bims-meluca 2020-07-05 papers

Front Oncol. 2020 ;10 807

Lactic Acidosis in the Presence of Glucose Diminishes Warburg Effect in Lung Adenocarcinoma Cells.

Prado-Garcia H, Campa-Higareda A, Romero-Garcia S.

Lactic acidosis (3 to 40 mM, pH < 6.9) is a condition found in solid tumors because tumor cells have a high rate of glucose consumption and lactate production even in the presence of oxygen; nevertheless, the microenvironment might still provide a sufficient glucose supply. Lactic acidosis has been proposed to shift metabolism from aerobic glycolysis toward oxidative phosphorylation (OXPHOS). We tested if lung tumor cells cultured under lactic acidosis shift their metabolism from glycolysis to OXPHOS by consuming extracellular lactate, increasing growth rate. We analyzed lung adenocarcinoma (A-549, A-427) cell lines and non-transformed fibroblast cells (MRC-5), which were cultured using RPMI-1640 medium initially containing lactate (2 mM) and glucose (10 mM), at pH 7.2 or 6.2 and oxygen tension 21% O2 (normoxia) or 2% O2 (hypoxia). We obtained growth curves, as well as glucose consumption and lactate production rates (measured during exponential growth) for each cell line. HIF-1α (Hypoxia-inducible factor 1 α), CS (citrate synthase) and AMPK (AMP-activated protein kinase) transcript levels were analyzed using RT-qPCR. By flow cytometry, we determined: (a) expression of glucose transporters (GLUT)1 and 4; (b) lactate transporters (MCT)1 and 4; (c) cell cycle profile, and (d) protein levels of HIF-1α, total and phosphorylated AMPK (pAMPK). Mitochondrial functionality was evaluated by measuring O2 consumption in tumor cells using polarography and a Clark-type electrode. Tumor and non-transformed cells used both aerobic glycolysis and OXPHOS for obtaining energy. As of 48 h of culture, lactate levels ranged from (4.5-14 mM), thus forming a lactic environment. Lactic acidosis diminished GLUT1/GLUT4 expression and glucose consumption in A-549, but not in A-427 cells, and induced differential expression of HIF-1α, AMPK, and CS transcripts. A-427 cells increased pAMPK and HIF-1α levels and shifted their metabolism increasing OXPHOS; thus supporting cell growth. Conversely, A-549 cells increased HIF-1α protein levels, but did not activate AMPK and diminished OXPHOS. A-549 cells survived by arresting cells in G1-phase. Our findings show that lactic acidosis diminishes Warburg effect in tumor cells, but this change does not necessarily promote a shift to OXPHOS. Hence, lung adenocarcinomas show a differential metabolic response even when they are under the same microenvironmental conditions.

Keywords: aerobic glycolysis; mitochondrial function; oxidative metabolism; tumor metabolic shift; tumor metabolic symbiosis

DOI: https://doi.org/10.3389/fonc.2020.00807

Onco Targets Ther. 2020 ;13 5967-5977

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

Gong D, Li Y, Wang Y, Chi B, Zhang J, Gu J, Yang J, Xu X, Hu S, Min L.

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.

Keywords: AMPK α1; ROS; apoptosis; non-small cell lung cancer

DOI: https://doi.org/10.2147/OTT.S236235

Clin Nutr. 2020 Jun 09. pii: S0261-5614(20)30287-9. [Epub ahead of print]

Feasibility of a multimodal intervention on malnutrition in patients with lung cancer during primary anti-neoplastic treatment.

Tobberup R, Carus A, Rasmussen HH, Falkmer UG, Jorgensen MG, Schmidt EB, Jensen NA, Mark EB, Delekta AM, Antoniussen CS, Bøgsted M, Holst M.

BACKGROUND: Wasting of body mass and skeletal muscle frequently develops in patients with cancer and is associated with impaired functional ability and poor clinical outcome and quality of life. This study aimed to evaluate the feasibility and explore the effect of a multimodal intervention targeting nutritional status in patients with non-small cell lung cancer receiving primary anti-neoplastic treatment. Additionally, predictive and prognostic factors of gaining skeletal muscle were explored.METHODS: This was a single-centre multimodal intervention trial using a historical control group. The multimodal intervention involved fish oil intake (2 g of eicosapentaenoic acid or docosahexaenoic acid daily), regular dietary counselling and unsupervised physical exercise twice weekly during the first three cycles of primary anti-neoplastic treatment. Feasibility was assessed through recruitment rate, completion rate and compliance rate with the intervention. Differences in skeletal muscle, body weight, and physical function between the intervention and historical control groups were analysed. Factors contributing to increased skeletal muscle were explored using univariate and multivariate ordinal logistic regression analyses.
RESULTS: The recruitment and completion rates were 0.48 (n = 59/123) and 0.80 (n = 46/59), respectively. The overall compliance rate with all five individual interventions was 0.60 (n = 28/47). The individual compliance rates were 0.81 (n = 38/47) with fish oil intake, 0.94 (n = 44/47) with energy intake, 0.98 (n = 46/47) with protein intake, 0.51 (n = 24/47) with resistance exercise and 0.57 (n = 27/47) with aerobic exercise. No mean differences in skeletal muscle, body weight, or physical function were found between the intervention and control groups. However, a larger proportion of patients in the intervention group gained skeletal muscle (p < 0.02). The identified contributing factors of muscle gain were weight gain (OR, 1.3; p = 0.01), adherence to treatment plan (OR, 4.6; p = 0.02), stable/partial response (OR, 3.3; p = 0.04) and compliance to the intervention (OR, 7.4; p = 0.01). Age, sex, tumour stage, performance status, treatment type and baseline cachexia did not predict muscle gain.
CONCLUSION: This three-dimensional intervention in patients with lung cancer undergoing primary anti-neoplastic treatment was feasible and increased the proportion of patients gaining skeletal muscle. Dietary counselling and fish oil use were useful strategies. The motivation for conducting unsupervised physical intervention was low. Clinical trials.gov identifier: NCT04161794.

Keywords: Cachexia; Dietary intervention; Exercise; Fish oil; Malignancy; Muscle; NSCLC

DOI: https://doi.org/10.1016/j.clnu.2020.05.050