Receptor Kinase Activity Research Articles

Neuroprotective potentials of Lead phytochemicals against Alzheimer's disease with focus on oxidative stress-mediated signaling pathways: Pharmacokinetic challenges, target specificity, clinical trials and future perspectives

BackgroundAlzheimer's diseases (AD) and dementia are among the highly prevalent neurological disorders characterized by deposition of beta amyloid (Aβ) plaques, dense deposits of highly phosphorylated tau proteins, insufficiency of acetylcholine (ACh) and imbalance in glutamatergic system. Patients typically experience cognitive, behavioral alterations and are unable to perform their routine activities. Evidence also suggests that inflammatory processes including excessive microglia activation, high expression of inflammatory cytokines and release of free radicals. Thus, targeting inflammatory pathways beside other targets might be the key factors to control- disease symptoms and progression. PurposeThis review is aimed to highlight the mechanisms and pathways involved in the neuroprotective potentials of lead phytochemicals. Further to provide updates regarding challenges associated with their use and their progress into clinical trials as potential lead compounds. MethodsMost recent scientific literature on pre-clinical and clinical data published in quality journals especially on the lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin was collected using SciFinder, PubMed, Google Scholar, Web of Science, JSTOR, EBSCO, Scopus and other related web sources. ResultsLiterature review indicated that the drug discovery against AD is insufficient and only few drugs are clinically approved which have limited efficacy. Among the therapeutic options, natural products have got tremendous attraction owing to their molecular diversity, their safety and efficacy. Research suggest that natural products can delay the disease onset, reduce its progression and regenerate the damage via their anti-amyloid, anti-inflammatory and antioxidant potentials. These agents regulate the pathways involved in the release of neurotrophins which are implicated in neuronal survival and function. Highly potential lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin regulate neuroprotective signaling pathways implicated in neurotrophins-mediated activation of tropomyosin receptor kinase (Trk) and p75 neurotrophins receptor (p75NTR) family receptors. ConclusionsPhytochemicals especially phenolic compounds were identified as highly potential molecules which ameliorate oxidative stress induced neurodegeneration, reduce Aβ load and inhibit vital enzymes. Yet their clinical efficacy and bioavailability are the major challenges which need further interventions for more effective therapeutic outcomes.

Profiling of secondary metabolite and evaluation of anti-diabetic potency of Crotalaria quinquefolia (L): In-vitro, in-vivo, and in-silico approaches

Traditional medicinal plants have played a promising role in the human health system. In folklore medicine, Crotalaria quinquefolia L. is used to treat fever, pain, eczema, impetigo, lung infections, scabies. The present investigation was executed to identify secondary metabolites responsible for anti-diabetic potential of C. quinquefolia L. leaf extract along with their possible mechanistic pathways. The anti-hyperglycemic activity was assessed by in vitro α-amylase and α-glucosidase inhibitory assays and an in vivo oral glucose tolerance test and diabetogenic effect of streptozotocin in mice, followed by an integrative computational analysis. A total of 23 compounds were identified through GCMS and HPLC. The extract showed potent in-vitro α-amylase and α-glucosidase suppressive activity with IC50 values of 12.8 ± 0.1 µg/mL and 36.3 ± 0.07 µg/mL, respectively. In an in vivo oral glucose tolerance test, the extract (400 mg/kg body weight) prompted blood glucose levels to plummet by 18.9 % after 30 min, compared to the normal control and streptozotocin induced diabetes test, maximum glucose reduction was observed 11.67 % by dose of 200 mg/kg compared to the control; glibenclamide and extract (400 mg/kg) reduced blood glucose levels by 1.3 % and 16.7 %, respectively, compared to diabetic control at the end of the trial. Additionally, among the identified compounds, myricetin, quercetin, rutin, and kaempferol revealed good binding affinity as well as stability with the studied anti-diabetic proteins in docking and molecular dynamics simulation studies. Furthermore, QSAR analysis and network pharmacology studies of the identified compounds divulged enhanced insulin secretion stimulation, insulin receptor kinase activity, PPARγ expression; enzyme inhibition (α-glucosidase, α-amylase) and protection of the pancreas -mediated antidiabetic effects. Besides, they proved strong inhibitory potential against the studied antidiabetic proteins in other computational analysis. Based on the present findings, it can be affirmed that C. quinquefolia extract possesses anti-diabetic activity.

