TPCA-1 is a direct dual inhibitor of STAT3 and NF-κB and regresses mutant EGFR-associated human non-small cell lung cancers

Signal Transducer and Activator of Transcription Protein 3 (STAT3): An Update on its Direct Inhibitors as Promising Anticancer Agents

BACKGROUND

Since Signal Transducer and Activator of Transcription 3 (STAT3) is a transcription factor which plays an important role in multiple aspects of cancer, including progression and migration, and it is constitutively activated in various human tumors, STAT3 inhibition has emerged as a validated strategy for the treatment of several malignancies. The aim of this review is to provide an update on the identification of new promising direct inhibitors targeting STAT3 domains, as potential anticancer agents.

METHODS

A thorough literature search focused on recently reported STAT3 direct inhibitors was undertaken. We considered the relevant developments regarding the STAT3 domains, which have been identified as potential drug targets.

RESULTS

In detail, 135 peer-reviewed papers and 7 patents were cited; the inhibitors we took into account targeted the DNA binding domain (compounds were grouped into natural derivatives, small molecules, peptides, aptamers and oligonucleotides), the SH2 binding domain (natural, semi-synthetic and synthetic compounds) and specific residues, like cysteines (natural, semi-synthetic, synthetic compounds and dual inhibitors) and tyrosine 705.

CONCLUSION

The huge number of direct STAT3 inhibitors recently identified demonstrates a strong interest in the investigation of this target, although it represents a challenging task considering that no drug targeting this enzyme is currently available for anticancer therapy. Notably, many studies on the available inhibitors evidenced that some of them possess a dual mechanism of action.

Hypoxia induces rapid, STAT3 and ROS dependent, mitochondrial translocation of RelA(p65) and IκBα

The nuclear factor-κB (NF-κB) family of transcription factors can directly or indirectly regulate many important areas of biology, including immunity, inflammation and cell survival. One intriguing aspect of NF-κB crosstalk with other cell signalling pathways is its regulation of mitochondrial biology, including biogenesis, metabolism and apoptosis. In addition to regulating the expression of mitochondrial genes encoded in the nucleus, NF-κB signalling components are also found within mitochondria themselves and associated with mitochondrial DNA. However, complete biochemical analysis of mitochondrial and sub-mitochondrial localisation of all NF-κB subunits has not been undertaken. Here, we show that only the RelA NF-κB subunit and its inhibitor IκBα reside within mitochondria, whilst p50 is found in the endoplasmic reticulum (ER). Fractionation of mitochondria revealed that only RelA was found in the mitoplast, the location of the mtDNA. We demonstrate that hypoxia leads to a very rapid but transient accumulation of RelA and IκBα in mitochondria. This effect required reactive oxygen species (ROS) but was not dependent on the hypoxia sensing transcription factor subunit HIF1α or intracellular Ca2+ release. We also observed rapid mitochondrial localisation of transcription factor STAT3 following hypoxia. Inhibition of STAT3 blocked RelA and IκBα mitochondrial localisation revealing a previously unknown aspect of crosstalk between these key cellular regulators.

Osimertinib and pterostilbene in EGFR-mutation-positive non-small cell lung cancer (NSCLC)

Monotherapy with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) still leads to incomplete responses in most EGFR-mutation positive non-small cell lung cancer (NSCLC) patients, often due to acquired resistance through activation of parallel compensatory pathways. We have previously shown that co-targeting EGFR, signal transducer and activator of transcription 3 (STAT3), and Src-yes-associated protein 1 (YAP1) was highly synergistic in vitro and in vivo. In the present study, we treated EGFR-mutation positive cell lines with the combination of osimertinib plus a natural compound, pterostilbene, which has been reported to abrogate Src and STAT3 activation.

Methods: Cell viability assays and immunoblotting were performed to reveal the mechanisms of action of pterostilbene, osimertinib and pterostilbene plus osimertinib in five EGFR-mutation positive NSCLC and one triple negative breast cancer (TNBC) cell lines.

Results: Osimertinib plus pterostilbene yielded synergistic effects in all EGFR-mutation positive NSCLC cell lines investigated. Surprisingly, pterostilbene alone did not inhibit, nor downregulate Src phosphorylation in the EGFR-mutation positive NSCLC cell lines or the TNBC cell line, MDA-MB-231. However, the double combination of osimertinib plus pterostilbene reversed the osimertinib-induced STAT3, YAP1, and CUB domain-containing protein-1 (CDCP1) phosphorylation and slightly suppressed Src phosphorylation in PC9 and H1975 cells.

Conclusion: The results of this study indicate that pterostilbene may be used to abrogate the activated resistance pathways of single osimertinib treatment in EGFR-mutation positive NSCLC. Future studies should focus on in vivo translation and confirmation of these results.

