The Wnt/β-catenin pathway cross-talks with STAT3 signaling to regulate survival of retinal pigment epithelium cells

Protective potential of nodakenin in high-fat diet-mediated colitis-associated cancer: Inhibition of STAT3 activation and Wnt/β-catenin pathway, and gut microbiota modulation

A high-fat diet (HFD) exerts complex effects on the risk of colitis-associated cancer (CAC). Nodakenin, a key phytochemical isolated from the dried roots of Angelicae gigas Nakai (Umbelliferae), possesses anti-inflammatory and anti-adipogenic properties and shows potential as a therapeutic agent for colorectal cancer (CRC). In this study, we investigated the protective effects and underlying molecular mechanisms of nodakenin in an animal model of CRC induced by HFD, azoxymethane (AOM), and dextran sodium sulfate (DSS). Oral administration of nodakenin significantly alleviated clinical symptoms, such as recovery of weight, spleen weight, and colon length, and suppressed tumor progression in the colonic tissues of HFD/AOM/DSS-induced CRC mice. Nodakenin inhibited the activation of STAT3-related inflammatory mediators and downregulated proteins involved in the Wnt/β-catenin signaling pathway. These effects contributed to the disruption of epithelial-mesenchymal transition (EMT) and the restoration of tight junction integrity within the colonic tissue. Furthermore, nodakenin treatment improved the composition of the gut microbiota, leading to observable species-level differences. Network analysis revealed significant correlations between clinical parameters, inflammatory markers, EMT and apoptotic factors, and the composition of the gut microbiota. Specifically, negative correlations were observed between spleen weight and Alistipes, as well as between MCP-1 and Clostridium_g21. Positive correlations with spleen weight were observed with species belonging to Anaerotruncus, Emergencia, and Parvibacter. Bacteroidaceae_uc and Bacteroides correlated positively with MCP-1, Streptococcus correlated positively with PUMA, and Harryflintia, Odoribacteraceae_uc, and Roseburia correlated positively with cleaved caspase-3. Overall, our findings suggested that nodakenin effectively alleviates HFD/AOM/DSS-induced CRC by targeting inflammatory pathways (STAT3 and Wnt/β-catenin), suppressing EMT, and restoring gut microbiota balance. These multiple mechanisms underscore its potential as a promising agent for the prevention and treatment of colitis-associated colorectal cancer.

Identification of telomere maintenance-driven molecular subtypes in hepatocellular carcinoma: implications for prognosis and targeted therapy via KPNA2

BACKGROUND

Telomere maintenance (TM) plays a pivotal role in regulating the pathogenesis of hepatocellular carcinoma (HCC) and is crucial for defining the clinical characteristics of patients. Despite previous publications highlighting the correlation between individual TM-related genes and HCC, comprehensive exploration and systematic analysis of these genes are still lacking.

METHODS

Through the analysis of transcriptome data, we identified two distinct clusters (termed telomere maintenance-associated clusters, or TCs) that exhibited marked heterogeneity in clinical traits and the tumor microenvironment. Following this, we conducted an exhaustive screening process to select 15 prognostic genes related to telomere maintenance and developed corresponding TM scores for these genes. Additionally, we rigorously validated the expression and oncogenic functions of karyopherin subunit alpha 2 (KPNA2) in both HCC tissues and cell lines.

RESULTS

TC1 demonstrated a significant correlation with cellular differentiation and the fatty acid metabolism pathway, while also predicting a low tumor mutation burden (TMB) alongside favorable prognostic outcomes. In contrast, TC2 was intricately linked to TM, cell cycle regulation, and DNA repair. When examining the relationship between TMB and overall survival rates. Notably, substantial heterogeneity was observed among the various TCs. Furthermore, KPNA2 exhibited upregulation and has the potential to enhance HCC proliferation and migration.

CONCLUSION

In summary, through the integration of bioinformatics and functional experimentation, we have delineated two distinct molecular classifications predicated on their association with TM-related genes in HCC. This groundbreaking discovery holds the potential to introduce innovative concepts and novel biomarkers into clinical practice.

Ferroptosis enhances the therapeutic potential of oncolytic adenoviruses KD01 against cancer

Oncolytic virotherapy has emerged as a promising strategy for cancer treatment by selectively targeting and lysing tumor cells. However, its efficacy is often limited in certain tumor types due to multiple factors. This study explores the combination of oncolytic adenoviruses with Erastin, a potent ferroptosis inducer, to enhance antitumor efficacy in oncolytic virus-insensitive cancer cell lines. In vitro experiments demonstrated that Erastin significantly increased the cytotoxicity of oncolytic virotherapy, leading to greater inhibition of cell proliferation and elevated rates of cell death compared to monotherapies. The combination treatment further promoted ferroptosis, as evidenced by increased reactive oxygen species (ROS) levels, enhanced lipid peroxidation, and disrupted redox homeostasis. RNA sequencing identified the downregulation of Dickkopf-1 (DKK1) as a key mediator of the enhanced ferroptotic effect. Restoring the expression of DKK1 partially mitigated the cytotoxic effects of the combination therapy, highlighting its crucial role in mediating the enhanced ferroptosis-induced oncolytic virotherapy efficacy. In vivo studies further validated these findings, demonstrating that the combined treatment significantly reduced tumor growth without inducing notable toxicity. This novel therapeutic approach has great potential to enhance the efficacy of oncolytic virotherapy in cancers resistant to oncolytic viruses by inducing ferroptosis. Further investigation in clinically relevant models is warranted to fully elucidate the underlying mechanisms and to optimize this combination strategy for potential clinical applications.

The molecular mechanisms underlying retinal ganglion cell apoptosis and optic nerve regeneration in glaucoma (Review)

Glaucoma is a neurodegenerative disease characterized by progressive and irreversible necrosis and apoptosis of retinal ganglion cells (RGCs). Deformation of the lamina cribrosa (LC) has been identified as a factor leading to damage to the optic nerve and capillaries passing through the LC, ultimately causing visual field defects and glaucoma development. Recent advancements in molecular biology, both domestically and internationally, have enabled a more comprehensive and in‑depth understanding of glaucoma pathogenesis. In the present review, the role of molecular signaling pathways associated with RGCs apoptosis, optic nerve protection and regeneration, and LC damage and remodeling in the development of glaucoma, are summarized and discussed. The insights provided herein may offer new targets and ideas for interventions and treatment strategies for glaucoma.

Direct reprogramming of human fibroblasts into hair-inducing dermal papilla cell-like cells by a single small molecule

Dermal papilla cells (DPCs) are a crucial subset of mesenchymal cells in the skin responsible for regulating hair follicle development and growth, making them invaluable for cell-based therapies targeting hair loss. However, obtaining sufficient DPCs with potent hair-inducing abilities remains a persistent challenge. In this study, the Food and Drug Administration (FDA)-approved drug library was utilized to screen small molecules capable of reprogramming readily accessible human skin fibroblasts into functional DPCs. In the initial screening, five candidate small molecules were identified from a pool of 1,817 compounds, and the small molecule peficitinib was further identified by the further hair follicle regeneration experiments. Following peficitinib treatment, fibroblasts derived from primary human foreskin and scalp exhibited the capability to induce hair growth and possessed a molecular profile highly similar to that of primary DPCs. We refer to these cells as dermal papilla cell-like cells (DPC-LCs). Furthermore, transcriptome analysis showed that the wingless/integrated (Wnt) signaling pathway and the transforming growth factor β (TGF-β) signaling pathway, both of which play crucial roles in hair follicle morphogenesis, are upregulated and enriched in these DPC-LCs. These functional DPC-LCs offer a promising avenue for obtaining a plentiful supply of hair-inducing cells, thereby advancing the development of therapeutic strategies for hair loss treatment.

Wnt-Activated Immunoregulatory Myeloid Cells Prevent Relapse in Experimental Autoimmune Encephalomyelitis and Offer a Potential Therapeutic Strategy for Multiple Sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by recurrent inflammatory relapses and neurodegeneration. Myeloid cells play a critical role in shaping the inflammatory environment and influencing disease progression. Here, we demonstrate that activation of the Wnt signaling pathway reprograms myeloid cells into an immunoregulatory phenotype, leading to reduced neuroinflammation and disease severity. Using both experimental autoimmune encephalomyelitis (EAE) and human-derived myeloid cells, we show that Wnt agonist treatment promotes the expression of inhibitory molecules such as PD-L1 and PD-L2, suppressing pro-inflammatory responses. In the chronic and relapsing-remitting EAE models, Wnt activation significantly reduced disease severity, immune cell infiltration into the CNS, and pathogenic T cell responses. Notably, in relapsing-remitting EAE, Wnt treatment prevented new relapses in a PD-L1-dependent manner, highlighting the crucial role of myeloid cell-mediated immune regulation. These findings reveal a previously unrecognized role for Wnt signaling in myeloid cell immunoregulation and suggest that targeting this pathway could provide a novel therapeutic strategy for MS and other autoimmune diseases.

pSTAT3 activation of Foxl2 initiates the female pathway underlying temperature-dependent sex determination

Ovarian development was traditionally recognized as a "default" sexual outcome and therefore received much less scientific attention than testis development. In turtles with temperature-dependent sex determination (TSD), how the female pathway is initiated to induce ovary development remains unknown. In this study, we have found that phosphorylation of the signal transducer and activator of transcription 3 (pSTAT3) and Foxl2 exhibit temperature-dependent sexually dimorphic patterns and tempo-spatial coexpression in early embryos of the red-eared slider turtle (Trachemys scripta elegans). Inhibition of pSTAT3 at a female-producing temperature of 31 °C induces 64.7% female-to-male sex reversal, whereas activation of pSTAT3 at a male-producing temperature of 26 °C triggers 75.6% male-to-female sex reversal. In addition, pSTAT3 directly binds to the locus of the female sex-determining gene Foxl2 and promotes Foxl2 transcription. Overexpression or knockdown of Foxl2 can rescue the sex reversal induced by inhibition or activation of pSTAT3. This study has established a direct genetic link between warm temperature-induced STAT3 phosphorylation and female pathway initiation in a TSD system, highlighting the critical role of pSTAT3 in the cross talk between female and male pathways.

