Showing papers in "Signal Transduction and Targeted Therapy in 2018"

Controlled drug delivery vehicles for cancer treatment and their performance.

Abstract: Although conventional chemotherapy has been successful to some extent, the main drawbacks of chemotherapy are its poor bioavailability, high-dose requirements, adverse side effects, low therapeutic indices, development of multiple drug resistance, and non-specific targeting. The main aim in the development of drug delivery vehicles is to successfully address these delivery-related problems and carry drugs to the desired sites of therapeutic action while reducing adverse side effects. In this review, we will discuss the different types of materials used as delivery vehicles for chemotherapeutic agents and their structural characteristics that improve the therapeutic efficacy of their drugs and will describe recent scientific advances in the area of chemotherapy, emphasizing challenges in cancer treatments.

Targeting oncogenic Myc as a strategy for cancer treatment

Abstract: The MYC family oncogene is deregulated in >50% of human cancers, and this deregulation is frequently associated with poor prognosis and unfavorable patient survival. Myc has a central role in almost every aspect of the oncogenic process, orchestrating proliferation, apoptosis, differentiation, and metabolism. Although Myc inhibition would be a powerful approach for the treatment of many types of cancers, direct targeting of Myc has been a challenge for decades owing to its "undruggable" protein structure. Hence, alternatives to Myc blockade have been widely explored to achieve desirable anti-tumor effects, including Myc/Max complex disruption, MYC transcription and/or translation inhibition, and Myc destabilization as well as the synthetic lethality associated with Myc overexpression. In this review, we summarize the latest advances in targeting oncogenic Myc, particularly for cancer therapeutic purposes.

The independence of and associations among apoptosis, autophagy, and necrosis.

Abstract: Cell death is an essential biological process for physiological growth and development. Three classical forms of cell death-apoptosis, autophagy, and necrosis-display distinct morphological features by activating specific signaling pathways. With recent research advances, we have started to appreciate that these cell death processes can cross-talk through interconnecting, even overlapping, signaling pathways, and the final cell fate is the result of the interplay of different cell death programs. This review provides an insight into the independence of and associations among these three types of cell death and explores the significance of cell death under the specific conditions of human diseases, particularly neurodegenerative diseases and cancer.

The intracellular signalosome of PD-L1 in cancer cells.

Abstract: Programmed cell death-1 ligand-1 (PD-L1) overexpression in cancer cells accelerates tumor progression PD-L1 possesses two main pro-oncogenic functions First, PD-L1 is a strong immunosuppressive molecule that inactivates tumor-specific T cells by binding to the inhibitory receptor PD-1 Second, PD-L1 function relies on the delivery of intrinsic intracellular signals that enhance cancer cell survival, regulate stress responses and confer resistance toward pro-apoptotic stimuli, such as interferons Here, we review the current knowledge on intracellular signal transduction pathways regulated by PD-L1, describe its associated signalosome and discuss potential combinations of targeted therapies against the signalosome with PD-L1/PD-1 blockade therapies Programmed cell death-1 ligand-1 (PD-L1) favors tumor progression by suppressing the immune system and regulating pro-survival signaling pathways in cancer cells Therapeutic antibodies that block the interaction between PD-L1 expressed in cancer cells and the PD-1 receptor on T cells are showing great promise for treating many human cancers However, remarkably little is known about the effects of PD-L1 in cancer cells themselves Grazyna Kochan at the Instituto de Investigacion Sanitaria de Navarra, Spain, and colleagues review current knowledge on PD-L1 expression and function in cancer cells PD-L1 can enhance cancer cell survival by regulating glucose metabolism and conferring resistance to pro-apoptotic stimuli, such as interferons, without engaging PD-1 Further understanding of the intracellular signaling pathways that are regulated by PD-L1 could inform on therapeutic combinations that could enhance the efficacy of anti-PD-L1/anti-PD-1 antibodies

Yes-associated protein (YAP) in pancreatic cancer: at the epicenter of a targetable signaling network associated with patient survival

Abstract: Pancreatic ductal adenocarcinoma (PDAC) is generally a fatal disease with no efficacious treatment modalities. Elucidation of signaling mechanisms that will lead to the identification of novel targets for therapy and chemoprevention is urgently needed. Here, we review the role of Yes-associated protein (YAP) and WW-domain-containing Transcriptional co-Activator with a PDZ-binding motif (TAZ) in the development of PDAC. These oncogenic proteins are at the center of a signaling network that involves multiple upstream signals and downstream YAP-regulated genes. We also discuss the clinical significance of the YAP signaling network in PDAC using a recently published interactive open-access database (www.proteinatlas.org/pathology) that allows genome-wide exploration of the impact of individual proteins on survival outcomes. Multiple YAP/TEAD-regulated genes, including AJUBA, ANLN, AREG, ARHGAP29, AURKA, BUB1, CCND1, CDK6, CXCL5, EDN2, DKK1, FOSL1,FOXM1, HBEGF, IGFBP2, JAG1, NOTCH2, RHAMM, RRM2, SERP1, and ZWILCH, are associated with unfavorable survival of PDAC patients. Similarly, components of AP-1 that synergize with YAP (FOSL1), growth factors (TGFα, EPEG, and HBEGF), a specific integrin (ITGA2), heptahelical receptors (P2Y2R, GPR87) and an inhibitor of the Hippo pathway (MUC1), all of which stimulate YAP activity, are associated with unfavorable survival of PDAC patients. By contrast, YAP inhibitory pathways (STRAD/LKB-1/AMPK, PKA/LATS, and TSC/mTORC1) indicate a favorable prognosis. These associations emphasize that the YAP signaling network correlates with poor survival of pancreatic cancer patients. We conclude that the YAP pathway is a major determinant of clinical aggressiveness in PDAC patients and a target for therapeutic and preventive strategies in this disease.