Licochalcone H Targets EGFR and AKT to Suppress the Growth of Oxaliplatin -Sensitive and -Resistant Colorectal Cancer Cells.

Treatment of colorectal cancer (CRC) has always been challenged by the development of resistance. We investigated the antiproliferative activity of licochalcone H (LCH), a regioisomer of licochalcone C derived from the root of Glycyrrhiza inflata, in oxaliplatin (Ox)-sensitive and -resistant CRC cells. LCH significantly inhibited cell viability and colony growth in both Ox-sensitive and Ox-resistant CRC cells. We found that LCH decreased epidermal growth factor receptor (EGFR) and AKT kinase activities and related activating signaling proteins including pEGFR and pAKT. A computational docking model indicated that LCH may interact with EGFR, AKT1, and AKT2 at the ATP-binding sites. LCH induced ROS generation and increased the expression of the ER stress markers. LCH treatment of CRC cells induced depolarization of MMP. Multi-caspase activity was induced by LCH treatment and confirmed by Z-VAD-FMK treatment. LCH increased the number of sub-G1 cells and arrested the cell cycle at the G1 phase. Taken together LCH inhibits the growth of Ox-sensitive and Ox-resistant CRC cells by targeting EGFR and AKT, and inducing ROS generation and ER stress-mediated apoptosis. Therefore, LCH could be a potential therapeutic agent for improving not only Ox-sensitive but also Ox-resistant CRC treatment.

Global transcriptome analysis reveals fungal disease responsive core gene regulatory landscape in tea

Fungal infections are the inevitable limiting factor for productivity of tea. Transcriptome reprogramming recruits multiple regulatory pathways during pathogen infection. A comprehensive meta-analysis was performed utilizing previously reported, well-replicated transcriptomic datasets from seven fungal diseases of tea. The study identified a cumulative set of 18,517 differentially expressed genes (DEGs) in tea, implicated in several functional clusters, including the MAPK signaling pathway, transcriptional regulation, and the biosynthesis of phenylpropanoids. Gene set enrichment analyses under each pathogen stress elucidated that DEGs were involved in ethylene metabolism, secondary metabolism, receptor kinase activity, and various reactive oxygen species detoxification enzyme activities. Expressional fold change of combined datasets highlighting 2258 meta-DEGs shared a common transcriptomic response upon fungal stress in tea. Pervasive duplication events caused biotic stress-responsive core DEGs to appear in multiple copies throughout the tea genome. The co-expression network of meta-DEGs in multiple modules demonstrated the coordination of appropriate pathways, most of which involved cell wall organization. The functional coordination was controlled by a number of hub genes and miRNAs, leading to pathogenic resistance or susceptibility. This first-of-its-kind meta-analysis of host–pathogen interaction generated consensus candidate loci as molecular signatures, which can be associated with future resistance breeding programs in tea.

Phase separation underlies signaling activation of oncogenic NTRK fusions

NTRK (neurotrophic tyrosine receptor kinase) gene fusions that encode chimeric proteins exhibiting constitutive activity of tropomyosin receptor kinases (TRK), are oncogenic drivers in multiple cancer types. However, the underlying mechanisms in oncogenesis that involve various N-terminal fusion partners of NTRK fusions remain elusive. Here, we show that NTRK fusion proteins form liquid-like condensates driven by their N-terminal fusion partners. The kinase reactions are accelerated in these condensates where the complexes for downstream signaling activation are also concentrated. Our work demonstrates that the phase separation driven by NTRK fusions is not only critical for TRK activation, but the condensates formed through phase separation serve as organizational hubs for oncogenic signaling.

An EGCG Derivative in Combination with Nimotuzumab for the Treatment of Wild-Type EGFR NSCLC.

