Glycogen synthase kinase 3 beta: can it be a target for oral cancer

PSAT1 mediated EMT of colorectal cancer cells by regulating Pl3K/AKT signaling pathway

Background: The metastasis of colorectal cancer (CRC) is one of the significant barriers impeding its treated consequence and bring about high mortality, less surgical resection rate and poor prognosis of CRC patients. PSAT1 is an enzyme involved in serine biosynthesis. The studies showed that PSAT1 plays the part of a crucial character in the regulation of tumor metastasis. And Epithelial-Mesenchymal Transition (EMT) is a process of cell reprogramming in which epithelialcells obtain mesenchymal phenotypes. It is a crucial course in promoting cell metastasis and the progression of malignant tumors. The relationship between PSAT1 and EMT in colorectal cancer, as well as the underlying molecular mechanisms, remains enigmatic and warrants thorough exploration. These findings suggest that PSAT1 may serve as a promising therapeutic target for mitigating colorectal cancer metastasis and holds the potential to emerge as a valuable prognostic biomarker in forthcoming research endeavors. Materials and Methods: Utilizing TCGA dataset in conjunction with clinical CRC specimens, our initial focus was directed towards an in-depth examination of PSAT1 expression within CRC, specifically exploring its potential correlation with the adverse prognostic outcomes experienced by patients. Furthermore, we conducted a comprehensive investigation into the regulatory influence exerted by PSAT1 on CRC through the utilization of siRNA knockdown techniques. In the realm of in vitro experimentation, we meticulously evaluated the impact of PSAT1 on various facets of CRC progression, including cell migration, invasion, proliferation, and colony formation. In order to elucidate the intricate effects in question, we adopted a multifaceted methodology that encompassed a range of assays and analyses. These included wound healing assays, transwell assays, utilization of the Cell Counting Kit-8 (CCK-8) assay, and colony formation assays. By employing this diverse array of investigative techniques, we were able to achieve a comprehensive comprehension of the multifaceted role that PSAT1 plays in the pathogenesis of colorectal cancer. This multifarious analysis greatly contributed to our in-depth understanding of the complex mechanisms at play in colorectal cancer pathogenesis. Using WB and PCR experiments, we found that PSAT1 has a role in regulating EMT development in CRC.In terms of mechanism, we found that PSAT1 affected EMT by Regulating Pl3K/AKT Signaling Pathway. Results: Our investigation revealed a noteworthy down-regulation of PSAT1 expression in CRC specimens. Importantly, this down-regulation exhibited a significant positive correlation with the unfavorable prognosis of patients afflicted with CRC. Functionally, our study showcased that the siRNA-mediated knockdown of PSAT1 markedly enhanced various key aspects of CRC pathogenesis in an in vitro setting. Specifically, this included a substantial promotion of CRC cell migration, invasion, proliferation, and colony formation. Moreover, the silencing of PSAT1 also demonstrated a substantial promotion of the EMT process. Intriguingly, our research unveiled a hitherto unexplored mechanism underlying the regulatory role of PSAT1 in CRC and EMT. We have established, for the first time, that PSAT1 exerts its influence by modulating the activation of the PI3K/AKT Signaling Pathway. This mechanistic insight provides a valuable contribution to the understanding of the molecular underpinnings of CRC progression and EMT induction mediated by PSAT1. Conclusions: In unison, our research findings shed light on the previously uncharted and significant role of the PSAT1/PI3K/AKT axis in the initiation of the EMT process in CRC. Furthermore, our discoveries introduce a novel biomarker with potential implications for the clinical diagnosis and treatment of CRC.

Abnormal upregulation of NUBP2 contributes to cancer progression in colorectal cancer

Colorectal cancer (CRC), a digestive tract malignancy with high mortality and morbidity, lacks effective biomarkers for clinical prognosis due to its complex molecular pathogenesis. Nucleotide binding protein 2 (NUBP2) plays a vital role in the assembly of cytosolic Fe/S protein and has been implicated in cancer progression. In this study, we found that NUBP2 was highly expressed in CRC by TCGA database analysis. Subsequently, we verified the expression of NUBP2 in CRC tumor tissues and para-carcinoma tissues using IHC staining, and further investigated its association with clinicopathological parameters. In vitro cell experiments were conducted to assess the role of NUBP2 in CRC by evaluating cell proliferation, migration, and apoptosis upon NUBP2 dysregulation. Furthermore, we established a subcutaneous CRC model to evaluate the impact of NUBP2 on tumor growth in vivo. Additionally, we performed mechanistic exploration using a Human Phospho-Kinase Array-Membrane. Our results showed higher expression of NUBP2 in CRC tissues, which positively correlated with the pathological stage, indicating its involvement in tumor malignancy. Functional studies demonstrated that NUBP2 knockdown reduced cell proliferation, increased apoptosis, and impaired migration ability. Moreover, NUBP2 knockdown inhibited tumor growth in mice. We also observed significant changes in the phosphorylation level of GSK3β upon NUBP2 knockdown or overexpression. Additionally, treatment with CHIR-99021 HCl, an inhibitor of GSK3β, reversed the malignant phenotype induced by NUBP2 overexpression. Overall, this study elucidated the functional role of NUBP2 in CRC progression both in vitro and in vivo, providing insights into the molecular mechanisms underlying CRC and potential implications for targeted therapeutic strategies.

Expression of tumoral GSK3-β, PD-L1, and CD8 cell density in urothelial carcinomas, association with tumor grade and overall survival

Bladder cancer is the most common malignancy in the urinary tract, and is biologically and clinically quite heterogeneous. Around 90% of diagnoses are made in the 6th decade, being more prevalent in males. The programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) axis play a putative role in immune checkpoint and as a means through which cancer evades the immune system. Inhibition of the glicogênio synthase kinase (GSK) 3 leads to the downregulation of PD-1 via upregulation of the transcription factor Tbet. The use of biomarkers PD-L1 and GSK-3β and evaluation of the immune infiltrate have very promising correlations with urothelial carcinoma prognosis and treatment prediction.

OBJECTIVE

To investigate the protein expression of PD-L1 and GSK-3β and the CD8-positive immune infiltrates in bladder carcinomas.

MATERIALS AND METHODS

This was a cross-sectional study of 140 samples of urothelial carcinomas from 2015 to 2018. Automated digitally assisted scoring and conventional analyses of the markers of GSK-3β (27C10), CD8 (7103β) and PDL-1 (22c3), were reviewed by two pathologists independently and a histologic score was calculated. The density of CD8 was also measured.

RESULTS

The immunoexpression of GSK-3β (91%) was presented in most samples, PD-L1 in 62.9% and CD8 cells present in 46.3% of cases. When analyzed in conjunction, the levels of GSK-3β and PD-L1 (P = 0.033), and CD8 and PD-L1 (P<0.002) showed significant correlations. No significant associations were observed between GSK-3β and CD8. The positivity of GSK-3β and PD-L1 was predominant in high-grade tumors.

CONCLUSION

Despite the tumor microenvironment heterogeneity, the expression of CD8, GSK-3β and PDL1 could be valuable and GSK-3β could be a potential target in advanced bladder cancer, especially in the context of immunotherapy.

Mechanism of ASK1 involvement in liver diseases and related potential therapeutic targets: A critical pathway molecule worth investigating

Since the discovery of apoptosis signal-regulated kinase 1 (ASK1), the signal transduction mechanism and pathophysiological process involved in its regulation have been continuously revealed. Many previous studies have identified that ASK1 is involved and plays a critical role in the development of diseases affecting the nervous, cardiac, renal, and other systems. As a mitogen-activated protein kinase (MAPK) kinase kinase, ASK1 mediates apoptosis, necrosis, inflammation, and other pathological processes by activating its downstream c-Jun N-terminal kinase (JNK)/p38 MAPK. Owing to the important role of ASK1, an increasing number of studies in recent years have focused on its status in liver-related diseases. In this paper, we review the mechanisms and targets of ASK1 in liver-related diseases to emphasize its important role in the development of liver disease.

Identification of Potential miRNA-mRNA Regulatory Network in the Development of Oral Cancer

Background

Oral cancer is a difficult question in modern medical system, and there are few effective strategies to completely heal these diseases. This research investigated the miRNA-mRNA network in oral cancer development via bioinformatics excavation.

Methods

GSE28100 and GSE23558 in the GEO database were selected for bioinformatics analysis. The datasets were analyzed with GEO2R to obtain the related matrix files. The hot plot and heatmap of the matrix files were drawn with R language. The MiRDIP database was applied to predict and screen the targets of miRNAs. The DEGs in the matrix files were analyzed with the DAVID database and visualized with R language for enrichment analysis. The PPI-network of the DEGs was established with the STRING database and Cytoscape. Besides, the miRNA-mRNA was visualized by Cytoscape.

Results

35 genes were identified as the DEGs in GES28100. 1651 genes were identified as the DEGs in GSE23558. 143 common genes in the targets of miRNAs in GSE28100 and the DEGs in GSE the targets of DEGs in GES28100 and common genes were enriched in the PI3K/AKT pathway, MAPK pathway, etc. The DEGs in GSE28100 and GSE23558 were involved in the regulations of transcription from RNA polymerase II promoter and DNA transcription. The DEGs in GSE28100 and GSE23558 were established with the miRNA-mRNA network.

