MAPK Activation Research Articles

CD24 regulates liver immune response and ameliorates acute hepatic injury through controlling hepatic macrophages.

Liver injury releases danger-associated molecular patterns, which trigger the immune response. CD24 negatively regulates the immune response by binding with danger-associated molecular patterns, but the specific role of CD24 in modulating macrophage-related inflammation during liver injury remains largely unexplored. Here, we aimed to investigate the mechanisms of macrophage CD24 in the development of liver injury. Our results show that CD24 expression is upregulated primarily in hepatic macrophages (HMs) during acute liver injury. CD24-deficient mice exhibited more severe liver injury and showed a significantly higher frequency and number of HMs, particularly Ly6Chi monocyte-derived macrophages. Mechanistically, the CD24-Siglec-G interaction plays a vital role in mitigating acute liver injury. CD24-mediated inhibitory signaling in HMs primarily limits downstream NF-κB and p38 MAPK activation through the recruitment of SHP1. Our work unveils the critical role of macrophage CD24 in negatively regulating innate immune responses and protecting against acute liver injury, thus providing potential therapeutic targets for liver-associated diseases.

Ketamine and Major Ketamine Metabolites Function as Allosteric Modulators of Opioid Receptors.

Ketamine is a glutamate receptor antagonist that was developed over 50 years ago as an anesthetic agent. At subanesthetic doses, ketamine and some metabolites are analgesics and fast-acting antidepressants, presumably through targets other than glutamate receptors. We tested ketamine and its metabolites for activity as allosteric modulators of opioid receptors expressed as recombinant receptors in heterologous systems and with native receptors in rodent brain; signaling was examined by measuring GTP binding, β-arrestin recruitment, MAPK activation, and neurotransmitter release. Although micromolar concentrations of ketamine alone had weak agonist activity at μ opioid receptors, the combination of submicromolar concentrations of ketamine with endogenous opioid peptides produced robust synergistic responses with statistically significant increases in efficacies. All three opioid receptors (μ, δ, and κ) showed synergism with submicromolar concentrations of ketamine and either methionine-enkephalin (Met-enk), leucine-enkephalin (Leu-enk), and/or dynorphin A17 (Dyn A17), albeit the extent of synergy was variable between receptors and peptides. S-ketamine exhibited higher modulatory effects compared with R-ketamine or racemic ketamine, with ∼100% increase in efficacy. Importantly, the ketamine metabolite 6-hydroxynorketamine showed robust allosteric modulatory activity at μ opioid receptors; this metabolite is known to have analgesic and antidepressant activity but does not bind to glutamate receptors. Ketamine enhanced potency and efficacy of Met-enkephalin signaling both in mouse midbrain membranes and in rat ventral tegmental area neurons as determined by electrophysiology recordings in brain slices. Taken together, these findings support the hypothesis that some of the therapeutic effects of ketamine and its metabolites are mediated by directly engaging the endogenous opioid system. SIGNIFICANCE STATEMENT: This study found that ketamine and its major biologically active metabolites function as potent allosteric modulators of μ, δ, and κ opioid receptors, with submicromolar concentrations of these compounds synergizing with endogenous opioid peptides, such as enkephalin and dynorphin. This allosteric activity may contribute to ketamine's therapeutic effectiveness for treating acute and chronic pain and as a fast-acting antidepressant drug.

