METabolic adaptations in the tumor MYCroenvironment

Repressed miR-34a Expression Dictates the Cell Fate to Corneal Endothelium Failure

Purpose

To reveal the mechanism triggering the functional disparity between degenerated and non-degenerated corneal endothelium cells in the water efflux from corneal stroma to the anterior chamber.

Methods

The varied levels of the microRNA (miR)-34, miR-378, and miR-146 family in human corneal endothelium and cultured cells thereof were investigated using 3D-Gene Human miRNA Oligo Chips. Concomitantly, CD44, p53, c-Myc, matrix metalloprotease (MMP)-2 expression, and Ras homolog gene family member A (Rho A) activity was correlated to the expression intensities of these microRNAs, partly complemented with their altered expression levels with the transfection of the corresponding mimics and inhibitors. The levels of miRs were further associated with intracellular pH (pHi) and mitochondrial energy homeostasis.

Results

P53-inducible miR-34a/b repressed CD44 expression, and CD44 was repressed with the elevated c-Myc. The repressed miR-34a activated the CD44 downstream factors Rho A and MMP-2. MiR-34a mimics downregulated pHi, inducing the skewing of mitochondrial respiration to oxidative phosphorylation. The oxidative stress (H₂O₂) induced on human corneal endothelial cells, which repressed miR-34a/b expression, may account for the impaired signaling cascade to mitochondrial metabolic homeostasis necessary for an efficient water efflux from the corneal stroma.

Conclusions

The upregulated expression of CD44, through repressed miR-34a/b by reactive oxygen species and elevated c-Myc by oxidative stress, may impair mitochondrial metabolic homeostasis, leading to human corneal endothelial failure.

Single-Cell Profiling Reveals Heterogeneity of Primary and Lymph Node Metastatic Tumors and Immune Cell Populations and Discovers Important Prognostic Significance of CCDC43 in Oral Squamous Cell Carcinoma

Although substantial progress has been made in biological research and clinical treatment in recent years, the clinical prognosis of oral squamous cell carcinoma (OSCC) is still not satisfactory. Tumor immune microenvironment (TIME) is a potential target, which plays an essential role in the response of anti-tumor immunity and immunotherapy. In this study, we used scRNA-seq data, revealing the heterogeneity of TIME between metastatic and primary site. We found that in the metastatic site, the content of cytotoxic T cells and classical activated macrophages (M1 macrophages) increases significantly, while alternately activated macrophages (M2 macrophages) and inflammatory cancer-associated fibroblasts (iCAFs) decrease, which may be due to the increased immunogenicity of OSCC cells in the metastatic site and the changes in some signal pathways. We also found that iCAFs may recruit alternately activated macrophages (M2 macrophages) by secreting CXCL12. Then, we described a regulatory network for communication between various TIME cells centered on OSCC cells, which can help to clarify the possible mechanism of lymph node metastasis in OSCC cells. By performing pseudotime trajectory analysis, we found that the expression CCDC43 is upregulated in more advanced OSCC cells and is an independent prognostic factor for poor living conditions. Other than this, the high expression of CCDC43 may impair the antitumor immunity of the human body and promote the metastasis of OSCC cells. Our research provides a profound insight into the immunological study of OSCC and an essential resource for future drug discovery.

Metabolic Reprogramming: A Friend or Foe to Cancer Therapy?

Drug resistance is a major cause of cancer treatment failure, effectively driven by processes that promote escape from therapy-induced cell death. The mechanisms driving evasion of apoptosis have been widely studied across multiple cancer types, and have facilitated new and exciting therapeutic discoveries with the potential to improve cancer patient care. However, an increasing understanding of the crosstalk between cancer hallmarks has highlighted the complexity of the mechanisms of drug resistance, co-opting pathways outside of the canonical "cell death" machinery to facilitate cell survival in the face of cytotoxic stress. Rewiring of cellular metabolism is vital to drive and support increased proliferative demands in cancer cells, and recent discoveries in the field of cancer metabolism have uncovered a novel role for these programs in facilitating drug resistance. As a key organelle in both metabolic and apoptotic homeostasis, the mitochondria are at the forefront of these mechanisms of resistance, coordinating crosstalk in the event of cellular stress, and promoting cellular survival. Importantly, the appreciation of this role metabolism plays in the cytotoxic response to therapy, and the ability to profile metabolic adaptions in response to treatment, has encouraged new avenues of investigation into the potential of exploiting metabolic addictions to improve therapeutic efficacy and overcome drug resistance in cancer. Here, we review the role cancer metabolism can play in mediating drug resistance, and the exciting opportunities presented by imposed metabolic vulnerabilities.

