The RAF-MEK-ERK pathway: targeting ERK to overcome obstacles to effective cancer therapy

LncRNA HOXB-AS3 promotes proliferation, migration, and invasion of gallbladder cancer cells by activating the MEK/ERK pathway

Background

LncRNA HOXB-AS3 are associated with tumor progression in several types of carcinomas, yet, its possibly biological role in gallbladder carcinoma(GBC) remains unclear. Therefore, this study aimed to investigate the biological function of HOXB-AS3 in GBC.

Methods

To know the potential function of HOXB-AS3 in gallbladder carcinoma, real-time polymerase chain reaction was used to detected the expression of HOXB-AS3 in gallbladder carcinoma cells. The colony formation assay and cell counting kit-8 assay was performed to measured cell viability. Flow cytometry was to analyse cell apoptosis and cell cycle. Cell invasion and migration were determined by the transwell invasion assay and wound-healing assay. A nude mice xenograft tumor model was performed to investigate the biological function of HOXB-AS3 in vivo.

Results

The results indicated that HOXB-AS3 was significantly elevated in gallbladder carcinoma tissues and cell lines. We used siHOXB-AS3 to knockdown the expression levels of HOXB-AS3. And knockdown HOXB-AS3 expression depressed gallbladder cancer cell viability and induced cell apoptosis. In addition, the gallbladder carcinoma cell cycle was obviously arrested at the G1 phase. Cell invasion and migration were markedly suppressed following knockdown HOXB-AS3 expression. Furthermore, the features of siHOXB-AS3 in gallbladder cancer cells could be reversed by the ERK1/2 phosphorylation agonist Ro 67-7476. Finally, we confirmed that HOXB-AS3 promoted the growth of transplanted tumors in vivo.

Conclusion

HOXB-AS3 promoted gallbladder carcinoma cell proliferation, invasion and migration by activating the MEK/ERK signaling pathway. HOXB-AS3 contributed to gallbladder cancer tumorigenesis and metastasis, making it a viable therapeutic target for gallbladder cancer treatment.

Progress in RAS-targeted therapeutic strategies: From small molecule inhibitors to proteolysis targeting chimeras

As a widely considerable target in chemical biology and pharmacological research, rat sarcoma (RAS) gene mutations play a critical driving factor in several fatal cancers. Despite the great progress of RAS subtype-specific inhibitors, rapid acquired drug resistance could limit their further clinical applications. Proteolysis targeting chimera (PROTAC) has emerged as a powerful tool to handle "undruggable" targets and exhibited significant therapeutic benefit for the combat of drug resistance. Owing to unique molecular mechanism and binding kinetics, PROTAC is expected to become a feasible strategy to break the bottleneck of classical RAS inhibitors. This review aims to discuss the current advances of RAS inhibitors and especially focus on PROTAC strategy targeting RAS mutations and their downstream effectors for relevant cancer treatment.

Synergistic anticancer effect by targeting CDK2 and EGFR-ERK signaling

The EGFR-RAS-ERK pathway is one of the most important signaling cascades in cell survival, growth, and proliferation. Aberrant activation of this pathway is a common mechanism in various cancers. Here, we report that CDK2 is a novel regulator of the ERK pathway via USP37 deubiquitinase (DUB). Mechanistically, CDK2 phosphorylates USP37, which is required for USP37 DUB activity. Further, USP37 deubiquitinates and stabilizes ERK1/2, thereby enhancing cancer cell proliferation. Thus, CDK2 is able to promote cell proliferation by activating USP37 and, in turn, stabilizing ERK1/2. Importantly, combined CDK1/2 and EGFR inhibitors have a synergetic anticancer effect through the downregulation of ERK1/2 stability and activity. Indeed, our patient-derived xenograft (PDX) results suggest that targeting both ERK1/2 stability and activity kills cancer cells more efficiently even at lower doses of these two inhibitors, which may reduce their associated side effects and indicate a potential new combination strategy for cancer therapy.

Design, Synthesis, and Antiproliferative Activity of New 5-Chloro-indole-2-carboxylate and Pyrrolo[3,4-b]indol-3-one Derivatives as Potent Inhibitors of EGFRT790M/BRAFV600E Pathways

Mutant EGFR/BRAF pathways are thought to be crucial targets for the development of anticancer drugs since they are over-activated in several malignancies. We present here the development of a novel series of 5-chloro-indole-2-carboxylate 3a-e, 4a-c and pyrrolo[3,4-b]indol-3-ones 5a-c derivatives as potent inhibitors of mutant EGFR/BRAF pathways with antiproliferative activity. The cell viability assay results of 3a-e, 4a-c, and 5a-c revealed that none of the compounds tested were cytotoxic, and that the majority of those tested at 50 µM had cell viability levels greater than 87%. Compounds 3a-e, 4a-c, and 5a-c had significant antiproliferative activity with GI50 values ranging from 29 nM to 78 nM, with 3a-e outperforming 4a-c and 5a-c in their inhibitory actions against the tested cancer cell lines. Compounds 3a-e were tested for EGFR inhibition, with IC50 values ranging from 68 nM to 89 nM. The most potent derivative was found to be the m-piperidinyl derivative 3e (R = m-piperidin-1-yl), with an IC50 value of 68 nM, which was 1.2-fold more potent than erlotinib (IC50 = 80 nM). Interestingly, all the tested compounds 3a-e had higher anti-BRAFV600E activity than the reference erlotinib but were less potent than vemurafenib, with compound 3e having the most potent activity. Moreover, compounds 3b and 3e showed an 8-fold selectivity index toward EGFRT790M protein over wild-type. Additionally, molecular docking of 3a and 3b against BRAFV600E and EGFRT790M enzymes revealed high binding affinity and active site interactions compared to the co-crystalized ligands. The pharmacokinetics properties (ADME) of 3a-e revealed safety and good pharmacokinetic profile.

Pathological MAPK activation-mediated lymphatic basement membrane disruption causes lymphangiectasia that is treatable with ravoxertinib

Lymphangiectasia, an anomalous dilation of lymphatic vessels first described in the 17th century, is frequently associated with chylous effusion, respiratory failure, and high mortality in young patients, yet the underlying molecular pathogenesis and effective treatments remain elusive. Here, we identify an unexpected causal link between MAPK activation and defective development of the lymphatic basement membrane that drives lymphangiectasia. Human pathological tissue samples from patients diagnosed with lymphangiectasia revealed sustained MAPK activation within lymphatic endothelial cells. Endothelial KRASG12D-mediated sustained MAPK activation in newborn mice caused severe pulmonary and intercostal lymphangiectasia, accumulation of chyle in the pleural space, and complete lethality. Pathological activation of MAPK in murine vasculature inhibited the Nfatc1-dependent genetic program required for laminin interactions, collagen crosslinking, and anchoring fibril formation, driving defective development of the lymphatic basement membrane. Treatment with ravoxertinib, a pharmacological inhibitor of MAPK, reverses nuclear-to-cytoplasmic localization of Nfatc1, basement membrane development defects, lymphangiectasia, and chyle accumulation, ultimately improving survival of endothelial KRAS mutant neonatal mice. These results reveal defective lymphatic basement membrane assembly and composition as major causes of thoracic lymphangiectasia and provide a potential treatment.