Metabolite sensing and signaling in cell metabolism

Abstract: Metabolite sensing is one of the most fundamental biological processes. During evolution, multilayered mechanisms developed to sense fluctuations in a wide spectrum of metabolites, including nutrients, to coordinate cellular metabolism and biological networks. To date, AMPK and mTOR signaling are among the best-understood metabolite-sensing and signaling pathways. Here, we propose a sensor-transducer-effector model to describe known mechanisms of metabolite sensing and signaling. We define a metabolite sensor by its specificity, dynamicity, and functionality. We group the actions of metabolite sensing into three different modes: metabolite sensor-mediated signaling, metabolite-sensing module, and sensing by conjugating. With these modes of action, we provide a systematic view of how cells sense sugars, lipids, amino acids, and metabolic intermediates. In the future perspective, we suggest a systematic screen of metabolite-sensing macromolecules, high-throughput discovery of biomacromolecule-metabolite interactomes, and functional metabolomics to advance our knowledge of metabolite sensing and signaling. Most importantly, targeting metabolite sensing holds great promise in therapeutic intervention of metabolic diseases and in improving healthy aging.

Targeting IL-2: an unexpected effect in treating immunological diseases.

Abstract: Regulatory T cells (Treg) play a crucial role in maintaining immune homeostasis since Treg dysfunction in both animals and humans is associated with multi-organ autoimmune and inflammatory disease. While IL-2 is generally considered to promote T-cell proliferation and enhance effector T-cell function, recent studies have demonstrated that treatments that utilize low-dose IL-2 unexpectedly induce immune tolerance and promote Treg development resulting in the suppression of unwanted immune responses and eventually leading to treatment of some autoimmune disorders. In the present review, we discuss the biology of IL-2 and its signaling to help define the key role played by IL-2 in the development and function of Treg cells. We also summarize proof-of-concept clinical trials which have shown that low-dose IL-2 can control autoimmune diseases safely and effectively by specifically expanding and activating Treg. However, future studies will be needed to validate a better and safer dosing strategy for low-dose IL-2 treatments utilizing well-controlled clinical trials. More studies will also be needed to validate the appropriate dose of IL-2/anti-cytokine or IL-2/anti-IL-2 complex in the experimental animal models before moving to the clinic.

DNA methylation profile is associated with the osteogenic potential of three distinct human odontogenic stem cells.

Abstract: Among the various sources of human autologous stem cells, stem cells isolated from dental tissues exhibit excellent properties in tissue engineering and regenerative medicine. However, the distinct potential of these odontogenic cell lines remains unclear. In this study, we analyzed DNA methylation patterns to determine whether specific differences existed among three different odontogenic cell types. Using the HumanMethylation450 Beadchip, the whole genomes of human dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), and dental follicle progenitor cells (DFPCs) were compared. Then, the osteogenic potential of these cells was evaluated both in vitro and in vivo, and the methylation levels of certain genes related to bone formation differed among the three cell lines. P values less than 0.05 were considered to indicate statistical significance. The three cell types showed highly similar DNA methylation patterns, although specific differences were identified. Gene ontology analysis revealed that one of the most significantly different gene categories was related to bone formation. Thus, expression of cell surface epitopes and osteogenic-related transcription factors as well as the bone formation capacity were compared. The results showed that compared with DFPCs and DPSCs, PDLSCs had higher transcription levels of osteogenic-related factors, a higher in vitro osteogenic potential, and an increased new bone formation capacity in vivo. In conclusion, the results of this study suggested that the differential DNA methylation profiles could be related to the osteogenic potential of these human odontogenic cell populations. Additionally, the increased osteogenic potential of PDLSCs might aid researchers or clinicians in making better choices regarding tissue regeneration and clinical therapies.

Emerging insights into HAUSP (USP7) in physiology, cancer and other diseases

Abstract: Herpesvirus-associated ubiquitin-specific protease (HAUSP) is a USP family deubiquitinase. HAUSP is a protein of immense biological importance as it is involved in several cellular processes, including host-virus interactions, oncogenesis and tumor suppression, DNA damage and repair processes, DNA dynamics and epigenetic modulations, regulation of gene expression and protein function, spatio-temporal distribution, and immune functions. Since its discovery in the late 1990s as a protein interacting with a herpes virus regulatory protein, extensive studies have assessed its complex roles in p53-MDM2-related networks, identified numerous additional interacting partners, and elucidated the different roles of HAUSP in the context of cancer, development, and metabolic and neurological pathologies. Recent analyses have provided new insights into its biochemical and functional dynamics. In this review, we provide a comprehensive account of our current knowledge about emerging insights into HAUSP in physiology and diseases, which shed light on fundamental biological questions and promise to provide a potential target for therapeutic intervention.

miRNAs reshape immunity and inflammatory responses in bacterial infection.

