Acylglycerol kinase promotes the proliferation and cell cycle progression of oral squamous cell carcinoma

Circ_0008068 facilitates the oral squamous cell carcinoma development by microRNA-153-3p/acylgycerol kinase (AGK) axis

Oral squamous cell carcinoma (OSCC) is a common cancer with high recurrence, metastasis rates and poor prognosis. Circular RNAs (circRNAs) take part in regulating OSCC. Herein, we examined the role of circ_0008068 in OSCC. The circ_0008068, Katanin p60 ATPase-containing subunit A-like 1 (KATNAL1) mRNA, microRNA-153-3p (miR-153-3p) and acylgycerol kinase (AGK) contents were indicated by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Moreover, in vitro and in vivo assays were conducted to scrutinize the effects of circ_0008068 on OSCC. Additionally, the contact between miR-153-3p and circ_0008068 or AGK was assessed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Thereafter, we found that the appearance of circ_0008068 and AGK was increased, and miR-153-3p content was diminished in OSCC. Circ_0008068 lack subdued cell proliferation, migration, invasion, tube formation and glycolysis metabolism, but stimulated cell apoptosis in OSCC. In addition, circ_0008068 bound to miR-153-3p to modulate the expression of its target AGK. Besides, miR-153-3p was validated to act as a tumor suppressor in OSCC tumorigenesis by suppressing AGK. Additionally, circ_0008068 knockdown also attenuated tumor growth in nude mice. In all, circ_0008068 expedited the growth of OSCC by miR-153-3p/AGK axis.

Abbreviations: OSCC: Oral squamous cell carcinoma; AGK: Acylgycerol kinase; CircRNA: Circular RNA; KATNAL1: Katanin p60 ATPase-containing subunit A-like 1; qRT-PCR: Quantitative real-time polymerase chain reaction; miRNAs/miRs: MicroRNAs; RIP: RNA immunoprecipitation; 3′UTR3’: -untranslated region; HK2: Hexokinase 2; LDHA Lactate dehydrogenase A; IHC: Immunohistochemistry; CCK8: Cell counting kit-8; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase

Acylglycerol kinase promotes paclitaxel resistance in nasopharyngeal carcinoma cells by regulating FOXM1 via the JAK2/STAT3 pathway

OBJECTIVE

Drug resistance is an important factor that impedes the treatment of nasopharyngeal cancer (NPC). Acylglycerol kinase (AGK) has been found to be overexpressed in NPC and correlates with poor prognosis. Our objective was to demonstrate the effect of AGK on paclitaxel resistance in NPC and determine the underlying mechanisms.

METHODS

MTT assay was employed to determine the IC50 of paclitaxel in NPC cells after different treatments. Flow cytometry assays were employed to evaluate cell apoptosis. RT-qPCR and Western blot assays were used to detect alterations in mRNA and protein expression, respectively. Luciferase assays and chromatin immunoprecipitation (ChIP) assays were used to determine the relationship between and the regulatory effect of STAT3 on the promoter of FOXM1.

RESULTS

AGK was elevated in paclitaxel-resistant NPC cells, and knockdown of AGK suppressed the resistance of CNE1-TR and CNE2-TR cells to paclitaxel. Moreover, upregulation of FOXM1 rescued the effects of AGK knockdown. Furthermore, the JAK2/STAT3 signalling pathway was overactivated in CNE1-TR and CNE2-TR cells, and knockdown of AGK suppressed JAK2/STAT3 signalling. STAT3 was verified to bind to and activate the promoter region of FOXM1. An in vivo tumour xenograft assay also verified that AGK knockdown inhibited tumour growth and mitigated paclitaxel resistance by regulating the JAK2/STAT3/FOXM1 axis.

CONCLUSION

AGK levels were increased in paclitaxel-resistant NPC cells. AGK activates JAK2/STAT3 signalling, thus promoting FOXM1 transcription and eventually enhancing the drug resistance of NPC cells.

