Interplay between VHL/HIF1α and Wnt/β-catenin pathways during colorectal tumorigenesis

Astragali Radix-Curcumae Rhizoma herb pair reduces the stemness of colorectal cancer cells through HIF-2α/β-catenin pathway

BACKGROUND

Colorectal cancer (CRC) is one of the most common causes of cancer-related mortality and significantly impairs quality of life. Astragali Radix-Curcumae Rhizoma (AC) is widely employed in the treatment of CRC in Chinese medicine, but the precise mechanisms remain unclear.

PURPOSE

This study aimed to elucidate the mechanisms by which AC inhibits CRC progression.

METHODS

The active components of AC were identified using UPLC-MS/MS analysis. An orthotopic transplantation colorectal tumor model was established in BALB/c mice using the CT26-Lucifer cell line to evaluate the effects of AC. Tumor volumes were monitored using IVIS imaging technology. Histological examination of tumor morphology was performed with hematoxylin and eosin (H&E) staining. Transcriptomic sequencing of mouse tumor samples was conducted to identify critical pathways and molecular targets. The impact of AC on cell viability and migration was assessed using CCK-8 and wound healing assays, respectively. To investigate the effects of AC on CRC cells, an in vitro hypoxic model was established using cobalt chloride (CoCl2), a hypoxia inducer. HIF-2α overexpression was achieved by constructing stable lentiviral vectors. Key targets identified from RNA-seq, such as c-Myc, Ki-67, β-catenin, cleaved caspase 3, CD133, and CD44, were evaluated using western blotting, qRT-PCR, and immunofluorescence assays. Epithelial-Mesenchymal Transition (EMT) and spheroid cloning assays were employed to evaluate phenotypic changes in cancer stem cells.

RESULTS

Twelve components of AC were identified. AC effectively inhibited CRC progression in vivo. Transcriptomic analysis highlighted hypoxic signaling as a significantly enriched pathway, implicating its role in suppressing CRC progression by AC. In the hypoxic model, AC inhibited the proliferation and migration of CRC cells in vitro. Furthermore, AC reduced cancer stemness by downregulating stemness markers, inhibiting EMT, and decreasing tumor sphere formation. The downregulation of hypoxic responses and the shift in stemness by AC involved attenuation of HIF-2α and WNT/β-catenin signaling.

CONCLUSION

This study provides the first evidence that AC reduces the stemness of CRC and the inhibition of the transition of CRC to stem-like cells by AC is closely related to the downregulation of the HIF-2α/β-catenin pathway, especially under hypoxic conditions.

Canonical Wnt signaling promotes HSC glycolysis and liver fibrosis through an LDH-A/HIF-1α transcriptional complex

BACKGROUND AND AIMS

Aerobic glycolysis reprogramming occurs during HSC activation, but how it is initiated and sustained remains unknown. We investigated the mechanisms by which canonical Wnt signaling regulated HSC glycolysis and the therapeutic implication for liver fibrosis.

APPROACH AND RESULTS

Glycolysis was examined in HSC-LX2 cells upon manipulation of Wnt/β-catenin signaling. Nuclear translocation of lactate dehydrogenase A (LDH-A) and its interaction with hypoxia-inducible factor-1α (HIF-1α) were investigated using molecular simulation and site-directed mutation assays. The pharmacological relevance of molecular discoveries was intensified in primary cultures, rodent models, and human samples. HSC glycolysis was enhanced by Wnt3a but reduced by β-catenin inhibitor or small interfering RNA (siRNA). Wnt3a-induced rapid transactivation and high expression of LDH-A dependent on TCF4. Wnt/β-catenin signaling also stimulated LDH-A nuclear translocation through importin β2 interplay with a noncanonical nuclear location signal of LDH-A. Mechanically, LDH-A bound to HIF-1α and enhanced its stability by obstructing hydroxylation-mediated proteasome degradation, leading to increased transactivation of glycolytic genes. The Gly28 residue of LDH-A was identified to be responsible for the formation of the LDH-A/HIF-1α transcription complex and stabilization of HIF-1α. Furthermore, LDH-A-mediated glycolysis was required for HSC activation in the presence of Wnt3a. Results in vivo showed that HSC activation and liver fibrosis were alleviated by HSC-specific knockdown of LDH-A in mice. β-catenin inhibitor XAV-939 mitigated HSC activation and liver fibrosis, which were abrogated by HSC-specific LDH-A overexpression in mice with fibrosis.

CONCLUSIONS

Inhibition of HSC glycolysis by targeting Wnt/β-catenin signaling and LDH-A had therapeutic promise for liver fibrosis.

Emerging trends in gastrointestinal cancers: Targeting developmental pathways in carcinogenesis and tumor progression

Gastrointestinal carcinomas are a group of cancers associated with the digestive system and its accessory organs. The most prevalent cancers related to the gastrointestinal tract are colorectal, gall bladder, gastric, hepatocellular, and esophageal cancers, respectively. Molecular aberrations in different signaling pathways, such as signal transduction systems or developmental pathways are the chief triggering mechanisms in different cancers Though a massive advancement in diagnostic and therapeutic interventions results in improved survival of patients with gastrointestinal cancer; the lower malignancy stages of these carcinomas are comparatively asymptomatic. Various gastrointestinal-related cancers are detected at advanced stages, leading to deplorable prognoses and increased rates of recurrence. Recent molecular studies have elucidated the imperative roles of several signaling pathways, namely Wnt, Hedgehog, and Notch signaling pathways, play in the progression, therapeutic responsiveness, and metastasis of gastrointestinal-related cancers. This book chapter gives an interesting update on recent findings on the involvement of developmental signaling pathways their mechanistic insight in gastrointestinalcancer. Subsequently, evidences supporting the exploration of gastrointestinal cancer related molecular mechanisms have also been discussed for developing novel therapeutic strategies against these debilitating carcinomas.

Pioneering therapies for post-infarction angiogenesis: Insight into molecular mechanisms and preclinical studies

Acute myocardial infarction (MI), despite significant progress in its treatment, remains a leading cause of chronic heart failure and cardiovascular events such as cardiac arrest. Promoting angiogenesis in the myocardial tissue after MI to restore blood flow in the ischemic and hypoxic tissue is considered an effective treatment strategy. The repair of the myocardial tissue post-MI involves a robust angiogenic response, with mechanisms involved including endothelial cell proliferation and migration, capillary growth, changes in the extracellular matrix, and stabilization of pericytes for neovascularization. In this review, we provide a detailed overview of six key pathways in angiogenesis post-MI: the PI3K/Akt/mTOR signaling pathway, the Notch signaling pathway, the Wnt/β-catenin signaling pathway, the Hippo signaling pathway, the Sonic Hedgehog signaling pathway, and the JAK/STAT signaling pathway. We also discuss novel therapeutic approaches targeting these pathways, including drug therapy, gene therapy, protein therapy, cell therapy, and extracellular vesicle therapy. A comprehensive understanding of these key pathways and their targeted therapies will aid in our understanding of the pathological and physiological mechanisms of angiogenesis after MI and the development and application of new treatment strategies.

Colorectal polyps increase the glycolytic activity

In colorectal cancer (CRC) energy metabolism research, the precancerous stage of polyp has remained rather unexplored. By now, it has been shown that CRC has not fully obtained the glycolytic phenotype proposed by O. Warburg and rather depends on mitochondrial respiration. However, the pattern of metabolic adaptations during tumorigenesis is still unknown. Understanding the interplay between genetic and metabolic changes that initiate tumor development could provide biomarkers for diagnosing cancer early and targets for new cancer therapeutics. We used human CRC and polyp tissue material and performed high-resolution respirometry and qRT-PCR to detect changes on molecular and functional level with the goal of generally describing metabolic reprogramming during CRC development. Colon polyps were found to have a more glycolytic bioenergetic phenotype than tumors and normal tissues. This was supported by a greater GLUT1, HK, LDHA, and MCT expression. Despite the increased glycolytic activity, cells in polyps were still able to maintain a highly functional OXPHOS system. The mechanisms of OXPHOS regulation and the preferred substrates are currently unclear and would require further investigation. During polyp formation, intracellular energy transfer pathways become rearranged mainly by increasing the expression of mitochondrial adenylate kinase (AK) and creatine kinase (CK) isoforms. Decreased glycolysis and maintenance of OXPHOS activity, together with the downregulation of the CK system and the most common AK isoforms (AK1 and AK2), seem to play a relevant role in CRC development.