Hyaluronic Acid-Modified and TPCA-1-Loaded Gold Nanocages Alleviate Inflammation

Gold nanocages (AuNCs) are biocompatible and porous nanogold particles that have been widely used in biomedical fields. In this study, hyaluronic acid (HA) and peptide- modified gold nanocages (HA-AuNCs/T/P) loaded with 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1) were prepared to investigate their potential for combating inflammation. TPCA-1 was released from AuNCs, intracellularly when HA was hydrolyzed by hyaluronidase. HA-AuNCs/T/P show a much higher intracellular uptake than AuNCs/T/P, and exhibit a much higher efficacy on the suppression of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) than free TPCA-1, suggesting great improvement to the anti-inflammatory efficacy of TPCA-1 through the application of AuNCs. HA-AuNCs/T/P can also reduce the production of reactive oxygen species in inflammatory cells. This study suggests that HA-AuNCs/T/P may be potential agents for anti-inflammatory treatment, and are worthy of further investigation.

The Selection of NFκB Inhibitors to Block Inflammation and Induce Sensitisation to FasL-Induced Apoptosis in HNSCC Cell Lines Is Critical for Their Use as a Prospective Cancer Therapy

Inflammation is a central aspect of tumour biology and can contribute significantly to both the origination and progression of tumours. The NFκB pathway is one of the most important signal transduction pathways in inflammation and is, therefore, an excellent target for cancer therapy. In this work, we examined the influence of four NFκB inhibitors—Cortisol, MLN4924, QNZ and TPCA1—on proliferation, inflammation and sensitisation to apoptosis mediated by the death ligand FasL in the HNSCC cell lines PCI1, PCI9, PCI13, PCI52 and SCC25 and in the human dermal keratinocyte cell line HaCaT. We found that the selection of the inhibitor is critical to ensure that cells do not respond by inducing counteracting activities in the context of cancer therapy, e.g., the extreme IL-8 induction mediated by MLN4924 or FasL resistance mediated by Cortisol. However, TPCA1 was qualified by this in vitro study as an excellent therapeutic mediator in HNSCC by four positive qualities: (1) proliferation was inhibited at low μM-range concentrations; (2) TNFα-induced IL-8 secretion was blocked; (3) HNSCC cells were sensitized to TNFα-induced cell death; and (4) FasL-mediated apoptosis was not disrupted.

Anti-inflammatory role of TPCA-1 encapsulated nanosomes in porcine chondrocytes against TNF-α stimulation

In this study, we evaluated the hypothesis that immunonanosomes carrying the drug [5-(p-Fluorophenyl)-2-ureido]thiophene-3-carboxamide (TPCA-1) will help in reducing nuclear factor-kappaB (NF-κB)-associated inflammation in porcine chondrocytes against tumor necrosis factor-alpha (TNF-α)-induced stress. The nanosomes were tagged with monoclonal anti-type II collagen (MabCII) antibody to specifically target the exposed type II collagen in cartilage matrix. TPCA-1 at a concentration of 10 µM significantly reduced expression of the matrix-degrading enzyme, Matrix metalloproteinase-13 (MMP-13) and blocked the p65 nuclear translocation. In comparison to the TPCA-1 solution alone, the TPCA-1 nanosomes were found to be more effective in reducing the cellular toxicity, oxidative stress and inflammation in chondrocytes treated with TNF-α. In addition, TPCA-1 nanosomes were more effective in reducing the gene expression of hypoxia-inducible factor-2alpha (HIF-2α) that in turn is associated with the regulation of MMP-13 gene. TPCA-1 nanosomes significantly reduced expression of both these genes. The data also showed that TPCA-1 did not attenuate the down-regulated gene expression levels of anabolic genes aggrecan (ACAN) and collagen type II alpha (COL2A1). In conclusion, this study showed that TPCA-1 nanosomes carrying a dose of 10 µM TPCA-1 can effectively increase the survival of cultured porcine chondrocytes against TNF-α-induced stress. The findings of this study could be used to develop nanosome-based drug delivery systems (DDSs) for animal model of OA. Moreover, the approach presented here can be further utilized in other studies for targeted delivery of the drug of interest at a cellular level.

Self-Adjusting Cytokine Neutralizer Cells as a Closed-Loop Delivery System of Anti-Inflammatory Biologicals

The cytokines tumor necrosis factor α (TNFα) and interleukin 1 β (IL-1β) are both strong NF-κB activators and some of the first cytokines to be released in an inflammatory process. TNFα and IL-1β are present in many autoimmune diseases, such as rheumatoid arthritis (RA). TNFα and IL-1β-blocking therapies are quite successful and established in the treatment of RA, but may also be promising in other diseases. For the treatment of recurring autoimmune diseases, strong controlled sensor-effector cells inhibiting TNFα or IL-1β appear highly predestined. Such cells detect a disease biomarker and autonomously react with the dose-dependent production of therapeutic proteins. Hence, we aim to harness and assemble the interactions of TNFα, IL-1β, and NF-κB, which are an ideal match for synthetic biology-based circuits to rewire the transmission to approved TNFα- or IL-1β-blocking biologicals. Considering the high impact of environmental influences on the dynamics of cell-based systems, we established closed-loop controllable cytokine neutralizer cells, monitoring cytokine levels and autonomously delivering powerful biologicals. This real-time processing system may provide dose-dependent drug delivery, which may be tailored for prospective cell and gene therapies against RA, and may offer a more personalized medicine than calculated drug dosing based on body weight.

