MEK5/ERK5 activation regulates colon cancer stem-like cell properties

An ERK5-PFKFB3 axis regulates glycolysis and represents a therapeutic vulnerability in pediatric diffuse midline glioma

Metabolic reprogramming in pediatric diffuse midline glioma is driven by gene expression changes induced by the hallmark histone mutation H3K27M, which results in aberrantly permissive activation of oncogenic signaling pathways. Previous studies of diffuse midline glioma with altered H3K27 (DMG-H3K27a) have shown that the RAS pathway, specifically through its downstream kinase, extracellular-signal-related kinase 5 (ERK5), is critical for tumor growth. Further downstream effectors of ERK5 and their role in DMG-H3K27a metabolic reprogramming have not been explored. We establish that ERK5 is a critical regulator of cell proliferation and glycolysis in DMG-H3K27a. We demonstrate that ERK5 mediates glycolysis through activation of transcription factor MEF2A, which subsequently modulates expression of glycolytic enzyme PFKFB3. We show that in vitro and mouse models of DMG-H3K27a are sensitive to the loss of PFKFB3. Multi-targeted drug therapy against the ERK5-PFKFB3 axis, such as with small-molecule inhibitors, may represent a promising therapeutic approach in patients with pediatric diffuse midline glioma.

ERK2 Is a Promoter of Cancer Cell Growth and Migration in Colon Adenocarcinoma

ERK1/2 phosphorylation is frequently downregulated in the early phase of colon tumorigenesis with subsequent activation of ERK5. In the current work, we studied the advantages of ERK1/2 downregulation for tumor growth by dissecting the individual functions of ERK1 and ERK2. The patient sample data demonstrated decreased ERK1/2 phosphorylation in the early phase of tumorigenesis followed by increased phosphorylation in late-stage colon adenocarcinomas with intratumoral invasion or metastasis. In vitro results indicated that SOD3-mediated coordination of small GTPase RAS regulatory genes inhibited RAS-ERK1/2 signaling. In vitro and in vivo studies suggested that ERK2 has a more prominent role in chemotactic invasion, collective migration, and cell proliferation than ERK1. Of note, simultaneous ERK1 and ERK2 expression inhibited collective cell migration and proliferation but tended to promote invasion, suggesting that ERK1 controls ERK2 function. According to the present data, phosphorylated ERK1/2 at the early phase of colon adenocarcinoma limits tumor mass expansion, whereas reactivation of the kinases at the later phase of colon carcinogenesis is associated with the initiation of metastasis. Additionally, our results suggest that ERK1 is a regulatory kinase that coordinates ERK2-promoted chemotactic invasion, collective migration, and cell proliferation. Our findings indicate that ROS, especially H2O2, are associated with the regulation of ERK1/2 phosphorylation in colon cancer by either increasing or decreasing kinase activity. These data suggest that ERK2 has a growth-promoting role and ERK1 has a regulatory role in colon tumorigenesis, which could lead to new avenues in the development of cancer therapy.

In vitro siRNA-mediated GPX4 and AKT1 silencing in oxaliplatin resistance cancer cells induces ferroptosis and apoptosis

Oxaliplatin is a member of platinum-based chemotherapy drugs frequently used in colorectal cancer (CRC). However, resistance to oxaliplatin causes tumor progression and metastasis. Akt1 and Gpx4 are essential regulator genes of apoptosis and ferroptosis pathways. Inhibition of these genes might eradicate oxaliplatin resistance in resistant CRC cells. We compared two cell death strategies to reverse drug resistance in Caco-2 and HT-29 oxaliplatin-resistant cell lines. We used the AKT1-specific siRNA to induce apoptosis. Also, GPX4-specific siRNA and FIN56 were utilized to generate ferroptosis. The effect of these treatments was assessed by reactive oxygen species (ROS) formation, cell viability, and protein expression level assays. Besides, the expression of GPX4, CoQ10, and NRF2 was assessed in both cell lines after treatments. Correctly measuring the expression of these responsible genes and proteins confirms the occurrence of different types of cell death. In addition, the ability of Akt1/ GPX4 siRNA in resensitizing HT-29 and Caco-2 oxaliplatin resistance cells was evaluated. Our finding showed that the upregulation of GPX4/siRNA caused a reduction in GPX4 and CoQ10 expressions in both cell lines. However, the expression level of NRF2 showed the same level in our cell lines, so we observed a downregulation of NRF2 in resistant CRC cell lines. Cell viability assay indicated that induction of ferroptosis by GPX4/siRNA or FIN56 and apoptosis by Akt1/siRNA in resistant cell lines could reverse the oxaliplatin resistance. We concluded that downregulation of Akt1 or Gpx4 could increase the efficacy of oxaliplatin to overcome the resistance compared to FIN56.

The significance of ERK5 catalytic-independent functions in disease pathways

Extracellular signal-regulated kinase 5 (ERK5), also known as BMK1 or MAPK7, represents a recent addition to the classical mitogen-activated protein kinase (MAPK) family. This family includes well-known members such as ERK1/2, c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK), as well as atypical MAPKs such as ERK3, ERK4, ERK7 (ERK8), and Nemo-like kinase (NLK). Comprehensive reviews available elsewhere provide detailed insights into ERK5, which interested readers can refer to for in-depth knowledge (Nithianandarajah-Jones et al., 2012; Monti et al., Cancers (Basel), 2022, 14). The primary aim of this review is to emphasize the essential characteristics of ERK5 and shed light on the intricate nature of its activation, with particular attention to the catalytic-independent functions in disease pathways.

