Signaling pathways governing the behaviors of leukemia stem cells

Leukemia is a malignancy in the blood that develops from the lymphatic system and bone marrow. Although various treatment options have been used for different types of leukemia, understanding the molecular pathways involved in the development and progression of leukemia is necessary. Recent studies showed that leukemia stem cells (LSCs) play essential roles in the pathogenesis of leukemia by targeting several signaling pathways, including Notch, Wnt, Hedgehog, and STAT3. LSCs are highly proliferative cells that stimulate tumor initiation, migration, EMT, and drug resistance. This review summarizes cellular pathways that stimulate and prevent LSCs' self-renewal, metastasis, and tumorigenesis.

The m6A regulator KIAA1429 stabilizes RAB27B mRNA and promotes the progression of chronic myeloid leukemia and resistance to targeted therapy

Chronic myeloid leukemia (CML) is a common adult leukemia. Both the acute phase of the disease and the adverse effects of anti-cancer treatments can lead to a poor prognosis. The N6-methyladenine (m6A) modification plays an important regulatory role in various physiological and pathological processes. KIAA1429 is a known m6A regulator, but the biological role of KIAA1429 in CML is unclear. In this study, we observed that the m6A levels and KIAA1429 expression were significantly up-regulated in patients with blast phase CML. Notably, KIAA1429 regulated the total level of RNA m6A modification in the CML cells and promoted the malignant biological behaviors of CML cells, including proliferation, migration, and imatinib resistance. Inhibiting KIAA1429 in CML cells reduced the stability of RAB27B mRNA through the m6A/YTHDF1 axis, consequently inhibiting CML proliferation and drug efflux, ultimately increasing the sensitivity of CML cells to imatinib. Moreover, the knockdown of RAB27B also inhibited the proliferation and drug resistance of CML cells and promoted their apoptosis. Rucaparib, a recently developed anti-cancer agent, suppressed the expression of KIAA1429 and CML cell proliferation and promoted cell apoptosis. Rucaparib also inhibited the tumorigenesis of CML cells in vivo. The combined use of rucaparib and imatinib enhanced the sensitivity of CML cells to imatinib. Our study provides evidence that elevated KIAA1429 expression in the blast phase of CML enhances the stability of RAB27B mRNA through the m6A/YTHDF1 axis to up-regulate RAB27B expression, thereby promoting CML progression. Rucaparib exerts inhibitory effects on KIAA1429 expression and thus reduces CML progression.

Echinatin inhibits tumor growth and synergizes with chemotherapeutic agents against human bladder cancer cells by activating p38 and suppressing Wnt/β-catenin pathways

Bladder cancer (BC) is one of the most common malignant tumors in the urinary system. Due to the poor prognosis and high mortality rate of the disease, it is urgent to develop new drugs with high efficacy and low toxicity to treat BC. Echinatin (Ecn) is a bioactive natural flavonoid oflicorice that has attracted special attention for its promising anti-tumor potential. Herein, we explored the inhibitory effects of Echinatin on BC cells and probed the possible molecular mechanism. We found that Ecnin vitro inhibited the proliferation, migration, and invasion, arrested the cell cycle at the G2/M phase, and promoted apoptosis in BC cells. Besides, Ecn had no notable cytotoxicity towards human normal cells. We subsequently confirmed that Ecn restrained xenograft tumor growth and metastasis of BC cells in vivo. Mechanistically, Ecn activated the p38 signaling pathway but inactivated the Wnt/β-catenin signaling pathway, while over-expression of β-catenin and the p38 inhibitor both attenuated the inhibitory effects of Ecn on BC cells. Remarkably, Ecn combined with cisplatin (DDP) or gemcitabine (Gem) had synergistic inhibitory effects on BC cells. In summary, our results validate that Ecn inhibits the tumor growth of human BC cells via p38 and Wnt/β-catenin signaling pathways. More meaningfully, our results suggest a potential strategy to enhance DDP- or Gem-induced inhibitory effects on BC cells by combining with Ecn.

