bims-meluca 2019-08-18 papers

Onco Targets Ther. 2019 ;12 5835-5848

Protein kinase C-iota-mediated glycolysis promotes non-small-cell lung cancer progression.

Liu L, Lei B, Wang L, Chang C, Yang H, Liu J, Huang G, Xie W.

Purpose: To determine whether protein kinase C-iota (PKC-iota) is associated with glucose metabolism in non-small-cell lung cancer (NSCLC) and whether its regulatory effect on metabolic and biological changes observed in NSCLC can be mediated by glucose transporter 1 (GLUT1).Patients and methods: Forty-five NSCLC patients underwent combined 18F-fludeoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET/CT) before surgery, and another eighty-one NSCLC patients were followed-up for 1-91 months after tumor resection. The rate of glucose metabolism in NSCLC was quantified by measuring the maximum standardized uptake value (SUVmax) by 18F-FDG PET/CT. PKC-iota and GLUT1 in NSCLC were detected by immunostaining. In vitro, PKC-iota was knocked down, whereas GLUT1 was silenced with or without PKC-iota overexpression to identify the role of PKC-iota in glycolysis. Spearman's rank correlation coefficient was used in the correlation analysis. Kaplan-Meier analysis was used to assess survival duration.
Results: There was a positive relationship between PKC-iota expression and SUVmax in NSCLC (r=0.649, P<0.001). PKC-iota expression also showed a positive relationship with GLUT1 in NSCLC tissues (r=0.686, P<0.001). Patients whose NSCLC tissues highly co-expressed PKC-iota and GLUT1 had worse prognosis compared with patients without high co-expression of PKC-iota and GLUT1. In vitro, PKC-iota silencing significantly decreased the expression of GLUT1 and inhibited glucose uptake and glycolysis; c-Myc silencing restrained PKC-iota-mediated GLUT1 elevation; GLUT1 knockdown remarkably suppressed PKC-iota-mediated glycolysis and cell growth.
Conclusion: In NSCLC, the rate of glucose metabolism was positively correlated with PKC-iota expression. PKC-iota increased glucose accumulation and glycolysis by upregulating c-Myc/GLUT1 signaling and is thus involved in tumor progression.

Keywords: 18F-fludeoxyglucose; glucose transporter 1; glycolysis; non-small-cell lung cancer; protein kinase C-iota

DOI: https://doi.org/10.2147/OTT.S207211

Cancer Res. 2019 Aug 15. pii: canres.2086.2018. [Epub ahead of print]

ERBB3 and IGF1R signaling are required for Nrf2-dependent growth in KEAP1-mutant lung cancer.

Mutations in KEAP1 and NFE2L2 (encoding the protein Nrf2) are prevalent in both adenocarcinoma and squamous subtypes of non-small cell lung cancer. The consequence of these mutations is stabilized Nrf2 and chronic induction of several Nrf2 target genes. Here, downregulation of Nrf2 resulted in modest growth inhibition of cells growing in 2D; this was more pronounced in cell lines expressing mutant KEAP1. In contrast, downregulation of Nrf2 caused almost complete regression of established KEAP1-mutant tumors in mice, with little effect on wildtype (WT) KEAP1 tumors. The strong dependency on Nrf2 could be recapitulated in certain anchorage-independent growth environments, and was not prevented by excess extracellular glutathione. Using CRISPR screening we identified alternative pathways critical for Nrf2-dependent growth in KEAP1-mutant cell lines, including the redox proteins thioredoxin and peroxiredoxin, as well as growth factor receptors IGF1R and ERBB3. IGF1R inhibition was effective in KEAP1 mutant cells compared to WT, especially under conditions of anchorage-independent growth. These results point to addiction of KEAP1-mutant tumor cells to Nrf2, and suggest that inhibition of Nrf2 or discrete druggable Nrf2 target genes such as IGF1R could be an effective therapeutic strategy for disabling these tumors.

DOI: https://doi.org/10.1158/0008-5472.CAN-18-2086

Oncogene. 2019 Aug 15.

The nuclear hypoxia-regulated NLUCAT1 long non-coding RNA contributes to an aggressive phenotype in lung adenocarcinoma through regulation of oxidative stress.