Conclusion

This research identified miR-15b-5p, miR-199a-3p, miR-21-5p, miR-424-5p, and miR-454-3p as the biomarker of oral cancer and established the miRNA-mRNA network in oral progression.

Decrypting a path based approach for identifying the interplay between PI3K and GSK3 signaling cascade from the perspective of cancer

Cancer is one of those leading diseases worldwide, which takes millions of lives every year. Researchers are continuously looking for specific approaches to eradicate the deadly disease, ensuring minimal adverse effects along with more therapeutic significance. Targeting of different aberrantly regulated signaling pathways, involved in cancer, is surely one of the revolutionary chemotherapeutic approach. In this instance, GSK3 and PI3K signaling cascades are considered as important role player for both the oncogenic activation and inactivation which further leads to cancer proliferation and metastasis. In this review, we have discussed the potential role of GSK3 and PI3K signaling in cancer, and we further established the crosstalk between PI3K and GSK3 signaling, through showcasing their cross activation, cross inhibition and convergence pathways in association with cancer. We also exhibited the effect of GSK3 on the efficacy of PI3K inhibitors to overcome the drug resistance and preventing the cell proliferation, metastasis in a combinatorial way with GSK3 inhibitors for a better treatment strategy in clinical settings.

ERK-mediated upregulation of matrix metalloproteinase-2 promotes the invasiveness in human oral squamous cell carcinoma (OSCC)

BACKGROUND

Loco-regional invasion is commonly found in oral squamous cell carcinoma (OSCC) and is associated with its poor survival rate. Matrix metalloproteinase-2 (MMP-2) has been implicated in OSCC progression, but its regulation is poorly understood.

MATERIALS AND METHODS

Here, one hundred twenty-seven different post-operated human oral cancer tissue samples were analyzed. The messenger RNA (mRNA) expression, protein expression, and MMP-2 activity and MT1-MMP, TIMP-2, and TFs (NFκB, AP1, Sp1, and Twist) were observed semi-quantitative RT-PCR, western blotting, and gelatin zymography. In addition, OSCC derived Cal-27, SCC4/9 cells, photochemical ECGC, and MAPK-pathway inhibitor PD98059 were utilized for in vitro testing and wound healing assay.

RESULT

s: Increased protein and activity level of MMP-2 was detected in non-invasive (N₀) and invasive (N_1-3) oral tumors as compared to the control (adjacent normal) samples. MMP-2 protein and mRNA expression were positively associated with the TFs and MT1-MMP, negatively associated with TIMP-2 expression. Similarly, the MMP-2 expression/activity was related to several signal-transduction pathways like ERK1/2 and wnt-β-catenin pathways. Treatment of ECGC/MEK inhibitor (PD98059) diminished MMP-2 activity and invasion/migration potential in OSCC.

CONCLUSION

Our research suggests that the ERK1/2 driven overexpression/activation of MMP-2 was linked with the overall OSCC invasion and metastasis. Treatment of MEK inhibitor (PD98059) and ECGC diminished MMP-2 activity and thus could be exploited as a therapeutic strategy to control the invasive OSCC.

The two faces of autophagy in oral squamous cell carcinoma

OBJECTIVE

To undertake a comprehensive review of the current knowledge and understanding of autophagy in oral squamous cell carcinoma (OSCC), focusing on putative roles in tumour suppression and survival along with the influence of this cell death pathway on the development of resistance to chemotherapeutic treatment.

DESIGN

Several well utilised databases (PubMed, Medline, Google Scholar) were searched for the relevant literature using terms and keywords including but not limited too; autophagy and cancer, autophagy and OSCC, tumour survival, autophagy and oral microbiome, autophagy immunogenicity, OSCC chemoresistance.

RESULTS

Up-regulation of autophagy has been shown to promote tumour cell survival in the tumour microenvironment while in healthy cells, autophagy induction acts to prevent severe DNA mutations that can lead to cancer. Cancers utilise the autophagy pathway to promote survival during the stress of chemotherapeutic treatment and can induce resistance to chemotherapeutic drugs CONCLUSION: The ambiguous role of autophagy within cancers is still problematic in clinical fields. Within OSCC understanding whether autophagy plays a preventive or causative role is essential and may be beneficial in determining how modulation of this pathway may impact on OSSC and oral cancer patients.

Anti-fibrotic effect of 6-bromo-indirubin-3'-oxime (6-BIO) via regulation of activator protein-1 (AP-1) and specificity protein-1 (SP-1) transcription factors in kidney cells

PAI-1 and CTGF are overexpressed in kidney diseases and cause fibrosis of the lungs, liver, and kidneys. We used a rat model of unilateral ureteral obstruction (UUO) to investigate whether 6-BIO, a glycogen synthase kinase-3β inhibitor, attenuated fibrosis by inhibiting PAI-1 and CTGF in vivo. Additionally, TGFβ-induced cellular fibrosis was observed in vitro using the human kidney proximal tubular epithelial cells (HK-2), and rat interstitial fibroblasts (NRK49F). Expression of fibrosis-related proteins and signaling molecules such as PAI-1, CTGF, TGFβ, αSMA, SMAD, and MAPK were determined in HK-2 and NRK49F cells using immunoblotting. To identify the transcription factors that regulate the expression of PAI-1 and CTGF the promoter activities of AP-1 and SP-1 were analyzed using luciferase assays. Confocal microscopy was used to observe the co-localization of AP-1 and SP-1 to PAI-1 and CTGF. Expression of PAI-1, CTGF, TGFβ, and α-SMA increased in UUO model as well as in TGFβ-treated HK-2 and NRK49F cells. Furthermore, UUO and TGFβ treatment induced the activation of P-SMAD2/3, SMAD4, P-ERK 1/2, P-P38, and P-JNK MAPK signaling pathways. PAI-1, CTGF, AP-1 and SP-1 promoter activity increased in response to TGFβ treatment. However, treatment with 6-BIO decreased the expression of proteins and signaling pathways associated with fibrosis in UUO model as well as in TGFβ-treated HK-2 and NRK49F cells. Moreover, 6-BIO treatment attenuated the expression of PAI-1 and CTGF as well as the promoter activities of AP-1 and SP-1, thereby regulating the SMAD and MAPK signaling pathways, and subsequently exerting anti-fibrotic effects on kidney cells.

B Cell Lymphoma 2: A Potential Therapeutic Target for Cancer Therapy

Defects in the apoptosis mechanism stimulate cancer cell growth and survival. B cell lymphoma 2 (Bcl-2) is an anti-apoptotic molecule that plays a central role in apoptosis. Bcl-2 is the founding constituent of the Bcl-2 protein family of apoptosis controllers, the primary apoptosis regulators linked with cancer. Bcl-2 has been identified as being over-expressed in several cancers. Bcl-2 is induced by protein kinases and several signaling molecules which stimulate cancer development. Identifying the important function played by Bcl-2 in cancer progression and development, and treatment made it a target related to therapy for multiple cancers. Among the various strategies that have been proposed to block Bcl-2, BH3-mimetics have appeared as a novel group of compounds thanks to their favorable effects on many cancers within several clinical settings. Because of the fundamental function of Bcl-2 in the regulation of apoptosis, the Bcl-2 protein is a potent target for the development of novel anti-tumor treatments. Bcl-2 inhibitors have been used against several cancers and provide a pre-clinical platform for testing novel therapeutic drugs. Clinical trials of multiple investigational agents targeting Bcl-2 are ongoing. This review discusses the role of Bcl-2 in cancer development; it could be exploited as a potential target for developing novel therapeutic strategies to combat various types of cancers. We further highlight the therapeutic activity of Bcl-2 inhibitors and their implications for the therapeutic management of cancer.

Identification of Potential Kinase Inhibitors within the PI3K/AKT Pathway of Leishmania Species

Leishmaniasis is a public health disease that requires the development of more effective treatments and the identification of novel molecular targets. Since blocking the PI3K/AKT pathway has been successfully studied as an effective anticancer strategy for decades, we examined whether the same approach would also be feasible in Leishmania due to their high amount and diverse set of annotated proteins. Here, we used a best reciprocal hits protocol to identify potential protein kinase homologues in an annotated human PI3K/AKT pathway. We calculated their ligandibility based on available bioactivity data of the reported homologues and modelled their 3D structures to estimate the druggability of their binding pockets. The models were used to run a virtual screening method with molecular docking. We found and studied five protein kinases in five different Leishmania species, which are AKT, CDK, AMPK, mTOR and GSK3 homologues from the studied pathways. The compounds found for different enzymes and species were analysed and suggested as starting point scaffolds for the design of inhibitors. We studied the kinases’ participation in protein–protein interaction networks, and the potential deleterious effects, if inhibited, were supported with the literature. In the case of Leishmania GSK3, an inhibitor of its human counterpart, prioritized by our method, was validated in vitro to test its anti-Leishmania activity and indirectly infer the presence of the enzyme in the parasite. The analysis contributes to improving the knowledge about the presence of similar signalling pathways in Leishmania, as well as the discovery of compounds acting against any of these kinases as potential molecular targets in the parasite.

