NSC 95397 Suppresses Proliferation and Induces Apoptosis in Colon Cancer Cells through MKP-1 and the ERK1/2 Pathway

NSC95397 Is a Novel HIV-1 Latency-Reversing Agent

The latent viral reservoir represents one of the major barriers to curing HIV-1. Focus on the "kick and kill" (also called "shock and kill") approach, in which virus expression is reactivated, and then cells producing virus are selectively depleted, has led to the discovery of many latency-reversing agents (LRAs) that have furthered our understanding of the mechanisms driving HIV-1 latency and latency reversal. Thus far, individual compounds have yet to be robust enough to work as a therapy, highlighting the importance of identifying new compounds that target novel pathways and synergize with known LRAs. In this study, we identified a promising LRA, NSC95397, from a screen of ~4250 compounds. We validated that NSC95397 reactivates latent viral transcription and protein expression from cells with unique integration events and across different latency models. Co-treating cells with NSC95397 and known LRAs demonstrated that NSC95397 synergizes with different drugs under both standard normoxic and physiological hypoxic conditions. NSC95397 does not globally increase open chromatin, and bulk RNA sequencing revealed that NSC95397 does not greatly increase cellular transcription. Instead, NSC95397 downregulates pathways key to metabolism, cell growth, and DNA repair-highlighting the potential of these pathways in regulating HIV-1 latency. Overall, we identified NSC95397 as a novel LRA that does not largely alter global transcription, shows potential for synergy with known LRAs, and may act through novel pathways not previously recognized for their ability to modulate HIV-1 latency.

Nr1d1 inhibition mitigates intermittent hypoxia-induced pulmonary hypertension via Dusp1-mediated Erk1/2 deactivation and mitochondrial fission attenuation

Intermittent hypoxia (IH) precipitates pulmonary vasoconstriction, culminating in the onset of pulmonary hypertension (PH) among individuals afflicted with sleep apnea. While Nuclear receptor subfamily 1 group D member 1 (Nr1d1) is progressively recognized as pivotal regulator of cellular physiology, the role in the pathogenesis of IH-induced PH remains largely uncharted. The expression of Nr1d1 was examined in IH-induced rodent PH and in IH-treated PASMCs. To elucidate the contribution of Nr1d1 to the development of IH-induced PH, we employed siRNA to modulate Nr1d1 expression in vitro and employed serotype 1 adeno-associated virus (AAV1) in vivo. Nr1d1 levels were elevated in IH-induced rodents PH lung tissues and IH-treated PASMCs. Knocking down Nr1d1 by AAV1 effectively inhibited PH progression in chronic IH-induced PH models. Mechanistic investigations identified dual specificity phosphatase 1 (Dusp1), as a direct target that Nr1d1 trans-repressed, mediating Nr1d1's regulatory influence on Erk1/2/Drp1 signaling. Nr1d1 deficiency ameliorates mitochondrial dysfunction and fission by restoring Dusp1 dysregulation and Drp1 phosphorylation. Activation of Erk1/2 with PMA reversed the Dusp1-mediated regulation of Drp1 phosphorylation, indicating the involvement of the Erk1/2 pathway in Drp1 phosphorylation controlled by Dusp1. Meanwhile, intermittent hypoxia induced more severe PH in Dusp1 knockout mice compared with wild-type mice. Our data unveil a novel role for Nr1d1 in IH-induced PH pathogenesis and an undisclosed Nr1d1-Dusp1 axis in PASMCs mitochondrial fission regulation.

NSC95397 is a Novel HIV-1 Latency Reversing Agent

The latent viral reservoir represents one of the major barriers of curing HIV-1. Focus on the "kick and kill" approach, in which virus expression is reactivated then cells producing virus are selectively depleted, has led to the discovery of many latency reversing agents (LRAs) that have furthered our understanding of the mechanisms driving HIV-1 latency and latency reversal. Thus far, individual compounds have yet to be robust enough to work as a therapy, highlighting the importance of identifying new compounds that target novel pathways and synergize with known LRAs. In this study, we identified a promising LRA, NSC95397, from a screen of ~4250 compounds. We validated that NSC95397 reactivates latent viral transcription and protein expression from cells with unique integration events and across different latency models. Co-treating cells with NSC95397 and known LRAs demonstrated that NSC95397 synergizes with different drugs under both standard normoxic and physiological hypoxic conditions. NSC95397 does not globally increase open chromatin, and bulk RNA sequencing revealed NSC95397 does not greatly increase cellular transcription. Instead, NSC95397 downregulates pathways key to metabolism, cell growth, and DNA repair - highlighting the potential of these pathways in regulating HIV-1 latency. Overall, we identified NSC95397 as a novel LRA that does not largely alter global transcription, that shows potential for synergy with known LRAs, and that may act through novel pathways not previously recognized for their ability to modulate HIV-1 latency.