7948 Integration Of Epigenomics And Metabolomics Reveals New Signaling In Aggressive Thyroid Cancer

Abstract Disclosure: A. Sanghi: None. S. Wu: None. T. Chou: None. L.A. Orloff: None. M. Kasowski: None. M. Snyder: None. Although genetic mutations are causal in human cancers, the contribution of chromatin changes to cancer onset and progression remains less well understood. Multi-omics profiling of human tumors can provide insight into how alterations in chromatin structure are propagated through the pathway of gene expression to result in cancer signaling. We applied multi-omics profiling of 36 human thyroid cancer primary tumors, metastases, and patient-matched normal tissue. Over 80% of the tumors harbored BRAFV600E mutations, and the remaining tumors mostly had activating mutations in the MAPK pathway. Through quantification of chromatin accessibility associated with active transcription units and global protein expression, we identify local enhancers that are highly correlated with coordinated RNA and protein expression. The enhancers are predicted to be actively bound by MAPK transcription factor, indicating they are under MAPK control. These cancer-specific enhancers associated with upregulation of lysosomal peptidase expression and dipeptide abundance in tumors. We show that upregulated dipeptides stimulate MAPK activity, and BRAF inhibition results in loss of lysosomal function in mutants. Perturbation of lysosomal peptidases and dipeptide abundance decreases MAPK activity only in mutant cells compared to wildtype. These analyses suggest that BRAF thyroid tumors integrate MAPK-driven epigenetic regulation with lysosomal metabolite signaling in a positive feedback circuit. Using local cancer-specific epigenetic features, we isolated key cancer signaling, making way for potential targets for cancer therapeutics. Presentation: 6/3/2024

Characterizing the genomic landscape through the lens of FOLR1 status in low and high grade serous ovarian carcinoma

ObjectiveTargeted therapy in folate receptor alpha (FOLR1)-positive high grade serous ovarian carcinoma (HGSOC) is now a mainstay for platinum-resistant disease. However, the rate of FOLR1-positivity in low grade serous ovarian carcinoma (LGSOC) is not well documented. Less common than HGSOC, LGSOC tends to respond poorly to traditional platinum-based chemotherapeutic regimens, particularly in recurrence. Thus, there is an urgent need to identify molecular targets that may assist in identifying more efficacious treatments for LGSOC. In this work, we assessed the genomic and transcriptomic landscapes in FOLR1-positive/negative LGSOC compared to its high-grade counterpart. MethodsUsing a large precision oncology database, next-generation sequencing and immunohistochemistry was performed on a cohort of 281 LGSOC and 5086 HGSOC. Associated MAPK activation was calculated based on NGS results and patient survival analysis was completed stratified by molecular alteration. ResultsCompared with LGSOC (24.6 %), HGSOC tumors have significantly higher prevalence of FOLR1+ status (43.5 %) and significantly higher PD-L1+ status. Conversely, LGSOC had higher prevalence of KRAS and NRAS mutations, with a near exclusivity for BRAF mutation compared to HGSOC. FOLR1- LGSOC and HGSOC had similar prevalences of T cell-inflamed tumors, though FOLR1+ LGSOC had a significantly lower prevalence of T-Cell inflamed tumors than FOLR1+ HGSOC. MAPK activation, quantified via MAPK activation score (MPAS), was significantly higher in low-grade tumors compared to HGSOC, yet no difference between FOLR1+ vs FOLR1- LGSOC was observed. ConclusionsThough less than in high-grade disease, a notable portion of low-grade tumors were FOLR1+, suggesting FOLR1 expression in LGSOC could be a viable target for this rare histology, particularly in the recurrent setting.

Calcium-Dependent Protein Kinase 5 and 13 enhance salt tolerance in rice by directly activating OsMPK3/6 kinases.

Mitogen-activated protein kinases (MAPKs/MPKs) are pivotal regulators in many stress-signaling pathways in plants. The dual phosphorylation of the TXY motif by MAP Kinase Kinases (MKKs) is essential for activating MAPKs. Here, we reveal a mechanism for MAPK activation that bypasses the need for MKKs. We identified rice (Oryza sativa) calcium-dependent protein kinase 5 (OsCPK5) and OsCPK13as positive regulators in salt stress tolerance. These kinases are essential for the full activation of OsMPK3 and OsMPK6 in response to elevated sodium levels, with both OsMPK3 and OsMPK6 also acting as positive regulators in rice salt tolerance. Biochemical analysis demonstrated that OsCPK5/13 directly interact with and activate OsMPK3/6 by phosphorylating the TXY motif in vitro and in vivo. Additionally, we have discovered that OsCPK5/13 relocate from the cell membrane to the nucleus in response to salt stress. This process relies on their N-terminal myristoylation and a calcium-dependent phosphorylation event within the N-terminus. Our results elucidate a MAPK activation pathway in rice that is independent of traditional MKK-mediated phosphorylation, highlighting the crucial roles of OsCPK5 and OsCPK13 in directly phosphorylating and activating OsMPK3/6, which are important for rice tolerance to salt stress.