ALKBH5/MAP3K8 axis regulates PD-L1+ macrophage infiltration and promotes hepatocellular carcinoma progression

Hepatocellular carcinoma is one of the most common malignant tumors.M6A is a novel epigenetic modification that have been emerged as vital regulators for the progression of HCC. However, the regulatory role, clinical significance and the details of the modification, such as the impact on the local tumor environment, remain largely unclear. Our study showed that ALKBH5 was highly expressed in HCC and high ALKBH5 expression predicted a worse prognosis of HCC patients. Prediction of ALKBH5 function by tissue samples and single cell sequencing Gene Set Variation Analysis. Primary CD3 + T lymphocytes and bone marrow-derived macrophages were used to evaluate the effect of ALKBH5 on immune microenvironment. The results indicated that ALKBH5 promote HCC cell proliferation, metastasis and PD-L1+macrophage recruitment. Mechanistically the results showed that ALKBH5 regulates MAP3K8 expression in a m6A dependent manner which mediates the proliferation and metastasis of HCC cells. ALKBH5 also promotes the activation of JNK and ERK pathways through upregulating MAP3K8, thus regulating the expression of IL-8 and promoting macrophage recruitment. Taken together, these data show that ALKBH5 promotes HCC growth, metastasis and macrophage recruitment through ALKBH5/MAP3K8 axis and it may serve as a potential diagnostic marker and target for treatment of HCC patients.

Itraconazole-Induced the Activation of Adenosine 5'-Monophosphate (Amp)-Activated Protein Kinase Inhibits Tumor Growth of Melanoma via Inhibiting ERK Signaling

Itraconazole, an effective broad-spectrum antifungal drug, has been well established for its anticancer activity in cancers including melanoma. However, details concerning its underlying mechanism in melanoma are unclear. This work investigated the function of itraconazole-induced 5'-monophosphate (AMP)-activated protein kinase alpha (AMPKα) in melanoma progression through ERK signaling. The AMPKα level in melanoma tissues and cells was assessed by RT-qPCR and western blot. Survival analysis of patients with melanoma based on the AMPKα expression level was performed according to TCGA database. Melanoma cell proliferation, migration, and invasion were examined using CCK-8, colony formation, wound healing, and Transwell assays. A xenograft tumor model was established to examine the effect of itraconazole on tumor growth in vivo. The AMPKα mRNA and protein levels were reduced in melanoma tissues and cells. A low expression of AMPKα indicated a poor prognosis. Functionally, itraconazole restrained melanoma cell proliferation, migration, and invasion by upregulating AMPKα. Itraconazole activated AMPK signaling and inhibited ERK signaling in melanoma cells. Activation of ERK signaling reversed the effect of itraconazole on cellular process in melanoma. Moreover, itraconazole-induced AMPKα inhibited melanoma tumor growth in vivo by inhibiting ERK signaling. Itraconazole-induced AMPKα inhibits the progression of melanoma by inhibition of ERK signaling.

Molecular target therapeutics of EGF-TKI and downstream signaling pathways in non-small cell lung cancers

Lung carcinoma (LC) is the third most common cancer diagnosis and accounted for the most cancer-related mortality worldwide in 2018. Based on the type of cells from which it originates, LC is commonly classified into non-small cell lung cancers (NSCLC) and small cell lung cancers (SCLC). NSCLC account for the majority of LC and can be further categories into adenocarcinoma, large cell carcinoma, and squamous cell carcinoma. Accurate classification of LC is critical for its adequate treatment and therapeutic outcome. Since NSCLC express more epidermal growth factor receptor (EGFR) with activation mutations, targeted therapy EGFR-tyrosine kinase inhibitors (TKIs) have been considered as primary option of NSCLC patients with activation EGFR mutation. In this review, we present the genetic alterations, reported mutations in EGFR, and TKIs treatment in NSCLC patients with an emphasis on the downstream signaling pathways in NSCLC progression. Among the signaling pathways identified, mitogen activation protein kinase (MAPK), known also as extracellular signal-regulated protein kinase (Erk) pathway, is the most investigated among the related pathways. EGFR activation leads to the autophosphorylation of its kinase domain and subsequent activation of Ras, phosphorylation of Raf and MEK1/2, and the activation of ERK1/2. Phosphatidylinositol 3-kinase (PI3K)/Akt is another signal pathway that regulates cell cycle and has been linked to NSCLC progression. Currently, three generations of EGFR TKIs have been developed as a first-line treatment of NSCLC patients with EGFR activation and mutation in which these treatment options will be further discussed in this review. The Supplementary Appendix for this article is available at http://links.lww.com/JCMA/A138.

Oncogenic circRNA hsa_circ_0000190 modulates EGFR/ERK pathway in promoting NSCLC

Lung cancers (LC) are the leading cause of cancer-related mortality worldwide, and the majority of LC are non-small cell lung carcinoma (NSCLC). Overexpressed or activated EGFR has been associated with a poor prognosis in NSCLC. We previously identified a circular non-coding RNA, hsa_circ_0000190 (C190), as a negative prognostic biomarker of LC. Here we attempted to dissect the mechanistic function of C190 and test the potential of C190 as a therapeutic target in NSCLC. C190 was upregulated in both NSCLC clinical samples and cell lines. Activation of the EGFR pathway increased C190 expression through a MAPK/ERK-dependent mechanism. Transient and stable overexpression of C190 induced ERK1/2 phosphorylation, proliferation, and migration in vitro and xenograft tumor growth in vivo. RNA sequencing and Expression2Kinases (X2K) analysis indicated that kinases associated with cell cycle and global translation are involved in C190-activated networks, including CDKs and p70S6K, which were further validated by immunoblotting. CRISPR/Cas13a-mediated knockdown of C190 decreased proliferation and migration of NSCLC cells in vitro and suppressed tumor growth in vivo. TargetScan and CircInteractome databases predicted that C190 targets CDKs by sponging miR-142-5p. Analysis of clinical LC samples showed that C190, CDK1, and CDK6 expression were significantly higher in advanced-stage LC than in early-stage LC. In summary, C190 is directly involved in EGFR-MAPK-ERK signaling and may serve as a potential therapeutic target for the treatment of NSCLC.

Structure based designing of thiazolidinone-pyrimidine derivatives as ERK2 inhibitors: Synthesis and in vitro evaluation

Breast cancer has been associated with an overexpression of various molecular targets; accordingly, various target-specific chemotherapeutic agents have been developed. Inhibition of ERK2, a member of MAPK pathway, is an important target involved in the treatment of both oestrogen receptor-positive and triple-negative breast cancer. Thus, in continuation of our previous work on the ERK2 target, we here report novel inhibitors of this kinase. Out of three lead molecules reported in our previous study, we selected the thiazolidinone-pyrimidine scaffold for further development of small molecule inhibitors of ERK2. Analogues of the lead molecule were docked in the target kinase, followed by molecular dynamic simulations and MM-GBSA calculations. Analogues maintaining key interactions with amino acid residues in the ATP-binding domain of ERK2 were selected and duly synthesized. In vitro biochemical evaluation of these molecules against ERK2 kinase disclosed that two molecules possess significant kinase inhibitory potential with IC₅₀ values ≤ 0.5 µM.

Elucidation of Abnormal Extracellular Regulated Kinase (ERK) Signaling and Associations with Syndromic and Non-syndromic Autism

Autism is a highly inherited and extremely complex disorder in which results from various cases indicate chromosome anomalies, unusual single-gene mutations, and multiplicative effects of particular gene variants, characterized primarily by impaired speech and social interaction and restricted behavior. The precise etiology of Autism Spectrum Disorder (ASD) is currently unclear. The extracellular signal-regulated kinase (ERK) signaling mechanism affects neurogenesis and neuronal plasticity during the development of the central nervous mechanism. In this regard, the pathway of ERK has recently gained significant interest in the pathogenesis of ASD. The mutation occurs in a few ERK components. Besides, the ERK pathway dysfunction lies in the upstream of modified translation and contributes to synapse pathology in syndromic types of autism. In this review, we highlight the ERK pathway as a target for neurodevelopmental disorder autism. In addition, we summarize the regulation of the ERK pathway with ERK inhibitors in neurological disorders. In conclusion, a better understanding of the ERK signaling pathway provides a range of therapeutic options for autism spectrum disorder.

