LINC00365 functions as a tumor suppressor by inhibiting HIF-1α-mediated glucose metabolism reprogramming in breast cancer.

Long non-coding RNAs (lncRNAs) play an important role in regulating several physiological processes and have been implicated in several pathologies including cancer. LncRNAs have been found to regulate key cellular pathways involved in cancer development, and their aberrant expression plays critical roles in the onset or progression of disease. The role of lncRNAs in breast cancer (BC) has become a hot topic of research in recent years. We previously showed that LINC00365 inhibits BC survival. In the current study, based on the important role of energy metabolism and HIF-1α for tumor cell proliferation, we investigated the role and mechanism of the LINC00365/HIF-1α axis in affecting tumor growth through glycolysis using the breast cancer cell lines MCF-7 and HCC-1937. We found that LINC00365 inhibited BC cell proliferation. Furthermore, LINC00365 overexpression suppressed aerobic glycolysis in BC cells. RNA-sequencing identified hypoxia-inducible factor-1α (HIF-1α), which has been linked with glycolysis and upregulates glycolysis-related genes, as a potential target gene of LINC00365. Accordingly, we found that LINC00365 overexpression resulted in decreased expression of key glycolytic enzymes such as downstream hexokinase 2 (HK2), recombinant pyruvate kinase isozymes M2 (PKM2) and lactate dehydrogenase A (LDHA). Our results suggest that targeting LINC00365 may reverse the glucose metabolism pattern of BC and effectively inhibit BC survival both in vitro and in vivo.

Insight into the role of p62 in the cisplatin resistant mechanisms of ovarian cancer.

Cisplatin is a platinum-based first-line drug for treating ovarian cancer. However, chemotherapy tolerance has limited the efficacy of cisplatin for ovarian cancer patients. Research has demonstrated that cisplatin causes changes in cell survival and death signaling pathways through its interaction with macromolecules and organelles, which indicates that investigation into the DNA off-target effects of cisplatin may provide critical insights into the mechanisms underlying drug resistance. The multifunctional protein p62 works as a signaling hub in the regulation of pro-survival transcriptional factors NF-κB and Nrf2 and connects autophagy and apoptotic signals, which play important roles in maintaining cell homeostasis. In this review, we discuss the role of p62 in cisplatin resistance by exploring p62-associated signaling pathways based on current studies and our work. Insights into these resistance mechanisms may lead to more effective therapeutic strategies for ovarian cancer by targeting p62.

Autophagy-Induced HDAC6 Activity During Hypoxia Regulates Mitochondrial Energy Metabolism Through the ß-Catenin/COUP-TFII Axis in Hepatocellular Carcinoma Cells.

Hypoxia is one of the main driving forces that results in poor outcomes and drug resistance in hepatocellular carcinoma (HCC). As the critical cellular oxygen sensor, mitochondria respond to hypoxic stress by sending retrograde signals to the nucleus that initiate adaptive metabolic responses and maintain the survival of HCC cells. Increasing evidence suggested autophagy contributes to sustain mitochondrial metabolic and quality control. Understanding how mitochondria communicate with the nucleus and alter transcription may provide promising targets for HCC treatment. In this study, we found mitochondrial undergoes selective degradation by autophagy under hypoxia. Furthermore, autophagy-activated HDAC6 not only promoted the nuclear translocation of ß-catenin but also increased the affinity of ß-catenin to the transcription repressor chicken ovalbumin upstream promoter-transcription factor 2 (COUP-TF II), which suppressed mitochondrial oxidative phosphorylation-related genes transcription. Our data showed that autophagy served as a critical mediator of integrating mitochondrial energy metabolism and nuclear transcription. HDAC6 may be a potential target for reducing the survival of HCC cells by interrupting mitochondria-nucleus crosstalk.

Hypoxia-induced NAD+ interventions promote tumor survival and metastasis by regulating mitochondrial dynamics.

Hypoxia, an important feature of the tumor microenvironment, is responsible for the chemo-resistance and metastasis of malignant solid tumors. Recent studies indicated that mitochondria undergo morphological transitions as an adaptive response to maintain self-stability and connectivity under hypoxic conditions. NAD+ may not only provide reducing equivalents for biosynthetic reactions and in determining energy production, but also functions as a signaling molecule in mitochondrial dynamics regulation. In this review, we describe the upregulated KDAC deacetylase expression in the mitochondria and cytoplasm of tumor cells that results from sensing the changes in NAD+ to control mitochondrial dynamics and distribution, which is responsible for survival and metastasis in hypoxia.

Glycometabolic rearrangements--aerobic glycolysis in pancreatic cancer: causes, characteristics and clinical applications.