Metabolites Interrogation in Cell Fate Decision of Cultured Human Corneal Endothelial Cells

Purpose

Aiming to clarify the metabolic interrogation in cell fate decision of cultured human corneal endothelial cells (cHCECs).

Methods

To analyze the metabolites in the culture supernatants (CS), 34 metabolome measurements were carried out for mature differentiated and a variety of cHCECs with cell state transition through a facility service. Integrated proteomics research for cell lysates by liquid chromatography−tandem mass spectrometry (LC-MS/MS) was performed for 3 aliquots of each high-quality or low-quality cHCEC subpopulations (SP). The investigations for the focused genes involved in cHCEC metabolism were performed by using DAVID and its options “KEGG_PATHWAY.”

Results

The clusters of metabolites coincided well with the distinct content of CD44−/+ SPs. Both secreted pyruvic acid and lactic acid in the CS were negatively correlated with the content of high-quality SPs. Lactic acid and pyruvic acid in the CS exhibited the positive correlation with that of Ile, Leu, and Ser, whereas the negative correlation was with glutamine. Platelet-derived growth factor-ββ in the CS negatively correlated with lactic acid in CS, indicating indirectly the positive correlation with the content of CD44−/+ SPs. Upregulated glycolytic enzymes and influx of glutamine to the tricarboxylic acid cycle may be linked with a metabolic rewiring converting oxidative metabolism in mature differentiated CD44−/+SPs into a glycolytic flux-dependent state in immature SPs with cell state transition.

Conclusions

The findings suggest that the cell fate decision of cHCECs may be dictated at least partly through metabolic rewiring.

Cancer metabolism in space and time: Beyond the Warburg effect

Altered metabolism in cancer cells is pivotal for tumor growth, most notably by providing energy, reducing equivalents and building blocks while several metabolites exert a signaling function promoting tumor growth and progression. A cancer tissue cannot be simply reduced to a bulk of proliferating cells. Tumors are indeed complex and dynamic structures where single cells can heterogeneously perform various biological activities with different metabolic requirements. Because tumors are composed of different types of cells with metabolic activities affected by different spatial and temporal contexts, it is important to address metabolism taking into account cellular and biological heterogeneity. In this review, we describe this heterogeneity also in metabolic fluxes, thus showing the relative contribution of different metabolic activities to tumor progression according to the cellular context. This article is part of a Special Issue entitled Mitochondria in Cancer, edited by Giuseppe Gasparre, Rodrigue Rossignol and Pierre Sonveaux.

The role of tumor metabolism as a driver of prostate cancer progression and lethal disease: results from a nested case-control study

Background

Understanding the biologic mechanisms underlying the development of lethal prostate cancer is critical for improved therapeutic and prevention strategies. In this study we explored the role of tumor metabolism in prostate cancer progression using mRNA expression profiling of seven metabolic pathways; fatty acid metabolism, glycolysis/gluconeogenesis, oxidative phosphorylation, pentose phosphate, purine metabolism, pyrimidine metabolism and the tricarboxylic acid cycle.

Methods

The study included 404 men with archival formalin-fixed, paraffin-embedded prostate tumor tissue from the prospective Health Professionals Follow-up Study and Physicians’ Health Study. Lethal cases (n = 113) were men who experienced a distant metastatic event or died of prostate cancer during follow-up. Non-lethal controls (n = 291) survived at least 8 years post-diagnosis without metastases. Of 404 men, 202 additionally had matched normal tissue (140 non-lethal, 62 lethal). Analyses compared expression levels between tumor and normal tissue, by Gleason grade and by lethal status. Secondary analyses considered the association with biomarkers of cell proliferation, apoptosis and angiogenesis.

