ERK Inhibitor Research Articles

Micropeptide AF127577.4-ORF hidden in a lncRNA diminishes glioblastoma cell proliferation via the modulation of ERK2/METTL3 interaction.

Micropeptides hidden in long non-coding RNAs (lncRNAs) have been uncovered to program various cell-biological changes associated with malignant transformation-glioblastoma (GBM) cascade. Here, we identified and characterized a novel hidden micropeptide implicated in GBM. We screened potential candidate lncRNAs by establishing a workflow involving ribosome-bound lncRNAs, publicly available MS/MS data, and prognosis-related lncRNAs. Micropeptide expression was detected by western blot (WB), immunofluorescence (IF), and immunohistochemistry (IHC). Cell proliferation rate was assessed by calcein/PI staining and EdU assay. Proteins interacted with the micropeptide were analyzed by proteomics after co-immunoprecipitation (Co-IP). We discovered that lncRNA AF127577.4 indeed encoded an endogenous micropeptide, named AF127577.4-ORF. AF127577.4-ORF was associated with GBM clinical grade. In vitro, AF127577.4-ORF could suppress GBM cell proliferation. Moreover, AF127577.4-ORF reduced m6A methylation level of GBM cells. Mechanistically, AF127577.4-ORF diminished ERK2 interaction with m6A reader methyltransferase like 3 (METTL3) and downregulated phosphorylated ERK (p-ERK) level. The ERK inhibitor reduced p-ERK level and downregulated METTL3 protein expression. AF127577.4-ORF weakened the stability of METTL3 protein by ERK. Also, AF127577.4-ORF suppressed GBM cell proliferation via METTL3. Our study identifies a novel micropeptide AF127577.4-ORF hidden in a lncRNA, with a potent anti-proliferating function in GBM by diminishing METTL3 protein stability by reducing the ERK2/METTL3 interaction. This micropeptide may be beneficial for development of therapeutic strategies against GBM.

NLRX1 Mediates the Disruption of Intestinal Mucosal Function Caused by Porcine Astrovirus Infection via the Extracellular Regulated Protein Kinases/Myosin Light-Chain Kinase (ERK/MLCK) Pathway.

Porcine astrovirus (PAstV) has a potential zoonotic risk, with a high proportion of co-infection occurring with porcine epidemic diarrhea virus (PEDV) and other diarrheal pathogens. Despite its high prevalence, the cellular mechanism of PAstV pathogenesis is ill-defined. Previous proteomics analyses have revealed that the differentially expressed protein NOD-like receptor X1 (NLRX1) located in the mitochondria participates in several important antiviral signaling pathways in PAstV-4 infection, which are closely related to mitophagy. In this study, we confirmed that PAstV-4 infection significantly up-regulated NLRX1 and mitophagy in Caco-2 cells, while the silencing of NLRX1 or the treatment of mitophagy inhibitor 3-MA inhibited PAstV-4 replication. Additionally, PAstV-4 infection triggered the activation of the extracellular regulated protein kinases/ myosin light-chain kinase (ERK/MLCK) pathway, followed by the down-regulation of tight-junction proteins (occludin and ZO-1) as well as MUC-2 expression. The silencing of NLRX1 or the treatment of 3-MA inhibited myosin light-chain (MLC) phosphorylation and up-regulated occludin and ZO-1 proteins. Treatment of the ERK inhibitor PD98059 also inhibited MLC phosphorylation, while MLCK inhibitor ML-7 mitigated the down-regulation of mucosa-related protein expression induced by PAstV-4 infection. Yet, adding PD98059 or ML-7 did not affect NLRX1 expression. In summary, this study preliminarily explains that NLRX1 plays an important role in the disruption of intestinal mucosal function triggered by PAstV-4 infection via the ERK/MLC pathway. It will be helpful for further antiviral drug target screening and disease therapy.

Erk Inhibition as a Promising Therapeutic Strategy for High IL-8-Secreting and Low SPTAN1-Expressing Colorectal Cancer.

Tumor recurrence and drug resistance are responsible for poor prognosis in colorectal cancer (CRC). DNA mismatch repair (MMR) deficiency or elevated interleukin-8 (IL-8) levels are characteristics of CRCs, which have been independently correlated with treatment resistance to common therapies. We recently demonstrated significantly impaired therapeutical response and increased IL-8 release of CRC cell lines with reduced expression of MMR protein MLH1 as well as cytoskeletal non-erythrocytic spectrin alpha II (SPTAN1). In the present study, decreased intratumoral MLH1 and SPTAN1 expression in CRCs could be significantly correlated with enhanced serum IL-8. Furthermore, using stably reduced SPTAN1-expressing SW480, SW620 or HT-29 cell lines, the RAS-mediated RAF/MEK/ERK pathway was analyzed. Here, a close connection between low SPTAN1 expression, increased IL-8 secretion, enhanced extracellular-signal-regulated kinase (ERK) phosphorylation and a mesenchymal phenotype were detected. The inhibition of ERK by U0126 led to a significant reduction in IL-8 secretion, and the combination therapy of U0126 with FOLFOX optimizes the response of corresponding cancer cell lines. Therefore, we hypothesize that the combination therapy of FOLFOX and U0126 may have great potential to improve drug efficacy on this subgroup of CRCs, showing decreased MLH1 and SPTAN1 accompanied with high serum IL-8 in affected patients.

