bims-meluca 2021-01-03 papers

Cell Metab. 2020 Dec 17. pii: S1550-4131(20)30662-8. [Epub ahead of print]

Non-canonical Glutamate-Cysteine Ligase Activity Protects against Ferroptosis.

Yun Pyo Kang, Andrea Mockabee-Macias, Chang Jiang, Aimee Falzone, Nicolas Prieto-Farigua, Everett Stone, Isaac S Harris, Gina M DeNicola.

Cysteine is required for maintaining cellular redox homeostasis in both normal and transformed cells. Deprivation of cysteine induces the iron-dependent form of cell death known as ferroptosis; however, the metabolic consequences of cysteine starvation beyond impairment of glutathione synthesis are poorly characterized. Here, we find that cystine starvation of non-small-cell lung cancer cell lines induces an unexpected accumulation of γ-glutamyl-peptides, which are produced due to a non-canonical activity of glutamate-cysteine ligase catalytic subunit (GCLC). This activity is enriched in cell lines with high levels of NRF2, a key transcriptional regulator of GCLC, but is also inducible in healthy murine tissues following cysteine limitation. γ-glutamyl-peptide synthesis limits the accumulation of glutamate, thereby protecting against ferroptosis. These results indicate that GCLC has a glutathione-independent, non-canonical role in the protection against ferroptosis by maintaining glutamate homeostasis under cystine starvation.

Keywords: GCLC; NRF2; cysteine; cystine; ferroptosis; glutamate; γ-glutamyl

DOI: https://doi.org/10.1016/j.cmet.2020.12.007

Lung Cancer. 2020 Dec 04. pii: S0169-5002(20)30721-2. [Epub ahead of print]152 58-65

The relationship between body-mass index and overall survival in non-small cell lung cancer by sex, smoking status, and race: A pooled analysis of 20,937 International lung Cancer consortium (ILCCO) patients.

INTRODUCTION: The relationship between Body-Mass-Index (BMI) and lung cancer prognosis is heterogeneous. We evaluated the impact of sex, smoking and race on the relationship between BMI and overall survival (OS) in non-small-cell-lung-cancer (NSCLC).
METHODS: Data from 16 individual ILCCO studies were pooled to assess interactions between BMI and the following factors on OS: self-reported race, smoking status and sex, using Cox models (adjusted hazard ratios; aHR) with interaction terms and adjusted penalized smoothing spline plots in stratified analyses.
RESULTS: Among 20,937 NSCLC patients with BMI values, females = 47 %; never-smokers = 14 %; White-patients = 76 %. BMI showed differential survival according to race whereby compared to normal-BMI patients, being underweight was associated with poor survival among white patients (OS, aHR = 1.66) but not among black patients (aHR = 1.06; pinteraction = 0.02). Comparing overweight/obese to normal weight patients, Black NSCLC patients who were overweight/obese also had relatively better OS (pinteraction = 0.06) when compared to White-patients. BMI was least associated with survival in Asian-patients and never-smokers. The outcomes of female ever-smokers at the extremes of BMI were associated with worse outcomes in both the underweight (pinteraction<0.001) and obese categories (pinteraction = 0.004) relative to the normal-BMI category, when compared to male ever-smokers.
CONCLUSION: Underweight and obese female ever-smokers were associated with worse outcomes in White-patients. These BMI associations were not observed in Asian-patients and never-smokers. Black-patients had more favorable outcomes in the extremes of BMI when compared to White-patients. Body composition in Black-patients, and NSCLC subtypes more commonly seen in Asian-patients and never-smokers, may account for differences in these BMI-OS relationships.

Keywords: Body mass index; Interaction; Lung cancer; Obesity

DOI: https://doi.org/10.1016/j.lungcan.2020.11.029

Cancer Manag Res. 2020 ;12 13195-13206

TRIB3 Promotes Lung Adenocarcinoma Progression via an Enhanced Warburg Effect.

Yutong Xing, Peng Luo, Rui Hu, Duanduan Wang, Gang Zhou, Jie Jiang.