RAF-MEK-ERK pathway in cancer evolution and treatment

The RAF-MEK-ERK signaling cascade is a well-characterized MAPK pathway involved in cell proliferation and survival. The three-layered MAPK signaling cascade is initiated upon RTK and RAS activation. Three RAF isoforms ARAF, BRAF and CRAF, and their downstream MEK1/2 and ERK1/2 kinases constitute a coherently orchestrated signaling module that directs a range of physiological functions. Genetic alterations in this pathway are among the most prevalent in human cancers, which consist of numerous hot-spot mutations such as BRAF^V600E. Oncogenic mutations in this pathway often override otherwise tightly regulated checkpoints to open the door for uncontrolled cell growth and neoplasia. The crosstalk between the RAF-MEK-ERK axis and other signaling pathways further extends the proliferative potential of this pathway in human cancers. In this review, we summarize the molecular architecture and physiological functions of the RAF-MEK-ERK pathway with emphasis on its dysregulations in human cancers, as well as the efforts made to target the RAF-MEK-ERK module using small molecule inhibitors.

PBK/TOPK: An Effective Drug Target with Diverse Therapeutic Potential

Simple Summary

Cancer is a major public health problem worldwide, and addressing its morbidity, mortality, and prevalence is the first step towards appropriate control measures. Over the past several decades, many pharmacologists have worked to identify anti-cancer targets and drug development strategies. Within this timeframe, many natural compounds have been developed to inhibit cancer growth by targeting kinases, such as AKT, AURKA, and TOPK. Kinase assays and computer modeling are considered to be effective and powerful tools for target screening, as they can predict physical interactions between small molecules and their bio-molecular targets. In the present review, we summarize the inhibitors and compounds that target TOPK and describe its role in cancer progression. The extensive body of research that has investigated the contribution of TOPK to cancer suggests that it may be a promising target for cancer therapy.

Abstract

T-lymphokine-activated killer cell-originated protein kinase (TOPK, also known as PDZ-binding kinase or PBK) plays a crucial role in cell cycle regulation and mitotic progression. Abnormal overexpression or activation of TOPK has been observed in many cancers, including colorectal cancer, triple-negative breast cancer, and melanoma, and it is associated with increased development, dissemination, and poor clinical outcomes and prognosis in cancer. Moreover, TOPK phosphorylates p38, JNK, ERK, and AKT, which are involved in many cellular functions, and participates in the activation of multiple signaling pathways related to MAPK, PI3K/PTEN/AKT, and NOTCH1; thus, the direct or indirect interactions of TOPK make it a highly attractive yet elusive target for cancer therapy. Small molecule inhibitors targeting TOPK have shown great therapeutic potential in the treatment of cancer both in vitro and in vivo, even in combination with chemotherapy or radiotherapy. Therefore, targeting TOPK could be an important approach for cancer prevention and therapy. Thus, the purpose of the present review was to consider and analyze the role of TOPK as a drug target in cancer therapy and describe the recent findings related to its role in tumor development. Moreover, this review provides an overview of the current progress in the discovery and development of TOPK inhibitors, considering future clinical applications.

New bioactive 5-arylcarboximidamidopyrazolo[3,4-c]pyridines: Synthesis, cytotoxic activity, mechanistic investigation and structure-activity relationships

In this study, a series of novel substituted pyrazolo[3,4-c]pyridin-5-ylamidines was synthesized and their cytotoxicity against three cancer cell lines (MDA-MB-231, HT-1080, PC-3), as well as a human normal cell line (AG01523) was evaluated. A number of derivatives could strongly reduce cancer cells proliferation and exhibit apoptotic induction capability, while reasonable structure-activity relationships could be extracted. Certain analogues were endowed with low toxicity against normal cells. Cell cycle analysis revealed that most of the active compounds induced a G₀/G₁ arrest of HT-1080 cells. Moreover, the potential mechanisms of the cytotoxic activity of the promising compounds were investigated in HT-1080 cells, upon study of their effects on the phosphorylation of Akt, ERK and p38 MAPK. Most of the active derivatives inhibit phosphorylation of Akt and ERK and/or induce p38 MAPK phosphorylation, providing a potential indication on the mode of action of this class.

GINS2 affects cell proliferation, apoptosis, migration and invasion in thyroid cancer via regulating MAPK signaling pathway

Globally, thyroid cancer (TC) is considered to be the commonest endocrine malignancy. GINS complex subunit 2 (GINS2) belongs to the GINS complex family and is associated with cellular migration, invasion and growth. The present study aimed to investigate the underlying mechanisms of GINS2 on cell viability, migration and invasion in TC cells. By using MTT, wound healing and Transwell assays, the cell viability, migration and invasion were determined. Apoptosis was examined by immunofluorescence. Western blotting was used to detect protein expression levels. In the present study, biological function analysis demonstrated that GINS2 interference attenuated cell viability, migration and invasion in TC cell lines (K1 and SW579). It was discovered that, compared with the control group, GINS2 silencing induced apoptosis in TC cells. Additionally, GINS2 interference inhibited key proteins in the MAPK signaling pathway, including JNK, ERK and p38. According to these comparative experiments, GINS2 was considered to act a pivotal part in cell viability, migration and invasion of TC by regulating the MAPK signaling pathway and might be a potential therapeutic target for treating TC.

HER2 Signaling in Breast Cancer

HER2 gene amplification occurs in many breast cancer patients and is associated with poor clinical prognosis. Trastuzumab is a therapeutic monoclonal antibody binding to HER2 and inhibits growth of HER2-positive breast cancer cells and used as a principal treatment for HER2-positive breast cancer. Unfortunately, some HER2-positive breast cancers eventually relapse after trastuzumab treatment. To investigate the molecular mechanism of trastuzumab resistance, we generated trastuzumab-resistant cells using a mouse model and found ECM1 protein is increased in trastuzumab-resistant cells. ECM1 was shown to increase EGFR signaling via upregulated matrix metalloproteinase 9/galectin-3/mucin pathway. To further find the novel mediators of HER2-driven signaling pathways in breast cancer, we investigated the upregulated proteins in HER2-overexpressing breast cancer cells using a proteomics approach and found that KRT19 is strongly upregulated in HER2-positive breast cancer cells and it activates HER2 signaling by binding to HER2 and stabilizes the receptor on the cell membrane. Moreover, we found that treatment of KRT19 antibody resulted in reduced cell viability of trastuzumab-resistant HER2-positive breast cancer cells as well as trastuzumab-sensitive cancer cells both in vitro and in vivo.

A novel dual MEK/PDK1 inhibitor 9za retards the cell cycle at G0/G1 phase and induces mitochondrial apoptosis in non-small cell lung cancer cells

Background

A novel dual MEK/PDK1 inhibitor named 9za has been synthesized by our research team. Preliminary study showed that 9za possessed potent cytotoxicity and proapoptosis in non-small cell lung cancer (NSCLC) cells. Nevertheless, the precise underlying mechanism is vague.

Methods

In this work, we adopted the MTT assay, the Cell Cycle Detection Kit, and the JC-1 staining assay to detect the cell viability, the cell cycle distribution and the mitochondrial membrane potential (MMP), respectively. Cell apoptosis was measured by the morphology observation under a light microscope, Annexin V-FITC/propidium iodide (PI) apoptosis detection and the colorimetric TUNEL assay. Western blot was used to monitor the cell cycle-, apoptosis-related proteins and relevant proteins involved in the signaling pathways.