Aberrant expression of WNK lysine deficient protein kinase 1 is associated with poor prognosis of colon adenocarcinoma

BACKGROUNDS

WNK1 (WNK lysine deficient protein kinase 1) is a kind of protein kinase and participates in angiogenesis, having a potent tumor promoting role. WNK1 is ubiquitously expressed, and its upregulated expression has been reported in several tumor types.

AIMS

Here, we aimed to investigate the correlation between WNK1 expression and colon adenocarcinoma (COAD) progression.

METHODS

In the current study, WNK1 expression was evaluated by immunohistochemically in adjacent normal colonic mucosae and primary adenocarcinomas. The effect of WNK1 on overall survival (OS) and its associations with the clinicopathological parameters were analyzed in a retrospective cohort of COAD patients (n = 185). The tumor-related effects of WNK1 in COAD were further tested via cellular and mice experiments.

RESULTS

According to our cohort, higher WNK1 expression was significantly associated with unfavorable prognostic factors, such as high pT stage, pN stage, as well as shorter OS. Moreover, WNK1 exhibited tumor promoting role in COAD cancer cell lines as well as in nude mice. Silencing WNK1 can significantly inhibit the proliferation of COAD both in vitro and in vivo.

CONCLUSIONS

In all, WNK1 acts as a tumor promoter and may be used as a COAD prognostic biomarker.

ERK5 Is a Major Determinant of Chemical Sarcomagenesis: Implications in Human Pathology

Simple Summary

Sarcoma is a heterogeneous group of tumors poorly studied with few therapeutic opportunities. Interestingly, the role of MAPKs still remains unclear in sarcomatous pathology. Here, we describe for the first time the critical role of ERK5 in the biology of soft tissue sarcoma by using in vitro and in vivo approaches in a murine experimental model of chemical sarcomagenesis. Indeed, our observations were extrapolated to a short series of human leiomyosarcoma and rhabdomyosarcomas. Furthermore, transcriptome analysis allows us to demonstrate the critical role of KLF2 in the biological effects of ERK5. Therefore, the data presented here open new windows in the diagnosis and therapy of soft tissue sarcomas.

Abstract

Sarcomas are a heterogeneous group of tumors in which the role of ERK5 is poorly studied. To clarify the role of this MAPK in sarcomatous pathology, we used a murine 3-methyl-cholanthrene (3MC)-induced sarcoma model. Our data show that 3MC induces pleomorphic sarcomas with muscle differentiation, showing an increased expression of ERK5. Indeed, this upregulation was also observed in human sarcomas of muscular origin, such as leiomyosarcoma or rhabdomyosarcoma. Moreover, in cell lines derived from these 3MC-induced tumors, abrogation of Mapk7 expression by using specific shRNAs decreased in vitro growth and colony-forming capacity and led to a marked loss of tumor growth in vivo. In fact, transcriptomic profiling in ERK5 abrogated cell lines by RNAseq showed a deregulated gene expression pattern for key biological processes such as angiogenesis, migration, motility, etc., correlating with a better prognostic in human pathology. Finally, among the various differentially expressed genes, Klf2 is a key mediator of the biological effects of ERK5 as indicated by its specific interference, demonstrating that the ERK5–KLF2 axis is an important determinant of sarcoma biology that should be further studied in human pathology.

ERK5 Signalling and Resistance to ERK1/2 Pathway Therapeutics: The Path Less Travelled?

The RAS-regulated RAF-MEK1/2-ERK1/2 signalling pathway is frequently de-regulated in human cancer. Melanoma in particular exhibits a high incidence of activating BRAF^V600E/K and NRAS^Q61L/K mutations and such cells are addicted to the activity of these mutant oncoproteins. As a result three different BRAF inhibitors (BRAFi) have now been approved for BRAFV600E/K- mutant melanoma and have transformed the treatment of this disease. Despite this, clinical responses are typically transient as tumour cells develop resistance. These resistance mechanisms frequently involve reinstatement of ERK1/2 signalling and BRAFi are now deployed in combination with one of three approved MEK1/2 inhibitors (MEKi) to provide more durable, but still transient, clinical responses. Furthermore, inhibitors to ERK1/2 (ERK1/2i) have also been developed to counteract ERK1/2 signalling. However, recent studies have suggested that BRAFi/MEKi and ERK1/2i resistance can arise through activation of a parallel signalling pathway leading to activation of ERK5, an unusual protein kinase that contains both a kinase domain and a transcriptional transactivation domain. Here we review the evidence supporting ERK5 as a mediator of BRAFi/MEKi and ERK1/2i resistance. We also review the challenges in targeting ERK5 signalling with small molecules, including paradoxical activation of the transcriptional transactivation domain, and discuss new therapeutic modalities that could be employed to target ERK5.

Targeting protein kinases in cancer stem cells

Cancer stem cells (CSCs) are subpopulations of cancer cells within the tumor bulk that have emerged as an attractive therapeutic target for cancer therapy. Accumulating evidence has shown the critical involvement of protein kinase signaling pathways in driving tumor development, cancer relapse, metastasis, and therapeutic resistance. Given that protein kinases are druggable targets for cancer therapy, tremendous efforts are being made to target CSCs with kinase inhibitors. In this review, we summarize the current knowledge and overview of the roles of protein kinases in various signaling pathways in CSC regulation and drug resistance. Furthermore, we provide an update on the preclinical and clinical studies for the use of kinase inhibitors alone or in combination with current therapies for effective cancer therapy. Despite great premises for the use of kinase inhibitors against CSCs, further investigations are needed to evaluate their efficiencies without any adverse effects on normal stem cells.