Single-cell transcriptomics reveals the intra-tumoral heterogeneity and SQSTM1/P62 and Wnt/β-catenin mediated epithelial to mesenchymal transition and stemness of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is characterized by the complex tumor microenvironment (TME) consisting of an abundance of mesenchymal stem cells (MSCs), which is known to facilitate epithelial-to-mesenchymal transition (EMT). The development of single-cell genomics is a powerful method for defining the intricate genetic landscapes of malignancies. In this study, we have employed single-cell RNA sequencing (scRNA-seq) to dissect the intra-tumoral heterogeneity and analyze the single-cell transcriptomic landscape to detect rare consequential cell subpopulations of significance. The scRNA-seq analysis of TNBC and Normal patient derived samples revealed that EMT markers and transcription factors were most upregulated in MSC population. Further, exploration of gene expression analysis among TNBC and Normal patient-derived MSCs ascertained the role of SQSTM1/P62 and Wnt/β-catenin in TNBC progression. Wnt/β-catenin and Wnt/PCP signaling pathways are prominent contributors of EMT, stemness, and cancer stem cell (CSC) properties of TNBC. SQSTM1/P62 cooperates with the components of the Wnt/PCP signaling pathway and is critically involved at the interface of autophagy and EMT. Moreover, siRNA targeting SQSTM1/P62 and inhibitor of Wnt/β-catenin (FH535) in conjunction was used to explore molecular modification of EMT and stemness markers. Although SQSTM1/P62 is not crucial for cell survival, cytotoxicity assay revealed synergistic interaction between the siRNA/inhibitor. Modulation of these important pathways helped in reduction of expression of genes and proteins contributing to CSC properties. Gene and protein expression analysis revealed the induction of EMT to MET. Moreover, co-treatment resulted in inactivation of non-canonical Wnt VANGL2-JNK signaling axis. The synergistic impact of inhibition of SQSTM1/P62 and Wnt/β-catenin signaling facilitates the development of a potential therapeutic regimen for TNBC.

Nifuroxazide repurposing for protection from diabetes-induced retinal injury in rats: Implication of oxidative stress and JAK/STAT3 axis

The prevalence of diabetes mellitus (DM) is alarmingly increasing worldwide. Diabetic retinopathy (DR) is a prevailing DM microvascular complication, representing the major cause of blindness in working-age population. Inflammation is a crucial player in DR pathogenesis. JAK/STAT3 axis is a pleotropic cascade that modulates diverse inflammatory events. Nifuroxazide (Nifu) is a commonly used oral antibiotic with reported JAK/STAT3 inhibition activity. The present study investigated the potential protective effect of Nifu against diabetes-induced retinal injury. Effect of Nifu on oxidative stress, JAK/STAT3 axis and downstream inflammatory mediators has been also studied. Diabetes was induced in Sprague Dawley rats by single intraperitoneal injection of streptozotocin (50 mg/kg). Animals were assigned into four groups: normal, Nifu control, DM, and DM + Nifu. Nifu was orally administrated at 25 mg/kg/day for 8 weeks. The effects of Nifu on oxidative stress, JAK/STAT3 axis proteins, inflammatory factors, tight junction proteins, histological, and ultrastructural alterations were evaluated using spectrophotometry, gene and protein analyses, and histological studies. Nifu administration to diabetic rats attenuated histopathological and signs of retinal injury. Additionally, Nifu attenuated retinal oxidative stress, inhibited JAK and STAT3 phosphorylation, augmented the expression of STAT3 signaling inhibitor SOCS3, dampened the expression of transcription factor of inflammation NF-κB, and inflammatory cytokine TNF-α. Collectively, the current study indicated that Nifu alleviated DR progression in diabetic rats, suggesting beneficial retino-protective effect. This can be attributed to blocking JAK/STAT3 axis in retinal tissues with subsequent amelioration of oxidative stress and inflammation.

LncRNA-CCAT5-mediated crosstalk between Wnt/β-Catenin and STAT3 signaling suggests novel therapeutic approaches for metastatic gastric cancer with high Wnt activity

BACKGROUND

Although the constitutively activated Wnt/β-catenin signaling pathway plays vital roles in gastric cancer (GC) progression, few Wnt inhibitors are approved for clinical use. Additionally, the clinical significance of long non-coding RNAs (lncRNAs) in GC intraperitoneal dissemination (IPD) remains elusive. Here, we investigated the function and therapeutic potential of Wnt-transactivated lncRNA, colon cancer-associated transcript 5 (CCAT5), in GC metastasis.

METHODS

LncRNA-sequencing assay was performed to document abundance changes of lncRNAs induced by Wnt family member 3A (Wnt3a) and degradation-resistant β-catenin (S33Y mutated) in ascites-derived GC cells with low Wnt activity. Luciferase reporter, Chromatin immunoprecipitation (ChIP)-re-ChIP assays were performed to determine how CCAT5 was transcribed. The clinical significance of CCAT5 was examined in 2 cohorts of GC patients. The biological function of CCAT5 was investigated through gain- and loss-of-function studies. The molecular mechanism was explored through RNA-sequencing, mass spectrometry, and CRISPR/Cas9-knocknout system. The therapeutic potential of CCAT5 was examined through RNAi-based cell xenograft model and patient-derived xenograft (PDX) model of IPD.

RESULTS

We identified a novel Wnt-regulated lncRNA, CCAT5, which was transactivated by the β-catenin/transcription factor 3 (TCF3) complex. CCAT5 was significantly upregulated in GC and predicted poor prognosis. Functional studies confirmed the promotive role of CCAT5 in GC growth and metastasis. Mechanistically, CCAT5 bound to the C-end domain of signal transducer and activator of transcription 3 (STAT3) and blocks Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1)-mediated STAT3Y705 dephosphorylation, leading to STAT3 nuclear entry and transactivation, thus accelerating GC progression. Furthermore, we demonstrated that both Wnt3a and β-catenin acted as activator of STAT3 signaling pathway, and the interplay between CCAT5 and STAT3 was functionally essential for Wnt-drived STAT3 signaling and tumor evolution. Finally, we revealed in vivo si-CCAT5 selectively attenuated growth and metastasis of Wnthigh GC, but not Wntlow GC. The combination of si-CCAT5 and oxaliplatin displayed obvious synergistic therapeutic effects on Wnthigh PDX mice.

CONCLUSIONS

We identified a novel Wnt-transactivated lncRNA, CCAT5. Our study revealed a mechanism of STAT3 signaling regulation via canonical Wnt signaling and the functional significance of CCAT5 as critical mediator. We provided conceptual advance that lncRNAs serve as therapeutic targets reversing GC progression.

Distinct mouse models of Stargardt disease display differences in pharmacological targeting of ceramides and inflammatory responses

Mutations in many visual cycle enzymes in photoreceptors and retinal pigment epithelium (RPE) cells can lead to the chronic accumulation of toxic retinoid byproducts, which poison photoreceptors and the underlying RPE if left unchecked. Without a functional ATP-binding cassette, sub-family A, member 4 (ABCA4), there is an elevation of all-trans-retinal and prolonged buildup of all-trans-retinal adducts, resulting in a retinal degenerative disease known as Stargardt-1 disease. Even in this monogenic disorder, there is significant heterogeneity in the time to onset of symptoms among patients. Using a combination of molecular techniques, we studied Abca4 knockout (simulating human noncoding disease variants) and Abca4 knock-in mice (simulating human misfolded, catalytically inactive protein variants), which serve as models for Stargardt-1 disease. We compared the two strains to ascertain whether they exhibit differential responses to agents that affect cytokine signaling and/or ceramide metabolism, as alterations in either of these pathways can exacerbate retinal degenerative phenotypes. We found different degrees of responsiveness to maraviroc, a known immunomodulatory CCR5 antagonist, and to the ceramide-lowering agent AdipoRon, an agonist of the ADIPOR1 and ADIPOR2 receptors. The two strains also display different degrees of transcriptional deviation from matched WT controls. Our phenotypic comparison of the two distinct Abca4 mutant-mouse models sheds light on potential therapeutic avenues previously unexplored in the treatment of Stargardt disease and provides a surrogate assay for assessing the effectiveness for genome editing.

