The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma

KIF4A promotes epithelial-mesenchymal transition by activating the TGF-β/SMAD signaling pathway in glioma cells

Gliomas are the most prevalent type of primary brain tumor, with poor prognosis reported in patients with high-grade glioma. Kinesin family member 4 A (KIF4A) stimulates the proliferation, migration, and invasion of tumor cells. However, its function in gliomas has not been clearly established. Therefore, this study aimed to investigate the effects of KIF4A on the epithelial-mesenchymal transition and invasion of glioma cells. We searched The Cancer Genome Atlas and Chinese Glioma Genome Atlas databases to identify KIF4A-related signaling pathways and downstream genes. We further validated them using western blotting, transwell migration and invasion, wound-healing scratch, and dual-luciferase reporter assays in U251 and U87 human glioblastoma cells. Our analysis of the Cancer Genome Atlas and Chinese Glioma Genome Atlas data showed elevated KIF4A expression in patients with gliomas and was associated with clinical grade. Here, KIF4A overexpression promoted the migration, invasion, and proliferation of glioma cells, whereas KIF4A knockdown showed contrasting results. Gene Ontology (GO) and Gene Set Enrichment Analysis (GSEA) analyses demonstrated that KIF4A positively controls TGF-β/SMAD signaling in glioma cells. Additionally, genetic correlation analysis revealed that KIF4A transcriptionally controls benzimidazoles-1 expression in glioma cells. KIF4A promotes the epithelial-mesenchymal transition by regulating the TGF-β/SMAD signaling pathway via benzimidazoles-1 in glioma cells.

Lipocalin-2 inhibits pancreatic cancer stemness via the AKT/c-Jun pathway

Cancer stem cells (CSCs) are involved in cancer recurrence and metastasis owing to their self-renewal properties and drug-resistance capacity. Lipocalin-2 (Lcn2) of the lipocalin superfamily is highly expressed in pancreatic cancer. Nevertheless, reports on the involvement of Lcn2 in the regulation of pancreatic CSC properties are scant. This study is purposed to investigate whether Lcn2 plays a crucial role in CSC renewal and stemness maintenance in pancreatic carcinoma. Immunohistochemistry results of tumor tissue chips together with Gene Expression Omnibus sequencing files confirmed that Lcn2 is highly expressed in pancreatic carcinoma compared with that in normal tissues. The exogenous expression of Lcn2 attenuated CSC-associated SOX2, CD44, and EpCAM expression and suppressed sarcosphere formation and tumorigenesis in the pancreatic carcinoma cell line PANC-1, which showed low expression of Lcn2. However, Lcn2 knockout in BxPC-3 cell line, which presented high Lcn2 expression, promoted CSC stemness, further enhancing sarcosphere formation and tumorigenesis. Moreover, Lcn2 was found to regulate stemness in pancreatic cancer depending on the activation of AKT and c-Jun. Lcn2 suppresses stemness properties in pancreatic carcinoma by activating the AKT-c-Jun pathway, and thus, it may be a novel candidate to suppress the stemness of pancreatic cancer. This study provides a new insight into disease progression.

MicroRNA Interrelated Epithelial Mesenchymal Transition (EMT) in Glioblastoma

MicroRNAs (miRNA) are small non-coding RNAs that are 20–23 nucleotides in length, functioning as regulators of oncogenes or tumor suppressor genes. They are molecular modulators that regulate gene expression by suppressing gene translation through gene silencing/degradation, or by promoting translation of messenger RNA (mRNA) into proteins. Circulating miRNAs have attracted attention as possible prognostic markers of cancer, which could aid in the early detection of the disease. Epithelial to mesenchymal transition (EMT) has been implicated in tumorigenic processes, primarily by promoting tumor invasiveness and metastatic activity; this is a process that could be manipulated to halt or prevent brain metastasis. Studies show that miRNAs influence the function of EMT in glioblastomas. Thus, miRNA-related EMT can be exploited as a potential therapeutic target in glioblastomas. This review points out the interrelation between miRNA and EMT signatures, and how they can be used as reliable molecular signatures for diagnostic purposes or targeted therapy in glioblastomas.