METTL7A-mediated m6A modification of corin reverses bisphosphonates-impaired osteogenic differentiation of orofacial BMSCs

Bisphosphonate-related osteonecrosis of jaw (BRONJ) is characterized by impaired osteogenic differentiation of orofacial bone marrow stromal cells (BMSCs). Corin has recently been demonstrated to act as a key regulator in bone development and orthopedic disorders. However, the role of corin in BRONJ-related BMSCs dysfunction remains unclarified. A m6A epitranscriptomic microarray study from our group shows that the CORIN gene is significantly upregulated and m6A hypermethylated during orofacial BMSCs osteogenic differentiation. Corin knockdown inhibits BMSCs osteogenic differentiation, whereas corin overexpression or soluble corin (sCorin) exerts a promotion effect. Furthermore, corin expression is negatively regulated by bisphosphonates (BPs). Corin overexpression or sCorin reverses BPs-impaired BMSCs differentiation ability. Mechanistically, we find altered expression of phos-ERK in corin knockdown/overexpression BMSCs and BMSCs under sCorin stimulation. PD98059 (a selective ERK inhibitor) blocks the corin-mediated promotion effect. With regard to the high methylation level of corin during osteogenic differentiation, we apply a non-selective m6A methylase inhibitor, Cycloleucine, which also blocks the corin-mediated promotion effect. Furthermore, we demonstrate that METTL7A modulates corin m6A modification and reverses BPs-impaired BMSCs function, indicating that METTL7A regulates corin expression and thus contributes to orofacial BMSCs differentiation ability. To conclude, our study reveals that corin reverses BPs-induced BMSCs dysfunction, and METTL7A-mediated corin m6A modification underlies corin promotion of osteogenic differentiation via the ERK pathway. We hope this brings new insights into future clinical treatments for BRONJ.

Nuclear receptor 4A1 (NR4A1) upregulated by n-butylidenephthalide via the mitogen-activated protein kinase (MAPK) pathway ameliorates drug-induced gingival enlargement.

Drug-induced gingival enlargement (DIGE) is a side effect of ciclosporin, calcium channel blockers, and phenytoin. DIGE is a serious disease that leads to masticatory and esthetic disorders, severe caries, and periodontitis but currently has no standard treatment. We recently reported that nuclear receptor 4A1 (NR4A1) is a potential therapeutic target for DIGE. This study aimed to evaluate the therapeutic effects of n-butylidenephthalide (BP), which increases the expression of NR4A1, on DIGE. In this study, NR4A1 mRNA expression was analyzed in the patients with periodontal disease (PD) and DIGE. We evaluated the effect of BP on NR4A1 expression in gingival fibroblasts and in a DIGE mouse model. RNA sequencing (RNA-seq) was conducted to identify the mechanisms by which BP increases NR4A1 expression. The results showed that NR4A1 mRNA expression in the patients with DIGE was significantly lower than the patients with PD. BP suppressed the upregulation of COL1A1 expression, which was upregulated by TGF-β. BP also ameliorated gingival overgrowth in DIGE mice and reduced Col1a1 and Pai1 expression. BP also decreased Il1β mRNA expression in gingival tissue in DIGE. RNA-seq results showed an increase in the expression of several genes related to mitogen-activated protein kinase including DUSP genes in gingival fibroblasts stimulated by BP. Treatment with ERK and JNK inhibitors suppressed the BP-induced increase in NR4A1 expression. In addition, BP promoted the phosphorylation of ERK in gingival fibroblasts. In conclusion, BP increases NR4A1 expression in gingival fibroblasts through ERK and JNK signaling, demonstrating its potential as a preventive and therapeutic agent against DIGE.

A Phase II Study of ERK Inhibition by Ulixertinib (BVD-523) in Metastatic Uveal Melanoma.

Uveal melanoma is a rare and aggressive subset of melanoma that is minimally responsive to traditional therapies. Greater than 80% of uveal melanomas have a mutation in GNAQ or GNA11 which lead to downstream signaling through the MAPK pathway. Ulixertinib (BVD-523) is a potent and reversible small-molecule ATP-competitive inhibitor of both ERK1 and ERK2 protein kinases. We performed a phase II study to determine the efficacy and safety of BVD-523 in patients with metastatic uveal melanoma. This was conducted as a Simon two-stage design with a sample size of 25 patients and an initial evaluation of efficacy after 13 patients. From April 2018 to April 2019, 13 patients were enrolled. Patients were predominantly female (69%) with a median age of 64 years (34-76). Sites of metastases included liver (84.6%) and lung (30.8%). Grade 3 and 4 toxicities associated with therapy were consistent with ERK inhibitors and included liver function test (LFT) elevation, hyponatremia, pruritis, amylase elevation, anemia, and rash. The best response, per RECIST 1.1, was stable disease in 4 patients, and disease progression in 7 patients. Two patients were unevaluable for response due to withdrawal from study. Median time to progression was 2.0 months. There were eight deaths due to disease progression with a median overall survival of 6.9 months. ERK inhibition with ulixertinib (BVD-523) did not demonstrate activity in patients with metastatic uveal melanoma. The toxicities observed were consistent with what would be expected with MAPK pathway inhibition. Uveal melanoma is a difficult to treat disease with minimal therapy options. The majority of uveal melanomas have mutations in GNAQ or GNA11 leading to activation of the MAPK pathway. Efforts to target MEK in uveal melanoma has had mixed results. This phase II trial of ERK inhibition with BVD-523 examined the potential role of this agent in uveal melanoma therapy.