β2-microglobulin induced apoptosis of tumor cells via the ERK signaling pathway by directly interacting with HFE in HER2-overexpressing breast cancer

BACKGROUND

Our previous study demonstrated that β2-microglobulin (β2M) promoted ER+/HER2- breast cancer survival via the SGK1/Bcl-2 signaling pathway. However, the role of β2M has not been investigated in ER-/HER2+ breast cancer. Here, we aimed to determine the role of β2M in ER-/HER2+ breast cancer.

METHODS

The interaction between β2M and HFE was confirmed by co-immunoprecipitation, mass spectrometry, yeast two-hybrid screening, and His pull-down. The knockdown and overexpression of β2M or HFE were performed in MDA-MB-453 cells, and ERK signaling pathway was subsequently analyzed via western blotting. Apoptotic cells were detected using flow cytometer. β2M, HFE, and p-ERK1/2 were examined in tumor and paired adjacent tissues via immunohistochemistry.

RESULTS

HFE was found to be an interacting protein of β2M in ER-/HER2+ breast cancer cells MDA-MB-453 by co-immunoprecipitation and mass spectrometry. A yeast two-hybrid system and His-pull down experiments verified that β2M directly interacted with HFE. β2M and HFE as a complex were mainly located in the cytoplasm, with some on the cytomembrane of MDA-MB-453 cells. In addition to breast cancer cells BT474, endogenous β2M directly interacted with HFE in breast cancer cells MDA-MB-453, MDA-MB-231, and MCF-7. β2M activated the ERK signaling pathway by interacting with HFE and induced apoptosis of MDA-MB-453 cells. The expression of HFE and p-ERK1/2 showed significantly high levels in HER2-overexpressing breast cancer tumor tissue compared with adjacent normal tissue, consistent with the results obtained from the cell experiments.

CONCLUSIONS

β2M induced apoptosis of tumor cells via activation of the ERK signal pathway by directly interacting with HFE in HER2-overexpressing breast cancer.

Potential of CDC25 phosphatases in cancer research and treatment: key to precision medicine

The global burden of cancer continues to rise, underscoring the urgency of developing more effective and precisely targeted therapies. This comprehensive review explores the confluence of precision medicine and CDC25 phosphatases in the context of cancer research. Precision medicine, alternatively referred to as customized medicine, aims to customize medical interventions by taking into account the genetic, genomic, and epigenetic characteristics of individual patients. The identification of particular genetic and molecular drivers driving cancer helps both diagnostic accuracy and treatment selection. Precision medicine utilizes sophisticated technology such as genome sequencing and bioinformatics to elucidate genetic differences that underlie the proliferation of cancer cells, hence facilitating the development of customized therapeutic interventions. CDC25 phosphatases, which play a crucial role in governing the progression of the cell cycle, have garnered significant attention as potential targets for cancer treatment. The dysregulation of CDC25 is a characteristic feature observed in various types of malignancies, hence classifying them as proto-oncogenes. The proteins in question, which operate as phosphatases, play a role in the activation of Cyclin-dependent kinases (CDKs), so promoting the advancement of the cell cycle. CDC25 inhibitors demonstrate potential as therapeutic drugs for cancer treatment by specifically blocking the activity of CDKs and modulating the cell cycle in malignant cells. In brief, precision medicine presents a potentially fruitful option for augmenting cancer research, diagnosis, and treatment, with an emphasis on individualized care predicated upon patients' genetic and molecular profiles. The review highlights the significance of CDC25 phosphatases in the advancement of cancer and identifies them as promising candidates for therapeutic intervention. This statement underscores the significance of doing thorough molecular profiling in order to uncover the complex molecular characteristics of cancer cells.