Pancreatic cancer is one of the most malignant tumors worldwide, and pancreatic ductal adenocarcinoma is the most common type. In pancreatic cancer, glycolysis is the primary way energy is produced to maintain the proliferation, invasion, migration, and metastasis of cancer cells, even under normoxia. However, the potential molecular mechanism is still unknown. From this perspective, this review mainly aimed to summarize the current reasonable interpretation of aerobic glycolysis in pancreatic cancer and some of the newest methods for the detection and treatment of pancreatic cancer. More specifically, we reported some biochemical parameters, such as newly developed enzymes and transporters, and further explored their potential as diagnostic biomarkers and therapeutic targets.

Bioinformatic Analysis of Circular RNA-Associated ceRNA Network Associated with Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and is associated with a high mortality rate and poor treatment efficacy. In an attempt to investigate the mechanisms involved in the pathogenesis of HCC, bioinformatic analysis and validation by qRT-PCR were performed. Three circRNA GEO datasets and one miRNA GEO dataset were selected for this purpose. Upon combined biological prediction, a total of 11 differentially expressed circRNAs, 15 differentially expressed miRNAs, and 560 target genes were screened to construct a circRNA-related ceRNA network. GO analysis and KEGG pathway analysis were performed for the 560 target genes. To further screen key genes, a protein-protein interaction network of the target genes was constructed using STRING, and the genes and modules with higher degree were identified by MCODE and CytoHubba plugins of Cytoscape. Subsequently, a module was screened out and subjected to GO enrichment analysis and KEGG pathway analysis. This module included eight genes, which were further screened using TCGA. Finally, UBE2L3 was selected as a key gene and the hsa_circ_0009910-miR-1261-UBE2L3 regulatory axis was established. The relative expression of the regulatory axis members was confirmed by qRT-PCR in 30 pairs of samples, including HCC tissues and adjacent nontumor tissues. The results suggested that hsa_circ_0009910, which was upregulated in HCC tissues, participates in the pathogenesis of HCC by acting as a sponge of miR-1261 to regulate the expression of UBE2L3. Overall, this study provides support for the possible mechanisms of progression in HCC.

Autophagy inhibitor chloroquine increases sensitivity to cisplatin in QBC939 cholangiocarcinoma cells by mitochondrial ROS.

The tumor cells have some metabolic characteristics of the original tissues, and the metabolism of the tumor cells is closely related to autophagy. However, the mechanism of autophagy and metabolism in chemotherapeutic drug resistance is still poorly understood. In this study, we investigated the role and mechanism of autophagy and glucose metabolism in chemotherapeutic drug resistance by using cholangiocarcinoma QBC939 cells with primary cisplatin resistance and hepatocellular carcinoma HepG2 cells. We found that QBC939 cells with cisplatin resistance had a higher capacity for glucose uptake, consumption, and lactic acid generation, and higher activity of the pentose phosphate pathway compared with HepG2 cells, and the activity of PPP was further increased after cisplatin treatment in QBC939 cells. It is suggested that there are some differences in the metabolism of glucose in hepatocellular carcinoma and cholangiocarcinoma cells, and the activation of PPP pathway may be related to the drug resistance. Through the detection of autophagy substrates p62 and LC3, found that QBC939 cells have a higher flow of autophagy, autophagy inhibitor chloroquine can significantly increase the sensitivity of cisplatin in cholangiocarcinoma cells compared with hepatocellular carcinoma HepG2 cells. The mechanism may be related to the inhibition of QBC939 cells with higher activity of the PPP, the key enzyme G6PDH, which reduces the antioxidant capacity of cells and increases intracellular ROS, especially mitochondrial ROS. Therefore, we hypothesized that autophagy and the oxidative stress resistance mediated by glucose metabolism may be one of the causes of cisplatin resistance in cholangiocarcinoma cells. It is suggested that according to the metabolism characteristics of tumor cells, inhibition of autophagy lysosome pathway with chloroquine may be a new route for therapeutic agents against cholangiocarcinoma.

ABT737 reverses cisplatin resistance by regulating ER-mitochondria Ca2+ signal transduction in human ovarian cancer cells.

Bcl-2, which belongs to the Bcl-2 family, is frequently overexpressed in various types of cancer cells and contributes to drug resistance. However, the function of Bcl-2 in cisplatin resistance in human ovarian cancer cells is not fully understood. In this study, we found that the pharmacological inhibitor ABT737 or genetic knockdown of Bcl-2 increased cisplatin cytotoxicity in cisplatin-resistant ovarian cancer cells. Additionally, treatment with ABT737 or Bcl-2 siRNA increased cisplatin-induced free Ca2+ levels in the cytosol and mitochondria, which increased endoplasmic reticulum (ER)-associated and mitochondria-mediated apoptosis. In addition, ABT737 or Bcl-2 siRNA increased the ER-mitochondria contact sites induced by cisplatin in cisplatin-resistant SKOV3/DDP ovarian cancer cells. Consistently with the in vitro results, ABT737 potently synergized with cisplatin in inhibiting the growth of human ovarian cancer xenografts in nude mice. Collectively, these results indicate that pharmacological inhibitors or genetic knockdown of Bcl-2 may be a potential strategy for improving cisplatin treatment of ovarian cancer.