Metabolic reprogramming of the premalignant colonic mucosa is an early event in carcinogenesis

The selective sponging of miRNAs by OIP5-AS1 regulates metabolic reprogramming of pyruvate in adenoma-carcinoma transition of human colorectal cancer

RNA interactomes and their diversified functionalities have recently benefited from critical methodological advances leading to a paradigm shift from a conventional conception on the regulatory roles of RNA in pathogenesis. However, the dynamic RNA interactomes in adenoma-carcinoma sequence of human CRC remain unexplored. The coexistence of adenoma, cancer, and normal tissues in colorectal cancer (CRC) patients provides an appropriate model to address this issue. Here, we adopted an RNA in situ conformation sequencing technology for mapping RNA-RNA interactions in CRC patients. We observed large-scale paired RNA counts and identified some unique RNA complexes including multiple partners RNAs, single partner RNAs, non-overlapping single partner RNAs. We focused on the antisense RNA OIP5-AS1 and found that OIP5-AS1 could sponge different miRNA to regulate the production of metabolites including pyruvate, alanine and lactic acid. Our findings provide novel perspectives in CRC pathogenesis and suggest metabolic reprogramming of pyruvate for the early diagnosis and treatment of CRC.

Analysis of the relationship between GLUT family in the progression and immune infiltration of head and neck squamous carcinoma

Head and neck squamous cell carcinoma (HNSCC) causes much health and economic burden, and the therapeutic results must be improved. Glucose metabolism is an essential component of tumor metabolism and is instrumental in its development. Glucose transporter types (GLUTs) can uptake glucose from the extracellular matrix (ECM), regulating cellular metabolism in several cancers. However, the function of different GLUT proteins in HNSCC remains unclear. To clarify the role of GLUTs in HNSCC, several open-access online databases (Oncomine, GEPIA, Kaplan-Meier, cBioPortal, GeneMANIA, and TIMER) were used to evaluate the differential expression, clinical significance, genetic alteration, and relative immune cell infiltration. The expression of GLUTs was detected in clinical patient samples by immunohistochemistry. The mRNA level of SLC2A1/3 significantly increased in HNSCC, while SLC2A4 reduced. SLC2A3 was related to the advanced clinical stage and short overall survival (OS) in HNSCC. Also, higher SLC2A1/2 mRNA expression was related to shorter OS in HNSCC patients. The expression of GLUTs was related to diverse immune cells, including B cells, CD4+ T cells, CD8+ T cells, dendritic cells (DCs), macrophages, and Treg cells in HNSCC. Moreover, the high expression of GLUTs was demonstrated by immunohistochemistry in patient tissues. GLUTs might have a potential role in HNSCC's progression and development. Therefore, the current findings might offer a novel perception for selecting GLUT family prognostic markers and treatment for HNSCC patients.

The essential molecular requirements for the transformation of normal cells into established cancer cells, with implications for a novel anti-cancer agent

BACKGROUND

Normal adult mammalian cells can respond to oncogenic somatic mutations by committing suicide through a well-described, energy dependent process termed apoptosis. Cancer cells avoid oncogene promoted apoptosis. Oncogenic somatic mutations are widely acknowledged to be the cause of the relentless unconstrained cell proliferation which characterises cancer. But how does the normal cell with the very first oncogenic mutation survive to proliferate without undergoing apoptosis?

NEW FINDINGS

The phenomena of malignant transformation by somatic mutation, apoptosis, aneuploidy, aerobic glycolysis and Cdk4 upregulation in carcinogenesis have each been extensively discussed separately in the literature but an overview explaining how they may be linked at the initiation of the cancer process has not previously proposed.

CONCLUSION

A hypothesis is presented to explain how in addition to the initial oncogenic mutation, the expression of certain key normal genes is, counter-intuitively, also required for successful malignant transformation from a normal cell to a cancer cell. The hypothesis provides an explanation for how the cyclic amphiphilic peptide HILR-056, derived from peptides with homology to a hexapeptide in the C-terminal region of Cdk4, kill cancer cells but not normal cell by necrosis rather than apoptosis.

Distinct Signatures of Tumor-Associated Microbiota and Metabolome in Low-Grade vs. High-Grade Dysplastic Colon Polyps: Inference of Their Role in Tumor Initiation and Progression

According to the driver-passenger model for colorectal cancer (CRC), the tumor-associated microbiota is a dynamic ecosystem of bacterial species where bacteria with carcinogenic features linked to CRC initiation are defined as "drivers", while opportunistic bacteria colonizing more advanced tumor stages are known as "passengers". We reasoned that also gut microbiota-associated metabolites may be differentially enriched according to tumor stage, and be potential determinants of CRC development. Thus, we characterized the mucosa- and lumen-associated microbiota (MAM and LAM, respectively) and mucosa-associated metabolites in low- vs. high-grade dysplastic colon polyps from 78 patients. We show that MAM, obtained with a new biopsy-preserving approach, and LAM differ in composition and α/β-diversity. By stratifying patients for polyp histology, we found that bacteria proposed as passengers by previous studies colonized high-grade dysplastic adenomas, whereas driver taxa were enriched in low-grade polyps. Furthermore, we report altered "mucosa-associated metabolite" levels in low- vs. high-grade groups. Integrated microbiota-metabolome analysis suggests the involvement of the gut microbiota in the production and consumption of these metabolites. Altogether, our findings support the involvement of bacterial species and associated metabolites in CRC mucosal homeostasis in a tumor-stage-specific manner. These distinct signatures may be used to distinguish low-grade from high-grade dysplastic polyps.