PDK1 Inhibitor BX795 Improves Cisplatin and Radio-Efficacy in Oral Squamous Cell Carcinoma by Downregulating the PDK1/CD47/Akt-Mediated Glycolysis Signaling Pathway

Background: Oral squamous cell carcinoma (OSCC) has a high prevalence and predicted global mortality rate of 67.1%, necessitating better therapeutic strategies. Moreover, the recurrence and resistance of OSCC after chemo/radioresistance remains a major bottleneck for its effective treatment. Molecular targeting is one of the new therapeutic approaches to target cancer. Among a plethora of targetable signaling molecules, PDK1 is currently rising as a potential target for cancer therapy. Its aberrant expression in many malignancies is observed associated with glycolytic re-programming and chemo/radioresistance. Methods: Furthermore, to better understand the role of PDK1 in OSCC, we analyzed tissue samples from 62 patients with OSCC for PDK1 expression. Combining in silico and in vitro analysis approaches, we determined the important association between PDK1/CD47/LDHA expression in OSCC. Next, we analyzed the effect of PDK1 expression and its connection with OSCC orosphere generation and maintenance, as well as the effect of the combination of the PDK1 inhibitor BX795, cisplatin and radiotherapy in targeting it. Results: Immunohistochemical analysis revealed that higher PDK1 expression is associated with a poor prognosis in OSCC. The immunoprecipitation assay indicated PDK1/CD47 binding. PDK1 ligation significantly impaired OSCC orosphere formation and downregulated Sox2, Oct4, and CD133 expression. The combination of BX795 and cisplatin markedly reduced in OSCC cell’s epithelial-mesenchymal transition, implying its synergistic effect. p-PDK1, CD47, Akt, PFKP, PDK3 and LDHA protein expression were significantly reduced, with the strongest inhibition in the combination group. Chemo/radiotherapy together with abrogation of PDK1 inhibits the oncogenic (Akt/CD47) and glycolytic (LDHA/PFKP/PDK3) signaling and, enhanced or sensitizes OSCC to the anticancer drug effect through inducing apoptosis and DNA damage together with metabolic reprogramming. Conclusions: Therefore, the results from our current study may serve as a basis for developing new therapeutic strategies against chemo/radioresistant OSCC.

Curcumol inhibits the malignant progression of prostate cancer and regulates the PDK1/AKT/mTOR pathway by targeting miR‑9

Curcumol has been reported to exert anti-tumor activity, but its intrinsic molecular mechanism in prostate cancer remains to be elucidated. The present study aimed to analyze the effect of curcumol on prostate cancer and identify its possible internal regulatory pathway using in vitro cell culture and in vivo tumor model experiments. The cytotoxicity of curcumol was detected using a Cell Counting Kit-8 assay and it was found that curcumol had no obvious toxicity or side effects on RWPE-1 cells. Wound healing, Transwell and flow cytometry assays demonstrated that curcumol could affect the activity of PC3 cells. The luciferase reporter assay also indicated that microRNA (miR)-9 could directly target pyruvate dehydrogenase kinase 1 (PDK1). After PC3 cells were transfected with miR-9 inhibitor or treated with curcumol, the expression levels of the PDK1/AKT/mTOR signaling pathway-related proteins [PDK1, phosphorylated (p)-AKT and p-mTOR] were increased or decreased, respectively. Next, the prostate cancer cell xenograft model was established. Tumor size and the expression levels of PDK1/AKT/mTOR signaling pathway-related factors were altered following treatment with curcumol. The in vitro and in vivo experiments collectively demonstrated that curcumol could inhibit the PDK1/AKT/mTOR signaling pathway by upregulating the expression level of miR-9. The present study found that curcumol regulates the PDK1/AKT/mTOR signaling pathway via miR-9 and affects the development of prostate cancer. These findings could provide a possible scientific insight for research into treatments for prostate cancer.