Targeting IKKβ in Cancer: Challenges and Opportunities for the Therapeutic Utilisation of IKKβ Inhibitors

Deregulated NF-κB signalling is implicated in the pathogenesis of numerous human inflammatory disorders and malignancies. Consequently, the NF-κB pathway has attracted attention as an attractive therapeutic target for drug discovery. As the primary, druggable mediator of canonical NF-κB signalling the IKKβ protein kinase has been the historical focus of drug development pipelines. Thousands of compounds with activity against IKKβ have been characterised, with many demonstrating promising efficacy in pre-clinical models of cancer and inflammatory disease. However, severe on-target toxicities and other safety concerns associated with systemic IKKβ inhibition have thus far prevented the clinical approval of any IKKβ inhibitors. This review will discuss the potential reasons for the lack of clinical success of IKKβ inhibitors to date, the challenges associated with their therapeutic use, realistic opportunities for their future utilisation, and the alternative strategies to inhibit NF-κB signalling that may overcome some of the limitations associated with IKKβ inhibition.

Evidence of Intertissue Differences in the DNA Damage Response and the Pro-oncogenic Role of NF-κB in Mice with Disengaged BRCA1-PALB2 Interaction

The BRCA1-PALB2-BRCA2 axis plays an essential role in DNA homologous recombination repair, defect in which drives genome instability and cancer development. How cells with defects in this pathway respond to DNA damage in vivo and how tumors develop from these cells remain poorly defined. Here, we analyzed several aspects of the DNA damage response in multiple tissues of Palb2-mutant mice in which the interaction between PALB2 and BRCA1 is disengaged. Without any challenge, the mutant mice showed increased endogenous DNA damage. Following ionizing radiation, the mutant mice displayed higher levels of DNA breaks and stronger induction of p53 and p21, but continued DNA synthesis, reduced apoptosis, and accelerated tumor development. The differences in p21 induction, DNA synthesis, and apoptosis between wild-type and mutant mice were substantially more pronounced in the mammary gland than in the intestine, suggesting a potential contributing factor to the increased risk and the tissue specificity of BRCA/PALB2-associated tumor development. Moreover, the mutant mice showed higher levels of reactive oxygen species and constitutive activation of NF-κB, an antiapoptotic transcription factor inducible by both DNA damage and oxidative stress. Treatment of the mutant mice with an inhibitor of NF-κB reactivated apoptosis and delayed tumor development following radiation. Thus, our results also suggest a prosurvival and pro-oncogenic role of NF-κB in PALB2-mutant cells.Significance: This study explores novel tumor suppression mechanisms of the BRCA1-PALB2 DNA damage response pathway and implicates NF-κB activation as a protumorogenic event and possible therapeutic target. Cancer Res; 78(14); 3969-81. ©2018 AACR.

Activation of signal transducer and activator of transcription 3 (STAT3) signaling in EGFR mutant non-small-cell lung cancer (NSCLC)

Gefitinib, erlotinib or afatinib are the current treatment for non-small-cell lung cancer (NSCLC) harboring an activating mutation of the epidermal growth factor receptor (EGFR), but less than 5% of patients achieve a complete response and the median progression-free survival is no longer than 12 months. Early adaptive resistance can occur as soon as two hours after starting treatment by activating signal transducer and activation of transcription 3 (STAT3) signaling. We investigated the activation of STAT3 in a panel of gefitinib-sensitive EGFR mutant cell lines, and gefitinib-resistant PC9 cell lines developed in our laboratory. Afatinib has great activity in gefitinib-sensitive as well as in gefitinib-resistant EGFR mutant NSCLC cell lines. However, afatinib therapy causes phosphorylation of STAT3 tyrosine 705 (pSTAT3_Tyr705) and elevation of STAT3 and RANTES mRNA levels. The combination of afatinib with TPCA-1 (a STAT3 inhibitor) ablated pSTAT3_Tyr705 and down-regulated STAT3 and RANTES mRNA levels with significant growth inhibitory effect in both gefitinib-sensitive and gefitinib-resistant EGFR mutant NSCLC cell lines. Aldehyde dehydrogenase positive (ALDH⁺) cells were still observed with the combination at the time that Hairy and Enhancer of Split 1 (HES1) mRNA expression was elevated following therapy. Although the combination of afatinib with STAT3 inhibition cannot eliminate the potential problem of a remnant cancer stem cell population, it represents a substantial advantage and opportunity to further prolong progression free survival and probably could increase the response rate in comparison to the current standard of single therapy.