Stromal Changes in Colon Blastomogenesis Associated with Development of Hypoxia in the Foci of Dysplasia

We studied the features of reaction of the colon stromal cells (lymphohistiocytic population, fibroblasts, and blood vessels) to the appearance and progression of dysplasia in the colon epithelium against the background of increasing ischemia in the colon mucosa. The morphological material from 92 patients treated for benign processes and colon cancer in 2002-2016 was examined. Common histological methods and a complex immunohistochemical staining were used. The stromal cells of the colon mucosa, mainly lymphohistiocytic cells, undergo certain quantitative changes specific for each type of cells during progression of dysplasia and aggravation of ischemia in the mucosa. Some cells, e.g. plasma cells, presumably contribute to tissue hypoxia in the stroma. Most stromal cells, except interdigitating S100⁺ dendritic cells and CD10⁺ fibroblasts, decreased at the stage of grave dysplasia and cancer in situ. Low effectiveness of the immune defense can be partly explained by impairment of the function of stromal cells as a result of hypoxia in the microenvironment.

Metabolism-Related Gene Expression in Circulating Tumor Cells from Patients with Early Stage Non-Small Cell Lung Cancer

Simple Summary

In the present study, the expression of three Metabolism-Related Enzymes (MRGs) that are related to glucose and pyruvate metabolism, in parallel with glucose and monocarboxylate transporter expression (HK2, MCT1, PHGDH), was studied in CTCs isolated from the peripheral blood of early stage NSCLC patients at different timepoints. The expression levels of all tested MRGs decreased in CTCs one month after surgery, but a significant increase was noticed at the time of relapse for PHGDH and MCT1 only. An overexpression of MRGs was observed at a high frequency in the CTCs isolated from early NSCLC patients, thereby supporting the role of MRGs in metastatic processes. The glycolytic and mesenchymal subpopulation of CTCs was significantly predominant compared to CTCs that wereglycolytic but not mesenchymal-like. Our data indicate that MRGs merit further evaluation through large and well-defined cohort studies.

Abstract

Purpose: Metabolic reprogramming is now characterized as one of the core hallmarks of cancer, and it has already been shown that the altered genomic profile of metabolically rewired cancer cells can give valuable information. In this study, we quantified three Metabolism-Related Gene (MRG) transcripts in the circulating tumor cells (CTCs) of early stage NSCLC patients and evaluated their associations with epithelial and EMT markers. Experimental Design: We first developed and analytically validated highly sensitive RT-qPCR assays for the quantification of HK2, MCT1 and PHGDH transcripts, and further studied the expression of MRGs in CTCs that were isolated using a size-dependent microfluidic device (Parsortix, Angle) from the peripheral blood of: (a) 46 NSCLC patients at baseline, (b) 39/46 of these patients one month after surgery, (c) 10/46 patients at relapse and (d) 10 pairs of cancerous and adjacent non-cancerous FFPE tissues from the same NSCLC patients. Epithelial and EMT markers were also evaluated. Results: MCT1 and HK2 were differentially expressed between HD and NSCLC patients. An overexpression of MCT1 was detected in 15/46 (32.6%) and 3/10 (30%) patients at baseline and at progression disease (PD), respectively, whereas an overexpression of HK2 was detected in 30.4% and 0% of CTCs in the same group of samples. The expression levels of all tested MRGs decreased in CTCs one month after surgery, but a significant increase was noticed at the time of relapse for PHGDH and MCT1 only. The expression levels of HK2 and MCT1 were associated with the overexpression of mesenchymal markers (TWIST-1 and VIM). Conclusion: An overexpression of MRGs was observed at a high frequency in the CTCs isolated from early NSCLC patients, thereby supporting the role of MRGs in metastatic processes. The glycolytic and mesenchymal subpopulation of CTCs was significantly predominant compared to CTCs that were glycolytic but not mesenchymal-like. Our data indicate that MRGs merit further evaluation through large and well-defined cohort studies.

β-Boswellic Acid Suppresses Breast Precancerous Lesions via GLUT1 Targeting-Mediated Glycolysis Inhibition and AMPK Pathway Activation

Breast carcinoma is a multistep progressive disease. Precancerous prevention seems to be crucial. β-Boswellic acid (β-BA), the main component of the folk medicine Boswellia serrata (B. serrata), has been reported to be effective in various diseases including tumors. In this work, we demonstrated that β-BA could inhibit breast precancerous lesions in rat disease models. Consistently, β-BA could suppress proliferation and induce apoptosis on MCF-10AT without significantly influencing MCF-10A. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that β-BA may interfere with the metabolic pathway. Metabolism-related assays showed that β-BA suppressed glycolysis and reduced ATP production, which then activated the AMPK pathway and inhibited the mTOR pathway to limit MCF-10AT proliferation. Further molecular docking analysis suggested that GLUT1 might be the target of β-BA. Forced expression of GLUT1 could rescue the glycolysis suppression and survival limitation induced by β-BA on MCF-10AT. Taken together, β-BA could relieve precancerous lesions in vivo and in vitro through GLUT1 targeting-induced glycolysis suppression and AMPK/mTOR pathway alterations. Here, we offered a molecular basis for β-BA to be developed as a promising drug candidate for the prevention of breast precancerous lesions.

Pyruvate kinase M1 regulates butyrate metabolism in cancerous colonocytes

Colorectal cancer (CRC) cells shift metabolism toward aerobic glycolysis and away from using oxidative substrates such as butyrate. Pyruvate kinase M1/2 (PKM) is an enzyme that catalyzes the last step in glycolysis, which converts phosphoenolpyruvate to pyruvate. M1 and M2 are alternatively spliced isoforms of the Pkm gene. The PKM1 isoform promotes oxidative metabolism, whereas PKM2 enhances aerobic glycolysis. We hypothesize that the PKM isoforms are involved in the shift away from butyrate oxidation towards glycolysis in CRC cells. Here, we find that PKM2 is increased and PKM1 is decreased in human colorectal carcinomas as compared to non-cancerous tissue. To test whether PKM1/2 alter colonocyte metabolism, we created a knockdown of PKM2 and PKM1 in CRC cells to analyze how butyrate oxidation and glycolysis would be impacted. We report that butyrate oxidation in CRC cells is regulated by PKM1 levels, not PKM2. Decreased butyrate oxidation observed through knockdown of PKM1 and PKM2 is rescued through re-addition of PKM1. Diminished PKM1 lowered mitochondrial basal respiration and decreased mitochondrial spare capacity. We demonstrate that PKM1 suppresses glycolysis and inhibits hypoxia-inducible factor-1 alpha. These data suggest that reduced PKM1 is, in part, responsible for increased glycolysis and diminished butyrate oxidation in CRC cells.