DNA damage-inducible transcript 3 positively regulates RIPK1-mediated necroptosis.

DNA damage-inducible transcript 3 (DDIT3) is a well-known transcription factor that regulates the expression of apoptosis-related genes for promoting apoptosis during endoplasmic reticulum stress. Here, we report an unrecognized role of DDIT3 in facilitating necroptosis. DDIT3 directly binds and competitively prevents the p38 MAPK-MK2 interaction and thereby blocking MK2 activation while stimulating p38 MAPK activation. This blockage of MK2 activation initially prevents RIPK1 phosphorylation at Ser320 (inactivation), subsequently relieving its suppression of RIPK1 activation. Consequently, p38 MAPK facilitates RIPK1 phosphorylation at Ser166 (activation) through DDIT3 phosphorylation-related mechanisms, leading to necroptosis. Mechanistically, a 10-amino acid segment (Glu19-Val28) within DDIT3's N-terminus is identified to account for its pro-necroptotic function. In vivo studies demonstrate that forced expression of DDIT3 induces necroptosis, whereas deletion of DDIT3 alleviates necroptosis in mouse hearts under stress. These findings shed light on a novel regulatory mechanism by which DDIT3 promotes RIPK1 activation and subsequent necroptosis.

Complement system component 3 deficiency modulates the phenotypic profile of murine macrophages

The Complement System is composed of more than 40 proteins that act in innate and adaptive immunity. C3 is the most abundant one and C3-deficient patients are more susceptible to recurrent and severe infections. Several studies have demonstrated the importance of C3 in controlling infections. However, its role in leukocyte biology is still poorly understood. This study aimed to evaluate several cellular parameters in macrophages from C3-deficient mice and compare them to similar cells from wild-type counterparts. We observed that in the absence of C3, the population of F4/80low macrophages in the peritoneal cavity of thioglycolate-treated mice is diminished, probably due to the lack of chemotactic factors like C3a and low levels of C5a. Using fluorescence microscopy analysis, we observed that macrophages from C3-deficient mice exhibited morphological alterations when compared to similar cells from wild-type mice. We observed a significant increase in the expression of CD11c, which is part of CR4 (CD11c/CD18), in macrophages from C3-deficient compared to cells from wild-type mice. Treatment with 12-o-tetradecanoylphorbol-13-acetate, stimulated ROS production and MAPK activation by macrophages. However, these parameters were lower in macrophages from C3-deficient mice when compared to wild-type counterparts. In addition, the phagocytosis of iC3b-opsonized Zymosan particles was diminished in macrophages from C3-deficient mice. Our results suggest that C3 deficiency in C57Black/6 mice may influence specific morphological and functional parameters of macrophages, cells of fundamental importance for both the innate and acquired immune responses.

Exogenous Angiotensin-(1-7) Provides Protection Against Inflammatory Bone Resorption and Osteoclastogenesis by Inhibition of TNF-α Expression in Macrophages.

Renin-angiotensin-aldosterone system plays a crucial role in the regulation of blood pressure and fluid homeostasis. It is reported to be involved in mediating osteoclastogenesis and bone loss in diseases of inflammatory bone resorption such as osteoporosis. Angiotensin-(1-7), a product of Angiotensin I and II (Ang I, II), is cleaved by Angiotensin-converting enzyme 2 and then binds to Mas receptor to counteract inflammatory effects produced by Ang II. However, the mechanism by which Ang-(1-7) reduces bone resorption remains unclear. Therefore, we aim to elucidate the effects of Ang-(1-7) on lipopolysaccharide (LPS)-induced osteoclastogenesis. In vivo, mice were supracalvarial injected with Ang-(1-7) or LPS ± Ang-(1-7) subcutaneously. Bone resorption and osteoclast formation were compared using micro-computed tomography, tartrate-resistant acid phosphatase (TRAP) stain, and real-time PCR. We found that Ang-(1-7) attenuated tumor necrosis factor (TNF)-α, TRAP, and Cathepsin K expression from calvaria and decreased osteoclast number along with bone resorption at the suture mesenchyme. In vitro, RANKL/TNF-α ± Ang-(1-7) was added to cultures of bone marrow-derived macrophages (BMMs) and osteoclast formation was measured via TRAP staining. The effect of Ang-(1-7) on LPS-induced osteoblasts RANKL expression and peritoneal macrophages TNF-α expression was also investigated. The effect of Ang-(1-7) on the MAPK and NF-κB pathway was studied by Western blotting. As a result, Ang-(1-7) reduced LPS-stimulated macrophages TNF-α expression and inhibited the MAPK and NF-κB pathway activation. However, Ang-(1-7) did not affect osteoclastogenesis induced by RANKL/TNF-α nor reduce osteoblasts RANKL expression in vitro. In conclusion, Ang-(1-7) alleviated LPS-induced osteoclastogenesis and bone resorption in vivo via inhibiting TNF-α expression in macrophages.