RhoA Promotes Synovial Proliferation and Bone Erosion in Rheumatoid Arthritis through Wnt/PCP Pathway

Ras homolog gene family member A (RhoA) plays a major role in the Wnt/planar cell polarity (PCP) pathway, which is significantly activated in patients with rheumatoid arthritis (RA). The function of RhoA in RA synovitis and bone erosion is still elusive. Here, we not only explored the impact of RhoA on the proliferation and invasion of RA fibroblast-like synoviocytes (FLSs) but also elucidated its effect on mouse osteoclast and a mouse model of collagen-induced arthritis (CIA). Results showed that RhoA was overexpressed in RA and CIA synovial tissues. Lentivirus-mediated silencing of RhoA increased apoptosis, attenuated invasion, and dramatically upregulated osteoprotegerin/receptor activator of nuclear factor-κB ligand (OPG/RANKL) ratio in RA-FLSs. Additionally, the silencing of RhoA inhibited mouse osteoclast differentiation in vitro and alleviated synovial hyperplasia and bone erosion in the CIA mouse model. These effects in RA-FLSs and osteoclasts were all regulated by RhoA/Rho-associated protein kinase 2 (ROCK2) and might interact with Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways.

NLRP12 downregulates the Wnt/β-catenin pathway via interaction with STK38 to suppress colorectal cancer

Colorectal cancer (CRC) at advanced stages is rarely curable, underscoring the importance of exploring the mechanism of CRC progression and invasion. NOD-like receptor family member NLRP12 was shown to suppress colorectal tumorigenesis, but the precise mechanism was unknown. Here, we demonstrate that invasive adenocarcinoma development in Nlrp12-deficient mice is associated with elevated expression of genes involved in proliferation, matrix degradation, and epithelial-mesenchymal transition. Signaling pathway analysis revealed higher activation of the Wnt/β-catenin pathway, but not NF-κB and MAPK pathways, in the Nlrp12-deficient tumors. Using Nlrp12-conditional knockout mice, we revealed that NLRP12 downregulates β-catenin activation in intestinal epithelial cells, thereby suppressing colorectal tumorigenesis. Consistent with this, Nlrp12-deficient intestinal organoids and CRC cells showed increased proliferation, accompanied by higher activation of β-catenin in vitro. With proteomic studies, we identified STK38 as an interacting partner of NLRP12 involved in the inhibition of phosphorylation of GSK3β, leading to the degradation of β-catenin. Consistently, the expression of NLRP12 was significantly reduced, while p-GSK3β and β-catenin were upregulated in mouse and human colorectal tumor tissues. In summary, NLRP12 is a potent negative regulator of the Wnt/β-catenin pathway, and the NLRP12/STK38/GSK3β signaling axis could be a promising therapeutic target for CRC.

Blockade of the SRC/STAT3/BCL-2 Signaling Axis Sustains the Cytotoxicity in Human Colorectal Cancer Cell Lines Induced by Dehydroxyhispolon Methyl Ether

Colorectal cancer (CRC) is the third most prevalent human cancer globally. 5-Fluorouracil (5-FU)-based systemic chemotherapy is the primary strategy for advanced CRC treatment, yet is limited by poor response rate. Deregulated activation of signal transducer and activator of transcription 3 (STAT3) is fundamental to driving CRC malignant transformation and a poor prognostic marker for CRC, underscoring STAT3 as a promising CRC drug target. Dehydroxyhispolon methyl ether (DHME) is an analog of Hispolon, an anticancer polyphenol abundant in the medicinal mushroom Phellinus linteus. Previously, we have established DHME's cytotoxic effect on human CRC cell lines by eliciting apoptosis through the blockade of WNT/β-catenin signaling, a preeminent CRC oncogenic pathway. Herein, we unraveled that compared with 5-FU, DHME is a more potent killer of CRC cells while being much less toxic to normal colon epithelial cells. DHME suppressed both constitutive and interleukin 6 (IL-6)-induced STAT3 activation represented by tyrosine 705 phosphorylation of STAT3 (p-STAT3 (Y705)); notably, DHME-induced CRC apoptosis and clonogenicity limitation were abrogated by ectopic expression of STAT3-C, a dominant-active STAT3 mutant. Additionally, we proved that BCL-2 downregulation caused by DHME-mediated STAT3 blockage is responsible for DHME-induced CRC cell apoptosis. Lastly, DHME inhibited SRC activation, and v-src overexpression restored p-STAT3 (Y705) levels along with lowering the levels of apoptosis in DHME-treated CRC cells. We conclude DHME provokes CRC cell apoptosis by blocking the SRC/STAT3/BCL-2 axis besides thwarting WNT/β-catenin signaling. The notion that DHME targets two fundamental CRC signaling pathways underpins the potential of DHME as a CRC chemotherapy agent.

Epigenetic upregulation of Schlafen11 renders WNT- and SHH-activated medulloblastomas sensitive to cisplatin

BACKGROUND

Intensive chemotherapeutic regimens with craniospinal irradiation have greatly improved survival in medulloblastoma patients. However, survival markedly differs among molecular subgroups and their biomarkers are unknown. Through unbiased screening, we found Schlafen family member 11 (SLFN11), which is known to improve response to DNA damaging agents in various cancers, to be one of the top prognostic markers in medulloblastomas. Hence, we explored the expression and functions of SLFN11 in medulloblastoma.

METHODS

SLFN11 expression for each subgroup was assessed by immunohistochemistry in 98 medulloblastoma patient samples and by analyzing transcriptomic databases. We genetically or epigenetically modulated SLFN11 expression in medulloblastoma cell lines and determined cytotoxic response to the DNA damaging agents cisplatin and topoisomerase I inhibitor SN-38 in vitro and in vivo.

RESULTS

High SLFN11 expressing cases exhibited significantly longer survival than low expressing cases. SLFN11 was highly expressed in the WNT-activated subgroup and in a proportion of the SHH-activated subgroup. While WNT activation was not a direct cause of the high expression of SLFN11, a specific hypomethylation locus on the SLFN11 promoter was significantly correlated with high SLFN11 expression. Overexpression or deletion of SLFN11 made medulloblastoma cells sensitive and resistant to cisplatin and SN-38, respectively. Pharmacological upregulation of SLFN11 by the brain-penetrant histone deacetylase-inhibitor RG2833 markedly increased sensitivity to cisplatin and SN-38 in SLFN11-negative medulloblastoma cells. Intracranial xenograft studies also showed marked sensitivity to cisplatin by SLFN11-overexpression in medulloblastoma cells.

CONCLUSIONS

High SLFN11 expression is one factor which renders favorable outcomes in WNT-activated and a subset of SHH-activated medulloblastoma possibly through enhancing response to cisplatin.

Loss of Stat3 in Osterix+ cells impairs dental hard tissues development

BACKGROUND

Mutations in the signal transducers and activators of transcription 3 (STAT3) gene result in hyper-IgE syndrome(HIES), a rare immunodeficiency that causes abnormalities in immune system, bones and teeth. However, the role of Stat3 in development of dental hard tissues was yet to investigate.

METHODS

In this study, a transgenic mouse of conditional knockout of Stat3 in dental mesenchymal cells (Osx-Cre; Stat3^fl/fl, Stat3 CKO) was made. The differences of postnatal tooth development between control and Stat3 CKO mice were compared by histology, µCT and scanning electron microscopy.

RESULT

Compared with the control, Stat3 CKO mice were presented with remarkable abnormal tooth phenotypes characterized by short root and thin dentin in molars and incisors. The enamel defects were also found on mandibular incisors. showed that Ki67-positive cells significantly decreased in dental mesenchymal of Stat3 CKO mice. In addition, β-catenin signaling was reduced in Hertwig's epithelial root sheath (HERS) and odontoblasts of Stat3 CKO mice.

CONCLUSIONS

Our results suggested that Stat3 played an important role in dental hard tissues development, and Stat3 may regulate dentin and tooth root development through the β-catenin signaling pathway.

Recent progress in ferroptosis: inducers and inhibitors

Ferroptosis is a new iron-dependent form of programmed cell death characterized by iron accumulation and lipid peroxidation. In recent years, ferroptosis has garnered enormous interest in disease treatment research communities in pursuit to reveal the mechanism and key targets of ferroptosis because ferroptosis is closely related to the pathophysiological processes of many diseases. Recent studies have shown some key targets, such as glutathione peroxidase 4 (GPX4) and System Xc^-, and several inducers and inhibitors have been developed to regulate these key targets. With the emergence of new ferroptosis targets, studies on inducers and inhibitors have made new developments. The selection and use of inducers and inhibitors are very important for related work. This paper briefly introduces important regulatory targets in the ferroptosis metabolic pathway, lists and categorizes commonly used and recently developed inducers and inhibitors, and discusses their medical application. The paper ends of with potential future research direction for ferroptosis.

