A Trans-omics Mathematical Analysis Reveals Novel Functions of the Ornithine Metabolic Pathway in Cancer Stem Cells

A Rodent Model of Human-Dose-Equivalent 5-Fluorouracil: Toxicity in the Liver, Kidneys, and Lungs

5-Fluorouracil (5-FU) is a chemotherapy drug widely used to treat a range of cancer types, despite the recurrence of adverse reactions. Therefore, information on its side effects when administered at a clinically recommended dose is relevant. On this basis, we examined the effects of the 5-FU clinical treatment on the integrity of the liver, kidneys, and lungs of rats. For this purpose, 14 male Wistar rats were divided into treated and control groups and 5-FU was administered at 15 mg/kg (4 consecutive days), 6 mg/kg (4 alternate days), and 15 mg/kg on the 14th day. On the 15th day, blood, liver, kidney, and lung samples were collected for histological, oxidative stress, and inflammatory evaluations. We observed a reduction in the antioxidant markers and an increase in lipid hydroperoxides (LOOH) in the liver of treated animals. We also detected elevated levels of inflammatory markers, histological lesions, apoptotic cells, and aspartate aminotransferase. Clinical treatment with 5-FU did not promote inflammatory or oxidative alterations in the kidney samples; however, histological and biochemical changes were observed, including increased serum urea and uric acid. 5-FU reduces endogenous antioxidant defenses and increases LOOH levels in the lungs, suggesting oxidative stress. Inflammation and histopathological alterations were also detected. The clinical protocol of 5-FU promotes toxicity in the liver, kidneys, and lungs of healthy rats, resulting in different levels of histological and biochemical alterations. These results will be useful in the search for new adjuvants to attenuate the adverse effects of 5-FU in such organs.

Impact of One-Carbon Metabolism-Driving Epitranscriptome as a Therapeutic Target for Gastrointestinal Cancer

One-carbon (1C) metabolism plays a key role in biological functions linked to the folate cycle. These include nucleotide synthesis; the methylation of DNA, RNA, and proteins in the methionine cycle; and transsulfuration to maintain the redox condition of cancer stem cells in the tumor microenvironment. Recent studies have indicated that small therapeutic compounds affect the mitochondrial folate cycle, epitranscriptome (RNA methylation), and reactive oxygen species reactions in cancer cells. The epitranscriptome controls cellular biochemical reactions, but is also a platform for cell-to-cell interaction and cell transformation. We present an update of recent advances in the study of 1C metabolism related to cancer and demonstrate the areas where further research is needed. We also discuss approaches to therapeutic drug discovery using animal models and propose further steps toward developing precision cancer medicine.

One-carbon metabolism for cancer diagnostic and therapeutic approaches

Altered metabolism is critical for the rapid and unregulated proliferation of cancer cells; hence the requirement for an abundant source of nucleotides. One characteristic of this metabolic reprogramming is in one-carbon (1C) metabolism, which is particularly noteworthy for its role in DNA synthesis. Various forms of methylation are also noteworthy as they relate to cancer cell survival and proliferation. In recent years, 1C metabolism has received substantial attention for its role in cancer malignancy via these functions. Therefore, therapeutic inhibitors targeting 1C metabolism have been utilized as anticancer drugs. This review outlines the importance of 1C metabolism and its clinical application in cancer. Understanding 1C metabolism could aid the development of novel cancer diagnostic and therapeutic methods.

Methionine metabolism in health and cancer: a nexus of diet and precision medicine

Methionine uptake and metabolism is involved in a host of cellular functions including methylation reactions, redox maintenance, polyamine synthesis and coupling to folate metabolism, thus coordinating nucleotide and redox status. Each of these functions has been shown in many contexts to be relevant for cancer pathogenesis. Intriguingly, the levels of methionine obtained from the diet can have a large effect on cellular methionine metabolism. This establishes a link between nutrition and tumour cell metabolism that may allow for tumour-specific metabolic vulnerabilities that can be influenced by diet. Recently, a number of studies have begun to investigate the molecular and cellular mechanisms that underlie the interaction between nutrition, methionine metabolism and effects on health and cancer.

Significant epitranscriptomes in heterogeneous cancer

Precision medicine places significant emphasis on techniques for the identification of DNA mutations and gene expression by deep sequencing of gene panels to obtain medical data. However, other diverse information that is not easily readable using bioinformatics, including RNA modifications, has emerged as a novel diagnostic and innovative therapy owing to its multifunctional aspects. It is suggested that this breakthrough innovation might open new avenues for the elucidation of uncharacterized cancer cellular functions to develop more precise medical applications. The functional characteristics and regulatory mechanisms of RNA modifications, ie, the epitranscriptome (ETR), which reflects RNA metabolism, remains unclear, mainly due to detection methods being limited. Recent studies have revealed that N6‐methyl adenosine, the most common modification in mRNA in eukaryotes, is affected in various types of cancer and, in some cases, cancer stem cells, but also affects cellular responses to viral infections. The ETR can control cancer cell fate through mRNA splicing, stability, nuclear export, and translation. Here we report on the recent progress of ETR detection methods, and biological findings regarding the significance of ETR in cancer precision medicine.