Cellular senescence-driven transcriptional reprogramming of the MAFB/NOTCH3 axis activates the PI3K/AKT pathway and promotes osteosarcoma progression

Osteosarcoma is the most common primary malignancy of bones and primarily occurs in adolescents and young adults. However, a second smaller peak of osteosarcoma incidence was reported in the elderly aged more than 60. Elderly patients with osteosarcoma exhibit different characteristics compared to young patients, which usually results in a poor prognosis. The mechanism underlying osteosarcoma development in elderly patients is intriguing and of significant value in clinical applications. Senescent cells can accelerate tumor progression by metabolic reprogramming. Recent research has shown that methylmalonic acid (MMA) was significantly up-regulated in the serum of older individuals and played a central role in the development of aggressive characteristics. We found that the significant accumulation of MMA in elderly patients imparted proliferative potential to osteosarcoma cells. The expression of MAFB was excessively up-regulated in osteosarcoma specimens and was further enhanced in response to MMA accumulation as the patient aged. Specifically, we first confirmed a novel molecular mechanism between cellular senescence and cancer, in which the MMA-driven transcriptional reprogramming of the MAFB-NOTCH3 axis accelerated osteosarcoma progression via the activation of PI3K-AKT pathways. Moreover, the down-regulation of the MAFB-NOTCH3 axis increased the sensitivity and effect of AKT inhibitors in osteosarcoma through significant inhibition of AKT phosphorylation. In conclusion, we confirmed that MAFB is a novel age-dependent biomarker for osteosarcoma, and targeting the MAFB-NOTCH3 axis in combination with AKT inhibition can serve as a novel therapeutic strategy for elderly patients with osteosarcoma in experimental and clinical trials.

Decoding m6A mRNA methylation by reader proteins in liver diseases

N6-methyladenosine (m6A) is a dynamic and reversible epigenetic regulation. As the most prevalent internal post-transcriptional modification in eukaryotic RNA, it participates in the regulation of gene expression through various mechanisms, such as mRNA splicing, nuclear export, localization, translation efficiency, mRNA stability, and structural transformation. The involvement of m6A in the regulation of gene expression depends on the specific recognition of m6A-modified RNA by reader proteins. In the pathogenesis and treatment of liver disease, studies have found that the expression levels of key genes that promote or inhibit the development of liver disease are regulated by m6A modification, in which abnormal expression of reader proteins determines the fate of these gene transcripts. In this review, we introduce m6A readers, summarize the recognition and regulatory mechanisms of m6A readers on mRNA, and focus on the biological functions and mechanisms of m6A readers in liver cancer, viral hepatitis, non-alcoholic fatty liver disease (NAFLD), hepatic fibrosis (HF), acute liver injury (ALI), and other liver diseases. This information is expected to be of high value to researchers deciphering the links between m6A readers and human liver diseases.

Hippo-YAP/TAZ signaling in breast cancer: Reciprocal regulation of microRNAs and implications in precision medicine

Breast cancer is a molecularly heterogeneous disease and the most common female malignancy. In recent years, therapy approaches have evolved to accommodate molecular diversity, with a focus on more biologically based therapies to minimize negative consequences. To regulate cell fate in human breast cells, the Hippo signaling pathway has been associated with the alpha subtype of estrogen receptors. This pathway regulates tissue size, regeneration, and healing, as well as the survival of tissue-specific stem cells, proliferation, and apoptosis in a variety of organs, allowing for cell differentiation. Hippo signaling is mediated by the kinases MST1, MST2, LATS1, and LATS2, as well as the adaptor proteins SAV1 and MOB. These kinases phosphorylate the downstream effectors of the Hippo pathway, yes-associated protein (YAP), and transcriptional coactivator with PDZ-binding motif (TAZ), suppressing the expression of their downstream target genes. The Hippo signaling pathway kinase cascade plays a significant role in all cancers. Understanding the principles of this kinase cascade would prevent the occurrence of breast cancer. In recent years, small noncoding RNAs, or microRNAs, have been implicated in the development of several malignancies, including breast cancer. The interconnections between miRNAs and Hippo signaling pathway core proteins in the breast, on the other hand, remain poorly understood. In this review, we focused on highlighting the Hippo signaling system, its key parts, its importance in breast cancer, and its regulation by miRNAs and other related pathways.

