Regulation of gene expression by glycolytic and gluconeogenic enzymes.

Gene transcription and cell metabolism are two fundamental biological processes that mutually regulate each other. Upregulated or altered expression of glucose metabolic genes in glycolysis and gluconeogenesis is a major driving force of enhanced aerobic glycolysis in tumor cells. Importantly, glycolytic and gluconeogenic enzymes in tumor cells acquire moonlighting functions and directly regulate gene expression by modulating chromatin or transcriptional complexes. The mutual regulation between cellular metabolism and gene expression in a feedback mechanism constitutes a unique feature of tumor cells and provides specific molecular and functional targets for cancer treatment.

Flightless-I Blocks p62-Mediated Recognition of LC3 to Impede Selective Autophagy and Promote Breast Cancer Progression.

p62 is a receptor that facilitates selective autophagy by interacting simultaneously with cargoes and LC3 protein on the autophagosome to maintain cellular homeostasis. However, the regulatory mechanism(s) behind this process and its association with breast cancer remain to be elucidated. Here, we report that Flightless-I (FliI), a novel p62-interacting protein, promotes breast cancer progression by impeding selective autophagy. FliI was highly expressed in clinical breast cancer samples, and heterozygous deletion of FliI retarded the development of mammary tumors in PyVT mice. FliI induced p62-recruited cargoes into Triton X-100 insoluble fractions (TI) to form aggregates, thereby blocking p62 recognition of LC3 and hindering p62-dependent selective autophagy. This function of Flil was reinforced by Akt-mediated phosphorylation at Ser436 and inhibited by phosphorylation of Ulk1 at Ser64. Obstruction of autophagic clearance of p62-recruited cargoes by FliI was associated with the accumulation of oxidative damage on proteins and DNA, which could contribute to the development of cancer. Heterozygous knockout of FliI facilitated selectively autophagic clearance of aggregates, abatement of ROS levels, and protein oxidative damage, ultimately retarding mammary cancer progression. In clinical breast cancer samples, Akt-mediated phosphorylation of FliI at Ser436 negatively correlated with long-term prognosis, while Ulk1-induced FliI phosphorylation at Ser64 positively correlated with clinical outcome. Together, this work demonstrates that FliI functions as a checkpoint protein for selective autophagy in the crosstalk between FliI and p62-recruited cargoes, and its phosphorylation may serve as a prognostic marker for breast cancer.Significance: Flightless-I functions as a checkpoint protein for selective autophagy by interacting with p62 to block its recognition of LC3, leading to tumorigenesis in breast cancer.Cancer Res; 78(17); 4853-64. ©2018 AACR.

Nur77 suppresses hepatocellular carcinoma via switching glucose metabolism toward gluconeogenesis through attenuating phosphoenolpyruvate carboxykinase sumoylation.

Gluconeogenesis, an essential metabolic process for hepatocytes, is downregulated in hepatocellular carcinoma (HCC). Here we show that the nuclear receptor Nur77 is a tumour suppressor for HCC that regulates gluconeogenesis. Low Nur77 expression in clinical HCC samples correlates with poor prognosis, and a Nur77 deficiency in mice promotes HCC development. Nur77 interacts with phosphoenolpyruvate carboxykinase (PEPCK1), the rate-limiting enzyme in gluconeogenesis, to increase gluconeogenesis and suppress glycolysis, resulting in ATP depletion and cell growth arrest. However, PEPCK1 becomes labile after sumoylation and is degraded via ubiquitination, which is augmented by the p300 acetylation of ubiquitin-conjugating enzyme 9 (Ubc9). Although Nur77 attenuates sumoylation and stabilizes PEPCK1 via impairing p300 activity and preventing the Ubc9-PEPCK1 interaction, Nur77 is silenced in HCC samples due to Snail-mediated DNA methylation of the Nur77 promoter. Our study reveals a unique mechanism to suppress HCC by switching from glycolysis to gluconeogenesis through Nur77 antagonism of PEPCK1 degradation.

[Identification of tumor-associated proteins in laryngeal squamous cell carcinoma by proteomics].

OBJECTIVE: To establish two-dimensional electrophoresis profiles from human laryngeal squamous cell carcinoma tissue and paired normal tumor-adjacent mucosa epithelia tissue, and to identify differential expression proteins. METHODS: The total proteins of human laryngeal squamous carcinoma tissue and paired normal tumor-adjacent mucosa epithelia tissue were separated by immobilized pH gradient-based two-dimensional gel electrophoresis (2-DE). The differential expression proteins were analyzed using image analysis software, then identified using mass spectrometry and database searching. RESULTS: Well-resolved, reproducible 2-DE patterns of laryngeal squamous cell carcinoma and adjacent normal mucosa epithelial were obtained. Differential protein spots were defined as spots in 2-DE gels. Thirteen proteins were preliminarily identified, naming which 10 proteins were upregulated in laryngeal cancer tissue. Such as cofilin-1, nuclear body protein SP140, GRP94, HSP 90, GSTP1-1, superoxide dismutase [Mn], cyclophilin A, proteasome activator complex subunit 2, apolipoprotein A-I precursor, CaM-like protein and so on. There were 3 proteins downregulated in laryngeal cancer tissue, which were fatty acid-binding protein, calgranulin A and calgranulin B. CONCLUSIONS: Thirteen proteins which are associated with the tumorigenesis of the laryngeal squamous cell carcinoma were characterized. These extensive protein variations indicate that multiple protein molecules should be simultaneously targeted as an effective strategy to counter the disease. It is better for understanding of the oncogenesis and pathogenesis in a global way, which in turn is a basis-for the rational designs of diagnostic and therapeutic methods.

[Effect of preoperative intra-arterial chemotherapy on apoptosis and p53 expression of gastric cancer].

BACKGROUND & OBJECTIVE: Regional chemotherapy is charactized by a high drug concentration in tumor tissues and slight side-effects. Some significant histopathological changes were observed in the patients with gastric carcinoma treated by selective intra-arterial infusion chemotherapy before operation. The aim of this study was to investigate the effect of preoperative intra-arterial chemotherapy on apoptosis and p53 expression in human gastric cancer and its clinical significance. METHODS: The apoptosis was examined by terminal uridine deoxynucleotide nick end labeling (TUNEL) and the expression of p53 was detected with immunohistochemistry in 33 patients with gastric carcinoma pre- and post-chemotherapy respectively. RESULTS: Apoptosis index(AI) was significantly higher in the post-chemotherapeutic patients than in the pre-chemotherapeutic ones (19.29 +/- 6.48 versus 9.24 +/- 5.03, P < 0.01). In contrast, the positive expression rate of p53 was significantly lower, in the post-chemotherapeutic patients, than in the pre-chemotherapeutic ones(30.30% versus 54.55%, P < 0.05). In the post-chemotherapeutic patients, the droped group of p53 expression were strongly associated with a better clinical response(P < 0.05). CONCLUSIONS: Preoperative intra-arterial chemotherapy could enhance the apoptosis of gastric cancer cell, decrease the level of p53 expression and keep the patients for a longer survival.