Mitochondrial antiviral signaling protein enhances MASLD progression via the ERK/TNFα/NFκβ pathway.

Background and Aims: Mitochondrial antiviral signaling protein (MAVS) is a critical regulator that activates the host’s innate immunity against RNA viruses, and its signaling pathway has been linked to the secretion of proinflammatory cytokines. However, the actions of MAVS on inflammatory pathways during the development of metabolic dysfunction–associated steatotic liver disease (MASLD) have been little studied. Approach and Results: Liver proteomic analysis of mice with genetically manipulated hepatic p63, a transcription factor that induces liver steatosis, revealed MAVS as a target downstream of p63. MAVS was thus further evaluated in liver samples from patients and in animal models with MASLD. Genetic inhibition of MAVS was performed in hepatocyte cell lines, primary hepatocytes, spheroids, and mice. MAVS expression is induced in the liver of both animal models and people with MASLD as compared with those without liver disease. Using genetic knockdown of MAVS in adult mice ameliorates diet-induced MASLD. In vitro, silencing MAVS blunts oleic and palmitic acid–induced lipid content, while its overexpression increases the lipid load in hepatocytes. Inhibiting hepatic MAVS reduces circulating levels of the proinflammatory cytokine TNFα and the hepatic expression of both TNFα and NFκβ. Moreover, the inhibition of ERK abolished the activation of TNFα induced by MAVS. The posttranslational modification O-GlcNAcylation of MAVS is required to activate inflammation and to promote the high lipid content in hepatocytes. Conclusions: MAVS is involved in the development of steatosis, and its inhibition in previously damaged hepatocytes can ameliorate MASLD.

17β-estradiol induces hyperresponsiveness in guinea pig airway smooth muscle by inhibiting the plasma membrane Ca2+-ATPase

High serum estrogen concentrations are associated with asthma development and severity, suggesting a link between estradiol and airway hyperresponsiveness (AHR). 17β-estradiol (E2) has non-genomic effects via Ca2+ regulatory mechanisms; however, its effect on the plasma membrane Ca2+-ATPases (PMCA1 and 4) and sarcoplasmic reticulum Ca2+-ATPase (SERCA) is unknown. Hence, in the present study, we aim to demonstrate if E2 favors AHR by increasing intracellular Ca2+ concentrations in guinea pig airway smooth muscle (ASM) through a mechanism involving Ca2+-ATPases.In guinea pig ASM, Ca2+ microfluorometry, muscle contraction, and Western blot were evaluated. Then, we performed molecular docking analysis between the estrogens and Ca2+ ATPases.In tracheal rings, E2 produced AHR to carbachol. In guinea pig myocytes, acute exposure to physiological levels of E2 modified the transient Ca2+ peak induced by caffeine to a Ca2+ plateau. The incubation with PMCA inhibitors (lanthanum and carboxyeosin, CE) partially reversed the E2-induced sustained plateau in the caffeine response. In contrast, cyclopiazonic acid (SERCA inhibitor), U-0126 (an inhibitor of ERK 1/2), and choline chloride did not modify the Ca2+ plateau produced by E2. The mitochondrial uniporter activity and the capacitative Ca2+ entry were unaffected by E2. In guinea pig ASM, Western blot analysis demonstrated PMCA1 and PMCA4 expression. The results from the docking modeling demonstrate that E2 binds to both plasma membrane ATPases. In guinea pig tracheal smooth muscle, inhibiting the PMCA with CE, induced hyperresponsiveness to carbachol. 17β-estradiol produces hyperresponsiveness by inhibiting the PMCA in the ASM and could be one of the mechanisms responsible for the increase in asthmatic crisis in women.

Regulation of macrophage polarization and glucose metabolism by the ERK/MAPK-HK1 signaling pathway in paraquat-induced acute lung injury

Acute lung injury is the leading cause of paraquat (PQ) poisoning-related mortality. The mechanism by which macrophages are involved in PQ-induced acute lung injury remains unclear. In recent years, the role of metabolic reprogramming in macrophage functional transformation has received significant attention. The current study aimed to identify the role of altered macrophage glucose metabolism and molecular mechanisms in PQ poisoning-induced acute lung injury. We established a model of acute lung injury in PQ-intoxicated mice via the intraperitoneal injection of PQ. PQ exposure induces macrophage M1 polarization and promotes the release of inflammatory factors, which causes the development of acute lung injury in mice. In vitro analysis revealed that PQ altered glucose metabolism, which could be reversed by siRNA transfection to silence the expression of HK1, a key enzyme in glucose metabolism. RNA sequencing revealed that the ERK/MAPK pathway was the crucial molecular mechanism of PQ pathogenesis. Further, U0126, an ERK inhibitor, could inhibit PQ-induced HK1 activation and macrophage M1 polarization. These findings provide novel insights into the previously unrecognized mechanism of ERK/MAPK-HK1 activation in PQ poisoning.