Wnt3a is a promising target in colorectal cancer

Most colorectal cancers (CRC) are associated with activated Wnt signaling, making it the fourth most prevalent type of cancer globally. To function properly, the Wnt signaling pathway requires secreted glycoproteins known as Wnt ligands (Wnts). Humans have 19 Wnts, which suggest a complicated signaling and biological process, and we still know little about their functions in developing CRC. This review aims to describe the canonical Wnt signaling in CRC, particularly the Wnt3a expression pattern, and their association with the angiogenesis and progression of CRC. This review also sheds light on the inhibition of Wnt3a signaling in CRC. Despite some obstacles, a thorough understanding of Wnts is essential for effectively managing CRC.

Visible light-initiated radical 1,3-difunctionalization of β,γ-unsaturated ketones

Radical-mediated 1,2-difunctionalization of olefins is a well-established synthetic technique widely used in the rapid construction of structurally diverse molecular entities. However, radical-mediated 1,3-difunctionalization reactions are rare, and the substrates are generally limited to strained skeletons. Here, we report a practical approach for 1,3-difunctionalization of available β,γ-unsaturated ketones via a radical cascade process including visible light-irradiated radical addition, thermodynamic stability-driven 1,2-carbonyl migration from unactivated all-carbon quaternary center, and terminal C-radical varied transformations. Various highly functionalized alkyl skeletons with different valuable functional groups at positions 1 and 3 and the carbonyl group at position 2 have been synthesized through a radical chain pathway or Cu-catalyzed Ritter-type reaction. Moreover, this protocol provides a real case of diversity-oriented radical rearrangement for drug discovery. We identified a previously unknown chemotype of dual inhibitors for hypoxia-inducible factor (HIF) and WNT signaling pathways from products. These small-molecule inhibitors could suppress HIF and WNT signaling-dependent HCT116 cell growth in 2D and 3D culture systems.

Mechanisms shared between cancer, heart failure, and targeted anti-cancer therapies

Heart failure (HF) and cancer are the leading causes of death worldwide and accumulating evidence demonstrates that HF and cancer affect one another in a bidirectional way. Patients with HF are at increased risk for developing cancer, and HF is associated with accelerated tumour growth. The presence of malignancy may induce systemic metabolic, inflammatory, and microbial alterations resulting in impaired cardiac function. In addition to pathophysiologic mechanisms that are shared between cancer and HF, overlaps also exist between pathways required for normal cardiac physiology and for tumour growth. Therefore, these overlaps may also explain the increased risk for cardiotoxicity and HF as a result of targeted anti-cancer therapies. This review provides an overview of mechanisms involved in the bidirectional connection between HF and cancer, specifically focusing upon current 'hot-topics' in these shared mechanisms. It subsequently describes targeted anti-cancer therapies with cardiotoxic potential as a result of overlap between their anti-cancer targets and pathways required for normal cardiac function.

Metabolic resistance to the inhibition of mitochondrial transcription revealed by CRISPR-Cas9 screen

Cancer cells depend on mitochondria to sustain their increased metabolic need and mitochondria therefore constitute possible targets for cancer treatment. We recently developed small-molecule inhibitors of mitochondrial transcription (IMTs) that selectively impair mitochondrial gene expression. IMTs have potent antitumor properties in vitro and in vivo, without affecting normal tissues. Because therapy-induced resistance is a major constraint to successful cancer therapy, we investigated mechanisms conferring resistance to IMTs. We employed a CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats)-(CRISP-associated protein 9) whole-genome screen to determine pathways conferring resistance to acute IMT1 treatment. Loss of genes belonging to von Hippel-Lindau (VHL) and mammalian target of rapamycin complex 1 (mTORC1) pathways caused resistance to acute IMT1 treatment and the relevance of these pathways was confirmed by chemical modulation. We also generated cells resistant to chronic IMT treatment to understand responses to persistent mitochondrial gene expression impairment. We report that IMT1-acquired resistance occurs through a compensatory increase of mitochondrial DNA (mtDNA) expression and cellular metabolites. We found that mitochondrial transcription factor A (TFAM) downregulation and inhibition of mitochondrial translation impaired survival of resistant cells. The identified susceptibility and resistance mechanisms to IMTs may be relevant for different types of mitochondria-targeted therapies.

Hypoxia effects on cancer stem cell phenotype in colorectal cancer: a mini-review

Colorectal cancer (CRC) is ranked third most incident and second most deadly around the world, and even though treatments significantly developed over the years, overall survival remains low. This scenario has the contribution of cancer stem cells (CSC), a subpopulation of the heterogeneous tumor bulk, considered to be responsible for the tumor maintenance, conventional therapies resistance, metastasis, and recurrence. In this regard, hypoxia appears as an important component of tumor microenvironment and CSC niche, being associated with a worse prognosis. Therefore, it is vital the study of hypoxia influence on CSC phenotype in CRC. The aim of this mini-review article is to present a brief overview on this field. Recent articles discoursed about CSC molecular regulation, signalling pathways, methods for the study of the topic, as well as molecules and drugs capacity of inhibiting the interplay of hypoxia-CSC. Finally, the studies demonstrated important results, extensively accessing the topics of cellular and molecular regulation and therapeutic intervention, being morphology an area to be more explored.

Cartilage Endplate Stem Cells Transdifferentiate Into Nucleus Pulposus Cells via Autocrine Exosomes

Stem cells derived from cartilage endplate (CEP) cells (CESCs) repair intervertebral disc (IVD) injury; however, the mechanism remains unclear. Here, we evaluated whether CESCs could transdifferentiate into nucleus pulposus cells (NPCs) via autocrine exosomes and subsequently inhibit IVD degeneration. Exosomes derived from CESCs (CESC-Exos) were extracted and identified by ultra-high-speed centrifugation and transmission electron microscopy. The effects of exosomes on the invasion, migration, and differentiation of CESCs were assessed. The exosome-activating hypoxia-inducible factor (HIF)-1α/Wnt pathway was investigated using lenti-HIF-1α and Wnt agonists/inhibitors in cells and gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis in normal and degenerated human CEP tissue. The effects of GATA binding protein 4 (GATA4) on transforming growth factor (TGF)-β expression and on the invasion, migration, and transdifferentiation of CESCs were investigated using lenti-GATA4, TGF-β agonists, and inhibitors. Additionally, IVD repair was investigated by injecting CESCs overexpressing GATA4 into rats. The results indicated that CESC-Exos promoted the invasion, migration, and differentiation of CESCs by autocrine exosomes via the HIF-1α/Wnt pathway. Additionally, increased HIF-1α enhanced the activation of Wnt signaling and activated GATA4 expression. GATA4 effectively promoted TGF-β secretion and enhanced the invasion, migration, and transdifferentiation of CESCs into NPCs, resulting in promotion of rat IVD repair. CESCs were also converted into NPCs as endplate degeneration progressed in human samples. Overall, we found that CESC-Exos activated HIF-1α/Wnt signaling via autocrine mechanisms to increase the expression of GATA4 and TGF-β1, thereby promoting the migration of CESCs into the IVD and the transformation of CESCs into NPCs and inhibiting IVDD.

SUMOylation Connects Cell Stress Responses and Inflammatory Control: Lessons From the Gut as a Model Organ

Conjugation with the small ubiquitin-like modifier (SUMO) constitutes a key post-translational modification regulating the stability, activity, and subcellular localization of its target proteins. However, the vast numbers of identified SUMO substrates obscure a clear view on the function of SUMOylation in health and disease. This article presents a comprehensive review on the physiological relevance of SUMOylation by discussing how global SUMOylation levels—rather than specific protein SUMOylation—shapes the immune response. In particular, we highlight the growing body of work on SUMOylation in intestinal pathologies, because of the unique metabolic, infectious, and inflammatory challenges of this organ. Recent studies show that global SUMOylation can help restrain detrimental inflammation while maintaining immune defenses and tissue integrity. These results warrant further efforts to develop new therapeutic tools and strategies to control SUMOylation in infectious and inflammatory disorders.

Hypoxia Inducible Factor-1alpha (HIF-1A) plays different roles in Gallbladder Cancer and Normal Gallbladder Tissues

Purpose: Hypoxia-inducible factor-1alpha (HIF-1A) is a transcription factor that plays an “angiogenic switch” role especially under hypoxia microenvironment in solid tumor. However, the functions and clinical significance of HIF-1A in gallbladder cancer (GBC) are still controversial, and it has not been studied in normal gallbladder tissues. In this study, we sought to clarify the role of sub-cellular localization of HIF-1A expression in GBC and normal gallbladder tissues.