Inhibiting the tyrosine kinase activity of epidermal growth factor receptor (EGFR) using small-molecule tyrosine kinase inhibitors (TKIs) or monoclonal antibodies is often ineffective in treating cancers harboring wild-type EGFR. Given the fact that EGFR possesses a kinase-independent pro-survival function, more effective inhibition of EGFR-mediated signals is therefore necessary. In this study, we investigated the effects of using a combination of low-dose nimotuzumab and theasinensin A to evaluate whether the inhibitory effect of nimotuzumab on NCI-H441 cancer cells was enhanced. Here, theasinensin A, a novel epigallocatechin-3-gallate (EGCG) derivative, was identified and its potent anticancer activity against wild-type EGFR NSCLC was demonstrated in vitro; the anticancer activity was induced through degradation of EGFR. Mechanistic studies further revealed that theasinensin A bound directly to the EGFR extracellular domain, which decreased interaction with its ligand EGF in combination with nimotuzumab. Theasinensin A significantly promoted EGFR degradation and repressed downstream survival pathways in combination with nimotuzumab. Meanwhile, treatment with theasinensin A and nimotuzumab prevented xenograft growth, whereas the single agents had limited effect. Thus, the combination therapy of theasinensin A with nimotuzumab is a powerful candidate for treatment of wild-type EGFR cancers.

LAMC2 promotes EGFR cell membrane localization and acts as a novel biomarker for tyrosine kinase inhibitors (TKIs) sensitivity in lung cancer

The epidermal growth factor receptor (EGFR) is one of the first and most prominent driver genes known to promote malignant lung cancer. Investigating regulatory mechanisms beyond ligand-receptor binding, phosphorylation, and receptor kinase activation as means of EGFR signaling activation is important for improving EGFR-targeted therapy. Here, we report that Laminin-5γ-2 (LAMC2) retained high oncogenic capacity in lung cancer, silencing LAMC2 inhibited EGFR-induced cell proliferation and tumor growth in vivo. Deletion mutation experiments showed that both the EGF-Lam and LamB regions of LAMC2 are necessary for EGFR receptor binding, and that LAMC2 and EGFR were found to co-localize at the endoplasmic reticulum (ER) membrane. In addition, LAMC2 overexpression enhanced EGFR membrane deposition and promoted EGFR transport from the ER. Moreover, LAMC2 was necessary for preventing EGFR protein degradation via ubiquitination. Lastly, our study showed that high LAMC2 expression is positively associated with response to gefitinib (EGFR tyrosine kinase inhibitor) treatment. Overall, our study revealed a new regulatory mechanism of LAMC2 in promoting EGFR protein expression and stability by facilitating ER transport and preventing protein degradation via ubiquitination. Moreover, LAMC2 may serve as a stratifying biomarker for patients suitable for EGFR-TKI treatment.

Identification of the Brucea javanica Constituent Brusatol as a EGFR-Tyrosine Kinase Inhibitor in a Cell-Free Assay.

Inhibitors of the tyrosine kinase (TK) activity of the epidermal growth factor receptor (EGFR) are routinely used in cancer therapy. However, there is a need to discover a new TK inhibitor. This study evaluated extracts from Brucea javanica and its components for their potential as novel EGFR-TK inhibitors. The cytotoxic effect of a g aqueous extract and its fractions was assessed by MTT assays with A549 lung cancer cells. The two fractions with the highest cytotoxicity were analyzed by LC/MS and 1H NMR. Brusatol was identified as the main constituent of these fractions, and its cytotoxic and pro-apoptotic activities were confirmed in A549 cells. To elucidate the inhibitory activity of brusatol against EGFR-TK, a specific ADP-GloTM kinase assay was used. In this assay, the IC50 value for EGFR-TK inhibition was 333.1 nM. Molecular dynamic simulations and docking experiments were performed to identify the binding pocket of brusatol to be located in the intracellular TK-domain of EGFR. This study demonstrates that brusatol inhibits EGFR-TK and therefore harbors a potential as a new therapeutic drug for the therapy of EGFR-depending cancers.

LDL Transcytosis by the Arterial Endothelium-Atherosclerosis by a Thousand Cuts?