Polyamine flux suppresses histone lysine demethylases and enhances ID1 expression in cancer stem cells

Cancer stem cells (CSCs) exhibit tumorigenic potential and can generate resistance to chemotherapy and radiotherapy. A labeled ornithine decarboxylase (ODC, a rate-limiting enzyme involved in polyamine [PA] biosynthesis) degradation motif (degron) system allows visualization of a fraction of CSC-like cells in heterogeneous tumor populations. A labeled ODC degradation motif system allowed visualization of a fraction of CSC-like cells in heterogeneous tumor populations. Using this system, analysis of polyamine flux indicated that polyamine metabolism is active in CSCs. The results showed that intracellular polyamines inhibited the activity of histone lysine 4 demethylase enzymes, including lysine-specific demethylase-1 (LSD1). Chromatin immunoprecipitation with Pol II antibody followed by massively parallel DNA sequencing, revealed the global enrichment of Pol II in transcription start sites in CSCs. Increase of polyamines within cells resulted in an enhancement of ID1 gene expression. The results of this study reveal details of metabolic pathways that drive epigenetic control of cancer cell stemness and determine effective therapeutic targets in CSCs.

Enzymes of the one-carbon folate metabolism as anticancer targets predicted by survival rate analysis

The significance of mitochondrial metabolism in cancer cells has recently been gaining attention. Among other findings, One-carbon folate metabolism has been reported to be closely associated with cellular characteristics in cancer. To study molecular targets for efficient cancer therapy, we investigated the association between the expressions of genes that code enzymes involved in one-carbon metabolism and survival rate of patients with adenocarcinomas of the colorectum and lung. Patients with high expression of genes that control the metabolic cycle of tetrahydrofolate (THF) in mitochondria, SHMT2, MTHFD2, and ALDH1L2, have a shorter overall survival rate compared with patients with low expression of these genes. Our results revealed that these genes could be novel and more promising anticancer targets than dihydrofolate reductase (DHFR), the current target of drug therapy linked with folate metabolism, suggesting the rationale of drug discovery in cancer medicine.

Plasma metabolic profiling on postoperative colorectal cancer patients with different traditional Chinese medicine syndromes

OBJECTIVES

This study aims to investigate the metabolic profiles of postoperative colorectal cancer (PCRC) patients with different traditional Chinese medicine (TCM) syndromes and to discuss the metabolic mechanism under PCRC progression and TCM syndrome classification.

METHODS

Fifty healthy controls (HC) and 70 PCRC patients, including 10 Dampness and heat syndrome (DHS), 33 Spleen deficiency syndrome (SDS), 19 Liver and kidney Yin deficiency syndrome (LKYDS) and 8 with non-TCM syndrome (NS) were enrolled. Plasma metabolic profiles were detected by Gas chromatography-mass spectrometry (GC-MS) and analyzed by principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA). Furthermore, pathway enrichment was analyzed based on KEGG and DAVID databases and metabolic network was constructed via metaboanalyst and cytoscape.

RESULTS

The top-3 metabolites with higher abundance in PCRC compared with HC were terephthalic acid (165.417-fold), ornithine (24.484-fold) and aminomalonic acid (21.346-fold). And the cholesterol (0.588-fold) level was decreased in PCRC. l-Alanine, 1, 2-ethanediamine, urea, glycerol, glycine, aminomalonic acid, creatinine and palmitic acid were specifically altered in the DHS, while d-tryptophan was exclusively changed in SDS, and l-proline, 1, 2, 3-propanetricarboxylic acid, d-galactose and 2-indolecarboxylic acids in LKYDS.

CONCLUSIONS

The plasma metabolic profiles were perturbed in PCRC patients. Increased levels of terephthalic acid might indicate high risk of relapse and elevated ornithine may contribute to the post-operational recovery or may raise the susceptibility to PCRC recurrence. The metabolic profiles of DHS, SDS, LKYDS and NS were almost separately clustered, indicating the possibility of explaining TCM syndromes classification using metabolomics. Furthermore, creatinine and aminomalonic acid alternation might correlate with the formation of DHS, while d-tryptophan may associate with SDS and d-galactose and 1, 2, 3-propanetricarboxylic acid may relate to LKYDS. As numbers of patients in each TCM syndrome are small, further study is needed to verify those results.

The one-carbon metabolism pathway highlights therapeutic targets for gastrointestinal cancer (Review)

After the initial use of anti-folates for treatment of malignancies, folate metabolism has emerged as a rational diagnostic and therapeutic target in gastrointestinal cancer. The one-carbon metabolic pathway, which comprises three critical reactions (i.e., folate and methionine cycles), underlies this effect in conjunction with the trans-sulfuration pathway. Understanding of the one-carbon metabolism pathway has served to unravel the link between the causes and effects of cancer phenotypes leading to several seminal discoveries such as that of diadenosine tri-phosphate hydrolase, microRNAs, 5-FU and, more recently, trifluridine. In the folate cycle, glycine and serine fuel the mitochondrial enzymes SHMT2, MTHFD2 and ALDH1L2, which play critical roles in the cancer survival and proliferation presumably through purine production. In the methionine cycle, S-adenocyl methionine serves hydrocarbons and polyamines that are critical for the epigenetic controls. The trans-sulfuration pathway is a critical component in the synthesis of glutathione, which is involved in the production of reactive oxygen species in cancer stem cells. Therefore, characterization of one-carbon metabolism is indispensable to the development of precision medicine in the context of cancer diagnostics and therapeutics. In the present study, we review the historical issues associated with one-carbon metabolism and highlight the recent advances in cancer research.