Methods: The expressions of HIF-1A and CD34 in 127 GBC and 47 normal gallbladder tissues were evaluated by immunohistochemistry. Cox's proportional hazards model analysis and Kaplan-Meier method analysis were used to assess the correlations between these factors and clinicopathological features and prognosis.

Results: HIF-1A was expressed in both cytoplasm and nucleus of GBC and normal control tissues, and was significantly correlated with microvessel density (MVD). GBC tissues with positive nuclear HIF-1A expression had higher MVD compared to that with positive cytoplasmic HIF-1A expression; however, in normal gallbladder tissues, samples with positive cytoplasmic HIF-1A had higher MVD compared to that with positive nuclear HIF-1A expression. Moreover, GBC with nuclear HIF-1A expression tended to be more poorly differentiated and had larger tumor size compared to that with cytoplasm HIF-1A expression. Furthermore, GBC patients with nuclear HIF-1A positive were significantly correlated with worse overall survival (OS) compared with cytoplasmic HIF-1A positive. Multivariate Cox regression analysis identified lymph node metastasis and nuclear HIF-1A expression to be independent prognostic parameter in GBC.

Conclusions: Our findings provide evidence for the first time that HIF-1A is expressed in normal gallbladder tissues. Nuclear HIF-1A and cytoplasm HIF-1A plays different roles in GBC and normal gallbladder tissues.

P4HA1 regulates human colorectal cancer cells through HIF1α-mediated Wnt signaling

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy that is associated with high levels of mortality. CRCs are often associated with an aberrant wingless-type mouse mammary tumor virus integration site family (Wnt) signaling pathway known to be responsible for tumorigenesis and cancer progression. Other factors that contribute to CRC pathology include hypoxia, extracellular matrix and cellular microenvironment. In the present study, modulation of Wnt, a common molecular progenitor for CRC-associated pathology was evaluated. CRC tissues and specific cell lines were found to exhibit increased expression levels of prolyl 4-hydroxylase subunit α1 (P4HA1). P4HA1 expression was found to stabilize hypoxia inducible factor-1α (HIF1α). The silencing of P4HA1 resulted in decreased cell proliferation, cell cycle arrest in the G₁ phase, decreased tumorsphere formation, decreased tumorsphere volume, increased susceptibility to 5-fluorouracil and increased caspase-3 activity. However, P4HA1 silencing resulted in the activation and thus proteasomal degradation of β-catenin, indicative of the abrogation of Wnt signaling pathway. Wnt is a critical signaling pathway and is activated in most CRCs. HIF1α is a poor prognostic marker in CRC. The present study provided preliminary evidence that HIF1α and the Wnt signaling pathway in CRC are modulated through P4HA1. P4HA1 may serve not just as a biomarker for CRC prognosis but may also be targeted for potential therapeutic intervention.

Activation of Wnt/β-catenin signalling and HIF1α stabilisation alters pluripotency and differentiation/proliferation properties of human-induced pluripotent stem cells

BACKGROUND INFORMATION

Wnt/β-catenin signalling, in the microenvironment of pluripotent stem cells (PSCs), plays a critical role in their differentiation and proliferation. Contradictory reports on the role of Wnt/β-catenin signalling in PSCs self-renewal and differentiation, however, render these mechanisms largely unclear.

RESULTS

Wnt/β-catenin signalling pathway in human-induced pluripotent stem cells (hiPSCs) was activated by inhibiting glycogen synthase kinase 3 (GSK3), driving the cells into a mesodermal/mesenchymal state, exhibiting proliferative, invasive and anchorage-independent growth properties, where over 70% of cell population became CD 44 (+)/CD133 (+). Wnt/β-catenin signalling activation also altered the metabolic state of hiPSCs from aerobic glycolysis to oxidative metabolism and changed their drug and oxidative stress sensitivities. These effects of GSK3 inhibition were suppressed in HIF1α-stabilised cells.

CONCLUSIONS

Persistent activation of Wnt/β-catenin signalling endows hiPSCs with proliferative/invasive 'teratoma-like' states, shifting their metabolic dependence and allowing HIF1α-stabilisation to inhibit their proliferative/invasive properties.

SIGNIFICANCE

The hiPSC potential to differentiate into 'teratoma-like' cells suggest that stem cells may exist in two states with differential metabolic and drug dependency.

Plantamajoside inhibits hypoxia-induced migration and invasion of human cervical cancer cells through the NF-κB and PI3K/akt pathways

Plantamajoside (PMS) is a major compound of Plantago asiatica and possesses anti-tumor property in several types of cancers. However, the effect of PMS on cervical cancer has not been investigated. This study aimed to investigate the effect of PMS on the migration and invasion of cervical cancer cell lines under hypoxic condition. Our results demonstrated that PMS significantly inhibited hypoxia-caused increases in cell migration and invasion of cervical cancer cells. The hypoxia-induced epithelial-mesenchymal transition (EMT) process was prevented by PMS with increased E-cadherin expression, and decreased expression levels of N-cadherin and vimentin in cervical cancer cells. Besides, the expression levels of transcription factors slug and snail were suppressed by PMS in hypoxia-induced cervical cancer cells. The increased mRNA and protein levels of hypoxia-inducible factor 1alpha (HIF-1α) in hypoxia-induced cervical cancer cells were prevented by PMS. Furthermore, PMS blocked the hypoxia-induced activation of NF-κB and PI3K/Akt pathway in cervical cancer cells. Taken together, these findings suggest that PMS exerted an anti-tumor activity in cervical cancer through preventing the hypoxia-induced EMT. Thus, PMS might serve as a therapeutic agent for the treatment of cervical cancer.

Cartilage Homeostasis Affects Femoral Head Necrosis Induced by Methylprednisolone in Broilers

(1) Background: Since the large-scale poultry industry has been established, femoral head necrosis (FHN) has always been a major leg disease in fast-growing broilers worldwide. Previous research suggested that cartilage homeostasis could be taken into consideration in the cause of FHN, but the evidence is insufficient. (2) Methods: One-day-old broiler chickens were randomly divided into three groups, 16 broilers per group. The birds in group L were injected intramuscularly with methylprednisolone (MP) twice a week for four weeks (12.5 mg·kg⁻¹). The birds in group H were injected intramuscularly with MP (20 mg·kg⁻¹·d⁻¹) for 7 d (impulse treatment). The birds in group C were treated with sterile saline as a control group. Broilers were sacrificed at 42 and 56 d. Blood samples were collected from the jugular vein for ELISA and biochemical analysis. Bone samples, including femur, tibia, and humerus, were collected for histopathological analysis, bone parameters detection, and real-time quantitative PCR detection. (3) Results: The FHN broilers in group L and H both showed lower body weight (BW) and reduced bone parameters. In addition, the MP treatment resulted in reduced extracellular matrix (ECM) anabolism and enhanced ECM catabolism. Meanwhile, the autophagy and apoptosis of chondrocytes were enhanced, which led to the destruction of cartilage homeostasis. Moreover, the impulse MP injection increased the portion of birds with severer FHN, whereas the MP injection over a long period caused a more evident change in serum cytokine concentrations and bone metabolism indicators. (4) Conclusions: The imbalance of cartilage homeostasis may play a critical role in the development of FHN in broilers. FHN broilers induced by MP showed a more pronounced production of catabolic factors and suppressed the anabolic factors, which might activate the genes of the WNT signal pathway and hypoxia-inducible factors (HIFs), and then upregulate the transcription expression of ECM to restore homeostasis.

Dehydroeffusol inhibits hypoxia-induced epithelial-mesenchymal transition in non-small cell lung cancer cells through the inactivation of Wnt/β-catenin pathway

Dehydroeffusol (DHE) is a phenanthrene compound that possesses anti-tumor activity. However, the effect of DHE on non-small cell lung cancer (NSCLC) has not been investigated previously. Therefore, the objective of our study was to explore the role of DHE in NSCLC and the underlying mechanism. Our results showed that DHE significantly inhibited the cell viability of A549 cells in a dose- and time-dependent manner under normoxic condition. Moreover, A549 cells were more sensitive to DHE under hypoxic condition compared with the A549 cells cultured in normoxic condition. Hypoxia-induced increased migration and invasion abilities were mitigated by DHE in A549 cells. Treatment of DHE caused increased E-cadherin expression and decreased N-cadherin expression in hypoxia-induced A549 cells. DHE also suppressed hypoxia-induced increase in both protein and mRNA levels of hypoxia inducible factor-1α (HIF-1α) expression in A549 cells. Furthermore, DHE inhibited hypoxia-induced activation of Wnt/β-catenin pathway in A549 cells. The inhibitory effect of DHE on hypoxia-induced EMT was reversed by LiCl, which is an activator of Wnt/β-catenin signaling pathway. In conclusion, these findings demonstrated that DHE prevented hypoxia-induced EMT in NSCLC cells by inhibiting the activation of Wnt/β-catenin pathway, suggesting that DHE might serve as a therapeutic target for the NSCLC metastasis.

