Amplified Ras-MAPK signal states correlate with accelerated EGFR internalization, cytostasis and delayed HER2 tumor onset in Fer-deficient model systems

The emerging role of deubiquitylating enzyme USP21 as a potential therapeutic target in cancer

Although certain members of the Ubiquitin-specific peptidases (USPs) have been recognized as promising therapeutic targets for various diseases, research progress regarding USP21 has been relatively sluggish in its early stages. USP21 is a crucial member of the USPs subfamily, involved in diverse cellular processes such as apoptosis, DNA repair, and signal transduction. Research findings from the past decade demonstrate that USP21 mediates the deubiquitination of multiple well-known target proteins associated with critical cellular processes relevant to both disease and homeostasis, particularly in various cancers.This reviewcomprehensively summarizes the structure and biological functions of USP21 with an emphasis on its role in tumorigenesis, and elucidates the advances on the discovery of tens of small-molecule inhibitors targeting USP21, which suggests that targeting USP21 may represent a potential strategy for cancer therapy.

Lactate dehydrogenase A is implicated in the pathogenesis of B-cell lymphoma through regulation of the FER signaling pathway

Lactate dehydrogenase A (LDHA) is highly expressed in various tumors. However, the role of LDHA in the pathogenesis of B-cell lymphoma remains unclear. Analysis of data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases revealed an elevated LDHA expression in diffuse large B-cell lymphoma (DLBC) tissues compared with normal tissues. Similarly, our results demonstrated a significant increase in LDHA expression in tumor tissues from the patients with B-cell lymphoma compared with those with lymphadenitis. To further elucidate potential roles of LDHA in B-cell lymphoma pathogenesis, we silenced LDHA in the Raji cells (a B-cell lymphoma cell line) using shRNA techniques. Silencing LDHA led to reduced mitochondrial membrane integrity, adenosine triphosphate (ATP) production, glycolytic activity, cell viability and invasion. Notably, LDHA knockdown substantially suppressed in vivo growth of Raji cells and extended survival in mice bearing lymphoma (Raji cells). Moreover, proteomic analysis identified feline sarcoma-related protein (FER) as a differential protein positively associated with LDHA expression. Treatment with E260, a FER inhibitor, significantly reduced the metabolism, proliferation and invasion of Raji cells. In summary, our findings highlight that LDHA plays multiple roles in B-cell lymphoma pathogenesis via FER pathways, establishing LDHA/FER may as a potential therapeutic target.

Extracellular Signal-Regulated Kinases: One Pathway, Multiple Fates

This comprehensive review delves into the multifaceted aspects of ERK signaling and the intricate mechanisms underlying distinct cellular fates. ERK1 and ERK2 (ERK) govern proliferation, transformation, epithelial-mesenchymal transition, differentiation, senescence, or cell death, contingent upon activation strength, duration, and context. The biochemical mechanisms underlying these outcomes are inadequately understood, shaped by signaling feedback and the spatial localization of ERK activation. Generally, ERK activation aligns with the Goldilocks principle in cell fate determination. Inadequate or excessive ERK activity hinders cell proliferation, while balanced activation promotes both cell proliferation and survival. Unraveling the intricacies of how the degree of ERK activation dictates cell fate requires deciphering mechanisms encompassing protein stability, transcription factors downstream of ERK, and the chromatin landscape.

Fer-mediated activation of the Ras-MAPK signaling pathway drives the proliferation, migration, and invasion of endometrial carcinoma cells

BACKGROUND

The role of Feline sarcoma-related protein (Fer) in various cancers has been extensively studied, but its specific involvement and underlying mechanisms in the progression of endometrial carcinoma (EC) are yet to be fully understood.

METHODS

The expression levels of Fer were assessed in EC tissues and cell lines using real-time quantitative PCR and western blot analysis. CCK-8 assay, Edu staining, transwell assays, and flow cytometry, were conducted to evaluate the impact of Fer on EC cells. Furthermore, a mice xenograft model and immunohistochemistry (IHC) staining were utilized for in vivo analysis. The levels of Ras, pMek1/2, and pErk1/2 were determined by western blot assay. Ras-MAPK signaling pathway inhibitor was utilized to study the regulatory role of Fer on EC cells.