Results

Oxidative phosphorylation and pyrimidine metabolism were identified as the most dysregulated pathways in lethal tumors (p < 0.007), and within these pathways, a number of novel differentially expressed genes were identified including POLR2K and APT6V1A. The associations were tumor specific as there was no evidence any pathways were altered in the normal tissue of lethal compared to non-lethal cases.

Conclusions

The results suggest prostate cancer progression and lethal disease are associated with alterations in key metabolic signaling pathways. Pathways supporting proliferation appeared to be of particular importance in prostate tumor aggressiveness.

Electronic supplementary material

The online version of this article (doi:10.1186/s40170-016-0161-9) contains supplementary material, which is available to authorized users.

Multimodality Imaging Identifies Distinct Metabolic Profiles In Vitro and In Vivo

The study of alterations of tumor metabolism should allow the identification of new targets for innovative anticancer strategies. Metabolic alterations are generally established in vitro, and conclusions are often extrapolated to the in vivo situation without further tumor metabolic phenotyping. To highlight the key role of microenvironment on tumor metabolism, we studied the response of glycolytic and oxidative tumor models to metabolic modulations in vitro and in vivo. MDA-MB-231 and SiHa tumor models, characterized in vitro as glycolytic and oxidative, respectively, were studied. Theoretically, when passing from a hypoxic state to an oxygenated state, a Warburg phenotype should conserve a glycolytic metabolism, whereas an oxidative phenotype should switch from glycolytic to oxidative metabolism (Pasteur effect). This challenge was applied in vitro and in vivo to evaluate the impact of different oxic conditions on glucose metabolism. ¹⁸F-fluorodeoxyglucose uptake, lactate production, tumor oxygenation, and metabolic fluxes were monitored in vivo using positron emission tomography, microdialysis, electron paramagnetic resonance imaging, and ¹³C-hyperpolarizated magnetic resonance spectroscopy, respectively. In vitro, MDA-MB-231 cells were glycolytic under both hypoxic and oxygenated conditions, whereas SiHa cells underwent a metabolic shift after reoxygenation. On the contrary, in vivo, the increase in tumor oxygenation (induced by carbogen challenge) led to a similar metabolic shift in glucose metabolism in both tumor models. The major discordance in metabolic patterns observed in vitro and in vivo highlights that any extrapolation of in vitro metabolic profiling to the in vivo situation should be taken cautiously and that metabolic phenotyping using molecular imaging is mandatory in vivo.

Environment Impacts the Metabolic Dependencies of Ras-Driven Non-Small Cell Lung Cancer

Cultured cells convert glucose to lactate, and glutamine is the major source of tricarboxylic acid (TCA)-cycle carbon, but whether the same metabolic phenotype is found in tumors is less studied. We infused mice with lung cancers with isotope-labeled glucose or glutamine and compared the fate of these nutrients in tumor and normal tissue. As expected, lung tumors exhibit increased lactate production from glucose. However, glutamine utilization by both lung tumors and normal lung was minimal, with lung tumors showing increased glucose contribution to the TCA cycle relative to normal lung tissue. Deletion of enzymes involved in glucose oxidation demonstrates that glucose carbon contribution to the TCA cycle is required for tumor formation. These data suggest that understanding nutrient utilization by tumors can predict metabolic dependencies of cancers in vivo. Furthermore, these data argue that the in vivo environment is an important determinant of the metabolic phenotype of cancer cells.

Oestrogen-related receptors in breast cancer: control of cellular metabolism and beyond

Oestrogen-related receptors (ERRs) are orphan nuclear receptors that were initially investigated in breast cancer because of their structural relationship to oestrogen receptors. Recent data have shown that the ERRs control vast gene networks that are involved in glycolysis, glutaminolysis, oxidative phosphorylation, nutrient sensing and biosynthesis pathways. In the context of breast cancer, the ERRs affect cellular metabolism in a manner that promotes a Warburg-like phenotype. The ERRs also modulate breast cancer cell metabolism, growth and proliferation through the regulation of key oncoproteins. We discuss the value but also the implications of the complexity of targeting the ERRs for the development of cancer therapeutics.