Multiple Sclerosis: New Insights into Molecular Pathogenesis and Novel Platforms for Disease Treatment

BACKGROUND

Multiple sclerosis (MS), a chronic inflammatory disorder, affects the central nervous system via myelin degradation. The cause of MS is not fully known, but during recent years, our knowledge has deepened significantly regarding the different aspects of MS, including etiology, molecular pathophysiology, diagnosis and therapeutic options. Myelin basic protein (MBP) is the main myelin protein that accounts for maintaining the stability of the myelin sheath. Recent evidence has revealed that MBP citrullination or deamination, which is catalyzed by Ca2+ dependent peptidyl arginine deiminase (PAD) enzyme leads to the reduction of positive charge, and subsequently proteolytic cleavage of MBP. The overexpression of PAD2 in the brains of MS patients plays an essential role in new epitope formation and progression of the autoimmune disorder. Some drugs have recently entered phase III clinical trials with promising efficacy and will probably obtain approval in the near future. As different therapeutic platforms develop, finding an optimal treatment for each individual patient will be more challenging.

AIMS

This review provides a comprehensive insight into MS with a focus on its pathogenesis and recent advances in diagnostic methods and its present and upcoming treatment modalities.

CONCLUSION

MS therapy alters quickly as research findings and therapeutic options surrounding MS expand. McDonald's guidelines have created different criteria for MS diagnosis. In recent years, ever-growing interest in the development of PAD inhibitors has led to the generation of many reversible and irreversible PAD inhibitors against the disease with satisfactory therapeutic outcomes.

Isolinderalactone Induces Apoptosis, Autophagy, Cell Cycle Arrest and MAPK Activation through ROS-Mediated Signaling in Colorectal Cancer Cell Lines

Colorectal cancer (CRC) is one of the most common malignancies worldwide. Isolinderalactone (ILL), a sesquiterpene isolated from the root extract of Lindera aggregata, has been reported to exhibit anti-proliferative and anti-metastatic activities in various cancer cell lines. However, the mechanisms associated with its antitumor effects on CRC cells remain unclear. ILL treatment significantly suppressed proliferation and induced cell cycle G2/M arrest in CRC cells by inhibiting the expression of cyclin B, p-cdc2, and p-cdc25c and up-regulating the expression of p21. In addition, ILL induced mitochondria-associated apoptosis through the up-regulation of cleaved -caspase-9 and -3 expression. ILL induced autophagy by increasing the levels of LC3B in CRC cells, which was partially rescued by treatment with an autophagy inhibitor (chloroquine). Furthermore, ILL increases the accumulation of reactive oxygen species (ROS) and activates the MAPK pathway. Application of the ROS scavenger, N-acetyl cysteine (NAC), effectively inhibited ILL toxicity and reversed ILL-induced apoptosis, cell cycle arrest, autophagy, and ERK activation. Taken together, these results suggest that ILL induces G2/M phase arrest, apoptosis, and autophagy and activates the MAPK pathway via ROS-mediated signaling in human CRC cells.

Low let-7d microRNA levels in chick embryos enhance innate immunity against Mycoplasma gallisepticum by suppressing the mitogen-activated protein kinase pathway

Chick embryos are a valuable model for studying immunity and vaccines. Therefore, it is crucial to investigate the molecular mechanism of the Mycoplasma gallisepticum (MG)-induced immune response in chick embryos for the prevention and control of MG. In this study, we screened for downregulated let-7d microRNA in MG-infected chicken embryonic lungs to explore its involvement in the innate immune mechanism against MG. Here, we demonstrated that low levels of let-7d are a protective mechanism for chicken embryo primary type II pneumocytes (CP-II) in the presence of MG. Specifically, we found that depressed levels of let-7 in CP-II cells reduced the adhesion capacity of MG. This suppressive effect was achieved through the activated mitogen-activated protein kinase phosphatase 1 (MKP1) target gene and the inactivated mitogen-activated protein kinase (MAPK) pathway. Furthermore, MG-induced hyperinflammation and cell death were both alleviated by downregulation of let-7d. In conclusion, chick embryos protect themselves against MG infection through the innate immune molecule let-7d, which may result from its function as an inhibitor of the MAPK pathway to effectively mitigate MG adhesion, the inflammatory response and cell apoptosis. This study may provide new insight into the development of vaccines against MG.