RESULTS

Our findings revealed that Fer exhibited upregulation in both EC tissues and cell lines, concomitant with the activation of the Ras-MAPK signaling pathway. Silencing of Fer resulted in the suppression of cell proliferation, migration, invasion, and Ras-MAPK signaling pathway, while promoted hypoxia-induced apoptosis in RL95-2 and KLE cells. Fer overexpression stimulated cell proliferation, migration, invasion, and Ras-MAPK signaling pathway in Ishikawa and AN3-CA cells, which were reversed after treatment with either Ras or MAPK inhibitor. Moreover, silencing of Fer suppressed tumor growth and downregulated the expression of Ki-67, Ras, pMek1/2, and pErk1/2, but had no significant effect on Mek1/2 and Erk1/2, while upregulated caspase-3 expression in vivo.

CONCLUSION

In summary, the upregulation of Fer in EC cells resulted in the enhancement of cell proliferation, migration, and invasion through the activation of the Ras-MAPK signaling pathway.

High-resolution structural analysis shows how different crystallographic environments can induce alternative modes of binding of a phosphotyrosine peptide to the SH2 domain of Fer tyrosine kinase

Fes and Fes-related (Fer) protein tyrosine kinases (PTKs) comprise a subfamily of nonreceptor tyrosine kinases characterized by a unique multidomain structure composed of an N-terminal Fer/CIP4 homology-Bin/Amphiphysin/Rvs (F-BAR) domain, a central Src homology 2 (SH2) domain, and a C-terminal PTK domain. Fer is ubiquitously expressed, and upregulation of Fer has been implicated in various human cancers. The PTK activity of Fes has been shown to be positively regulated by the binding of phosphotyrosine-containing ligands to the SH2 domain. Here, the X-ray crystal structure of human Fer SH2 domain bound to a phosphopeptide that has D-E-pY-E-N-V-D sequence is reported at 1.37 å resolution. The asymmetric unit (ASU) contains six Fer-phosphopeptide complexes, and the structure reveals three distinct binding modes for the same phosphopeptide. At four out of the six binding sites in the ASU, the phosphopeptide binds to Fer SH2 domain in a type I β-turn conformation, and this could be the optimal binding mode of this phosphopeptide. At the other two binding sites in the ASU, it appears that spatial proximity of neighboring SH2 domains in the crystal induces alternative modes of binding of this phosphopeptide.

YY1 inhibits the migration and invasion of pancreatic ductal adenocarcinoma by downregulating the FER/STAT3/MMP2 signaling pathway

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis and a high mortality rate. The transcription factor YY1 acts as an inhibitor of many types of tumors. We found that YY1 knockdown promoted the invasion and migration of PANC-1 and BxPC-3 cells; FER knockdown partially restored the promotion of pancreatic cancer caused by YY1 knockdown. In vivo experiments yielded the same results. According to luciferase reporter gene, electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays, YY1 directly binds to the FER promoter region. Moreover, higher level FER expression results in a worse TNM stage and prognosis for patients with PDAC. Furthermore, by downregulating FER, YY1 inhibits the formation of the STAT3-MMP2 complex, thereby suppressing expression of MMP2 and ultimately inhibiting the migration and invasion of pancreatic cancer. Our study demonstrates that the YY1/FER/STAT3/MMP2 axis is associated with the progression of pancreatic cancer and may provide a new therapeutic target for the treatment of pancreatic cancer.

Genetic disruption of calpain-1 and calpain-2 attenuates tumorigenesis in mouse models of HER2+ breast cancer and sensitizes cancer cells to doxorubicin and lapatinib

Calpains are a family of calcium activated cysteine proteases which participate in a wide range of cellular functions including migration, invasion, autophagy, programmed cell death, and gene expression. Calpain-1 and calpain-2 isoforms are ubiquitously expressed heterodimers composed of isoform specific catalytic subunits coupled with an obligate common regulatory subunit encoded by capns1. Here, we report that conditional deletion of capns1 disrupted calpain-1 and calpain-2 expression and activity, and this was associated with delayed tumorigenesis and altered signaling in a transgenic mouse model of spontaneous HER2⁺ breast cancer and effectively blocked tumorigenesis in an orthotopic engraftment model. Furthermore, capns1 knockout in a tumor derived cell line correlated with enhanced sensitivity to the chemotherapeutic doxorubicin and the HER2/EGFR tyrosine kinase inhibitor lapatinib. Collectively, these results indicate pro-tumorigenic roles for calpains-1/2 in HER2⁺ breast cancer and provide evidence that calpain-1/2 inhibitors could have anti-tumor effects if used either alone or in combination with chemotherapeutics and targeted agents.