Emerging Roles of Wnt Ligands in Human Colorectal Cancer

Colorectal cancer (CRC) is the fourth leading cause of cancer death worldwide, and constitutive activation of the Wnt signaling pathway is universal in most CRC cases. Wnt ligands (Wnts) are secreted glycoproteins and fundamentally essential for the transduction of Wnt signaling pathway. However, the 19 members of Wnts in humans imply a daunting complexity of Wnt signaling and biological effects, and our understanding of their roles in CRC tumorigenesis is still quite rudimentary. This review will give an overview of the structural characteristics and maturation process of Wnts. The expression pattern of all human Wnts in CRC tissues, including Wnt1, Wnt2, Wnt2b, Wnt3, Wnt3a, Wnt4, Wnt5a, Wnt5b, Wnt6, Wnt7a, Wnt7b, Wnt8a, Wnt8b, Wnt9a, Wnt9b, Wnt10a, Wnt10b, Wnt11, and Wnt16, and their relationship with the tumorigenesis and the progression of CRC will be specifically summarized separately. Despite certain challenges, Wnt-based therapeutics for CRC emerge continuously and some are now in clinical trials. In conclusion, a deep understanding of Wnts is very helpful for a better management of this disease.

Retracted Article: Panax notoginseng saponins regulate VEGF to suppress esophageal squamous cell carcinoma progression via DVL3-mediated Wnt/β-catenin signaling

PNS regulate VEGF expression to suppress ESCC progression via the DVL3-mediated Wnt/β-catenin signaling pathway.

HIF-1α/Wnt signaling-dependent control of gene transcription regulates neuronal differentiation of glioblastoma stem cells

HIF-1α has been suggested to interplay with Wnt signaling components in order to activate a neuronal differentiation process in both normal brain and glioblastoma (GBM). Based on these data, we explored the molecular mechanisms underlying the observed capability of GBM cells to acquire a neuronal phenotype upon Wnt signaling stimulation and how the microenvironment, particularly hypoxia, modulates this process.

Methods: here, the employment of ChIP-seq techniques together with co-immunoprecipitation approaches allowed to reconstruct the molecular interactions responsible for activating specific pro-differentiating transcriptional programs in GBM cells. Moreover, gene silencing/over-expression approaches coupled with the functional analysis of cell phenotype were applied to confirm ChIP-driven hypotheses. Finally, we combined the use of publicly available gene expression datasets with protein expression data by immunohistochemistry to test the clinical relevance of obtained results.

Results: our data clearly suggest that HIF-1α is recruited by the β-catenin/TCF1 complex to foster neuronal differentiation gene transcription in hypoxic GBM cells. Conversely, at higher oxygen levels, the increased expression of TCF4 exerts a transcriptional inhibitory function on the same genomic regions, thus counteracting differentiation. Moreover, we demonstrate the existence of a positive correlation between the expression levels of HIF-1α, TCF1 and neuronal phenotype in GBM tumors, accompanied by the over-expression of several Wnt signaling components, finally affecting patient prognosis.

Conclusion: we unveiled a peculiar mechanism by which TCF1 and HIF-1α can induce a reminiscent neuronal differentiation of hypoxic GBM cells, which is hampered, in normoxia, by high levels of TCF4, thus not only de facto controlling the balance between differentiation and stemness, but also impacting on intra-tumoral heterogeneity and eventually patient outcome.

Long noncoding RNA GAS5 inhibits angiogenesis and metastasis of colorectal cancer through the Wnt/β-catenin signaling pathway

OBJECTIVE

Angiogenesis plays a key role in the tumorigenesis and progression of colorectal cancer (CRC). In this study, we investigated the effect of long noncoding RNA (lncRNA) GAS5 on the angiogenesis, invasion, and metastasis of CRC, and the involvement of the Wnt/β-catenin signaling pathway.

METHODS

CRC tissues and adjacent normal tissues were collected from 52 patients with CRC. GAS5 expression was determined in vivo and in vitro by real-time quantitative polymerase chain reaction (RT-qPCR). Then RT-qPCR and Western blot were used to identify expression of key genes of Wnt/β-catenin signaling pathway. CRC cells with lowest GAS5 expression were selected and subjected to si-GAS5, oe-GAS5, or XAV939 to validate the effect of GAS5 and Wnt/β-catenin signaling pathway on CRC cell activities. The activation of Wnt/β-catenin signaling pathway was determined in response to GAS5. Subcutaneous tumor growth and microvascular density were observed in nude mice, in which in vivo metastasis was observed following tail vein injection of CRC cells.

RESULTS

Initially, poor expression of GAS5 was observed in CRC tissues and cells. Upregulated GAS5 repressed CRC cell invasion and migration in vitro, as well as subcutaneous tumor growth, angiogenesis, and liver metastases in vivo. Furthermore, the Wnt/β-catenin signaling pathway was determined to be activated in CRC tissues and cells, while its activation was inhibited by GAS5. The Wnt/β-catenin signaling pathway promoted the CRC cell invasion and migration in vitro, subcutaneous tumor growth, angiogenesis and, liver metastases in vivo.

CONCLUSION

Taken together, the results of the study conclude that lncRNA GAS5 inhibited the activation of the Wnt/β-catenin signaling pathway, thereby suppressing the angiogenesis, invasion, and metastasis of CRC.

HIF-1α-induced miR-23a∼27a∼24 cluster promotes colorectal cancer progression via reprogramming metabolism

Tumor cells switch metabolic profile from oxidative phosphorylation to glycolysis in a hypoxic environment for survival and proliferation. The mechanisms governing this metabolic switch, however, remain incompletely understood. Here, we show that three miRNAs in the miR-23a∼27a∼24 cluster, miR-23a, miR-27a and miR-24, are the most upregulated miRNA cluster in colorectal cancer (CRC) under hypoxia. Gain- and loss-of-function assays, a human glucose metabolism array and gene pathway analyses confirm that HIF-1α-induced miR-23a∼27a∼24 cluster collectively regulate glucose metabolic network through regulating various metabolic pathways and targeting multiple tricarboxylic acid cycle (TCA)-related genes. In specific, miR-24/VHL/HIF-1α in CRC form a double-negative feedback loop, which in turn, promotes the cellular transition to the 'high HIF-1α/miR-24 and low VHL' state and facilitates cell survival. Our findings reveal that the miR-23a∼27a∼24 cluster is critical regulator switching CRC metabolism from oxidative phosphorylation to glycolysis, and controlling their expression can suppress colorectal cancer progression.

Adenoviral delivery of VHL suppresses bone sarcoma cell growth through inhibition of Wnt/β-catenin signaling

The VHL tumor suppressor gene is frequently inactivated in several human tumors, including bone sarcomas. We previously identified that reduced expression of VHL protein is implicated in sarcomagenesis. However, the underlying biological functions of restored VHL protein expression have not been clearly elucidated in bone sarcomas. Here we initially constructed a recombinant adenovirus 5-VHL vector (Ad5-VHL) and evaluated its expression in bone sarcomas, and antitumor activity in vitro and in vivo. We found that the adenovirus-mediated increase of VHL significantly suppresses bone sarcoma cell growth, attributed to induction of apoptosis mediated by increased caspase-3 activity and modulated Bcl-2 protein family. This suppression effect involves inhibition of Wnt/β-catenin signaling and upregulation of GSK-3β. Moreover, Ad5-VHL showed a dramatic antitumor effect on a chondrosarcoma xenograft model. These findings establish that Ad5-VHL suppresses bone sarcoma cell growth by inhibiting Wnt/β-catenin signaling, and may be a novel target for gene-based therapy of bone sarcomas.