Lung cancer is the leading cause of cancer death worldwide, with poor prognosis and a high rate of recurrence despite early surgical removal. Hypoxic regions within tumors represent sources of aggressiveness and resistance to therapy. Although long non-coding RNAs (lncRNAs) are increasingly recognized as major gene expression regulators, their regulation and function following hypoxic stress are still largely unexplored. Combining profiling studies on early-stage lung adenocarcinoma (LUAD) biopsies and on A549 LUAD cell lines cultured in normoxic or hypoxic conditions, we identified a subset of lncRNAs that are both correlated with the hypoxic status of tumors and regulated by hypoxia in vitro. We focused on a new transcript, NLUCAT1, which is strongly upregulated by hypoxia in vitro and correlated with hypoxic markers and poor prognosis in LUADs. Full molecular characterization showed that NLUCAT1 is a large nuclear transcript composed of six exons and mainly regulated by NF-κB and NRF2 transcription factors. CRISPR-Cas9-mediated invalidation of NLUCAT1 revealed a decrease in proliferative and invasive properties, an increase in oxidative stress and a higher sensitivity to cisplatin-induced apoptosis. Transcriptome analysis of NLUCAT1-deficient cells showed repressed genes within the antioxidant and/or cisplatin-response networks. We demonstrated that the concomitant knockdown of four of these genes products, GPX2, GLRX, ALDH3A1, and PDK4, significantly increased ROS-dependent caspase activation, thus partially mimicking the consequences of NLUCAT1 inactivation in LUAD cells. Overall, we demonstrate that NLUCAT1 contributes to an aggressive phenotype in early-stage hypoxic tumors, suggesting it may represent a new potential therapeutic target in LUADs.

DOI: https://doi.org/10.1038/s41388-019-0935-y

Cell Rep. 2019 Aug 13. pii: S2211-1247(19)30924-6. [Epub ahead of print]28(7): 1860-1878.e9

p63 and SOX2 Dictate Glucose Reliance and Metabolic Vulnerabilities in Squamous Cell Carcinomas.

Squamous cell carcinoma (SCC), a malignancy arising across multiple anatomical sites, is responsible for significant cancer mortality due to insufficient therapeutic options. Here, we identify exceptional glucose reliance among SCCs dictated by hyperactive GLUT1-mediated glucose influx. Mechanistically, squamous lineage transcription factors p63 and SOX2 transactivate the intronic enhancer cluster of SLC2A1. Elevated glucose influx fuels generation of NADPH and GSH, thereby heightening the anti-oxidative capacity in SCC tumors. Systemic glucose restriction by ketogenic diet and inhibiting renal glucose reabsorption with SGLT2 inhibitor precipitate intratumoral oxidative stress and tumor growth inhibition. Furthermore, reduction of blood glucose lowers blood insulin levels, which suppresses PI3K/AKT signaling in SCC cells. Clinically, we demonstrate a robust correlation between blood glucose concentration and worse survival among SCC patients. Collectively, this study identifies the exceptional glucose reliance of SCC and suggests its candidacy as a highly vulnerable cancer type to be targeted by systemic glucose restriction.

Keywords: GLUT1; SGLT2; SOX2; glucose restriction; ketogenic diet; p63; squamous cell carcinoma

DOI: https://doi.org/10.1016/j.celrep.2019.07.027

Clin Cancer Res. 2019 Aug 13. pii: clincanres.0433.2019. [Epub ahead of print]

The folate pathway inhibitor pemetrexed pleiotropically enhances effects of cancer immunotherapy.

PURPOSE: Combination strategies leveraging chemotherapeutic agents and immunotherapy have held the promise as a method to improve benefit to cancer patients. However, most chemotherapies have detrimental effects on immune homeostasis and differ in their ability to induce immunogenic cell death. The approval of pemetrexed and carboplatin with anti-PD-1 (pembrolizumab) for treatment of non-small cell lung cancer, represents the first approved chemotherapy and immunotherapy combination. Although the clinical data suggests a positive interaction between pemetrexed-based chemotherapy and immunotherapy, the underlying mechanism remains unknown.EXPERIMENTAL DESIGN: Mouse tumor models (MC38, Colon26) and high-content biomarker studies (flow cytometry, Quantigene Plex and nCounter gene expression analysis) were deployed to obtain insights into the mechanistic rationale behind the efficacy observed with pemetrexed/anti-PD-L1 combination. Immunogenic cell death (ICD) in tumor cell lines was assessed by calreticulin and HMGB-1 immunoassays, and metabolic function of primary T cells was evaluated by Seahorse analysis.
RESULTS: Pemetrexed treatment alone increased T cell activation in mouse tumors in vivo, and robustly induced ICD in mouse tumor cells and exerted T cell-intrinsic effects exemplified by augmented mitochondrial function and enhanced T cell activation in vitro Increased anti-tumor efficacy and pronounced inflamed/immune activation were observed when Pemetrexed was combined with anti-PD-L1.
CONCLUSIONS: Pemetrexed augments systemic intra-tumor immune responses through tumor intrinsic mechanisms including immunogenic cell death, T cell-intrinsic mechanisms enhancing mitochondrial biogenesis leading to increased T cell infiltration/activation along with modulation of innate immune pathways, significantly enhanced in combination with PD-1 pathway blockade.

DOI: https://doi.org/10.1158/1078-0432.CCR-19-0433