MAPK/AP-1 pathway regulates benzidine-induced cell proliferation through the control of cell cycle in human normal bladder epithelial cells

Bladder cancer is the most common malignancy of the urinary tract. Long-term exposure to benzidine is one of the major causes of bladder cancer. However, the mechanism of benzidine-induced bladder cancer is not yet sufficiently characterized. Dysregulated cell proliferation serves a critical role in cancer initiation and development; whether benzidine promotes cell proliferation, and the role of MAPKs in this process, have not previously been investigated. The present study aimed to investigate the benzidine-induced modulation of intracellular mitogen-activated protein kinases (MAPKs) and activator protein-1 (AP-1) signaling cascades on cell proliferation in SV-40 immortalized human uroepithelial cells (SV-HUC-1). It was identified that benzidine exposure enhanced the proliferation of SV-HUC-1 cells, promoted the transition of cells from G1 to S phase and altered the expression level of cell cycle-associated genes at the mRNA and protein levels. Furthermore, exposure of the SV-HUC-1 cells to benzidine was associated with the activation of MAPKs, including extracellular regulated protein kinases 1 and 2, p38 and Jun N-terminal kinase. The downstream target of MAPKs, AP-1 monomers, was also activated. Benzidine-induced proliferation was reversed by MAPK-specific inhibitors. Thus, the present study demonstrated that benzidine enhances the proliferation of bladder cells via activating the MAPK/AP-1 pathway, which may provide novel insights into the molecular mechanisms of benzidine-initiated bladder tumorigenesis, as well as cancer prevention.

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

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

Injection of nanoparticles containing the anticancer drug gefitinib and the immunosuppressant cyclosporin A reverses drug-resistant cancer growth in mice. The development of multidrug resistance is the main reason why many forms of chemotherapy fail. Cyclosporin A, a drug used to prevent immune rejection after organ transplantation, has previously been shown to enhance the potency of gefitinib. Hangxiang Wang and colleagues at Zhejiang University, Hangzhou, China, have successfully combined cyclosporin A and gefitinib, two poorly water-soluble and slowly absorbed drugs, into stable injectable nanoparticles that delay the growth of gefitinib resistant human lung cancer cells as well as the growth of drug resistant tumors in mice. Importantly, this novel co-formulation was more effective than oral co-administration of the two drugs. Further investigation into this drug delivery route could yield much needed alternative treatments for patients with multidrug-resistant cancers.

Spatial regulation of signaling by the coordinated action of the protein tyrosine kinases MET and FER

A critical aspect of understanding the regulation of signal transduction is not only to identify the protein-protein interactions that govern assembly of signaling pathways, but also to understand how those pathways are regulated in time and space. In this report, we have applied both gain-of-function and loss-of-function analyses to assess the role of the non-receptor protein tyrosine kinase FER in activation of the HGF Receptor protein tyrosine kinase MET. Overexpression of FER led to direct phosphorylation of several signaling sites in MET, including Tyr1349, but not the activation loop residues Tyr1234/5; in contrast, suppression of FER by RNAi revealed that phosphorylation of both a C-terminal signaling site (Tyr1349) and the activation loop (Tyr1234/5) were influenced by the function of this kinase. Adaptin β, a component of the adaptor protein complex 2 (AP-2) that links clathrin to receptors in coated vesicles, was recruited to MET following FER-mediated phosphorylation. Furthermore, we provide evidence to support a role of FER in maintaining plasma membrane distribution of MET and thereby delaying protein-tyrosine phosphatase PTP1B-mediated inactivation of the receptor. Simultaneous up-regulation of FER and down-regulation of PTP1B observed in ovarian carcinoma-derived cell lines would be expected to contribute to persistent activation of HGF-MET signaling, suggesting that targeting of both FER and MET may be an effective strategy for therapeutic intervention in ovarian cancer.