HER3 V104 mutations regulate cell signaling, growth, and drug sensitivity in cancer.

HER3 is mutated in ~2%-10% of cancers depending on the cancer type. We found the HER3-V104L mutation to be activating from patient-derived mutations introduced via lentiviral transduction in HER3KO HER2 + HCC1569 breast cancer cells in which endogenous HER3 was eliminated by CRISPR/Cas9. Cells expressing HER3-V104L showed higher p-HER3 and p-ERK1/2 expression versus cells expressing wild-type HER3 or HER3-V104M. Patients whose tumor expressed the HER3 V104L variant had a reduced probability of overall survival compared to patients lacking a HER3 mutation whereas we did not find a statistically significant difference in overall survival of various cancer patients with the HER3 V104M mutation. Our data showed that HER2 inhibitors suppressed cell growth of HCC1569HER3KO cells stably expressing the HER3-V104L mutation. Cancer cell lines (SNU407, UC15 and DV90) with endogenous HER3-V104M mutation showed reduced cell proliferation and p-HER2/p-ERK1/2 expression with HER2 inhibitor treatment. Knock down of HER3 abrogated cell proliferation in the above cell lines which were overall more sensitive to the ERK inhibitor SCH779284 versus PI3K inhibitors. HER3-V104L mutation stabilized HER3 protein expression in COS7 and SNUC5 cells. COS7 cells transiently transfected with the HER3-V104L mutation in the presence of HER binding partners showed higher expression of p-HER3, p-ERK1/2 versus HER3-WT in a NRG-independent manner without any change in AKT signaling. Overall, this study shows the clinical relevance of the HER3 V104L and the V104M mutations and its response to HER2, PI3K and ERK inhibitors.

TLR2-ERK signaling pathway regulates expression of galectin-3 in a murine model of OVA-induced allergic airway inflammation

Toll-like receptor 2 (TLR2) and galectin-3 (Gal-3) are involved in the pathological process of asthma, but the underlying mechanism is not fully understood. We hypothesized that TLR2 pathway may regulate expression of Gal-3 in allergic airway inflammation. Wild-type (WT) and TLR2−/− mice were sensitized on day 0 and challenged with ovalbumin (OVA) on days 14–21 to establish a model of allergic airway inflammation, and were treated with a specific ERK inhibitor U0126. Histological changes in the lungs were analyzed by hematoxylin-eosin (HE) and Periodic Acid-Schiff (PAS) staining; cytokines and anti-OVA immunoglobulin E (IgE) were tested by ELISA; and related protein expression in lung tissues was measured by western blot. We found that the expression levels of TLR2 and Gal-3 markedly increased concomitantly with airway inflammation after OVA induction, while TLR2 deficiency significantly alleviated airway inflammation and reduced Gal-3 expression. Moreover, the expression levels of phosphorylated mitogen-activated protein kinases (p-MAPKs) were significantly elevated in OVA-challenged WT mice, while TLR2 deficiency only significantly decreased phosphorylated extracellular signal-regulated kinase (p-ERK) levels. Furthermore, we found that U0126 treatment significantly alleviated allergic airway inflammation and decreased Gal-3 levels in OVA-challenged WT mice, but had no further effect in OVA-challenged TLR2−/− mice. These above results suggested that TLR2 is an upstream signal molecule of ERK. We further demonstrated that TLR2 regulates Gal-3 expression through the ERK pathway in LTA-stimulated macrophages in vitro. Our findings showed that the TLR2-ERK signaling pathway regulates Gal-3 expression in a murine model of allergic airway inflammation.

The ERK inhibitor GDC-0994 selectively inhibits growth of BRAF mutant cancer cells

BRAF or RAS mutation-induced aberrant activation of the mitogen-activated protein kinase (MAPK) pathway is frequently observed in human cancers. As the key downstream node of MAPK pathway, ERK1/2 is as an important therapeutic target. GDC-0994 (ravoxertinib), an orally bioavailable, highly selective small-molecule inhibitor of ERK1/2, showed acceptable safety and pharmacodynamic profile in a recent phase I clinical trial. In this study, we investigated dependence of the anti-tumor effect of ERK inhibitor GDC-0994 on genetic alterations in the MAPK pathway. The results showed that GDC-0994 sharply inhibited cell proliferation and colony formation and induced remarkable G1 phase cell-cycle arrest in cancer cells harboring BRAF mutation but had little effect on cell behaviors in most RAS mutant or wild-type cell lines. The expression of a large number of genes, particularly the genes in the cell cycle pathway, were significantly changed after GDC-0994 treatment in BRAF mutant cells, while no remarkable expression change of such genes was observed in wild-type cells. Moreover, GDC-0994 selectively inhibited tumor growth in a BRAF mutant xenograft mice model. Our findings demonstrate a BRAF mutation-dependent anti-tumor effect of GDC-0994 and provide a rational strategy for patient selection for ERK1/2 inhibitor treatment.