POU2F2 regulates glycolytic reprogramming and glioblastoma progression via PDPK1-dependent activation of PI3K/AKT/mTOR pathway

The POU Class Homeobox 2 (POU2F2) is a member of POU transcription factors family, which involves in cell immune response by regulating B cell proliferation and differentiation genes. Recent studies have shown that POU2F2 acts as tumor-promoting roles in some cancers, but the underlying mechanism remains little known. Here, we identified that the highly expressed POU2F2 significantly correlated with poor prognosis of glioblastoma (GBM) patients. POU2F2 promoted cell proliferation and regulated glycolytic reprogramming. Mechanistically, the AKT/mTOR signaling pathway played important roles in the regulation of POU2F2-mediated aerobic glycolysis and cell growth. Furthermore, we demonstrated that POU2F2 activated the transcription of PDPK1 by directly binding to its promoter. Reconstituted the expression of PDPK1 in POU2F2-knockdown GBM cells reactivated AKT/mTOR pathway and recovered cell glycolysis and proliferation, whereas this effect was abolished by the PDPK1/AKT interaction inhibitor. In addition, we showed that POU2F2-PDPK1 axis promoted tumorigenesis by regulating glycolysis in vivo. In conclusion, our findings indicate that POU2F2 leads a metabolic shift towards aerobic glycolysis and promotes GBM progression in PDPK1-dependent activation of PI3K/AKT/mTOR pathway.

miR-4286 is Involved in Connections Between IGF-1 and TGF-β Signaling for the Mesenchymal Transition and Invasion by Glioblastomas

The insulin-like growth factor (IGF)-1 and transforming growth factor (TGF)-β signal pathways are both recognized as important in regulating cancer prognosis, such as the epithelial-to-mesenchymal transition (EMT) and cell invasion. However, cross-talk between these two signal pathways in glioblastoma multiforme (GBM) is still unclear. In the present study, by analyzing data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GSE) 4412, GBM patients with higher IGF-1 levels exhibited poorer survival. Genes positively correlated with IGF-1 were enriched in EMT and TGF-β signal pathways. IGF-1 treatment enhanced mesenchymal marker expressions and GBM cell invasion. A significant positive correlation was observed for IGF-1 with TGF-β1 (TGFB1) or TGF-β receptor 2 (TGFBR2), both of which participate in TGF-β signaling and are risk genes in the GBM process. IGF-1 stimulation promoted both TGFB1 and TGFBR2 expressions. LY2157299, a TGF-β signaling inhibitor, attenuated IGF-1-enhanced GBM cell invasion and mesenchymal transition. By analyzing IGF-1-regulated microRNA (miR) profiles, miR-4286 was found to be significantly downregulated in IGF-1-treated cells and could be targeted to both TGFB1 and TGFBR2. Overexpression of miR-4286 significantly attenuated expressions of the IGF-1-mediated mesenchymal markers, TGFB1 and TGFBR2. Using kinase inhibitors, only U0126 treatment showed an inhibitory effect on IGF-1-reduced miR-4286 and IGF-1-induced TGFB1/TGFBR2 expressions, suggesting that MEK/ERK signaling is involved in the IGF-1/miR-4286/TGF-β signaling axis. Finally, our results suggested that miR-4286 might act as a tumor suppressive microRNA in inhibiting IGF-1-enhanced GBM cell invasion. In conclusion, IGF-1 is connected to TGF-β signaling in regulating the mesenchymal transition and cell invasion of GBM through inhibition of miR-4286. Our findings provide new directions and mechanisms for exploring GBM progression.