Exploration of the typical features of tubulovillous adenoma using in-depth quantitative proteomics analysis

This present study aimed to explore the typical protein features of tubulovillous adenoma (TVA) using proteomic and bioinformatic analyses. Tandem mass tag (TMT)-based quantitative proteomic analyses were conducted on normal mucosa, tubular adenoma, TVA and adenocarcinoma tissues. We identified 5,665 proteins categorized into seven clusters based on Pearson’s correlation analysis. The bioinfomatic analysis showed mitochondrial and metabolism-related events were typical characteristics of TVA and mitochondrial-, ribosome- and matrisome-related biological processes may contribute to carcinogenesis. PLOD3 was identified as a key protein associated with the malignant potential of TVA and promoted the viability of adenoma organoids. The Cancer Genome Atlas (TCGA) analysis revealed PLOD3 as a risk factor for disease-free and overall survival. Furthermore, the PLOD3 expression correlated negatively with the abundance of B cells, CD8 + T cells, CD4 + T cells, neutrophils, macrophages and myeloid dendritic cells. In conclusion, enhanced metabolic and mitochondrial reprogramming are typical features of TVA, and PLOD3 might be related to the “immune desert” phenotype and contribute to TVA tumorigenesis and colorectal cancer development.

Cancer-Associated Mutations in Normal Colorectal Mucosa Adjacent to Sporadic Neoplasia

INTRODUCTION:

Colorectal cancer arises in a multistep process of carcinogenesis from normal mucosa. The earliest precursor might be a morphologically inconspicuous precancerous field, harboring cancer-associated mutations.

METHODS:

We systematically analyzed genetic alterations in 77 tissue samples from 30 patients with sporadic colorectal neoplasms (18 large adenomas and 12 adenocarcinomas) and matched adjacent normal mucosa (N = 30), as well as normal rectal tissue (N = 17). We profiled mutations associated with colorectal cancer by targeted sequencing of 46 genetic loci using 157 custom amplicons and a median depth of 42,655 reads per loci.

RESULTS:

Multiple mutations were found in colorectal neoplasms, most frequently in APC, KRAS, and TP53. In a subgroup of 11 of 30 patients, alterations were also detected in non-neoplastic mucosa. These mutations were divergent from those in matched neoplasms. The total alteration count and the allele frequency of mutations were higher in neoplasms compared with those in adjacent tissues. We found that younger patients (≤70 years) are less likely affected by mutations in non-neoplastic mucosa than older patients (>70 years, P = 0.013), although no association was found for other variables, including type, location and differentiation of neoplasia, and previous history of polyps.

DISCUSSION:

Our data show that cancer-associated mutations can be found in non-neoplastic tissues in a subgroup of patients with colorectal neoplasms. Further studies are needed to specify the risk of occurrence and recurrence of neoplasia in this patient population.

Genetic Mutations and Non-Coding RNA-Based Epigenetic Alterations Mediating the Warburg Effect in Colorectal Carcinogenesis

Colorectal cancer (CRC) development is a gradual process defined by the accumulation of numerous genetic mutations and epigenetic alterations leading to the adenoma-carcinoma sequence. Despite significant advances in the diagnosis and treatment of CRC, it continues to be a leading cause of cancer-related deaths worldwide. Even in the presence of oxygen, CRC cells bypass oxidative phosphorylation to produce metabolites that enable them to proliferate and survive-a phenomenon known as the "Warburg effect". Understanding the complex glucose metabolism in CRC cells may support the development of new diagnostic and therapeutic approaches. Here we discuss the most recent findings on genetic mutations and epigenetic modulations that may positively or negatively regulate the Warburg effect in CRC cells. We focus on the non-coding RNA (ncRNA)-based epigenetics, and we present a perspective on the therapeutic relevance of critical molecules and ncRNAs mediating the Warburg effect in CRC cells. All the relevant studies were identified and assessed according to the genes and enzymes mediating the Warburg effect. The findings summarized in this review should provide a better understanding of the relevance of genetic mutations and the ncRNA-based epigenetic alterations to CRC pathogenesis to help overcome chemoresistance.

Histone deacetylase inhibitor induced pVHL-independent degradation of HIF-1α and hierarchical quality control of pVHL via chaperone system

The mortality rate of ovarian cancer is increasing and the role of hypoxia inducible factor-1α (HIF-1α) in tumor progression has been confirmed. von Hippel-Lindau tumor suppressor protein (pVHL) binds HIF-1α and mediates proteasome degradation of HIF-1α. Besides, histone deacetylase inhibitor (HDACi) mitigates tumor growth via targeting HIF-1α, whereas underlying mechanism still requires investigation. In this research, we exposed ovarian cancer cell lines OV-90 and SKOV-3 to escalating concentrations of HDACi LBH589. As a result, cell viability was significantly suppressed and expression of HIF-1α was remarkably reduced along with decreased levels of signal molecules, including phosphoinositide 3-kinase (PI3K) and glycogen synthase kinase 3β (GSK3β) (P = 0.000). Interestingly, pVHL was expressed in a notably declining tendency (P = 0.000). Chaperone heat shock protein-70 (HSP70) was expressed in an ascending manner, whereas expression of chaperonin TCP-1α was reduced clearly (P = 0.000). Besides, co-inhibition of pVHL plus HDAC did not contribute to a remarkable difference in HIF-1α expression as compared with single HDAC inhibition. Furthermore, both cell lines were transfected with plasmids of VHL plus VHL binding protein-1 (VBP-1). Consequently, the expression of HIF-1α as well as lactate dehydrogenase-A (LDHA) was remarkably decreased (P = 0.000). These findings indicate HDACi may repress expression of HIF-1α via inhibiting PI3K and GSK3β and promote degradation of HIF-1α via HSP70, independent of pVHL. Additionally, a sophisticated network of HDAC and chaperones may involve in pVHL quality control.

