Prognostic significance of AMPK in human malignancies: A meta-analysis

AMPK: An energy sensor for non-small cell lung cancer progression and treatment

Lung cancer (LC) is the leading cause of cancer-related morbidity and mortality in China, with non-small cell lung cancer (NSCLC) accounting for 85 % of the overall lung cancer cases. AMP-activated protein kinase (AMPK) is a key regulator of energy balance and homeostasis, and its dysregulation is a common feature in various malignancies, particularly in NSCLC with mutations in Liver kinase B1 (LKB1). Studies have shown that the AMPK signalling pathway has a dual role in NSCLC progression, both inhibiting and promoting the progression of malignant tumours. Therefore, drugs targeting the AMPK signalling pathway may hold significant promise for therapeutic application in NSCLC. This review aims to examine the manifestations and mechanisms by which AMPK and its associated signalling molecules influence NSCLC progression and treatment. Firstly, we discuss the critical importance of AMPK within the mutational context of NSCLC. Secondly, we summarise the drugs and related substances that modulate the AMPK signalling pathway in NSCLC and evaluate the evidence from preclinical studies on combination AMPK-targeted therapies to address the issue of drug resistance in NSCLC under current clinical treatments. In summary, this paper highlights the critical importance of developing AMPK-targeted drugs to enhance therapeutic efficacy in NSCLC, as well as the potential for applying these drugs in clinical therapy to overcome drug resistance.

Ad-apoptin inhibits glycolysis, migration and invasion in lung cancer cells targeting AMPK/mTOR signaling pathway

Ad-apoptin is a recombinant oncolytic adenovirus constructed by our laboratory that can express apoptin. It can selectively kill tumor cells without damaging normal cells. This study investigated the effects of Ad-apoptin on glycolysis, migration and invasion of non-small cell lung cancer. Cell viability and apoptosis were detected by CCK-8 and flow cytometry, respectively. Glycolysis was investigated by glucose consumption, lactic acid production and glycolytic key enzyme protein levels. Migration and invasion were evaluated via wound healing, transwell assays and epithelial-mesenchymal transition (EMT) protein levels. The interaction between apoptin and AMPK was detected by Co-IP. A nude mice tumor model was established to investigate the anti-cancer role of Ad-apoptin in vivo. The results showed that Ad-apoptin inhibits cell viability and induces apoptosis of A549 and NCI-H23 cells. Ad-apoptin can reduce the glucose uptake and lactic production in lung cancer cells, and reduce the expression of related glycolysis-limiting enzymes. At the same time, Ad-apoptin inhibited the migration and invasion of lung cancer. Immunoprecipitation showed that apoptin and AMPK could interact directly. Moreover, knockdown of AMPK significantly attenuated the inhibitory effect of Ad-apoptin on glycolysis, migration and invasion of A549 and NCI-H23 cells. Ad-apoptin can inhibit the growth of tumors in nude mice. Compared with the control group, Ad-apoptin had a significant inhibitory effect on AMPK knockdown tumors. The immunohistochemical results of tumor tissues were consistent with those in vitro. Collectively, Ad-apoptin targets AMPK and inhibits glycolysis, migration and invasion of lung cancer cells through the AMPK/mTOR signaling pathway. This suggests that Ad-apoptin may have therapeutic potential for lung cancer by targeting AMPK activation.

Guidelines for Regulated Cell Death Assays: A Systematic Summary, A Categorical Comparison, A Prospective

Over the past few years, the field of regulated cell death continues to expand and novel mechanisms that orchestrate multiple regulated cell death pathways are being unveiled. Meanwhile, researchers are focused on targeting these regulated pathways which are closely associated with various diseases for diagnosis, treatment, and prognosis. However, the complexity of the mechanisms and the difficulties of distinguishing among various regulated types of cell death make it harder to carry out the work and delay its progression. Here, we provide a systematic guideline for the fundamental detection and distinction of the major regulated cell death pathways following morphological, biochemical, and functional perspectives. Moreover, a comprehensive evaluation of different assay methods is critically reviewed, helping researchers to make a reliable selection from among the cell death assays. Also, we highlight the recent events that have demonstrated some novel regulated cell death processes, including newly reported biomarkers (e.g., non-coding RNA, exosomes, and proteins) and detection techniques.