Electroporation-mediated delivery of FER gene enhances innate immune response and improves survival in a murine model of pneumonia

Previously, we reported that electroporation-mediated (EP) delivery of the FER gene improved survival in a combined trauma-pneumonia model. The mechanism of this protective effect is unknown. In this paper, we performed a pneumonia model in C57/BL6 mice with 500 CFU of Klebsiella pneumoniae. After inoculation, a plasmid encoding human FER was delivered by EP into the lung (PNA/pFER-EP). Survival of FER-treated vs. controls (PNA; PNA/EP-pcDNA) was recorded. In parallel cohorts, bronchial alveolar lavage (BAL) and lung were harvested at 24 and 72 h with markers of infection measured. FER-EP-treated animals reduced bacterial counts and had better 5-day survival compared to controls (80 vs. 20 vs. 25%; p < 0.05). Pre-treatment resulted in 100% survival. With FER, inflammatory monocytes were quickly recruited into BAL. These cells had increased surface expression for Toll-receptor 2 and 4, and increased phagocytic and myeloperoxidase activity at 24 h. Samples from FER electroporated animals had increased phosphorylation of STAT transcription factors, varied gene expression of IL1β, TNFα, Nrf2, Nlrp3, Cxcl2, HSP90 and increased cytokine production of TNF-α, CCL-2, KC, IFN-γ, and IL-1RA. In a follow-up experiment, using Methicillin-resistant Staphylococcus aureus (MRSA) similar bacterial reduction effects were obtained with FER gene delivery. We conclude that FER overexpression improves survival through STAT activation enhancing innate immunity and accelerating bacterial clearance in the lung. This constitutes a novel mechanism of inflammatory regulation with therapeutic potential in the setting of hospital-acquired pneumonia.

MicroRNA181c inhibits prostate cancer cell growth and invasion by targeting multiple ERK signaling pathway components

BACKGROUND

The ERK signaling pathway is frequently deregulated in tumorigenesis, mostly by classical mechanisms such as gene mutation of its components (eg, RAS and RAF). However, whether and how multiple key components of ERK pathway are regulated by microRNAs are not clear.

METHODS

We firstly predicted post-transcriptional regulation of multiple key components of the ERK signaling pathway by miR181c through bioinformatics analysis, and then confirmed the post-transcriptional regulation by dual luciferase reporter gene assays and Western blot analysis. The biological effects of miR181c on prostate cancer cell proliferation, apoptosis, migration, and invasion were measured by CCK-8 assay, flow cytometry, wound scratch assay, transwell cell migration, and invasion assays.

RESULTS

miR181c post-transcriptionally regulated multiple key members of the ERK signaling pathway, including extracellular signal-regulated kinase 2 (ERK2), ribosomal S6 kinase 2 (RSK2), serum response factor (SRF), and FBJ murine osteosarcoma viral oncogene homolog (c-Fos). Ectopic expression of miR181c mimics effectively suppressed prostate cancer cell proliferation, migration, and invasion, but promoted cell apoptosis. Furthermore, miR181c treatment combined with the multi-kinase inhibitor sorafenib significantly enhanced these anti-tumor effects.

CONCLUSIONS

Downregulation of miR181c results in deregulated ERK signaling and promotes prostate cancer cell growth and metastasis.

Cigarette smoke induced urocystic epithelial mesenchymal transition via MAPK pathways

Cigarette smoke has been shown to be a major risk factor for bladder cancer. Epithelial-mesenchymal transition (EMT) is a crucial process in cancer development. The role of MAPK pathways in regulating cigarette smoke-triggered urocystic EMT remains to be elucidated. Human normal urothelial cells and BALB/c mice were used as in vitro and in vivo cigarette smoke exposure models. Exposure of human normal urothelial cells to cigarette smoke induced morphological change, enhanced migratory and invasive capacities, reduced epithelial marker expression and increased mesenchymal marker expression, along with the activation of MAPK pathways. Moreover, we revealed that ERK1/2 and p38 inhibitors, but rather JNK inhibitor, effectively attenuated cigarette smoke-induced urocystic EMT. Importantly, the regulatory function of ERK1/2 and p38 pathways in cigarette smoke-triggered urocystic EMT was further confirmed in mice exposed to CS for 12 weeks. These findings could provide new insight into the molecular mechanisms of cigarette smoke-associated bladder cancer development as well as its potential intervention.

