP-activated protein kinase (AMPK) phosphorylation whereas inhibition of AMPK activity blunted the effect of adiponectin on the proliferation of colon cancer cells. Furthermore, knockdown of adiponectin receptors such as AdipoR1 and AdipoR2 relieved the suppressive effect of adiponectin on the growth of colon cancer cells. In addition, adiponectin repressed the expression of sterol regulatory element binding protein-1c, which is a key lipogenic transcription factor associated with colon cancers. These results suggest that adiponectin could inhibit the growth of colon cancer cells through stimulating AMPK activity.

The RNA aptamer disrupts protein-protein interaction between beta-catenin and nuclear factor-kappaB p50 and regulates the expression of C-reactive protein.

Transcription is activated by signal-induced protein-protein interaction between transcription factors on regulatory elements positioned near their target genes. Here, we tested the utility of the beta-catenin binding RNA aptamer as a tool for studying protein-protein interaction within transcription complex and for modulating expression of a target gene. The RNA aptamer bound Armadillo repeats of beta-catenin and was effective in disrupting protein-protein interaction between beta-catenin and nuclear factor-kappaB (NF-kappaB) p50. In addition, the RNA aptamer effectively reduced tumor necrosis factor-alpha induced transcription from the promoter of C-reactive protein regulated by beta-catenin and NF-kappaB p50. Taken together, beta-catenin binding RNA aptamer was an effective regulator of beta-catenin and NF-kappaB p50 mediated transcription.