Results

The MTT assay demonstrated that 9za sharply decreased the viability of NSCLC cells. Cell cycle analysis revealed that low concentrations of 9za arrested the cell cycle at the G₀/G₁ phase , which was further confirmed by the decreased levels of Cyclin D1, cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6). Additionally, morphological observations, Annexin V-FITC/propidium iodide (PI) apoptosis analysis and TUNEL assays indicated that high concentrations of 9za induced cell apoptosis. Furthermore, the JC-1 staining assay revealed that the mitochondrial membrane potential was downregulated following 9za exposure. Western blot also showed that 9za markedly decreased the expression levels of total Bcl-2, Cytochrome C in the mitochondria and BCL2 associated X (BAX) in the cytoplasm. However, the levels of BAX in the mitochondria, Cytochrome C in the cytoplasm, active caspase-9, active caspase-3 and cleaved–PARP showed the opposite changes. Moreover, the dose-dependent decreased phosphorylation levels of PDK1, protein kinase B (Akt), MEK and extracellular signal regulated kinase 1/2 (ERK1/2) after 9za treatment verified that 9za was indeed a dual MEK/PDK1 inhibitor, as we expected. Compared with a single MEK inhibitor PD0325901 or a single PDK1 inhibitor BX517, the dual MEK/PDK1 inhibitor 9za could strengthen the cytotoxic and proapoptotic effect, indicating that the double blocking of the MEK and PDK1 signaling pathways plays stronger cell growth inhibition and apoptosis induction roles than the single blocking of the MEK or PDK1 signaling pathway in NSCLC cells. Our work elucidated the molecular mechanisms for 9za as a novel drug candidate against NSCLC.

LncRNA HOTTIP promotes the proliferation and invasion of ovarian cancer cells by activating the MEK/ERK pathway

Recent studies have revealed that long non-coding RNAs (lncRNAs) serve important roles in carcinogenesis and that this type of gene may be used as biomarkers in cancer. A high level of lncRNA HOXA distal transcript antisense RNA (HOTTIP) is associated with unfavorable prognosis for patients with ovarian cancer (OC), but the mechanism of HOTTIP involved in OC development remains to be elucidated. The present study aimed to investigate the mechanism of HOTTIP in metastasis-associated OC cell behaviors. HOTTIP levels in ovarian cells were quantified by reverse transcription-quantitative PCR, cell proliferation was analyzed by colony formation assay, and apoptosis was assessed by flow cytometry. Cell migratory and invasive abilities were evaluated by wound healing and Transwell assays, respectively. The expression levels of mitogen-activated protein kinase kinase (MEK)/ERK pathway-associated proteins were detected by western blotting. The results demonstrated that knockdown of HOTTIP in OC cells significantly reduced the phosphorylation levels of MEK and ERK, inhibited the proliferation and invasion of OC cells and promoted their apoptosis. Furthermore, the effects of HOTTIP on cell migration and invasion were partly associated with the epithelial-mesenchymal transition (EMT) process. Proliferation, invasion and EMT of OC cells were enhanced following overexpression of HOTTIP; however, these effects were reversed by the MEK/ERK pathway inhibitor U0126. In conclusion, HOTTIP was demonstrated to promote the proliferation, migration and invasion of OC cells by activating the MEK/ERK pathway. Therefore, HOTTIP may serve as a potential therapeutic target for OC.

Historical retrospective of the oncogene and new perspectives (Review)

Since its first discovery as part of the Rous sarcoma virus (RSV) genome, the c-SRC (SRC) proto-oncogene has been proved a key regulator of cancer development and progression, and thus it has been highlighted as an attractive target for anti-cancer therapeutic strategies. Though the exact mechanisms of its action are still not fully understood, SRC protein mediates crucial normal cell functions, such as cell development, proliferation and survival, and its dysregulation is considered as an oncogenic signature and a driving force for cancer initiation. In the present review, we present a flashback to the history of the Src research, while focusing on the most important milestones in the field. Moreover, we investigate the proposed regulatory mechanisms and molecules that mediate its action in order to designate putative therapeutic targets and useful prognostic and/or diagnostic tools. Furthermore, we present and discuss existing therapeutic approaches that are explored in clinical settings.

Enhanced anti-hepatoma effect of a novel curcumin analog C086 via solid dispersion technology

The novel curcumin analog C086, previously identified as an oral novel heat shock protein 90 (Hsp90) inhibitor, was found to exhibit anti-hepatoma activity in vitro and in vivo. However, owing to its limited aqueous solubility, the usage of C086 in the clinical application was restricted. This research focused on the increase of the aqueous solubility and bioavailability of C086 via a solid dispersion preparation to improve its accumulation in the liver, which accordingly enhanced anti-hepatoma activity. C086-solid dispersion (C086-SD) was successfully prepared by using solvent evaporation technology. As compared with bulk compound, aqueous solubility obtained with the optimal formulation (C086/PVP k30:1/6 (w/w)) was increased by 1.741 million-fold, and in the following oral administration experiment, bioavailability was found to be improved by an approximately 28-fold relative to C086-Suspension and accumulate preferably in the liver. Accordingly, C086-SD exhibited stronger potent anti-proliferative effects against liver cancer cell line (i.e. HepG2) than pure C086. Moreover, C086-SD was found to have an enhanced anti-hepatoma effect using the orthotopic hepatocellular carcinoma xenograft in BALB/C nude mice. The results above suggested the potential application of C086-SD in the treatment of liver cancer.

Dual Inhibition of MAPK and JAK2/STAT3 Pathways Is Critical for the Treatment of BRAF Mutant Melanoma

BRAF and MEK inhibitors significantly prolong progression-free survival in patients with BRAF mutant melanoma. However, most patients quickly develop drug resistance. The mechanism of drug resistance is complicated and remains to be further explored. Here, we found that inhibition of the MAPK pathway activates the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway, whereas JAK2 inhibitors that inhibit the JAK2/STAT3 pathway activate the MAPK pathway, suggesting a crosstalk between these two pathways in BRAF mutant melanoma cells. Reactivation of the MAPK pathway occurs in most drug-resistant patients with BRAF mutations. Therefore, dual inhibition of the MAPK and JAK2/STAT3 pathways is critical for the treatment of BRAF mutant melanoma. However, we found that the combination of BRAF, MEK inhibitors, and JAK2 or STAT3 inhibitors could not simultaneously inhibit the MAPK and JAK2/STAT3 pathways in BRAF mutant melanoma cells. Subsequently, we found that a combination of all three MAPK pathway inhibitors—BRAF, MEK, and ERK inhibitors—with JAK2 or STAT3 inhibitors can dually inhibit the MAPK and JAK2/STAT3 pathways, showing a significant inhibition of the growth of BRAF mutant melanoma cells compared with either treatment alone. Therefore, dual inhibition of MAPK and JAK2/STAT3 pathways may be a novel strategy for the treatment of BRAF mutant tumors.

GINS2 affects cell viability, cell apoptosis, and cell cycle progression of pancreatic cancer cells via MAPK/ERK pathway

Background and Objective: GINS complex subunit 2 (GINS2), a member of the GINS complex, is involved in DNA replication. GINS2 is upregulated in a variety of aggressive tumors, such as leukemia, breast cancer, and cervical cancer. However, the role of GINS2 in pancreatic cancer has still remained elusive. In this study, PANC-1 and BxPC-3 cell lines were chosen to perform experiments in vitro. Additionally, the effects of GINS2 interference on the cell viability, cell apoptosis, cell cycle, and tumor growth in nude mice were analyzed.

Methods: We utilized pancreatic cancer cell lines that knocked down GINS2 expression using small interference RNA (siRNA) and evaluated GINS2 expression using Western blot analysis. To explore the function of GINS2 in pancreatic cancer cell lines in vitro, MTT assay and flow cytometry were used. Additionally, we investigated the potential mechanism of GINS2 interference by identifying the MAPK/ERK pathway using Western blotting. Finally, PANC-1 cells with GINS2 knockdown were subcutaneously injected into nude mice to evaluate the effects of GINS2 on tumor growth in vivo.