Disclosing the antitumour potential of the marine bromoditerpene sphaerococcenol A on distinct cancer cellular models

Nature has revealed to be a key source of innovative anticancer drugs. This study evaluated the antitumour potential of the marine bromoditerpene sphaerococcenol A on different cancer cellular models. Dose-response analyses (0.1-100 µM; 24 h) were accomplished in eight different tumour cell lines (A549, CACO-2, HCT-15, MCF-7, NCI-H226, PC-3, SH-SY5Y, SK-MEL-28). Deeper studies were conducted on MFC-7 cells, namely, determination of hydrogen peroxide (H₂O₂) levels and evaluation of apoptosis biomarkers (phosphatidylserine membrane translocation, mitochondrial dysfunction, Caspase-9 activity, and DNA changes). The ability of the compound to induce genotoxicity was verified in L929 fibroblasts. Sphaerococcenol A capacity to impact colorectal-cancer stem cells (CSCs) tumourspheres (HT29, HCT116, SW620) was evaluated by determining tumourspheres viability, number, and area, as well as the proteasome inhibitory activity. Sphaerococcenol A hepatoxicity was studied in AML12 hepatocytes. The compound exhibited cytotoxicity in all malignant cell lines (IC₅₀ ranging from 4.5 to 16.6 µM). MCF-7 cells viability loss was accompanied by H₂O₂ generation, mitochondrial dysfunction, Caspase-9 activation and DNA nuclear morphology changes. Furthermore, the compound displayed the lowest IC₅₀ on HT29-derived tumourspheres (0.70 µM), followed by HCT116 (1.77 µM) and SW620 (2.74 µM), impacting the HT29 tumoursphere formation by reducing their number and area. Finally, the compound displayed low cytotoxicity on AML12 hepatocytes without genotoxicity. Overall, sphaerococcenol A exhibits broad cytotoxic effects on different tumour cells, increasing H₂O₂ production and apoptosis. It also affects colorectal CSCs-enriched tumoursphere development. These data highlight the relevance to include sphaerococcenol A in further pharmacological studies aiming cancer treatments.

Prolonged exposure to simulated microgravity promotes stemness impairing morphological, metabolic and migratory profile of pancreatic cancer cells: a comprehensive proteomic, lipidomic and transcriptomic analysis

Background

The impact of the absence of gravity on cancer cells is of great interest, especially today that space is more accessible than ever. Despite advances, few and contradictory data are available mainly due to different setup, experimental design and time point analyzed.

Methods

Exploiting a Random Positioning Machine, we dissected the effects of long-term exposure to simulated microgravity (SMG) on pancreatic cancer cells performing proteomic, lipidomic and transcriptomic analysis at 1, 7 and 9 days.

Results

Our results indicated that SMG affects cellular morphology through a time-dependent activation of Actin-based motility via Rho and Cdc42 pathways leading to actin rearrangement, formation of 3D spheroids and enhancement of epithelial-to-mesenchymal transition. Bioinformatic analysis reveals that SMG may activates ERK5/NF-κB/IL-8 axis that triggers the expansion of cancer stem cells with an increased migratory capability. These cells, to remediate energy stress and apoptosis activation, undergo a metabolic reprogramming orchestrated by HIF-1α and PI3K/Akt pathways that upregulate glycolysis and impair β-oxidation, suggesting a de novo synthesis of triglycerides for the membrane lipid bilayer formation.

Conclusions

SMG revolutionizes tumor cell behavior and metabolism leading to the acquisition of an aggressive and metastatic stem cell-like phenotype. These results dissect the time-dependent cellular alterations induced by SMG and pave the base for altered gravity conditions as new anti-cancer technology.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00018-022-04243-z.

Inhibition of ERK5 Elicits Cellular Senescence in Melanoma via the Cyclin-Dependent Kinase Inhibitor p21

Melanoma is the deadliest skin cancer with a very poor prognosis in advanced stages. Although targeted and immune therapies have improved survival, not all patients benefit from these treatments. The mitogen-activated protein kinase ERK5 supports the growth of melanoma cells in vitro and in vivo. However, ERK5 inhibition results in cell-cycle arrest rather than appreciable apoptosis. To clarify the role of ERK5 in melanoma growth, we performed transcriptomic analyses following ERK5 knockdown in melanoma cells expressing BRAFV600E and found that cellular senescence was among the most affected processes. In melanoma cells expressing either wild-type or mutant (V600E) BRAF, both genetic and pharmacologic inhibition of ERK5 elicited cellular senescence, as observed by a marked increase in senescence-associated β-galactosidase activity and p21 expression. In addition, depletion of ERK5 from melanoma cells resulted in increased levels of CXCL1, CXCL8, and CCL20, proteins typically involved in the senescence-associated secretory phenotype. Knockdown of p21 suppressed the induction of cellular senescence by ERK5 blockade, pointing to p21 as a key mediator of this process. In vivo, ERK5 knockdown or inhibition with XMD8-92 in melanoma xenografts promoted cellular senescence. Based on these results, small-molecule compounds targeting ERK5 constitute a rational series of prosenescence drugs that may be exploited for melanoma treatment. SIGNIFICANCE: This study shows that targeting ERK5 induces p21-mediated cellular senescence in melanoma, identifying a prosenescence effect of ERK5 inhibitors that may be exploited for melanoma treatment.