RSPO2 as Wnt signaling enabler: Important roles in cancer development and therapeutic opportunities

R-spondins are secretory proteins localized in the endoplasmic reticulum and Golgi bodies and are processed through the secretory pathway. Among the R-spondin family, RSPO2 has emanated as a novel regulator of Wnt signaling, which has now been acknowledged in numerous in vitro and in vivo studies. Cancer is an abnormal growth of cells that proliferates and spreads uncontrollably due to the accumulation of genetic and epigenetic factors that constitutively activate Wnt signaling in various types of cancer. Colorectal cancer (CRC) begins when cells in the colon and rectum follow an indefinite pattern of division due to aberrant Wnt activation as one of the key hallmarks. Decades-long progress in research on R-spondins has demonstrated their oncogenic function in distinct cancer types, particularly CRC. As a critical regulator of the Wnt pathway, it modulates several phenotypes of cells, such as cell proliferation, invasion, migration, and cancer stem cell properties. Recently, RSPO mutations, gene rearrangements, fusions, copy number alterations, and altered gene expression have also been identified in a variety of cancers, including CRC. In this review, we addressed the recent updates regarding the recurrently altered R-spondins with special emphasis on the RSPO2 gene and its involvement in potentiating Wnt signaling in CRC. In addition to the compelling physiological and biological roles in cellular fate and regulation, we propose that RSPO2 would be valuable as a potential biomarker for prognostic, diagnostic, and therapeutic use in CRC.

Vault RNAs (vtRNAs): Rediscovered non-coding RNAs with diverse physiological and pathological activities

The physicochemical characteristics of RNA admit non-coding RNAs to perform a different range of biological acts through various mechanisms and are involved in regulating a diversity of fundamental processes. Notably, some reports of pathological conditions have proved abnormal expression of many non-coding RNAs guides the ailment. Vault RNAs are a class of non-coding RNAs containing stem regions or loops with well-conserved sequence patterns that play a fundamental role in the function of vault particles through RNA-ligand, RNA-RNA, or RNA-protein interactions. Taken together, vault RNAs have been proposed to be involved in a variety of functions such as cell proliferation, nucleocytoplasmic transport, intracellular detoxification processes, multidrug resistance, apoptosis, and autophagy, and serve as microRNA precursors and signaling pathways. Despite decades of investigations devoted, the biological function of the vault particle or the vault RNAs is not yet completely cleared. In this review, the current scientific assertions of the vital vault RNAs functions were discussed.

Crosstalk between glioblastoma and tumor microenvironment drives proneural-mesenchymal transition through ligand-receptor interactions

Glioblastoma (GBM) is the most common intrinsic and aggressive primary brain tumor in adults, with a median survival of approximately 15 months. GBM heterogeneity is considered responsible for the treatment resistance and unfavorable prognosis. Proneural-mesenchymal transition (PMT) represents GBM malignant progression and recurrence, which might be a breakthrough to understand GBM heterogeneity and overcome treatment resistance. PMT is a complicated process influenced by crosstalk between GBM and tumor microenvironment, depending on intricate ligand-receptor interactions. In this review, we summarize the autocrine and paracrine pathways in the GBM microenvironment and related ligand-receptor interactions inducing PMT. We also discuss the current therapies targeting the PMT-related autocrine and paracrine pathways. Together, this review offers a comprehensive understanding of the failure of GBM-targeted therapy and ideas for future tendencies of GBM treatment.