Silibinin is a direct inhibitor of STAT3

We herein combined experimental and computational efforts to delineate the mechanism of action through which the flavonolignan silibinin targets STAT3. Silibinin reduced IL-6 inducible, constitutive, and acquired feedback activation of STAT3 at tyrosine 705 (Y705). Silibinin attenuated the inducible phospho-activation of Y705 in GFP-STAT3 genetic fusions without drastically altering the kinase activity of the STAT3 upstream kinases JAK1 and JAK2. A comparative computational study based on docking and molecular dynamics simulation over 14 different STAT3 inhibitors (STAT3i) predicted that silibinin could directly bind with high affinity to both the Src homology-2 (SH2) domain and the DNA-binding domain (DBD) of STAT3. Silibinin partially overlapped with the cavity occupied by other STAT3i in the SH2 domain to indirectly prevent Y705 phosphorylation, yet showing a unique binding mode. Moreover, silibinin was the only STAT3i predicted to establish direct interactions with DNA in its targeting to the STAT3 DBD. The prevention of STAT3 nuclear translocation, the blockade of the binding of activated STAT3 to its consensus DNA sequence, and the suppression of STAT3-directed transcriptional activity confirmed silibinin as a direct STAT3i. The unique characteristics of silibinin as a bimodal SH2- and DBD-targeting STAT3i make silibinin a promising lead for designing new, more effective STAT3i.

Molecular cross-talk of IL-6 in tumors and new progress in combined therapy

IL-6, a cytokine activated by type I interferons (IFNs), is encoded by the IL-6 gene, and secreted by T cells and macrophages. It serves many purposes in the human body and is significant to pathological and physiological activities, such as acute inflammatory responses, autoimmune diseases, and tumor formation. The wide range of IL-6 actions on tumors rely on more than one specific pathway. Advances in modern research have determined that to fulfill its complex physiological functions, IL-6 must be involved in cross-talk with a number of other molecular pathways. Therefore, it is important to clarify the comprehensive pathway network associated with IL-6 activity and to explore the mechanisms to inhibit its pathological activity in order to develop corresponding treatment plans. This study is a simple review of the pathological and physiological actions of IL-6 on the human body. It explains in detail the molecular pathways involved in cross-talk between IL-6 and tumors, summarizing and discussing the latest progress made in IL-6-related internal medicine treatments in recent years, including chemotherapies, targeted therapies, and immunotherapies. Our results provide new insight into the treatment of tumors.

Targeting IκappaB kinases for cancer therapy

The inhibitory kappa B kinases (IKKs) and IKK related kinases are crucial regulators of the pro-inflammatory transcription factor, nuclear factor kappa B (NF-κB). The dysregulation in the activities of these kinases has been reported in several cancer types. These kinases are known to regulate survival, proliferation, invasion, angiogenesis, and metastasis of cancer cells. Thus, IKK and IKK related kinases have emerged as an attractive target for the development of cancer therapeutics. Several IKK inhibitors have been developed, few of which have advanced to the clinic. These inhibitors target IKK either directly or indirectly by modulating the activities of other signaling molecules. Some inhibitors suppress IKK activity by disrupting the protein-protein interaction in the IKK complex. The inhibition of IKK has also been shown to enhance the efficacy of conventional chemotherapeutic agents. Because IKK and NF-κB are the key components of innate immunity, suppressing IKK is associated with the risk of immune suppression. Furthermore, IKK inhibitors may hit other signaling molecules and thus may produce off-target effects. Recent studies suggest that multiple cytoplasmic and nuclear proteins distinct from NF-κB and inhibitory κB are also substrates of IKK. In this review, we discuss the utility of IKK inhibitors for cancer therapy. The limitations associated with the intervention of IKK are also discussed.

miR147b: A novel key regulator of interleukin 1 beta-mediated inflammation in human astrocytes