Indolepropionic Acid, a Metabolite of the Microbiome, Has Cytostatic Properties in Breast Cancer by Activating AHR and PXR Receptors and Inducing Oxidative Stress

Oncobiotic transformation of the gut microbiome may contribute to the risk of breast cancer. Recent studies have provided evidence that the microbiome secretes cytostatic metabolites that inhibit the proliferation, movement, and metastasis formation of cancer cells. In this study, we show that indolepropionic acid (IPA), a bacterial tryptophan metabolite, has cytostatic properties. IPA selectively targeted breast cancer cells, but it had no effects on non-transformed, primary fibroblasts. In cell-based and animal experiments, we showed that IPA supplementation reduced the proportions of cancer stem cells and the proliferation, movement, and metastasis formation of cancer cells. These were achieved through inhibiting epithelial-to-mesenchymal transition, inducing oxidative and nitrosative stress, and boosting antitumor immune response. Increased oxidative/nitrosative stress was due to the IPA-mediated downregulation of nuclear factor erythroid 2-related factor 2 (NRF2), upregulation of inducible nitric oxide synthase (iNOS), and enhanced mitochondrial reactive species production. Increased oxidative/nitrosative stress led to cytostasis and reductions in cancer cell stem-ness. IPA exerted its effects through aryl hydrocarbon receptor (AHR) and pregnane X receptor (PXR) receptors. A higher expression of PXR and AHR supported better survival in human breast cancer patients, highlighting the importance of IPA-elicited pathways in cytostasis in breast cancer. Furthermore, AHR activation and PXR expression related inversely to cancer cell proliferation level and to the stage and grade of the tumor. The fecal microbiome's capacity for IPA biosynthesis was suppressed in women newly diagnosed with breast cancer, especially with stage 0. Bacterial indole biosynthesis showed correlation with lymphocyte infiltration to tumors in humans. Taken together, we found that IPA is a cytostatic bacterial metabolite, the production of which is suppressed in human breast cancer. Bacterial metabolites, among them, IPA, have a pivotal role in regulating the progression but not the initiation of the disease.

AMPK α1 Downregulates ROS Levels Through Regulating Trx Leading to Dysfunction of Apoptosis in Non-Small Cell Lung Cancer

Purpose

AMP-activated protein kinase α1 (AMPK α1) associates closely with cancers. However, the relationship between AMPK α1 and non-small cell lung cancer (NSCLC) is not fully understood. In this study, we aim to explore the role and mechanism of AMPK α1 in NSCLC initiation and progression.

Materials and Methods

A total of 165 clinical NSCLC specimens were included in the formalin-fixed and paraffin-embedded (FFPE) lung cancer tissue arrays. The expression levels of AMPK α1 and thioredoxin (Trx) in NSCLC cancer tissues and adjacent non-tumor lung tissues were measured through using immunohistochemistry. MTT assay was used to detect cell proliferation. Intracellular ROS levels were measured by using H2DCFDA reagent. Lentiviruses including LV-PRKAA1-RNAi, LV-PRKAA1 and a negative LV-control were used to infect A549 cells to modulate AMPK α1 expression in vitro. Immunoblotting was used to determine the modulation relationship between AMPK α1 and Trx. Log rank test and Kaplan–Meier survival analysis were performed to evaluate the significances of AMPK α1 and Trx expression levels on NSCLC patients’ prognoses.

Results

AMPK α1 was highly expressed in NSCLC cancer tissues and correlated with poor prognosis in patients with NSCLC. In A549 cells, overexpression of AMPK α1 promoted proliferation, suppressed ROS levels and inhibited apoptosis. Moreover, inhibition of AMPK α1 expression achieved the opposite effects. Trx was significantly overexpressed in NSCLC cancer tissues; furthermore, Trx expressed much more in cytoplasm when compared with cell nucleus. Trx expression levels were positively correlated with AMPK α1 expression levels in NSCLC tissues. AMPK α1 could regulate Trx in A549 cells. No significant correlations were observed between Trx expression variances and prognoses in NSCLC patients. Combination of AMPK α1 and Trx had no advantage in predicting prognoses of NSCLC patients.

Conclusion

These results suggest that AMPK α1 serves a carcinogenic role at least in part through the regulation of Trx expression, and thus represents a potential treatment target in patients with NSCLC.