The accumulation of LDL in the arterial intima is an initiating event in atherosclerosis. After decades of controversy, it is now clear that transcytosis of LDL across an intact endothelial monolayer contributes to its intimal deposition. We review recent observations in this field and address the question of whether LDL transcytosis can be manipulated therapeutically. The development of a live-cell imaging method for studying transcytosis using total internal reflection fluorescence (TIRF) microscopy has catalyzed recent discoveries. LDL transcytosis is mediated by SR-BI and ALK1. Estrogen down-regulates SR-BI and inhibits LDL transcytosis, while the nuclear structural protein HMGB1 promotes LDL transcytosis. LDL transcytosis by ALK1 is independent of the receptor's kinase activity and is antagonized by BMP9, ALK1's canonical ligand. Inflammation stimulates LDL transcytosis. Identifying the function and mechanisms of LDL transcytosis may ultimately permit its therapeutic manipulation.

Hepatic stellate cells maintain liver homeostasis through paracrine neurotrophin-3 signaling that induces hepatocyte proliferation.

Organ size is maintained by the controlled proliferation of distinct cell populations. In the mouse liver, hepatocytes in the midlobular zone that are positive for cyclin D1 (CCND1) repopulate the parenchyma at a constant rate to preserve liver mass. Here, we investigated how hepatocyte proliferation is supported by hepatic stellate cells (HSCs), pericytes that are in close proximity to hepatocytes. We used T cells to ablate nearly all HSCs in the murine liver, enabling the unbiased characterization of HSC functions. In the normal liver, complete loss of HSCs persisted for up to 10 weeks and caused a gradual reduction in liver mass and in the number of CCND1+ hepatocytes. We identified neurotrophin-3 (Ntf-3) as an HSC-produced factor that induced the proliferation of midlobular hepatocytes through the activation of tropomyosin receptor kinase B (TrkB). Treating HSC-depleted mice with Ntf-3 restored CCND1+ hepatocytes in the midlobular region and increased liver mass. These findings establish that HSCs form the mitogenic niche for midlobular hepatocytes and identify Ntf-3 as a hepatocyte growth factor.

Loss of hepatic PPARα in mice causes hypertension and cardiovascular disease.

The leading cause of death in patients with nonalcoholic fatty liver disease (NAFLD) is cardiovascular disease (CVD). However, the mechanisms are unknown. Mice deficient in hepatocyte proliferator-activated receptor-α (PPARα) (PparaHepKO) exhibit hepatic steatosis on a regular chow diet, making them prone to manifesting NAFLD. We hypothesized that the PparaHepKO mice might be predisposed to poorer cardiovascular phenotypes due to increased liver fat content. Therefore, we used PparaHepKO and littermate control mice fed a regular chow diet to avoid complications with a high-fat diet, such as insulin resistance and increased adiposity. After 30 wk on a standard diet, male PparaHepKO mice exhibited elevated hepatic fat content compared with littermates as measured by Echo MRI (11.95 ± 1.4 vs. 3.74 ± 1.4%, P < 0.05), hepatic triglycerides (1.4 ± 0.10 vs. 0.3 ± 0.01 mM, P < 0.05), and Oil Red O staining, despite body weight, fasting blood glucose, and insulin levels being the same as controls. The PparaHepKO mice also displayed elevated mean arterial blood pressure (121 ± 4 vs. 108 ± 2 mmHg, P < 0.05), impaired diastolic function, cardiac remodeling, and enhanced vascular stiffness. To determine mechanisms controlling the increase in stiffness in the aorta, we used state-of-the-art PamGene technology to measure kinase activity in this tissue. Our data suggest that the loss of hepatic PPARα induces alterations in the aortas that reduce the kinase activity of tropomyosin receptor kinases and p70S6K kinase, which might contribute to the pathogenesis of NAFLD-induced CVD. These data indicate that hepatic PPARα protects the cardiovascular system through some as-of-yet undefined mechanism.

Unexpected Need of the Epidermal Growth Factor Receptor Tyrosine Kinase Activity for Signaling by Intracellular Pattern Recognition Receptors of Nucleic Acids.