Ruxolitinib enhances cytotoxic and apoptotic effects of temozolomide on glioblastoma cells by regulating WNT signaling pathway-related genes

Although temozolomide is the primary chemotherapeutic agent in glioblastoma, current studies have focused on its combinational applications to overcome resistance by targeting multiple pathways. JAK/STAT and WNT are among the essential cancer-related signaling pathways. Ruxolitinib, the first approved JAK1/2 inhibitor, has promise in glioblastoma with its blood-brain barrier (BBB) crossing ability. The mentioned study aims to evaluate the anti-cancer potential of ruxolitinib individually and in combination with temozolomide on glioblastoma cells, brain cancer stem cells (BCSCs), and BBB-forming healthy cells. It also intends to determine the effects of JAK inhibitor treatment in combination with temozolomide on WNT signaling, which is known to cross-talk with the JAK/STAT pathway. The U87MG, BCSC, and HBMEC cell lines were the in vitro models. The cytotoxic and apoptotic effects of ruxolitinib and the combination were determined by the WST-1 test and Annexin V assay, respectively. The expression level changes of WNT signaling pathway genes caused by ruxolitinib and the combination treatments were defined by the qRT-PCR method. Network analysis of significantly upregulated and downregulated genes was performed via the GO KEGG pathway enrichment module of the String V11.5 database. The IC₅₀ value of the ruxolitinib on U87MG glioblastoma cells was determined as 94.07 µM at 24th h. The combination of temozolomide and ruxolitinib had a synergistic effect on U87MG cells at 24th h. The combination index (CI) was determined as 0.796, and ED₆₀ values of ruxolitinib and temozolomide were determined as 89.75 and 391.48 µM, respectively. Ruxolitinib improves the apoptotic effect of temozolomide on glioblastoma cells and brain cancer stem cells. Ruxolitinib regulates the WNT signaling pathway both individually and in combination with temozolomide. Our study indicates the potential of ruxolitinib to increase the cytotoxic and apoptotic activity of temozolomide in glioblastoma cells, also considering CSCs and healthy BBB-forming cells. As supported by gene expression and network analyses, the BBB-crossing agent ruxolitinib promises the potential to increase the efficacy of temozolomide in glioblastoma by affecting multiple signaling pathways in both cancer cells and CSCs.

Cancer stem cell regulated phenotypic plasticity protects metastasized cancer cells from ferroptosis

Cancer cells display phenotypic equilibrium between the stem-like and differentiated states during neoplastic homeostasis. The functional and mechanistic implications of this subpopulation plasticity remain largely unknown. Herein, it is demonstrated that the breast cancer stem cell (BCSC) secretome autonomously compresses the stem cell population. Co-implantation with BCSCs decreases the tumor-initiating capacity yet increases metastasis of accompanying cancer cells, wherein DKK1 is identified as a pivotal factor secreted by BCSCs for such functions. DKK1-promotes differentiation is indispensable for disseminated tumor cell metastatic outgrowth. In contrast, DKK1 inhibitors substantially relieve the metastatic burden by restraining metastatic cells in the dormant state. DKK1 increases the expression of SLC7A11 to protect metastasizing cancer cells from lipid peroxidation and ferroptosis. Combined treatment with a ferroptosis inducer and a DKK1 inhibitor exhibits synergistic effects in diminishing metastasis. Hence, this study deciphers the contribution of CSC-regulated phenotypic plasticity in metastatic colonization and provides therapeutic approaches to limit metastatic outgrowth.

The contribution of breast cancer stem cells (BCSCs) to metastasis needs further elucidation. Here, the authors show that BCSCs secrete DKK1 to protect metastasizing cancer cells from ferroptosis via upregulation of SLC7A11, and further show that the combination of a ferroptosis inducer with a DKK1 inhibitor reduces metastasis.

A novel C-terminal heat shock protein 90 inhibitor that overcomes STAT3-Wnt-β-catenin signaling-mediated drug resistance and adverse effects

Rationale: The heat shock protein (Hsp) system plays important roles in cancer stem cell (CSC) and non-CSC populations. However, limited efficacy due to drug resistance and toxicity are obstacles to clinical use of Hsp90 inhibitors, suggesting the necessity to develop novel Hsp90 inhibitors overcoming these limitations. Methods: The underlying mechanism of resistance to Hsp90 inhibitors was investigated by colony formation assay, sphere formation assay, western blot analysis, and real-time PCR. To develop anticancer Hsp90 inhibitors that overcome the signal transducer and activator of transcription 3 (STAT3)-mediated resistance, we synthesized and screened a series of synthetic deguelin-based compounds in terms of inhibition of colony formation, migration, and viability of non-small cell lung cancer (NSCLC) cells and toxicity to normal cells. Regulation of Hsp90 by the selected compound NCT-80 [5-methoxy-N-(3-methoxy-4-(2-(pyridin-3-yl)ethoxy)phenyl)-2,2-dimethyl-2H-chromene-6-carboxamide] was investigated by immunoprecipitation, drug affinity responsive target stability assay, binding experiments using ATP-agarose beads and biotinylated drug, and docking analysis. The antitumor, antimetastatic, and anti-CSC effects of NCT-80 were examined in vitro and in vivo using various assays such as MTT, colony formation, and migration assays and flow cytometric analysis and tumor xenograft models. Results: We demonstrated a distinct mechanism in which Hsp90 inhibitors that block N-terminal ATP-binding pocket causes transcriptional upregulation of Wnt ligands through Akt- and ERK-mediated activation of STAT3, resulting in NSCLC cell survival in an autocrine or paracrine manner. In addition, NCT-80 effectively reduced viability, colony formation, migration, and CSC-like phenotypes of NSCLC cells and their sublines with acquired resistance to anticancer drugs by inducing apoptosis and inhibiting epithelial-mesenchymal transition and the growth of NSCLC patient-derived xenograft tumors without overt toxicity. With regards to mechanism, NCT-80 directly bound to the C-terminal ATP-binding pocket of Hsp90, disrupting the interaction between Hsp90 and STAT3 and degrading STAT3 protein. Moreover, NCT-80 inhibited chemotherapy- and EGFR TKI-induced programmed cell death ligand 1 expression and potentiated the antitumor effect of chemotherapy in the LLC-Luc allograft model. Conclusions: These data indicate the potential of STAT3/Wnt signaling pathway as a target to overcome resistance to Hsp90 inhibitors and NCT-80 as a novel Hsp90 inhibitor that targets both CSCs and non-CSCs in NSCLC.

Regulation of IL-6/STAT-3/Wnt axis by nifuroxazide dampens colon ulcer in acetic acid-induced ulcerative colitis model: Novel mechanistic insight

AIM

Ulcerative colitis (UC) is a common intestinal problem characterized by the diffusion of colon inflammation and immunity dysregulation. Nifuroxazide, a potent STAT-3 inhibitor, exhibits diverse pharmacological properties. The present study aimed to elucidate a novel anti-colitis mechanism of nifuroxazide against the acetic acid-induced UC model.

METHODS

Rats were grouped into control (received vehicle), UC (2 ml of 5% acetic acid by intrarectal infusion), UC plus sulfasalazine (100 mg/kg/day, P.O.), UC plus nifuroxazide (25 mg/kg/day, P.O.), and UC plus nifuroxazide (50 mg/kg/day, P.O.) and lasted for 6 days.

RESULTS

The present study revealed that nifuroxazide significantly reduced UC measures, hematological changes, and histological alteration. In addition, treatment with nifuroxazide significantly down-regulated serum CRP as well as the colonic expressions of MPO, IL-6, TNF-α, TLR-4, NF-κB-p65, JAK1, STAT-3, DKK1 in a dose-dependent manner. Besides, our results showed that the colonic Wnt expression was up-regulated with nifuroxazide treatment. In a dose-dependent manner, nifuroxazide markedly alleviated acetic acid-induced cellular infiltration and improved ulcer healing by increasing intestinal epithelial cell regeneration.

SIGNIFICANCE

Our results collectively indicate that nifuroxazide is an effective anti-colitis agent through regulation of colon inflammation and proliferation via modulation IL-6/STAT-3/Wnt signaling pathway.

Stat3 loss in mesenchymal progenitors causes Job syndrome-like skeletal defects by reducing Wnt/β-catenin signaling

Job syndrome is a rare genetic disorder caused by STAT3 mutations and primarily characterized by immune dysfunction along with comorbid skeleton developmental abnormalities including osteopenia, recurrent fracture of long bones, and scoliosis. So far, there is no definitive cure for the skeletal defects in Job syndrome, and treatments are limited to management of clinical symptoms only. Here, we have investigated the molecular mechanism whereby Stat3 regulates skeletal development and osteoblast differentiation. We showed that removing Stat3 function in the developing limb mesenchyme or osteoprogenitor cells in mice resulted in shortened and bow limbs with multiple fractures in long bones that resembled the skeleton symptoms in the Job Syndrome. However, Stat3 loss did not alter chondrocyte differentiation and hypertrophy in embryonic development, while osteoblast differentiation was severely reduced. Genome-wide transcriptome analyses as well as biochemical and histological studies showed that Stat3 loss resulted in down-regulation of Wnt/β-catenin signaling. Restoration of Wnt/β-catenin signaling by injecting BIO, a small molecule inhibitor of GSK3, or crossing with a Lrp5 gain of function (GOF) allele, rescued the bone reduction phenotypes due to Stat3 loss to a great extent. These studies uncover the essential functions of Stat3 in maintaining Wnt/β-catenin signaling in early mesenchymal or osteoprogenitor cells and provide evidence that bone defects in the Job Syndrome are likely caused by Wnt/β-catenin signaling reduction due to reduced STAT3 activities in bone development. Enhancing Wnt/β-catenin signaling could be a therapeutic approach to reduce bone symptoms of Job syndrome patients.