Increased Expression of p-GSK3β Predicts Poor Survival in T -III/IV Stage OSCC Patients

BACKGROUND/AIM

Glycogen synthase kinase 3 beta (GSK3-β) acts either as a tumor suppressor or an oncogene in various human cancers. The present study aimed to investigate the expression and activity of p-GSK3-β (Ser9) in oral cancer patients.

MATERIALS AND METHODS

We investigated the levels of p-GSK3β in 152 oral cancer tissues by immunohistochemistry, and explored their prognostic impact.

RESULTS

To investigate the role of p-GSK3β (Ser9) in OSCC progression, we first analyzed the expression levels of protein p-GSK3β in normal and oral cancer tissues using immunohistochemical staining. p-GSK3β immunostaining was detected in 32 of 152 (21.1%) oral cancer specimens. High p-GSK3β expression was significantly associated with T (III/IV) stage. Kaplan-Meier survival analysis revealed that high levels of p-GSK3β were correlated with poor survival (p=0.001) in T stage (III/IV) OSCC patients. Multivariate analyses indicated that TN stage, AJCC tumor stage, tumor differentiation status and clinical therapy, but not p-GSK3β levels, were independent prognostic factors. Significant mortality risk was found in T stage (III/IV) oral cancer patients with high levels of p-GSK3β (p=0.0006).

CONCLUSION

GSK3β inactivation is a key event in oral cancer patients and targeting GSK3β might be valuable in treating oral cancer patients.

lncRNA UASR1 is overexpressed in oral squamous cell carcinoma and regulates cancer cell proliferation by regulating miR-375/JAK2 axis

Long non-coding RNAs (lncRNAs) have been confirmed to participate in cancer regulation, including oral squamous cell carcinoma (OSCC). The aim of the present study was to investigate the role of UASR1 in OSCC. The expression levels of UASR1, miR-375 and JAK2 were detected in OSCC tissues by reverse transcriptase quantitative PCR. The targets of UASR1 were predicted by IntaRNA. Colony formation and CCK-8 assays were conducted to estimate cell proliferation. Western blotting was used to detect the protein expression of JAK2. The results demonstrated that UASR1 was upregulated in OSCC tissues compared with non-tumor tissues, and the high level of UASR1 expression was associated with poor overall survival. UASR1 is predicted to interact with miR-375 and the interaction was confirmed by Dual-luciferase activity assay. However, overexpression of UASR1 and miR-375 did not affect the expression of each other. Instead, upregulation of JAK2, a target of miR-375, was observed after the overexpression of UASR1 in OSCC cells. Moreover, overexpression of UASR1 attenuated the inhibitory effects of miR-375 on the expression of JAK2 and cell proliferation. Therefore, UASR1 is overexpressed in OSCC and regulates cancer cell proliferation by regulating the miR-375/JAK2 axis.

The role of glycogen synthase kinase 3 (GSK3) in cancer with emphasis on ovarian cancer development and progression: A comprehensive review

Glycogen synthase kinase 3 (GSK3) is a monomeric serine-threonine kinase discovered in 1980 in a rat skeletal muscle. It has been involved in various cellular processes including embryogenesis, immune response, inflammation, apoptosis, autophagy, wound healing, neurodegeneration, and carcinogenesis. GSK3 exists in two different isoforms, GSK3α and GSK3β, both containing seven antiparallel beta-plates, a short linking part and an alpha helix, but coded by different genes and variously expressed in human tissues. In the current review, we comprehensively appraise the current literature on the role of GSK3 in various cancers with emphasis on ovarian carcinoma. Our findings indicate that the role of GSK3 in ovarian cancer development cannot be decisively determined as the currently available data support both prooncogenic and tumor-suppressive effects. Likewise, the clinical impact of GSK3 expression on ovarian cancer patients and its potential therapeutic implications are also limited. Further studies are needed to fully elucidate the pathophysiological and clinical implications of GSK3 activity in ovarian cancer.

mTOR-targeted cancer therapy: great target but disappointing clinical outcomes, why?

The mammalian target of rapamycin (mTOR) critically regulates several essential biological functions, such as cell growth, metabolism, survival, and immune response by forming two important complexes, namely, mTOR complex 1 (mTORC1) and complex 2 (mTORC2). mTOR signaling is often dysregulated in cancers and has been considered an attractive cancer therapeutic target. Great efforts have been made to develop efficacious mTOR inhibitors, particularly mTOR kinase inhibitors, which suppress mTORC1 and mTORC2; however, major success has not been achieved. With the strong scientific rationale, the intriguing question is why cancers are insensitive or not responsive to mTOR-targeted cancer therapy in clinics. Beyond early findings on induced activation of PI3K/Akt, MEK/ERK, and Mnk/eIF4E survival signaling pathways that compromise the efficacy of rapalog-based cancer therapy, recent findings on the essential role of GSK3 in mediating cancer cell response to mTOR inhibitors and mTORC1 inhibition-induced upregulation of PD-L1 in cancer cells may provide some explanations. These new findings may also offer us the opportunity to rationally utilize mTOR inhibitors in cancer therapy. Further elucidation of the biology of complicated mTOR networks may bring us the hope to develop effective therapeutic strategies with mTOR inhibitors against cancer.

Long non‑coding RNA MEG3 suppresses epithelial‑to‑mesenchymal transition by inhibiting the PSAT1‑dependent GSK‑3β/Snail signaling pathway in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the main subtype of esophageal cancer in China, and the prognosis of patients remains poor mainly due to the occurrence of lymph node and distant metastasis. The long non‑coding RNA (lncRNA) maternally expressed gene 3 (MEG3) has been shown to have tumor‑suppressive properties and to play an important role in epithelial‑to‑mesenchymal transition (EMT) in some solid tumors. However, whether MEG3 is involved in EMT in ESCC remains unclear. In the present study, the MEG3 expression level and its association with tumorigenesis were determined in 43 tumor tissues of patients with ESCC and in ESCC cells using reverse transcription‑quantitative PCR analysis. Gene microarray analysis was performed to detect differentially expressed genes (DEGs). Based on the functional annotation results, the effects of ectopic expression of MEG3 on cell growth, migration, invasion and EMT were assessed. MEG3 expression level was found to be markedly lower in tumor tissues and cells. Statistical analysis revealed that MEG3 expression was significantly negatively associated with lymph node metastasis and TNM stage in ESCC. Fluorescence in situ hybridization assay demonstrated that MEG3 was expressed mainly in the nucleus. Ectopic expression of MEG3 inhibited cell proliferation, migration, invasion and cell cycle progression in EC109 cells. Gene microarray results demonstrated that 177 genes were differentially expressed ≥2.0 fold in MEG3‑overexpressing cells, including 23 upregulated and 154 downregulated genes. Functional annotation revealed that the DEGs were mainly involved in amino acid biosynthetic process, mitogen‑activated protein kinase signaling, and serine and glycine metabolism. Further experiments indicated that the ectopic expression of MEG3 significantly suppressed cell proliferation, migration, invasion and EMT by downregulating phosphoserine aminotransferase 1 (PSAT1). In pathological tissues, PSAT1 and MEG3 were significantly negatively correlated, and high expression of PSAT1 predicted poor survival. Taken together, these results suggest that MEG3 may be a useful prognostic biomarker and may suppress EMT by inhibiting the PSAT1‑dependent glycogen synthase kinase‑3β/Snail signaling pathway in ESCC.

LDOC1 Suppresses Microbe-Induced Production of IL-1β in Human Normal and Cancerous Oral Cells through the PI3K/Akt/GSK-3β Axis

Simple Summary

Oral microbes often proliferate due to poor oral hygiene (POH). POH is associated with OSCC (oral squamous cell carcinoma). We investigated the role of LDOC1 in the production of IL-1β, an oncogenic proinflammatory cytokine in OSCC, induced by microorganisms in human oral cells. Candida albicans (CA) was detected in OSCC tissues. CA and the oral bacterium Fusobacterium nucleatum stimulate higher levels of IL-1β production in LDOC1-deficient OSCC cells than in LDOC1-expressing oral cells. CA SC5314 increased OSCC incidence in carcinogen-treated mice. Loss and gain of LDOC1 function resulted in increased and decreased, respectively, CA SC5314-induced IL-1β production. LDOC1 deficiency increased active pAkt^S473 upon SC5314 stimulation and inactive pGSK-3β^S9 phosphorylated by pAkt^S473. PI3K and Akt inhibitors and expression of constitutively active mutant GSK-3β^S9A reduced the SC5314-stimulated IL-1β production in LDOC1-deficient cells. These results indicate that the PI3K/Akt/pGSK-3β signaling contributes to LDOC1-mediated inhibition of microbe-induced IL-1β production, suggesting LDOC1 may determine the role of oral microbes in POH-associated OSCC.