Glucose and fatty acid metabolism involved in the protective effect of metformin against ulipristal-induced endometrial changes in rats

Ulipristal acetate (UPA) is effective in the treatment of uterine fibroids. However, its clinical use is hampered by the development of pathologic progesterone receptor modulator-associated endometrial changes (PAECs). The current study was designed to test the hypothesis that UPA-induced PAECs are associated with deranged expression of some metabolic genes. In addition, metformin can mitigate UPA-induced PAECs through modulating the expression of these genes. In the present study, twenty-eight female non-pregnant, nulligravid Wistar rats were treated with UPA (0.1 mg/kg/day, intragastric) and/or metformin (50 mg/kg/day, intragastric) for 8 weeks. Our results demonstrated that co-treatment with metformin significantly reduced UPA-induced PAECs. In addition, co-treatment with metformin and UPA was associated with significant increase in the Bax and significant reduction in Bcl-2, PCNA, Cyclin-D1and ER-α as compared to treatment with UPA alone. Furthermore, treatment with UPA alone was associated with deranged expression of 3-phosphoglycerate dehydrogenase (3-PHGDH), glucose-6-phosphate dehydrogenase (G6PD), transketolase (TKT), fatty acid synthase (FAS) and CD36. Most importantly, co-treatment with metformin markedly reduced UPA-induced altered expression of these metabolic genes in endometrial tissues. In conclusion, UPA-induced PAECs are associated with altered expression of genes involved in cell proliferation, apoptosis, estrogen receptor, glucose metabolism and lipid metabolism. Co-treatment with metformin abrogated UPA-induced PAECs most likely through the modulation of the expression of these genes.

Field carcinogenesis for risk stratification of colorectal cancer

Colorectal cancer (CRC) is characterized by genetic-environmental interplay leading to diffuse changes in the entire colonic mucosa (field carcinogenesis or field of injury) and to a pro-neoplastic genetic/epigenetic/physiological milieu. The clinical consequences are increased risk of synchronous and metachronous neoplasia. Factors such as genetics, race, ethnicity, age, and socioeconomic status are thought to influence neoplasia development. Here, we explore the potential improvement to CRC screening through exploiting field carcinogenesis, with particular focus on racial disparities and chemoprevention strategies. Also, we discuss future directions for field carcinogenesis/risk stratification using molecular and novel biophotonic techniques for personalized CRC screening.

Dynamic Changes of Mitochondrial DNA Copy Number in Gastrointestinal Tract Cancers: A Systematic Review and Meta-Analysis

We have performed a systematic review and meta-analysis for evaluation of mitochondrial DNA copy number (mtDNA-CN) alterations in peripheral blood leukocytes (PBL), and tumor tissues of gastrointestinal tract (GIT) cancers. Analysis of the PBL demonstrated a significant decrease [OR: 0.6 (0.5, 0.8)] and increase [OR: 1.4 (1.1, 1.9)] prior to and following GIT cancer development, respectively. This trend was more evident in CRC, and GC subgroups. Analysis of tissue yielded high levels of heterogeneity. However, the mean difference for the CRC subgroup was statistically significant [1.5 (1.0, 2.2)]. Our analysis suggests mtDNA-CN deserves further investigations as a GIT-cancer screening tool.

Metabolomics study reveals the potential evidence of metabolic reprogramming towards the Warburg effect in precancerous lesions

Background: Most tumors have an enhanced glycolysis flux, even when oxygen is available, called the aerobic glycolysis or the Warburg effect. Metabolic reprogramming promotes cancer progression, and is even related to the tumorigenesis. However, it is not clear whether the observed metabolic changes act as a driver or a bystander in cancer development.

Methods: In this study, the metabolic characteristics of oral precancerous cells and cervical precancerous lesions were analyzed by metabolomics, and the expression of glycolytic enzymes in cervical precancerous lesions was evaluated by RT-PCR and Western blot analysis.

Results: In total, 115 and 23 metabolites with reliable signals were identified in oral cells and cervical tissues, respectively. Based on the metabolome, oral precancerous cell DOK could be clearly separated from normal human oral epithelial cells (HOEC) and oral cancer cells. Four critical differential metabolites (pyruvate, glutamine, methionine and lysine) were identified between DOK and HOEC. Metabolic profiles could clearly distinguish cervical precancerous lesions from normal cervical epithelium and cervical cancer. Compared with normal cervical epithelium, the glucose consumption and lactate production increased in cervical precancerous lesions. The expression of glycolytic enzymes LDHA, HK II and PKM2 showed an increased tendency in cervical precancerous lesions compared with normal cervical epithelium.

Conclusions: Our findings suggest that cell metabolism may be reprogrammed at the early stage of tumorigenesis, implying the contribution of metabolic reprogramming to the development of tumor.

A systematic review of genes affecting mitochondrial processes in cancer

Malignant conversion of cancer cells requires efficient mitochondria reprogramming orchestrated by hundreds of genes. The transformation includes increased energy demand, biosynthesis of precursors, and reactive oxygen species needed to accelerate cell growth, proliferation, and survival. Reprogramming involves complex gene alterations that have not been methodically curated. Therefore, we systematically analyzed the literature of cancer-related genes in mitochondria. Through the analysis of >2500 PubMed abstracts and >1600 human genes, we identified 228 genes showing clear roles in cancer. Each gene was classified according to their homeostatic function, together with the pathological transitions that contribute to specific cancer hallmarks. The potential clinical relevance of these hallmarks and genes is discussed by representative examples and validated by detecting differences in gene expression levels across 16 different types of cancer. A compendium, including the gene functions and alterations underpinning cancer progression, can be explored at http://bioinformatica.mty.itesm.mx/MitoCancer.