Latent-Transforming Growth Factor β-Binding Protein 1/Transforming Growth Factor β1 Complex Drives Antitumoral Effects upon ERK5 Targeting in Melanoma

Melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. Available treatments have improved the survival, although long-term benefits are still unsatisfactory. The mitogen-activated protein kinase ERK5 promotes melanoma growth, and ERK5 inhibition determines cellular senescence and the senescence-associated secretory phenotype. Here, latent-transforming growth factor β-binding protein 1 (LTBP1) mRNA was found to be upregulated in A375 and SK-Mel-5 BRAFV600E melanoma cells after ERK5 inhibition. In keeping with a key role of LTBP1 in regulating transforming growth factor β (TGF-β), TGF-β1 protein levels were increased in lysates and conditioned media of ERK5-knock down (KD) cells, and were reduced upon LTBP1 KD. Both LTBP1 and TGF-β1 proteins were increased in melanoma xenografts in mice treated with the ERK5 inhibitor XMD8-92. Moreover, treatment with conditioned media from ERK5-KD melanoma cells reduced cell proliferation and invasiveness, and TGF-β1-neutralizing antibodies impaired these effects. In silico datasets revealed that higher expression levels of both LTBP1 and TGFB1 mRNA are associated with better overall survival of melanoma patients, and that increased LTBP1 or TGF-β1 expression proved a beneficial role in patients treated with anti-PD1 immunotherapy, making unlikely a possible immunosuppressive role of LTBP1/TGF-β1 upon ERK5 inhibition. This study, therefore, identifies additional desirable effects of ERK5 targeting, providing evidence of an ERK5-dependent tumor suppressive role of TGF-β in melanoma.

Cornus officinalis Sieb. Et Zucc. attenuates Aβ25–35-induced mitochondrial damage and neuroinflammation in mice by modulating the ERK pathway

BackgroundCornus officinalis Sieb. Et Zucc. has the efficacy of tonifying the marrow and filling up the essence, breaking up the accumulation and opening up the orifices. Our research team found that CoS extracts were protective against Aβ25–35-induced memory impairment in mice. However, the pharmacodynamic components and mechanisms by which CoS improves AD have yet to be thoroughly explored and investigated. PurposeThis study focused on exploring the bioactive components and pharmacodynamic mechanisms of CoS aqueous extract underlying mitochondrial damage and neuroinflammation to improve Aβ25–35-induced AD. MethodsAD mouse models were generated using Aβ25–35 brain injections. Different doses of CoS aqueous extract were orally administered to mice for 28 days. The cognitive function, neuronal and synaptic damage, mitochondrial damage (mitochondrial length, mitochondrial fusion fission-related protein expression), neuroglial activation, and immune inflammatory factor and ERK pathway-related protein levels of mice were assessed. The CoS aqueous extracts components were identified using UPLC-TQ/MS and screened for cellular activity. Midivi-1 (Drp1 inhibitor) or PD98059 (ERK inhibitor) was added to Aβ25–35-exposed PC12 cells to assess whether CoS and its active compounds mMorB and CorE regulate mitochondrial fission through ERK/Drp1. PC12-N9 cells were cocultured to investigate whether mMorB and CorE could regulate mitochondrial division through the ERK pathway to modulate neuroinflammation. ResultsCoS improved exploration and memory in AD mice, reduced synaptic and mitochondrial damage in their hippocampus, and modulated disturbed mitochondrial dynamics. Moreover, CoS inhibited ERK pathway signaling and attenuated abnormal activation of glial cells and secondary immune inflammatory responses. Additionally, in vitro experiments revealed that CoS and its compounds 7β-O-methylmorroniside (mMorB) and Cornusdiridoid E (CorE) ameliorated mitochondrial injury caused by Aβ25–35 in PC12 cells through inhibition of the ERK/Drp1 pathway. Meanwhile, mMorB and CorE ameliorated cellular inflammation by inhibiting the Ras/ERK/CREB signaling pathway. ConclusionCoS aqueous extract ameliorates behavioral deficits and brain damage in Aβ25–35-induced AD mice by modulating the ERK pathway to attenuate mitochondrial damage and neuroinflammation, and the compounds mMorB and CorE are the therapeutically active ingredients.

MUC1 promotes cervical squamous cell carcinoma through ERK phosphorylation-mediated regulation of ITGA2/ITGA3

In contrast to the decreasing trends in developed countries, the incidence and mortality rates of cervical squamous cell carcinoma in China have increased significantly. The screening and identification of reliable biomarkers and candidate drug targets for cervical squamous cell carcinoma are urgently needed to improve the survival rate and quality of life of patients. In this study, we demonstrated that the expression of MUC1 was greater in neoplastic tissues than in non-neoplastic tissues of the cervix, and cervical squamous cell carcinoma patients with high MUC1 expression had significantly worse overall survival than did those with low MUC1 expression, indicating its potential for early diagnosis of cervical squamous cell carcinoma. Next, we explored the regulatory mechanism of MUC1 in cervical squamous cell carcinoma. MUC1 could upregulate ITGA2 and ITGA3 expression via ERK phosphorylation, promoting the proliferation and metastasis of cervical cancer cells. Further knockdown of ITGA2 and ITGA3 significantly inhibited the tumorigenesis of cervical cancer cells. Moreover, we designed a combination drug regimen comprising MUC1-siRNA and a novel ERK inhibitor in vivo and found that the combination of these drugs achieved better results in animals with xenografts than did MUC1 alone. Overall, we discovered a novel regulatory pathway, MUC1/ERK/ITGA2/3, in cervical squamous cell carcinoma that may serve as a potential biomarker and therapeutic target in the future.