Administration of Hypoxia-Activated Prodrug Evofosfamide after Conventional Adjuvant Therapy Enhances Therapeutic Outcome and Targets Cancer-Initiating Cells in Preclinical Models of Colorectal Cancer

Purpose: Cancer-initiating cells (C-IC) have been described in multiple cancer types, including colorectal cancer. C-ICs are defined by their capacity to self-renew, thereby driving tumor growth. C-ICs were initially thought to be static entities; however, recent studies have determined these cells to be dynamic and influenced by microenvironmental cues such as hypoxia. If hypoxia drives the formation of C-ICs, then therapeutic targeting of hypoxia could represent a novel means to target C-ICs.Experimental Design: Patient-derived colorectal cancer xenografts were treated with evofosfamide, a hypoxia-activated prodrug (HAP), in combination with 5-fluorouracil (5-FU) or chemoradiotherapy (5-FU and radiation; CRT). Treatment groups included both concurrent and sequential dosing regimens. Effects on the colorectal cancer-initiating cell (CC-IC) fraction were assessed by serial passage in vivo limiting dilution assays. FAZA-PET imaging was utilized as a noninvasive method to assess intratumoral hypoxia.Results: Hypoxia was sufficient to drive the formation of CC-ICs and colorectal cancer cells surviving conventional therapy were more hypoxic and C-IC-like. Using a novel approach to combination therapy, we show that sequential treatment with 5-FU or CRT followed by evofosfamide not only inhibits tumor growth of xenografts compared with 5-FU or CRT alone, but also significantly decreases the CC-IC fraction. Furthermore, noninvasive FAZA-PET hypoxia imaging was predictive of a tumor's response to evofosfamide.Conclusions: Our data demonstrate a novel means to target the CC-IC fraction by adding a HAP sequentially after conventional adjuvant therapy, as well as the use of FAZA-PET as a biomarker for hypoxia to identify tumors that will benefit most from this approach. Clin Cancer Res; 24(9); 2116-27. ©2018 AACR.

Selenium targets resistance biomarkers enhancing efficacy while reducing toxicity of anti-cancer drugs: preclinical and clinical development

Selenium (Se)-containing molecules exert antioxidant properties and modulate targets associated with tumor growth, metastasis, angiogenesis, and drug resistance. Prevention clinical trials with low-dose supplementation of different types of Se molecules have yielded conflicting results. Utilizing several xenograft models, we earlier reported that the enhanced antitumor activity of various chemotherapeutic agents by selenomethione and Se-methylselenocysteine in several human tumor xenografts is highly dose- and schedule-dependent. Further, Se pretreament offered selective protection of normal tissues from drug-induced toxicity, thereby allowing higher dosing than maximum tolerated doses. These enhanced therapeutic effects were associated with inhibition of hypoxia-inducible factor 1- and 2-alpha (HIF1α, HIF2α) protein, nuclear factor (erythyroid-derived 2)-like 2 (Nrf2) and pair-related homeobox-1 (Prx1) transcription factors, downregulation of oncogenic- and upregulation of tumor suppressor miRNAs. This review provides: 1) a brief update of clinical prevention trials with Se; 2) advances in the use of specific types, doses, and schedules of Se that selectively modulate antitumor activity and toxicity of anti-cancer drugs; 3) identification of targets selectively modulated by Se; 4) plasma and tumor tissue Se levels achieved after oral administration of Se in xenograft models and cancer patients; 5) development of a phase 1 clinical trial with escalating doses of orally administered selenomethionine in sequential combination with axitinib to patients with advanced clear cell renal cell carcinoma; and 6) clinical prospects for future therapeutic use of Se in combination with anticancer drugs.

"Vessels in the Storm": Searching for Prognostic and Predictive Angiogenic Factors in Colorectal Cancer

High expectations are placed upon anti-angiogenic compounds for metastatic colorectal cancer (mCRC), the first malignancy for which such type of treatment has been approved. Indeed, clinical trials have confirmed that targeting the formation of new vessels can improve in many cases clinical outcomes of mCRC patients. However, current anti-angiogenic drugs are far from obtaining the desirable or expected curative results. Many are the factors probably involved in such disappointing results, but particular attention is currently focused on the validation of biomarkers able to improve the direction of treatment protocols. Because clinical studies have clearly demonstrated that serum or tissue concentration of some angiogenic factors is associated with the evolution of the disease of mCRC patients, they are currently explored as potential biomarkers of prognosis and of tumor response to therapy. However, the complex biology underlying CRC -induced angiogenesis is a hurdle in finding rapid solutions. The aim of this review was to explore molecular mechanisms that determine the formation of tumor-associated vessels during CRC progression, and to discuss the potential role of angiogenic factors as diagnostic, prognostic and predictive biomarkers in CRC.

Expression of VHL tumor suppressor mRNA and miR-92a in papillary thyroid carcinoma and their correlation with clinical and pathological parameters

A growing body of evidence suggests a role of the von Hippel-Lindau (VHL) tumor suppressor gene in the progression of papillary thyroid carcinoma (PTC). Our previous study of VHL in PTCs showed that lower VHL expression was associated with aggressive tumor features, but we found no evidence for VHL downregulation through common genetic or epigenetic modifications. Several studies pointed to a role of microRNA-92a (miR-92a) in the regulation of VHL expression in different cancers. In the present study, we examined the expression levels of VHL mRNA and miR-92a in 42 pairs of PTCs and matched non-tumor thyroid tissues by means of quantitative RT-PCR. We explored the correlation between them and their association with clinicopathological parameters. The results revealed that both VHL and miR-92a were either up- or downregulated in PTCs compared to corresponding non-tumor tissues. On univariate analysis, lower VHL levels were significantly associated with extrathyroid spread (P = 0.022) and capsular invasion (P = 0.032). Multivariate analysis confirmed the association of low VHL with extrathyroid spread (OR 0.246, 95% CI 0.069-0.872, P = 0.038). Higher miR-92a among PTC tissues associated with the presence of nodal metastases (univariate analysis: P = 0.012; multivariate: OR 4.703, 95% CI 1.109-19.938, P = 0.036). A negative correlation between VHL and miR-92a was observed in a subgroup of PTCs having vascular invasion (P = 0.033, r = - 0.673). The data here reported demonstrate that the expression of both VHL and miR-92a is deregulated in PTC tissues and that in some PTCs they may have opposite roles. These roles, as well as their diagnostic and/or prognostic utility, remain to be clarified.

Elevated d-2-hydroxyglutarate during colitis drives progression to colorectal cancer

d-2-hydroxyglutarate (D2HG) is produced in the tricarboxylic acid cycle and is quickly converted to α-ketoglutarate by d-2-hydroxyglutarate dehydrogenase (D2HGDH). In a mouse model of colitis-associated colon cancer (CAC), urine level of D2HG during colitis correlates positively with subsequent polyp counts and severity of dysplasia. The i.p. injection of D2HG results in delayed recovery from colitis and severe tumorigenesis. The colonic expression of D2HGDH is decreased in ulcerative colitis (UC) patients at baseline who progress to cancer. Hypoxia-inducible factor (Hif)-1α is a key regulator of D2HGDH transcription. Our study identifies urine D2HG and tissue D2HGDH expression as biomarkers to identify patients at risk for progressing from colitis to cancer. The D2HG/D2HGDH pathway provides potential therapeutic targets for the treatment of CAC.

HIF-1α/Ascl2/miR-200b regulatory feedback circuit modulated the epithelial-mesenchymal transition (EMT) in colorectal cancer cells

We have reported that Achaete scute-like 2 (Ascl2) transcriptionally repressed miR-200 family members and affected the epithelial-mesenchymal transition (EMT)-mesenchymal-epithelial transition (MET) plasticity in colorectal cancer (CRC) cells. However, little is known about the regulation of the Ascl2/miR-200 axis. Here, we found that hypoxia inducible factor-1α (HIF-1α) mRNA levels were positively correlated with Ascl2 mRNA levels and inversely correlated with miR-200b in CRC samples. Mechanistically, we showed that Ascl2 was a downstream target of HIF-1α and had a critical role in the EMT phenotype induced by hypoxia or HIF-1α over-expression. Hypoxia or HIF-1α over-expression activated Ascl2 expression in CRC cells in a direct transcriptional mechanism via binding with the hypoxia-response element (HRE) at the proximal Ascl2 promoter. HIF-1α-induced Ascl2 expression repressed miR-200b expression to induce EMT occurrence. Furthermore, we found HIF-1α was a direct target of miR-200b. MiR-200b bound with the 3'-UTR of HIF-1α in CRC cells. HIF-1α/Ascl2/miR-200b regulatory feedback circuit modulated the EMT-MET plasticity of CRC cells. Our results confirmed a novel HIF-1α/Ascl2/miR-200b regulatory feedback circuit in modulating EMT-MET plasticity of CRC cells, which could serve as a possible therapeutic target.