Abstract

Poor oral hygiene (POH) is associated with oral squamous cell carcinoma (OSCC). Oral microbes often proliferate due to POH. Array data show that LDOC1 plays a role in immunity against pathogens. We investigated whether LDOC1 regulates the production of oral microbe-induced IL-1β, an oncogenic proinflammatory cytokine in OSCC. We demonstrated the presence of Candida albicans (CA) in 11.3% of OSCC tissues (n = 80). CA and the oral bacterium Fusobacterium nucleatum stimulate higher levels of IL-1β secretion by LDOC1-deficient OSCC cells than by LDOC1-expressing oral cells. CA SC5314 increased OSCC incidence in 4-NQO (a synthetic tobacco carcinogen) and arecoline-cotreated mice. Loss and gain of LDOC1 function significantly increased and decreased, respectively, CA SC5314-induced IL-1β production in oral and OSCC cell lines. Mechanistic studies showed that LDOC1 deficiency increased active phosphorylated Akt upon CA SC5314 stimulation and subsequent inhibitory phosphorylation of GSK-3β^S9 by activated Akt. PI3K and Akt inhibitors and expression of the constitutively active mutant GSK-3β^S9A significantly reduced the CA SC5314-stimulated IL-1β production in LDOC1-deficient cells. These results indicate that the PI3K/Akt/pGSK-3β signaling pathway contributes to LDOC1-mediated inhibition of oral microbe-induced IL-1β production, suggesting that LDOC1 may determine the pathogenic role of oral microbes in POH-associated OSCC.

Glycogen synthase kinase 3β in tumorigenesis and oncotherapy (Review)

Glycogen synthase kinase 3β (GSK 3β), a multifunctional serine and threonine kinase, plays a critical role in a variety of cellular activities, including signaling transduction, protein and glycogen metabolism, cell proliferation, cell differentiation, and apoptosis. Therefore, aberrant regulation of GSK 3β results in a broad range of human diseases, such as tumors, diabetes, inflammation and neurodegenerative diseases. Accumulating evidence has suggested that GSK 3β is correlated with tumorigenesis and progression. However, GSK 3β is controversial due to its bifacial roles of tumor suppression and activation. In addition, overexpression of GSK 3β is involved in tumor growth, whereas it contributes to the cell sensitivity to chemotherapy. However, the underlying regulatory mechanisms of GSK 3β in tumorigenesis remain obscure and require further in‑depth investigation. In this review, we comprehensively summarize the roles of GSK 3β in tumorigenesis and oncotherapy, and focus on its potentials as an available target in oncotherapy.

PP9, a steroidal saponin, induces G2/M arrest and apoptosis in human colorectal cancer cells by inhibiting the PI3K/Akt/GSK3β pathway

Colorectal cancer (CRC) represents one of the commonest malignancies around the world. PP9, a natural steroidal saponin, was firstly isolated from the rhizomes of Paris polyphylla var. latifolia. However, the therapeutic effects of PP9 on CRC and the underlying molecular mechanism remain undefined. Here, we demonstrated that treatment with PP9 time- and dose-dependently inhibited HT-29 and HCT116 cells without significantly inhibiting normal NCM460 cells. Furthermore, our results indicated that PP9 effectively induced G2/M phase arrest by upregulating p21 and suppressing cdc25C, Cyclin B1 and cdc2. Meanwhile, PP9 upregulated cleaved Caspase 3, cleaved Caspase 9 and cleaved PARP and Bax, while downregulating Bcl-2 to stimulate cell apoptosis. Mechanistically, PP9-suppressed PI3K/Akt/GSK3β signaling, while the PI3K inhibitor LY294002 augmented PP9-mediated apoptosis, G2/M arrest and effects on PI3K/Akt/GSK3β related proteins. Finally, we showed that PP9 (10 mg/kg) significantly reduced tumor growth in nude mouse CRC xenografts, more potently than 5-Fu (20 mg/kg). Jointly, these data firstly demonstrated that PP9 promotes G2/M arrest and apoptotic death in CRC cells through PI3K/Akt/GSK3β signaling suppression, suggesting that PP9 could be considered a new and promising candidate for CRC therapy.

Peroxiredoxin I deficiency increases pancreatic β‑cell apoptosis after streptozotocin stimulation via the AKT/GSK3β signaling pathway

Apoptosis of pancreatic β-cells is involved in the pathogenesis of type I and II diabetes. Peroxiredoxin I (Prx I) serves an important role in regulating cellular apoptosis; however, the role of Prx I in pancreatic β-cell apoptosis is not completely understood. In the present study, the role of peroxiredoxin 1 (Prx I) during streptozotocin (STZ)-induced apoptosis of pancreatic β-cells was investigated. The expression level of Prx I was decreased by STZ treatment in a time-dependent manner, and apoptosis of Prx I knockdown MIN6 cells was increased by STZ stimulation, compared with untransduced MIN6 cells. Furthermore, an intraperitoneal injection of STZ increased pancreatic islet damage in Prx I knockout mice, compared with wild-type and Prx II knockout mice. AKT and glycogen synthase kinase (GSK)-3β phosphorylation significantly decreased following Prx I knockdown in MIN6 cells. However, phosphorylated β-catenin and p65 levels significantly increased after STZ stimulation, compared with untransduced cells. The results of the present study indicate that deletion of Prx I mediated STZ-induced pancreatic β-cell death in vivo and in vitro by regulating the AKT/GSK-3β/β-catenin signaling pathway, as well as NF-κB signaling. These findings provide a theoretical basis for treatment of pancreatic damage.

E3 ligase ZFP91 inhibits Hepatocellular Carcinoma Metabolism Reprogramming by regulating PKM splicing

Rationale: Hepatocellular carcinoma (HCC) is one of the most lethal cancers, and few molecularly targeted anticancer therapies have been developed to treat it. Thus, the identification of new therapeutic targets is urgent. Metabolic reprogramming is an important hallmark of cancer. However, how ubiquitin ligases are involved in the regulation of cancer metabolism remains poorly understood. Methods: RT-PCR, western blot and IHC were used to determine ZFP91 expression. RNAi, cell proliferation, colony formation and transwell assays were used to determine the in vitro functions of ZFP91. Mouse xenograft models were used to study the in vivo effects of ZFP91. Co-IP together with mass spectrometry or western blot was utilized to investigate protein-protein interaction. Ubiquitination was analyzed using IP together with western blot. RNA splicing was assessed by using RT-PCR followed by restriction digestion. Lactate production and glucose uptake assays were used to analyze cancer metabolism. Results: We identified that an E3 ligase zinc finger protein 91 (ZFP91) suppressed HCC metabolic reprogramming, cell proliferation and metastasis in vitro and in vivo. Mechanistically, ZFP91 promoted the Lys48-linked ubiquitination of the oncoprotein hnRNP A1 at lysine 8 and proteasomal degradation, thereby inhibiting hnRNP A1-dependent PKM splicing, subsequently resulting in higher PKM1 isoform formation and lower PKM2 isoform formation and suppressing HCC glucose metabolism reprogramming, cell proliferation and metastasis. Moreover, HCC patients with lower levels of ZFP91 have poorer prognoses, and ZFP91 is an independent prognostic factor for patients with HCC. Conclusions: Our study identifies ZFP91 as a tumor suppressor of hepatocarcinogenesis and HCC metabolism reprogramming and proposes it as a novel prognostic biomarker and therapeutic target of HCC.

Positive Feedback Loop of SNAIL-IL-6 Mediates Myofibroblastic Differentiation Activity in Precancerous Oral Submucous Fibrosis

Oral submucosal fibrosis (OSF) is a premalignant disorder of the oral cavity, and areca nut chewing is known to be a major etiological factor that could induce epithelial to mesenchymal transition (EMT) and activate buccal mucosal fibroblasts (BMFs). However, this detailed mechanism is not fully understood. In this study, we showed that the upregulation of Snail in OSF samples and fibrotic BMFs (fBMFs) may result from constant irritation by arecoline, a major alkaloid of the areca nut. The elevation of Snail triggered myofibroblast transdifferentiation and was crucial to the persistent activation of fBMFs. Meanwhile, Snail increased the expression of numerous fibrosis factors (e.g., α-SMA and collagen I) as well as IL-6. Results from bioinformatics software and a luciferase-based reporter assay revealed that IL-6 was a direct target of Snail. Moreover, IL-6 in BMFs was found to further increase the expression of Snail and mediate Snail-induced myofibroblast activation. These findings suggested that there was a positive loop between Snail and IL-6 to regulate the areca nut-associated myofibroblast transdifferentiation, which implied that the blockage of Snail may serve as a favorable therapeutic strategy for OSF treatment.

Alterations and molecular targeting of the GSK-3 regulator, PI3K, in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is a highly morbid, genetically unstable disease derived from the mucoepithelium of the upper aerodigestive tract. Recent characterization of this disease has implicated the PI3K-Akt-mTOR pathway as one of the most frequently dysregulated pathways. As such, there are several classes of PI3K inhibitors currently undergoing clinical trials. In this article, we review the PI3K pathway, mutations of this pathway in HNSCC, drugs that target PI3K, the impact of these agents on the PI3K and GSK-3 signaling axes, ongoing clinical trials evaluating PI3K inhibitors, and the challenges of using these drugs in the clinic. This article is part of a Special Issue entitled: GSK-3 and related kinases in cancer, neurological and other disorders edited by James McCubrey, Agnieszka Gizak and Dariusz Rakus.