Astrocytes are important mediators of inflammatory processes in the brain and seem to play an important role in several neurological disorders, including epilepsy. Recent studies show that astrocytes produce several microRNAs, which may function as crucial regulators of inflammatory pathways and could be used as therapeutic target. We aim to study which miRNAs are produced by astrocytes during IL-1β mediated inflammatory conditions in vitro, as well as their functional role and to validate these findings in human epileptogenic brain tissue. Sequencing was used to assess miRNA and mRNA expression in IL-1β-stimulated human fetal astrocyte cultures. miRNAs were overexpressed in cell cultures using miRNA mimics. Expression of miRNAs in resected brain tissue from patients with tuberous sclerosis complex or temporal lobe epilepsy with hippocampal sclerosis was examined using in situ hybridization. Two differentially expressed miRNAs were found: miR146a and miR147b, which were associated with increased expression of genes related to the immune/inflammatory response. As previously reported for miR146a, overexpression of miR147b reduced the expression of the pro-inflammatory mediators IL-6 and COX-2 after IL-1β stimulation in both astrocyte and tuberous sclerosis complex cell cultures. miR146a and miR147b overexpression decreased proliferation of astrocytes and promoted neuronal differentiation of human neural stem cells. Similarly to previous evidence for miR146a, miR147b was increased expressed in astrocytes in epileptogenic brain. Due to their anti-inflammatory effects, ability to restore aberrant astrocytic proliferation and promote neuronal differentiation, miR146a and miR147b deserve further investigation as potential therapeutic targets in neurological disorders associated with inflammation, such as epilepsy.

Proscillaridin A Promotes Oxidative Stress and ER Stress, Inhibits STAT3 Activation, and Induces Apoptosis in A549 Lung Adenocarcinoma Cells

Cardiac glycosides are natural compounds used for the treatment of cardiovascular disorders. Although originally prescribed for cardiovascular diseases, more recently, they have been rediscovered for their potential use in the treatment of cancer. Proscillaridin A (PSD-A), a cardiac glycoside component of Urginea maritima, has been reported to exhibit anticancer activity. However, the cellular targets and anticancer mechanism of PSD-A in various cancers including lung cancer remain largely unexplored. In the present study, we found that PSD-A inhibits growth and induces apoptosis in A549 lung adenocarcinoma cells. The anticancer activity of PSD-A was found to be associated with the activation of JNK, induction of ER stress, mitochondrial dysfunction, and inhibition of STAT3 activation. PSD-A induces oxidative stress as evidenced from ROS generation, GSH depletion, and decreased activity of TrxR1. PSD-A-mediated ER stress was verified by increased phosphorylation of eIF2α and expression of its downstream effector proteins ATF4, CHOP, and caspases-4. PSD-A triggered apoptosis by inducing JNK (1/2) activation, increasing bax/bcl-2 ratio, dissipating mitochondrial membrane potential, and inducing cleavage of caspases and PARP. Further study revealed that PSD-A inhibits both constitutive and inducible STAT3 activations and decreases STAT3 DNA-binding activity. Moreover, PSD-A-mediated inhibition of STAT3 activation was found to be associated with increased SHP-1 expression, decreased phosphorylation of Src, and binding of PSD-A with STAT3 SH2 domain. Finally, STAT3 knockdown by shRNA inhibited growth and enhanced apoptotic efficacy of PSD-A. Taken together, the data suggest that PSD-A could be developed into a potential therapeutic agent against lung adenocarcinoma.

Santamarine Inhibits NF-κB Activation and Induces Mitochondrial Apoptosis in A549 Lung Adenocarcinoma Cells via Oxidative Stress

Santamarine (STM), a sesquiterpene lactone component of Magnolia grandiflora and Ambrosia confertiflora, has been shown to possess antimicrobial, antifungal, antibacterial, anti-inflammatory, and anticancer activities. However, no study has yet been conducted to investigate the molecular mechanism of STM-mediated anticancer activity. In the present study, we found that STM inhibits growth and induces apoptosis in A549 lung adenocarcinoma cells through induction of oxidative stress. STM induces oxidative stress by promoting reactive oxygen species (ROS) generation, depleting intracellular glutathione (GSH), and inhibiting thioredoxin reductase (TrxR) activity in a dose-dependent manner. Further mechanistic study demonstrated that STM induces apoptosis by modulation of Bax/Bcl-2 expressions, disruption of mitochondrial membrane potential, activation of caspase-3, and cleavage of PARP in a dose-dependent manner. Moreover, STM inhibited the constitutive and inducible translocation of NF-κBp65 into the nucleus. IKK-16 (I-κB kinase inhibitor) augmented the STM-induced apoptosis, indicating that STM induces apoptosis in A549 cells at least in part through NF-κB inhibition. Finally, STM-induced apoptosis and expressions of apoptosis regulators were effectively inhibited by thiol antioxidant N-acetyl-L-cysteine (NAC), indicating that STM exerts its anticancer effects mainly through oxidative stress. To the best of our knowledge, this is the first report providing evidence of anticancer activity and molecular mechanism of STM.

