3-Phosphoinositide Dependent Protein Kinase-1 (PDK-1) Promotes Migration and Invasion in Gastric Cancer Cells Through Activating the NF-κB Pathway

Master kinase PDK1 in tumorigenesis

3-phosphoinositide-dependent protein kinase 1 (PDK1) is considered as master kinase regulating AGC kinase family members such as AKT, SGK, PLK, S6K and RSK. Although autophosphorylation regulates PDK1 activity, accumulating evidence suggests that PDK1 is manipulated by many other mechanisms, including S6K-mediated phosphorylation, and the E3 ligase SPOP-mediated ubiquitination and degradation. Dysregulation of these upstream regulators or downstream signals involves in cancer development, as PDK1 regulating cell growth, metastasis, invasion, apoptosis and survival time. Meanwhile, overexpression of PDK1 is also exposed in a plethora of cancers, whereas inhibition of PDK1 reduces cell size and inhibits tumor growth and progression. More importantly, PDK1 also modulates the tumor microenvironments and markedly influences tumor immunotherapies. In summary, we comprehensively summarize the downstream signals, upstream regulators, mouse models, inhibitors, tumor microenvironment and clinical treatments for PDK1, and highlight PDK1 as a potential cancer therapeutic target.

Glycyl-tRNA Synthetase (GARS) Expression Is Associated with Prostate Cancer Progression and Its Inhibition Decreases Migration, and Invasion In Vitro

Glycyl-tRNA synthetase (GARS) is a potential oncogene associated with poor overall survival in various cancers. However, its role in prostate cancer (PCa) has not been investigated. Protein expression of GARS was investigated in benign, incidental, advanced, and castrate-resistant PCa (CRPC) patient samples. We also investigated the role of GARS in vitro and validated GARS clinical outcomes and its underlying mechanism, utilizing The Cancer Genome Atlas Prostate Adenocarcinoma (TCGA PRAD) database. Our data revealed a significant association between GARS protein expression and Gleason groups. Knockdown of GARS in PC3 cell lines attenuated cell migration and invasion and resulted in early apoptosis signs and cellular arrest in S phase. Bioinformatically, higher GARS expression was observed in TCGA PRAD cohort, and there was significant association with higher Gleason groups, pathological stage, and lymph nodes metastasis. High GARS expression was also significantly correlated with high-risk genomic aberrations such as PTEN, TP53, FXA1, IDH1, SPOP mutations, and ERG, ETV1, and ETV4 gene fusions. Gene Set Enrichment Analysis (GSEA) of GARS through the TCGA PRAD database provided evidence for upregulation of biological processes such as cellular proliferation. Our findings support the oncogenic role of GARS involved in cellular proliferation and poor clinical outcome and provide further evidence for its use as a potential biomarker in PCa.

Research progress on the antitumor effects of astragaloside IV

One of the most important and effective components of Astragalus membranaceus is astragaloside IV (AS-IV), which can exert anti-tumor effects through various pathways. For instance, AS-IV exerts an anti-tumor effect by acting at the cellular level, regulating the phenotype switch of tumor-associated macrophages, or inhibiting the development of tumor cells. Furthermore, AS-IV inhibits tumor cell progression by enhancing its sensitivity to antitumor drugs or reversing the drug resistance of tumor cells. This article reviews the different mechanisms of AS-IV inhibition of epithelial-mesenchymal transition (EMT), migration, proliferation, and invasion of tumor cells, inducing apoptosis and improving the sensitivity of anti-tumor drugs. This review summarizes recent progress in the current research into AS-IV anti-tumor effect and provides insight on the next anti-tumor research of AS-IV.

Essential role of aerobic glycolysis in epithelial-to-mesenchymal transition during carcinogenesis

Epithelial-to-mesenchymal transition (EMT) confers the most lethal characteristics to cancer cells i.e., metastasis and resistance to chemo-and-radio-therapy, and therefore exhibit an appealing target in the field of oncology. Research in the past decade has demonstrated the crucial role of aerobic glycolysis in EMT, which is generally credited as the glucose metabolism for the creation of biomass such as fatty acids, amino acids, and nucleotides thereby providing building blocks for limitless proliferation. In the present review, apart from discussing EMT's evident role in the metastatic process and cancer stemness, we also talked about the vital role of glycolytic enzymes viz. GLUTs, HKs, PGI, PFK-1, aldolase, enolase, PK, LDHA, etc. in the induction of the EMT process in cancerous cells.

PDK4 Constitutes a Novel Prognostic Biomarker and Therapeutic Target in Gastric Cancer

Gastric cancer (GC) is one of the most prevalent and deadly malignancies worldwide. We aimed to assess the functional role and clinical significance of pyruvate dehydrogenase kinase (PDK) in GC and explored the underlying mechanisms. The bioinformatics method was used to investigate the expression of PDKs in GC, the effect on clinical outcomes, enriched pathways, interactive network, and the correlation between PDK4 and immune infiltration. Next, PDK expression in the GC cells and tissues were verified by qRT-PCR and western blotting. A Cell Counting Kit-8 (CCK8), colony-formation, Flow cytometry, Transwell and wound healing assays were carried out to evaluate the influence of PDK4 on cell proliferation, invasion and migration. Among PDKs, PDK4 expression was aberrant in GC and identified as an independent prognostic factor. GO analysis, GSEA, and PPI showed that PDK4 expression may regulate cell adhesion, metal ion transport, synaptic activity, and cancer cell metabolism in GC. Analyses of immune infiltration showed that PDK4 correlated with the abundant expression of various immunocytes. Finally, we verified that upregulation of PDK4 expression enhanced the ability of GC cells to proliferate, migrate, and invade. In conclusion, PDK4 was identified as a potential candidate diagnostic biomarker and therapeutic target for GC patients.