Pentraxin 3 Promotes Glioblastoma Progression by Negative Regulating Cells Autophagy

Glioblastoma is the most malignancy tumor generated from the central nervous system along with median survival time less than 14.6 months. Pentraxin 3 has been proved its association with patients’ poor survival outcome in various tumor. Recently, several studies revealed its association with glioblastoma progression but the mechanism is remained unknown. Autophagy is a programmed cells death and acts critical role in tumor progression. In this study, pentraxin 3 is recognized as prognostic prediction biomarker of glioblastoma and can promote glioblastoma progression through negative modulating tumor cells autophagy. Transcription factor JUN is assumed to participate in cells autophagy modulation by regulating pentraxin 3 expression. This work reveals novel mechanism of pentraxin 3 mediated glioblastoma progression. Furthermore, JUN is identified as potential transcription factor involves in pentraxin 3 mediated tumor cells autophagy.

Phospho-inositide-dependent kinase 1 regulates signal dependent translation in megakaryocytes and platelets

BACKGROUND

Regulated protein synthesis is essential for megakaryocyte (MK) and platelet functions, including platelet production and activation. PDK1 (phosphoinositide-dependent kinase 1) regulates platelet functional responses and has been associated with circulating platelet counts. Whether PDK1 also directly regulates protein synthetic responses in MKs and platelets, and platelet production by MKs, remains unknown.

OBJECTIVE

To determine if PDK1 regulates protein synthesis in MKs and platelets.

METHODS

Pharmacologic PDK1 inhibitors (BX-795) and mice where PDK1 was selectively ablated in MKs and platelets (PDK1-/- ) were used. PDK1 signaling in MKs and platelets (human and murine) were assessed by immunoblots. Activation-dependent translation initiation and protein synthesis in MKs and platelets was assessed by probing for dissociation of eIF4E from 4EBP1, and using m7-GTP pulldowns and S35 methionine incorporation assays. Proplatelet formation by MKs, synthesis of Bcl-3 and MARCKs protein, and clot retraction were employed for functional assays.

RESULTS

Inhibiting or ablating PDK1 in MKs and platelets abolished the phosphorylation of 4EBP1 and eIF4E by preventing activation of the PI3K and MAPK pathways. Inhibiting PDK1 also prevented dissociation of eIF4E from 4EBP1, decreased binding of eIF4E to m7GTP (required for translation initiation), and significantly reduced de novo protein synthesis. Inhibiting PDK1 reduced proplatelet formation by human MKs and blocked MARCKs protein synthesis. In both human and murine platelets, PDK1 controlled Bcl-3 synthesis. Inhibition of PDK1 led to complete failure of clot retraction in vitro.

CONCLUSIONS

PDK1 is a previously unidentified translational regulator in MKs and platelets, controlling protein synthetic responses, proplatelet formation, and clot retraction.

Effects of cisatracurium on epithelial-to-mesenchymal transition in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive types of cancer worldwide, with a poor prognosis. The aim of the present study was to investigate the effect of cisatracurium (Cis) on epithelial-to-mesenchymal transition (EMT) in ESCC and its potential mechanism of action. In the present study, Cis was used to treat ECA-109 cells, with cell proliferation measured by a Cell Counting Kit-8 assay and the expression of TGF-β and phospho-Smad2/3 detected by western blotting. TGF-β was then applied to induce EMT. Flow cytometry, wound healing and Transwell assays were used to evaluate cell proliferation, apoptosis, invasion and migration. In addition, cell cycle-related proteins, including cyclin D1, p53 and p21, and EMT-associated proteins, including E-cadherin (E-cad), N-cadherin (N-cad), Vimentin and Slug, were examined by western blot analysis. The results revealed that Cis inhibited the proliferation and promoted apoptosis of ESCC cells. Following treatment with Cis, the expression of TGF-β and phosphorylation of Smad2/3 were downregulated. Cis also suppressed cancer cell invasion and migration induced by TGF-β. In addition, the expression levels of cyclin D1 were decreased, accompanied by increased p53 and p21 expression. In addition, the expression level of E-cad was increased, whereas N-cad, Vimentin and Slug were significantly reduced. Taken together, the results of the present study revealed that exposure of ESCC cells to Cis inhibited EMT and reduced cell invasion and metastasis through the TGF-β/Smad signaling pathway.