Matrine increases the inhibitory effects of afatinib on H1975 cells via the IL‑6/JAK1/STAT3 signaling pathway

Resistance to epidermal growth factor receptor (EGFR) inhibitors is of primary concern in the treatment of non-small-cell lung cancer (NSCLC) with EGFR mutations. To investigate the effects of matrine on H1975 cells and to examine a novel, potential treatment option for NSCLC, the present study measured cell viability, apoptotic rate, interleukin 6 (IL-6) expression and activation of the janus kinase (JAK) 1/signal transducer and activator of transcription (STAT)3 signaling pathway in cells treated with or without matrine, in the presence or absence of afatinib. The results demonstrated that matrine treatment inhibited cell growth, decreased B-cell lymphoma 2 (Bcl-2) expression and induced apoptosis. Matrine treatment additionally decreased the mRNA and protein levels of IL-6 and inhibited activation of the JAK1/STAT3 signaling pathway in H1975 cells in a dose-dependent manner. H1975 cells treated with IL-6 small interfering RNA exhibited a decrease in Bcl-2 expression levels and cell viability. Treatment with a combination of matrine and afatinib demonstrated increased inhibitory effects on the growth rate of H1975 cells. The findings of the present study suggested that matrine treatment decreases IL-6 expression, inhibits activation of the JAK1/STAT3 signaling pathway, reduces the expression levels of Bcl-2 and inhibits cell growth. Furthermore, matrine treatment was demonstrated to increase the inhibitory effects of afatinib on H1975 cells with the T790M EGFR mutation.

Co-activation of STAT3 and YES-Associated Protein 1 (YAP1) Pathway in EGFR-Mutant NSCLC

Background

The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC) is limited by adaptive activation of cell survival signals. We hypothesized that both signal transducer and activator of transcription 3 (STAT3) and Src-YES-associated protein 1 (YAP1) signaling are dually activated during EGFR TKI treatment to limit therapeutic response.

Methods

We used MTT and clonogenic assays, immunoblotting, and quantitative polymerase chain reaction to evaluate the efficacy of EGFR TKI alone and in combination with STAT3 and Src inhibition in three EGFR-mutant NSCLC cell lines. The Chou-Talalay method was used for the quantitative determination of drug interaction. We examined tumor growth inhibition in one EGFR-mutant NSCLC xenograft model (n = 4 mice per group). STAT3 and YAP1 expression was evaluated in tumors from 119 EGFR-mutant NSCLC patients (64 in an initial cohort and 55 in a validation cohort) by quantitative polymerase chain reaction. Kaplan-Meier and Cox regression analyses were used to assess the correlation between survival and gene expression. All statistical tests were two-sided.

Results

We discovered that lung cancer cells survive initial EGFR inhibitor treatment through activation of not only STAT3 but also Src-YAP1 signaling. Cotargeting EGFR, STAT3, and Src was synergistic in two EGFR-mutant NSCLC cell lines with a combination index of 0.59 (95% confidence interval [CI] = 0.54 to 0.63) for the PC-9 and 0.59 (95% CI = 0.54 to 0.63) for the H1975 cell line. High expression of STAT3 or YAP1 predicted worse progression-free survival (hazard ratio [HR] = 3.02, 95% CI = 1.54 to 5.93, P = .001, and HR = 2.57, 95% CI = 1.30 to 5.09, P = .007, respectively) in an initial cohort of 64 EGFR-mutant NSCLC patients treated with firstline EGFR TKIs. Similar results were observed in a validation cohort.

Conclusions

Our study uncovers a coordinated signaling network centered on both STAT3 and Src-YAP signaling that limits targeted therapy response in lung cancer and identifies an unforeseen rational upfront polytherapy strategy to minimize residual disease and enhance clinical outcomes.

Early spatiotemporal-specific changes in intermediate signals are predictive of cytotoxic sensitivity to TNFα and co-treatments

Signaling pathways can generate different cellular responses to the same cytotoxic agents. Current quantitative models for predicting these differential responses are usually based on large numbers of intracellular gene products or signals at different levels of signaling cascades. Here, we report a study to predict cellular sensitivity to tumor necrosis factor alpha (TNFα) using high-throughput cellular imaging and machine-learning methods. We measured and compared 1170 protein phosphorylation events in a panel of human lung cancer cell lines based on different signals, subcellular regions, and time points within one hour of TNFα treatment. We found that two spatiotemporal-specific changes in an intermediate signaling protein, p90 ribosomal S6 kinase (RSK), are sufficient to predict the TNFα sensitivity of these cell lines. Our models could also predict the combined effects of TNFα and other kinase inhibitors, many of which are not known to target RSK directly. Therefore, early spatiotemporal-specific changes in intermediate signals are sufficient to represent the complex cellular responses to these perturbations. Our study provides a general framework for the development of rapid, signaling-based cytotoxicity screens that may be used to predict cellular sensitivity to a cytotoxic agent, or identify co-treatments that may sensitize or desensitize cells to the agent.