Abstract: Pathogenic bacteria cause various infections worldwide, especially in immunocompromised and other susceptible individuals, and are also associated with high infant mortality rates in developing countries. MicroRNAs (miRNAs), small non-coding RNAs with evolutionarily conserved sequences, are expressed in various tissues and cells that play key part in various physiological and pathologic processes. Increasing evidence implies roles for miRNAs in bacterial infectious diseases by modulating inflammatory responses, cell penetration, tissue remodeling, and innate and adaptive immunity. This review highlights some recent intriguing findings, ranging from the correlation between aberrant expression of miRNAs with bacterial infection progression to their profound impact on host immune responses. Harnessing of dysregulated miRNAs in bacterial infection may be an approach to improving the diagnosis, prevention and therapy of infectious diseases. Changes in production of tiny cellular RNAs in response to bacterial infection could guide the development of better diagnostics and therapies. MicroRNAs regulate other genes by binding to messenger RNA strands and controlling their translation into proteins. Xikun Zhou, Min Wu and colleagues of the University of North Dakota have now reviewed current knowledge about how microRNA levels shift during infection with various bacterial pathogens. These microRNAs can modulate the immune response as well as pathways that influence metabolic activity and cell survival. Increasing studies have indicated that shifts in microRNA levels in response to different infections could provide a potential bacterial ‘fingerprint’ for achieving accurate diagnosis. With deeper insight into how different microRNAs influence infection, it might one day day become possible to target these molecules with ‘antisense’ or ‘agonist’ drugs that modulate their activity.

Increased mtDNA copy number promotes cancer progression by enhancing mitochondrial oxidative phosphorylation in microsatellite-stable colorectal cancer.

Abstract: Colorectal cancer is one of the leading causes of cancer death worldwide. According to global genomic status, colorectal cancer can be classified into two main types: microsatellite-stable and microsatellite-instable tumors. Moreover, the two subtypes also exhibit different responses to chemotherapeutic agents through distinctive molecular mechanisms. Recently, mitochondrial DNA depletion has been shown to induce apoptotic resistance in microsatellite-instable colorectal cancer. However, the effects of altered mitochondrial DNA copy number on the progression of microsatellite-stable colorectal cancer, which accounts for the majority of colorectal cancer, remain unclear. In this study, we systematically investigated the functional role of altered mitochondrial DNA copy number in the survival and metastasis of microsatellite-stable colorectal cancer cells. Moreover, the underlying molecular mechanisms were also explored. Our results demonstrated that increased mitochondrial DNA copy number by forced mitochondrial transcription factor A expression significantly facilitated cell proliferation and inhibited apoptosis of microsatellite-stable colorectal cancer cells both in vitro and in vivo. Moreover, we demonstrated that increased mitochondrial DNA copy number enhanced the metastasis of microsatellite-stable colorectal cancer cells. Mechanistically, the survival advantage conferred by increased mitochondrial DNA copy number was caused in large part by elevated mitochondrial oxidative phosphorylation. Furthermore, treatment with oligomycin significantly suppressed the survival and metastasis of microsatellite-stable colorectal cancer cells with increased mitochondrial DNA copy number. Our study provides evidence supporting a possible tumor-promoting role for mitochondrial DNA and uncovers the underlying mechanism, which suggests a potential novel therapeutic target for microsatellite-stable colorectal cancer.

A nanomedicine approach enables co-delivery of cyclosporin A and gefitinib to potentiate the therapeutic efficacy in drug-resistant lung cancer

Abstract: Drug resistance, accounting for therapeutic failure in the clinic, remains a major challenge to effectively manage cancer. Cyclosporin A (CsA) can reverse multidrug resistance (MDR), especially resistance to epidermal growth factor receptor tyrosine kinase inhibitors. However, the application of both drugs in cancer therapies is hampered by their poor aqueous solubility and low bioavailability due to oral administration. CsA augments the potency of gefitinib (Gef) in both Gef-sensitive and Gef-resistant cell lines. Here, we show that the simultaneous encapsulation of CsA and Gef within polyethylene glycol-block-poly(D, L-lactic acid) (PEG-PLA) produced a stable and systemically injectable nanomedicine, which exhibited a sub-50-nm diameter and spherical structures. Impressively, the co-delivery of therapeutics via single nanoparticles (NPs) outperformed the oral administration of the free drug combination at suppressing tumor growth. Furthermore, in vivo results indicated that CsA formulated in NPs sensitized Gef-resistant cells and Gef-resistant tumors to Gef treatment by inactivating the STAT3/Bcl-2 signaling pathway. Collectively, our nanomedicine approach not only provides an alternative administration route for the drugs of choice but also effectively reverses MDR, facilitating the development of effective therapeutic modalities for cancer.

Transcriptional cofactors Ski and SnoN are major regulators of the TGF-β/Smad signaling pathway in health and disease.

Abstract: The transforming growth factor-β (TGF-β) family plays major pleiotropic roles by regulating many physiological processes in development and tissue homeostasis. The TGF-β signaling pathway outcome relies on the control of the spatial and temporal expression of >500 genes, which depend on the functions of the Smad protein along with those of diverse modulators of this signaling pathway, such as transcriptional factors and cofactors. Ski (Sloan-Kettering Institute) and SnoN (Ski novel) are Smad-interacting proteins that negatively regulate the TGF-β signaling pathway by disrupting the formation of R-Smad/Smad4 complexes, as well as by inhibiting Smad association with the p300/CBP coactivators. The Ski and SnoN transcriptional cofactors recruit diverse corepressors and histone deacetylases to repress gene transcription. The TGF-β/Smad pathway and coregulators Ski and SnoN clearly regulate each other through several positive and negative feedback mechanisms. Thus, these cross-regulatory processes finely modify the TGF-β signaling outcome as they control the magnitude and duration of the TGF-β signals. As a result, any alteration in these regulatory mechanisms may lead to disease development. Therefore, the design of targeted therapies to exert tight control of the levels of negative modulators of the TGF-β pathway, such as Ski and SnoN, is critical to restore cell homeostasis under the specific pathological conditions in which these cofactors are deregulated, such as fibrosis and cancer.