Eriocitrin attenuates sepsis-induced acute lung injury in mice by regulating MKP1/MAPK pathway mediated-glycolysis

Metabolic reprogramming has been shown to aggravate sepsis-induced acute lung injury. In particular, enhanced glycolysis is closely associated with inflammation and oxidative stress. Eriocitrin (ERI) is a natural flavonoid found in citrus fruit that exhibits various pharmacological activities, with antioxidant, anti-inflammatory, anti-diabetic, and anti-tumor properties. However, the role of ERI in lung injury is not well understood. We established a septic mouse model of acute lung injury (ALI) using lipopolysaccharide (LPS) for induction. Primary peritoneal macrophages were isolated to verify the relevant molecular mechanism. Tissues were assessed for lung pathology, pro-inflammatory cytokines, markers of oxidative stress, and protein and mRNA expression levels. In vivo experiments showed that ERI effectively alleviated LPS-induced pathological injury, suppress the inflammatory response (TNF-α, IL-1β, IL-6 levels) and decreased oxidative stress (MDA, ROS) in murine lung tissue. In vitro, ERI increased the resistance of LPS-treated cells to excessive inflammation and oxidative stress by inhibiting the enhancement of glycolysis (indicated by expression levels of HIF-1α, HK2, LDHA, PFKFB3, and PKM2). Specifically, the beneficial effects of ERI following LPS-induced lung injury occurred through promoting the expression of MKP1, which mediates the inactivation of the MAPK pathway to inhibit enhanced glycolysis. These results demonstrate that ERI has a protective effect on sepsis-induced ALI by regulating MKP1/MAPK pathway mediated-glycolysis. Hence, ERI is a promising candidate against ALI via inhibiting glycolysis.

Peptidylarginine deiminase enzymes and citrullinated proteins in female reproductive physiology and associated diseases†

Citrullination, the post-translational modification of arginine residues, is catalyzed by the four catalytically active peptidylarginine deiminase (PAD or PADI) isozymes and alters charge to affect target protein structure and function. PADs were initially characterized in rodent uteri and, since then, have been described in other female tissues including ovaries, breast, and the lactotrope and gonadotrope cells of the anterior pituitary gland. In these tissues and cells, estrogen robustly stimulates PAD expression resulting in changes in levels over the course of the female reproductive cycle. The best-characterized targets for PADs are arginine residues in histone tails, which, when citrullinated, alter chromatin structure and gene expression. Methodological advances have allowed for the identification of tissue-specific citrullinomes, which reveal that PADs citrullinate a wide range of enzymes and structural proteins to alter cell function. In contrast to their important physiological roles, PADs and citrullinated proteins are also involved in several female-specific diseases including autoimmune disorders and reproductive cancers. Herein, we review current knowledge regarding PAD expression and function and highlight the role of protein citrullination in both normal female reproductive tissues and associated diseases.

Gallic acid suppresses the progression of triple-negative breast cancer HCC1806 cells via modulating PI3K/AKT/EGFR and MAPK signaling pathways

Triple-negative breast cancer (TNBC) is a severe threat to women's health because of its aggressive nature, early age of onset, and high recurrence rate. Therefore, in this study, we aimed to evaluate the anti-tumor effects of Gallic acid (GA) on the TNBC HCC1806 cells in vitro. The cell proliferation was detected by MTT and plate clone formation assays, cell apoptosis, cell cycle, and mitochondrial membrane potential (MMP) were analyzed by flow cytometry and Hoechst 33258 staining assays, and the intracellular reactive oxygen species (ROS) accumulation were also investigated. Real-Time PCR and western blot were examined to explore the mechanism of action. The results indicated that GA suppressed HCC1806 cells proliferation and promoted HCC1806 cells apoptosis. Meanwhile, GA treatment changed the morphology of the HCC1806 cells. In addition, GA blocked the HCC1806 cells cycle in the S phase, and it induced cells apoptosis accompanied by ROS accumulation and MMP depolarization. Real-Time PCR results suggested that GA increased Bax, Caspase-3, Caspase-9, P53, JINK and P38 mRNA expression, and decreased Bcl-2, PI3K, AKT and EGFR mRNA expression. Western blotting results suggested that GA increased Bax, cleaved-Caspase-3, cleaved-Caspase-9, P53, P-ERK1/2, P-JNK, P-P38 proteins expression, and decreased Bcl-2, P-PI3K, P-AKT, P-EGFR proteins expression. Furthermore, molecular docking suggested that GA has the high affinity for PI3K, AKT, EGFR, ERK1/2, JNK, and P38. In conclusion, GA could suppress HCC1806 cells proliferation and promote HCC1806 cells apoptosis through the mitochondrial apoptosis pathway and induces ROS generation which further inhibits PI3K/AKT/EGFR and activates MAPK signaling pathways. Our study will provide some new references for using GA in the treatment of TNBC.