Kjellmaniella crassifolia Reduces Lipopolysaccharide-Induced Inflammation in Caco-2 Cells and Ameliorates Loperamide-Induced Constipation in Mice.

Gastrointestinal disorders are widespread globally, with inflammatory diseases being particularly prominent. This study aimed to investigate the effect of Kjellmaniella crassifolia hot water extract (KCH) on lipopolysaccharide (LPS)-induced inflammation in human intestinal epithelial (Caco-2) cells and loperamide-induced constipation in BALB/c mice. The study's findings revealed that KCH dose-dependently increased the cell viability and reduced the NO production by decreasing the iNOS and COX-2 expression in LPS-stimulated Caco-2 cells. Also, KCH downregulated the mRNA expression of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) by regulating the activation of MAPK and NF-κB signaling pathways in LPS-stimulated Caco-2 cells. In addition, KCH increased the expression levels of tight junction proteins, occludin, ZO-1, and claudin-1 in a dose-dependent manner. Furthermore, in vivo study outcomes demonstrated that KCH improved intestinal transit, increased fecal moisture content, and reduced fecal impaction in constipated mice. KCH decreased the mRNA expression of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α), thereby increasing the expression levels of intestinal tight junction proteins (occludin, ZO-1, and claudin-1) in the small intestine tissues of the experimental mice. These proteins may help regulate intestinal motility and improve stool passage, thus reducing constipation. These findings suggest that KCH could be a promising functional food ingredient for managing intestinal inflammation, inflammation-related disorders, constipation, and the pathophysiology of constipation.

Analysis of the relationship between resistin with prognosis, cell migration, and p38 and ERK1/2 activation in breast cancer

Obesity increases the risk and mortality of breast cancer through dysregulated secretion of proinflammatory cytokines and tumor adipokines that induce an inflammatory breast microenvironment. Resistin is an adipokine secreted by adipocytes, immune cells, and predominantly macrophages, which contributes to cancer progression, but its molecular mechanism in cancer is not completely described. In this study, we analyzed the relationship of resistin on breast cancer prognosis and tumor progression and the effect in vitro of resistin on p38 and ERK1/2 activation in breast cancer cell lines. By bioinformatic analysis, we found that resistin is overexpressed in the basal subtype triple-negative breast cancer and is related to poor prognosis. In addition, we demonstrated a positive correlation between RETN and MAPK3 expression in basal triple-negative breast cancer. Importantly, we found amplifications of the RETN gene in at least 20 % of metastatic samples from patients with breast cancer. Most samples with RETN amplifications metastasized to bone and showed high expression of IL-8 (CXCL8) and IL-6 (IL6). Finally, resistin could be considered a prognostic marker for basal triple-negative breast cancer, and we also proposed the possibility that resistin-induced cell migration involves the activation of MAPK in breast cancer cells.