Quantifying the Patterns of Metabolic Plasticity and Heterogeneity along the Epithelial–Hybrid–Mesenchymal Spectrum in Cancer

Cancer metastasis is the leading cause of cancer-related mortality and the process of the epithelial-to-mesenchymal transition (EMT) is crucial for cancer metastasis. Both partial and complete EMT have been reported to influence the metabolic plasticity of cancer cells in terms of switching among the oxidative phosphorylation, fatty acid oxidation and glycolysis pathways. However, a comprehensive analysis of these major metabolic pathways and their associations with EMT across different cancers is lacking. Here, we analyse more than 180 cancer cell datasets and show the diverse associations of these metabolic pathways with the EMT status of cancer cells. Our bulk data analysis shows that EMT generally positively correlates with glycolysis but negatively with oxidative phosphorylation and fatty acid metabolism. These correlations are also consistent at the level of their molecular master regulators, namely AMPK and HIF1α. Yet, these associations are shown to not be universal. The analysis of single-cell data for EMT induction shows dynamic changes along the different axes of metabolic pathways, consistent with general trends seen in bulk samples. Further, assessing the association of EMT and metabolic activity with patient survival shows that a higher extent of EMT and glycolysis predicts a worse prognosis in many cancers. Together, our results reveal the underlying patterns of metabolic plasticity and heterogeneity as cancer cells traverse through the epithelial–hybrid–mesenchymal spectrum of states.

Towards decoding the coupled decision-making of metabolism and epithelial-to-mesenchymal transition in cancer

Cancer cells have the plasticity to adjust their metabolic phenotypes for survival and metastasis. A developmental programme known as epithelial-to-mesenchymal transition (EMT) plays a critical role during metastasis, promoting the loss of polarity and cell-cell adhesion and the acquisition of motile, stem-cell characteristics. Cells undergoing EMT or the reverse mesenchymal-to-epithelial transition (MET) are often associated with metabolic changes, as the change in phenotype often correlates with a different balance of proliferation versus energy-intensive migration. Extensive crosstalk occurs between metabolism and EMT, but how this crosstalk leads to coordinated physiological changes is still uncertain. The elusive connection between metabolism and EMT compromises the efficacy of metabolic therapies targeting metastasis. In this review, we aim to clarify the causation between metabolism and EMT on the basis of experimental studies, and propose integrated theoretical-experimental efforts to better understand the coupled decision-making of metabolism and EMT.

gga-miR-148a-5p-Targeting PDPK1 Inhibits Proliferation and Cell Cycle Progression of Avain Leukosis Virus Subgroup J (ALV-J)-Infected Cells

Avian leukosis virus subgroup J disease (ALV-J) is a contagious and immunosuppressive avian disease caused by ALV-J virus. Although miRNA participate in various biological processes of tumors, little is known about the potential role of miRNA in ALV-J. Our previous miRNA and RNA sequencing data showed that the expression of gga-miR-148a-5p was significantly different in ALV-J-infected chicken spleens compared with non-infected chickens. The aim of this study was to investigate the functional roles of gga-miR-148a-5p and identify downstream targets regulated by gga-miR-148a-5p in ALV-J-infected chickens. We found that the expression of gga-miR-148a-5p was significantly downregulated during ALV-J infection of chicken embryo fibroblasts (CEF). Dual luciferase reporter assays demonstrated that PDPK1 is a direct target gene of gga-miR-148a-5p. In vitro, overexpression of gga-miR-148a-5p significantly promoted ALV-J-infected CEF cell proliferation, included cell cycle, whereas inhibition of gga-miR-148a-5p had an opposite effect. Inhibition of PDPK1 promoted the proliferation of ALV-J-infected cells but had no effect on the activity of NF-κB. Together, these results suggested that gga-miR-148a-5p targets PDPK1 to inhibit the proliferation and cell cycle of ALV-J-infected CEF cells. Our study provides a new understanding for the tumor mechanism of ALV-J infection.

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.

High expression of the ANKRD49 protein is associated with progression and poor prognosis of gastric cancer

BACKGROUND

Gastric cancer is one of the most common malignant tumours. Identifying novel genes that govern the development of gastric cancer will help to elucidate its molecular mechanisms and find novel biomarkers.

METHODS

Expression of the ANKRD49 protein was assessed by immunohistochemical analysis of tissue microarrays containing 92 sets of human gastric cancer specimens with adjacent non-cancerous tissue. Associations between ANKRD49 levels and clinicopathological characteristics of the patient were investigated. The correlation between ANKRD49 expression and patient survival was analysed by the Kaplan-Meier method.

RESULTS

The results revealed that the expression level of the ANKRD49 protein in gastric cancer was significantly upregulated and correlated with the tumour size, tumour-node-metastasis (TNM) stage, histological grade, depth of invasion, vessel invasion, lymph node metastasis and distant metastasis. The mean survival time of patients with low expression levels of ANKRD49 was significantly longer than that of patients with high expression levels of ANKRD49. Multivariate Cox regression analysis demonstrated that the ANKRD49 protein expression level was an independent prognostic indicator for the survival rate of patients with gastric cancer.

CONCLUSION

The results of the present study highlighted an important role of the ANKRD49 protein in the progression of gastric cancer. The ANKRD49 protein could act as a potential biomarker for prognosis evaluation of gastric cancer and may be used as a molecular target for gastric cancer treatment.