Citrullination in the pathology of inflammatory and autoimmune disorders: recent advances and future perspectives

Numerous post-translational modifications (PTMs) govern the collective metabolism of a cell through altering the structure and functions of proteins. The action of the most prevalent PTMs, encompassing phosphorylation, methylation, acylations, ubiquitination and glycosylation is well documented. A less explored protein PTM, conversion of peptidylarginine to citrulline, is the subject of this review. The process of citrullination is catalysed by peptidylarginine deiminases (PADs), a family of conserved enzymes expressed in a variety of human tissues. Accumulating evidence suggest that citrullination plays a significant role in regulating cellular metabolism and gene expression by affecting a multitude of pathways and modulating the chromatin status. Here, we will discuss the biochemical nature of arginine citrullination, the enzymatic machinery behind it and also provide information on the pathological consequences of citrullination in the development of inflammatory diseases (rheumatoid arthritis, multiple sclerosis, psoriasis, systemic lupus erythematosus, periodontitis and COVID-19), cancer and thromboembolism. Finally, developments on inhibitors against protein citrullination and recent clinical trials providing a promising therapeutic approach to inflammatory disease by targeting citrullination are discussed.

High-throughput virtual screening and preclinical analysis identifies CB-1, a novel potent dual B-Raf/c-Raf inhibitor, effective against wild and mutant variants of B-Raf expression in colorectal carcinoma

Paradoxical Raf activation via Raf dimerization is a major drawback of wild/mutant B-Raf inhibitors. Herein, we report that CB-1 a novel, potent B-Raf/c-Raf dual inhibitor, effective against colon cancer cells, irrespective of their genetic status. High-throughput virtual screening of the ChemBridge library against wild B-Raf (B-Raf^WT), mutant B-Raf (B-Raf^V600E), and c-Raf was performed using an automated protocol with the AutoDock-VINA. Caco-2 and HT-29 cells were used. Of the 23,365 compounds screened computationally, CB-1 showed the highest binding energy towards B-Raf^WT with a ΔG_binding score of - 13.0 kcal/mol. The compound was also predicted to be effective against B-Raf^V600E and c-Raf molecules with ΔG_binding energies of - 10.6 and - 10.1 kcal/mol, respectively. The compound inhibited B-Raf^WT, B-Raf^V600E and c-Raf kinases with IC₅₀ values of 27.13, 51.70, and 40.23 nM, respectively. The GI₅₀ value of CB-1 was 247.9 nM in B-Raf^WT-expressing Caco-2 cells and 352.4 nM in B-RafV600E-expressing HT-29 cells. Dose-dependent increases in total apoptosis and G₁ cell cycle phase arrest was observed in CB-1-treated colon cancer cells. The compound decreased B-Raf expression in both wild and mutant colon cancer cells. CB-1, a novel, potent dual B-Raf/c-Raf inhibitor was effective against colon cancer cells bearing wild-type and mutant variants of B-Raf expression.

ERK: A Double-Edged Sword in Cancer. ERK-Dependent Apoptosis as a Potential Therapeutic Strategy for Cancer

The RAF/MEK/ERK signaling pathway regulates diverse cellular processes as exemplified by cell proliferation, differentiation, motility, and survival. Activation of ERK1/2 generally promotes cell proliferation, and its deregulated activity is a hallmark of many cancers. Therefore, components and regulators of the ERK pathway are considered potential therapeutic targets for cancer, and inhibitors of this pathway, including some MEK and BRAF inhibitors, are already being used in the clinic. Notably, ERK1/2 kinases also have pro-apoptotic functions under certain conditions and enhanced ERK1/2 signaling can cause tumor cell death. Although the repertoire of the compounds which mediate ERK activation and apoptosis is expanding, and various anti-cancer compounds induce ERK activation while exerting their anti-proliferative effects, the mechanisms underlying ERK1/2-mediated cell death are still vague. Recent studies highlight the importance of dual-specificity phosphatases (DUSPs) in determining the pro- versus anti-apoptotic function of ERK in cancer. In this review, we will summarize the recent major findings in understanding the role of ERK in apoptosis, focusing on the major compounds mediating ERK-dependent apoptosis. Studies that further define the molecular targets of these compounds relevant to cell death will be essential to harnessing these compounds for developing effective cancer treatments.