Abstract PS12-07: Phase II clinical trial of palbociclib and binimetinib in advanced triple-negative breast cancer (TNBC) with hyperactivation of ERK and/or CDK4/6

Abstract Background: We previously demonstrated that a kinase-based taxonomy of TNBC was most parsimonious than next-generation sequencing in defining TNBC subtypes associated with prognostic categories in early disease. The most aggressive TNBC variants were driven by a heterogeneous set of genetic aberrations that converged in the increased activity of 6 kinases: KIT, PNKP, PRKCE, P70S6K, ERK and CDK6 (Nat Commun; 9:3501-18). The combined inhibition of these kinases in pairs led to potent tumor regression in preclinical models, being the most powerful combination that one directed against CDK6 and ERK. This prompted us to design a phase II trial testing the combination of palbociclib (against CDK6) and binimetinib (against the ERK upstream kinase MEK, since no ERK inhibitor was available at that moment outside phase I trials) in advanced TNBC. Hyperactivation of CDK6 and/or ERK was selected as entry criterion. Trial design: This was a single-arm, prospective, multicentric, open-label, phase II investigator-initiated trial. CDK6 and phosphor-ERK levels were measured in tumor samples by immunohistochemistry and normalized with a reference sample collection to a Z-score. Patients with scores for either kinase above the median were candidates for the trial. Key inclusion criteria included metastatic >18year-old TNBC, adequate organ function, measurable disease, and progression to 1-2 prior treatment lines (including immunotherapy, and a PARP inhibitor in case of germline BRCA1/2 mutation). Patients started continuous oral binimetinib at 45 mg/BID and palbociclib 100 mg/day from days 1 to 21, in 28-day cycles. Patients experiencing ≤ grade 1 tolerable side effects as the greatest toxicity were escalated to palbociclib to 125 in cycle 2. RECIST 1.1 and NCI CTC AE V 5.0 were used for assessing disease control (q8 weeks) and toxicity. The primary aims were to assess the efficacy and toxicity of this combination, and the secondary one to detect biomarkers of activity. At the time of trial design, in absence of available Sacituzumab for prescription, the reference PFS to beat in advanced lines for physician’s choice in TNBC was 1.7 month (NEJM; 384:1529-41, 2021). With alpha and beta errors of 0.05 and 0.2, the minimum number of patients to demonstrate a 30% improvement in PFS to 2.5 months was 25. Results: From November 2020 to April 2023, 69 patients were screened and 24 entered the trial (5 positive for phosphor-ERK; 2 for CDK6; 17 for both). Toxicity was generally mild and included grade 1-2 diarrhea (33% of the patients), grade 1-2 asthenia (50%), grade 1-3 neutropenia (75%), grade 2 retinal toxicity (8.3%) and grade 3 rash (4.2%); no grade 4/5 toxicities were observed. Median PFS was 1.83 months (range 0.3 to 11.3+). Phospho-ERK and CDK6 levels were not correlated (Pearson’s R= -0.089; P=0.68); CDK6 levels did not show association with PFS time (R = -0.120; P=0.58). Interestingly, however, phosphor-ERK levels in the baseline tumor sample showed correlation with PFS time (R = 0.428; P=0.037). Conclusion: The combination of palbociclib and binimetinib was generally safe, and PFS time showed correlation with baseline phosphorylation levels of ERK. However, the trial did not meet its primary endpoint. Citation Format: Rodrigo Sánchez-Bayona, Alfonso Cortes, Juan Miguel Cejalvo, Luis Manso, Serafin Morales, Jose A Garcia-Saenz, Jorge Silva, Juan A Guerra, Diego Malón-Giménez, Silvana Mouron, Eduardo Caleiras, Miguel Quintela-Fandino. Phase II clinical trial of palbociclib and binimetinib in advanced triple-negative breast cancer (TNBC) with hyperactivation of ERK and/or CDK4/6 [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS12-07.

Abstract PO4-23-09: Dual inhibition of FGFR4 and HER2/EGFR with Lapatinib improves targeting of Erk and Akt signaling in HER2+ breast cancer cells

