Tumor metabolic crosstalk and immunotherapy

Tumor cells must resist the host's immune system while maintaining growth under harsh conditions of acidity and hypoxia, which indicates that tumors are more robust than normal tissue. Immunotherapeutic agents have little effect on solid tumors, mostly because of the tumor density and the difficulty of penetrating deeply into the tissue to achieve the theoretical therapeutic effect. Various therapeutic strategies targeting the tumor microenvironment (TME) have been developed. Immunometabolic disorders play a dominant role in treatment resistance at both the TME and host levels. Understanding immunometabolic factors and their treatment potential may be a way forward for tumor immunotherapy. Here, we summarize the metabolism of substances that affect tumor progression, the crosstalk between the TME and immunosuppression, and some potential tumor-site targets. We also summarize the progress and challenges of tumor immunotherapy.

Quantifying Adhesion of Inflammatory Cells to the Endothelium In Vitro

We present a simple and quantitative assay system that accurately models human endothelium by use of primary human umbilical vein endothelial cells (HUVECs) in cell culture plates coated with gelatin, a matrix that mimics basal lamina, the matrix that is tightly associated with the vascular endothelium and is critical for its proper function. We describe using this system to quantitatively measure adhesion of the inflammatory cells - monocytic THP-1 cell line to the HUVEC monolayer. The THP-1 cells are fluorescently labeled which allows to quantify the number of the fluorescent THP-1 cells adhering to the endothelium under a microscope and the level of florescence - a quantitative measure of the number of adhering fluorescent THP-1 cells using a fluorescent plate reader. After optimization, we were able to detect increased adhesion of the THP-1 cells to the endothelium in response to the inflammatory cytokine TNFα in a dose-dependent manner like what has been observed in vivo.

Delta-5-desaturase: A novel therapeutic target for cancer management

•

D5D is an independent prognostic factor in cancer.

•

D5D aggravates cancer progression via mediating AA/PGE₂ production from DGLA.

•

AA/PGE₂ promotes cancer progression via regulating the tumor microenvironment.

•

Inhibition of D5D redirects COX-2 catalyzed DGLA peroxidation, producing 8-HOA.

•

8-HOA suppress cancer by regulating proliferation, apoptosis, and metastasis.

Delta-5 desaturase (D5D) is a rate-limiting enzyme that introduces double-bonds to the delta-5 position of the n-3 and n-6 polyunsaturated fatty acid chain. Since fatty acid metabolism is a vital factor in cancer development, several recent studies have revealed that D5D activity and expression could be an independent prognostic factor in cancers. However, the mechanistic basis of D5D in cancer progression is still controversial. The classical concept believes that D5D could aggravate cancer progression via mediating arachidonic acid (AA)/prostaglandin E₂ production from dihomo-γ-linolenic acid (DGLA), resulting in activation of EP receptors, inflammatory pathways, and immunosuppression. On the contrary, D5D may prevent cancer progression through activating ferroptosis, which is iron-dependent cell death. Suppression of D5D by RNA interference and small-molecule inhibitor has been identified as a promising anti-cancer strategy. Inhibition of D5D could shift DGLA peroxidation pattern from generating AA to a distinct anti-cancer free radical byproduct, 8-hydroxyoctanoic acid, resulting in activation of apoptosis pathway and simultaneously suppression of cancer cell survival, proliferation, migration, and invasion. Hence, understanding the molecular mechanisms of D5D on cancer may therefore facilitate the development of novel therapeutical applications. Given that D5D may serve as a promising target in cancer, in this review, we provide an updated summary of current knowledge on the role of D5D in cancer development and potentially useful therapeutic strategies.

Label-free quantitative identification of abnormally ubiquitinated proteins as useful biomarkers for human lung squamous cell carcinomas

BACKGROUND

Ubiquitination is an important molecular event in lung squamous cell carcinoma (LSCC), which currently is mainly studied in nonsmall cell lung carcinoma cell models but lacking of ubiquitination studies on LSCC tissues. Here, we presented the ubiquitinated protein profiles of LSCC tissues to explore ubiquitination-involved molecular network alterations and identify abnormally ubiquitinated proteins as useful biomarkers for predictive, preventive, and personalized medicine (PPPM) in LSCC.

METHODS

Anti-ubiquitin antibody-based enrichment coupled with LC-MS/MS was used to identify differentially ubiquitinated proteins (DUPs) between LSCC and control tissues, followed by integrative omics analyses to identify abnormally ubiquitinated protein biomarkers for LSCC.

RESULTS

Totally, 400 DUPs with 654 ubiquitination sites were identified,, and motifs A-X (1/2/3)-K* were prone to be ubiquitinated in LSCC tissues. Those DUPs were involved in multiple molecular network systems, including the ubiquitin-proteasome system (UPS), cell metabolism, cell adhesion, and signal transduction. Totally, 44 hub molecules were revealed by protein-protein interaction network analysis, followed by survival analysis in TCGA database (494 LSCC patients and 20,530 genes) to obtain 18 prognosis-related mRNAs, of which the highly expressed mRNAs VIM and IGF1R were correlated with poorer prognosis, while the highly expressed mRNA ABCC1 was correlated with better prognosis. VIM-encoded protein vimentin and ABCC1-encoded protein MRP1 were increased in LSCC, which were all associated with poor prognosis. Proteasome-inhibited experiments demonstrated that vimentin and MRP1 were degraded through UPS. Quantitative ubiquitinomics found ubiquitination level was decreased in vimentin and increased in MRP1 in LSCC. These findings showed that the increased vimentin in LSCC might be derived from its decreased ubiquitination level and that the increased MRP1 in LSCC might be derived from its protein synthesis > degradation. GSEA and co-expression gene analyses revealed that VIM and MRP1 were involved in multiple crucial biological processes and pathways. Further, TRIM2 and NEDD4L were predicted as E3 ligases to regulate ubiquitination of vimentin and MRP1, respectively.

CONCLUSION

These findings revealed ubiquitinomic variations and molecular network alterations in LSCC, which is in combination with multiomics analysis to identify ubiquitination-related biomarkers for in-depth insight into the molecular mechanism and therapeutic targets and for prediction, diagnosis, and prognostic assessment of LSCC.

Imaging Cancer Angiogenesis and Metastasis in a Zebrafish Embryo Model

Tumor angiogenesis and metastasis are key steps of cancer progression. In vitro and animal model studies have contributed to partially elucidating the mechanisms involved in these processes and in developing therapies. Besides the improvements in fundamental research and the optimization of therapeutic regimes, cancer still remains a major health threatening condition and therefore the development of new models is needed. The zebrafish is a powerful tool to study tumor angiogenesis and metastasis, because it allows the visualization of fluorescently labelled tumor cells inducing vessel remodeling, disseminating and invading surrounding tissues in a whole transparent embryo. The embryo model has also been used to address the contribution of the tumor stroma in sustaining tumor angiogenesis and spreading. Simultaneously, new anti-angiogenic drugs and compounds affecting malignant cell survival and migration can be tested by simply adding the compound into the water of living embryos. Therefore the zebrafish model offers the opportunity to gain more knowledge on cancer angiogenesis and metastasis in vivo with the final aim of providing new translational insights into therapeutic approaches to help patients.