Clinical Significance and Regulation of ERK5 Expression and Function in Cancer

Extracellular signal-regulated kinase 5 (ERK5) is a unique kinase among MAPKs family members, given its large structure characterized by the presence of a unique C-terminal domain. Despite increasing data demonstrating the relevance of the ERK5 pathway in the growth, survival, and differentiation of normal cells, ERK5 has recently attracted the attention of several research groups given its relevance in inflammatory disorders and cancer. Accumulating evidence reported its role in tumor initiation and progression. In this review, we explore the gene expression profile of ERK5 among cancers correlated with its clinical impact, as well as the prognostic value of ERK5 and pERK5 expression levels in tumors. We also summarize the importance of ERK5 in the maintenance of a cancer stem-like phenotype and explore the major known contributions of ERK5 in the tumor-associated microenvironment. Moreover, although several questions are still open concerning ERK5 molecular regulation, different ERK5 isoforms derived from the alternative splicing process are also described, highlighting the potential clinical relevance of targeting ERK5 pathways.

Anticancer Activities of 9-chloro-6-(piperazin-1-yl)-11H-indeno[1,2-c] quinolin-11-one (SJ10) in Glioblastoma Multiforme (GBM) Chemoradioresistant Cell Cycle-Related Oncogenic Signatures

Simple Summary

Glioblastoma multiforme (GBM) remains to be the most frequent malignant tumor of the central nervous system (CNS), which accounts for approximately 54% of all primary brain gliomas. Current treatment modalities for GBM include surgical resection, followed by radiotherapy and chemotherapy with temozolomide (TMZ). However, due to its genetic heterogeneity, GBM tumors always recur, due to treatment reasistance. The aim of this study was to identify molecular gene signatures, responsible for cancer initiation, progression, resistances and to treatment, metastasis, and also evaluate the potency of our novel compounds SJ10 as potential target for CCNB1/CDC42/MAPK7/CD44 oncogenic signatures. Accordingly, we used computational simulation and identify these signatures as regulators of the cell cycle in GBM, which leads to cancer development and metastasis. We also showed the antiproliferative and cytotoxic effects of SJ10 compound against a panel of NCI-60 cancer cell lines. This suggests the potential of the compounds to inhibit CCNB1/CDC42/MAPK7/CD44 in GBM.

Abstract

Current anticancer treatments are inefficient against glioblastoma multiforme (GBM), which remains one of the most aggressive and lethal cancers. Evidence has shown the presence of glioblastoma stem cells (GSCs), which are chemoradioresistant and associated with high invasive capabilities in normal brain tissues. Moreover, accumulating studies have indicated that radiotherapy contributes to abnormalities in cell cycle checkpoints, including the G₁/S and S phases, which may potentially lead to resistance to radiation. Through computational simulations using bioinformatics, we identified several GBM oncogenes that are involved in regulating the cell cycle. Cyclin B1 (CCNB1) is one of the cell cycle-related genes that was found to be upregulated in GBM. Overexpression of CCNB1 was demonstrated to be associated with higher grades, proliferation, and metastasis of GBM. Additionally, increased expression levels of CCNB1 were reported to regulate activation of mitogen-activated protein kinase 7 (MAPK7) in the G₂/M phase, which consequently modulates mitosis; additionally, in clinical settings, MAPK7 was demonstrated to promote resistance to temozolomide (TMZ) and poor patient survival. Therefore, MAPK7 is a potential novel drug target due to its dysregulation and association with TMZ resistance in GBM. Herein, we identified MAPK7/extracellular regulated kinase 5 (ERK5) genes as being overexpressed in GBM tumors compared to normal tissues. Moreover, our analysis revealed increased levels of the cell division control protein homolog (CDC42), a protein which is also involved in regulating the cell cycle through the G₁ phase in GBM tissues. This therefore suggests crosstalk among CCNB1/CDC42/MAPK7/cluster of differentiation 44 (CD44) oncogenic signatures in GBM through the cell cycle. We further evaluated a newly synthesized small molecule, SJ10, as a potential target agent of the CCNB1/CDC42/MAPK7/CD44 genes through target prediction tools and found that SJ10 was indeed a target compound for the above-mentioned genes; in addition, it displayed inhibitory activities against these oncogenes as observed from molecular docking analysis.

ERK5 modulates IL-6 secretion and contributes to tumor-induced immune suppression

Tumors exhibit a variety of strategies to dampen antitumor immune responses. With an aim to identify factors that are secreted from tumor cells, we performed an unbiased mass spectrometry-based secretome analysis in lung cancer cells. Interleukin-6 (IL-6) has been identified as a prominent factor secreted by tumor cells and cancer-associated fibroblasts isolated from cancer patients. Incubation of dendritic cell (DC) cultures with tumor cell supernatants inhibited the production of IL-12p70 in DCs but not the surface expression of other activation markers which is reversed by treatment with IL-6 antibody. Defects in IL-12p70 production in the DCs inhibited the differentiation of Th1 but not Th2 and Th17 cells from naïve CD4⁺ T cells. We also demonstrate that the classical mitogen-activated protein kinase, ERK5/MAPK7, is required for IL-6 production in tumor cells. Inhibition of ERK5 activity or depletion of ERK5 prevented IL-6 production in tumor cells, which could be exploited for enhancing antitumor immune responses.