Many pattern recognition receptors in mammalian cells initiate signaling processes that culminate in mounting an innate protective response mediated by induced synthesis of a large number of proteins including type I interferons and other cytokines. Many of these receptors are not located on the plasma membrane but on the membranes of intracellular organelles such as endosomes, mitochondria, and the endoplasmic reticulum; they primarily recognize microbial or cellular nucleic acids. In the course of biochemical analyses of the signaling pathways triggered by these receptors, we discovered that they require tyrosine phosphorylation by the protein kinase activity of the epidermal growth factor receptor (EGFR), which is located not only on the plasma membrane but also on the intracellular membranes. Here, we discuss how specific members of this family of receptors, such as TLR3, TLR9, or STING, interact with EGFR and other protein tyrosine kinases and what are the functional consequences of their post-translational modifications. The article highlights an unexpected functional link between a growth factor receptor and cellular innate immune response.

Abstract CT228: Concordance between tissue and circulating tumor DNA (ctDNA) testing for neurotrophic tyrosine receptor kinase (NTRK) gene fusions in larotrectinib (laro) clinical trials

Abstract Background: NTRK gene fusions are oncogenic drivers in various tumor types. Laro, a highly selective and central nervous system (CNS)-active tropomyosin receptor kinase (TRK) inhibitor, is approved for the treatment of patients (pts) with TRK fusion cancer. Laro demonstrated an objective response rate (ORR) of 69% in 244 pts with solid (non-primary CNS) tumors (Drilon et al. ASCO 2022). Here, we report on the concordance between baseline local tissue-based testing with central tissue-based and liquid biopsy-based ctDNA testing to identify NTRK gene fusions. Methods: Pts with non-primary CNS TRK fusion cancer who underwent independent review committee assessments by July 15, 2019, in three laro clinical trials (NCT02122913, NCT02576431, and NCT02637687) were included. Tumor NTRK gene fusion status was determined locally by a variety of methods, and centrally by next-generation sequencing in both tissue (using Illumina TruSight™ Oncology Comprehensive) and ctDNA (using Guardant360® or GuardantOMNI®) at baseline. Data cut-off: July 20, 2021. Results: Of the 164 pts with NTRK fusions identified by local testing, 117 had evaluable tissue samples for central testing, and 99 had evaluable liquid biopsy samples. In total, 81.2% (95/117) of tumors had the fusion confirmed by central tissue testing. ctDNA testing detected NTRK gene fusions in 33.3% (33/99) of patients. Positive predictive values for each NTRK gene fusion are shown in the Table. The ORR for pts with NTRK gene fusions determined by local and central testing will be presented. Conclusions: A high proportion of tumors with locally identified NTRK gene fusions were confirmed centrally. At present, analysis of ctDNA is significantly less sensitive at detecting NTRK gene fusions. A negative ctDNA result requires next-generation sequencing testing of a tissue biopsy. Further research is needed to improve the sensitivity of ctDNA gene fusion detection. Table NTRK gene fusion Tissue-based LT Tissue-based CT ctDNA-based CT with LB Fusion confirmed, n Fusion confirmed, n Fusion not detected, n Unavailable samples, n† PPV‡: CT vs tissue-based LT, % Fusion confirmed, n Fusion not detected, n Unavailable samples, n† PPV‡: LB vs tissue-based LT, % NTRK1 68 35 14 19 71.4 20 34 14 37.0 NTRK2 4 3 1 0 75.0 0 4 0 0 NTRK3 92§ 57 7 28 89.1 13 28 51 31.7 †Includes no sample available and sample QC failed. ‡Calculated as a percentage of the number of confirmed fusions over the number of available samples. §Includes 9 inferred NTRK3 fusions. CT, central testing; ctDNA, circulating tumor DNA; LB, liquid biopsy; LT, local testing; NTRK, neurotrophic tyrosine receptor kinase; PPV, positive predictive value; QC, quality control. Citation Format: Erin R. Rudzinski, Marc Ladanyi, Lauren L. Ritterhouse, Felix Sahm, Ricarda Norenberg, Hong Zheng, Chi Chen, Vadim Bernard-Gauthier, Nicoletta Brega, Cornelis M. van Tilburg, Jessica J. Lin, Marcia S. Brose, Ulrik N. Lassen, Ray McDermott, Theodore W. Laetsch, David S. Hong, Alexander Drilon, Sinchita Roy-Chowdhuri. Concordance between tissue and circulating tumor DNA (ctDNA) testing for neurotrophic tyrosine receptor kinase (NTRK) gene fusions in larotrectinib (laro) clinical trials [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT228.