Overexpression of E74-Like Factor 5 (ELF5) Inhibits Migration and Invasion of Ovarian Cancer Cells

Background

E74-like factor 5 (ELF5) plays a key role in the processes of cell differentiation, apoptosis, and occurrence of tumors. However, the effect of ELF5 on metastasis and invasion in human ovarian cancer remains poorly understood.

Material/Methods

Quantitative real-time polymerase chain reaction (qPCR) was performed to measure the expression of ELF5. The viability of cells was detected by cell counting kit (CCK-8). Cell apoptosis was tested by flow cytometry. Matrigel plug angiogenesis assay was employed to determine angiogenesis rate. The protein expression levels of vascular endothelial growth factor (VEGF), cleaved caspase-3, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), E-cadherin, N-cadherin, Snail, phosphoinositide 3 kinase (PI3K), phosphorylated (p)-PI3K, tyrosine kinase B (AKT), and phosphorylated (p)-AKT were determined by Western blot. Wound-healing assay and Transwell were used to determine invasion and migration.

Results

We found that expression of ELF5 was obviously decreased in ovarian cancer cell lines. The cells viability, invasion and metastasis were inhibited by overexpression ELF5. ELF5 suppressed angiogenesis rate and the expression of VEGF. Changes of the expressions of Bcl-2, cleaved caspase-3 and Bax showed that anti-apoptosis ability was improved by ELF5. ELF5 also repressed N-cadherin and Snail and increased E-cadherin. The expressions of p-PI3K and p-AKT were decreased by ELF5. Further study showed that IGF-I reversed the inhibitory effect of ELF5 on growth and metastasis of SKOV3 cells.

Conclusions

Overexpression of ELF5 promoted the apoptosis and reduced the migration and invasion of ovarian cancer cells; therefore, it could provide a new approach to gene treatment of ovarian carcinoma.

Knockdown of BRCC3 exerts an anti‑tumor effect on cervical cancer in vitro

Cervical cancer is a serious malignancy that affects the health of females. In the present study, the association between breast cancer type 1 susceptibility protein/breast cancer type 2 susceptibility protein-containing complex subunit 3 (BRCC3) and cervical cancer was investigated. Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to determine BRCC3 mRNA and protein expression levels in cervical cancer tissues and cells, in addition to the expression levels of proteins associated with the epithelial-mesenchymal transition (EMT) process in HeLa and SiHa cells. Cell Counting Kit-8, Transwell and wound healing assays were performed to determine the cell viability, invasion and migration abilities of cervical cancer cells, respectively. The results of the present study revealed that BRCC3 expression was significantly increased in cervical cancer tissues, which was also revealed to be associated with the clinical stages and pathological grades of cervical cancer exhibited by patients, in addition to the survival time. Furthermore, BRCC3 expression levels were enhanced in HeLa, SiHa and C-33A cervical cancer cells. BRCC3 interference in HeLa and SiHa cells was revealed to suppress cell viability, invasion and migration abilities via upregulation of E-cadherin expression levels and downregulation of Vimentin, matrix metalloproteinase (MMP)-2, MMP-9, snail family transcriptional repressor (Snai)1 and Snai2 expression levels. In conclusion, the expression levels of BRCC3 were revealed to be increased in cervical cancer tissues, which were positively associated with clinical features of cervical cancer. Furthermore, BRCC3 interference inhibited the cell viability, invasion and migration abilities of HeLa and SiHa cells via regulation of EMT progression and expression levels of Snai family members. In addition, the results of the present study suggested that BRCC3 represents an oncogene associated with cervical cancer, and may also represent a novel therapeutic biomarker for the diagnosis, treatment and prognosis of patients with cervical cancer.