Biological processes and signal transduction pathways regulated by the protein methyltransferase SETD7 and their significance in cancer

Abstract: Protein methyltransferases have been shown to methylate histone and non-histone proteins, leading to regulation of several biological processes that control cell homeostasis. Over the past few years, the histone-lysine N-methyltransferase SETD7 (SETD7; also known as SET7/9, KIAA1717, KMT7, SET7, SET9) has emerged as an important regulator of at least 30 non-histone proteins and a potential target for the treatment of several human diseases. This review discusses current knowledge of the structure and subcellular localization of SETD7, as well as its function as a histone and non-histone methyltransferase. This work also underlines the putative contribution of SETD7 to the regulation of gene expression, control of cell proliferation, differentiation and endoplasmic reticulum stress, which indicate that SETD7 is a candidate for novel targeted therapies with the aim of either stimulating or inhibiting its activity, depending on the cell signaling context.

The role of autophagy in colitis-associated colorectal cancer

Abstract: Autophagy is an evolutionarily conserved catabolic process that eliminates harmful components through lysosomal degradation. In addition to its role in maintaining cellular homeostasis, autophagy is critical to pathological processes, such as inflammation and cancer. Colitis-associated colorectal cancer (CAC) is a specific type of colorectal cancer that develops from long-standing colitis in inflammatory bowel disease (IBD) patients. Accumulating evidence indicates that autophagy of microenvironmental cells plays different but vital roles during tumorigenesis and CAC development. Herein, after summarizing the recent advances in understanding the role of autophagy in regulating the tumor microenvironment during different CAC stages, we draw the following conclusions: autophagy in intestinal epithelial cells inhibits colitis and CAC initiation but promotes CAC progression; autophagy in macrophages inhibits colitis, but its function on CAC is currently unclear; autophagy in neutrophils and cancer-associated fibroblasts (CAFs) promotes both colitis and CAC; autophagy in dendritic cells (DCs) and T cells represses both colitis and CAC; autophagy in natural killer cells (NKs) inhibits colitis, but promotes CAC; and autophagy in endothelial cells plays a controversial role in colitis and CAC. Understanding the role of autophagy in specific compartments of the tumor microenvironment during different stages of CAC may provide insight into malignant transformation, tumor progression, and combination therapy strategies for CAC.

miR-23a promotes invasion of glioblastoma via HOXD10-regulated glial-mesenchymal transition.

Abstract: Glioblastoma is the most aggressive and invasive brain tumor and has a poor prognosis; elucidating the underlying molecular mechanisms is essential to select molecular targeted therapies. Here, we investigated the effect of microRNAs on the marked invasiveness of glioblastoma. U373 glioblastoma cells were infected with 140 different microRNAs from an OncomiR library, and the effects of the invasion-related microRNAs and targeted molecules were investigated after repeated Matrigel invasion assays. Screening of the OncomiR library identified miR-23a as a key regulator of glioblastoma invasion. In six glioblastoma cell lines, a positive correlation was detected between the expression levels of miR-23a and invasiveness. A luciferase reporter assay demonstrated that homeobox D10 (HOXD10) was a miR-23a-target molecule, which was verified by high scores from both the PicTar and miRanda algorithms. Forced expression of miR-23a induced expression of invasion-related molecules, including uPAR, RhoA, and RhoC, and altered expression of glial-mesenchymal transition markers such as Snail, Slug, MMP2, MMP9, MMP14, and E-cadherin; however, these changes in expression levels were reversed by HOXD10 overexpression. Thus, miR-23a significantly promoted invasion of glioblastoma cells with polarized formation of focal adhesions, while exogenous HOXD10 overexpression reversed these phenomena. Here, we identify miR-23a-regulated HOXD10 as a pivotal regulator of invasion in glioblastoma, providing a novel mechanism for the aggressive invasiveness of this tumor and providing insight into potential therapeutic targets. Researchers in Japan have identified key genetic players in an aggressive form of brain cancer. Glioblastoma is the most invasive type of brain tumor, with a five-year survival rate of just 7%. To investigate its invasiveness, a team led by Shinya Tanaka of Hokkaido University tested the effect of 140 microRNAs on glioblastoma cells. They found that miR-23a increased the invasiveness of the cells. Further research revealed that miR-23a reduces the level of the regulatory gene HOXD10 by destroying the protein it encodes. This reduction leads to changes in the expression of genes regulated by HOXD10, increasing affected cells’ invasiveness and altering their morphology. The miR-23a/HOXD10 pathway revealed here not only provides insight into the biology of glioblastoma but also offers a potential therapeutic target.

RNA-binding protein LIN28B inhibits apoptosis through regulation of the AKT2/FOXO3A/BIM axis in ovarian cancer cells.

Abstract: LIN28B is an evolutionarily conserved RNA-binding protein that regulates mRNA translation and miRNA let-7 maturation in embryonic stem cells and developing tissues. Increasing evidence demonstrates that LIN28B is activated in cancer and serves as a critical oncogene. However, the underlying molecular mechanisms of LIN28B function in tumorigenesis are still largely unknown. Here we report that LIN28B was expressed in over half of the patients with epithelial ovarian cancer who were examined (n = 584). Functional experiments demonstrated that LIN28B inhibited ovarian cancer cell apoptosis. Furthermore, we showed that the proapoptotic factor BIM played an essential role in the antiapoptotic function of LIN28B. RNA-IP microarray analysis suggested that LIN28B binds to mRNAs that are associated with the DNA damage pathway, such as AKT2, in ovarian cancer cells. By binding to AKT2 mRNA and enhancing its protein expression, LIN28B regulated FOXO3A protein phosphorylation and decreased the transcriptional level of BIM, which antagonized the antiapoptosis activity of LIN28B. Taken together, these results mechanistically linked LIN28B and the AKT2/FOXO3A/BIM axis to the apoptosis pathway. The findings may have important implications in the diagnosis and therapeutics of ovarian cancer. Researchers in China have uncovered the molecular mechanism behind the activity of a gene related to ovarian cancer. Xiaomin Zhong’s team at Sun Yat-Sen University knocked down the gene, LIN28B, in cancer cell lines and discovered that this increased their response to a chemical, which induces programmed cell death (PCD). By contrast, increasing LIN28B expression reduced PCD sensitivity, leading to the conclusion that LIN28B inhibits PCD in cancer cells. Examining gene expression in the knockdown lines revealed that LIN28B suppresses the activity of the PCD-related gene BIM. Further experiments showed that this happens through the modulation of genes upstream of BIM. These results demonstrate that LIN28B acts by regulating a genetic pathway, which regulates PCD. Altogether, this improved understanding of LIN28B may help with the diagnosis and therapy of ovarian cancer.