S-acylation stabilizes ligand-induced receptor kinase complex formation during plant pattern-triggered immune signaling

Plant receptor kinases are key transducers of extracellular stimuli, such as the presence of beneficial or pathogenic microbes or secreted signaling molecules. Receptor kinases are regulated by numerous post-translational modifications.1,2,3 Here, using the immune receptor kinases FLS24 and EFR,5 we show that S-acylation at a cysteine conserved in all plant receptor kinases is crucial for function. S-acylation involves the addition of long-chain fatty acids to cysteine residues within proteins, altering their biochemical properties and behavior within the membrane environment.6 We observe S-acylation of FLS2 at C-terminal kinase domain cysteine residues within minutes following the perception of its ligand, flg22, in a BAK1 co-receptor and PUB12/13 ubiquitin ligase-dependent manner. We demonstrate that S-acylation is essential for FLS2-mediated immune signaling and resistance to bacterial infection. Similarly, mutating the corresponding conserved cysteine residue in EFR suppressed elf18-triggered signaling. Analysis of unstimulated and activated FLS2-containing complexes using microscopy, detergents, and native membrane DIBMA nanodiscs indicates that S-acylation stabilizes, and promotes retention of, activated receptor kinase complexes at the plasma membrane to increase signaling efficiency.

Use of Apatinib as a Bait to Fish its Unexpected Kinase Targets from the Hepatocellular Carcinoma Druggable Kinome

Apatinib is a tyrosine kinase inhibitor that cognately blocks the kinase activity of vascular endothelial growth factor receptor (VEGFR) signaling for the treatment of advanced gastric cancer (GC). However, the drug is also clinically found to reposition a significant suppressing potency on hepatocellular carcinoma (HCC). In this study, we reported the successful use of Apatinib as a bait to fish its potential kinase targets from the HCC druggable kinome pool. In the procedure, cell viability assays observed that the Apatinib has a potent cytotoxicity on human HCC cell lines. Dynamics simulations and affinity scoring systematically created an intermolecular interaction profile of Apatinib with ontologically enriched kinases in the HCC druggable kinome, from which the top-hit kinases were considered as potential candidates. It is revealed that the inhibitor has a weak potency on the well-established HCC target of ErbB pathway, but exhibits potent activity against some known targets or regulators of HCC. In particular, kinase assays substantiated that Apatinib can effectively inhibit four FGFR family members with moderate or high activity. In addition, the clinical FGFR1 gatekeeper mutation V561M was also observed to considerably impair the inhibitory activity, thus causing a drug resistance. Molecular modeling suggested that the Apatinib adopts two distinct binding modes to separately interact with wild-type and gatekeeper-mutant FGFR1 kinase domain.

Effect of Janus kinase (JAK) signaling inhibition on lineage plasticity and drug sensitivity in castrate resistant prostate cancer.