Abstract In HER2-enriched (HER2E) breast cancer (BC), the dual HER2/EGFR inhibitor Lapatinib is a standard of care for advanced staged disease. Anti-HER2 therapies disrupt tumor progression through inhibition of the PI3K/AKT pathway. Some treated tumors will override inhibition by shifting to MAPK/ERK signaling to fuel cell growth, thus fostering resistance to anti-HER2 therapy. The tyrosine receptor kinase FGFR4 is included in the profile for a HER2E subtype. FGFR4 is overexpressed in ~30% of BC and can signal through PI3K/AKT and MAPK/ERK. Inhibitors for FGFR4 such as BLU554 are being investigated in phase I/II clinical trials for hepatocellular carcinoma, showing success in tumors that are positive for FGFR4’s preferred ligand FGF19. According to cBioPortal patient data, FGF19 is amplified in ~20% of BC, and has been shown to trigger an autocrine loop in triple negative BC through FGFR4. We examined BLU554 as a dual therapeutic with Lapatinib and dissected intracellular signaling stemming from the combination in HER2E BC. MDA-MB-453 BC cells (HER2+FGFR4+) were used for a dual strategy with BLU554 and Lapatinib. Cell viability assays were performed at matched doses, then as a dose response matrix, ranging from 0.1-20 µM. Findings were used for synergy analysis using synergyfinder.fimm.fi. Western blots determined protein activity in response to treatments. Ridaforolimus (mTOR inhibitor) was used in combination with either BLU554 or Lapatinib to assess MAPK/ERK and PI3K/AKT pathway crosstalk in MB-453 cells. Additionally, FGF19 was added to cells after a 2-hour pre-treatment to challenge BLU554 + Lapatinib and compare changes in signaling with FGF19 present. MB-453 cells treated with BLU554 decreased cell viability similarly to Lapatinib at 10 µM (65% [SD ± 3.3] and 63% [SD ± 2.1], respectively). Dual treatment decreased viability compared to single agents at all concentrations but the greatest difference was observed at 20 µM (38.5% in dual compared to Lapatinib [p-value = 0.00006]; 45.1% in dual compared to BLU554 [p-value = 0.00016]). Dose-response matrix of dual treatment yielded a ZIP synergy score of 16.852 ± 2.97 (>10 is synergistic), with the greatest synergy and inhibition at 10 µM and 20 µM of both drugs. BLU554 caused a therapeutic potency shift of Lapatinib, such that lower doses of Lapatinib (0.1 µM, 1 µM) are effective at higher doses of BLU554 (10 µM, 20 µM). Westerns of MB-453 with one dose of BLU554 increased phospho-ERK1/2 (pERK1/2) at 16- or 48-hr time points versus control, but when BLU554 was re-dosed then pERK1/2 was successfully inhibited. Both pAKT and pS6RP were increased by re-dosing BLU554. Cells treated for 2 hrs with Lapatinib decreased pAKT and pS6RP and did not change pERK, whereas a 2-hr treatment of BLU554 increased pAKT and decreased pERK. Dual treatment exhibited inhibition of ERK, AKT, 4EBP1, and S6RP phosphorylation all to a greater extent than single agents in combination with Ridaforolimus. Challenge by ectopic FGF19 of BLU554 + Lapatinib was unable to restore downstream signaling of AKT and ERK. BLU554 synergistically interacts with Lapatinib to decrease cell viability while increasing its therapeutic potency. Lapatinib primarily inhibits AKT signaling, whereas BLU554 targets ERK. Dual treatment simultaneously blocks MAPK/ERK and PI3K/AKT signaling and yields decreases of mTOR downstream effectors pS6RP and p4EBP1. These effects are maintained even when challenged with FGF19, suggesting that dual inhibition of FGFR4 and HER2 could prevent pathway activation from external stimuli. Citation Format: Jordan Beardsley, Joseph Goode, Deborah Altomare. Dual inhibition of FGFR4 and HER2/EGFR with Lapatinib improves targeting of Erk and Akt signaling in HER2+ breast cancer cells [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-23-09.

TCF19 promotes cell proliferation and tumor formation in lung cancer by activating the Raf/MEK/ERK signaling pathway

ObjectiveThis study aimed to investigate TCF19′s role in lung cancer development, specifically its involvement in the RAF/MEK/ERK signaling pathway. MethodsLung cancer tissue analysis revealed significant TCF19 overexpression. In vitro experiments using A549 and Hop62 cells with TCF19 overexpression demonstrated enhanced cell growth. Transgenic mouse models confirmed TCF19′s role in primary tumor development. Transcriptome sequencing identified altered gene expression profiles, linking TCF19 to RAF/MEK/ERK pathway activation. Functional assays elucidated underlying mechanisms, revealing increased phosphorylation of Raf1, MEK1/2, and ERK1/2. Inhibiting RAF1 or ERK through shRaf1 or ERK inhibitor reduced cell cycle-related proteins and inhibited TCF19-overexpressing cell growth. ResultsTCF19 was identified as an oncogene in lung carcinoma, specifically impacting the RAF/MEK/ERK pathway. Elevated TCF19 levels in lung cancer suggest targeting TCF19 or its associated pathways as a promising strategy for disease management. ConclusionThis study unveils TCF19′s oncogenic role in lung cancer, emphasizing its modulation of the RAF/MEK/ERK pathway and presenting a potential therapeutic target for TCF19-overexpressing lung cancers.