Mitochondrial protein import dysfunction: mitochondrial disease, neurodegenerative disease and cancer

The majority of proteins localised to mitochondria are encoded by the nuclear genome, with approximately 1500 proteins imported into mammalian mitochondria. Dysfunction in this fundamental cellular process is linked to a variety of pathologies including neuropathies, cardiovascular disorders, myopathies, neurodegenerative diseases and cancer, demonstrating the importance of mitochondrial protein import machinery for cellular function. Correct import of proteins into mitochondria requires the co-ordinated activity of multimeric protein translocation and sorting machineries located in both the outer and inner mitochondrial membranes, directing the imported proteins to the destined mitochondrial compartment. This dynamic process maintains cellular homeostasis, and its dysregulation significantly affects cellular signalling pathways and metabolism. This review summarises current knowledge of the mammalian mitochondrial import machinery and the pathological consequences of mutation of its components. In addition, we will discuss the role of mitochondrial import in cancer, and our current understanding of the role of mitochondrial import in neurodegenerative diseases including Alzheimer's disease, Huntington's disease and Parkinson's disease.

Up-regulated acylglycerol kinase (AGK) expression associates with gastric cancer progression through the formation of a novel YAP1-AGK-positive loop

Acylglycerol kinase (AGK) uses adenosine triphosphate (ATP) and acylglycerol to generate adenosine diphosphate (ADP) and acyl‐sn‐glycerol 3‐phosphate in cells. Recent evidence has demonstrated that dysregulated AGK expression is associated with the development of various human cancers. This study investigated the effects of AGK on gastric cancer cell proliferation and carcinogenesis and explored the underlying molecular events. AGK expression was up‐regulated in gastric cancer and was associated with poor prognosis in gastric cancer patients. AGK overexpression increased gastric cancer proliferation, invasion capacity and the expression of the epithelial‐mesenchymal transition markers in vitro. Conversely, the knockdown of AGK expression reduced gastric cancer cell proliferation in vitro and in nude mouse tumour cell xenografts. Importantly, AGK expression was associated with the YAP1 expression in gastric cancer cells and tissues. YAP1 expression also transcriptionally induced AGK expression through the binding of TEAD to the AGK gene promoter. However, AGK expression inhibited the activation of the Hippo pathway proteins and induced YAP1 nuclear localization to enhance the transcription activity of YAP1/TEADs. In conclusion, the study demonstrates that AGK is not only a novel target of the Hippo‐YAP1 pathway, but that it also positively regulates YAP1 expression, thus forming a YAP1‐AGK–positive feedback loop.

Acylglycerol kinase promotes tumour growth and metastasis via activating the PI3K/AKT/GSK3β signalling pathway in renal cell carcinoma

BACKGROUND

Clinically, the median survival in patients with metastatic renal cell carcinoma (RCC) was only 6-12 months and a 5-year survival rate of less than 20%. Therefore, an in-depth study of the molecular mechanisms involved in RCC is of great significance for improving the survival of patients with advanced RCC. Acylglycerol kinase (AGK) is a newly discovered lipid kinase that has been reported to be a potent oncogene that may be involved in the regulation of malignant progression in a variety of tumours. However, the expression and biological characteristics of the AGK gene in RCC remain unclear.

METHODS

AGK expression was quantified by quantitative real-time PCR, Western blotting and immunohistochemistry in RCC cell lines and paired patient tissues. Kaplan-Meier method and Cox proportional hazards models were used to evaluate the prognostic value of AGK in human RCC tissue samples. Chi-squared test was performed to analyse the correlation between AGK expression and the clinicopathological features. Stable overexpression and knockdown of AGK in RCC cells was constructed with lentivirus. The oncogenic effects of AGK in human RCC progression were investigated using assays of colony formation, anchorage-independent growth, EdU assay, cell cycle analysis, wound-healing, trans-well analysis and xenograft tumour model. GSEA and KEGG analysis were conducted to detect the potential pathway of AGK involved in RCC. These results were further confirmed using the luciferase reporter assays, immunofluorescence and in vivo experiments.