Results: It was unveiled that GINS2 interference inhibited cell viability, induced cell cycle arrest at G1 phase, and enhanced apoptosis of pancreatic cancer cell lines. Western blot assay indicated that GINS2 interference increased the expression level of Bax, while the expression level of Bcl-2 was remarkably decreased. In addition, the expression levels of CDK4, CDK6, and Cyclin D1 were significantly reduced after treatment with GINS2 siRNA. Furthermore, GINS2 interference drastically attenuated the expression levels of MEK, p-MEK, ERK, and p-ERK, belonging to the MAPK/ERK pathway. The results of an established cancer xenograft model revealed that nude mice transplanted with cells expressing negative control (NC) exhibited larger and heavier tumors, while volume and weight of tumor were remarkably reduced in ones transplanted with cells expressing GINS2 siRNA.

Conclusions: GINS2 interference inhibited cell viability, induced cell cycle arrest, and promoted cell apoptosis of pancreatic cancer cell lines via the MAPK/ERK pathway, and our findings may be valuable for treating pancreatic cancer.

The Analysis of the Anti-Tumor Mechanism of Ursolic Acid Using Connectively Map Approach in Breast Cancer Cells Line MCF-7

BACKGROUND

Ursolic acid (UA), a primary bioactive triterpenoid, was reported as an anti-cancer agent. However, the current knowledge of UA and its potential anti-cancer mechanisms and targets in breast cancer cells are limited. In this study, we aimed to illustrate the potential mechanisms and targets of UA in breast cancer cells MCF-7.

METHODS

The effect of UA on cell growth was determined in MCF-7 cells by MTT assay. The anti-tumor mechanism of UA was evaluated by microarray, CAMP, and Western blot. Moreover, the molecular docking between UA and potential receptors were predicted by iGEMDOCK software.

RESULTS

The result of MTT assay demonstrated that UA could inhibit MCF-7 cell growth with IC50 values of 20 μM. Microarray and CMAP analysis, validated by Western blot, indicated that UA significantly modulated IKK/NF-κB, RAF/ERK pathways, and down-regulated the phosphorylation level of PLK1 in MCF-7 cells.

CONCLUSION

Our data indicated that the anti-tumor effects of UA are due to the inhibited RAF/ERK pathway and IKK/NF-κB pathway. It could also be explained by the reduced phosphorylation of PLK1 in MCF-7 cells. This study provides a new insight for deep understanding of the new anti-cancer mechanisms of UA in MCF-7 breast cancer cells.

An update on chemical classes targeting ERK1/2 for the management of cancer

Cancer, still in the limelight due to its dreadful nature, shows overexpression of multiple signaling macromolecules leading to failure of many chemotherapeutic agents and acquired resistance to chemotherapy. These factors highlight the significance of shifting toward targeted therapy in cancer research. Recently, ERKs (ERK1 and 2) have been established as a promising target for the management of various types of solid tumors, due to their aberrant involvement in cell growth and progression. Several ERKs inhibitors have reached clinical trials for the management of cancer and their derivatives are being continuously reported with noteworthy anticancer effect. This review highlights the recent reports on various chemical classes involved in the development of ERKs inhibitors along with their in vitro and in vivo activity and structure-activity relationship profile.

MUC15 promotes growth and invasion of glioma cells by activating Raf/MEK/ERK pathway

MUC15 is a novel mucin associated with the cell membrane that is overexpressed in human gliomas. Its function in glioma is unclear. In this study, high MUC15 levels were detected in glioma tissues and cells. We found that transfection with MUC15 siRNA in U251 and T98G cells reduced MUC15 expression and decreased cell proliferation, invasion, and migration (P < .05). After transfecting U251 and T98G cells with pcDNA3.1-myc-His-MUC15 plasmid to overexpress MUC15, MUC15 expression was significantly upregulated and cell proliferation, invasion, and migration were increased (P < .05). MUC15 activated the Raf/MEK/ERK signalling pathway and the ERK inhibitor PD98059 partly reversed MUC15-enhanced proliferation, invasion, and migration of glioma cells (P < .05). The results indicate that MUC15 plays a part in glioma tumorigenesis, and the Raf/MEK/ERK signalling is involved in the regulation of MUC15 on glioma cell activity.

MicroRNA-665 promotes the proliferation of ovarian cancer cells by targeting SRCIN1

Recent studies have discovered several microRNAs (miRNAs/miRs) as biomarkers for the prediction of ovarian cancer by detecting miRNA profiles in serum samples from healthy volunteers and patients with ovarian cancer. However, whether and how these miRNAs are involved in tumorigenesis is not known. In the present study, the expression of miR-665, a recently discovered biomarker for ovarian cancer, was upregulated in tumor tissues from patients with ovarian cancer compared with normal tissues. Inhibition of miR-665 inhibited cell proliferation ability and inactivated MAPK/ERK signaling of ovarian cancer cells. Using bioinformatics analysis, Src kinase signaling inhibitor 1 (SRCIN1) was predicted as a potential target gene of miR-665. Reverse transcription-quantitative PCR and western blotting showed that SRCIN1 expression was repressed by miR-665 in ovarian cancer cells. In addition, a dual luciferase activity assay showed that SRCIN1 was a target gene of miR-665. Silencing of SRCIN1 could reverse the cell growth arrest, which was induced by the miR-665 inhibitor. Moreover, miR-665 levels were negatively correlated with SRCIN1 mRNA levels in tumor tissues from patients with ovarian cancer. In conclusion, the present data suggested that miR-665 functioned as an oncogene in ovarian cancer by directly repressing the expression of SRCIN1.

Apoptotic SKOV3 cells stimulate M0 macrophages to differentiate into M2 macrophages and promote the proliferation and migration of ovarian cancer cells by activating the ERK signaling pathway

Ovarian cancer has a high rate of recurrence, with M2 macrophages having been found to be involved in its progression and metastasis. To examine the relationship between macrophages and ovarian cancer in the present study, M0 macrophages were stimulated with apoptotic SKOV3 cells and it was found that these macrophages promoted tumor proliferation and migration. Subsequently, the mRNAs and proteins expressed at high levels in these M2 macrophages were examined by RNA-Seq and quantitative proteomics, respectively, which revealed that M0 macrophages stimulated by apoptotic SKOV3 cells also expressed M2 markers, including CD206, interleukin-10, C-C motif chemokine ligand 22, aminopeptidase-N, disabled homolog 2, matrix metalloproteinase 1 and 5′-nucleotidase. The abundance of phosphorylated Erk1/2 in these macrophages was increased. The results indicate that apoptotic SKOV3 cells stimulate M0 macrophages to differentiate into M2 macrophages by activating the ERK pathway. These results suggest possible treatments for patients with ovarian cancer who undergo chemotherapy; inhibiting M2 macrophage differentiation during chemotherapy may reduce the rate of tumor recurrence.

BZW2 promotes the malignant progression of colorectal cancer via activating the ERK/MAPK pathway

Colorectal cancer (CRC) is one of the most prevalent malignant solid cancers worldwide involving the dysregulation of multiple signaling molecules. However, the role and corresponding mechanism of basic leucine zipper and W2 domains 2 (BZW2) in CRC development, to our knowledge, has not been reported. We found BZW2 was overexpressed in human CRC tissues compared with that in paired adjacent colorectal samples. BZW2 overexpression was closely associated with tumor T stage (p = .030), metastatic lymph nodes (p = .037), TNM stage (p = .018) and the worse prognosis of CRC patients (p = .009). Moreover, BZW2 was an independent disadvantage prognostic factor (p = .031). BZW2 also showed an increased expression in different invasive CRC cell lines. Its silencing and overexpression diminished and increased cell proliferation, invasion, and migration in Colo205 and HCT116 cells via specifically activating of extracellular-signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling. Moreover, ERK/MAPK inhibitor PD98059 reverse the enhancement of cell proliferation, invasion, and migration in BZW2 overexpressing HCT116 cells. BZW2 silencing also inhibited subcutaneous tumors growth and p-ERK expression in vivo. BZW2 promotes the malignant progression of CRC via activating ERK/MAPK signaling, which provided a promising gene target therapy for CRC.