STAT3/NF-κB-Regulated Lentiviral TK/GCV Suicide Gene Therapy for Cisplatin-Resistant Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) represents approximately 20% of all breast cancers and appears resistance to conventional cytotoxic chemotherapy, demonstrating a particularly poor prognosis and a significantly worse clinical outcome than other types of cancer. Suicide gene therapy has been used for the in vivo treatment of various solid tumors in recent clinical trials. In tumor microenvironment, STAT3/NF-κB pathways are constitutively activated in stromal cells as well as in cancer stem cells (CSCs). In this study, we have cloned a novel STAT3/NF-κB-based reporter system to drive the expression of herpes simplex virus thymidine kinase (HSV-TK) against breast cancer. Lentiviral vector expressing HSV-TK under the regulation of STAT3/NF-κB fused response element was developed. In this setting, we exploited the constitutive STAT3/NF-κB activation in tumors to achieve higher transgene expression than that driven by a constitutively active CMV promotor in vivo. An orthotropic MDA-MB-231 triple negative breast cancer mouse model was used for evaluating the feasibility of STAT3-NF-κB-TK/GCV suicide gene therapy system.

The basal promoter activity of Lenti-CMV-TK and Lenti-STAT3-NF-κB-TK in MDA-MB-231 cells was compared by ³H-FEAU uptake assay. The Lenti-CMV-TK showed ~5 fold higher ³H-FEAU uptake then Lenti -STAT3-NF-κB-TK. In clonogenic assay, cells expressing Lenti-CMV-TK were 2-fold more sensitive to GCV than Lenti-STAT3-NF-κB-TK transduced cells. In vitro effect of STAT3-NF-κB-induced transgene expression was determined by 10ng/mL TNF-α induction and confirmed by western blot analysis and DsRedm fluorescent microscopy. In vivo evaluation of therapeutic effect by bioluminescence and [¹⁸F]FHBG microPET imaging indicated that Lenti-STAT3-NF-κB-TK showed more tumor growth retardation than Lenti-CMV-TK when GCV (20 mg/kg) was administered. The invasiveness and expression of cancer stem cell markers were both decreased after STAT3/NF-κB-regulated HSV-TK/GCV therapy. Moreover, STAT3/NF-κB signaling targeting could further sensitize tumor cells to cisplatin. This study successfully established a theranositic approach to treat triple-negative breast cancer via STAT3-NF-κB responsive element-driven suicide gene therapy. This platform may also be an alternative strategy to handle with drug-resistant cancer cells.

Notch-1 Confers Chemoresistance in Lung Adenocarcinoma to Taxanes through AP-1/microRNA-451 Mediated Regulation of MDR-1

We previously demonstrated that expression of Notch-1 is associated with poor prognosis in lung adenocarcinoma (LAD) patients. The aim of this study is to reveal whether Notch-1 was associated with Taxanes-resistant LAD and, the underlying mechanisms. We collected 39 patients of advanced LAD treated with Taxanes and found that positive Notch-1 expression is closely related to LAD lymph node metastasis, recurrence and poorer prognosis, and Notch-1 acts as an independent poor prognostic factor in LAD by multivariate analysis with Cox regression model. Then, by using the Docetaxel (DTX)-resistant LAD cell lines that we established previously, we found that Notch-1 contributes to resistance of LAD cells to DTX in vitro, and inhibition of Notch-1 sensitizes LAD to DTX in vivo. We further demonstrated that Notch-1 mediates chemoresistance response and strengthens proliferation capacity in LAD cells partially through negative regulation of miR-451 by transcription factor AP-1. Moreover, we found that MDR-1 is a direct target of miR-451 and influences chemoresistance of LAD cells. Taken together, our data revealed a novel Notch-1/AP-1/miR-451/MDR-1 signaling axis, and suggested a new therapeutic strategy of combining DTX with Notch inhibitors to treat DTX-resistant LAD.

Long Intergenic Noncoding RNAs Mediate the Human Chondrocyte Inflammatory Response and Are Differentially Expressed in Osteoarthritis Cartilage

OBJECTIVE

To identify long noncoding RNAs (lncRNAs), including long intergenic noncoding RNAs (lincRNAs), antisense RNAs, and pseudogenes, associated with the inflammatory response in human primary osteoarthritis (OA) chondrocytes and to explore their expression and function in OA.

METHODS

OA cartilage was obtained from patients with hip or knee OA following joint replacement surgery. Non-OA cartilage was obtained from postmortem donors and patients with fracture of the neck of the femur. Primary OA chondrocytes were isolated by collagenase digestion. LncRNA expression analysis was performed by RNA sequencing (RNAseq) and quantitative reverse transcriptase-polymerase chain reaction. Modulation of lncRNA chondrocyte expression was achieved using LNA longRNA GapmeRs (Exiqon). Cytokine production was measured with Luminex.