Targeted chemotherapy for subcutaneous and orthotopic non-small cell lung tumors with cyclic RGD-functionalized and disulfide-crosslinked polymersomal doxorubicin

Abstract: Lung cancer, with its high mortality and increasing morbidity, has become one of the most lethal malignancies worldwide. Here, we developed cyclic RGD peptide-directed and disulfide-crosslinked polymersomal doxorubicin (cRGD-PS-Dox) as a targeted chemotherapy for human non-small cell lung cancer (NSCLC). Notably, cRGD-PS-Dox exhibited a high Dox loading (15.2 wt.%), small hydrodynamic diameter (96 nm), superb stability, prominent targetability to αvβ3 integrin overexpressing A549 human lung cancer cells, and rapid release of the drug into nuclei, leading to a significantly improved antitumor activity compared with the control groups, i.e., PS-Dox and Lipo-Dox (a liposome injection employed in clinical settings). The pharmacokinetic and biodistribution results for cRGD-PS-Dox revealed similar elimination half-lives but two-fold enhanced tumor accumulation compared with PS-Dox and Lipo-Dox. Intriguingly, cRGD-PS-Dox effectively suppressed the growth of A549 lung tumors in both subcutaneous and orthotopic models with minimal adverse effects at a Dox dose of 12 mg/kg, leading to significant survival benefits compared with PS-Dox and Lipo-Dox. This αvβ3 integrin-targeting multifunctional polymersomal doxorubicin is highly promising for targeted chemotherapy of human NSCLC. When wrapped in an engineered vesicle and augmented with cancer-targeting peptides, chemotherapy drug doxorubicin shows increased efficacy in a preclinical study. Zhiyuan Zhong, from China’s Soochow University, and his team developed the therapeutic (cRGD-PS-Dox) that targets cancer cells that overexpress a specific protein (αvβ3 integrin), such as those of non-small cell lung cancer. In vitro assays showed that cRGD-PS-Dox specifically targeted and inhibited cancer cells, and inhibited the growth and metastasis of human tumor grafts in mice. In vivo imaging confirmed a desirable drug stability profile and accumulation within tumors. These results showed clear advantages over non-targeted doxorubicin treatment controls. Mice treated with cRGD-PS-Dox also survived significantly longer than control-treated mice. The preferential attributes of the therapy make it a promising agent for further study into tumors that overexpress αvβ3 integrin.

USP7 deubiquitinates and stabilizes NOTCH1 in T-cell acute lymphoblastic leukemia

Abstract: T-cell acute lymphoblastic leukemia (T-ALL) is a highly aggressive leukemia that is primarily caused by aberrant activation of the NOTCH1 signaling pathway. Recent studies have revealed that posttranslational modifications, such as ubiquitination, regulate NOTCH1 stability, activity, and localization. However, the specific deubiquitinase that affects NOTCH1 protein stability remains unestablished. Here, we report that ubiquitin-specific protease 7 (USP7) can stabilize NOTCH1. USP7 deubiquitinated NOTCH1 in vivo and in vitro, whereas knockdown of USP7 increased the ubiquitination of NOTCH1. USP7 interacted with NOTCH1 protein in T-ALL cells, and the MATH and UBL domains of USP7 were responsible for this interaction. Depletion of USP7 significantly suppressed the proliferation of T-ALL cells in vitro and in vivo, accompanied by downregulation of the NOTCH1 protein level. Similarly, pharmacologic inhibition of USP7 led to apoptosis of T-ALL cells. More importantly, we found that USP7 was significantly upregulated in human T-ALL cell lines and patient samples, and a USP7 inhibitor exhibited cell cytotoxicity toward primary T-ALL cells, indicating the clinical relevance of these findings. Overall, our results demonstrate that USP7 is a novel deubiquitinase that stabilizes NOTCH1. Therefore, USP7 may be a promising therapeutic target in the currently incurable T-ALL.

γ-tubulin as a signal-transducing molecule and meshwork with therapeutic potential.

Abstract: Knowledge of γ-tubulin is increasing with regard to the cellular functions of this protein beyond its participation in microtubule nucleation γ-Tubulin expression is altered in various malignancies, and changes in the TUBG1 gene have been found in patients suffering from brain malformations This review recapitulates the known functions of γ-tubulin in cellular homeostasis and discusses the possible influence of the protein on disease development and cancer