Loss of GATA6-mediated up-regulation of UTX promotes pancreatic tumorigenesis and progression

Ubiquitously transcribed tetratricopeptide repeat on chromosome X (UTX), also known as lysine (K)-specific demethylase 6A (KDM6A), functions as a tumor suppressor gene or oncogene depending on the tumor type and context. However, its tumor-suppressive mechanisms remain largely unknown. Here, we investigated the clinical significance and biological effects of UTX expression in pancreatic ductal adenocarcinoma (PDA) and determined the potential mechanisms of its dysregulation. UTX expression and its association with clinicopathologic characteristics of PDA patients were analyzed using immunohistochemistry. UTX mRNA and protein expression and their regulation in PDA cell lines were measured using quantitative polymerase chain reaction and Western blot analyses. The biological functions of UTX in PDA cell growth, migration, and invasion were determined using gain- and loss-of-function assays with both in vitro and in vivo animal models. UTX expression was reduced in human PDA cell lines and specimens. Low UTX expression was associated with poor differentiation and prognosis in PDA. Forced UTX expression inhibited PDA proliferation, migration, and invasion in vitro and PDA growth and metastasis in vivo, whereas knockdown of UTX expression did the opposite. Mechanistically, UTX expression was trans-activated by GATA6 activation. GATA6-mediated PDA progression could be blocked, at least partially, by silencing UTX expression. In conclusion, loss of GATA6-mediated UTX expression was evident in human PDA and restored UTX expression suppressed PDA growth and metastasis. Thus, UTX is a tumor suppressor in PDA and may serve as a prognostic biomarker and therapeutic target.

Oncogenic MORC2 in cancer development and beyond

Microrchidia CW-type zinc finger 2 (MORC2) is a member of the MORC superfamily of nuclear proteins. Growing evidence has shown that MORC2 not only participates in gene transcription and chromatin remodeling but also plays a key in human disease and tumor development by regulating the expression of downstream oncogenes or tumor suppressors. The present review provides an updated overview of MORC2 in the aspect of cancer hallmark and therapeutic resistance and summarizes its upstream regulators and downstream target genes. This systematic review may provide a favorable theoretical basis for emerging players of MORC2 in tumor development and new insight into the potential clinical application of basic science discoveries in the future.

Physiological and pathological functions of circular RNAs in the nervous system

Circular RNAs (circRNAs) are a class of covalently closed single-stranded RNAs that are expressed during the development of specific cells and tissues. CircRNAs play crucial roles in physiological and pathological processes by sponging microRNAs, modulating gene transcription, controlling the activity of certain RNA-binding proteins, and producing functional peptides. A key focus of research at present is the functionality of circRNAs in the nervous system and several advances have emerged over the last 2 years. However, the precise role of circRNAs in the nervous system has yet to be comprehensively reviewed. In this review, we first summarize the recently described roles of circRNAs in brain development, maturity, and aging. Then, we focus on the involvement of circRNAs in various diseases of the central nervous system, such as brain cancer, chronic neurodegenerative diseases, acute injuries of the nervous system, and neuropathic pain. A better understanding of the functionality of circRNAs will help us to develop potential diagnostic, prognostic, and therapeutic strategies to treat diseases of the nervous system.

Jingfang granule alleviates Pseudomonas aeruginosa-induced acute lung inflammation through suppression of STAT3/IL-17/NF-κB pathway based on network pharmacology analysis and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Pseudomonas aeruginosa is an opportunistic bacterial pathogen which is the second leading cause of hospital-acquired pneumonia. Jingfang granule (JFG) is an herbal formula of Traditional Chinese medicine (TCM) widely used in treatment of acute respiratory tract infections in China. However, the molecular mechanisms of JFG in treatment of P. aeruginosa-induced acute pneumonia are not clear.

AIM OF STUDY

This study aimed to investigate the mechanisms underlying the effects of JFG on P. aeruginosa-induced acute inflammation using a mouse model of bacterial acute pneumonia.