227 Background: Despite the remarkable successes of targeted cancer therapies, certain cancers, including lung, breast, and prostate cancer and melanoma, invariably become resistant to therapy. One mechanism of secondary resistance—lineage plasticity—arises when cells alter their identity and transition into aggressive states. In the case of prostate cancer, cells can acquire a neuroendocrine histology. This is often associated with a loss of tumor suppressor genes, such as TP53, RB1, and PTEN. However, while these genomic events initiate plasticity, tumor progression is not always associated with successive genomic alterations. This, in essence, not only poses a clinical challenge, but also confronts us with a wide-open biological question—what are the molecular underpinnings of lineage plasticity, and importantly, can the process be reversed? Methods: To study the temporal evolution of lineage plasticity and its relationship to androgen receptor signaling inhibitor (ARSI) resistance, we utilized genetically engineered mouse models (GEMMs) and murine organoids that were deleted for Tp53, Rb1, and/or Pten. Single cell RNA analyses were utilized to dissect which genes and pathways were up-regulated and most associated with the progression of plasticity. Plasticity-associated genes and pathways were perturbed using FDA-approved inhibitors or genetic editing tools. The presence of these pathways was confirmed in a subset of metastatic index lesions obtained by radiologically guided biopsies and as visualized by metabolic imaging. Furthermore, relevant findings were functionally validated in human tumor derived organoids (“tumoroids”). Results: Using GEMMs and organoid models, we found the lineage plasticity depended on increased Janus Kinase (JAK) and fibroblast growth factor receptor (FGFR) activity. Pharmacologic inhibition using FDA–approved inhibitors of JAK/STAT (ruxolitinib) and FGFR (erdafinitib), or through genetic knockdown, demonstrated increased androgen receptor (AR) signaling and restored ARSI sensitivity. These findings were further validated in a subset of ARSI-insensitive human tumoroids. By performing single cell RNA sequencing on mCRPC tumors biopsies, the presence of highly plastic JAK/STAT- and FGFR-high cells were confirmed, with implications for stratifying patients for clinical trials. Conclusions: JAK/STAT and FGFR signaling pathways promote lineage plasticity and result in complete insensitivity to androgen receptor signaling inhibitors (ARSIs). FDA-approved inhibitors of JAK/STAT (ruxolitinib) and FGFR (erdafitinib) synergize to reverse lineage plasticity and restore ARSI sensitivity.

Pancreastatin inhibitor PSTi8 ameliorates streptozotocin-induced diabetes by suppressing hepatic glucose production

Elevated plasma glucose concentration, as a consequence of excessive hepatic glucose production, plays a pivotal role in the development of diabetes. A chromogranin A-derived diabetogenic peptide Pancreastatin (PST) enhances hepatic glucose output leading to diabetes. Therefore, here we probed the role of PSTi8, a PST inhibitor in ameliorating diabetes by investigating the effect of high glucose (HG) or PST on glucose metabolism. Further, we also explored the action mechanism of the underlying anti-hyperglycemic effect of PSTi8. PSTi8 treatment rescue cultured L6 and HepG2 cells from HG and PST-induced insulin resistance, respectively. It also enhances insulin receptor kinase activity by interacting with the insulin receptor and enhancing GLUT4 translocation and glucose uptake. Thus, our in-silico and in-vitro data support the PST-dependent and independent activity of PSTi8. Additionally, PSTi8 treatment in streptozotocin-induced diabetic rats improved glucose tolerance by lowering blood glucose and plasma PST levels. Concomitantly, the treated animals exhibited reduced hepatic glucose production accompanied by downregulation of hepatic gluconeogenic genes PEPCK and G6Pase. PSTi8-treated rats also exhibited enhanced hepatic glycogen in line with reduced plasma glucagon concentrations. Consistently, improved plasma insulin levels in PSTi8-treated rats enhanced skeletal muscle glucose disposal via enhanced P-Akt expression. In summary, these findings suggest PSTi8 has anti-hyperglycemic properties with enhanced skeletal muscle glucose disposal and reduced hepatic gluconeogenesis both PST dependent as well as independent.

Antitumour activity of neratinib in patients with HER2-mutant advanced biliary tract cancers