Small molecule ERK5 kinase inhibitors paradoxically activate ERK5 signalling: be careful what you wish for…

ERK5 is a protein kinase that also contains a nuclear localisation signal and a transcriptional transactivation domain. Inhibition of ERK5 has therapeutic potential in cancer and inflammation and this has prompted the development of ERK5 kinase inhibitors (ERK5i). However, few ERK5i programmes have taken account of the ERK5 transactivation domain. We have recently shown that the binding of small molecule ERK5i to the ERK5 kinase domain stimulates nuclear localisation and paradoxical activation of its transactivation domain. Other kinase inhibitors paradoxically activate their intended kinase target, in some cases leading to severe physiological consequences highlighting the importance of mitigating these effects. Here, we review the assays used to monitor ERK5 activities (kinase and transcriptional) in cells, the challenges faced in development of small molecule inhibitors to the ERK5 pathway, and classify the molecular mechanisms of paradoxical activation of protein kinases by kinase inhibitors.

Chimeric RNA ASTN2-PAPPAas aggravates tumor progression and metastasis in human esophageal cancer

Transcription-induced chimeric RNAs are an emerging area of research into molecular signatures for disease biomarker and therapeutic target development. Despite their importance, little is known for chimeric RNAs-relevant roles and the underlying mechanisms for cancer pathogenesis and progression. Here we describe a unique ASTN2-PAPPA_antisense chimeric RNA (A-P_aschiRNA) that could be the first reported chimeric RNA derived from the splicing of exons and intron antisense of two neighboring genes, respectively. Aberrant A-P_aschiRNA level in ESCC tissues was associated with tumor progression and patients' outcome. In vitro and in vivo studies demonstrated that A-P_aschiRNA aggravated ESCC metastasis and enhanced stemness through modulating OCT4. Mechanistic studies demonstrated that ERK5-mediated non-canonical PAF1 activity was required for A-P_aschiRNA-induced cancer malignancy. The study defined an undocumented function of chimeric RNAs in aggravating cancer stemness and metastasis.

The Impact of Spaceflight and Microgravity on the Human Islet-1+ Cardiovascular Progenitor Cell Transcriptome

Understanding the transcriptomic impact of microgravity and the spaceflight environment is relevant for future missions in space and microgravity-based applications designed to benefit life on Earth. Here, we investigated the transcriptome of adult and neonatal cardiovascular progenitors following culture aboard the International Space Station for 30 days and compared it to the transcriptome of clonally identical cells cultured on Earth. Cardiovascular progenitors acquire a gene expression profile representative of an early-stage, dedifferentiated, stem-like state, regardless of age. Signaling pathways that support cell proliferation and survival were induced by spaceflight along with transcripts related to cell cycle re-entry, cardiovascular development, and oxidative stress. These findings contribute new insight into the multifaceted influence of reduced gravitational environments.

In Vitro Studies on the Immunomodulatory Effects of Pulicaria crispa Extract on Human THP-1 Monocytes

Background

Pulicaria crispa (P. crispa) is a plant from the Compositae family that exhibits antioxidant, anti-inflammatory, antibacterial, and cytotoxic activities.

Objective

The current study aimed at investigating the immunomodulatory effects of P. crispa extract in lipopolysaccharide- (LPS-) stimulated human monocytic THP-1 cells.

Methods

To induce macrophage differentiation, THP-1 cell lines were treated with phorbol-12-myristate 13-acetate, followed by exposure to LPS with or without 50 or 100 μg/ml of P. crispa extract. The following tests were employed to test the immunomodulatory effects of the extract: MTT assay, ELISA, Western blotting analysis, cell migration and phagocytosis assays, and Annexin V staining method.

Results

Exposure to 100 μg/ml P. crispa extract significantly reduced THP-1 cell proliferation, migration, and phagocytosis (in LPS-stimulated cells, but not in unstimulated cells). Moreover, the extract alone significantly reduced the rate of THP-1 cell apoptosis, while it increased the rate of late apoptosis. Molecular investigations showed that treatment with P. crispa extract significantly upregulated the expression of ERK1, p-MAPK, P-P38, and Bcl2, while it significantly reduced the expression of ERK5, Bax, NF-κB, P-NF-κB, CCL1, CCL2, CCL5, CCL22, CXCL1, and CXCL10.

Conclusion

Pulicaria crispa extract exhibited anti-inflammatory, antiproliferative, antimigratory, and antiphagocytic effects in LPS-stimulated THP-1 cells. Future studies should investigate these mechanisms in animal models with chronic inflammatory diseases.

Identification and Validation of ERK5 as a DNA Damage Modulating Drug Target in Glioblastoma

Simple Summary

Glioblastomas are high-grade brain tumours and are the most common form of malignancy arising in the brain. Patient survival has improved little over the last 40 years, highlighting an urgent unmet need for more effective treatments for these tumours. Current standard-of-care treatment involves surgical removal of as much of the tumour as possible followed by a course of chemo-/radiotherapy. The main chemotherapeutic drug used is called temozolomide, however even with this treatment regimen, the average patient survival following diagnosis is around 15 months. We have identified a protein called ERK5 which is present at higher levels in these high-grade brain tumours compared to normal brain tissue, and which is also associated with resistance to temozolomide and poor patient survival. Additionally, we show that targeting ERK5 in brain tumour cells can improve the effectiveness of temozolomide in killing these tumour cells and offers potential much-needed future clinical benefit to patients diagnosed with glioblastoma.