Potential Anticancer Mechanisms of a Novel EGFR/DNA-Targeting Combi-Molecule (JDF12) against DU145 Prostate Cancer Cells: An iTRAQ-Based Proteomic Analysis

The development of multitargeting drugs is an emerging trend in cancer research. To promote further development and clinical application of multitargeting drugs, this research was performed. MTT assay and flow cytometry of Annexin V/propidium iodide staining were used to confirm the proapoptotic efficacy of a novel combi-targeting molecule, JDF12, against DU145 prostate cancer (PCa) cells. Differentially expressed proteins between control and JDF12-treated cultures were revealed by isobaric tags for relative and absolute quantitation (iTRAQ), and part of them was confirmed by quantitative PCR. Differentially expressed proteins were further analyzed for function, pathway association, and protein−protein interactions using GO, KEGG, and STRING databases. A total of 119 differentially expressed proteins, 70 upregulated and 49 downregulated, were implicated in the anticancer effects of JDF12. Many of these proteins are involved in biosynthesis, response to stress, energy metabolism, and signal transduction. This study provides important information for understanding the anti-PCa mechanisms of JDF12, and well-designed combi-targeting drugs may possess stronger anticancer efficacy than single-targeting drugs and are thus promising candidates for clinical application.

A novel Fer/FerT targeting compound selectively evokes metabolic stress and necrotic death in malignant cells

Disruption of the reprogrammed energy management system of malignant cells is a prioritized goal of targeted cancer therapy. Two regulators of this system are the Fer kinase, and its cancer cell specific variant, FerT, both residing in subcellular compartments including the mitochondrial electron transport chain. Here, we show that a newly developed inhibitor of Fer and FerT, E260, selectively evokes metabolic stress in cancer cells by imposing mitochondrial dysfunction and deformation, and onset of energy-consuming autophagy which decreases the cellular ATP level. Notably, Fer was also found to associate with PARP-1 and E260 disrupted this association thereby leading to PARP-1 activation. The cooperative intervention with these metabolic pathways leads to energy crisis and necrotic death in malignant, but not in normal human cells, and to the suppression of tumors growth in vivo. Thus, E260 is a new anti-cancer agent which imposes metabolic stress and cellular death in cancer cells.

The tyrosine-kinases Fer/FerT associate with the mitochondrial electron transport chain in cancer cells supporting their metabolic reprogramming. Here the authors discover a compound that disrupts Fer /FerT activity and selectively induces cell death of cancer cell lines displaying anti-tumor activity in vivo.

HGF-independent regulation of MET and GAB1 by nonreceptor tyrosine kinase FER potentiates metastasis in ovarian cancer

In this study, Fan et al. report a novel ligand- and autophosphorylation-independent activation of MET through the nonreceptor tyrosine kinase FER. The findings show that levels of FER were elevated in ovarian cancer cell lines and that loss of FER impaired the metastasis of ovarian cancer cells in vivo, providing new insights into signaling events that underlie metastasis in ovarian cancer cells.

Ovarian cancer cells disseminate readily within the peritoneal cavity, which promotes metastasis, and are often resistant to chemotherapy. Ovarian cancer patients tend to present with advanced disease, which also limits treatment options; consequently, new therapies are required. The oncoprotein tyrosine kinase MET, which is the receptor for hepatocyte growth factor (HGF), has been implicated in ovarian tumorigenesis and has been the subject of extensive drug development efforts. Here, we report a novel ligand- and autophosphorylation-independent activation of MET through the nonreceptor tyrosine kinase feline sarcoma-related (FER). We demonstrated that the levels of FER were elevated in ovarian cancer cell lines relative to those in immortalized normal surface epithelial cells and that suppression of FER attenuated the motility and invasive properties of these cancer cells. Furthermore, loss of FER impaired the metastasis of ovarian cancer cells in vivo. Mechanistically, we demonstrated that FER phosphorylated a signaling site in MET: Tyr1349. This enhanced activation of RAC1/PAK1 and promoted a kinase-independent scaffolding function that led to recruitment and phosphorylation of GAB1 and the specific activation of the SHP2–ERK signaling pathway. Overall, this analysis provides new insights into signaling events that underlie metastasis in ovarian cancer cells, consistent with a prometastatic role of FER and highlighting its potential as a novel therapeutic target for metastatic ovarian cancer.