The transrepression and transactivation roles of CtBPs in the pathogenesis of different diseases

Gene transcription is strictly controlled by transcriptional complexes, which are assemblies of transcription factors, transcriptional regulators, and co-regulators. Mammalian genomes encode two C-terminal-binding proteins (CtBPs), CtBP1 and CtBP2, which are both well-known transcriptional corepressors of oncogenic processes. Their overexpression in tumors is associated with malignant behavior, such as uncontrolled cell proliferation, migration, and invasion, as well as with an increase in the epithelial-mesenchymal transition. CtBPs coordinate with other transcriptional regulators, such as histone deacetylases (HDACs) and histone acetyltransferases (p300 and CBP [CREBP-binding protein]) that contain the PXDLS motif, and with transcription factors to assemble transcriptional complexes that dock onto the promoters of genes to initiate gene transcription. Emerging evidence suggests that CtBPs function as both corepressors and coactivators in different biological processes ranging from apoptosis to inflammation and osteogenesis. Therapeutic targeting of CtBPs or the interactions required to form transcriptional complexes has also shown promising effects in preventing disease progression. This review summarizes the most recent progress in the study of CtBP functions and therapeutic inhibitors in different biological processes. This knowledge may enable a better understanding of the complexity of the roles of CtBPs, while providing new insights into therapeutic strategies that target CtBPs.

Transcriptome analysis of potential candidate genes and molecular pathways in colitis-associated colorectal cancer of Mkp-1-deficient mice

BACKGROUND

The nuclear phosphatase mitogen-activate protein kinase phosphatase-1 (MKP-1) is a key negative regulator of the innate immune response through the regulation of the biosynthesis of proinflammatory cytokines. In colorectal cancer (CRC), which is induced mainly by chronic inflammation, Mkp-1 overexpression was found in addition to disturbances in Mkp-1 functions, which may play a role in cancer development in different types of tumors. However, the potential molecular mechanisms by which Mkp-1 influences CRC development is not clear. Here, we performed global gene expression profiling of Mkp-1 KO mice using RNA sequencing (RNA-seq) to explore the role of Mkp-1 in CRC progression using transcriptome analysis.

METHODS

Azoxymethane/dextran sodium sulfate (AOM/DSS) mouse models were used to examine the most dramatic molecular and signaling changes that occur during different phases of CRC development in wild-type mice and Mkp-1 KO mice. Comprehensive bioinformatics analyses were used to elucidate the molecular processes regulated by Mkp-1. Differentially expressed genes (DEGs) were identified and functionally analyzed by Gene Ontology (GO), Kyoto Enrichment of Genes and Genomes (KEGG). Then, protein-protein interaction (PPI) network analysis was conducted using the STRING database and Cytoscape software.

RESULTS

Persistent DEGs were different in adenoma and carcinoma stage (238 & 251, respectively) and in WT and MKp-1 KO mice (221& 196, respectively). Mkp-1 KO modulated key molecular processes typically activated in cancer, in particular, cell adhesion, ion transport, extracellular matrix organization, response to drug, response to hypoxia, and response to toxic substance. It was obvious that these pathways are closely associated with cancer development and metastasis. From the PPI network analyses, nine hub genes associated with CRC were identified.

CONCLUSION

These findings suggest that MKp-1 and its hub genes may play a critical role in cancer development, prognosis, and determining treatment outcomes. We provide clues to build a potential link between Mkp-1 and colitis-associated tumorigenesis and identify areas requiring further investigation.

GPER-Induced ERK Signaling Decreases Cell Viability of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is an aggressive malignancy with a poor prognosis. Effective biomarkers and specific therapeutic targets for HCC are therefore urgently needed. G protein-coupled estrogen receptor (GPER) plays a crucial role in numerous cancer types; however, its functions in HCC require further exploration. In the present study, we found a remarkable difference in GPER staining between tumor tissue (100/141, 70.9%) and matched non-tumor tissue (27/30, 90.0%). Compared with the GPER-negative patients, the GPER-positive patients with HCC were closely associated with female sex, negative hepatitis B surface antigen, small tumor size, low serum alpha fetoprotein level, and longer overall survival. Treatment with GPER-specific agonist G1 led to the sustained and transient activation of the EGFR/ERK and EGFR/AKT signaling pathways, respectively, in the HCC cell lines HCCLM3 and SMMC-7721, which express high levels of GPER. Interestingly, G1-induced EGFR/ERK signaling, rather than EGFR/AKT signaling mediated by GPER, was involved in decreasing cell viability by blocking cell cycle progression, thereby promoting apoptosis and inhibiting cell growth. Clinical analysis indicated that simultaneous high expression of GPER and phosphorylated-ERK (p-ERK) predicted improved prognosis for HCC. Finally, the activation of GPER/ERK signaling remarkably suppressed tumor growth in an HCC xenograft model, and this result was consistent with the in vitro data. Our findings suggest that specific activation of the GPER/ERK axis may serve as a novel tumor-suppressive mechanism and that this axis could be a therapeutic target for HCC.