Hypoxia and Inflammation in Cancer, Focus on HIF and NF-κB

Cancer is often characterised by the presence of hypoxia and inflammation. Paramount to the mechanisms controlling cellular responses under such stress stimuli, are the transcription factor families of Hypoxia Inducible Factor (HIF) and Nuclear Factor of κ-light-chain-enhancer of activated B cells (NF-κB). Although, a detailed understating of how these transcription factors respond to their cognate stimulus is well established, it is now appreciated that HIF and NF-κB undergo extensive crosstalk, in particular in pathological situations such as cancer. Here, we focus on the current knowledge on how HIF is activated by inflammation and how NF-κB is modulated by hypoxia. We summarise the evidence for the possible mechanism behind this activation and how HIF and NF-κB function impacts cancer, focusing on colorectal, breast and lung cancer. We discuss possible new points of therapeutic intervention aiming to harness the current understanding of the HIF-NF-κB crosstalk.

Hypoxia activates Wnt/β-catenin signaling by regulating the expression of BCL9 in human hepatocellular carcinoma

The Wnt/β-catenin signaling is abnormally activated in the progression of hepatocellular carcinoma (HCC). BCL9 is an essential co-activator in the Wnt/β-catenin signaling. Importantly, BCL9 is absent from tumors originating from normal cellular counterparts and overexpressed in many cancers including HCC. But the mechanism for BCL9 overexpression remains unknown. Ample evidence indicates that hypoxia inducible factors (HIFs) play a role in the development of HCC. It was found in our study that BCL9 was overexpressed in both primary HCC and bone metastasis specimens; loss of BCL9 inhibited the proliferation, migration and angiogenesis of HCC; and that that hypoxia mechanically induced the expression of BCL9. BCL9 induction under the hypoxic condition was predominantly mediated by HIF-1α but not HIF2α. In vitro evidence from xenograft models indicated that BCL9 promoter/gene knockout inhibited HCC tumor growth and angiogenesis. Notably, we found that BCL9 and HIF-1α were coordinately regulated in human HCC specimen. The above findings suggest that hypoxia may promote the expression of BCL9 and associate with the development of HCC. Specific regulation of BCL9 expression by HIF-1α may prove to be an underlying crosstalk between Wnt/β-catenin signaling and hypoxia signaling pathways.

Hypoxia pathway and hypoxia-mediated extensive extramedullary hematopoiesis are involved in ursolic acid's anti-metastatic effect in 4T1 tumor bearing mice

Hypoxic in the tumor mass is leading to the myeloproliferative-like disease (leukemoid reaction) and anemia of body, which characterized by strong extensive extramedullary hematopoiesis (EMH) in spleen. As the key transcription factor of hypoxia, hypoxia-inducible factor-1 (HIF-1) activates the expression of genes essential for EMH processes including enhanced blood cell production and angiogenesis. We found ursolic acid (UA), a natural pentacyclic triterpenoid carboxylic acid, inhibited growth of breast cancer both in vivo and in vitro. The suppression was mediated through the inhibition of multiple cell pathways linked to inflammation, proliferation, angiogenesis, and metastasis. UA also suppressed the leukemoid reaction and the EMH phenomenon of the tumor bearing mice without any significant suppression on body weight (i.p. by 20 mg/kg for 28 days). This is associated with the significant decrease in white blood cells (WBC), platelets (PLT) and spleen weight. During this process, we also detected the down-regulation of cell proliferative genes (PCNA, and β-catenin), and metastatic genes (VEGF, and HIF-1α), as well as the depression of nuclear protein intensity of HIF-1α. Furthermore, the expression of E2F1, p53 and MDM2 genes were increased in UA group when the VEGF and HIF-1α was over-expressed. Cancer cells were sensitive to UA treating after the silencing of HIF-1α and the response of Hypoxic pathway reporter to UA was suppressed when HIF-1α was over expressed. Overall, our results from experimental and predictive studies suggest that the anticancer activity of UA may be at least in part caused by suppressing the cancer hypoxia and hypoxia-mediated EMH.

Increased Expression of Thymosin β4 Is Independently Correlated with Hypoxia Inducible Factor-1α (HIF-1α) and Worse Clinical Outcome in Human Colorectal Cancer

Background

Thymosin β₄ is a multi-functional hormone-like polypeptide, being involved in cell migration, angiogenesis, and tumor metastasis. This study was undertaken to clarify the clinicopathologic implications of thymosin β₄ expression in human colorectal cancers (CRCs).

Methods

We investigated tissue sections from 143 patients with CRC by immunohistochemistry. In addition, we evaluated the expression patterns and the clinico-pathological significance of thymosin β₄ expression in association with hypoxia inducible factor-1α (HIF-1α) expression in the CRC series.

Results

High expression of thymosin β₄ was significantly correlated with lymphovascular invasion, invasion depth, regional lymph node metastasis, distant metastasis, and TNM stage. Patients with high expression of thymosin β₄ showed poor recurrence-free survival (p = .001) and poor overall survival (p = .005) on multivariate analysis. We also found that thymosin β₄ and HIF-1α were overexpressed and that thymosin β₄ expression increased in parallel with HIF-1α expression in CRC.

Conclusions

A high expression level of thymosin β₄ indicates poor clinical outcomes and may be a useful prognostic factor in CRC. Thymosin β₄ is functionally related with HIF-1α and may be a potentially valuable biomarker and possible therapeutic target for CRC.

Correlation analysis of VHL and Jade-1 gene expression in human renal cell carcinoma

Objective

The aim of this study was to investigate the correlation of von Hippel-Lindau tumor suppressor (VHL) mRNA expression and jade family PHD finger 1 (Jade-1) gene expression in patients with renal cell carcinoma (RCC). Another aim of this study was to analyze the relationship of these two genes with clinicalpathological features of the RCC patients.

Methods

A total of 75 RCC patients who received surgically therapy in our hospital were included. All patients had complete pathological data. The expression of VHL/Jade-1 was determined by real-time polymerase chain reaction (RT-PCR).

Results

VHL and Jade-1 were both obviously downregulated in RCC tissues than that of the matched normal tissues, and both negatively correlated with tumor size as well as tumor grade. And we found a fine association of VHL gene expression with Jade-1.

Conclusion

VHL/Jade-1 exhibited significantly decreased expression in RCC tissues and was closely related to the clinical prognosis of patients. The finding of VHL expression positively correlated with Jade-1 expression shed light and provided crucial evidence on the connection of VHL protein with Wnt/b-catenin pathway.

Expression of hypoxia-inducible factor-1α affects tumor proliferation and antiapoptosis in surgically resected lung cancer

Hypoxia-inducible factor (HIF)-1 is a transcription factor that allows cells to adapt to hypoxic situations. HIF-1 is known to control tissue proliferation, antiapoptosis, angiogenesis and glucose metabolism. Furthermore, HIF-1 is involved in the growth of numerous cancer types. The present study aimed to examine the expression of HIF-1α immunohistochemically in resected lung cancers. The present study included 216 consecutive patients with lung cancer who underwent resection between April 2013 and January 2015. The patients' clinicopathological data were summarized, including imaging findings, tumor pathological characteristics, and the patient's age, sex and smoking status. The intratumoral expression of HIF-1α, survivin, c-Myc and the Ki-67 proliferation index were evaluated immunohistochemically. The patients were divided into two groups, according to the expression of HIF-1α (low vs. high) and the clinicopathological characteristics of these groups were compared. It was revealed that HIF-1α expression was significantly associated with ground glass opacity ratio, maximum standardized uptake value index, histological type (squamous cell carcinoma), differentiation and lymphatic invasion. Regarding the immunohistochemical findings, HIF-1α expression was significantly correlated with the expression levels of c-Myc (P<0.01) and survivin (P<0.01). Furthermore, the Ki-67 proliferation index was significantly higher in high-HIF-1α tumors compared with in low-HIF-1α tumors (P=0.01). The multivariate analysis identified squamous cell carcinoma, high SUVmax and lymphatic invasion as significant and independent factors for high HIF-1α expression. In conclusion, HIF-1 was highly expressed in certain subgroups of lung cancer with specific histopathology and images. HIF-1α expression was associated with tumor proliferation and antiapoptosis in lung cancer.

Glucose Transporter 1 (SLC2A1) and Vascular Endothelial Growth Factor A (VEGFA) Predict Survival After Resection of Colorectal Cancer Liver Metastasis

OBJECTIVE

To investigate the individual and combined prognostic value of HIF1α, SLC2A1, and vascular endothelial growth factor A (VEGFA) in a multi-institutional cohort of patients with resected colorectal cancer liver metastasis (CRCLM).