Epidermal growth factor receptor (EGFR)-MAPK-nuclear factor(NF)-κB-IL8: A possible mechanism of particulate matter(PM) 2.5-induced lung toxicity

Airway inflammation plays a central role in the pathophysiology of diverse pulmonary diseases. In this study, we investigated whether exposure to particulate matter (PM) 2.5, a PM with an aerodynamic diameter of less than 2.5 µm, enhances inflammation-related toxicity in the human respiratory system through activation of the epidermal growth factor receptor (EGFR) signaling pathway. Through cytokine antibody array analysis of two extracts of PM_2.5 [water (W-PM_2.5 ) and organic (O-PM_2.5 ) soluble extracts] exposed to A549 (human alveolar epithelial cell), we identified eight cytokines changed their expression with W-PM_2.5 and three cytokines with O-PM_2.5 . Among them, epidermal growth factor (EGF) was commonly up-regulated by W-PM_2.5 and O-PM_2.5 . Then, in both groups, we can identify the increase in EGF receptor protein levels. Likewise, increases in the phosphorylation of ERK1/2 MAP kinase and acetylation of nuclear factor(NF)-κB were detected. We also detected an increase in IL-8 that was related to inflammatory response. And using the erlotinib as an inhibitor of EGFR, we identified the erlotinib impaired the phosphorylation of EGFR, ERK1/2, acetylation of NF-κB proteins and decreased IL-8. Furthermore, at in vivo model, we were able to identify similar patterns. These results suggest that PM_2.5 may contribute to an abnormality in the human respiratory system through EGFR, MAP kinase, NF-κB, and IL-8 induced toxicity signaling. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1628-1636, 2017.

Stromal expression of Fer suppresses tumor progression in renal cell carcinoma and is a predictor of survival

Fps/Fes related (Fer) is a non-receptor tyrosine kinase that is expressed in fibroblasts, immune cells and endothelial cells. Fer serves an important pathological role in cell survival, angiogenesis and the immune system. However, the pathological role of Fer expression in the stromal cells surrounding renal cell carcinoma (RCC) has not been previously investigated. In the present study, immunohistochemical analysis of Fer was performed using the formalin-fixed tissue samples of 152 patients with RCC. The proliferative and apoptotic indices were used to represent the percentage of proliferation marker protein Ki-67- and cleaved caspase-3-positive cells, respectively. The microvessel density was defined as the number of cluster of differentiation (CD) 31-positively stained vessels/mm². In addition, CD57⁺ and CD68⁺ cells were counted using semi-quantification of natural killer (NK) cells and macrophages. Fer expression in stromal cells was negatively associated with Fuhrman grade, pathological tumor stage and metastasis (P<0.001). Fer expression in stromal cells was negatively associated with CD68⁺ macrophage density, whereas it was positively associated with CD57⁺ NK cell density. Kaplan-Meier estimators indicated that decreased stromal Fer expression was a predictive marker of decreased cause-specific survival rate (P<0.001). Furthermore, low expression of Fer was identified as being an independent marker of decreased cause-specific survival using multivariate analysis (hazard ratio, 7.4; 95% confidence interval, 1.7-33.0; P<0.001). The results of the present study suggested that low Fer expression in stromal cells is associated with increased malignant aggressiveness and decreased survival in patients with RCC. CD57⁺ NK cell and CD68⁺ macrophage regulation in cancer-stromal tissue is considered to affect RCC pathology.

Electroporation-mediated delivery of the FER gene in the resolution of trauma-related fatal pneumonia

Injured patients with lung contusion (LC) are at risk of developing bacterial pneumonia (PNA) followed by sepsis and death. A recent genome-wide association study (GWAS) showed FER gene expression positively correlating with survival rates among individuals with above conditions. We sought to determine whether electroporation (EP)-mediated delivery of FER gene could indeed improve survival, in a lethal model of combined LC and PNA. C57BL/6 mice sustained unilateral LC, which preceded a 500 Klebsiella colony forming unit (CFU) inoculation by 6 h. In-between these insults, human FER plasmid (pFER) was introduced into the lungs followed by eight EP pulses applied externally (10 ms at 200 V cm^-1). Control groups included EP of empty vector (pcDNA3) or Na⁺/K⁺-ATPase genes (pPump) and no treatment (LC+PNA). We recorded survival, histology, lung mechanics, bronchial alveolar lavage (BAL) fluid, FER and inflammatory gene expression and bacteriology. The data show that 7-day survival was significantly improved by pFER compared with control groups. pFER increased BAL monocytes and activated antibacterial response genes (nitric oxide synthase (NOS), Fizz). pFER treatment showed decreased lung and blood Klebsiella counts reaching, in some cases, complete sterilization. In conclusion, FER gene delivery promoted survival in LC+PNA mice via recruitment of activated immune cells, improving efficiency of bacterial clearance within contused lung.