MATERIALS AND METHODS

The chemical components and targets of JFG were retrieved from Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, and the P. aeruginosa pneumonia-related targets were obtained from the disease databases, including Online Mendelian Inheritance in Man (OMIM), GeneCards and DisGeNet. The protein-protein interaction (PPI) network was constructed using STRING database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID). Molecular docking was performed using AutoDockTools 1.5.6. Further in vivo experiments employed a mouse model of P. aeruginosa acute pneumonia to verify the target proteins and signaling pathways affected by JFG, which were predicted by the network pharmacology analysis.

RESULTS

A total of 218 active components and 257 targets of JFG were retrieved from TCMSP database. Moreover, 99 intersectant targets were obtained between the 257 JFG targets and 694 disease targets. Among the intersectant targets, STAT3, IL-6, AKT1, TNF, MAPK1, MAPK3 and EGFR were identified to be the key therapeutic targets through PPI network analysis, and STAT3 was in the center of the network, which is a key regulator of IL-17 expression. KEGG pathway enrichment analysis suggested that IL-17 signaling pathway was one of the crucial inflammatory pathways affected by JFG in treatment of P. aeruginosa pneumonia. Furthermore, the in vivo experiments demonstrated that the JFG-treated mice displayed reduced proinflammatory cytokine production (IL-17, IL-1β, IL-6 and TNF), diminished neutrophil infiltration and decreased mortality, compared with the non-drug-treated mice during P. aeruginosa lung infection. Moreover, the expression or phosphorylation levels of the key regulators in STAT3/IL-17/NF-κB axis including STAT3, ERK1/2 (MAPK3/1), AKT, NF-κB p65 and RORγt were significantly reduced in the lung tissues of the JFG-treated mice.

CONCLUSION

JFG was effective in treatment of P. aeruginosa acute lung infection, which reduced inflammatory responses through suppressing STAT3/IL-17/NF-κB pathway.

Sijunzi decoction ameliorates gastric precancerous lesions via regulating oxidative phosphorylation based on proteomics and metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Sijunzi decoction (SJZD), a traditional Chinese medicine formula, is commonly used in clinical practice for the treatment of gastric precancerous lesions (GPL). However, the mechanism of gastric protection is not fully understood.

AIMS OF THE STUDY

The purpose of this study was to systematically evaluate the efficacy of SJZD in blocking the development of GPL and to reveal the underlying mechanism.

METHODS

First, we established a rat model of GPL, which was induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) combined with an irregular diet and 40% ethanol. The efficacy of SJZD was evaluated based on pathological sections and serum biochemical indices. Then, the pharmacodynamic mechanism of SJZD was revealed by quantitative proteomics based on stable isotope dimethyl labeling. At the same time, the pharmacodynamic mechanism was verified by quantitative metabolomics. In addition, the anti-gastritis effect of SJZD was confirmed by a serum pharmacology method in a cell model, and the functional mechanism was further verified.

RESULTS

We demonstrated that SJZD could block the development of GPL in the animal model. Proteomics and metabolomics revealed that SJZD blocks GPL development by regulating oxidative phosphorylation (OXPHOS). In addition, the serum pharmacology results showed that SJZD-containing serum (SJZD-CS) could inhibit apoptosis in MNNG-induced GES-1 cells. OXPHOS inhibitors could significantly reduce the protective effect of SJZD-CS.

CONCLUSION

SJZD effectively ameliorates GPL, and proteomics and metabolomics revealed that its protective effects are closely related to OXPHOS.

Wei-fu-chun tablet halted gastric intestinal metaplasia and dysplasia associated with inflammation by regulating the NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Chi006Eese herbal medicine Weifuchun Tablets (WFC) approved by the State Food and Drug Administration in 1982 has been widely used in treating a variety of chronic stomach disorders including Chronic atrophic gastritis (CAG) and Gastric precancerous lesions in China clinically. This study aimed to investigate the efficacy and potential mechanism of WFC in treating Gastric intestinal metaplasia (GIM) and Gastric dysplasia (GDys).