BACKGROUND

In the majority of patients with CRCLM, resection seems not to be curative, despite its curative intent. Overexpression of hypoxia-inducible factor 1α (HIF1α), glucose transporter 1 (SLC2A1; also known as GLUT1), and VEGFA has been associated with tumor progression and poor prognosis of patients with colorectal cancer (CRC).

METHODS

Tissue microarrays were generated using CRCLM and patient-matched primary CRC from patients who underwent CRCLM resection between 1990 and 2010. Prognostic value of HIF1α, SLC2A1, and VEGFA was determined by immunohistochemistry. A 500-fold cross-validated hazard rate ratio (HRRav) for overall survival was calculated.

RESULTS

HIF1α, SLC2A1, and VEGFA expression could be evaluated in 328, 350, and 335 patients, respectively. High SLC2A1 expression was associated with good prognosis (HRRav, 0.67; P (HRR >1)  < 0.01) and high VEGFA expression to poor prognosis (HRRav, 1.84; P (HRR < 1)  = 0.02), also after multivariate analysis including established clinicopathological prognostic variables (HRRav, 0.67; P (HRR > 1)  < 0.01 and HRRav, 1.50; P (HRR < 1)  = 0.02, respectively). SLC2A1 showed prognostic value particularly in patients treated with systemic therapy (P < 0.01), whereas the prognostic value of VEGFA expression was mainly observed in patients not treated with systemic therapy (P < 0.01). Prognosis was especially poor in patients with both low SLC2A1 and high VEGFA expression (P < 0.01). HIF1α expression was not associated with survival.

CONCLUSIONS

SLC2A1 and VEGFA expression are prognostic molecular biomarkers for patients with CRCLM with added value to established clinicopathological variables.

Epigenetic effects of selenium and their implications for health

Alterations of epigenetic marks are linked to normal development and cellular differentiation as well as to the progression of common chronic diseases. The plasticity of these marks provides potential for disease therapies and prevention strategies. Macro- and micro-nutrients have been shown to modulate disease risk in part via effects on the epigenome. The essential micronutrient selenium affects human health outcomes, e.g., cancers, cardiovascular and autoimmune diseases, via selenoproteins and through a range of biologically active dietary selenocompounds and metabolism products thereof. This review provides an assessment of the current literature regarding epigenetic effects of dietary and synthetic selenocompounds, which include the modulation of marks and editors of epigenetic information and interference with one-carbon metabolism, which provides the methyl donor for DNA methylation. The relevance of a selenium-epigenome interaction for human health is discussed, and we also indicate where future studies will be helpful to gain a deeper understanding of epigenetic effects elicited by selenium.

Hypoxia provokes base excision repair changes and a repair-deficient, mutator phenotype in colorectal cancer cells

Regions of acute and chronic hypoxia exist within solid tumors and can lead to increased rates of mutagenesis and/or altered DNA damage and repair protein expression. Base excision repair (BER) is responsible for resolving small, non-helix-distorting lesions from the genome that potentially cause mutations by mispairing or promoting DNA breaks during replication. Germline and somatic mutations in BER genes, such as MutY Homolog (MUTYH/MYH) and DNA-directed polymerase (POLB), are associated with increased risk of colorectal cancer. However, very little is known about the expression and function of BER proteins under hypoxic stress. Using conditions of chronic hypoxia, decreased expression of BER proteins was observed because of a mechanism involving suppressed BER protein synthesis in multiple colorectal cancer cell lines. Functional BER was impaired as determined by MYH- and 8-oxoguanine (OGG1)-specific glycosylase assays. A formamidopyrimidine-DNA glycosylase (Fpg) Comet assay revealed elevated residual DNA base damage in hypoxic cells 24 hours after H2O2 treatment as compared with normoxic controls. Similarly, high-performance liquid chromatography analysis demonstrated that 8-oxo-2'-deoxyguanosine lesions were elevated in hypoxic cells 3 and 24 hours after potassium bromate (KBrO3) treatment when compared with aerobic cells. Correspondingly, decreased clonogenic survival was observed following exposure to the DNA base damaging agents H2O2 and MMS, but not to the microtubule interfering agent paclitaxel. Thus, a persistent downregulation of BER components by the microenvironment modifies and facilitates a mutator phenotype, driving genetic instability and cancer progression.

IMPLICATIONS

Aberrant BER is a contributing factor for the observed genetic instability in hypoxic tumor cells.

Inflammatory cues acting on the adult intestinal stem cells and the early onset of cancer (review)

The observation that cancer often arises at sites of chronic inflammation has prompted the idea that carcinogenesis and inflammation are deeply interwoven. In fact, the current literature highlights a role for chronic inflammation in virtually all the steps of carcinogenesis, including tumor initiation, promotion and progression. The aim of the present article is to review the current literature on the involvement of chronic inflammation in the initiation step and in the very early phases of tumorigenesis, in a type of cancer where adult stem cells are assumed to be the cells of origin of neoplasia. Since the gastrointestinal tract is regarded as the best-established model system to address the liaison between chronic inflammation and neoplasia, the focus of this article will be on intestinal cancer. In fact, the anatomy of the intestinal epithelial lining is uniquely suited to study adult stem cells in their niche, and the bowel crypt is an ideal developmental biology system, as proliferation, differentiation and cell migration are all distributed linearly along the long axis of the crypt. Moreover, crypt stem cells are regarded today as the most likely targets of neoplastic transformation in bowel cancer. More specifically, the present review addresses the molecular mechanisms whereby a state of chronic inflammation could trigger the neoplastic process in the intestine, focusing on the generation of inflammatory cues evoking enhanced proliferation in cells not initiated but at risk of neoplastic transformation because of their stemness. Novel experimental approaches, based on triggering an inflammatory stimulus in the neighbourhood of adult intestinal stem cells, are warranted to address some as yet unanswered questions. A possible approach, the targeted transgenesis of Paneth cells, may be aimed at 'hijacking' the crypt stem cell niche from a status characterized by the maintenance of homeostasis to local chronic inflammation, with the prospect of initiating neoplastic transformation in that site.

Distinct profile of HIF1α, PTCH, EphB2, or DNA repair protein expression and BRAF mutation in colorectal serrated adenoma

BACKGROUND AND AIMS

The serrated colorectal carcinoma (CRC) as proposed to arise from serrated adenoma (SA) is characterized by upregulation of HIF1α, suppression of PTCH or EphB2, loss of DNA repair proteins, and BRAF mutation. The aim of this study was to evaluate alterations of these candidates involved in the serrated pathway in colorectal polyps.

METHODS

We analyzed immunoreactivity of these proteins, methylation of PTCH and EphB2, and mutation of BRAF and Kras in sessile SAs (SSAs; n = 32), traditional SAs (n = 28), hyperplastic polyps (HPs; n = 24), and conventional adenomas (ADs; n = 21).

RESULTS

Increase of nuclear HIF1α expression was more frequent in SA than HP, but less frequent in SA than AD (P < 0.001). Increase of PTCH expression was not found in SSA or HP, but was evident in about half of traditional SA and all AD (P < 0.001). Decrease of EphB2 expression was more prominent in SA than HP or AD (P ≤ 0.005). Loss of hMLH1 and MGMT expression were most frequent in SSA (P < 0.001). Loss of hMSH2 showed more pronounced in SA and HP than AD (P ≤ 0.004). Methylations of PTCH and EphB2 were rare in all categories. BRAF mutation harbored frequently in SA, but not AD; only AD harbored Kras mutation.

CONCLUSIONS

This work provides evidence of similarity of HIF1α, EphB2 or DNA repair proteins expression, and BRAF mutation in serrated CRCs and their precursors, especially SSA, compared with AD and HP.

Wnt signaling directs a metabolic program of glycolysis and angiogenesis in colon cancer

Much of the mechanism by which Wnt signaling drives proliferation during oncogenesis is attributed to its regulation of the cell cycle. Here, we show how Wnt/β-catenin signaling directs another hallmark of tumorigenesis, namely Warburg metabolism. Using biochemical assays and fluorescence lifetime imaging microscopy (FLIM) to probe metabolism in vitro and in living tumors, we observe that interference with Wnt signaling in colon cancer cells reduces glycolytic metabolism and results in small, poorly perfused tumors. We identify pyruvate dehydrogenase kinase 1 (PDK1) as an important direct target within a larger gene program for metabolism. PDK1 inhibits pyruvate flux to mitochondrial respiration and a rescue of its expression in Wnt-inhibited cancer cells rescues glycolysis as well as vessel growth in the tumor microenvironment. Thus, we identify an important mechanism by which Wnt-driven Warburg metabolism directs the use of glucose for cancer cell proliferation and links it to vessel delivery of oxygen and nutrients.