Roles of the PI3K/AKT/mTOR signalling pathways in neurodegenerative diseases and tumours

The PI3 K/AKT/mTOR signalling pathway plays an important role in the regulation of signal transduction and biological processes such as cell proliferation, apoptosis, metabolism and angiogenesis. Compared with those of other signalling pathways, the components of the PI3K/AKT/mTOR signalling pathway are complicated. The regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway are important in many human diseases, including ischaemic brain injury, neurodegenerative diseases, and tumours. PI3K/AKT/mTOR signalling pathway inhibitors include single-component and dual inhibitors. Numerous PI3K inhibitors have exhibited good results in preclinical studies, and some have been clinically tested in haematologic malignancies and solid tumours. In this review, we briefly summarize the results of research on the PI3K/AKT/mTOR pathway and discuss the structural composition, activation, communication processes, regulatory mechanisms and biological functions of the PI3K/AKT/mTOR signalling pathway in the pathogenesis of neurodegenerative diseases and tumours.

The cytosolic isoform of glutaredoxin 2 promotes cell migration and invasion

BACKROUND

Cytosolic glutaredoxin 2 (Grx2c) controls axonal outgrowth and is specifically induced in many cancer cell lines. We thus hypothesized that Grx2c promotes cell motility and invasiveness.

METHODS

We characterized the impact of Grx2c expression in cell culture models. We combined stable isotope labeling, phosphopeptide enrichment, and high-accuracy mass spectrometry to characterize the underlying mechanisms.

RESULTS

The most prominent associations were found with actin dynamics, cellular adhesion, and receptor-mediated signal transduction, processes that are crucial for cell motility. For instance, collapsin response mediator protein 2, a protein involved in the regulation of cytoskeletal dynamics, is regulated by Grx2c through a redox switch that controls the phosphorylation state of the protein as well. Cell lines expressing Grx2c showed dramatic alterations in morphology. These cells migrated two-fold faster and gained the ability to infiltrate a collagen matrix.

CONCLUSIONS

The expression of Grx2c promotes cell migration, and may negatively correlate with cancer-specific survival.

GENERAL SIGNIFICANCE

Our results imply critical roles of Grx2c in cytoskeletal dynamics, cell adhesion, and cancer cell invasiveness.

Dietary AGEs involvement in colonic inflammation and cancer: insights from an in vitro enterocyte model

The number of colon cancer cases is increasing worldwide, and type II diabetes patients have an increased risk of developing colon cancer. Diet-borne advanced glycation end-products (AGEs) may promote neoplastic transformation; however, the mechanisms involved remain elusive. The present study helped to define the relationship between dietary AGEs and cancer progression. C2BBe1 adenocarcinoma enterocytes were exposed to 200 µg/mL glycated casein (AGEs-Csn) for up to 24 h. AGEs-Csn exposure resulted in increased cell proliferation, maladaptative changes in SOD and CAT activity and moderate levels of hydrogen peroxide (H₂O₂) intracellular accumulation. AGEs-Csn activated pro-survival and proliferation signalling, such as the phosphorylation of mTOR (Ser2448) and Akt (Ser473). GSK-3β phosphorylation also increased, potentially inducing extracellular matrix remodelling and thus enabling metastasis. Moreover, AGEs-Csn induced MMP-1, -3, -7, -9 and -10 expression and activated MMP-2 and MMP-9, which are regulators of the extracellular matrix and cytokine functions. AGEs-Csn induced inflammatory responses that included extracellular IL-1β at 6 h; time-dependent increases in IL-8; RAGE and NF-κB p65 upregulation; and IκB inhibition. Co-treatment with anti-RAGE or anti-TNF-α blocking antibodies and AGEs-Csn partially counteracted these changes; however, IL-8, MMP-1 and -10 expression and MMP-9 activation were difficult to prevent. AGEs-Csn perpetuated signalling that led to cell proliferation and matrix remodelling, strengthening the link between AGEs and colorectal cancer aggressiveness.

Inhibition of TPA‑induced metastatic potential by morin hydrate in MCF‑7 human breast cancer cells via the Akt/GSK‑3β/c‑Fos signaling pathway

Plant flavonoid 2',3,4',5,7‑pentahydroxyflavone (morin hydrate), isolated from the family Moraceae (Morus alba L.), is known to have anti‑inflammatory and anticancer effects. However, its pharmaceutical effects on metastasis have not been fully elucidated to date. Therefore, the current study investigated the effects of morin hydrate on cancer metastasis in MCF‑7 human breast cancer cells. The results showed that morin hydrate suppressed 12‑O‑tetradecanoylphorbol‑13‑acetate (TPA)‑induced cell migration and invasion via the inhibition of matrix metalloproteinase (MMP)‑9 activity. Furthermore, gene expression level of MMP‑9, MMP‑7, urokinase plasminogen activator (uPA), uPA receptor (uPAR) and fibronectin were significantly decreased by morin hydrate treatment. Morin hydrate inhibited the phosphorylation of Akt and glycogen synthase kinase (GSK)‑3β, and downregulated the expression of an activator protein‑1 subunit c‑Fos. In addition, the GSK‑3β phosphorylation and c‑Fos expression were suppressed by PI3K/Akt pathway inhibitors, LY294002 and wortmannin. Taken together, these results demonstrated that morin hydrate reduced the metastatic potential in TPA‑treated MCF‑7 human breast cancer cells via the inhibition of MMPs, uPA and uPAR, and the underlying Akt/GSK‑3β/c‑Fos pathway. Therefore, the present investigation suggested that morin hydrate may be a natural substance with a preventive potential for metastasis in breast cancer cells.

Glycogen Synthase Kinase-3 Inhibition Sensitizes Pancreatic Cancer Cells to Chemotherapy by Abrogating the TopBP1/ATR-Mediated DNA Damage Response

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is a predominantly fatal common malignancy with inadequate treatment options. Glycogen synthase kinase 3β (GSK-3β) is an emerging target in human malignancies including PDAC.Experimental Design: Pancreatic cancer cell lines and patient-derived xenografts were treated with a novel GSK-3 inhibitor 9-ING-41 alone or in combination with chemotherapy. Activation of the DNA damage response pathway and S-phase arrest induced by gemcitabine were assessed in pancreatic tumor cells with pharmacologic inhibition or siRNA depletion of GSK-3 kinases by immunoblotting, flow cytometry, and immunofluorescence.

RESULTS

9-ING-41 treatment significantly increased pancreatic tumor cell killing when combined with chemotherapy. Inhibition of GSK-3 by 9-ING-41 prevented gemcitabine-induced S-phase arrest suggesting an impact on the ATR-mediated DNA damage response. Both 9-ING-41 and siRNA depletion of GSK-3 kinases impaired the activation of ATR leading to the phosphorylation and activation of Chk1. Mechanistically, depletion or knockdown of GSK-3 kinases resulted in the degradation of the ATR-interacting protein TopBP1, thus limiting the activation of ATR in response to single-strand DNA damage.

CONCLUSIONS

These data identify a previously unknown role for GSK-3 kinases in the regulation of the TopBP1/ATR/Chk1 DNA damage response pathway. The data also support the inclusion of patients with PDAC in clinical studies of 9-ING-41 alone and in combination with gemcitabine.

Secreted amphiregulin promotes vincristine resistance in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. Despite advances in surgery, radiotherapy and chemotherapy, the overall 5‑year survival rate of patients with OSCC has not significantly improved. In addition, the prognosis of patients with advanced‑stage OSCC remains poor. Therefore, it is necessary to develop novel therapeutic modalities. Vincristine (VCR), a naturally occurring vinca alkaloid, is a classical microtubule‑destabilizing agent and is widely used in the treatment of a number of cancers. Despite the proven antitumor benefits of VCR treatment, one of the major reasons for the failure of treatment is drug resistance. Changes in the tumor microenvironment are responsible for cross‑talk between cells, which may facilitate drug resistance in cancers; secreted proteins may promote communication between cancer cells to induce the development of resistance. To identify the secreted proteins involved in VCR resistance, conditioned media was obtained, and an antibody array was conducted to screen a comprehensive secretion profile between VCR‑resistant (SAS‑VCR) and parental (SAS) OSCC cell lines. The results showed that amphiregulin (AREG) was highly expressed and secreted in SAS‑VCR cells. Pretreatment with exogenous recombinant AREG markedly increased drug resistance against VCR in OSCC cells, as assessed by an MTT assay. Colony formation, MTT and western blot assays were performed to investigate the effects of AREG knockdown on VCR sensitivity. The results indicated that AREG expression can regulate VCR resistance in OSCC cells; overexpression of AREG increased VCR resistance in parental cells, whereas AREG knockdown decreased the VCR resistance of resistant cells. In addition, it was also demonstrated that the glycogen synthase kinase‑3β pathway may be involved in AREG‑induced VCR resistance. These findings may provide rationale to combine VCR with blockade of AREG‑related pathways for the effective treatment of OSCC.

mTORC2 Suppresses GSK3-Dependent Snail Degradation to Positively Regulate Cancer Cell Invasion and Metastasis

mTOR complex 1 (mTORC1) positively regulates cell invasion and metastasis by enhancing translation of Snail. A connection between mTOR complex 2 (mTORC2) and cell invasion and metastasis has also been suggested, yet the underlying biology or mechanism is largely unknown and thus is the focus of this study. Inhibition of mTOR with both mTOR inhibitors and knockdown of key components of mTORC, including rictor, Sin1, and raptor, decreased Snail protein levels. Inhibition of mTOR enhanced the rate of Snail degradation, which could be rescued by inhibition of the proteasome. Critically, inhibition of mTORC2 (by knocking down rictor) but not mTORC1 (by knocking down raptor) enhanced Snail degradation. Therefore, only mTORC2 inhibition induces Snail proteasomal degradation, resulting in eventual Snail reduction. Interestingly, inhibition of GSK3 but not SCF/β-TrCP rescued the Snail reduction induced by mTOR inhibitors, suggesting GSK3-dependent, but SCF/β-TrCP-independent proteasomal degradation of Snail. Accordingly, mTOR inhibitors elevated E-cadherin levels and suppressed cancer cell migration and invasion in vitro and metastasis in vivo. Collectively, this study reveals that mTORC2 positively regulates Snail stability to control cell invasion and metastasis. SIGNIFICANCE: These findings delineate a new regulation mechanism of Snail, an important master regulator of epithelial-mesenchymal transition and invasion in cancers.