Targeting MUC1-C suppresses BCL2A1 in triple-negative breast cancer

Abstract: B-cell lymphoma 2-related protein A1 (BCL2A1) is a member of the BCL-2 family of anti-apoptotic proteins that confers resistance to treatment with anti-cancer drugs; however, there are presently no agents that target BCL2A1. The MUC1-C oncoprotein is aberrantly expressed in triple-negative breast cancer (TNBC) cells, induces the epithelial-mesenchymal transition (EMT) and promotes anti-cancer drug resistance. The present study demonstrates that targeting MUC1-C genetically and pharmacologically in TNBC cells results in the downregulation of BCL2A1 expression. The results show that MUC1-C activates the BCL2A1 gene by an NF-κB p65-mediated mechanism, linking this pathway with the induction of EMT. The MCL-1 anti-apoptotic protein is also of importance for the survival of TNBC cells and is an attractive target for drug development. We found that inhibiting MCL-1 with the highly specific MS1 peptide results in the activation of the MUC1-C→NF-κB→BCL2A1 pathway. In addition, selection of TNBC cells for resistance to ABT-737, which inhibits BCL-2, BCL-xL and BCL-W but not MCL-1 or BCL2A1, is associated with the upregulation of MUC1-C and BCL2A1 expression. Targeting MUC1-C in ABT-737-resistant TNBC cells suppresses BCL2A1 and induces death, which is of potential therapeutic importance. These findings indicate that MUC1-C is a target for the treatment of TNBCs unresponsive to agents that inhibit anti-apoptotic members of the BCL-2 family.

ETV2 mediates endothelial transdifferentiation of glioblastoma

Abstract: Glioblastoma multiforme (GBM) is characterized by extensive endothelial hyperplasia. Recent studies suggest that a subpopulation of endothelial cells originates via vasculogenesis by the transdifferentiation of GBM tumor cells into endothelial cells (endo-transdifferentiation). The molecular mechanism underlying this process remains poorly defined. Here, we show that the expression of ETS variant 2 (ETV2), a master regulator of endothelial cell development, is highly correlated with malignancy. Functional studies demonstrate that ETV2 is sufficient and necessary for the transdifferentiation of a subpopulation of CD133+/Nestin+ GBM/neural stem cells to an endothelial lineage. Combinational studies of ChIP-Seq with gain-of-function RNA-Seq data sets suggest that ETV2, in addition to activating vascular genes, represses proneural genes to direct endo-transdifferentiation. Since endo-transdifferentiation by ETV2 is VEGF-A independent, it likely accounts for the observed resistance of GBM tumor cells to anti-angiogenesis therapy. Further characterization of the regulatory networks mediated by ETV2 in endo-transdifferentiation of GBM tumor cells should lead to the identification of more effective therapeutic targets for GBM.

Loss of mdig expression enhances DNA and histone methylation and metastasis of aggressive breast cancer.

Abstract: We previously reported that expression of an environmentally induced gene, mineral dust-induced gene (mdig), predicts overall survival in breast cancer patients In the present report, we further demonstrate the differential roles of mdig between earlier- and later-stage breast cancers In noncancerous breast, mdig is a proliferation factor for cell growth and cell motility In breast cancer, however, higher levels of mdig negatively regulate the migration and invasion of cancer cells Assessment of global DNA methylation, chromatin accessibility and H3K9me3 heterochromatin signature suggests that silencing mdig enhances DNA and histone methylation Through immunostaining and data mining, we found that mdig is significantly upregulated in noninvasive and/or earlier-stage breast cancers In contrast, in triple-negative and other invasive breast cancers, diminished mdig expression was noted, indicating that the loss of mdig expression could be an important feature of aggressive breast cancers Taken together, our data suggest that mdig is a new biomarker that likely promotes tumor growth in the early stages of breast cancer while acting as a tumor suppressor to inhibit invasion and metastasis in later-stage tumors

Pan-CDK inhibition augments cisplatin lethality in nasopharyngeal carcinoma cell lines and xenograft models.

Abstract: In addition to their canonical roles in regulating cell cycle transition and transcription, cyclin-dependent kinases (CDKs) have been shown to coordinate DNA damage response pathways, suggesting a rational pairing of CDK inhibitors with genotoxic chemotherapeutic agents in the treatment of human malignancies. Here, we report that roniciclib (BAY1000394), a potent pan-CDK inhibitor, displays promising anti-neoplastic activity as a single agent and potentiates cisplatin lethality in preclinical nasopharyngeal carcinoma (NPC) models. Proliferation of the NPC cell lines HONE-1, CNE-2, C666-1, and HK-1 was effectively curbed by roniciclib treatment, with IC50 values between 11 and 38 nmol/L. These anticancer effects were mediated by pleiotropic mechanisms consistent with successful blockade of cell cycle CDKs 1, 2, 3, and 4 and transcriptional CDKs 7 and 9, ultimately resulting in arrest at G1/S and G2/M, downregulation of the transcriptional apparatus, and repression of anti-apoptotic proteins. Considerably enhanced tumor cell apoptosis was achieved following combined treatment with 10 nmol/L roniciclib and 2.0 μmol/L cisplatin; this combination therapy achieved a response over 250% greater than either drug alone. Although roniciclib chemosensitized NPC cells to cisplatin, it did not sensitize untransformed (NP69) cells. The administration of 0.5 mg/kg roniciclib to BALB/c xenograft mice was well tolerated and effectively restrained tumor growth comparable to treatment with 6 mg/kg cisplatin, whereas combining these two agents produced far greater tumor suppression than either of the monotherapies. In summary, these data demonstrate that roniciclib has strong anti-NPC activity and synergizes with cisplatin chemotherapy at clinically relevant doses, thus justifying further evaluation of this combinatorial approach in clinical settings. Nasopharyngeal carcinoma (NPC) is an uncommon malignancy arising from the nasopharynx epithelium, and is endemic to east and southeast parts of Asia where they account for 70% of worldwide incidence. Researchers from the Cancer Science Institute of Singapore examined the anti-tumor effects of roniciclib—a small-molecule drug that blocks a family of enzymes known as cyclin-dependent kinases (CDKs) which are classically involved in cell cycle progression and transcription—in cell lines and mouse models of nasopharyngeal carcinoma. Because CDK/cyclin complexes have a putative role in DNA repair, roniciclib was combined with cisplatin, a DNA-damaging agent which is currently used in chemotherapy of NPC. The authors found that roniciclib had potent anti-NPC effects when given alone, whereas the combination of roniciclib and cisplatin proved to be highly synergistic and restrained tumor growth to a greater extent than either drugs given alone. Interestingly, roniciclib appeared to selectively enhance the anti-cancer effects of cisplatin in cancerous cells while this “chemo-sensitizing” phenomenon was not seen in non-cancerous cells, suggesting that giving both drugs together could improve the effectiveness of standard chemotherapy without incurring additional toxicities. These findings suggest that roniciclib should be evaluated clinically in patients with NPC.