Ursodeoxycholic acid alleviates fat embolism syndrome-induced acute lung injury by inhibiting the p38 MAPK/NF-κB signalling pathway through FXR

Acute lung injury (ALI) caused by fat embolism syndrome (FES) is a disease with high mortality. This study aimed to explore the roles of ursodeoxycholic acid (UDCA) in FES-induced ALI and its underlying mechanisms. An ALI mouse model was established by allografting mouse perinephric fat. For in vitro experiments, human pulmonary microvascular endothelial cells (HPMEC) were treated with FFAs. The effects of UDCA on the expression of farnesoid X receptor (FXR) and the inflammatory response in endothelial cells were investigated. UDCA significantly inhibited the inflammatory response and the expression of proinflammatory markers during FES-induced ALI. UDCA markedly decreased TNF-α and IL-1β expression in vitro. UDCA administration markedly upregulated FXR expression and significantly reduced the phosphorylation of p38 MAPK and NF-κB p65. Knock down FXR expression decreased the effect of UDCA in vivo. Furthermore, knock down FXR expression and overexpressing FXR increased and decreased the inflammatory response, respectively, in vitro. Moreover, administration of a p38 MAPK activator reversed the anti-inflammatory effect of FXR overexpression. UDCA ameliorated inflammation during FES-induced ALI by suppressing p38 MAPK/NF-κB signalling and activating FXR. These findings provide new evidence for the potential of UDCA for FES-induced ALI treatment.

Taurochenodeoxycholic acid ameliorates the Staphylococcus aureus infection-induced acute lung injury through toll-like receptor 2 in mice

Acute lung injury (ALI) is a significant clinical problem associated with high morbidity and mortality. Inflammation induced by gram-positive bacterial pathogens, specifically Staphylococcus aureus (S. aureus), plays a major role in ALI development and other infectious diseases. Taurochenodeoxycholic acid (TCDCA) exhibits diverse biological activities and pharmacological effects. Nevertheless, the potential preventive and therapeutic effects of TCDCA and the underlying mechanism in the ALI induced by S. aureus infection remain poorly understood. Our results showed that the TCDCA (0.1 μg/g) had a beneficial effect on lung damage in mice infected with S. aureus. Specifically, TCDCA could lead to a reduction in pulmonary focal or diffuse oedema and a decrease in the infiltration of neutrophils in the S. aureus-infected lungs. We observed that TCDCA could significantly down-regulate the expression of HMGB1 in lung from S. aureus-infected mice. Furthermore, TCDCA could attenuate the production of inflammatory mediators in lungs and serum from S. aureus-infected mice. This finding further supported the notion that TCDCA potentially protects against tissue injury. In addition, TCDCA regulated the secretion of the proinflammatory cytokine, the activation of MAPK and NF-κB signaling pathways, and the activation of TLR2 in macrophages. Notably, TCDCA might reduce the secretion levels of inflammatory mediators and lung damage through the TLR2 in S. aureus-infected macrophages or mice. Altogether, TCDCA shows promise as a potential drug for preventing and treating ALI by modulating or inhibiting inflammatory mediators through TLR2.

Novel Molecular Mechanisms Underlying the Ameliorative Effect of Platelet-Rich Plasma against Electron Radiation-Induced Premature Ovarian Failure.

Radiotherapy is one of the risk factors for radiation-induced premature ovarian failure and infertility in cancer patients. The development of methods for ovarian radioprotection remains relevant. Moreover, electrons are a little-studied and promising method of radiation with the least toxic effect on normal tissues. The assessment of intracellular mechanisms regulating the protective effects of leukocyte-poor platelet-rich plasma in a model of radiation-induced premature ovarian failure caused by electron irradiation. Wistar rats were divided into four groups, namely a control group, irradiation group (electron exposure), irradiation + leukocyte-poor platelet-rich plasma group, and only leukocyte-poor platelet-rich plasma group. Fragments of ovaries were removed and hormonal, oxidant, histological, and morphometric studies were carried out. The cell cycle of ovarian follicles and the inflammatory and vascular response were assessed using immunohistochemistry. The activity of MAPK, ERK, and PI3K pathways was also assessed using the RT-qPCR. We found that electron irradiation causes a decrease in the functional activity of the ovaries and the death of follicular cells through apoptosis. The administration of LP-PRP led to a partial restoration of the cytokine balance. In addition, minor ovarian damage and mild inflammation were observed in this group. Leukocyte-poor platelet-rich plasma components have anti-inflammatory, angiogenetic, and radioprotective effects, reducing the activation of the NOX4, caspase and cytokine cascades, and inflammatory response severity through the MAPK/p38/JNK signaling pathway. This leads to the induction of endogenous antioxidant protection, the repair of post-radiation follicular damage, and slowing down the development of radiation-induced premature ovarian failure after electron irradiation.