Different expression of GSK3β and pS9GSK3β depending on phenotype of cervical cancer: possible association of GSK3β with squamous cell carcinoma and pS9GSK3β with adenocarcinoma

Objective

This study aimed to analyze the expression pattern of glycogen synthase kinase 3β (GSK3β) and its phosphorylated forms, GSK3β phosphorylated at Ser9 (pS9GSK3β), and GSK3β phosphorylated at Tyr216 (pY216GSK3β), in cervical squamous cell carcinoma (SCC) and adenocarcinoma (AC).

Methods

We performed immunohistochemical staining for GSK3β, pS9GSK3β, and pY216GSK3β in 64 SCC and 20 AC cases and compared their expression patterns between the 2 tumor types.

Results

Increased GSK3β and pS9GSK3β expression but decreased pY216GSK3β expression compared with that in the normal cervix were observed in both SCC and AC specimens. Specifically, the levels of GSK3β and pS9GSK3β were significantly increased in SCC and AC, respectively. GSK3β was localized in the nucleus and/or cytoplasm of SCC and AC cells. However, pS9GSK3β was predominantly localized in the membrane of AC cells, whereas it was present in the nucleus and/or cytoplasm of SCC cells.

Conclusion

The results suggest that the phosphorylation status of GSK3β changes during cervical cancer development and the different expression levels and patterns of GSK3β and pS9GSK3β are associated with the specific histologic phenotype of cervical cancer.

Exposure to nicotine-derived nitrosamine ketone and arecoline synergistically facilitates tumor aggressiveness via overexpression of epidermal growth factor receptor and its downstream signaling in head and neck squamous cell carcinoma

Long-term nicotine-derived nitrosamine ketone (NNK) and arecoline exposure promotes carcinogenesis and head and neck squamous cell carcinoma (HNSCC) progression, although most associated data on the two were analyzed individually. The molecular mechanisms underlying tumor progression associated with the synergistic effects of NNK and arecoline remain unclear. We treated SCC-25 and FaDu cells with NNK and arecoline (separately or in combination) for 3 months. Comparative analysis was performed to investigate the mechanism underlying the acquisition of properties related to tumor promotion, including stemness, anti-apoptosis, and resistance to HNSCC therapeutics. Long-term exposure to NNK and arecoline resulted in an increase in cancer stem cell properties, anti-apoptosis, and the resistance to cisplatin in HNSCC. We detected abundant epidermal growth factor receptor (EGFR) expression in HNSCC cells after combined treatment with NNK and arecoline. EGFR was pivotal in inducing tumor promotion and anti-apoptosis in cancer cells by inducing pAKT and NFκB. Combined treatment with NNK and arecoline synergistically facilitated tumor aggressiveness via EGFR–AKT signaling. Targeting EGFR–AKT signaling may be a feasible strategy for treating HNSCC.

Polyubiquitination inhibition of estrogen receptor alpha and its implications in breast cancer

Estrogen receptor alpha (ERα) is detected in more than 70% of the cases of breast cancer. Nuclear activity of ERα, a transcriptional regulator, is linked to the development of mammary tumors, whereas the extranuclear activity of ERα is related to endocrine therapy resistance. ERα polyubiquitination is induced by the estradiol hormone, and also by selective estrogen receptor degraders, resulting in ERα degradation via the ubiquitin proteasome system. Moreover, polyubiquitination is related to the ERα transcription cycle, and some E3-ubiquitin ligases also function as coactivators for ERα. Several studies have demonstrated that ERα polyubiquitination is inhibited by multiple mechanisms that include posttranslational modifications, interactions with coregulators, and formation of specific protein complexes with ERα. These events are responsible for an increase in ERα protein levels and deregulation of its signaling in breast cancers. Thus, ERα polyubiquitination inhibition may be a key factor in the progression of breast cancer and resistance to endocrine therapy.

Licochalcone D directly targets JAK2 to induced apoptosis in human oral squamous cell carcinoma

Licochalcone (LC) families have been reported to have a wide range of biological function such as antioxidant, antibacterial, antiviral, and anticancer effects. Although various beneficial effects of LCD were revealed, its anticancer effect in human oral squamous cancer has not been identified. To examine the signaling pathway of LCD's anticancer effect, we determined whether LCD has physical interaction with Janus kinase (JAK2)/signal transducer and activator of transcription-3 (STAT3) signaling, which is critical in promoting cancer cell survival and proliferation. Our results demonstrated that LCD inhibited the kinase activity of JAK2, soft agar colony formation, and the proliferation of HN22 and HSC4 cells. LCD also induced mitochondrial apoptotic events such as altered mitochondrial membrane potential and reactive oxygen species production. LCD increased the expression of apoptosis-associated proteins in oral squamous cell carcinoma (OSCC) cells. Finally, the xenograft study showed that LCD significantly inhibited HN22 tumor growth. Immunohistochemical data supported that LCD suppressed p-JAK2 and p-STAT3 expression and induced cleaved-caspase-3 expression. These results indicate that the anticancer effect of LCD is due to the direct targeting of JAK2 kinase. Therefore, LCD can be used for therapeutic application against OSCC.

Potential biomarkers and therapeutic targets in cervical cancer: Insights from the meta-analysis of transcriptomics data within network biomedicine perspective

The malignant neoplasm of the cervix, cervical cancer, has effects on the reproductive tract. Although infection with oncogenic human papillomavirus is essential for cervical cancer development, it alone is insufficient to explain the development of cervical cancer. Therefore, other risk factors such as host genetic factors should be identified, and their importance in cervical cancer induction should be determined. Although gene expression profiling studies in the last decade have made significant molecular findings about cervical cancer, adequate screening and effective treatment strategies have yet to be achieved. In the current study, meta-analysis was performed on cervical cancer-associated transcriptome data and reporter biomolecules were identified at RNA (mRNA, miRNA), protein (receptor, transcription factor, etc.), and metabolite levels by the integration of gene expression profiles with genome-scale biomolecular networks. This approach revealed already-known biomarkers, tumor suppressors and oncogenes in cervical cancer as well as various receptors (e.g. ephrin receptors EPHA4, EPHA5, and EPHB2; endothelin receptors EDNRA and EDNRB; nuclear receptors NCOA3, NR2C1, and NR2C2), miRNAs (e.g., miR-192-5p, miR-193b-3p, and miR-215-5p), transcription factors (particularly E2F4, ETS1, and CUTL1), other proteins (e.g., KAT2B, PARP1, CDK1, GSK3B, WNK1, and CRYAB), and metabolites (particularly, arachidonic acids) as novel biomarker candidates and potential therapeutic targets. The differential expression profiles of all reporter biomolecules were cross-validated in independent RNA-Seq and miRNA-Seq datasets, and the prognostic power of several reporter biomolecules, including KAT2B, PCNA, CD86, miR-192-5p and miR-215-5p was also demonstrated. In this study, we reported valuable data for further experimental and clinical efforts, because the proposed biomolecules have significant potential as systems biomarkers for screening or therapeutic purposes in cervical carcinoma.

Identification of two potential glycogen synthase kinase 3β inhibitors for the treatment of osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor among adolescents worldwide with high mortality rate. Glycogen synthase kinase 3β (GSK3β) is a serine/threonine kinase and is considered as a validated target in osteosarcoma therapy. Therefore, the study of GSK3β inhibitors is one of the most popular fields in anti-osteosarcoma drug development. Here, the tools of bioinformatics were used to screen novel effective inhibitors of GSK3β from ZINC Drug Database. The molecular docking, molecular dynamic simulations, MM/GBSA, and energy decomposition analysis were performed to identify the inhibitors. Finally, ZINC08383479 and ZINC08441251 were selected as potential GSK3β inhibitors. These two inhibitors were evaluated by GSK3β kinase inhibition assay in vitro. The inhibition of cell proliferation was tested in osteosarcoma cell lines U2OS and MG63 in vitro. The result showed that ZINC08383479 and ZINC08441251 had high inhibition activity against GSK3β. We found that CHIR99021 (a known GSK3β inhibitor), ZINC08383479, and ZINC08441251 had significant inhibition activity in U2OS cells and MG63 cells. These findings may provide new ideas for the design of more potent GSK3β inhibitors and therapeutic targets for osteosarcoma.