The anti-fibrotic actions of relaxin are mediated through AT2 R-associated protein phosphatases via RXFP1-AT2 R functional crosstalk in human cardiac myofibroblasts

Fibrosis is a hallmark of several cardiovascular diseases. The relaxin family peptide receptor 1 (RXFP1) agonist, relaxin, has rapidly occurring anti-fibrotic actions which are mediated through RXFP1 and angiotensin II receptor crosstalk on renal and cardiac myofibroblasts. Here, we investigated whether this would allow relaxin to indirectly activate angiotensin II type 2 receptor (AT₂ R)-specific signal transduction in primary human cardiac myofibroblasts (HCMFs). The anti-fibrotic effects of recombinant human relaxin (RLX; 16.8 nM) or the AT₂ R-agonist, Compound 21 (C21; 1 μM), were evaluated in TGF-β1-stimulated HCMFs, in the absence or presence of an RXFP1 antagonist (1 μM) or AT₂ R antagonist (0.1 μM) to confirm RXFP1-AT₂ R crosstalk. Competition binding for RXFP1 was determined. Western blotting was performed to determine which AT₂ R-specific protein phosphatases were expressed by HCMFs; then, the anti-fibrotic effects of RLX and/or C21 were evaluated in the absence or presence of pharmacological inhibition (NSC95397 (1 μM) for MKP-1; okadaic acid (10 nM) for PP2A) or siRNA-knockdown of these phosphatases after 72 hours. The RLX- or C21-induced increase in ERK1/2 and nNOS phosphorylation, and decrease in α-SMA (myofibroblast differentiation) and collagen-I expression by HCMFs was abrogated by pharmacological blockade of RXFP1 or the AT₂ R, confirming RXFP1-AT₂ R crosstalk in these cells. HCMFs were found to express AT₂ R-dependent MKP-1 and PP2A phosphatases, while pharmacological blockade or siRNA-knockdown of either phosphatase also abolished RLX and/or C21 signal transduction in HCMFs (all P < .05 vs RLX or C21 alone). These findings demonstrated that RLX can indirectly activate AT₂ R-dependent phosphatase activity in HCMFs by signaling through RXFP1-AT₂ R crosstalk, which have important therapeutic implications for its anti-fibrotic actions.

Understanding MAPK Signaling Pathways in Apoptosis

MAPK (mitogen-activated protein kinase) signaling pathways regulate a variety of biological processes through multiple cellular mechanisms. In most of these processes, such as apoptosis, MAPKs have a dual role since they can act as activators or inhibitors, depending on the cell type and the stimulus. In this review, we present the main pro- and anti-apoptotic mechanisms regulated by MAPKs, as well as the crosstalk observed between some MAPKs. We also describe the basic signaling properties of MAPKs (ultrasensitivity, hysteresis, digital response), and the presence of different positive feedback loops in apoptosis. We provide a simple guide to predict MAPKs’ behavior, based on the intensity and duration of the stimulus. Finally, we consider the role of MAPKs in osmostress-induced apoptosis by using Xenopus oocytes as a cell model. As we will see, apoptosis is plagued with multiple positive feedback loops. We hope this review will help to understand how MAPK signaling pathways engage irreversible cellular decisions.

A Comprehensive Review on MAPK: A Promising Therapeutic Target in Cancer

The mitogen-activated protein kinase (MAPK) pathway is an important bridge in the switch from extracellular signals to intracellular responses. Alterations of signaling cascades are found in various diseases, including cancer, as a result of genetic and epigenetic changes. Numerous studies focused on both the homeostatic and the pathologic conduct of MAPK signaling; however, there is still much to be deciphered in terms of regulation and action models in both preclinical and clinical research. MAPK has implications in the response to cancer therapy, particularly the activation of the compensatory pathways in response to experimental MAPK inhibition. The present paper discusses new insights into MAPK as a complex cell signaling pathway with roles in the sustenance of cellular normal conduit, response to cancer therapy, and activation of compensatory pathways. Unfortunately, most MAPK inhibitors trigger resistance due to the activation of compensatory feed-back loops in tumor cells and tumor microenvironment components. Therefore, novel combinatorial therapies have to be implemented for cancer management in order to restrict the possibility of alternative pathway activation, as a perspective for developing novel therapies based on integration in translational studies.