The crucial role of ZEB2: From development to epithelial-to-mesenchymal transition and cancer complexity

Zinc finger E-box binding homeobox 2 (ZEB2) is a DNA-binding transcription factor, which is mainly involved in epithelial-to-mesenchymal transition (EMT). EMT is a conserved process during which mature and adherent epithelial-like state is converted into a mobile mesenchymal state. Emerging data indicate that ZEB2 plays a pivotal role in EMT-induced processes such as development, differentiation, and malignant mechanisms, for example, drug resistance, cancer stem cell-like traits, apoptosis, survival, cell cycle arrest, tumor recurrence, and metastasis. In this regard, the understanding of mentioned subjects in the development of normal and cancerous cells could be helpful in cancer complexity of diagnosis and therapy. In this study, we review recent findings about the biological properties of ZEB2 in healthy and cancerous states to find new approaches for cancer treatment.

ANO6 promotes cell proliferation and invasion in glioma through regulating the ERK signaling pathway

Purpose

Anoctamin6 (ANO6) plays a crucial role in several cancers, whereas the specific role of ANO6 in glioblastoma is unclear.

Methods

Kaplan-Meier survival analysis was used to analysis the correlation between ANO6 and survival rate of patients with glioblastoma. Univariate Cox regression analysis was used to analysis the correlation among ANO6 expression level,and age, gender, WHO and overall survival rate. Immunohistocemical technique, RT-PCR and western blot were used to dected the ANO6 expression. CCK8, colony formation and transwell were used to detected cell viability, cell proliferation and cell invasion in glioblastoma cells transfected with sh-ANO6 and ANO6 overexpression. In addition, after SHG-44 cells trasfected with ANO6 overexpression were ERK inhibitor (PD98059), CCK8, colony formation and transwell were used to detected cell viability, cell proliferation and cell invasion. Western blot was used to detected ERK protein level and the phosphorylation level of ERK in T89G and U87MG cells tranfected wih sh-ANO6.

Results

The results indicated that the ANO6 expression level was significantly associated with patients' age and tumor stage. Univariate Cox regression analysis showed that the ANO6 expression level, age, gender and tumor stage were not related to the overall survival rate. ANO6 inhibition significantly suppressed the viability, invasion and the ability of colony formation in glioma cells, while ANO6 overexpression led to the opposite results in SHG-44 cells. ANO6 knockdown strongly inhibits the phosphorylation level and nuclear translocation of extracellular signal-regulated kinase (ERK) protein to inhibit ERK signaling. ERK inhibitor significantly decreased the cell proliferation and invasion in SHG-44 cells transfected with sh-ANO6.

Conclusion

This study revealed that ANO6 activited ERK signaling pathway through promoting the nuclear translocation of ERK to increase the proliferation and invasion of glioblastoma cells.

Development of ERK1/2 inhibitors as a therapeutic strategy for tumour with MAPK upstream target mutations

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) phosphorylate a variety of substrates that play key roles in promoting cell survival and proliferation. Many inhibitors, acting on upstream of the ERK pathway, exhibit excellent antitumor activity. However, drug-resistant tumour cells invariably emerge after their use due to the reactivation of ERK1/2 signalling. ERK1/2 inhibitors have shown clinical efficacy as a therapeutic strategy for the treatment of tumours with mitogen-activated protein kinase (MAPK) upstream target mutations. These inhibitors may be effective against cancers with altered MAPK upstream pathway and may be used as a possible strategy to overcome acquired resistance to MAPK inhibitors. In this review, we describe the mechanism and types of ERK1/2 inhibitors, summarise the current development status of small-molecule ERK1/2 inhibitors, including the preclinical data and clinical study progress, and discuss the future research directions for the application of ERK1/2 inhibitors.

Selective activation of tumor-suppressive MAPKP signaling pathway by triptonide effectively inhibits pancreatic cancer cell tumorigenicity and tumor growth

The mitogen-activated protein kinase (MAPK, 1K) family members ERK, JNK, and p38 play a divergent role in either promoting tumorigenesis or tumor-suppression. Activation of ERK and JNK promotes tumorigenesis; whereas, escalation of p38 inhibits carcinogenesis. As these three MAPK members are controlled by the common up-stream MAPK signaling proteins which consist of MAPK kinases (2K) and MAPK kinase kinases (3K), how to selectively actuate tumor-suppressive p38, not concurrently stimulate tumorigenic ERK and JNK, in cancer cells is a challenge for cancer researchers, and a new opportunity for novel anti-cancer drug discovery. Using human pancreatic cancer cells and xenograft mice as models, we found that a small molecule triptonide first discerningly activated the up-stream MAPK kinase kinase MEKK4, not the other two 3K members ASK1 and GADD45; and then selectively actuated the middle stream MAPK kinase MKK4, not the other two 2K members MKK3 and MKK6; and followed by activation of the MAPK member p38, not the other two members ERK and JNK. These data suggest that triptonide is a selective MEKK4-MKK4-p38 axis agonist. Consequently, selective activation of the MEKK4-MKK4-p38 signaling axis by triptonide activated tumor suppressor p21 and inhibited CDK3 expression, resulting in cancer cell cycle arrest at G2/M phase and marked inhibition of pancreatic cancer cell tumorigenic capability in vitro and tumor growth in xenograft mice. Our findings support the notion that selective activation of tumor-suppressive MEKK4-MKK4-p38-p21signaling pathway by triptonide is a new approach for pancreatic cancer therapy, providing a new drug candidate for development of novel anti-cancer therapeutics.

The antitumor effect of hinesol, extract from Atractylodes lancea (Thunb.) DC. by proliferation, inhibition, and apoptosis induction via MEK/ERK and NF-κB pathway in non-small cell lung cancer cell lines A549 and NCI-H1299

Lung cancer (especially, non-small cell lung cancer [NSCLC]) is one of the most malignant cancers in the world. Hinesol is the major component of the essential oil of Atractylodes lancea (Thunb.) DC and possesses the most promising anticancer function. However, the effects and molecular mechanism of hinesol on antiproliferation in NSCLC cells has not been well understood. In this study, we found that hinesol effectively inhibited the A549 and NCI-H1299 cells in a dose- and time-dependent manner by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay. In addition, hinesol induced cell cycle arrest at G0/G1 phase and apoptosis assessed by flow cytometry in A549 cells. Furthermore, Western blot analysis showed that hinesol decreased phosphorylation of mitogen-activated protein kinase, extracellular signal-regulated kinase, IκBα, and p65 inhibited the expressions of Bcl-2, cyclin D1 and upregulated the expression of Bax. Based on these results, hinesol might be a potential drug candidate of anti-NSCLC for therapy.

Helping the Released Guardian: Drug Combinations for Supporting the Anticancer Activity of HDM2 (MDM2) Antagonists

The protein p53, known as the "Guardian of the Genome", plays an important role in maintaining DNA integrity, providing protection against cancer-promoting mutations. Dysfunction of p53 is observed in almost every cancer, with 50% of cases bearing loss-of-function mutations/deletions in the TP53 gene. In the remaining 50% of cases the overexpression of HDM2 (mouse double minute 2, human homolog) protein, which is a natural inhibitor of p53, is the most common way of keeping p53 inactive. Disruption of HDM2-p53 interaction with the use of HDM2 antagonists leads to the release of p53 and expression of its target genes, engaged in the induction of cell cycle arrest, DNA repair, senescence, and apoptosis. The induction of apoptosis, however, is restricted to only a handful of p53wt cells, and, generally, cancer cells treated with HDM2 antagonists are not efficiently eliminated. For this reason, HDM2 antagonists were tested in combinations with multiple other therapeutics in a search for synergy that would enhance the cancer eradication. This manuscript aims at reviewing the recent progress in developing strategies of combined cancer treatment with the use of HDM2 antagonists.