Resveratrol inhibits the proliferation and induces the apoptosis in ovarian cancer cells via inhibiting glycolysis and targeting AMPK/mTOR signaling pathway

Aerobic glycolysis is an important metabolic rewiring in cancer cells to promote glucose uptake and lactate production, and targeting aerobic glycolysis becomes a promising therapeutic approach for cancer. Here we reported that a small polyphenol resveratrol exhibited profound anti-tumor efficacy on human ovarian cancer. Resveratrol markedly inhibited the proliferation, migration, and invasion of A2780 and SKOV3 ovarian cancer cells, while impaired glycolysis, and induced apoptosis in these cells. Exposure to resveratrol increased the expression and activation of AMPK and Caspase 3, and decreased the expression and activation of AMPK downstream kinase mTOR. Moreover, AMPK inhibitor Compound C significantly abolished the effects of resveratrol on the activation of AMPK and Caspase 3 and the inhibition of mTOR. In addition, in vivo data indicated that resveratrol suppressed ovarian cancer growth and liver metastasis in xenograft mouse model. In conclusion, our findings provide new insight into the mechanism underlying anticancer efficacy of resveratrol and help the utilization of resveratrol as a novel agent for the treatment of ovarian cancer.

Lithocholic acid, a bacterial metabolite reduces breast cancer cell proliferation and aggressiveness

Our study aimed at finding a mechanistic relationship between the gut microbiome and breast cancer. Breast cancer cells are not in direct contact with these microbes, but disease could be influenced by bacterial metabolites including secondary bile acids that are exclusively synthesized by the microbiome and known to enter the human circulation. In murine and bench experiments, a secondary bile acid, lithocholic acid (LCA) in concentrations corresponding to its tissue reference concentrations (< 1 μM), reduced cancer cell proliferation (by 10-20%) and VEGF production (by 37%), aggressiveness and metastatic potential of primary tumors through inducing mesenchymal-to-epithelial transition, increased antitumor immune response, OXPHOS and the TCA cycle. Part of these effects was due to activation of TGR5 by LCA. Early stage breast cancer patients, versus control women, had reduced serum LCA levels, reduced chenodeoxycholic acid to LCA ratio, and reduced abundance of the baiH (7α/β-hydroxysteroid dehydroxylase, the key enzyme in LCA generation) gene in fecal DNA, all suggesting reduced microbial generation of LCA in early breast cancer.

Predictive and preventive significance of AMPK activation on hepatocarcinogenesis in patients with liver cirrhosis

Metformin has been demonstrated to prevent hepatocellular carcinoma (HCC). Metformin acts mainly by phosphorylation of AMPK. However, the phosphorylation status of AMPK and its role in the prediction and prevention of HCC in cirrhotic patients remains unclear. The phosphorylation status of AMPK (Thr172) was determined by immunostaining in tissue microarrays of 426 cirrhotic liver tissues. Low expression of p-AMPK was observed in 94 (22.1%) cases. The median follow-up time was 87 months. HCC occurrence probability at 1/3/5/10 years after Hassab procedure was 3.1/9.6/13.8/30.6% in patients with p-AMPK low expression and 0/0.3/0.3/8% in patients with p-AMPK high expression, respectively. HCC occurrence risk was significantly higher in patients with p-AMPK low expression in univariable analysis (HR, 6.25; 95% CI: 3.36–11.60; P < 0.001) and multivariable analysis (HR, 6.0; 95% CI: 3.24–11.10; P < 0.001). An independent external cohort validated the significance of p-AMPK low expression. In addition, in vivo experiments demonstrated that AMPK activation status was negatively related to HCC occurrence and blocking autophagy by chloroquine counteracted the protective effect of AMPK phosphorylation. These results present novel insight into a critical predictive role of AMPK activation in hepatocarcinogenesis and AMPK activation seems to be a potential target for the prevention of hepatocellular carcinoma in patients with liver cirrhosis.

Repairing Mitochondrial Dysfunction in Disease

Mitochondria are essential organelles for many aspects of cellular homeostasis, including energy harvesting through oxidative phosphorylation. Alterations of mitochondrial function not only impact on cellular metabolism but also critically influence whole-body metabolism, health, and life span. Diseases defined by mitochondrial dysfunction have expanded from rare monogenic disorders in a strict sense to now also include many common polygenic diseases, including metabolic, cardiovascular, neurodegenerative, and neuromuscular diseases. This has led to an intensive search for new therapeutic and preventive strategies aimed at invigorating mitochondrial function by exploiting key components of mitochondrial biogenesis, redox metabolism, dynamics, mitophagy, and the mitochondrial unfolded protein response. As such, new findings linking mitochondrial function to the progression or outcome of this ever-increasing list of diseases has stimulated the discovery and development of the first true mitochondrial drugs, which are now entering the clinic and are discussed in this review.