Internalized β2-Adrenergic Receptors Inhibit Subcellular Phospholipase C-Dependent Cardiac Hypertrophic Signaling

Chronic overstimulation of Gs-coupled b-adrenergic receptor (b-AR) signaling by catecholamines, induces pathological cardiac hypertrophy and ultimately heart failure. b1-ARs and b2-ARs are the two major subtypes of b-ARs present in the human heart and mediate the activity of sympathetic nervous system. It is known that b1-ARs and b2-ARs elicit significantly different or even opposite effects on cardiac functions such as contractility and heart failure, though they share overall sequence and structural homology, and both stimulate cAMP production. The molecular mechanisms underlying these distinct biological effects have not been fully elucidated. Previously, our laboratory demonstrated that a cAMP/EPAC/phospholipase Ce (PLCe)-mediated signaling pathway at the Golgi apparatus is important for regulation of cardiac hypertrophy. We also showed that this pathway is selectively stimulated by activation of b1-ARs localized at Golgi apparatus but not those at the plasma membrane (PM). Access to intracellular b1-ARs by catecholamines was mediated by the organic cation transporters (OCTs), and blockade of OCT3 inhibited catecholamine stimulated cardiomyocyte hypertrophy. In my current study using adult ventricular cardiac myocytes, I found that the activation of endosomal b2-ARs opposes stimulation of the prohypertrophic EPAC/PLCe pathway at the Golgi apparatus by either Angiotensin II (ATII), or the activation of Golgi localized b1-ARs by Dobutamine (Dob). b2-AR-dependent inhibition is at the level of PLCe since activation of b2-AR with salmeterol (Sal) blocks direct activation of EPAC/PLCe by the EPAC selective cAMP analog 8-(4-chlorophenylthio)-2′- O-methyl-cAMP (CPTOMe)-AM, and blocks PLCe activation by ATII which activates PLCe through a pathway that does not rely on EPAC. Blockade of internalization of b2-ARs with Dyngo-4A abolished this inhibitory signaling. Downstream of b2-ARs, I found that b2-AR-dependent PLCe inhibition is not mediated by PKA. Rather, blockade of Gi with PTX, or Gbg with gallein, inhibited the ability of b2-ARs to block Golgi PLCe activity. Additionally, inhibition of ERK activation by PD0325901 abolished b2-AR-mediated inhibition of Golgi PLCe activity. This supports a model where b2ARs internalized from the plasma membrane activate Gi releasing Gbg subunits leading to ERK activation and inhibition of PI hydrolysis at the Golgi apparatus, thereby inhibiting hypertrophic signaling by PLCe. In addition, we also showed PKD and HDAC phosphorylation downstream of PLCe signaling are significantly attenuated by b2ARs activation in mouse hearts. Consistent with the results from mice, b2ARs activation by Sal blunted cellular hypertrophy induced by b1-ARs activation by Dob in vitro measured by cell area and the expression of the hypertrophic marker, atrial natriuretic factor (ANF). Importantly, inhibition endosomal Gbg using a highly selective Gbg inhibitor (GRK2CT) fused to an endosomal targeting sequence (FYVE domain) prevent Sal mediated protective signaling in hypertrophy measurements in vitro. This indicates the inhibitory signaling downstream of b2ARs is indeed driven by endosomal Gbg. This study reveals a novel potential mechanism for b2-AR antagonism of the Epac/PLCe pathway that may contribute to the known protective effects of b2AR signaling on the development of heart failure. Elucidation of a mechanism for the anti-hypertrophic versus hypertrophic signaling balance from b1-ARs and b2-ARs gives critical insights into the development of new strategies for treatment of heart failure by targeting bAR subtypes. This work is supported by grant R35 GM127303-01 (A.V.S.). Preprint: https://www.biorxiv.org/content/10.1101/2023.06.07.544153v1. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cyclic strain alters the transcriptional and migratory response of scleral fibroblasts to TGFβ

In glaucoma, scleral fibroblasts are exposed to IOP-associated mechanical strain and elevated TGFβ levels. These stimuli, in turn, lead to scleral remodeling. Here, we examine the scleral fibroblast migratory and transcriptional response to these stimuli to better understand mechanisms of glaucomatous scleral remodeling. Human peripapillary scleral (PPS) fibroblasts were cultured on parallel grooves, treated with TGFβ (2 ng/ml) in the presence of vehicle or TGFβ signaling inhibitors, and exposed to uniaxial strain (1 Hz, 5%, 12–24 h). Axis of cellular orientation was determined at baseline, immediately following strain, and 24 h after strain cessation with 0° being completely aligned with grooves and 90° being perpendicular. Fibroblasts migration in-line and across grooves was assessed using a scratch assay. Transcriptional profiling of TGFβ-treated fibroblasts with or without strain was performed by RT-qPCR and pERK, pSMAD2, and pSMAD3 levels were measured by immunoblot. Pre-strain alignment of TGFβ-treated cells with grooves (6.2 ± 1.5°) was reduced after strain (21.7 ± 5.3°, p < 0.0001) and restored 24 h after strain cessation (9.5 ± 2.6°). ERK, FAK, and ALK5 inhibition prevented this reduction; however, ROCK, YAP, or SMAD3 inhibition did not. TGFβ-induced myofibroblast markers were reduced by strain (αSMA, POSTN, ASPN, MLCK1). While TGFβ-induced phosphorylation of ERK and SMAD2 was unaffected by cyclic strain, SMAD3 phosphorylation was reduced (p = 0.0004). Wound healing across grooves was enhanced by ROCK and SMAD3 inhibition but not ERK or ALK5 inhibition. These results provide insight into the mechanisms by which mechanical strain alters the cellular response to TGFβ and the potential signaling pathways that underlie scleral remodeling.