Novel HDAC5-interacting motifs of Tbx3 are essential for the suppression of E-cadherin expression and for the promotion of metastasis in hepatocellular carcinoma.

Abstract: Tbx3, a transcriptional repressor, is essential in the organogenesis of vertebrates, stem cell self-renewal and differentiation, and the carcinogenesis of multiple tumor types. However, the mechanism by which Tbx3 participates in the metastasis of hepatocellular carcinoma (HCC) remains largely unknown. In this study, we show that Tbx3 was dramatically upregulated in clinical HCC samples and that elevated expression of Tbx3 promoted cancer progression. To determine the underlying mechanism, systematic glycine scan mutagenesis and deletion assays were performed. We identified two critical motifs, 585LFSYPYT591 and 604HRH606, that contribute to the repression of transcriptional activity. These motifs are also essential for Tbx3 to promote cell migration and metastasis both in vitro and in vivo via the suppression of E-cadherin expression. More importantly, Tbx3 directly interacts with HDAC5 via these motifs, and an HDAC inhibitor blocks Tbx3-mediated cell migration and the downregulation of E-cadherin in HCC. As Tbx3 is involved in the carcinogenesis of multiple types of human cancers, our findings suggest an important target for anti-cancer drug development. A regulatory protein that represses gene activity interacts with an enzyme involved in chromosome remodeling to promote the migration and metastasis of liver cancer cells. Ming-Liang He from the City University of Hong Kong and colleagues found that levels of the T-box transcription factor Tbx3 were dramatically increased in tissue biopsies of liver tumors. They injected Tbx3-expressing human liver cancer cells into mice and saw a positive correlation between Tbx3 activity and cancer progression. By mutating and deleting parts of Tbx3, the researchers identified two particular stretches of the protein that bind histone deacetylase 5, an enzyme involved in ensuring DNA coils, are wound tight to suppress gene activity. This interaction is needed for Tbx3’s tumor-promoting function and may be targetable with drugs in order to prevent metastasis in patients with aggressive liver cancer.

The dual-inhibitory effect of miR-338-5p on the multidrug resistance and cell growth of hepatocellular carcinoma

Abstract: Chemotherapeutic treatments against hepatocellular carcinoma (HCC) are necessary for both inoperable patients to improve prospects for survival and surgery patients to improve the outcome after surgical resection. However, multidrug resistance (MDR) is a major obstacle to obtaining desirable results. Currently, increasing the chemotherapy sensitivity of tumor cells or discovering novel tumor inhibitors is an effective therapeutic strategy to solve this issue. In the present study, we uncovered the dual-inhibitory effect of miR-338-5p: on the one hand, it could downregulate ABCB1 expression and sensitize HCC cells to doxorubicin and vinblastine by directly targeting the 3'-untranslated region (3'-UTR) of ABCB1, while, on the other hand, it could suppress the proliferation of HCC cells by directly targeting the 3'-UTR of EGFR and reducing EGFR expression. Since EGFR regulates ABCB1 levels, the indirect action of miR-338-5p in ABCB1 modulation was revealed, in which miR-338-5p inhibits ABCB1 expression by targeting the EGFR/ERK1/2 signaling pathway. These data indicate that the miR-338-5p/EGFR/ABCB1 regulatory loop plays a critical role in HCC, and a negative correlation between miR-338-5p and EGFR or ABCB1 was also detected in HCC clinical samples. In conclusion, these findings reveal a critical role for miR-338-5p in the regulation of MDR and proliferation of HCC, suggesting the potential therapeutic implications of miR-338-5p in HCC treatment.

The roles of prostaglandin F2 in regulating the expression of matrix metalloproteinase-12 via an insulin growth factor-2-dependent mechanism in sheared chondrocytes.