Background: The pseudokinase Tribbles 3 (TRIB3) is involved in many cellular processes and various cancers. In recent years, the importance of metabolic transformation in the maintenance of malignant tumors has become increasingly prominent. Abnormal metabolism of cancer cells is considered a hallmark of cancer. However, the exact role and molecular mechanism of TRIB3 in lung adenocarcinoma (LUAD) cell reprogramming is largely unknown.
Methods: The oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) of cells were examined with a Seahorse XF Extracellular Flux Analyzer. In vitro and in vivo RT-qPCR, Western blotting, and functional assays were performed to explore the functional roles of TRIB3 in LUAD.
Results: In the present study, we demonstrated that TRIB3 is remarkably upregulated in LUAD cell lines as well as tissues. TRIB3 knockdown significantly inhibited LUAD cell growth and suppressed LUAD cell invasion, while TRIB3 overexpression conferred the opposite effects. Moreover, silencing TRIB3 suppressed the tumorigenesis and metastatic ability of LUAD cells. Mechanistically, we demonstrated that silencing TRIB3 significantly impaired aerobic glycolysis ability in LUAD cells. Furthermore, our data indicated that TRIB3 knockdown decreased hypoxia-inducible factor (HIF)1α levels and targeted the glycolytic genes regulated by HIF1α.
Conclusion: Together, our findings revealed a previously unappreciated function of TRIB3 in cancer cell metabolism and tumor progression, illustrating that TRIB3 could be considered a valuable therapeutic target for LUAD patients.

Keywords: HIF1α; LUAD; TRIB3; aerobic glycolysis

DOI: https://doi.org/10.2147/CMAR.S287956

Mol Cancer Res. 2020 Dec 30. pii: molcanres.0579.2020. [Epub ahead of print]

The Ubiquitin Specific Protease USP18 Promotes Lipolysis, Fatty Acid Oxidation and Lung Cancer Growth.

Xi Liu, Yun Lu, Zibo Chen, Xiuxia Liu, Weiguo Hu, Lin Zheng, Yulong Chen, Jonathan M Kurie, Mi Shi, Lisa Maria Mustachio, Thorkell Andresson, Stephen Fox, Jason Roszik, Masanori Kawakami, Sarah Freemantle, Ethan Dmitrovsky.

Ubiquitin specific protease18 (USP18), previously known as UBP43, is the Interferon-Stimulated Gene 15 (ISG15) deconjugase. USP18 removes ISG15 from substrate proteins. This study reports that USP18 null mice (versus wild-type mice) exhibited lower lipolysis rates, altered fat to body weight ratios and cold sensitivity. USP18 is a regulator of lipid and fatty acid metabolism. Prior work established that USP18 promotes lung tumorigenesis. We sought to learn if this occurs through altered lipid and fatty acid metabolism. Loss of USP18 repressed adipose triglyceride lipase (ATGL) expression; gain of USP18 expression upregulated ATGL in lung cancer cells. The E1-like ubiquitin activating enzyme (UBE1L) promoted ISG15-conjugation of ATGL and destabilization. Immunoprecipitation assays confirmed that ISG15 covalently conjugates to ATGL. Protein expression of thermogenic regulators was examined in brown fat of USP18 null versus wild-type mice. Uncoupling Protein 1 (UCP1) was repressed in USP18 null fat. Gain of USP18 expression augmented UCP1 protein via reduced ubiquitination. Gain of UCP1 expression in lung cancer cell lines enhanced cellular proliferation. UCP1 knock-down inhibited proliferation. Beta-hydroxybutyrate colorimetric assays performed after gain of UCP1 expression revealed increased cellular fatty acid beta-oxidation, augmenting fatty acid beta-oxidation in seahorse assays. Combined USP18, ATGL and UCP1 profiles were interrogated in The Cancer Genome Atlas (TCGA). Intriguingly, lung cancers with increased USP18, ATGL and UCP1 expression had an unfavorable survival. These findings reveal that USP18 is a pharmacologic target that controls fatty acid metabolism. Implications: USP18 is an antineoplastic target that affects lung cancer fatty acid metabolism.

DOI: https://doi.org/10.1158/1541-7786.MCR-20-0579

Front Oncol. 2020 ;10 559568

Monoacylglycerol Lipase Knockdown Inhibits Cell Proliferation and Metastasis in Lung Adenocarcinoma.

Hao Zhang, Wei Guo, Fan Zhang, Renda Li, Yang Zhou, Fei Shao, Xiaoli Feng, Fengwei Tan, Jie Wang, Shugeng Gao, Yibo Gao, Jie He.