Abstract

Brain tumours kill more children and adults under 40 than any other cancer, with approximately half of primary brain tumours being diagnosed as high-grade malignancies known as glioblastomas. Despite de-bulking surgery combined with chemo-/radiotherapy regimens, the mean survival for these patients is only around 15 months, with less than 10% surviving over 5 years. This dismal prognosis highlights the urgent need to develop novel agents to improve the treatment of these tumours. To address this need, we carried out a human kinome siRNA screen to identify potential drug targets that augment the effectiveness of temozolomide (TMZ)—the standard-of-care chemotherapeutic agent used to treat glioblastoma. From this we identified ERK5/MAPK7, which we subsequently validated using a range of siRNA and small molecule inhibitors within a panel of glioma cells. Mechanistically, we find that ERK5 promotes efficient repair of TMZ-induced DNA lesions to confer cell survival and clonogenic capacity. Finally, using several glioblastoma patient cohorts we provide target validation data for ERK5 as a novel drug target, revealing that heightened ERK5 expression at both the mRNA and protein level is associated with increased tumour grade and poorer patient survival. Collectively, these findings provide a foundation to develop clinically effective ERK5 targeting strategies in glioblastomas and establish much-needed enhancement of the therapeutic repertoire used to treat this currently incurable disease.

Recent advances in development of hetero-bivalent kinase inhibitors

Identifying a pharmacological agent that targets only one of more than 500 kinases present in humans is an important challenge. One potential solution to this problem is the development of bivalent kinase inhibitors, which consist of two connected fragments, each bind to a dissimilar binding site of the bisubstrate enzyme. The main advantage of bivalent (type V) kinase inhibitors is generating more interactions with target enzymes that can enhance the molecules' selectivity and affinity compared to single-site inhibitors. Earlier type V inhibitors were not suitable for the cellular environment and were mostly used in in vitro studies. However, recently developed bivalent compounds have high kinase affinity, high biological and chemical stability in vivo. This review summarized the hetero-bivalent kinase inhibitors described in the literature from 2014 to the present. We attempted to classify the molecules by serine/threonine and tyrosine kinase inhibitors, and then each target kinase and its hetero-bivalent inhibitor was assessed in depth. In addition, we discussed the analysis of advantages, limitations, and perspectives of bivalent kinase inhibitors compared with the monovalent kinase inhibitors.

Molecular Mechanisms of Epithelial to Mesenchymal Transition Regulated by ERK5 Signaling

Extracellular signal-regulated kinase (ERK5) is an essential regulator of cancer progression, tumor relapse, and poor patient survival. Epithelial to mesenchymal transition (EMT) is a complex oncogenic process, which drives cell invasion, stemness, and metastases. Activators of ERK5, including mitogen-activated protein kinase 5 (MEK5), tumor necrosis factor α (TNF-α), and transforming growth factor-β (TGF-β), are known to induce EMT and metastases in breast, lung, colorectal, and other cancers. Several downstream targets of the ERK5 pathway, such as myocyte-specific enhancer factor 2c (MEF2C), activator protein-1 (AP-1), focal adhesion kinase (FAK), and c-Myc, play a critical role in the regulation of EMT transcription factors SNAIL, SLUG, and β-catenin. Moreover, ERK5 activation increases the release of extracellular matrix metalloproteinases (MMPs), facilitating breakdown of the extracellular matrix (ECM) and local tumor invasion. Targeting the ERK5 signaling pathway using small molecule inhibitors, microRNAs, and knockdown approaches decreases EMT, cell invasion, and metastases via several mechanisms. The focus of the current review is to highlight the mechanisms which are known to mediate cancer EMT via ERK5 signaling. Several therapeutic approaches that can be undertaken to target the ERK5 pathway and inhibit or reverse EMT and metastases are discussed.

Breast Tumor Kinase (Brk/PTK6) Mediates Advanced Cancer Phenotypes via SH2-Domain Dependent Activation of RhoA and Aryl Hydrocarbon Receptor (AhR) Signaling

Protein tyrosine kinase 6 (PTK6; also called Brk) is overexpressed in 86% of patients with breast cancer; high PTK6 expression predicts poor outcome. We reported PTK6 induction by HIF/GR complexes in response to either cellular or host stress. However, PTK6-driven signaling events in the context of triple-negative breast cancer (TNBC) remain undefined. In a mouse model of TNBC, manipulation of PTK6 levels (i.e., via knock-out or add-back) had little effect on primary tumor volume, but altered lung metastasis. To delineate the mechanisms of PTK6 downstream signaling, we created kinase-dead (KM) and kinase-intact domain structure mutants of PTK6 via in-frame deletions of the N-terminal SH3 or SH2 domains. While the PTK6 kinase domain contributed to soft-agar colony formation, PTK6 kinase activity was entirely dispensable for cell migration. Specifically, TNBC models expressing a PTK6 variant lacking the SH2 domain (SH2-del PTK6) were unresponsive to growth factor-stimulated cell motility relative to SH3-del, KM, or wild-type PTK6 controls. Reverse-phase protein array revealed that while intact PTK6 mediates spheroid formation via p38 MAPK signaling, the SH2 domain of PTK6 limits this biology, and instead mediates TNBC cell motility via activation of the RhoA and/or AhR signaling pathways. Inhibition of RhoA and/or AhR blocked TNBC cell migration as well as the branching/invasive morphology of PTK6⁺/AhR⁺ primary breast tumor tissue organoids. Inhibition of RhoA also enhanced paclitaxel cytotoxicity in TNBC cells, including in a taxane-refractory TNBC model. IMPLICATIONS: The SH2-domain of PTK6 is a potent effector of advanced cancer phenotypes in TNBC via RhoA and AhR, identified herein as novel therapeutic targets in PTK6⁺ breast tumors.