Cytomegalovirus results in poor graft function via bone marrow-derived endothelial progenitor cells.

Poor graft function (PGF), characterized by myelosuppression, represents a significant challenge following allogeneic hematopoietic stem cell transplantation (allo-HSCT) with human cytomegalovirus (HCMV) being established as a risk factor for PGF. However, the underlying mechanism remains unclear. Bone marrow endothelial progenitor cells (BM-EPCs) play an important role in supporting hematopoiesis and their dysfunction contributes to PGF development. We aim to explore the effects of CMV on BM-EPCs and its underlying mechanism. We investigated the compromised functionality of EPCs derived from individuals diagnosed with HCMV viremia accompanied by PGF, as well as after infected by HCMV AD 169 strain in vitro, characterized by decreased cell proliferation, tube formation, migration and hematopoietic support, and increased apoptosis and secretion of TGF-β1. We demonstrated that HCMV-induced TGF-β1 secretion by BM-EPCs played a dominant role in hematopoiesis suppression in vitro experiment. Moreover, HCMV down-regulates Vitamin D receptor (VDR) and subsequently activates p38 MAPK pathway to promote TGF-β1 secretion by BM-EPCs. HCMV could infect BM-EPCs and lead to their dysfunction. The secretion of TGF-β1 by BM-EPCs is enhanced by CMV through the activation of p38 MAPK via a VDR-dependent mechanism, ultimately leading to compromised support for hematopoietic progenitors by BM EPCs, which May significantly contribute to the pathogenesis of PGF following allo-HSCT and provide innovative therapeutic strategies targeting PGF.

NADPH oxidase 1/4 dual inhibitor setanaxib suppresses platelet activation and thrombus formation

AimsThe production of reactive oxygen species (ROS) by NADPH oxidase (NOX) is able to induce platelet activation, making NOX a promising target for antiplatelet therapy. In this study, we examined the effects of setanaxib, a dual NOX1/4 inhibitor, on human platelet function and ROS-related signaling pathways. Materials and methodsIn collagen-stimulated human platelets, aggregometry, assessment of ROS and Ca2+, immunoblotting, ELISA, flow cytometry, platelet adhesion assay, and assessment of mouse arterial thrombosis were performed in this study. Key findingsSetanaxib inhibited both intracellular and extracellular ROS production in collagen-activated platelets. Additionally, setanaxib significantly inhibited collagen-induced platelet aggregation, P-selectin exposure from α-granule release, and ATP release from dense granules. Setanaxib blocked the specific tyrosine phosphorylation-mediated activation of Syk, LAT, Vav1, and Btk within collagen receptor signaling pathways, leading to reduced activation of PLCγ2, PKC, and Ca2+ mobilization. Setanaxib also inhibited collagen-induced activation of integrin αIIbβ3, which is linked to increased cGMP levels and VASP phosphorylation. Furthermore, setanaxib suppressed collagen-induced p38 MAPK activation, resulting in decreased phosphorylation of cytosolic PLA2 and reduced TXA2 generation. Setanaxib also inhibited ERK5 activation, affecting the exposure of procoagulant phosphatidylserine. Setanaxib reduced thrombus formation under shear conditions by preventing platelet adhesion to collagen. Finally, in vivo administration of setanaxib in animal models led to the inhibition of arterial thrombosis. SignificanceThis study is the first to show that setanaxib suppresses ROS generation, platelet activation, and collagen-induced thrombus formation, suggesting its potential use in treating thrombotic or cardiovascular diseases.