JAK inhibition increases bone mass in steady-state conditions and ameliorates pathological bone loss by stimulating osteoblast function

Janus kinase (JAK)-mediated cytokine signaling has emerged as an important therapeutic target for the treatment of inflammatory diseases such as rheumatoid arthritis (RA). Accordingly, JAK inhibitors compose a new class of drugs, among which tofacitinib and baricitinib have been approved for the treatment of RA. Periarticular bone erosions contribute considerably to the pathogenesis of RA. However, although the immunomodulatory aspect of JAK inhibition (JAKi) is well defined, the current knowledge of how JAKi influences bone homeostasis is limited. Here, we assessed the effects of the JAK inhibitors tofacitinib and baricitinib on bone phenotype (i) in mice during steady-state conditions or in mice with bone loss induced by (ii) estrogen-deficiency (ovariectomy) or (iii) inflammation (arthritis) to evaluate whether effects of JAKi on bone metabolism require noninflammatory/inflammatory challenge. In all three models, JAKi increased bone mass, consistent with reducing the ratio of receptor activator of NF-κB ligand/osteoprotegerin in serum. In vitro, effects of tofacitinib and baricitinib on osteoclast and osteoblast differentiation were analyzed. JAKi significantly increased osteoblast function (P < 0.05) but showed no direct effects on osteoclasts. Additionally, mRNA sequencing and ingenuity pathway analyses were performed in osteoblasts exposed to JAKi and revealed robust up-regulation of markers for osteoblast function, such as osteocalcin and Wnt signaling. The anabolic effect of JAKi was illustrated by the stabilization of β-catenin. In humans with RA, JAKi induced bone-anabolic effects as evidenced by repair of arthritic bone erosions. Results support that JAKi is a potent therapeutic tool for increasing osteoblast function and bone formation.

RhoA/Rock activation represents a new mechanism for inactivating Wnt/β-catenin signaling in the aging-associated bone loss

The Wnt/β-catenin signaling pathway appears to be particularly important for bone homeostasis, whereas nuclear accumulation of β-catenin requires the activation of Rac1, a member of the Rho small GTPase family. The aim of the present study was to investigate the role of RhoA/Rho kinase (Rock)-mediated Wnt/β-catenin signaling in the regulation of aging-associated bone loss. We find that Lrp5/6-dependent and Lrp5/6-independent RhoA/Rock activation by Wnt3a activates Jak1/2 to directly phosphorylate Gsk3β at Tyr216, resulting in Gsk3β activation and subsequent β-catenin destabilization. In line with these molecular events, RhoA loss- or gain-of-function in mouse embryonic limb bud ectoderms interacts genetically with Dkk1 gain-of-function to rescue the severe limb truncation phenotypes or to phenocopy the deletion of β-catenin, respectively. Likewise, RhoA loss-of-function in pre-osteoblasts robustly increases bone formation while gain-of-function decreases it. Importantly, high RhoA/Rock activity closely correlates with Jak and Gsk3β activities but inversely correlates with β-catenin signaling activity in bone marrow mesenchymal stromal cells from elderly male humans and mice, whereas systemic inhibition of Rock therefore activates the β-catenin signaling to antagonize aging-associated bone loss. Taken together, these results identify RhoA/Rock-dependent Gsk3β activation and subsequent β-catenin destabilization as a hitherto uncharacterized mechanism controlling limb outgrowth and bone homeostasis.

IL-22 receptor signaling in Paneth cells is critical for their maturation, microbiota colonization, Th17-related immune responses, and anti-Salmonella immunity

Interleukin-22 (IL-22) signaling in the intestines is critical for promoting tissue-protective functions. However, since a diverse array of cell types (absorptive and secretory epithelium as well as stem cells) express IL-22Ra1, a receptor for IL-22, it has been difficult to determine what cell type(s) specifically respond to IL-22 to mediate intestinal mucosal host defense. Here, we report that IL-22 signaling in the small intestine is positively correlated with Paneth cell differentiation programs. Our Il22Ra1fl/fl;Lgr5-EGFP-creERT2-specific knockout mice and, independently, our lineage-tracing findings rule out the involvement of Lgr5+ intestinal stem cell (ISC)-dependent IL-22Ra1 signaling in regulating the lineage commitment of epithelial cells, including Paneth cells. Using novel Paneth cell-specific IL-22Ra1 knockout mice (Il22Ra1fl/fl;Defa6-cre), we show that IL-22 signaling in Paneth cells is required for small intestinal host defense. We show that Paneth cell maturation, antimicrobial effector function, expression of specific WNTs, and organoid morphogenesis are dependent on cell-intrinsic IL-22Ra1 signaling. Furthermore, IL-22 signaling in Paneth cells regulates the intestinal commensal bacteria and microbiota-dependent IL-17A immune responses. Finally, we show ISC and, independently, Paneth cell-specific IL-22Ra1 signaling are critical for providing immunity against Salmonella enterica serovar Typhimurium. Collectively, our findings illustrate a previously unknown role of IL-22 in Paneth cell-mediated small intestinal host defense.

Tweaking EMT and MDR dynamics to constrain triple-negative breast cancer invasiveness by EGFR and Wnt/β-catenin signaling regulation

PURPOSE

Due to a lack of effective targeted therapies, patients with metastatic triple-negative breast cancer (TNBC) have poor clinical outcomes. Epithelial to mesenchymal transition (EMT) is known to contribute to cancer progression, invasiveness and multidrug resistance (MDR). There is a strong correlation between various drug efflux mechanisms, cancer stem cells and tumor microenvironments, which in turn is synchronized by complex signaling crosstalk between EMT and MDR. We hypothesize that combining these regulatory connections with targeted combinatorial therapies may be an effective approach to annihilate the progression/metastasis of TNBC.

METHODS

AlamarBlue assays were used to depict TNBC cell viability, whereas flow cytometry was used to detect apoptotic cell populations, reactive-oxygen species (ROS) levels as well as mitochondrial depolarization. qRT-PCR, Western blotting and confocal microscopy were used to provide molecular-level information of the genes and proteins involved.

RESULTS

Our initial analyses showed that targeting EGFR by either erlotinib (EGFR inhibitor) or lapatinib (EGFR/HER-2 inhibitor) alone was ineffective against TNBC. Interestingly, we subsequently found that a low dose of lapatinib did act as a substrate rather than as an inhibitor facilitating EMT and MDR, leading to metastasis. Additional gene expression studies indicated that co-targeting the EGFR and Wnt/β-catenin pathways with lapatinib and XAV939 (a tankyrase inhibitor) promoted mesenchymal to epithelial transition (MET). Application of these inhibitors led to a 5.62-fold increase in the epithelial marker E-cadherin and a 3.33-fold decrease in the stemness marker EpCAM, with concomitant 1.5-fold and 3.22-fold reductions in the ABC transporters ABCB1 and ABCG2, respectively. These co-targeting effects resulted in overcoming EMT and MDR, which in turn was highlighted by reduced levels of pEGFR, pAKT, pMAPK, pSTAT-3, pGSK-3β and β-catenin.

CONCLUSIONS

Our data indicate that the synergistic action of targeting both the EGFR and Wnt/β-catenin signaling pathways in TNBC cells may open up new avenues for combatting this disease.

SerpinB1 promotes the proliferation of porcine pancreatic stem cells through the STAT3 signaling pathway

Porcine pancreatic stem cells (pPSCs) can be induced to insulin-secreting cells and therefore considered the most promising seeding cells for curing human diabetes in future. However, insufficient pPSCs number is one of the bottleneck problems before its clinical application. SerpinB1 is a serine protease inhibitor in neutrophils and can directly promote the proliferation of β cells. Whether SerpinB1 is involved in pPSC proliferation and differentiation remains unknown. The effects of SerpinB1 on pPSCs proliferation were measured by Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, qRT-PCR, western blot, and flow cytometry assays. We found that pPSCs did not efficiently reach the S phase when SerpinB1 expression was knocked down with short hairpin RNA (sh-SerpinB1), the expression of Cyclin D1, CDK-2, and PCNA also decreased. Meanwhile, cell viability and proliferation ability were both declined. Further analyses showed that the expression level of phosphorylated STAT3/STAT3was downregulated, along with an upregulation of p53 and p21. We used a two-step induction method to induce pPSCs to insulin-secreting cells and found that SerpinB1 expression in insulin-secreting cells was higher than in pPSCs. Meanwhile, the protein expression level of phosphorylated STAT3/STAT3 was increased while p53 and p21 was decreased in induced insulin-secreting cells in comparison with control cells. The insulin-secreting cells derived from the sh-SerpinB1 cells secreted less insulin and showed poor sensitivity to high glucose than control group. However, the insulin-secreting cells derived from the ov-SerpinB1 cells has a quite contrary tendency. In conclusion, this study demonstrates that SerpinB1 promotes the proliferation of pPSCs through the STAT3 signaling pathway, and SerpinB1 is a key factor for maintaining the viability of pPSCs during the transition to insulin-secreting cells.

Src and Fyn define a new signaling cascade activated by canonical and non-canonical Wnt ligands and required for gene transcription and cell invasion

Wnt ligands signal through canonical or non-canonical signaling pathways. Although both routes share common elements, such as the Fz2 receptor, they differ in the co-receptor and in many of the final responses; for instance, whereas canonical Wnts increase β-catenin stability, non-canonical ligands downregulate it. However, both types of ligands stimulate tumor cell invasion. We show here that both the canonical Wnt3a and the non-canonical Wnt5a stimulate Fz2 tyrosine phosphorylation, Fyn binding to Fz2, Fyn activation and Fyn-dependent Stat3 phosphorylation. Wnt3a and Wnt5a require Src for Fz2 tyrosine phosphorylation; Src binds to canonical and non-canonical co-receptors (LRP5/6 and Ror2, respectively) and is activated by Wnt3a and Wnt5a. This Fz2/Fyn/Stat3 branch is incompatible with the classical Fz2/Dvl2 pathway as shown by experiments of over-expression or depletion. Fyn is necessary for transcription of genes associated with invasiveness, such as Snail1, and for activation of cell invasion by both Wnt ligands. Our results extend the knowledge about canonical Wnt pathways, demonstrating additional roles for Fyn in this pathway and describing how this protein kinase is activated by both canonical and non-canonical Wnts.