Abstract: Osteoarthritis (OA) was recently identified as being regulated by the induction of cyclooxygenase-2 (COX-2) in response to high fluid shear stress. Although the metabolic products of COX-2, including prostaglandin (PG)E2, 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2), and PGF2α, have been reported to be effective in regulating the occurrence and development of OA by activating matrix metalloproteinases (MMPs), the roles of PGF2α in OA are largely overlooked. Thus, we showed that high fluid shear stress induced the mRNA expression of MMP-12 via cyclic (c)AMP- and PGF2α-dependent signaling pathways. Specifically, we found that high fluid shear stress (20 dyn/cm2) significantly increased the expression of MMP-12 at 6 h ( > fivefold), which then slightly decreased until 48 h ( > threefold). In addition, shear stress enhanced the rapid synthesis of PGE2 and PGF2α, which generated synergistic effects on the expression of MMP-12 via EP2/EP3-, PGF2α receptor (FPR)-, cAMP- and insulin growth factor-2 (IGF-2)-dependent phosphatidylinositide 3-kinase (PI3-K)/protein kinase B (AKT), c-Jun N-terminal kinase (JNK)/c-Jun, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-activating pathways. Prolonged shear stress induced the synthesis of 15d-PGJ2, which is responsible for suppressing the high levels of MMP-12 at 48 h. These in vitro observations were further validated by in vivo experiments to evaluate the mechanisms of MMP-12 upregulation during the onset of OA by high fluid shear stress. By delineating this signaling pathway, our data provide a targeted therapeutic basis for combating OA. Shear stress induces cartilage cells to produce hormone-like molecules that activate the expression of an enzyme implicated in the development of osteoarthritis, a degenerative joint disease. Pu Wang and colleagues from Northeastern University in Shenyang, China, exposed human cartilage cells to high fluid shear stress for up to 2 days. This frictional strain rapidly stimulated the production of a proinflammatory enzyme, COX-2, which in turn promoted the synthesis of two hormone-like substances, called prostaglandins. These prostaglandins, PGE2 and PGF2α, then induced expression of an osteoarthritis-associated enzyme called MMP-12 that destroys the supporting structure that surrounds cartilage cells. The researchers, working both in human cells and in mouse models, further delineated several intermediate signaling molecules in the pathway linking shear stress with MMP-12 activation, thereby revealing several new potential drug targets for combating osteoarthritis in patients.

TdIF1: a putative oncogene in NSCLC tumor progression

Abstract: TdT-interacting factor 1 (TdIF1) is a ubiquitously expressed DNA- and protein-binding protein that directly binds to terminal deoxynucleotidyl transferase (TdT) polymerase. Little is known about the functional role of TdIF1 in cancer cellular signaling, nor has it previously been identified as aberrant in any type of cancer. We report here for the first time that TdIF1 is abundantly expressed in clinical lung cancer patients and that high expression of TdIF1 is associated with poor patient prognosis. We further established that TdIF1 is highly expressed in human non-small cell lung cancer (NSCLC) cell lines compared to a normal lung cell line. shRNA-mediated gene silencing of TdIF1 resulted in the suppression of proliferation and anchorage-independent colony formation of the A549 adenocarcinoma cell line. Moreover, when these TdIF1-silenced cells were used to establish a mouse xenograft model of human NSCLC, tumor size was greatly reduced. These data suggest that TdIF1 is a potent regulator of lung tumor development. Several cell cycle-related and tumor growth signaling pathways, including the p53 and HDAC1/2 pathways, were identified as participating in the TdIF1 signaling network by in silico analysis. Microarray, transcriptome and protein-level analyses validated p53 and HDAC1/2 modulation upon TdIF1 downregulation in an NSCLC cellular model. Moreover, several other cell cycle regulators were affected at the transcript level by TdIF1 silencing, including an increase in CDKN1A/p21 transcripts. Taken together, these results indicate that TdIF1 is a bona fide tumor-promoting factor in NSCLC and a potential target for therapy.

Counterbalance: modulation of VEGF/VEGFR activities by TNFSF15.

Abstract: Vascular hyperpermeability occurs in angiogenesis and several pathobiological conditions, producing elevated interstitial fluid pressure and lymphangiogenesis. How these closely related events are modulated is a fundamentally important question regarding the maintenance of vascular homeostasis and treatment of disease conditions such as cancer, stroke, and myocardial infarction. Signals mediated by vascular endothelial growth factor receptors, noticeably VEGFR-1, -2, and -3, are centrally involved in the promotion of both blood vessel and lymphatic vessel growth. These signaling pathways are counterbalanced or, in the case of VEGFR3, augmented by signals induced by tumor necrosis factor superfamily-15 (TNFSF15). TNFSF15 can simultaneously downregulate membrane-bound VEGFR1 and upregulate soluble VEGFR1, thus changing VEGF/VEGFR1 signals from pro-angiogenic to anti-angiogenic. In addition, TNFSF15 inhibits VEGF-induced VEGFR2 phosphorylation, thereby curbing VEGFR2-mediated enhancement of vascular permeability. Third, and perhaps more interestingly, TNFSF15 is capable of stimulating VEGFR3 gene expression in lymphatic endothelial cells, thus augmenting VEGF-C/D-VEGFR3-facilitated lymphangiogenesis. We discuss the intertwining relationship between the actions of TNFSF15 and VEGF in this review.

Detection of PRMT1 inhibitors with stopped flow fluorescence

Abstract: Protein arginine methyltransferases (PRMTs) are crucial epigenetic regulators in eukaryotic organisms that serve as histone writers for chromatin remodeling. PRMTs also methylate a variety of non-histone protein substrates to modulate their function and activity. The development of potent PRMT inhibitors has become an emerging and imperative research area in the drug discovery field to provide novel therapeutic agents for treating diseases and as tools to investigate the biological functions of PRMTs. PRMT1 is the major type I enzyme that catalyzes the formation of asymmetric dimethyl arginine, and PRMT1 plays important regulatory roles in signal transduction, transcriptional activation, RNA splicing, and DNA repair. Aberrant expression of PRMT1 is found in many types of cancers, pulmonary diseases, cardiovascular disease, diabetes, and renal diseases. PRMT1 is a highly promising target for therapeutic development. We created a stopped flow fluorescence-based assay for PRMT1 inhibitor detection and characterization that has the advantages of being homogeneous, nonradioactive, and mix-and-measure in nature, allowing for continuous measurement of the methylation reaction and its inhibition. To our knowledge, this is the first continuous assay for PRMT1 reaction detection and inhibitor characterization. The approach is not only capable of quantitatively determining the potency (IC50) of PRMT1 inhibitors but can also distinguish cofactor-competitive inhibitors, substrate-competitive inhibitors, and mixed-type inhibitors.