RESULTS

RNAseq identified 983 lncRNAs in primary human hip OA chondrocytes, 183 of which had not previously been identified. Following interleukin-1β (IL-1β) stimulation, we identified 125 lincRNAs that were differentially expressed. The lincRNA p50-associated cyclooxygenase 2-extragenic RNA (PACER) and 2 novel chondrocyte inflammation-associated lincRNAs (CILinc01 and CILinc02) were differentially expressed in both knee and hip OA cartilage compared to non-OA cartilage. In primary OA chondrocytes, these lincRNAs were rapidly and transiently induced in response to multiple proinflammatory cytokines. Knockdown of CILinc01 and CILinc02 expression in human chondrocytes significantly enhanced the IL-1-stimulated secretion of proinflammatory cytokines.

CONCLUSION

The inflammatory response in human OA chondrocytes is associated with widespread changes in the profile of lncRNAs, including PACER, CILinc01, and CILinc02. Differential expression of CILinc01 and CIinc02 in hip and knee OA cartilage, and their role in modulating cytokine production during the chondrocyte inflammatory response, suggest that they may play an important role in mediating inflammation-driven cartilage degeneration in OA.

Breaking resistance of pancreatic cancer cells to an attenuated vesicular stomatitis virus through a novel activity of IKK inhibitor TPCA-1

Vesicular stomatitis virus (VSV) is an effective oncolytic virus against most human pancreatic ductal adenocarcinoma (PDAC) cell lines. However, some PDAC cell lines are highly resistant to oncolytic VSV-ΔM51 infection. To better understand the mechanism of resistance, we tested a panel of 16 small molecule inhibitors of different cellular signaling pathways, and identified TPCA-1 (IKK-β inhibitor) and ruxolitinib (JAK1/2 inhibitor), as strong enhancers of VSV-ΔM51 replication and virus-mediated oncolysis in all VSV-resistant PDAC cell lines. Both TPCA-1 and ruxolitinib similarly inhibited STAT1 and STAT2 phosphorylation and decreased expression of antiviral genes MxA and OAS. Moreover, an in situ kinase assay provided biochemical evidence that TPCA-1 directly inhibits JAK1 kinase activity. Together, our data demonstrate that TPCA-1 is a unique dual inhibitor of IKK-β and JAK1 kinase, and provide a new evidence that upregulated type I interferon signaling plays a major role in resistance of pancreatic cancer cells to oncolytic viruses.

Non-small-cell lung cancer

Lung cancer is one of the most frequently diagnosed cancers and is the leading cause of cancer-related death worldwide. Non-small-cell lung cancer (NSCLC), a heterogeneous class of tumours, represents approximately 85% of all new lung cancer diagnoses. Tobacco smoking remains the main risk factor for developing this disease, but radon exposure and air pollution also have a role. Most patients are diagnosed with advanced-stage disease owing to inadequate screening programmes and late onset of clinical symptoms; consequently, patients have a very poor prognosis. Several diagnostic approaches can be used for NSCLC, including X-ray, CT and PET imaging, and histological examination of tumour biopsies. Accurate staging of the cancer is required to determine the optimal management strategy, which includes surgery, radiochemotherapy, immunotherapy and targeted approaches with anti-angiogenic monoclonal antibodies or tyrosine kinase inhibitors if tumours harbour oncogene mutations. Several of these driver mutations have been identified (for example, in epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK)), and therapy continues to advance to tackle acquired resistance problems. Also, palliative care has a central role in patient management and greatly improves quality of life. For an illustrated summary of this Primer, visit: http://go.nature.com/rWYFgg.

Dehydrocrenatidine is a novel janus kinase inhibitor

Janus kinase (JAK) 2 plays a pivotal role in the tumorigenesis of signal transducers and activators of transcription (STAT) 3 constitutively activated solid tumors. JAK2 mutations are involved in the pathogenesis of various types of hematopoietic disorders, such as myeloproliferative disorders, polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Thus, small-molecular inhibitors targeting JAK2 are potent for therapy of these diseases. In this study, we screened 1,062,608 drug-like molecules from the ZINC database and 2080 natural product chemicals. We identified a novel JAK family kinase inhibitor, dehydrocrenatidine, that inhibits JAK-STAT3-dependent DU145 and MDA-MB-468 cell survival and induces cell apoptosis. Dehydrocrenatidine represses constitutively activated JAK2 and STAT3, as well as interleukin-6-, interferon-α-, and interferon-γ-stimulated JAK activity, and STAT phosphorylation, and suppresses STAT3 and STAT1 downstream gene expression. Dehydrocrenatidine inhibits JAKs-JH1 domain overexpression-induced STAT3 and STAT1 phosphorylation. In addition, dehydrocrenatidine inhibits JAK2-JH1 kinase activity in vitro. Importantly, dehydrocrenatidine does not show significant effect on Src overexpression and epidermal growth factor-induced STAT3 activation. Our results indicate that dehydrocrenatidine is a JAK-specific inhibitor.