BZD9L1 sirtuin inhibitor as a potential adjuvant for sensitization of colorectal cancer cells to 5-fluorouracil

Background:

This study aims to investigate the combination effect of a novel sirtuin inhibitor (BZD9L1) with 5-fluorouracil (5-FU) and to determine its molecular mechanism of action in colorectal cancer (CRC).

Methods:

BZD9L1 and 5-FU either as single treatment or in combination were tested against CRC cells to evaluate synergism in cytotoxicity, senescence and formation of micronucleus, cell cycle and apoptosis, as well as the regulation of related molecular players. The effects of combined treatments at different doses on stress and apoptosis, migration, invasion and cell death mechanism were evaluated through two-dimensional and three-dimensional cultures. In vivo studies include investigation on the combination effects of BZD9L1 and 5-FU on colorectal tumour xenograft growth and an evaluation of tumour proliferation and apoptosis using immunohistochemistry.

Results:

Combination treatments exerted synergistic reduction on cell viability on HCT 116 cells but not on HT-29 cells. Combined treatments reduced survival, induced cell cycle arrest, apoptosis, senescence and micronucleation in HCT 116 cells through modulation of multiple responsible molecular players and apoptosis pathways, with no effect in epithelial mesenchymal transition (EMT). Combination treatments regulated SIRT1 and SIRT2 protein expression levels differently and changed SIRT2 protein localization. Combined treatment reduced growth, migration, invasion and viability of HCT 116 spheroids through apoptosis, when compared with the single treatment. In addition, combined treatment was found to reduce tumour growth in vivo through reduction of tumour proliferation and necrosis compared with the vehicle control group. This highlights the potential therapeutic effects of BZD9L1 and 5-FU towards CRC.

Conclusion:

This study may pave the way for use of BZD9L1 as an adjuvant to 5-FU in improving the therapeutic efficacy for the treatment of colorectal cancer.

Synthesis, anticancer activity, and molecular modeling of 1,4-naphthoquinones that inhibit MKK7 and Cdc25

Cell division cycle 25 (Cdc25) and mitogen-activated protein kinase kinase 7 (MKK7) are enzymes involved in intracellular signaling but can also contribute to tumorigenesis. We synthesized and characterized the biological activity of 1,4-naphthoquinones structurally similar to reported Cdc25 and(or) MKK7 inhibitors with anticancer activity. Compound 7 (3-[(1,4-dioxonaphthalen-2-yl)sulfanyl]propanoic acid) exhibited high binding affinity for MKK7 (K_d = 230 nM), which was greater than the affinity of NSC 95397 (K_d = 1.1 μM). Although plumbagin had a lower binding affinity for MKK7, this compound and sulfur-containing derivatives 4 and 6-8 were potent inhibitors of Cdc25A and Cdc25B. Derivative 22e containing a phenylamino side chain was selective for MKK7 versus MKK4 and Cdc25 A/B, and its isomer 22f was a selective inhibitor of Cdc25 A/B. Docking studies performed on several naphthoquinones highlighted interesting aspects concerning the molecule orientation and hydrogen bonding interactions, which could help to explain the activity of the compounds toward MKK7 and Cdc25B. The most potent naphthoquinone-based inhibitors of MKK7 and/or Cdc25 A/B were also screened for their cytotoxicity against nine cancer cell lines and primary human mononuclear cells, and a correlation was found between Cdc25 A/B inhibitory activity and cytotoxicity of the compounds. Quantum chemical calculations using BP86 and ωB97X-D3 functionals were performed on 20 naphthoquinone derivatives to obtain a set of molecular electronic properties and to correlate these properties with cytotoxic activities. Systematic theoretical DFT calculations with subsequent correlation analysis indicated that energy of the lowest unoccupied molecular orbital E(LUMO), vertical electron affinity (VEA), and reactivity index ω of these molecules were important characteristics related to their cytotoxicity. The reactivity index ω was also a key characteristic related to Cdc25 A/B phosphatase inhibitory activity. Thus, 1,4-naphthoquinones displaying sulfur-containing and phenylamino side chains with additional polar groups could be successfully utilized for further development of efficacious Cdc25 A/B and MKK7 inhibitors with anticancer activity.