Circulating Fibroblast Growth Factor-21 and Risk of Metachronous Colorectal Adenoma

PURPOSE

Prior work has shown that higher circulating concentrations of fibroblast growth factor-21 (FGF-21) are associated with an increased likelihood of developing colorectal cancer. We conducted a prospective study to assess the relationship between circulating FGF-21 and odds of developing early neoplastic lesions in the colorectum.

METHODS

A total of 94 study participants were included from the ursodeoxycholic acid (UDCA) trial, a phase III, randomized, double-blind, placebo-controlled clinical trial of the effect of 8-10 mg/kg of body weight UDCA vs. placebo. Logistic regression analyses were conducted to evaluate the association between baseline FGF-21 concentrations and odds of developing a metachronous adenoma.

RESULTS

Of the characteristics compared across tertiles of FGF-21 concentrations, including age, race, sex, BMI, and other variables, only a previous personal history of colorectal polyps prior to entry into the UDCA trial was statistically significantly related to FGF-21 levels, with a proportion of 26.7%, 56.7%, and 50.0% across the first, second, and third tertiles, respectively (p < 0.05). Higher circulating concentrations of FGF-21 were statistically significantly associated with greater odds of developing a metachronous colorectal adenoma. After adjusting for potential confounders and when compared with the lowest tertile of FGF-21, the adjusted ORs (95% CIs) for metachronous colorectal adenoma in the second and third tertiles were 4.72 (95% CI, 1.42-15.72) and 3.82 (95% CI, 1.15-12.68), respectively (p trend < 0.05).

CONCLUSION

Our results reveal for the first time that, in addition to a recently discovered association with colorectal cancer, circulating FGF-21 concentrations are significantly and directly associated with odds of developing metachronous colorectal adenoma.

The Regulatory Mechanisms of Dynamin-Related Protein 1 in Tumor Development and Therapy

Background: Various types of tumors are likely to acquire drug resistance over time. Hence, the development of novel therapies to overcome drug resistance is critical. Studies have demonstrated that drug resistance is closely associated with the dynamic regulation of mitochondria in tumor cells. The dynamin-related protein 1 (Drp1) is involved in the regulation of mitochondrial fission and plays an important role in maintaining mitochondrial morphology, function, and distribution. It is a key protein in mitochondrial quality control. Drp1 is a GTPase localized to the cytoplasm and is a potential target in cancer therapy. A variety of drugs targeting Drp1 have shown great promise in reducing the viability and proliferation of cancer cells. The dynamic regulation of Drp1-mediated mitochondria is closely associated with tumor development, and treatment. Aim: In this article, the authors reviewed the occurrence and progression of mitochondrial fission regulated by Drp1, and its influence on cell cycle, autophagy, apoptosis, migration, invasion, the molecular mechanism of tumor stemness, and metabolic reprogramming. Targeted inhibition of Drp1 and mitochondrial fission could reduce or prevent tumor occurrence and progression in a variety of cancers. Drp1 inhibitors could reduce tumor stemness and enhance tumor sensitivity to chemotherapeutic drugs. Conclusion: Research into identifying compounds that could specifically target Drp1 will be valuable for overcoming drug resistance in tumors.

MCU-induced mitochondrial calcium uptake promotes mitochondrial biogenesis and colorectal cancer growth

Mitochondrial calcium uniporter (MCU) has an important role in regulating mitochondrial calcium (Ca²⁺) homeostasis. Dysregulation of mitochondrial Ca²⁺ homeostasis has been implicated in various cancers. However, it remains unclear whether MCU regulates mitochondrial Ca²⁺ uptake to promote cell growth in colorectal cancer (CRC). Therefore, in the present study the expression of MCU in CRC tissues and its clinical significance were examined. Following which, the biological function of MCU-mediated mitochondrial Ca²⁺ uptake in CRC cell growth and the underlying mechanisms were systematically evaluated using in in vitro and in vivo assays, which included western blotting, cell viability and apoptosis assays, as well as xenograft nude mice models. Our results demonstrated that MCU was markedly upregulated in CRC tissues at both the mRNA and protein levels. Upregulated MCU was associated with poor prognosis in patients with CRC. Our data reported that upregulation of MCU enhanced the mitochondrial Ca²⁺ uptake to promote mitochondrial biogenesis, which in turn facilitated CRC cell growth in vitro and in vivo. In terms of the underlying mechanism, it was identified that MCU-mediated mitochondrial Ca²⁺ uptake inhibited the phosphorylation of transcription factor A, mitochondrial (TFAM), and thus enhanced its stability to promote mitochondrial biogenesis. Furthermore, our data indicated that increased mitochondrial Ca²⁺ uptake led to increased mitochondrial production of ROS via the upregulation of mitochondrial biogenesis, which subsequently activated NF-κB signaling to accelerate CRC growth. In conclusion, the results indicated that MCU-induced mitochondrial Ca²⁺ uptake promotes mitochondrial biogenesis by suppressing phosphorylation of TFAM, thus contributing to CRC cell growth. Our findings reveal a novel mechanism underlying mitochondrial Ca²⁺-mediated CRC cell growth and may provide a potential pharmacological target for CRC treatment.

Altered organization of collagen fibers in the uninvolved human colon mucosa 10 cm and 20 cm away from the malignant tumor

Remodelling of collagen fibers has been described during every phase of cancer genesis and progression. Changes in morphology and organization of collagen fibers contribute to the formation of microenvironment that favors cancer progression and development of metastasis. However, there are only few data about remodelling of collagen fibers in healthy looking mucosa distant from the cancer. Using SHG imaging, electron microscopy and specialized softwares (CT-FIRE, CurveAlign and FiberFit), we objectively visualized and quantified changes in morphology and organization of collagen fibers and investigated possible causes of collagen remodelling (change in syntheses, degradation and collagen cross-linking) in the colon mucosa 10 cm and 20 cm away from the cancer in comparison with healthy mucosa. We showed that in the lamina propria this far from the colon cancer, there were changes in collagen architecture (width, straightness, alignment of collagen fibers and collagen molecules inside fibers), increased representation of myofibroblasts and increase expression of collagen-remodelling enzymes (LOX and MMP2). Thus, the changes in organization of collagen fibers, which were already described in the cancer microenvironment, also exist in the mucosa far from the cancer, but smaller in magnitude.