Targeting Jak/Stat pathway as a therapeutic strategy against SP/CD44+ tumorigenic cells in Akt/β-catenin-driven hepatocellular carcinoma

BACKGROUND & AIMS

Hepatic resection and liver transplantation with adjuvant chemo- and radiotherapy are the mainstay of hepatocellular carcinoma (HCC) treatment, but the 5-year survival rate remains poor because of frequent recurrence and intrahepatic metastasis. Only sorafenib and lenvatinib are currently approved for the first-line treatment of advanced, unresected HCC, but they yield modest survival benefits. Thus, there is a need to identify new therapeutic targets to improve current HCC treatment modalities.

METHODS

The HCC tumor model was generated by hydrodynamic transfection of AKT1 and β-catenin (CTNNB1) oncogenes. Cancer cells with stemness properties were characterized following isolation using side population (SP) and CD44 surface markers by flow cytometry. The effect of Jak/Stat inhibitors was analyzed in vitro by using tumorsphere culture and in vivo using an allograft mouse model.

RESULTS

Co-activation of both Wnt/β-catenin and Akt/mTOR pathways was found in 14.4% of our HCC patient cohort. More importantly, these patients showed poorer survival than those with either Wnt/β-catenin or Akt/mTOR pathway activation alone, demonstrating the clinical relevance of our study. In addition, we observed that Akt/β-catenin tumors contained a subpopulation of cells with stem/progenitor-like characteristics identified through SP analysis and expression of the cancer stem cell-like marker CD44, which may contribute to tumor self-renewal and drug resistance. Consequently, we identified small molecule inhibitors of the Jak/Stat pathway that demonstrated efficacy in mitigating tumor proliferation and formation in Akt/β-catenin-driven HCC.

CONCLUSIONS

In conclusion, we have shown that Akt/β-catenin tumors contain a subpopulation of tumor-initiating cells with stem/progenitor-like characteristics which can be effectively targeted with inhibitors of the Jak/Stat pathway, demonstrating that inhibition of the Jak/Stat pathway could be an alternative method to overcome drug resistance and effectively treat Akt/β-catenin-driven HCC tumors.

LAY SUMMARY

The prognosis for patients with hepatocellular carcinoma is poor, partly because of the lack of effective treatment options for those with more advanced disease. In this study, we identified a subpopulation of cancer cells with stem cell-like properties that were critical for tumor maintenance and growth in a mouse model of hepatocellular carcinoma. Through further experiments, we demonstrated that the Jak/Stat pathway is a promising therapeutic target in hepatocellular carcinoma.

Role of telomerase in the tumour microenvironment

Telomeres are specialized genomic structures that protect chromosomal ends to maintain genomic stability. Telomeric length is primarily regulated by the telomerase complex, essentially consisting of an RNA template (TERC), an enzymatic subunit (telomerase reverse transcriptase, TERT). In humans, telomerase activity is repressed during embryonic differentiation and is absent in most somatic cells. However, it is upregulated or reactivated in 80%-90% of the primary tumours in humans. The human TERT (hTERT) plays a pivotal role in cellular immortality and tumourigenesis. However, the molecular mechanisms of telomerase functioning in cancer have not been fully understood beyond the telomere maintenance. Several research groups, including ours, have demonstrated that hTERT possesses vital functions independent of its telomere maintenance, including angiogenesis, inflammation, cancer cell stemness, and epithelial-mesenchymal transformation (EMT). All these telomere-independent activities of hTERT may contribute to the regulation of the dynamics and homeostasis of the tumour microenvironment (TME), thereby promoting tumour growth and development. Cancer progression and metastasis largely depend upon the interactions between cancer cells and their microenvironment. In this review, the involvement of TERT in the tumour microenvironment and the underlying implications in cancer therapeutics have been summarized.

Balancing STAT Activity as a Therapeutic Strategy

Driven by dysregulated IL-6 family member cytokine signaling in the tumor microenvironment (TME), aberrant signal transducer and activator of transcription (STAT3) and (STAT5) activation have been identified as key contributors to tumorigenesis. Following transformation, persistent STAT3 activation drives the emergence of mesenchymal/cancer-stem cell (CSC) properties, important determinants of metastatic potential and therapy failure. Moreover, STAT3 signaling within tumor-associated macrophages and neutrophils drives secretion of factors that facilitate metastasis and suppress immune cell function. Persistent STAT5 activation is responsible for cancer cell maintenance through suppression of apoptosis and tumor suppressor signaling. Furthermore, STAT5-mediated CD4+/CD25+ regulatory T cells (T_regs) have been implicated in suppression of immunosurveillance. We discuss these roles for STAT3 and STAT5, and weigh the attractiveness of different modes of targeting each cancer therapy. Moreover, we discuss how anti-tumorigenic STATs, including STAT1 and STAT2, may be leveraged to suppress the pro-tumorigenic functions of STAT3/STAT5 signaling.

SLUG Directs the Precursor State of Human Brain Tumor Stem Cells

In glioblastoma (GBM), brain tumor stem cells (BTSCs) encompass heterogenous populations of multipotent, self-renewing, and tumorigenic cells, which have been proposed to be at the root of therapeutic resistance and recurrence. While the functional significance of BTSC heterogeneity remains to be fully determined, we previously distinguished relatively quiescent stem-like precursor state from the more aggressive progenitor-like precursor state. In the present study, we hypothesized that progenitor-like BTSCs arise from stem-like precursors through a mesenchymal transition and drive post-treatment recurrence. We first demonstrate that progenitor-like BTSCs display a more mesenchymal transcriptomic profile. Moreover, we show that both mesenchymal GBMs and progenitor-like BTSCs are characterized by over-activated STAT3/EMT pathways and that SLUG is the primary epithelial to mesenchymal transition (EMT) transcription factor directly regulated by STAT3 in BTSCs. SLUG overexpression in BTSCs enhances invasiveness, promotes inflammation, and shortens survival. Importantly, SLUG overexpression in a quiescent stem-like BTSC line enhances tumorigenesis. Finally, we report that recurrence is associated with SLUG-induced transcriptional changes in both BTSCs and GBM patient samples. Collectively, our findings show that a STAT3-driven precursor state transition, mediated by SLUG, may prime BTSCs to initiate more aggressive mesenchymal recurrence. Targeting the STAT3/SLUG pathway may maintain BTSCs in a quiescent stem-like precursor state, delaying recurrence and improving survival in GBM.

Intracellular Signals Activated by Canonical Wnt Ligands Independent of GSK3 Inhibition and β-Catenin Stabilization

In contrast to non-canonical ligands, canonical Wnts promote the stabilization of β-catenin, which is a prerequisite for formation of the TCF4/β-catenin transcriptional complex and activation of its target genes. This pathway is initiated by binding of Wnt ligands to the Frizzled/LRP5/6 receptor complex, and it increases the half-life of β-catenin by precluding the phosphorylation of β-catenin by GSK3 and its binding to the βTrCP1 ubiquitin ligase. Other intercellular signals are also activated by Wnt ligands that do not inhibit GSK3 and increase β-catenin protein but that either facilitate β-catenin transcriptional activity or stimulate other transcriptional factors that cooperate with it. In this review, we describe the layers of complexity of these signals and discuss their crosstalk with β-catenin in activation of transcriptional targets.

Stat3 in osteocytes mediates osteogenic response to loading

Signal transducer and activator of transcription 3 (Stat3) is a member of the Stat family of proteins involved in signaling in many different cell types, including osteocytes. Osteocytes are considered major mechanosensing cells in bone due to their intricate dendritic networks able to sense changes in physical force and to orchestrate the response of osteoclasts and osteoblasts. We examined the role of Stat3 in osteocytes by generating mice lacking Stat3 in these cells using the Dmp-1(8kb)-Cre promoter (Stat3cKO mice). Compared to age-matched littermate controls, Stat3cKO mice of either sex (18 weeks old) exhibit reduced bone formation indices, decreased osteoblasts and increased osteoclasts, and altered material properties, without detectable changes in bone mineral density (BMD) or content of either trabecular or cortical bone. In addition, Stat3cKO mice of either sex show significantly decreased load-induced bone formation. Furthermore, pharmacologic inhibition of Stat3 in osteocytes in vitro with WP1066 blocked the increase in cytosolic calcium induced by ATP, a mediator of the cellular responses to sheer stress. WP1066 also increased reactive oxygen species (ROS) production in cultured MLO-Y4 osteocytes. These data demonstrate that Stat3 is a critical mediator of mechanical signals received by osteocytes and suggest that osteocytic Stat3 is a potential therapeutic target to stimulate bone anabolism.

Small-molecule inhibitors and the salivary gland epithelium in Sjögren's syndrome

INTRODUCTION

The salivary gland (SG) in primary Sjögren's syndrome (pSS) is characterized by its lack of function (hyposalivation) and lymphocytic invasion. Small-molecule inhibitors (SMIs) are a new class of drugs, whose diminutive size permits diffusion into cells. SMIs targeting components of the immune system are eagerly being trialed for their potential therapeutic utility in pSS. Neglected until now, however, is a discussion of the potential effects of SMIs on the SG epithelium.