Abnormal metabolism is one of the hallmarks of cancer cells. Monoacylglycerol lipase (MGLL), a key enzyme in lipid metabolism, has emerged as an important regulator of tumor progression. In this study, we aimed to characterize the role of MGLL in the development of lung adenocarcinoma (LUAD). To this end, we used tissue microarrays to evaluate the expression of MGLL in LUAD tissue and assessed whether the levels of this protein are correlated with clinicopathological characteristics of LUAD. We found that the expression of MGLL is higher in LUAD samples than that in adjacent non-tumor tissues. In addition, elevated MGLL expression was found to be associated with advanced tumor progression and poor prognosis in LUAD patients. Functional studies further demonstrated that stable short hairpin RNA (shRNA)-mediated knockdown of MGLL inhibits tumor proliferation and metastasis, both in vitro and in vivo, and mechanistically, our data indicate that MGLL regulates Cyclin D1 and Cyclin B1 in LUAD cells. Moreover, we found that knockdown of MGLL suppresses the expression of matrix metalloproteinase 14 (MMP14) in A549 and H322 cells, and in clinical samples, expression of MMP14 is significantly correlated with MGLL expression. Taken together, our results indicate that MGLL plays an oncogenic role in LUAD progression and metastasis and may serve as a potential biomarker for disease prognosis and as a target for the development of personalized therapies.

Keywords: lung adenocarcinoma; matrix metalloproteinase 14; metastasis; monoacylglycerol lipase; prognosis; proliferation

DOI: https://doi.org/10.3389/fonc.2020.559568

Exp Oncol. 2020 12;42(4): 270-276

Plasminogen/plasmin affects expression of glycolysis regulator TIGAR and induces autophagy in lung adenocarcinoma A549 cells.

A A Tykhomyrov, V S Nedzvetsky, C A Aĝca, M M Guzyk, V V Korsa, T V Grinenko.

Pericellular plasmin generation triggers apoptosis/anoikis in normal adherent cells. However, cancer cells are notoriously resistant to anoikis, enabling metastasis and new tumor growth beyond their original environment. Autophagy can be a major contributor to anoikis resistance in cancer.
AIM: To investigate if protective autophagy can be induced in lung adenocarcinoma cells in response to plasminogen treatment.
MATERIALS AND METHODS: Human lung adenocarcinoma A549 cells were incubated with Glu-plasminogen (0.1-1.0 µM) for 24 h. Pericellular plasmin activity was monitored spectrophotometrically by a cleavage of the specific chromogenic- substrate S-2251. Cell survival was assessed by 3-[4,5-dimethyl thiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT)-test. Degradation of fibronectin, levels of autophagy markers (beclin-1 and light chain 3 (LC3)) and glycolysis regulator (TIGAR) were evaluated by western blot. Intracellular localization of LC-3 was visualized by immunocytochemistry.
RESULTS: It was shown that plasminogen is converted into plasmin on the surface of adenocarcinoma cells in a dose-dependent manner. Plasmin disrupted cellular adhesive contacts resulting in cell detachment. A549 cells did not loss their viability after plasminogen treatment for 24 h, while 1.0 µM plasminogen was cytotoxic for non-transformed fibroblasts. Plasminogen 0.1, 0.5, and 1.0 µM induced 7.08-, 5.18-, and 3.78-fold elevation of TIGAR expression (p < 0.05), respectively. Enhanced TIGAR expression indicates switch on pentose phosphate pathway, protection against oxidative stress to prevent apoptosis, facilitation of DNA repair and the degradation of their own organelles (autophagy). Exposure of adenocarcinoma cells to plasminogen in concentrations of 0.1 and 0.5 µM caused 1.74- and 2.19-fold elevation of beclin-1 expression vs untreated cells (p < 0.05), respectively. Unlike K1-3 fragment, plasminogen treatment (0.1-0.5 µM) resulted in increased expression of LC3-I and stimulated rapid conversion of LC3-I to LC3-II. Up-regulation of beclin-1 levels and enhanced LC3-I/II conversion in plasminogen-treated A549 cells are the hallmarks of autophagy induction. According to immunocytochemistry data, increased LC3 puncta and autophagosome formation after exposure to plasminogen could reflect autophagy activation.
CONCLUSIONS: Therefore, we showed stimulation of prosurvival signals and induction of autophagy in plasminogen-treated adenocarcinoma cells rendering them resistant to apoptosis/anoikis. Based on the obtained data, autophagy has a great potential for novel targets that affect cancer cell death, in addition to the current cytotoxic agents.