The tyrosine kinase FER is responsible for the capacitation-associated increase in tyrosine phosphorylation in murine sperm

Sperm capacitation is required for fertilization. At the molecular level, this process is associated with fast activation of protein kinase A. Downstream of this event, capacitating conditions lead to an increase in tyrosine phosphorylation. The identity of the tyrosine kinase(s) mediating this process has not been conclusively demonstrated. Recent experiments using stallion and human sperm have suggested a role for PYK2 based on the use of small molecule inhibitors directed against this kinase. However, crucially, loss-of-function experiments have not been reported. Here, we used both pharmacological inhibitors and genetically modified mice models to investigate the identity of the tyrosine kinase(s) mediating the increase in tyrosine phosphorylation in mouse sperm. Similar to stallion and human, PF431396 blocks the capacitation-associated increase in tyrosine phosphorylation. Yet, sperm from Pyk2(-/-) mice displayed a normal increase in tyrosine phosphorylation, implying that PYK2 is not responsible for this phosphorylation process. Here, we show that PF431396 can also inhibit FER, a tyrosine kinase known to be present in sperm. Sperm from mice targeted with a kinase-inactivating mutation in Fer failed to undergo capacitation-associated increases in tyrosine phosphorylation. Although these mice are fertile, their sperm displayed a reduced ability to fertilize metaphase II-arrested eggs in vitro.

Context-specific flow through the MEK/ERK module produces cell- and ligand-specific patterns of ERK single and double phosphorylation

The same pathway, such as the mitogen-activated protein kinase (MAPK) pathway, can produce different cellular responses, depending on stimulus or cell type. We examined the phosphorylation dynamics of the MAPK kinase MEK and its targets extracellular signal-regulated kinase 1 and 2 (ERK1/2) in primary hepatocytes and the transformed keratinocyte cell line HaCaT A5 exposed to either hepatocyte growth factor or interleukin-6. By combining quantitative mass spectrometry with dynamic modeling, we elucidated network structures for the reversible threonine and tyrosine phosphorylation of ERK in both cell types. In addition to differences in the phosphorylation and dephosphorylation reactions, the HaCaT network model required two feedback mechanisms, which, as the experimental data suggested, involved the induction of the dual-specificity phosphatase DUSP6 and the scaffold paxillin. We assayed and modeled the accumulation of the double-phosphorylated and active form of ERK1/2, as well as the dynamics of the changes in the monophosphorylated forms of ERK1/2. Modeling the differences in the dynamics of the changes in the distributions of the phosphorylated forms of ERK1/2 suggested that different amounts of MEK activity triggered context-specific responses, with primary hepatocytes favoring the formation of double-phosphorylated ERK1/2 and HaCaT A5 cells that produce both the threonine-phosphorylated and the double-phosphorylated form. These differences in phosphorylation distributions explained the threshold, sensitivity, and saturation of the ERK response. We extended the findings of differential ERK phosphorylation profiles to five additional cultured cell systems and matched liver tumor and normal tissue, which revealed context-specific patterns of the various forms of phosphorylated ERK.

ERK5 negatively regulates tobacco smoke-induced pulmonary epithelial-mesenchymal transition

As the primary cause of lung cancer, tobacco smoke (TS) promotes the initiation and progression of lung tumorigenesis. Epithelial-mesenchymal transition (EMT) is a crucial process involved in cell malignant transformation. The role of ERK5, the lesser studied member of MAPKs family, in regulating TS-triggered pulmonary EMT has not been investigated. Normal human bronchial epithelial cells and BALB/c mice were used as in vitro and in vivo TS exposure models. Exposure of normal human bronchial epithelial cells to TS for 7 days induced morphological change, enhanced migratory and invasive capacities, reduced epithelial marker expression and increased mesenchymal marker expression. Importantly, we demonstrated for the first time that ERK5 negatively regulated TS-mediated lung epithelial EMT, as evidenced by the findings that TS suppressed ERK5 activation, and that TS-triggered EMT was mimicked with ERK5 inhibition and reversed by ERK5 overexpression. The negative regulation of ERK5 on pulmonary EMT was further confirmed in mice exposed to TS for 12 weeks. Taken together, our data suggest that ERK5 negatively regulates TS-mediated pulmonary EMT. These findings provide new insight into the molecular mechanisms of TS-associated lung tumorigenesis and may open up new avenues in the search for potential target of lung cancer intervention.