Pathologic significance of AKT, mTOR, and GSK3β proteins in oral squamous cell carcinoma-affected patients

Phosphatidylinositol-3-kinases are kinases that lead to AKT phosphorylation and thus mTOR and GSK3β activation. These proteins are linked to tumorigenesis, but their roles in driving cervical lymph node (CLN) metastasis of oral squamous cell carcinoma (OSCC) cells are unknown. This study aimed to investigate the role of AKT, mTOR, and GSK3β proteins in the occurrence of CLN metastasis in OSCC patients. Ninety and 18 paraffin-embedded OSCC and oral mucosa samples were included, respectively. We divided our OSCC patients into non-metastasizing (PNM) and metastasizing (PM) groups, and the expression of total AKT, pAKT1^Thr308, pAKT^Ser473, GSK3β, pGSK3β^Ser9, and pmTOR^Ser2448 was analyzed by immunohistochemistry. The mean expression of GSK3β, pGSK3β^Ser9, total AKT, and pmTOR²⁴⁴⁸ was always higher in the OSCC tissues than that in the controls. A positive correlation was also found among these proteins. Total AKT, pmTOR^Ser2448, and pGSK3β^Ser9 expression was significantly higher in the PNM and PM groups than that in the control group. However, only GSK3β expression was significantly higher in the PM group compared with the PNM group. High expression levels of GSK3β and pGSK3β^Ser9 were significantly associated with CLN metastasis, but only GSK3β remained an independent predictor of CLN metastasis. pGSK3β^Ser9 and CLN metastasis were associated with a poor prognosis, but only the latter remained an independent prognostic parameter. Kaplan-Meier survival curves showed that pGSK3β^Ser9 and CLN metastasis were significantly related to reduced survival rates. These results suggest that AKT and mTOR proteins are involved in OSCC biology and that GSK3β itself may drive CLN metastatic spread of OSCC cells.

Proteomics-based investigation of multiple stages of OSCC development indicates that the inhibition of Trx-1 delays oral malignant transformation

The majority of cases of oral squamous cell carcinoma (OSCC) develop from oral potentially malignant disorders, which have been confirmed to be involved in chronic oxidative stimulation. However, no effective treatment approaches have been used to prevent the development of dysplasia into cancerous lesions thus far. In the present study, a well-established OSCC model was used to detect proteomics profiles at different stages during oral malignant transformation. Of the 15 proteins that were found to be upregulated in both the dysplasia and carcinoma stages, the oxidative stress-associated proteins, thioredoxin-1 (Trx-1), glutaredoxin-1 and peroxiredoxin-2 were note as the proteins with significant changes in expression Trx-1 was identified to be the most significantly upregulated protein in the precancerous stage. Validation experiments confirmed that Trx-1 was overex-pressed both in dysplasia and cancerous tissue samples, and the inhibition of Trx-1 was able to promote the apoptosis of OSCC cells under hypoxic conditions. Furthermore, the experimental application of a Trx-1-specific inhibitory agent in an animal model led to a lower cancerization rate and a delay in tumor formation. The possible mechanisms were associated with the increased apoptosis via a reactive oxygen species (ROS)-dependent pathway. Taken together, our findings indicate that Trx-1 may be an important target for delaying oral malignant transformation, which provides a novel therapeutic strategy for the prevention and treatment of OSCC.

Human Primary Epithelial Cells Acquire an Epithelial-Mesenchymal-Transition Phenotype during Long-Term Infection by the Oral Opportunistic Pathogen, Porphyromonas gingivalis

Porphyromonas gingivalis is a host-adapted oral pathogen associated with chronic periodontitis that successfully survives and persists in the oral epithelium. Recent studies have positively correlated periodontitis with increased risk and severity of oral squamous cell carcinoma (OSCC). Intriguingly, the presence of P. gingivalis enhances tumorigenic properties independently of periodontitis and has therefore been proposed as a potential etiological agent for OSCC. However, the initial host molecular changes induced by P. gingivalis infection which promote predisposition to cancerous transformation through EMT (epithelial-mesenchymal-transition), has never been studied in human primary cells which more closely mimic the physiological state of cells in vivo. In this study, we examine for the first time in primary oral epithelial cells (OECs) the expression and activation of key EMT mediators during long-term P. gingivalis infection in vitro. We examined the inactive phosphorylated state of glycogen synthase kinase-3 beta (p-GSK3β) over 120 h P. gingivalis infection and found p-GSK3β, an important EMT regulator, significantly increases over the course of infection (p < 0.01). Furthermore, we examined the expression of EMT-associated transcription factors, Slug, Snail, and Zeb1 and found significant increases (p < 0.01) over long-term P. gingivalis infection in protein and mRNA expression. Additionally, the protein expression of mesenchymal intermediate filament, Vimentin, was substantially increased over 120 h of P. gingivalis infection. Analysis of adhesion molecule E-cadherin showed a significant decrease (p < 0.05) in expression and a loss of membrane localization along with β-catenin in OECs. Matrix metalloproteinases (MMPs) 2, 7, and 9 are all markedly increased with long-term P. gingivalis infection. Finally, migration of P. gingivalis infected cells was evaluated using scratch assay in which primary OEC monolayers were wounded and treated with proliferation inhibitor, Mitomycin C. The cellular movement was determined by microscopy. Results displayed P. gingivalis infection promoted cell migration which was slightly enhanced by co-infection with Fusobacterium nucleatum, another oral opportunistic pathogen. Therefore, this study demonstrates human primary OECs acquire initial molecular/cellular changes that are consistent with EMT induction during long-term infection by P. gingivalis and provides a critically novel framework for future mechanistic studies.

Glycogen synthase kinase-3β mediated regulation of matrix metalloproteinase-9 and its involvement in oral squamous cell carcinoma progression and invasion

PURPOSE

Oral squamous cell carcinoma (OSCC)-related deaths mainly result from invasion of the tumor cells into local cervical lymph nodes. It has been reported that progressive basement membrane loss promotes the metastatic and invasive capacities of OSCCs. Matrix metalloproteinase-9 (MMP-9) is known to play a central role in tumor progression and invasion. However, the role of MMP-9 in OSCC invasion has so far remained paradoxical and little is known about its regulation. Here, we aimed to assess MMP-9 expression regulation and its activation by glycogen synthase kinase-3β during human OSCC progression and invasion.

METHODS

In the present study, 178 human OSCC samples, including 118 fresh samples (18 adjacent normal, 42 noninvasive and 58 invasive tumor samples) and 60 archival human tissue microarray (TMA) tongue cancer samples, were included. mRNA expression, protein expression, MMP-9/-2 activity, protein-protein interaction and Snail, c-Myc, β-catenin and TIMP1 expression were assessed using RT-PCR, immunohistochemistry, Western blotting, co-immunoprecipitation and gelatin zymography analyses, respectively. Wnt5a and LPA mediated MMP-9 regulation was assessed in OCSCC-derived SCC-9 cells exogenously expressing GSK3β (WT) or non phosphoryable GSK3β (S9A).

RESULTS

We observed a progressive up-regulation/activation of MMP-9 at various stages of oral tumor progression/invasion. Positive correlations were observed between MMP-9 and c-Myc expression, MMP-9 and MMP-2 activity, MMP-9 and TIMP1 expression and MMP-9 activity and TIMP1-MMP-9 interaction. In contrast, a negative correlation between phosphorylated β-catenin and MMP-9 expression was observed. Conversely, we found that in oral tongue SCC MMP-9 expression was positively correlated with inactivation of GSK3 signaling. Finally, we found that Wnt5a and LPA mediated increased MMP-9 and decreased GSK3β activities in tongue SCC-derived SCC-9 cells. MMP-9 regulation by GSK3β was confirmed by using phosphoryable/regulatory GSK3β (WT construct) and not by non-phosphoryable GSK3β (S9A construct).

CONCLUSIONS

Collectively, our results show that MMP-9 overexpression and activation are important events occurring during OSCC progression/invasion and that this overexpression/activation is regulated by c-Myc, active MMP-2 and inactive GSK3β mediated pathways.