Mitochondrial Respiration in KRAS and BRAF Mutated Colorectal Tumors and Polyps

This study aimed to characterize the ATP-synthesis by oxidative phosphorylation in colorectal cancer (CRC) and premalignant colon polyps in relation to molecular biomarkers KRAS and BRAF. This prospective study included 48 patients. Resected colorectal polyps and postoperative CRC tissue with adjacent normal tissue (control) were collected. Patients with polyps and CRC were divided into three molecular groups: KRAS mutated, BRAF mutated and KRAS/BRAF wild-type. Mitochondrial respiration in permeabilized tissue samples was observed using high resolution respirometry. ADP-activated respiration rate (V_max) and an apparent affinity of mitochondria to ADP, which is related to mitochondrial outer membrane (MOM) permeability, were determined. Clear differences were present between molecular groups. KRAS mutated CRC group had lower V_max values compared to wild-type; however, the V_max value was higher than in the control group, while MOM permeability did not change. This suggests that KRAS mutation status might be involved in acquiring oxidative phenotype. KRAS mutated polyps had higher V_max values and elevated MOM permeability as compared to the control. BRAF mutated CRC and polyps had reduced respiration and altered MOM permeability, indicating a glycolytic phenotype. To conclude, prognostic biomarkers KRAS and BRAF are likely related to the metabolic phenotype in CRC and polyps. Assessment of the tumor mitochondrial ATP synthesis could be a potential component of patient risk stratification.

New Insights in Candida albicans Innate Immunity at the Mucosa: Toxins, Epithelium, Metabolism, and Beyond

The mucosal surfaces of the human body are challenged by millions of microbes on a daily basis. Co-evolution with these microbes has led to the development of plastic mechanisms in both host and microorganisms that regulate the balance between preserving beneficial microbes and clearing pathogens. Candida albicans is a fungal pathobiont present in most healthy individuals that, under certain circumstances, can become pathogenic and cause everything from mild mucosal infections to life-threatening systemic diseases. As an essential part of the innate immunity in mucosae, epithelial cells elaborate complex immune responses that discriminate between commensal and pathogenic microbes, including C. albicans. Recently, several significant advances have been made identifying new pieces in the puzzle of host-microbe interactions. This review will summarize these advances in the context of our current knowledge of anti-Candida mucosal immunity, and their impact on epithelial immune responses to this fungal pathogen.

Serine racemase enhances growth of colorectal cancer by producing pyruvate from serine

Serine racemase (SRR) catalyses not only the racemization but also the dehydration of L-serine and D-serine, resulting in the formation of pyruvate and ammonia. Although SRR activity is important in the central nervous system, SRR has not been linked to cancer metabolism before. Here we show that SRR supports proliferation of colorectal-cancer cells. We find that SRR expression is upregulated in colorectal adenoma and adenocarcinoma lesions compared with non-neoplastic mucosa in human colorectal-cancer specimens. SRR-mediated dehydration of serine contributes to the pyruvate pool in colon-cancer cells, enhances proliferation, maintains mitochondrial mass and increases basal reactive oxygen species production, which has anti-apoptotic effects. Moreover, SRR promotes acetylation of histone H3 by maintaining intracellular acetyl-CoA levels. Inhibition of SRR suppresses growth of colorectal tumours in mice and augments the efficacy of 5-fluorouracil treatment. Our findings highlight a previously unknown mechanism through which a racemase supports cancer-cell growth and suggest that SRR might be a molecular target for colorectal-cancer therapy.

PKM2, function and expression and regulation

Pyruvate kinase (PK), as one of the key enzymes for glycolysis, can encode four different subtypes from two groups of genes, although the M2 subtype PKM2 is expressed mainly during embryonic development in normal humans, and is closely related to tissue repair and regeneration, with the deepening of research, the role of PKM2 in tumor tissue has received increasing attention. PKM2 can be aggregated into tetrameric and dimeric forms, PKM2 in the dimer state can enter the nuclear to regulate gene expression, the transformation between them can play an important role in tumor cell energy supply, epithelial-mesenchymal transition (EMT), invasion and metastasis and cell proliferation. We will use the switching effect of PKM2 in glucose metabolism as the entry point to expand and enrich the Warburg effect. In addition, PKM2 can also regulate each other with various proteins by phosphorylation, acetylation and other modifications, mediate the different intracellular localization of PKM2 and then exert specific biological functions. In this paper, we will illustrate each of these points.

Mitophagy in Cancer: A Tale of Adaptation

：In the past years, we have learnt that tumors co-evolve with their microenvironment, and that the active interaction between cancer cells and stromal cells plays a pivotal role in cancer initiation, progression and treatment response. Among the players involved, the pathways regulating mitochondrial functions have been shown to be crucial for both cancer and stromal cells. This is perhaps not surprising, considering that mitochondria in both cancerous and non-cancerous cells are decisive for vital metabolic and bioenergetic functions and to elicit cell death. The central part played by mitochondria also implies the existence of stringent mitochondrial quality control mechanisms, where a specialized autophagy pathway (mitophagy) ensures the selective removal of damaged or dysfunctional mitochondria. Although the molecular underpinnings of mitophagy regulation in mammalian cells remain incomplete, it is becoming clear that mitophagy pathways are intricately linked to the metabolic rewiring of cancer cells to support the high bioenergetic demand of the tumor. In this review, after a brief introduction of the main mitophagy regulators operating in mammalian cells, we discuss emerging cell autonomous roles of mitochondria quality control in cancer onset and progression. We also discuss the relevance of mitophagy in the cellular crosstalk with the tumor microenvironment and in anti-cancer therapy responses.