Abstract C016: Pancreatitis-induced resistance to KRAS targeted therapy: The role of cellular plasticity and underlying mechanisms

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease characterized by cell plasticity, particularly the epithelial-to-mesenchymal transition (EMT) phenotype, which significantly contributes to both pancreatic tumorigenesis and therapy resistance. Chronic pancreatitis, a key risk factor for PDAC, induces fibrosis, recruits macrophages, and elevates TGFβ, an EMT master regulator, in the tumor microenvironment (TME). Despite the observed negative correlation between dependence on oncogenic KRAS signaling and the quasi- mesenchymal (QM) subtype, the role of cellular plasticity and the underlying mechanisms of resistance remain unclear. To address this, we employed genetically engineered mouse models that mimic human pancreatitis and PDAC, alongside an in vitro 3-D tumor spheroid culture system. Our study demonstrates that chronic pancreatitis promotes resistance to KRAS- targeted therapy through a canonical TGFβ signaling pathway-dependent mechanism. Nuclear Factor of Activated T Cells 5 (NFAT5) forms a hetero-pentamer with canonical TGFβ factors SMAD3 and SMAD4, inducing EMT and promoting therapy resistance. Analysis of human samples indicates a positive correlation between NFAT5 expression and pancreatic tumorigenesis, with elevated NFAT5 expression correlating with poorer overall survival in the TCGA PDAC dataset. Functional studies reveal that genetic depletion or chemical inhibition of NFAT5 thwarts resistance to KRAS inhibition induced by TGFβ or pancreatitis, impairs the growth of QM-like escaper tumors, and synergizes with KRAS inhibitors to further suppress tumor growth in pre-clinical models. Mechanistically, we identified the chaperone protein and extracellular matrix regulator S100A4 as a key effector transcriptionally activated by the NFAT5- SMAD complex, mediating therapy resistance partially through the activation of key KRAS downstream MAPK and AKT signaling pathways. Furthermore, our investigation reveals that TGFβ stimulates PDAC cells to secrete the chemokine CCL2, which recruits circulating macrophages. In turn, these macrophages support PDAC cells in bypassing KRAS inhibition through paracrine TGFβ and S100A4. Overall, this study establishes a molecular foundation for KRAS-targeted therapy resistance associated with cellular plasticity in PDAC, highlighting pancreatitis as a potential risk factor, and proposes a novel strategy to overcome this resistance through NFAT5 inhibition or S100A4 blockade. Citation Format: Daiyong Deng, Pingping Hou. Pancreatitis-induced resistance to KRAS targeted therapy: The role of cellular plasticity and underlying mechanisms [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C016.

Exploring the therapeutic potential of rabdoternin E in lung cancer treatment: Targeting the ROS/p38 MAPK/JNK signaling pathway.

Lung cancer has the highest incidence and mortality rates of all cancer types in China and therefore represents a serious threat to human health. In the present study, the mechanism of rabdoternin E against the proliferation of the lung cancer cell line A549 was explored. It was found that rabdoternin E caused the accumulation of large amounts of reactive oxygen species (ROS), promoted cell S phase arrest by reducing the expression of CDK2 and cyclin A2, induced apoptosis by increasing the Bax/Bcl‑2 ratio and promoted the phosphorylation of proteins in the ROS/p38 MAPK/JNK signaling pathway, which is associated with apoptosis and ferroptosis. In addition, it was also found that Z‑VAD‑FMK (an apoptosis inhibitor), ferrostatin‑1 (ferroptosis inhibitor) and N‑acetylcysteine (a ROS inhibitor) could partially or greatly reverse the cytotoxicity of rabdoternin E to A549 cells. Similarly, NAC (N‑acetylcysteine) treatment notably inhibited the rabdoternin E‑stimulated p38 MAPK and JNK activation. Furthermore, in vivo experiments in mice revealed that Rabdoternin E markedly reduced tumor volume and weight and regulated the expression levels of apoptosis and ferroptosis‑related proteins (including Ki67, Bcl‑2, Bax, glutathione peroxidase 4, solute carrier family 7 member 11 and transferrin) in the tumor tissues of mice. Histopathological observation confirmed that the number of tumor cells decreased markedly after administration of rabdoternin E. Taken together, rabdoternin E induced apoptosis and ferroptosis of A549 cells by activating the ROS/p38 MAPK/JNK signaling pathway. Therefore, the results of the present study showed that rabdoternin E is not toxic to MCF‑7 cells (normal lung cells), had no significant effect on body weight and was effective and therefore may be a novel therapeutic treatment for lung cancer.