HER2 mutations are infrequent genomic events in biliary tract cancers (BTCs). Neratinib, an irreversible, pan-HER, oral tyrosine kinase inhibitor, interferes with constitutive receptor kinase activation and has activity in HER2-mutant tumours. SUMMIT is an open-label, single-arm, multi-cohort, phase 2, ‘basket’ trial of neratinib in patients with solid tumours harbouring oncogenic HER2 somatic mutations (ClinicalTrials.gov: NCT01953926). The primary objective of the BTC cohort, which is now complete, is first objective response rate (ORR) to neratinib 240 mg orally daily. Secondary objectives include confirmed ORR, clinical benefit rate, progression-free survival, duration of response, overall survival, safety and tolerability. Genomic analyses were exploratory. Among 25 treatment-refractory patients (11 cholangiocarcinoma, 10 gallbladder, 4 ampullary cancers), the ORR is 16% (95% CI 4.5–36.1%). The most common HER2 mutations are S310F (n = 11; 48%) and V777L (n = 4; 17%). Outcomes appear worse for ampullary tumours or those with co-occurring oncogenic TP53 and CDKN2A alterations. Loss of amplified HER2 S310F and acquisition of multiple previously undetected oncogenic co-mutations are identified at progression in one responder. Diarrhoea is the most common adverse event, with any-grade diarrhoea in 14 patients (56%). Although neratinib demonstrates antitumour activity in patients with refractory BTC harbouring HER2 mutations, the primary endpoint was not met and combinations may be explored.

Divergent Roles of Ephrin-B2/EphB4 Guidance System in Pulmonary Hypertension.

Smooth muscle cell (SMC) expansion is one key morphological hallmark of pathologically altered vasculature and a characteristic feature of pulmonary vascular remodeling in pulmonary hypertension. Normal embryonal vessel maturation requires successful coverage of endothelial tubes with SMC, which is dependent on ephrin-B2 and EphB4 ligand-receptor guidance system. In this study, we investigated the potential role of ephrin-B2 and EphB4 on neomuscularization in adult pulmonary vascular disease. Ephrin-B2 and EphB4 expression is preserved in smooth muscle and endothelial cells of remodeled pulmonary arteries. Chronic hypoxia-induced pulmonary hypertension was not ameliorated in mice with SMC-specific conditional ephrin-B2 knockout. In mice with global inducible ephrin-B2 knockout, pulmonary vascular remodeling and right ventricular hypertrophy upon chronic hypoxia exposure were significantly diminished compared to hypoxic controls, while right ventricular systolic pressure was unaffected. In contrast, EphB4 receptor kinase activity inhibition reduced right ventricular systolic pressure in hypoxia-induced pulmonary hypertension without affecting pulmonary vascular remodeling. Genetic deletion of ephrin-B2 in murine pulmonary artery SMC, and pharmacological inhibition of EphB4 in human pulmonary artery smooth muscle cells, blunted mitogen-induced cell proliferation. Loss of EphB4 signaling additionally reduced RhoA expression and weakened the interaction between human pulmonary artery smooth muscle cells and endothelial cells in a three-dimensional coculture model. In sum, pulmonary vascular remodeling was dependent on ephrin-B2-induced Eph receptor (erythropoietin-producing hepatocellular carcinoma receptor) forward signaling in SMC, while EphB4 receptor activity was necessary for RhoA expression in SMC, interaction with endothelial cells and vasoconstrictive components of pulmonary hypertension.

Retinoic acid-gated BDNF synthesis in neuronal dendrites drives presynaptic homeostatic plasticity.

Homeostatic synaptic plasticity is a non-Hebbian synaptic mechanism that adjusts synaptic strength to maintain network stability while achieving optimal information processing. Among the molecular mediators shown to regulate this form of plasticity, synaptic signaling through retinoic acid (RA) and its receptor, RARα, has been shown to be critically involved in the homeostatic adjustment of synaptic transmission in both hippocampus and sensory cortices. In this study, we explore the molecular mechanism through which postsynaptic RA and RARα regulates presynaptic neurotransmitter release during prolonged synaptic inactivity at mouse glutamatertic synapses. We show that RARα binds to a subset of dendritically sorted brain-derived neurotrophic factor (Bdnf) mRNA splice isoforms and represses their translation. The RA-mediated translational de-repression of postsynaptic BDNF results in the retrograde activation of presynaptic tropomyosin receptor kinase B (TrkB) receptors, facilitating presynaptic homeostatic compensation through enhanced presynaptic release. Together, our study illustrates an RA-mediated retrograde synaptic signaling pathway through which postsynaptic protein synthesis during synaptic inactivity drives compensatory changes at the presynaptic site.