AREAS COVERED

We begin by reminding the reader of the SG epithelial compartment, its complicity in inflammatory milieu formation in pSS, and categories of SMIs which merit attention. We discuss each SMI category, including pre-clinical data concerning pSS and likely consequences of their application on the SG epithelium.

EXPERT OPINION

Recovery of saliva production in pSS requires restoring the function of the SG epithelium, not solely on inflammation resolution. Many SMIs, for example, those blocking JAK-STAT signaling, interfere with critical epithelial cell pathways, most notably EGF signaling. If the effect of SMIs on SG epithelium is ignored, recovery of SG function will be challenging. We predict that NFκB signaling blockade will impart the least SG epithelium damage whilst reducing inflammation and facilitating recovery from hyposalivation in pSS.

Resolvin D2 Induces Resolution of Periapical Inflammation and Promotes Healing of Periapical Lesions in Rat Periapical Periodontitis

Periapical periodontitis results from pulpal infection leading to pulpal necrosis and resorption of periapical bone. The current treatment is root canal therapy, which attempts to eliminate infection and necrotic tissue. But, in some cases periapical inflammation doesn't resolve even after treatment. Resolvins belongs to a large family of specialized pro-resolving lipid mediators that actively resolves inflammation signaling via specific receptors. Resolvin D2 (RvD2), a metabolite of docosahexaenoic acid (DHA), was tested as an intracanal medicament in rats in vivo. Mechanism was evaluated in rat primary dental pulp cells (DPCs) in vitro. The results demonstrate that RvD2 reduces inflammatory cell infiltrate, periapical lesion size, and fosters pulp like tissue regeneration and healing of periapical lesion. RvD2 enhanced expression of its receptor, GPR18, dentin matrix acidic phosphoprotein 1 (DMP1) and mineralization in vivo and in vitro. Moreover, RvD2 induces phosphorylation of Stat3 transcription factor in dental pulp cells. We conclude that intracanal treatment with RvD2 resolves inflammation and promoting calcification around root apex and healing of periapical bone lesions. The data suggest that RvD2 induces active resolution of inflammation with pulp-like tissue regeneration after root canal infection and thus maybe suitable for treating periapical lesions.

The Disruption of the β-Catenin/TCF-1/STAT3 Signaling Axis by 4-Acetylantroquinonol B Inhibits the Tumorigenesis and Cancer Stem-Cell-Like Properties of Glioblastoma Cells, In Vitro and In Vivo

BACKGROUND

Glioblastoma (GBM), a malignant form of glioma, is characterized by resistance to therapy and poor prognosis. Accumulating evidence shows that the initiation, propagation, and recurrence of GBM is attributable to the presence of GBM stem cells (GBM-CSCs).

EXPERIMENTAL APPROACH

Herein, we investigated the effect of 4-Acetylantroquinonol B (4-AAQB), a bioactive isolate of Antrodia cinnamomea, on GBM cell viability, oncogenic, and CSCs-like activities.

RESULTS

We observed that aberrant expression of catenin is characteristic of GBM, compared to other glioma types (p = 0.0001, log-rank test = 475.2), and correlates with poor prognosis of GBM patients. Lower grade glioma and glioblastoma patients (n = 1152) with low catenin expression had 25% and 21.5% better overall survival than those with high catenin expression at the 5 and 10-year time-points, respectively (p = 3.57e-11, log-rank test = 43.8). Immunohistochemistry demonstrated that compared with adjacent non-tumor brain tissue, primary and recurrent GBM exhibited enhanced catenin expression (~10-fold, p < 0.001). Western blot analysis showed that 4-AAQB significantly downregulated β-catenin and dysregulated the catenin/LEF1/Stat3 signaling axis in U87MG and DBTRG-05MG cells, dose-dependently. 4-AAQB⁻induced downregulation of catenin positively correlated with reduced Sox2 and Oct4 nuclear expression in the cells. Furthermore, 4-AAQB markedly reduced the viability of U87MG and DBTRG-05MG cells with 48 h IC50 of 9.2 M and 12.5 M, respectively, effectively inhibited the nuclear catenin, limited the migration and invasion of GBM cells, with concurrent downregulation of catenin, vimentin, and slug; similarly, colony and tumorsphere formation was significantly attenuated with reduced expression of c-Myc and KLF4 proteins.

CONCLUSIONS

Summarily, we show for the first time that 4-AAQB suppresses the tumor-promoting catenin/LEF1/Stat3 signaling, and inhibited CSCs-induced oncogenic activities in GBM in vitro, with in vivo validation; thus projecting 4-AAQB as a potent therapeutic agent for anti-GBM target therapy.

STAT3 suppresses Wnt/β-catenin signaling during the induction phase of primary Myf5+ brown adipogenesis

Thermogenic fat is a promising target for new therapies in diabetes and obesity. Understanding how thermogenic fat develops is important to develop rational strategies to treat obesity. Previously, we have shown that Tyk2 and STAT3, part of the JAK-STAT pathway, are necessary for proper development of classical brown fat. Using primary preadipocytes isolated from newborn mice we demonstrate that STAT3 is required for differentiation and robust expression of Uncoupling Protein 1 (UCP1). We also confirm that STAT3 is necessary during the early induction stage of differentiation and is dispensable during the later terminal differentiation stage. The inability of STAT3-/- preadipocytes to differentiate can be rescued using Wnt ligand secretion inhibitors when applied during the induction stage. Through chemical inhibition and RNAi, we show that it is the canonical β-catenin pathway that is responsible for the block in differentiation; inhibition or knockdown of β-catenin can fully rescue adipogenesis and UCP1 expression in the STAT3-/- adipocytes. During the induction stage, Wnts 1, 3a, and 10b have increased expression in the STAT3-/- adipocytes, potentially explaining the increased levels and activity of β-catenin. Our results for the first time point towards an interaction between the JAK/STAT pathway and the Wnt/β-catenin pathway during the early stages of in-vitro adipogenesis.

WNT6 is a novel oncogenic prognostic biomarker in human glioblastoma

Glioblastoma (GBM) is a universally fatal brain cancer, for which novel therapies targeting specific underlying oncogenic events are urgently needed. While the WNT pathway has been shown to be frequently activated in GBM, constituting a potential therapeutic target, the relevance of WNT6, an activator of this pathway, remains unknown.

Methods: WNT6 protein and mRNA levels were evaluated in GBM. WNT6 levels were silenced or overexpressed in GBM cells to assess functional effects in vitro and in vivo. Phospho-kinase arrays and TCF/LEF reporter assays were used to identify WNT6-signaling pathways, and significant associations with stem cell features and cancer-related pathways were validated in patients. Survival analyses were performed with Cox regression and Log-rank tests. Meta-analyses were used to calculate the estimated pooled effect.

Results: We show that WNT6 is significantly overexpressed in GBMs, as compared to lower-grade gliomas and normal brain, at mRNA and protein levels. Functionally, WNT6 increases typical oncogenic activities in GBM cells, including viability, proliferation, glioma stem cell capacity, invasion, migration, and resistance to temozolomide chemotherapy. Concordantly, in in vivo orthotopic GBM mice models, using both overexpressing and silencing models, WNT6 expression was associated with shorter overall survival, and increased features of tumor aggressiveness. Mechanistically, WNT6 contributes to activate typical oncogenic pathways, including Src and STAT, which intertwined with the WNT pathway may be critical effectors of WNT6-associated aggressiveness in GBM. Clinically, we establish WNT6 as an independent prognostic biomarker of shorter survival in GBM patients from several independent cohorts.

Conclusion: Our findings establish WNT6 as a novel oncogene in GBM, opening opportunities to develop more rational therapies to treat this highly aggressive tumor.

Lycopene treatment inhibits activation of Jak1/Stat3 and Wnt/β-catenin signaling and attenuates hyperproliferation in gastric epithelial cells

Helicobacter pylori (H pylori) colonizes the human stomach and increases the risk of gastric diseases including gastric cancer. H pylori increases reactive oxygen species (ROS), which activate Janus-activator kinase 1 (Jak1)/signal transducers and activators of transcription 3 (Stat3) in gastric epithelial cells. ROS mediate hyperproliferation, a hallmark of carcinogenesis, by activating Wnt/β-catenin signaling in various cells. Lycopene is a potent antioxidant exhibiting anticancer effects. We hypothesized that lycopene may inhibit H pylori-induced hyperproliferation by suppressing ROS-mediated activation of Jak1/Stat3 and Wnt/β-catenin signaling, and β-catenin target gene expression in gastric epithelial cells. We determined cell viability, ROS levels, and the protein levels of phospho- and total Jak1/Stat3, Wnt/β-catenin signaling molecules, Wnt-1, lipoprotein-related protein 5, and β-catenin target oncogenes (c-Myc and cyclin E) in H pylori-infected gastric epithelial AGS cells. The Jak1/Stat3 inhibitor AG490 served as the control treatment. The significance of the differences among groups was calculated using the 1-way analysis of variance followed by Newman-Keuls post hoc tests. The results show that lycopene reduced ROS levels and inhibited Jak1/Stat3 activation, alteration of Wnt/β-catenin multiprotein complex molecules, expression of c-Myc and cyclin E, and cell proliferation in H pylori-infected AGS cells. AG490 similarly inhibited H pylori-induced cell proliferation, alteration of Wnt/β-catenin multiprotein complex molecules, and oncogene expression. H pylori increased the levels of Wnt-1 and its receptor lipoprotein-related protein 5; this increase was inhibited by either lycopene or AG490 in AGS cells. In conclusion, lycopene inhibits ROS-mediated activation of Jak1/Stat3 and Wnt/β-catenin signaling and, thus, oncogene expression in relation to hyperproliferation in H pylori-infected gastric epithelial cells. Lycopene might be a potential and promising nutrient for preventing H pylori-associated gastric diseases including gastric cancer.