RESULTS

AGK expression is significantly elevated in RCC and closely related to the malignant development and poor prognosis in RCC patients. By in vitro and in vivo experiments, AGK was shown to enhance the proliferation of RCC cells by promoting the transition from the G1 phase to the S phase in the cell cycle and to enhance the migration and invasion by promoting epithelial-mesenchymal transition. By activating the PI3K/AKT/GSK3β signalling pathway in RCC, AGK can increase nuclear accumulation of β-catenin, which further upregulated TCF/LEF transcription factor activity.

CONCLUSIONS

AGK promotes the progression of RCC via activating the PI3K/AKT/GSK3β signalling pathway and might be a potential target for the further research of RCC.

Ophiopogonin D inhibits cell proliferation and induces apoptosis of human laryngocarcinoma through downregulation of cyclin B1 and MMP-9 and upregulation of p38-MAPK signaling

The pharmacological actions of Ophiopogonin D include resistance to cardiovascular and cerebrovascular diseases, anti-aging effects, improvement in learning deficit and dysmnesia, anti-tumor, anti-radiation and anti-inflammatory effects, immunoregulation, and the relief of cough and hepatopulmonary pathological lesions. However, the efficacy of Ophiopogonin D on human laryngocarcinoma remains to be elucidated. The present study therefore investigated whether the anti-cancer effect of Ophiopogonin D inhibits cell proliferation and induces apoptosis of human laryngocarcinoma. In the present study, it was found that Ophiopogonin D inhibited cell proliferation, promoted cytotoxicity, induced apoptosis and increased caspase-3/9 activity in human laryngocarcinoma cells. Ophiopogonin D significantly suppressed cyclin B1 and matrix metalloproteinase-9 (MMP-9) protein expression, and upregulated p-p38 MAPK protein expression in human laryngocarcinoma cells. Together, these results suggest Ophiopogonin D inhibits cell proliferation and induced apoptosis in human laryngocarcinoma cells through downregulation of cyclin B1 and MMP-9 and upregulation of the p38 MAPK signaling pathway. Therefore, Ophiopogonin D may be a potential therapy for the treatment of human laryngocarcinoma.

Effects of Quercetin on Proliferation and H₂O₂-Induced Apoptosis of Intestinal Porcine Enterocyte Cells

Weanling stress and toxicosis, which are harmful to the health of pigs' intestines, are associated with oxidative stress. Quercetin (Que) is a polyphenolic compound that shows good anti-cancer, anti-inflammation and anti-oxidation effects. This study aimed to elaborate whether or not Que promotes IPEC-J2 (intestinal porcine enterocyte cells) proliferation and protects IPEC-J2 from oxidative damage. Thus, we examined the effects of Que on proliferation and H₂O₂-induced apoptosis in IPEC-J2. The results showed that Que increased IPEC-J2 viabililty, propelled cells from G1 phase into S phase and down-regulated gene levels of P27 and P21, respectively. Besides, H₂O₂-induced cell damage was alleviated by Que after different exposure times, and Que depressed apoptosis rate, reactive oxygen species (ROS) level and percentage of G1 phase cells and elevated the percentage of cells in G2 phase and S phase and mitochondrial membrane potential (Δψm) after IPEC-J2 exposure to H₂O₂. Meanwhile, Que reduced the value of Bax/Bcl-2 in H₂O₂ exposed cells. In low-degree oxidative damage cells, lipid peroxidation product malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were increased. In turn, Que could reverse the change of MDA content and SOD activity in low-degree damage cells. Nevertheless, catalase (CAT) activity was not changed in IPEC-J2 incubated with Que under low-degree damage conditions. Interestingly, relative expressive levels of the proteins claudin-1 and occludin were not altered under low-degree damage conditions, but Que could improve claudin-1 and occludin levels, slightly. This research indicates that Que can be greatly beneficial for intestinal porcine enterocyte cell proliferation and it protects intestinal porcine enterocyte cells from oxidation-induced apoptosis, and could be used as a potential feed additive for porcine intestinal health against pathogenic factor-induced oxidative damages and apoptosis.