Therapeutic gene regulation using pyrrole-imidazole polyamides

Recent innovations in cutting-edge sequencing platforms have allowed the rapid identification of genes associated with communicable, noncommunicable and rare diseases. Exploitation of this collected biological information has facilitated the development of nonviral gene therapy strategies and the design of several proteins capable of editing specific DNA sequences for disease control. Small molecule-based targeted therapeutic approaches have gained increasing attention because of their suggested clinical benefits, ease of control and lower costs. Pyrrole-imidazole polyamides (PIPs) are a major class of DNA minor groove-binding small molecules that can be predesigned to recognize specific DNA sequences. This programmability of PIPs allows the on-demand design of artificial genetic switches and fluorescent probes. In this review, we detail the progress in the development of PIP-based designer ligands and their prospects as advanced DNA-based small-molecule drugs for therapeutic gene modulation.

Unravelling the Role of MAPKs (ERK1/2) in Venous Reflux in Patients with Chronic Venous Disorder

Chronic venous disorder (CVeD), is a disorder in which there is a modification in the conditions of blood return to the heart. The disorder may arise from incompetent valves and the resultant venous reflux (chronic venous insufficiency, CVI). The economic burden of CVeD on health systems is high, and research efforts have sought to elucidate the mechanisms involved as possible therapeutic targets. The mitogen-activated protein kinase (MAPK) enzymes mediate a wide array of physiopathological processes in human tissues. In this family of proteins, extracellular signal-regulated kinase (ERK)1/2 plays a direct role in the cell homeostasis that determines the viability of mammalian tissues. This study sought to examine whether ERK1/2 plays a role in venous reflux. This was a prospective study performed on 56 participants including 11 healthy controls. Of the CVeD patients, 23 had venous reflux with CVI (CVI-R) and 22 had no reflux (NR). Distribution by age was: controls <50 years (n = 4) and ≥50 years (n = 7); NR <50 years (n = 9) and ≥50 years (n = 13); CVI-R <50 years (n = 11) and ≥50 years (n = 12). Great saphenous vein specimens were subjected to gene (real-time polymerase chain reaction, RT-qPCR) and protein (immunohistochemistry, IHC) expression techniques to identify ERK1/2. Data was compared between groups using the Mann Whitney U test. Patients with CVI showed significant gene activation of ERK1/2 protein, and, in those with venous reflux, the expression of this gene was significantly greater. The CVI-R group <50 years showed significantly greater ERK1/2 gene expression than their age-matched controls. Expression patterns were consistent with IHC findings. Our studies suggest that ERK1/2 expression is involved in venous vascular disease.

Dual inhibitors of RAF-MEK-ERK and PI3K-PDK1-AKT pathways: Design, synthesis and preliminary anticancer activity studies of 3-substituted-5-(phenylamino) indolone derivatives

The dysfunction and mutual compensatory activation of RAF-MEK-ERK and PI3K-PDK1-AKT pathways have been demonstrated as the hallmarks in several primary and recurrent cancers. The strategy of concurrent blocking of these two pathways shows clinical merits on effective cancer therapy, such as combinatory treatments and dual-pathway inhibitors. Herein, we report a novel prototype of dual-pathway inhibitors by means of merging the core structural scaffolds of a MEK1 inhibitor and a PDK1 inhibitor. A library of 43 compounds that categorized into three series (Series I-III) was synthesized and tested for antitumor activity in lung cancer cells. The results from structure-activity relationship (SAR) analysis showed the following order of antitumor activity that 3-hydroxy-5-(phenylamino) indolone (Series III) > 3-alkenyl-5-(phenylamino) indolone (Series I) > 3-alkyl-5-(phenylamino) indolone (Series II). A lead compound 9za in Series III showed most potent antitumor activity with IC₅₀ value of 1.8 ± 0.8 µM in A549 cells. Moreover, antitumor mechanism study demonstrated that 9za exerted significant apoptotic effect, and cellular signal pathway analysis revealed the potent blockage of phosphorylation levels of ERK and AKT in RAF-MEK-ERK and PI3K-PDK1-AKT pathways, respectively. The results reported here provide robust experimental basis for the discovery and optimization of dual pathway agents for anti-lung cancer therapy.

miR-330-5p targets SPRY2 to promote hepatocellular carcinoma progression via MAPK/ERK signaling

MicroRNAs (miRNAs) have been identified as critical modulators of cell proliferation and growth, which are the major causes of cancer progression including hepatocellular carcinoma (HCC). Our previous miRNA microarray data have shown that miR-330-5p was always upregulated in HCC. However, the accurate role of miR-330-5p in HCC is still uncertain. Here, we report that miR-330-5p expression is upregulated in HCC tissues and cell lines, and is associated with tumor size, tumor nodule number, capsule formation and Tumor Node Metastasis (TNM) stage in HCC patients. Overexpression of miR-330-5p promotes proliferation and growth of HCC cells in vitro and in vivo, while miR-330-5p knockdown has the inverse effect. Moreover, using miRNA databases and dual luciferase report assay, we find miR-330-5p directly binds to the 3′-untranslated region (3′-UTR) of Sprouty2 (SPRY2). Then we find the novel biofunctional role of SPRY2 inactivation in promoting HCC progression. Finally, we confirm that miR-330-5p suppresses SPRY2 to promote proliferation via mitogen-activated protein kinases (MAPK)/extracellular regulated kinase (ERK) signaling in HCC. Taken together, our findings demonstrate the critical role of miR-330-5p in promoting HCC progression via targeting SPRY2 to activate MAPK/ERK signaling, which may provide a novel and promising prognostic marker and therapeutic target for HCC.

miR-142-5p suppresses proliferation and promotes apoptosis of human osteosarcoma cell line, HOS, by targeting PLA2G16 through the ERK1/2 signaling pathway

Previous studies have revealed that miR-142-5p serves a critical role in human cancer progression. However, the biological function of miR-142-5p in osteosarcoma (OS) development remains unclear. In the present study, the role of miR-142-5p in human OS HOS cells was determined, and the underlying mechanism involved was examined. Compared with the adjacent healthy tissues, the expression level of miR-142-5p was downregulated and the expression level of group XVI phospholipase A2 (PLA2G16) protein was upregulated in human OS tissues. The aforementioned results were also indicated in human OS HOS cells when compared with human fetal osteoblastic hFOB1.19 cells. Additionally, the results demonstrated that PLA2G16 was a direct target of miR-142-5p. miR-142-5p transfection upregulated the expression level of miR-142-5p and suppressed the expression level of PLA2G16 protein in HOS cells. MTT assays indicated a time-dependent decrease by miR-142-5p transfection in the proliferation of HOS cells. 5-bromo-2'-deoxyuridine incorporation assays confirmed that miR-142-5p transfection inhibited DNA synthesis in HOS cells. In addition, miR-142-5p transfection increased the Caspase-3 (CASP3) activity and apoptotic rate. Western blot analysis indicated that miR-142-5p transfection reduced BCL2, apoptosis regulator expression and upregulated the expression of CASP3 and BCL2 associated X, apoptosis regulator in HOS cells. Furthermore, miR-142-5p transfection decreased the expression levels of phosphorylated (p)-proto-oncogene, serine/threonine kinase, p-mitogen-activated protein kinase kinase, and p-extracellular signal-regulated kinase (ERK) 1/2 proteins in HOS cells. PLA2G16 overexpression restored the expression level of p-ERK 1/2 protein, which was reduced by miR-142-5p overexpression. MTT and CASP3 activity assays indicated that restoration of PLA2G16 reversed the tumour-suppressive role of miR-142-5p transfection in HOS cells. In conclusion, the results of the present study indicated that miR-142-5p suppressed proliferation and promoted apoptosis in human OS HOS cells by targeting PLA2G16 through ERK1/2 signaling pathway.