Identification of novel candidate predisposing genes in familial nonmedullary thyroid carcinoma implicating DNA damage repair pathways.

The genetic basis of nonsyndromic familial nonmedullary thyroid carcinoma (FNMTC) is still poorly understood, as the susceptibility genes identified so far only account for a small percentage of the genetic burden. Recently, germline mutations in DNA repair-related genes have been reported in cases with thyroid cancer. In order to clarify the genetic basis of FNMTC, 94 genes involved in hereditary cancer predisposition, including DNA repair genes, were analyzed in 48 probands from FNMTC families, through targeted next-generation sequencing (NGS). Genetic variants were selected upon bioinformatics analysis and in silico studies. Structural modeling and network analysis were also performed. In silico results of NGS data unveiled likely pathogenic germline variants in 15 families with FNMTC, in genes encoding proteins involved in DNA repair (ATM, CHEK2, ERCC2, BRCA2, ERCC4, FANCA, FANCD2, FANCF, and PALB2) and in the DICER1, FLCN, PTCH1, BUB1B, and RHBDF2 genes. Structural modeling predicted that most missense variants resulted in the disruption of networks of interactions between residues, with implications for local secondary and tertiary structure elements. Functional annotation and network analyses showed that the involved DNA repair proteins functionally interact with each other, within the same DNA repair pathway and across different pathways. MAPK activation was a common event in tumor progression. This study supports that rare germline variants in DNA repair genes may be accountable for FNMTC susceptibility, with potential future utility in patients' clinical management, and reinforces the relevance of DICER1 in disease etiology.

An inducible sphingosine kinase 1 in hepatic stellate cells potentiates liver fibrosis

Hepatic stellate cells (HSCs) play a role in hepatic fibrosis and sphingosine kinase (SphK) is involved in biological processes. As studies on the regulatory mechanisms and functions of SphK in HSCs during liver fibrosis are currently limited, this study aimed to elucidate the regulatory mechanism and connected pathways of SphK upon HSC activation. The expression of SphK1 was higher in HSCs than in hepatocytes, and upregulated in activated primary HSCs. SphK1 was also increased in liver homogenates of carbon tetrachloride-treated or bile duct ligated mice and in transforming growth factor-β (TGF-β)-treated LX-2 cells. TGF-β-mediated SphK1 induction was due to Smad3 signaling in LX-2 cells. SphK1 modulation altered the expression of liver fibrogenesis-related genes. This SphK1-mediated profibrogenic effect was dependent on SphK1/sphingosine-1-phosphate/sphingosine-1-phosphate receptor signaling through ERK. Epigallocatechin gallate blocked TGF-β-induced SphK1 expression and hepatic fibrogenesis by attenuating Smad and MAPK activation. SphK1 induced by TGF-β facilitates HSC activation and liver fibrogenesis, which is reversed by epigallocatechin gallate. Accordingly, SphK1 and related signal transduction may be utilized to treat liver fibrosis.

The Pigmentation of Blue Light Is Mediated by Both Melanogenesis Activation and Autophagy Inhibition through OPN3–TRPV1

Blue light, a high-energy radiation in the visible light spectrum, was recently reported to induce skin pigmentation. In this study, we investigated the involvement of TRPV1-mediated signaling along with OPN3 in blue light-induced melanogenesis, as well as its signaling pathway. Operating downstream target of OPN3 in blue light-induced melanogenesis, blue light activated TRPV1 and upregulated its expression, resulting in calcium influx. [Ca2+] induced activation of CaMKII and MAPK. It also downregulated clusterin expression, leading to the nuclear translocation of PAX3, ultimately affecting melanin synthesis. In addition, blue light interfered with autophagy-mediated regulation of melanosomes by decreasing not only the interaction between CLU and LC3B but the expression of ATF family. These findings demonstrate that the pigmenting effects of blue light are mediated by CaMKII- and MAPK-mediated signaling, as well as CLU-dependent inhibition of autophagy through OPN3-TRPV1-calcium influx, suggesting a new signaling pathway by which blue light regulates melanocyte biology. Furthermore, these results suggest that TRPV1 and CLU could be potential therapeutic targets for blue light-induced pigmentation due to prolonged exposure to blue light.