Down-regulated PLAC8 promotes hepatocellular carcinoma cell proliferation by enhancing PI3K/Akt/GSK3β/Wnt/β-catenin signaling

Hepatocellular carcinoma (HCC) is a common, prevalent malignancy. Its poor prognosis is mainly related to high rate of diagnosis in non-curable stages, in which patients are suitable for palliative treatment. Placenta-specific 8 (PLAC8), also known as Onzin, is a small, highly conserved, cysteine-rich protein. In current study, we found that PLAC8 is prominently decreased in HCC tissues compared with adjacent tissues and patients with low level of PLAC8 suffered a poor prognosis. In addition, cellular function assays demonstrate that down-regulated PLAC8 promotes cell viability, proliferation and tumor formation both in vitro and in vivo. Furthermore, we validate that down-regulated PLAC8 enhances the activity of PI3K/Akt/GSK3β and Wnt/β-catenin signaling to promote cell proliferation. Moreover, we proved that highly expressed miR-185-5p targets PLAC8 in HCC tissues. In conclusion, our findings enlarged our knowledge about the roles of PLAC8 in HCC progression and miR-185-5p/PLAC8/β-catenin axis might be a novel pathway for HCC treatment.

Acylglycerol kinase functions as an oncogene and an unfavorable prognostic marker of human gliomas

Acylglycerol kinase (AGK) regulates various cellular processes involved into tumorigenesis and tumor progression. To investigate involvement of AGK in human gliomas, here, quantitative real-time polymerase chain reaction, Western blot, and immunohistochemistry analyses were performed to respectively detect the expression of AGK mRNA and protein in glioma and nonneoplastic brain tissue specimens. Then, the associations of AGK expression with various clinicopathological characteristics and patients' prognosis were statistically evaluated. Moreover, the effects of siRNA-mediated AGK knockdown on glioma cell proliferation, migration, and invasion were respectively assessed via Cell Counting Kit-8 and Transwell assays in vitro. As a result, AGK expression, at both mRNA and protein levels, were markedly up-regulated in glioma tissues compared with nonneoplastic brain tissues (both P < .001). In addition, high AGK expression was significantly associated with the grade of malignancy and poor prognosis in glioma patients (all P < .05). Importantly, Cox regression model of multivariate analysis identified AGK expression as an independent prognostic factor for glioma patients (P = .03). Furthermore, silencing the expression of AGK dramatically suppressed cell proliferation, migration, and invasion of glioma cells in vitro (all P < .05). In conclusion, AGK up-regulation may be involved into glioma development and progression, highlighting its prognostic value for the treatment of patients with this malignancy. Further loss-of-function experiments suggest that AGK might play an important role in the viability and motility of glioma cells, implying its potentials as an attractive therapeutic target for this tumor.

Overexpression of acylglycerol kinase is associated with poorer prognosis and lymph node metastasis in nasopharyngeal carcinoma

Acylglycerol kinase (AGK) has been reported to promote a malignant phenotype and enhance the development of cancer stem cells. However, the clinical value of AGK in cancer remains unclear. This study aimed to investigate the expression and clinicopathological significance of AGK in nasopharyngeal carcinoma (NPC). AGK was significantly upregulated in NPC cell lines and clinical specimens as indicated by real-time PCR and Western blotting. Among the AGK-positive cases, 52/114 (45.6 %) of the archived human NPC specimens expressed high levels of AGK. High expression of AGK was associated with significantly shorter overall and disease-free survival (P < 0.001 and P = 0.002; log-rank test) and was an independent prognostic factor for overall survival (P = 0.041; multivariate Cox analysis). High AGK expression was associated with lymph node metastasis (P < 0.001; chi-squared test) and was an independent predicted factor for lymph node metastasis in NPC (P = 0.032; multivariate logistic analysis). AGK is overexpressed and associated with disease progression and lymph node metastasis in NPC. AGK has potential as a novel prognostic factor for overall survival in NPC.