MicroRNA-377 Counteracts With Cancer Stem Cell Phenotypes and Epithelial Mesenchymal Transformation by Targeting ZEB2 in Colon Cancer

Dysregulated microRNAs (miRNAs) have been implicated in the pathogenic processes of colon cancer. Epithelial mesenchymal transition (EMT) promotes metastatic progression and cancer stem cells are closely involved in colon cancer proliferation and metastasis. Functional effects of miR-377 on colon cancer stem cell phenotypes and EMT were then determined in the present study. Firstly, reduced miR-377 was found in colon cancer tissues and cell lines. Results from flow cytometry, sphere formation and western blot assays showed that miR-377 knockdown increased number of ALDH+ cells and promoted sphere formation ability. Moreover, cell migration/invasion and EMT of colon cancer cells were suppressed by miR-377 over-expression. On the contrary, miR-377 mimics caused the reversed results. ZEB2 (zinc finger E box-binding homeobox 2) was then validated as a binding target of miR-377. ZEB2 over-expression reversed the inhibitory abilities of miR-377 on cancer stem cell phenotypes, EMT, migration and invasion. In conclusion, miR-377 regulates cancer stem cell phenotypes and EMT in colon cancer cells via regulation of ZEB2, suggesting a new therapeutic strategy for colon cancer treatment.

GSK2593074A blocks progression of existing abdominal aortic dilation

Objective

Receptor interacting proteins kinase 1 and 3 (RIPK1 and RIPK3) have been shown to play essential roles in the pathogenesis of abdominal aortic aneurysms (AAAs) by mediating necroptosis and inflammation. We previously discovered a small molecular inhibitor GSK2593074A (GSK’074) that binds to both RIPK1 and RIPK3 with high affinity and prevents AAA formation in mice. In this study, we evaluated whether GSK’074 can attenuate progression of existing AAA in the calcium phosphate model.

Methods

C57BL6/J mice were subjected to the calcium phosphate model of aortic aneurysm generation. Mice were treated with either GSK’074 (4.65 mg/kg/day) or dimethylsulfoxide (DMSO) controls starting 7 days after aneurysm induction. Aneurysm growth was monitored via ultrasound imaging every 7 days until harvest on day 28. Harvested aortas were examined via immunohistochemistry. The impact of GSK’074 on vascular smooth muscle cells and macrophages were evaluated via flow cytometry and transwell migration assay.

Results

At the onset of treatment, mice in both the control (DMSO) and GSK’074 groups showed similar degree of aneurysmal expansion. The weekly ultrasound imaging showed a steady aneurysm growth in DMSO-treated mice. The aneurysm growth was attenuated by GSK’074 treatment. At humane killing, GSK’074-treated mice had significantly reduced progression in aortic diameter from baseline as compared with the DMSO-treated mice (83.2% ± 13.1% [standard error of the mean] vs 157.2% ± 32.0% [standard error of the mean]; P < .01). In addition, the GSK’074-treated group demonstrated reduced macrophages (F4/80, CD206, MHCII), less gelatinase activity, a higher level of smooth muscle cell-specific myosin heavy chain, and better organized elastin fibers within the aortic walls compared with DMSO controls. In vitro, GSK’074 inhibited necroptosis in mouse aortic smooth muscle cells; whereas, it was able to prevent macrophage migration without affecting Il1b and Tnf expression.

Conclusions

GSK’074 is able to attenuate aneurysm progression in the calcium phosphate model. The ability to inhibit both vascular smooth muscle cell necroptosis and macrophage migration makes GSK’074 an attractive drug candidate for pharmaceutical treatment of aortic aneurysms.

Previous clinical trials evaluating pharmaceutical treatments in blocking aneurysm progression have failed. However, most agents used in those trials focused on inhibiting only one mechanism that contributes to aneurysm pathogenesis. In this study, we found GSK’074 is able to attenuate aneurysm progression in the calcium phosphate model by inhibiting both vascular smooth muscle cell necroptosis and macrophage migration, which are both key processes in the pathogenesis of aneurysm progression. The ability of GSK’0474 to inhibit multiple key pathologic mechanisms makes it an attractive therapeutic candidate for aneurysm progression.

Potential anti-inflammatory and anti-apoptotic effect of Coccinia grandis plant extract in LPS stimulated-THP-1 cells

Coccinia grandis (C. grandis) L is an Indian medicinal plant from the Cucurbitaceae family whose extracts possess anti-oxidant, anti-infective, and anti-inflammatory properties. The objective of the present study was to probe the potential immunomodulatory of C. grandis crude extract on different pathways in THP-1 cells as probed by changes in expression of several proteins. THP-1 cells were differentiated into macrophages after treatment with phorbol-12-myristate 13-acetate, followed by exposure to lipopolysaccharide (LPS) with or without 50 or 100 μg/ml of C. grandis extract. Treatment of the cells with the extract significantly downregulated the expression and release of pro-inflammatory cytokines (IL-6, IL-1β, CCL2, CCL22, CXCL10/IP-10, CX3CL1 and CXCL8/IL-8), proteins (ERK5, BAX, BCL2, Cyclin D, ERK1, NF-κB, P-IκBα,P- NF-κB and P-p38) and molecular signaling pathways (NF-κB, p38 MAPK, ERK1/2 and IL-6/JAK/STAT3 signaling cascades). This study is the first to highlight the ability of C. grandis extract to modulate several pathways, including proliferation, the expression of inflammatory cytokines, phagocytosis, migration properties and apoptosis, in human monocytic THP-1 cells.