MATERIALS AND METHODS

Rat GIM and GDys established by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) combined with hot paste, ethanol injury, and intermittent fasting were intervened by WFC. Body weight, histopathology, pH of gastric acid, pepsin activity, intestinal metaplasia index and inflammation were detected. Rat bone marrow derived macrophages (BMDMs) pretreated with WFC were stimulated by LPS. Inflammatory factors and the nuclear factor-kappa B (NF-κB) pathway were assessed. GES-1 cells pretreated by WFC were stimulated by MNNG and TNF-α, intestinal metaplasia index, the NF-κB pathway and interaction between P65 and CDX2 were detected.

RESULTS

WFC improved rat body weight, histopathology, pH value of gastric acid, activity of gastric pepsin, intestinal metaplasia (CDX2), inflammation (IL-1β, IL-6 and TNF-α), macrophage aggregation (CD68) in gastric mucosa in rat GIM and GDys. WFC inhibited inflammation (IL-1β and TNF-α) by inactivating the NF-κB pathway. WFC reduced the expression of CDX2 by inhibiting the binding of CDX2 promoter TSS upstream region with p65.

CONCLUSION

WFC blocked GIM and GDys associated with inflammation by regulating the NF-κB pathway.

Sargentodoxa cuneata and Patrinia villosa extract inhibits LPS-induced inflammation by shifting macrophages polarization through FAK/PI3K/Akt pathway regulation and glucose metabolism reprogramming

ETHNOPHARMACOLOGICAL RELEVANCE

Sargentodoxa cuneata and Patrinia villosa (S&P) are two natural herbal medicine widely used for treatment of various inflammatory diseases in Traditional Chinese Medicine, whereas the mode of action needs to be further investigated.

AIM OF THE STUDY

This study aimed to explore the anti-inflammatory effects and unravel the involved mechanism of S&P extract.

MATERIALS AND METHODS

The components of S&P extract were first detected using the liquid chromatography-tandem mass spectrometry (LC-MS/MS). The effects of S&P extract on the viability and migration ability of macrophages were detected using CCK8, LDH, adhesion and transwell assays. Cytokine release and macrophage phenotype transition were measured using a cytometric bead array and flow cytometry. The potential mechanism was uncovered using an integrative approach combining RNA sequencing and LC-MS/MS-based metabolic analysis. The expression of related proteins was further validated using western blotting.

RESULTS

S&P extract inhibited the proliferation and migration of LPS-induced macrophages, changed the morphology of macrophages, and inhibited the production of NO and the expression of iNOS. Furthermore, the extract inhibited tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production and the expression of the M1 phenotype markers CD11c and CD16/32, whereas it promoted interleukin-10 (IL-10) production and the expression of the M2 phenotype markers CD206 and arginase 1 (Arg1). RNA sequencing analysis demonstrated that the upregulated genes by S&P extract treatment were involved in M2 macrophages: Il10, Ccl17, Ccl22, Cd68. The downregulated genes were involved in M1 macrophages and glycolysis processes: Stat1, Il18, Cd80, Cd86, Nos2, Il6, Pik3ap1, Raf1, Pdhb, etc. Metabolomics results showed that the S&P extract strongly ameliorated lipopolysaccharide (LPS)-induced metabolic disturbances. KEGG analysis indicated that most of these metabolites were involved in glucose metabolism, which is involved in the tumor necrosis factor (TNF), phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt), Glycolysis, and mitogen-activated protein kinase (MAPK) pathways. In vitro experiments further confirmed that the extract significantly inhibited the phosphorylation of focal adhesion kinase (FAK), PI3K and Akt, and the expression of glucose metabolism-related proteins. Adding a FAK inhibitor (defactinib) further inhibited the expression of M1/M2 phenotypic markers and the phosphorylation of FAK, PI3K, and Akt.

CONCLUSIONS

S&P extract can induce M2 polarization and shift macrophages from M1 to M2 tissue repair in LPS-induced inflammation by regulating glucose metabolism and the FAK/PI3K/Akt pathway.