Dendritic cell factor 1 inhibits proliferation and migration and induces apoptosis of neuroblastoma cells by inhibiting the ERK signaling pathway

Neuroblastoma (NB) is the most common extracranial solid tumor that affects mainly children and has extremely high mortality and recurrence rates. A previous study revealed that dendritic cell factor 1 (DCF1), also called transmembrane protein 59, could activate apoptosis in glioma cells. In the present study, we applied immunofluorescence, western blot analysis, flow cytometry and cell tumorigenicity to investigate the DCF1 mechanisms involved in NB apoptosis. DCF1 was overexpressed in Neuro-2a and SK-N-SH cells through instantaneous transfection. The data revealed that overexpression of DCF1 could inhibit cell proliferation, migration, invasion and promote cell apoptosis in vitro, and suppress NB growth in vivo. The ERK1/2 signaling pathway, which promotes cell survival, was the target of DCF1 in neuroblastoma cells. All the results indicated that DCF1 could be a potential therapeutic target for the understanding and treatment of NB.

A Human Ribonuclease Variant and ERK-Pathway Inhibitors Exhibit Highly Synergistic Toxicity for Cancer Cells

Pancreatic-type ribonucleases (ptRNases) are prevalent secretory enzymes that catalyze the cleavage of RNA. Ribonuclease inhibitor (RI) is a cytosolic protein that has femtomolar affinity for ptRNases, affording protection from the toxic catalytic activity of ptRNases, which can invade human cells. A human ptRNase variant that is resistant to inhibition by RI is a cytotoxin that is undergoing a clinical trial as a cancer chemotherapeutic agent. We find that the ptRNase and protein kinases in the ERK pathway exhibit strongly synergistic toxicity toward lung cancer cells (including a KRAS^G12C variant) and melanoma cells (including BRAF^V600E variants). The synergism arises from inhibiting the phosphorylation of RI and thereby diminishing its affinity for the ptRNase. These findings link seemingly unrelated cellular processes, and suggest that the use of a kinase inhibitor to unleash a cytotoxic enzyme could lead to beneficial manifestations in the clinic.

KAP1 inhibits the Raf-MEK-ERK pathway to promote tumorigenesis in A549 lung cancer cells

Aberrant activation of the Raf-MEK-ERK pathway has frequently been associated with various cancers, especially lung cancer. However, the key regulators of this pathway are largely unknown. Using functional proteomics screening, we found that KAP1 interacts with c-Raf. Knocking out KAP1 decreased c-Raf phosphorylation at serine 259 and increased its phosphorylation at serine 338, which activated MEK and ERK. We detected higher KAP1 expression in lung cancer tissues than in normal peri-tumoral tissues. KAP1 knockdown arrested A549 lung cancer cells in the G0/G1 phase of the cell cycle and attenuated cell growth, metastasis, the epithelial-mesenchymal transition, angiogenesis, stemness, and colony formation. Furthermore, knocking out KAP1 remarkably increased the susceptibility of A549 cells to the anti-cancer drug 5-Fluorouracil, which correlated with increasing ERK phosphorylation. In vivo xenograft experiments suggested that KAP1 deficiency significantly decreases the tumorigenicity of A549 cells. Taken together, our findings indicate that KAP1 acts as a key module in the c-Raf-interactome complex and regulates lung cancer development through the Raf-MEK-ERK pathway. Therefore, KAP1 may represent a potential diagnosis biomarker and new treatment target for lung cancer.

ERK 1/2 Activation Mediates the Neuroprotective Effect of BpV(pic) in Focal Cerebral Ischemia-Reperfusion Injury

Bisperoxovanadium (pyridine-2-carboxyl) [bpV(pic)] is a commercially available PTEN inhibitor. Previous studies from us and others have shown that bpV(pic) confers neuroprotection in cerebral ischemia injury. We set up to determine whether ERK 1/2 activation plays a role in bpV(pic)-induced neuroprotective effect in cerebral ischemia injury. We found that the phosphorylation levels of Akt (p-AKT) and ERK1/2 (p-ERK 1/2) were down-regulated after cerebral ischemia–reperfusion injury. The injection of bpV(pic) after injury not only increased the level of p-AKT but also the level of p-ERK 1/2. While the inhibition of PTEN mediated the up-regulatation of p-AKT and p-ERK 1/2 by bpV(pic). Interestingly, the ERK 1/2 activation induced by bpV(pic) was also independent of the inhibition of PTEN. Our results indicate that bpV(pic) protects against OGD-induced neuronal death and promotes the functional recovery of stroke animals through PTEN inhibition and ERK 1/2 activation, respectively. This study suggests that the effect of bpV(pic) on ERK 1/2 signaling should be considered while using bpV(pic) as a PTEN inhibitor.

microRNA involvement in the onset and progression of Barrett's esophagus: a systematic review

Esophageal adenocarcinoma (EAC) is a highly aggressive malignancy that develops from Barrett's esophagus (BE), an intestinal metaplasia of the distal esophagus. microRNAs (miRNAs), short non-coding regulatory RNAs, are frequently dysregulated in BE and are thought to play key roles in the onset of BE and its progression to EAC. miRNAs thus have potential diagnostic and prognostic value and are increasingly being used as cancer biomarkers. This review summarizes the current literature related to miRNAs that are dysregulated in BE within the context of Hedgehog, Notch, MAPK, NF kappa-B, Wnt and epithelial-mesenchymal transition (EMT) signaling which are thought to drive BE onset and progression. This comprehensive analysis of miRNAs and their associated signaling in the regulation of BE provides an overview of vital discoveries in this field and highlights gaps in our understanding of BE pathophysiology that warrant further investigation.

Perspective on the dynamics of cancer

BACKGROUND

The genetic diversity of cancer and the dynamic interactions between heterogeneous tumor cells, the stroma and immune cells present daunting challenges to the development of effective cancer therapies. Although cancer biology is more understood than ever, this has not translated into therapies that overcome drug resistance, cancer recurrence and metastasis. The future development of effective therapies will require more understanding of the dynamics of homeostatic dysregulation that drives cancer growth and progression.

RESULTS

Cancer dynamics are explored using a model involving genes mediating the regulatory interactions between the signaling and metabolic pathways. The exploration is informed by a proposed genetic dysregulation measure of cellular processes. The analysis of the interaction dynamics between cancer cells, cancer associated fibroblasts, and tumor associate macrophages suggests that the mutual dependence of these cells promotes cancer growth and proliferation. In particular, MTOR and AMPK are hypothesized to be concurrently activated in cancer cells by amino acids recycled from the stroma. This leads to a proliferative growth supported by an upregulated glycolysis and a tricarboxylic acid cycle driven by glutamine sourced from the stroma. In other words, while genetic aberrations ignite carcinogenesis and lead to the dysregulation of key cellular processes, it is postulated that the dysregulation of metabolism locks cancer cells in a state of mutual dependence with the tumor microenvironment and deepens the tumor's inflammation and immunosuppressive state which perpetuates as a result the growth and proliferation dynamics of cancer.

CONCLUSIONS

Cancer therapies should aim for a progressive disruption of the dynamics of interactions between cancer cells and the tumor microenvironment by targeting metabolic dysregulation and inflammation to partially restore tissue homeostasis and turn on the immune cancer kill switch. One potentially effective cancer therapeutic strategy is to induce the reduction of lactate and steer the tumor microenvironment to a state of reduced inflammation so as to enable an effective intervention of the immune system. The translation of this therapeutic approach into treatment regimens would however require more understanding of the adaptive complexity of cancer resulting from the interactions of cancer cells with the tumor microenvironment and the immune system.