Regulation of Src Family Kinases during Colorectal Cancer Development and Its Clinical Implications

Src family kinases (SFKs) are non-receptor kinases that play a critical role in the pathogenesis of colorectal cancer (CRC). The expression and activity of SFKs are upregulated in patients with CRC. Activation of SFKs promotes CRC cell proliferation, metastases to other organs and chemoresistance, as well as the formation of cancer stem cells (CSCs). The enhanced expression level of Src is associated with decreased survival in patients with CRC. Src-mediated regulation of CRC progression involves various membrane receptors, modulators, and suppressors, which regulate Src activation and its downstream targets through various mechanisms. This review provides an overview of the current understanding of the correlations between Src and CRC progression, with a special focus on cancer cell proliferation, invasion, metastasis and chemoresistance, and formation of CSCs. Additionally, this review discusses preclinical and clinical strategies to improve the therapeutic efficacy of drugs targeting Src for treating patients with CRC.

Targeted Avenues for Cancer Treatment: The MEK5-ERK5 Signaling Pathway

Twenty years have passed since extracellular signal-regulated kinase 5 (ERK5) and its upstream activator, mitogen-activated protein kinase 5 (MEK5), first emerged onto the cancer research scene. Although we have come a long way in defining the liaison between dysregulated MEK5-ERK5 signaling and the pathogenesis of epithelial and nonepithelial malignancies, selective targeting of this unique pathway remains elusive. Here, we provide an updated review of the existing evidence for a correlation between aberrant MEK5-ERK5 (phospho)proteomic/transcriptomic profiles, aggressive cancer states, and poor patient outcomes. We then focus on emerging insights from preclinical models regarding the relevance of upregulated ERK5 activity in promoting tumor growth, metastasis, therapy resistance, undifferentiated traits, and immunosuppression, highlighting the opportunities, prospects, and challenges of selectively blocking this cascade for antineoplastic treatment and chemosensitization.

Antitumour Potential of Gigartina pistillata Carrageenans against Colorectal Cancer Stem Cell-Enriched Tumourspheres

Gigartina pistillata is a red seaweed common in Figueira da Foz, Portugal. Here, the antitumour potential of G. pistillata carrageenan, with a known variable of the life cycle, the female gametophyte (FG) and tetrasporophyte (T) was evaluated against colorectal cancer stem cell (CSC) -enriched tumourspheres. FTIR-ATR analysis of G. pistillata carrageenan extracts indicated differences between life cycle phases, being FG a κ/ι hybrid carrageenan and T a ʎ/ξ hybrid. Both carrageenan extracts presented IC50 values inferior to 1 μg/mL in HT29-derived CSC-enriched tumourspheres, as well as reduced tumoursphere area. The two extracts were also effective at reducing cellular viability in SW620- and SW480-derived tumourspheres. These results indicate that carrageenans extracted from two G. pistillata life cycle phases have antitumour potential against colorectal cancer stem-like cells, specially the T carrageenan.

MiR-27b targets PI3K p110α to inhibit proliferation and migration in colorectal cancer stem cell

Colorectal cancer (CRC) is one of the leading causes of cancer deaths worldwide, CRC was estimated to be the third most commonly diagnosed cancer and a leading cause of cancer deaths in developed countries due to therapy resistance and metastasis. Cancer stem cells (CSCs) were found in a variety of malignant tumors, including colorectal cancer. miR-27b play pivotal roles in the acquisition of CSC properties such as tumor initiation, drug resistance and asymmetric cell division. The aim of the present study was to investigate the underlying mechanisms that miR-27b inhibits proliferation, invasion and migration of CSCs. In present study, miR-27b were found to be significantly upregulated in CSCs. Overexpression of miR-27b inhibit CSCs proliferation and migration. In addition, overexpression of miR-27b suppress the character expression of CSCs, including of CD44, CD133, Sox2 and Oct4. Furthermore, it has been demonstrated that miR-27b is directly targeted by PIK3CA and miR-27b overexpression can effectively attenuate the expression of Phosphor-PI3K p110α and phosphor-Akt. In conclusion, these results reveal that PIK3CA is significantly downregulated by miR-27b expression in CSCs. Thus, we presume that miR-27b may be a therapeutic anti-tumor agent for CRC via targeting PI3K p110α.

Combining 1,3-Ditriazolylbenzene and Quinoline to Discover a New G-Quadruplex-Interactive Small Molecule Active against Cancer Stem-Like Cells

Quadruplex nucleic acids are promising targets for cancer therapy. In this study we used a fragment-based approach to create new flexible G-quadruplex (G4) DNA-interactive small molecules with good calculated oral drug-like properties, based on quinoline and triazole heterocycles. G4 melting temperature and polymerase chain reaction (PCR)-stop assays showed that two of these compounds are selective G4 ligands, as they were able to induce and stabilize G4s in a dose- and DNA sequence-dependent manner. Molecular docking studies have suggested plausible quadruplex binding to both the G-quartet and groove, with the quinoline module playing the major role. Compounds were screened for cytotoxicity against four cancer cell lines, where 4,4'-(4,4'-(1,3-phenylene)bis(1H-1,2,3-triazole-4,1-diyl))bis(1-methylquinolin-1-ium) (1 d) showed the greater activity. Importantly, dose-response curves show that 1 d is cytotoxic in the human colon cancer HT-29 cell line enriched in cancer stem-like cells, a subpopulation of cells implicated in chemoresistance. Overall, this study identified a new small molecule as a promising lead for the development of drugs targeting G4 in cancer stem cells.