LncRNA PTCSC3 affects drug resistance of anaplastic thyroid cancer through STAT3/INO80 pathway

BACKGROUND

LncRNA PTCSC3 is a tumor suppressor in thyroid cancer, and its role in drug resistance of anaplastic thyroid cancer (ATC) to chemotherapy drug doxorubicin was investigated in this study.

METHODS

Expression of RNA and protein was analyzed by qRT-PCR and western blot, respectively. Flow cytometry was used to analyze the expression rate of CD133⁺ cells. The endogenous expression of related genes was modulated by recombinant plasmids and cell transfection. Combination condition and interaction between PTCSC3 and STAT3 were determined by RIP and RNA pull-down assay, respectively. MTT assay was performed to detect cytotoxicity. Chromatin immunoprecipitation was conducted to identify interactions between STAT3 and DNA promoter of INO80.

RESULTS

LncRNA PTCSC3 was low-expressed in ATC tissues and cells. Over-expressed PTCSC3 inhibited the drug resistance of ATC to doxorubicin. PTCSC3 negatively regulated STAT3, and STAT3 promoted expression of INO80. PTCSC3 regulated INO80 through STAT3. PTCSC3 suppressed stem cells properties and drug resistance of ATC to doxorubicin.

CONCLUSION

LncRNA PTCSC3 inhibits INO80 expression by negatively regulating STAT3, and thereby attenuating drug resistance of ATC to chemotherapy drug doxorubicin.

A growing field: The regulation of axonal regeneration by Wnt signaling

The canonical Wnt/β-catenin pathway is a highly conserved signaling cascade that plays critical roles during embryogenesis. Wnt ligands regulate axonal extension, growth cone guidance and synaptogenesis throughout the developing central nervous system (CNS). Recently, studies in mammalian and fish model systems have demonstrated that Wnt/β-catenin signaling also promotes axonal regeneration in the adult optic nerve and spinal cord after injury, raising the possibility that Wnt could be developed as a therapeutic strategy. In this review, we summarize experimental evidence that reveals novel roles for Wnt signaling in the injured CNS, and discuss possible mechanisms by which Wnt ligands could overcome molecular barriers inhibiting axonal growth to promote regeneration. A central challenge in the neuroscience field is developing therapeutic strategies that induce robust axonal regeneration. Although adult axons have the capacity to respond to axonal guidance molecules after injury, there are several major obstacles for axonal growth, including extensive neuronal death, glial scars at the injury site, and lack of axonal guidance signals. Research in rodents demonstrated that activation of Wnt/β-catenin signaling in retinal neurons and radial glia induced neuronal survival and axonal growth, but that activation within reactive glia at the injury site promoted proliferation and glial scar formation. Studies in zebrafish spinal cord injury models confirm an axonal regenerative role for Wnt/β-catenin signaling and identified the cell types responsible. Additionally, in vitro and in vivo studies demonstrated that Wnt induces axonal and neurite growth through transcription-dependent effects of its central mediator β-catenin, potentially by inducing regeneration-promoting genes. Canonical Wnt signaling may also function through transcription-independent interactions of β-catenin with cytoskeletal elements, which could stabilize growing axons and control growth cone movement. Therefore, these studies suggest that Wnt-induced pathways responsible for regulating axonal growth during embryogenesis could be repurposed to promote axonal growth after injury.

Hypotheses on the Potential of Rice Bran Intake to Prevent Gastrointestinal Cancer through the Modulation of Oxidative Stress

Previous studies have suggested the potential involvement of oxidative stress in gastrointestinal cancers. In light of this, research efforts have been focused on the potential of dietary antioxidant intake to prevent gastrointestinal cancer through the modulation of oxidative stress. Rice bran, a by-product of rice milling, has been shown to contain an abundance of phytochemicals, which are dietary antioxidants. To date, a number of studies have shown the antioxidative effect of rice bran intake, and some demonstrated that such an effect may contribute to gastrointestinal cancer prevention, largely through the antioxidative properties of rice bran phytochemicals. In addition, these phytochemicals were shown to provide protection against cancer through mechanisms linked to oxidative stress, including β-catenin-mediated cell proliferation and inflammation. The present article provides an overview of current evidence for the antioxidative properties of rice bran and its phytochemicals, and for the potential of such properties in cancer prevention through the oxidative-stress-linked mechanisms mentioned above. The article also highlights the need for an evaluation of the effectiveness of rice bran dietary interventions among cancer survivors in ameliorating oxidative stress and reducing the level of gastrointestinal cancer biomarkers, thereby establishing the potential of such interventions among these individuals in the prevention of cancer recurrence.

Alteration of SHP-1/p-STAT3 Signaling: A Potential Target for Anticancer Therapy

The Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 1 (SHP-1), a non-receptor protein tyrosine phosphatase, has been reported as a negative regulator of phosphorylated signal transducer and activator of transcription 3 (STAT3) and linked to tumor development. In this present review, we will discuss the importance and function of SHP-1/p-STAT3 signaling in nonmalignant conditions as well as malignancies, its cross-talk with other pathways, the current clinical development and the potential role of inhibitors of this pathway in anticancer therapy and clinical relevance of SHP-1/p-STAT3 in cancers. Lastly, we will summarize and highlight work involving novel drugs/compounds targeting SHP-1/p-STAT3 signaling and combined strategies that were/are discovered in our and our colleagues’ laboratories.

Increased susceptibility to fundus camera-delivered light-induced retinal degeneration in mice deficient in oxidative stress response proteins

Oxidative stress is an important contributor to the pathogenesis of many retinal diseases including age-related macular degeneration and retinal dystrophies. Light-induced retinal degeneration (LIRD) can serve as a model in which to study the response of the retina to stress. Of note, many genetic mutant mice are in a C57BL/6 J background and are thus resistant to the usual LIRD models. We recently developed a new model of fundus camera-delivered light-induced retinal degeneration (FCD-LIRD) which is effective in strains of mice expressing the light-resistant variant of RPE65 (450Met), including C57BL/6 J. In this work we investigated whether FCD-LIRD would be useful as a model in which to test the effect of genetic mutations on the response of the retina to stress. Furthermore, we tested whether oxidative stress plays an important role in the setting of this new FCD-LIRD model. FCD-LIRD was applied to C57BL/6 J mice and to mice simultaneously deficient in three proteins that are important in the response of the retina to oxidative stress (SOD1, DJ-1 and Parkin). Using fundus photography, we found that retinal damage was dramatically increased in the SOD1/DJ-1/Parkin deficient mice compared to C57BL/6 J. Outer retinal OCT volume and RPE cell morphology analysis in ZO-1-stained flat mounts added support to these findings. Gene expression analysis confirmed a strong oxidative stress response after FCD-LIRD, which was differentially altered in the SOD1/DJ1/Parkin deficient mice. We conclude that FCD-LIRD is useful to study the effect of genetic mutations on the response of the retina to light stress in light-resistant strains of mice. Furthermore, oxidative stress seems to be an important component of FCD-LIRD. Finally, we have established protocols to quantify the effect of FCD-LIRD on the retina and RPE which will be useful for future studies. Further dissection of the mechanisms by which the retina responds to light-induced oxidative stress may result in new strategies to modulate this response, which could lead to a reduction in retinal and RPE damage.

Wnt signaling promotes axonal regeneration following optic nerve injury in the mouse

Adult mammalian CNS axons generally do not regenerate, creating an obstacle to effective repair and recovery after neuronal injury. The canonical Wnt/β-catenin signaling pathway is an essential signal transduction cascade that regulates axon growth and neurite extension in the developing mammalian embryo. In this study, we investigated whether a Wnt/β-catenin signaling activator could be repurposed to induce regeneration in the adult CNS after axonal injury. We used a retinal ganglion cell (RGC) axon crush injury model in a transgenic Wnt reporter mouse, and intravitreal injections were used to deliver Wnt3a or saline to the RGC cell bodies within the retina. Our findings demonstrated that Wnt3a induced Wnt signaling in RGCs and resulted in significant axonal regrowth past the lesion site when measured at two and four weeks post-injury. Furthermore, Wnt3a-injected eyes showed increased survival of RGCs and significantly higher pattern electroretinography (PERG) amplitudes compared to the control. Additionally, Wnt3a-induced axonal regeneration and RGC survival were associated with elevated activation of the transcription factor Stat3, and reducing expression of Stat3 using a conditional Stat3 knock-out mouse line led to diminished Wnt3a-dependent axonal regeneration and RGC survival. Therefore, these findings reveal a novel role for retinal Wnt signaling in axonal regrowth and RGC survival following axonal injury, which may lead to the development of novel therapies for axonal regeneration.