Molecular evidence of field cancerization initiated by diabetes in colon cancer patients

The potential involvement of type 2 diabetes mellitus (T2DM) as a risk factor for colon cancer (CC) has been previously reported. While several clinical studies show a higher incidence of CC and a lower survival rate in diabetics, others report no association. Our own experience indicates that diabetes does not seem to worsen the prognosis once the tumor is present. Despite this controversy, there are no wide‐spectrum molecular studies that delve into the impact of T2DM‐related mechanisms in colon carcinogenesis. Here, we present a transcriptomic and proteomic profiling of paired tumor and normal colon mucosa samples in a cohort of 42 CC patients, 23 of which have T2DM. We used gene set enrichment and network approaches to extract relevant pathways in diabetics, referenced them to current knowledge, and tested them using in vitro techniques. Through our transcriptomics approach, we identified an unexpected overlap of pathways overrepresented in diabetics compared to nondiabetics, in both tumor and normal mucosa, including diabetes‐related metabolic and signaling processes. Proteomic approaches highlighted several cancer‐related signaling routes in diabetics found only in normal mucosa, not in tumors. An integration of the transcriptome and proteome analyses suggested the deregulation of key pathways related to colon carcinogenesis which converged on tumor initiation axis TEAD/YAP‐TAZ as a potential initiator of the process. In vitro studies confirmed upregulation of this pathway in nontumor colon cells under high‐glucose conditions. In conclusion, T2DM associates with deregulation of cancer‐related processes in normal colon mucosa adjacent to tissue which has undergone a malignant transformation. These data support that in diabetic patients, the local microenvironment in normal colon mucosa may be a factor driving field cancerization promoting carcinogenesis. Our results set a new framework to study links between diabetes and colon cancer, including a new role of the TEAD/YAP‐TAZ complex as a potential driver.

Paris Saponin II inhibits colorectal carcinogenesis by regulating mitochondrial fission and NF-κB pathway

Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality worldwide. Accumulating evidence suggests that mitochondrial dynamics are closely implicated in carcinogenesis including CRC. Paris Saponin II (PSII), a major steroidal saponin extracted from Rhizoma Paris polyphylla, has emerged as a potential anticancer agent. However, the effects of PSII on CRC and its underlying mechanisms remain unknown. In the present study, we found PSII induced apoptosis and inhibited colony formation in HT 29 and HCT 116 cells, and cell cycle arrest in G1 phase. PSII inhibited the phosphorylation of ERK1/2 and mitochondrial translocation of dynamin-related protein 1 (Drp1) by dephosphorylating Drp1 at Ser616, leading to the suppression of mitochondrial fission. PSII also suppressed NF-κB activation as a result of the inhibition of IKKβ and p65 translocation. Drp1 knockdown remarkably downregulated the nuclear expression of p65 and its target genes cyclin D1 and c-Myc in HCT 116 cell, confirming the link between mitochondrial fission and NF-κB pathway. Silencing of Drp 1 enhanced the inhibitory effects of PSII on p65 phosphorylation and the expressions of cyclin D1 and c-Myc, revealing that the inhibitory effects of PSII on cyclin D1 and c-Myc were relevant in the suppression of Drp1 and NF-κB activation. An in vivo study demonstrated PSII remarkably decreased the xenograft tumor size and suppressed the phosphorylation of ERK1/2 and Drp1 at Ser616. Taken together, our results suggested that PSII could inhibit colorectal carcinogenesis, at least in part, by regulating mitochondrial fission and NF-κB pathway.

Colorectal Cancer and Metabolism

Purpose of Review

Metabolic reprogramming is essential for the rapid proliferation of cancer cells and is thus recognized as a hallmark of cancer. In this review, we will discuss the etiologies and effects of metabolic reprogramming in colorectal cancer.

Recent Findings

Changes in cellular metabolism may precede the acquisition of driver mutations ultimately leading to colonocyte transformation. Oncogenic mutations and loss of tumor suppressor genes further reprogram CRC cells to upregulate glycolysis, glutaminolysis, one-carbon metabolism, and fatty acid synthesis. These metabolic changes are not uniform throughout tumors, as subpopulations of tumor cells may rely on different pathways to adapt to nutrient availability in the local tumor microenvironment. Finally, metabolic cross-communication between stromal cells, immune cells, and the gut microbiota enable CRC growth, invasion, and metastasis.

Summary

Altered cellular metabolism occurs in CRC at multiple levels, including in the cells that make up the bulk of CRC tumors, cancer stem cells, the tumor microenvironment, and host-microbiome interactions. This knowledge may inform the development of improved screening and therapeutics for CRC.

Fibroblast growth factor 21 as a circulating biomarker at various stages of colorectal carcinogenesis

Background

Despite evidence that inflammation and metabolism play a crucial role in colorectal carcinogenesis, there have been few studies on the association of inflammatory and metabolic protein biomarkers in various stages of colorectal carcinogenesis.

Methods

Ninety-two inflammatory and metabolic biomarkers were measured in plasma samples of participants of screening colonoscopy. Markers identified to be significantly associated with the presence of advanced colorectal neoplasia (ACN) in a discovery set (n = 204) were validated in an independent replication set (n = 422). Adjusted associations with the presence of non-advanced adenomas (NAA), advanced precancerous lesions (APL) and colorectal cancer (CRC) were quantified by multiple logistic regression.