Glycogen synthase kinase-3β ablation limits pancreatitis-induced acinar-to-ductal metaplasia

Acinar-to-ductal metaplasia (ADM) is a reversible epithelial transdifferentiation process that occurs in the pancreas in response to acute inflammation. ADM can rapidly progress towards pre-malignant pancreatic intraepithelial neoplasia (PanIN) lesions in the presence of mutant KRas and ultimately pancreatic adenocarcinoma (PDAC). In the present work, we elucidate the role and related mechanism of glycogen synthase kinase-3beta (GSK-3β) in ADM development using in vitro 3D cultures and genetically engineered mouse models. We show that GSK-3β promotes TGF-α-induced ADM in 3D cultured primary acinar cells, whereas deletion of GSK-3β attenuates caerulein-induced ADM formation and PanIN progression in Kras^G12D transgenic mice. Furthermore, we demonstrate that GSK-3β ablation influences ADM formation and PanIN progression by suppressing oncogenic KRas-driven cell proliferation. Mechanistically, we show that GSK-3β regulates proliferation by increasing the activation of S6 kinase. Taken together, these results indicate that GSK-3β participates in early pancreatitis-induced ADM and thus could be a target for the treatment of chronic pancreatitis and the prevention of PDAC progression. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Inhibition of glycogen synthase kinase 3 beta (GSK3β) suppresses the progression of esophageal squamous cell carcinoma by modifying STAT3 activity

Although GSK3β has been reported to have contrasting effects on the progression of different tumors, it's possible functions in esophageal squamous cell carcinoma (ESCC) and the related molecular mechanisms remain unknown. Here, we investigated the expression, function, and molecular mechanism of GSK3β in the development of ESCC in vitro and in vivo. Though the expression of total GSK3β was significantly increased, the phosphorylated (inactivated) form of GSK3β (Ser9) was concurrently decreased in the cancerous tissues of patients with ESCC compared with controls, suggesting that GSK3β activity was enhanced in cancerous tissues. Further pathological data analysis revealed that higher GSK3β expression was associated with poorer differentiation, higher metastasis rates, and worse prognosis of ESCC. These results were confirmed in different ESCC cell lines using a pharmacological inhibitor and specific siRNA to block GSK3β. Using a cancer phospho-antibody array, we found that STAT3 is a target of GSK3β. GSK3 inhibition reduced STAT3 phosphorylation, and overexpression of constitutively active GSK3β had the opposite effect. Moreover, STAT3 inhibition mimicked the effects of GSK3β inhibition on ESCC cell migration and viability, while overexpression of a plasmid encoding mutant STAT3 (Y705F) abrogated these effects, and these results were further substantiated by clinicopathological data. In addition, a GSK3 inhibitor (LiCl) and/or STAT3 inhibitor (WP-1066) efficiently suppressed the growth of ESCC cells in a xenograft tumor model. Altogether, these results reveal that higher GSK3β expression promotes ESCC progression through STAT3 in vitro and in vivo, and GSK3β-STAT3 signaling could be a potential therapeutic target for ESCC treatment.

Inhibitory Effect of 1,8-Cineol on β-Catenin Regulation, WNT11 Expression, and Cellular Progression in HNSCC

OBJECTIVES

Head and neck squamous cell carcinoma (HNSCC) is one of the most common tumors worldwide. The high mortality rates have not changed during the last three decades, and thus there is an enormous need for innovative therapy approaches. Several recent studies suggest an important role of the Wnt/β-catenin signaling pathway in the tumorigenesis of HNSCC. We analyzed the effect of the monoterpene oxide 1,8-cineol on the regulation of the Wnt/β-catenin signaling pathway and the cellular progression of different HNSCC cell lines.

METHODS

Permanent HNSCC cell lines were exposed to varying concentrations and times of 1,8-cineol. Regulation and activity profiles of the Wnt/β-catenin signaling cascade were analyzed using Western hybridization experiments, MTT assays, real-time PCR-based epithelial to mesenchymal transition array, and immunohistochemistry.

RESULTS

Exposure of different cell lines to 1,8-cineol treatment resulted in a dose-dependent inhibition of proliferation and a decreased activity of the WNT/β-catenin pathway. We can show the inhibition of glycogen synthase kinase 3 (GSK-3)α/β (Ser-9/21) as well as a corresponding decreased endolysosomal localization, leading to a decreased β-catenin activity. Furthermore, we can show that exposure to cineol functionally results in a reduced expression of WNT11.

CONCLUSION

In this work, we demonstrate for the first time that 1,8-cineol acts as an inhibitor of the Wnt/β-catenin activity in HNSCC via a decreased inhibition of GSK-3, which lead to reduced levels of WNT11 and a dose-dependent decrease of the cellular progression. Our data represent a new mechanism of 1,8-cineol activity, which may lead to novel molecular targets and treatment approaches of this natural drug.

The elevated activation of NFκB and AP-1 is correlated with differential regulation of Bcl-2 and associated with oral squamous cell carcinoma progression and resistance

OBJECTIVES

Oral cancer is the sixth most common cancer in the world. Failure of chemoradiation therapy is a major concern for treating oral cancer patients. The objective of this study is to determine the B cell lymphoma-2 (bcl-2) expression and its regulation by nuclear factor κB (NFκB) and activator protein 1 (AP-1) in oral cancer progression and chemoradiation resistance.

MATERIALS AND METHODS

In the present study, a total of 123 (n = 123) human samples were included. Briefly, 64 fresh samples were from adjacent normal (AN), primary oral tumors without treatment (PT), and tumors with resistance to chemoradiation therapy with local recurrence (RCRT). Fifty-nine samples were human tongue cancers and normal samples (TMA). Messenger RNA (mRNA) expression levels of bcl-2 and protein levels of bcl-2, NFκB, AP-1, and inactive GSK3α/β were measured by semiquantitative RT-PCR, immunohistochemistry, Western blot, and ChIP analysis.

RESULTS

Increased bcl-2 expression was observed in PT compared to AN. The RCRT tumors showed maximum expression of bcl-2 mRNA and protein over the PT and AN groups. Bcl-2 protein and mRNA expression were positively correlated with NFκB and AP-1 expression. AP-1 expression was strongly correlated with bcl-2 in the RCRT group of tumors. Further, inactive GSK3α/β showed a positive trend with bcl-2 expression in oral tongue cancer specimens.

CONCLUSION

Collectively, our results demonstrated cumulative effect of AP-1 and NFĸB for bcl-2 gene regulation in overall PT progression and chemoradiation resistance. The study provides evidence of increased bcl-2 mRNA/protein fueled by NFĸB in PT and AP-1 in RCRT. These regulations of bcl-2 by NFκB and AP-1 are important in OSCC progression and chemoradiation resistance.

Estrogen and ERα enhanced β-catenin degradation and suppressed its downstream target genes to block the metastatic function of HA22T hepatocellular carcinoma cells via modulating GSK-3β and β-TrCP expression

In our previous experiments, we found β-catenin was highly expressed in the tumor area with high invasive ability and poor prognosis. In this study, we have examined the mechanism by which ERα regulates β-catenin expression as well as the metastasis ability of hepatocellular cancer HA22T cells. To identify whether the anticancer effect of estrogen and ERα is mediated through suppression of β-catenin expression, we co-transfected pCMV-β-catenin and ERα into HA22T cells, and determined the cell motility by wound healing, invasion, and migration assays. Results showed that estrogen and/or ERα inhibited β-catenin gene expression and repressed HA22T cell motility demonstrated that similar data was observed in cells expressing the ERα stable clone. Moreover, we examined the protein-protein interaction between ERα and β-catenin by immunostain, co-immunoprecipitation, and Western blotting. E2 enhanced the binding of ERα with β-catenin and then triggered β-catenin to bind with E3 ligase (βTrCP) to promote β-catenin degradation. Finally by employing systematic ChIP studies, we showed ERα can interact directly with the β-catenin promoter region following E2 treatment. All our results reveal that estrogen and ERα blocked metastatic function of HA22T cells by modulating GSK3β and βTrCP expression and further enhanced β-catenin degradation and suppressed its downstream target genes. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 519-529, 2017.

Pharmacophore-based screening and drug repurposing exemplified on glycogen synthase kinase-3 inhibitors

The current study was conducted to elaborate a novel pharmacophore model to accurately map selective glycogen synthase kinase-3 (GSK-3) inhibitors, and perform virtual screening and drug repurposing. Pharmacophore modeling was developed using PHASE on a data set of 203 maleimides. Two benchmarking validation data sets with focus on selectivity were assembled using ChEMBL and PubChem GSK-3 confirmatory assays. A drug repurposing experiment linking pharmacophore matching with drug information originating from multiple data sources was performed. A five-point pharmacophore model was built consisting of a hydrogen bond acceptor (A), hydrogen bond donor (D), hydrophobic (H), and two rings (RR). An atom-based 3D quantitative structure-activity relationship (QSAR) model showed good correlative and satisfactory predictive abilities (training set [Formula: see text]; test set: [Formula: see text]; whole data set: stability [Formula: see text]). Virtual screening experiments revealed that selective GSK-3 inhibitors are ranked preferentially by Hypo-1, but fail to retrieve nonselective compounds. The pharmacophore and 3D QSAR models can provide assistance to design novel, potential GSK-3 inhibitors with high potency and selectivity pattern, with potential application for the treatment of GSK-3-driven diseases. A class of purine nucleoside antileukemic drugs was identified as potential inhibitor of GSK-3, suggesting the reassessment of the target range of these drugs.

Radiotherapy plus EGFR inhibitors: synergistic modalities

Locally advanced (stage III or IV) squamous cell carcinoma of the head and neck (SCCHN) often requires multimodal treatment, consisting of a combination of surgery, radiation, and/or systemic therapy, namely chemotherapy or targeted agents. The expression of the epidermal growth factor receptor (EGFR) has been detected in more than 90% of all cases of SCCHN and has been correlated with decreased survival rates, resistance to radiotherapy, loco-regional treatment failure, and increased rates of distant metastases. This paper discusses several strategies aimed at targeting EGFR in combination with radiation. Until now, cetuximab, an anti-EGFR monoclonal antibody, is the only targeted agent that has been shown to improve overall survival in combination with radiation therapy. However, considering that there are multiple mechanisms of primary and acquired resistance to EGFR inhibitors, we focused on dissecting molecular pathways of EGFR inhibition to find alternative or complementary strategies for increasing tumour responsiveness. We suggest that the combination of treatments targeting the EGFR pathway and drugs aimed at increasing immune responses represent a promising approach that deserves to be further explored.