Metastasis-associated gene, mag-1 improves tumour microenvironmental adaptation and potentiates tumour metastasis

Metastasis is a major cause of death from malignant diseases, and the underlying mechanisms are still largely not known. A detailed probe into the factors which may regulate tumour invasion and metastasis contributes to novel anti-metastatic therapies. We previously identified a novel metastasis-associated gene 1 (mag-1) by means of metastatic phenotype cloning. Then we characterized the gene expression profile of mag-1 and showed that it promoted cell migration, adhesion and invasion in vitro. Importantly, the disruption of mag-1 via RNA interference not only inhibited cellular metastatic behaviours but also significantly reduced tumour weight and restrained mouse breast cancer cells to metastasize to lungs in spontaneous metastatic assay in vivo. Furthermore, we proved that mag-1 integrates dual regulating mechanisms through the stabilization of HIF-1α and the activation of mTOR signalling pathway. We also found that mag-1-induced metastatic promotion could be abrogated by mTOR specific inhibitor, rapamycin. Taken together, the findings identified a direct role that mag-1 played in metastasis and implicated its function in cellular adaptation to tumour microenvironment.

Identification of the angiogenic gene signature induced by EGF and hypoxia in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is characterised by hypoxia, which activates gene transcription through hypoxia-inducible factors (HIF), as well as by expression of epidermal growth factor (EGF) and EGF receptors, targeting of which has been demonstrated to provide therapeutic benefit in CRC. Although EGF has been demonstrated to induce expression of angiogenic mediators, potential interactions in CRC between EGF-mediated signalling and the hypoxia/HIF pathway remain uncharacterised.

METHODS

PCR-based profiling was applied to identify angiogenic genes in Caco-2 CRC cells regulated by hypoxia, the hypoxia mimetic dimethyloxallylglycine (DMOG) and/or EGF. Western blotting was used to determine the role of HIF-1alpha, HIF-2alpha and MAPK cell signalling in mediating the angiogenic responses.

RESULTS

We identified a total of 9 angiogenic genes, including angiopoietin-like (ANGPTL) 4, ephrin (EFNA) 3, transforming growth factor (TGF) β1 and vascular endothelial growth factor (VEGF), to be upregulated in a HIF dependent manner in Caco-2 CRC cells in response to both hypoxia and the hypoxia mimetic dimethyloxallylglycine (DMOG). Stimulation with EGF resulted in EGFR tyrosine autophosphorylation, activation of p42/p44 MAP kinases and stabilisation of HIF-1α and HIF-2α proteins. However, expression of 84 angiogenic genes remained unchanged in response to EGF alone. Crucially, addition of DMOG in combination with EGF significantly increased expression of a further 11 genes (in addition to the 9 genes upregulated in response to either DMOG alone or hypoxia alone). These additional genes included chemokines (CCL-11/eotaxin-1 and interleukin-8), collagen type IV α3 chain, integrin β3 chain, TGFα and VEGF receptor KDR.

CONCLUSION

These findings suggest that although EGFR phosphorylation activates the MAP kinase signalling and promotes HIF stabilisation in CRC, this alone is not sufficient to induce angiogenic gene expression. In contrast, HIF activation downstream of hypoxia/DMOG drives expression of genes such as ANGPTL4, EFNA3, TGFβ1 and VEGF. Finally, HIF activation synergises with EGF-mediated signalling to additionally induce a unique sub-group of candidate angiogenic genes. Our data highlight the complex interrelationship between tumour hypoxia, EGF and angiogenesis in the pathogenesis of CRC.

Transcriptional upregulation of HIF-1α by NF-κB/p65 and its associations with β-catenin/p300 complexes in endometrial carcinoma cells

The hypoxia-inducible factor (HIF)-1α, which has a major role in cell adaptation to hypoxia, is mainly regulated at post-translational levels. Recently, HIF-1α mRNA was also shown to be upregulated by several signal pathways under normoxic conditions. Here we focused on relationships of HIF-1α with NF-κB and β-catenin signaling in endometrial carcinomas (Em Cas). Long-term exposure of Ishikawa cells to cobalt chloride (CoCl2), which is known to mimic the effect of hypoxia, caused a decrease in the growth, along with increased HIF-1α protein but not mRNA expression. In contrast, short-term exposure resulted in a rapid and transient increase in HIF-1α mRNA expression along with stabilization of nuclear NF-κB/p65 (p65). Transfection of p65 increased HIF-1α expression through activation of the promoter, whereas overexpression of HIF-1α also activated NF-κB-dependent transcription, indicating the existence of a positive feedback loop. In addition, HIF-1α was indirectly associated with nuclear β-catenin through interactions with p300, leading to slight enhancement of both HIF-1α- and β-catenin-mediated transcriptional activity. In clinical samples, biphasic upregulation of HIF-1α expression was observed in normal endometrial glandular components during the menstrual cycle, with the labeling indices showing significantly higher values in the early secretory stage. Significantly higher values for phosphorylated p65 and nuclear β-catenin were also observed in HIF-1α-positive than -negative lesions of Em Cas, in contrast to significantly lower Ki-67 status. These data therefore suggest that transcriptional associations with HIF-1α and NF-κB, as well as β-catenin/p300 complexes, may contribute to modulation of changes in tumor cell kinetics in response to a hypoxic condition in Em Cas.

Regulation of E2F1 by the von Hippel-Lindau tumour suppressor protein predicts survival in renal cell cancer patients

Biallelic mutations of the von Hippel-Lindau (VHL) gene are the most common cause of sporadic and inherited renal cell carcinoma (RCC). Loss of VHL has been reported to affect cell proliferation by deregulating cell cycle-associated proteins. We report that the VHL gene product (pVHL) inhibits E2F1 expression at both mRNA and protein level in zebrafish and human RCC cells, while loss of VHL increases E2F1 expression in patient kidney tumour tissue and RCC cells, resulting in a delay of cell cycle progression. RCCs from von Hippel-Lindau patients with known germline VHL mutations express significantly more E2F1 compared to sporadic RCCs with either clear-cell (cc) or non-cc histology. Analysis of 138 primary RCCs reveals that E2F1 expression is significantly higher in tumours with a diameter ≤7 cm and with a favourable American Joint Committee on Cancer (AJCC) stage. The expression of E2F1 in RCC significantly correlates with p27 expression, suggesting that increased expression of E2F1 in RCC induces tumour cell senescence via p27. Cox regression analysis shows significant prediction of E2F1 expression for disease-free survival and overall survival, implying that E2F1 expression in kidney tumour is a novel prognostic factor for patients with RCC.

Multitargeted low-dose GLAD combination chemoprevention: a novel and promising approach to combat colon carcinogenesis

Preclinical studies have shown that gefitinib, licofelone, atorvastatin, and α-difluoromethylornithine (GLAD) are promising colon cancer chemopreventive agents. Because low-dose combination regimens can offer potential additive or synergistic effects without toxicity, GLAD combination was tested for toxicity and chemopreventive efficacy for suppression of intestinal tumorigenesis in adenomatous polyposis coli (APC)(Min/+) mice. Six-week-old wild-type and APC(Min/+) mice were fed modified American Institute of Nutrition 76A diets with or without GLAD (25 + 50 + 50 + 500 ppm) for 14 weeks. Dietary GLAD caused no signs of toxicity based on organ pathology and liver enzyme profiles. GLAD feeding strongly inhibited (80-83%, P < .0001) total intestinal tumor multiplicity and size in APC(Min/+) mice (means ± SEM tumors for control vs GLAD were 67.1 ± 5.4 vs. 11.3 ± 1.1 in males and 72.3 ± 8.9 vs 14.5 ± 2.8 in females). Mice fed GLAD had >95% fewer polyps with sizes of >2 mm compared with control mice and showed 75% and 85% inhibition of colonic tumors in males and females, respectively. Molecular analyses of polyps suggested that GLAD exerts efficacy by inhibiting cell proliferation, inducing apoptosis, decreasing β-catenin and caveolin-1 levels, increasing caspase-3 cleavage and p21, and modulating expression profile of inflammatory cytokines. These observations demonstrate that GLAD, a novel cocktail of chemopreventive agents at very low doses, suppresses intestinal tumorigenesis in APC(Min/+) mice with no toxicity. This novel strategy to prevent colorectal cancer is an important step in developing agents with high efficacy without unwanted side effects.