Results

Out of the 92 inflammatory proteins, 72 markers were evaluable and 8 showed statistically significant associations with the odds of ACN after full adjustment for potential risk factors for CRC in the discovery set. One of these, fibroblast growth factor 21 (FGF-21), could be validated in the replication set. The multivariable-adjusted odds ratio (OR) reached 2.65 (95% CI, 1.50–4.81) for individuals with FGF-21 levels within the highest tertile, compared to those within the lowest tertile (P_trend across tertiles = 0.001). Separate models revealed fully adjusted ORs for NAA, APL and CRC of 2.99 (95% CI, 1.45–6.58, P_trend = 0.005), 2.24 (95% CI, 1.18–4.44, P_trend = 0.021) and 3.92 (95% CI, 1.51–12.18, P_trend = 0.003), respectively.

Conclusions

Circulating FGF-21 level is associated with increased risk of early and late stages of colorectal carcinogenesis, supporting a role of inflammation and metabolism at all stages of colorectal carcinogenesis, and suggesting potential use of this biomarker for risk stratification in CRC screening.

Mitochondrial Uncoupling Proteins: Subtle Regulators of Cellular Redox Signaling

SIGNIFICANCE

Mitochondria are the energetic, metabolic, redox, and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics, and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the mentioned aspects, being involved in numerous physiological events including redox signaling. Recent Advances: UCP2 structure, including purine nucleotide and fatty acid (FA) binding sites, strongly support the FA cycling mechanism: UCP2 expels FA anions, whereas uncoupling is achieved by the membrane backflux of protonated FA. Nascent FAs, cleaved by phospholipases, are preferential. The resulting Δp dissipation decreases superoxide formation dependent on Δp. UCP-mediated antioxidant protection and its impairment are expected to play a major role in cell physiology and pathology. Moreover, UCP2-mediated aspartate, oxaloacetate, and malate antiport with phosphate is expected to alter metabolism of cancer cells.

CRITICAL ISSUES

A wide range of UCP antioxidant effects and participations in redox signaling have been reported; however, mechanisms of UCP activation are still debated. Switching off/on the UCP2 protonophoretic function might serve as redox signaling either by employing/releasing the extra capacity of cell antioxidant systems or by directly increasing/decreasing mitochondrial superoxide sources. Rapid UCP2 degradation, FA levels, elevation of purine nucleotides, decreased Mg²⁺, or increased pyruvate accumulation may initiate UCP-mediated redox signaling.

FUTURE DIRECTIONS

Issues such as UCP2 participation in glucose sensing, neuronal (synaptic) function, and immune cell activation should be elucidated. Antioxid. Redox Signal. 29, 667-714.

Dynamin-Related Protein 1 at the Crossroads of Cancer

Mitochondrial dynamics are known to have an important role in so-called age-related diseases, including cancer. Mitochondria is an organelle involved in many key cellular functions and responds to physiologic or stress stimuli by adapting its structure and function. Perhaps the most important structural changes involve mitochondrial dynamics (fission and fusion), which occur in normal cells as well as in cells under dysregulation, such as cancer cells. Dynamin-related protein 1 (DRP1), a member of the dynamin family of guanosine triphosphatases (GTPases), is the key component of mitochondrial fission machinery. Dynamin-related protein 1 is associated with different cell processes such as apoptosis, mitochondrial biogenesis, mitophagy, metabolism, and cell proliferation, differentiation, and transformation. The role of DRP1 in tumorigenesis may seem to be paradoxical, since mitochondrial fission is a key mediator of two very different processes, cellular apoptosis and cell mitosis. Dynamin-related protein 1 has been associated with the development of distinct human cancers, including changes in mitochondrial energetics and cellular metabolism, cell proliferation, and stem cell maintenance, invasion, and promotion of metastases. However, the underlying mechanism for this association is still being explored. Herein, we review the published knowledge on the role of DRP1 in cancer, exploring its interaction with different biological processes in the tumorigenesis context.

Pyruvate Kinase M2 Modulates the Glycolysis of Chondrocyte and Extracellular Matrix in Osteoarthritis

Pyruvate kinase M2 (PKM2) has been wildly verified to modulate glycolysis in tumor cells. However, the role of PKM2 on the glycolysis of osteoarthritis (OA) chondrocytes is still unclear. In present study, we investigate the function of PKM2 on OA chondrocyte glycolysis and the collagen matrix generation in vitro. Results showed that PKM2 was upregulated in OA chondrocytes compared with healthy control chondrocytes. In OA chondrocytes, ATP expression was lower compared with healthy control chondrocytes. Loss-of-function experiment showed that PKM2 knockdown mediated by lentivirus transfection could significantly suppress the glucose consumption and lactate secretion levels and decrease glucose transporter-1 (Glut-1), lactate dehydrogenase A (LDHA), and hypoxia inducible factor 1-alpha (HIF-1α), indicating the inhibition of PKM2 knockdown on glycolysis. Moreover, Cell Counting Kit-8 (CCK-8), flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay showed that PKM2 knockdown inhibited OA chondrocyte proliferation and promoted the apoptosis. Western blot and immunocytochemical staining showed that PKM2 knockdown downregulated the expression levels of COL2A1 and SOX-9. In summary, our results conclude that PKM2 modulates the glycolysis and extracellular matrix generation, providing the vital role of PKM2 on OA pathogenesis and a novel therapeutic target for OA.

Label-free optical imaging technologies for rapid translation and use during intraoperative surgical and tumor margin assessment

The biannual International Conference on Biophotonics was recently held on April 30 to May 1, 2017, in Fremantle, Western Australia. This continuing conference series brought together key opinion leaders in biophotonics to present their latest results and, importantly, to participate in discussions on the future of the field and what opportunities exist when we collectively work together for using biophotonics for biological discovery and medical applications. One session in this conference, entitled "Tumor Margin Identification: Critiquing Technologies," challenged invited speakers and attendees to review and critique representative label-free optical imaging technologies and their application for intraoperative assessment and guidance in surgical oncology. We are pleased to share a summary in this outlook paper, with the intent to motivate more research inquiry and investigations, to challenge these and other optical imaging modalities to evaluate and improve performance, to spur translation and adoption, and ultimately, to improve the care and outcomes of patients.