Blockage of Glyoxalase I Inhibits Colorectal Tumorigenesis and Tumor Growth via Upregulation of STAT1, p53, and Bax and Downregulation of c-Myc and Bcl-2

Development of pathway-oriented screening to identify compounds to control 2-methylglyoxal metabolism in tumor cells

Controlling tumor-specific alterations in metabolic pathways is a useful strategy for treating tumors. The glyoxalase pathway, which metabolizes the toxic electrophile 2-methylglyoxal (MG), is thought to contribute to tumor pathology. We developed a live cell-based high-throughput screening system that monitors the metabolism of MG to generate D-lactate by glyoxalase I and II (GLO1 and GLO2). It utilizes an extracellular coupled assay that uses D-lactate to generate NAD(P)H, which is detected by a selective fluorogenic probe designed to respond exclusively to extracellular NAD(P)H. This metabolic pathway-oriented screening is able to identify compounds that control MG metabolism in live cells, and we have discovered compounds that can directly or indirectly inhibit glyoxalase activities in small cell lung carcinoma cells.

Identification of HAGHL as a novel metabolic oncogene regulating human colorectal cancer progression

PURPOSE

Cancer development remains the most challenging obstacle in colorectal cancer (CRC) treatment. The current study aims to identify and demonstrate novel oncogenes for CRC.

METHODS

The CRC data of the Cancer Genome Atlas database and the Gene Expression Omnibus database were subjected to bioinformatics analysis to identify the novel potential diagnostic and prognostic biomarkers for CRC. Immunohistochemical assay, western blot, and quantitative PCR (qPCR) were used to analyze hydroxyacylglutathione hydrolase-like (HAGHL) gene expression in CRC tissues and cultured CRC cells. D-Lactate colorimetric assay was applied to determine concentration of D-lactate in supernatants from CRC tissues and cell culture medium. Cell counting kit-8 (CCK-8) assay, flow cytometry, tumor xenografts experiment, and TUNEL staining analysis were performed to evaluate the function of HAGHL in CRC.

RESULTS

We comprehensively analyzed the CRC data of the Cancer Genome Atlas database and the Gene Expression Omnibus database, and identified several novel potential diagnostic and prognostic biomarkers for CRC, including HAGHL, DNTTIP1, DHX34, and AP1S3. The expression of HAGHL, the strongest oncogenic activity gene, is positively related to D-lactate levels in CRC tissues and negatively associated with patient prognosis. HAGHL downregulation suppressed the production of D-lactate and induced apoptosis, resulting in inhibition of cell proliferation in vitro. In vivo experiment showed that knockdown of HAGHL induced cell apoptosis and inhibited tumor growth.

CONCLUSION

These findings suggest that HAGHL acts as a novel metabolic oncogene and demonstrate the underlying mechanism by which HAGHL regulates CRC progression, highlighting its utility as a diagnostic and prognostic factor and as a potential therapeutic target for the treatment of CRC.

Assessment of the Anticancer Potentials of the Free and Metal-Organic Framework (UiO-66) - Delivered Phycocyanobilin

Phycocyanin (C-PC) is a constitutive chromoprotein of Arthrospira platensis, which exhibits promising efficacy against different types of cancer. In this study, we cleaved C-PC's chromophore phycocyanobilin (PCB) and demonstrated its ability as an anti-cancer drug for Colorectal cancer (CRC). PCB displayed an anti-cancer effect for CRC (HT-29) cells with IC50 of 108 µg/ml. Assessing the transcripts levels of some biomarkers revealed that the PCB caused an upregulation in the anti-metastatic gene NME1 level and downregulation of the COX-2 level. The flow cytometric results showed the effect of PCB on the arrest of the cell cycle's G1 phase. In addition, we successfully synthesized the UiO-66 (Zr-MOF). We incorporated the PCB into UiO-66 nanoparticles with a loading percentage of 46 %. Assessment of the cytotoxic effects of UiO-66@PCB showed a 2-fold improvement in the IC50 compared to the free PCB. In conclusion, we have shown that PCB displayed a promising potential as an anti-cancer agent. Yet, it is considered a safe and natural substance that can help to mitigate cancer spread and symptoms. In the meantime, UiO-66 can be used as a safe nano-delivery tool for PCB.

Glyoxalase 1 as a Therapeutic Target in Cancer and Cancer Stem Cells

Methylglyoxal (MG) is a dicarbonyl compound formed in cells mainly by the spontaneous degradation of the triose phosphate intermediates of glycolysis. MG is a powerful precursor of advanced glycation end products, which lead to strong dicarbonyl and oxidative stress. Although divergent functions of MG have been observed depending on its concentration, MG is considered to be a potential anti-tumor factor due to its cytotoxic effects within the oncologic domain. MG detoxification is carried out by the glyoxalase system. Glyoxalase 1 (Glo1), the ubiquitous glutathione-dependent enzyme responsible for MG degradation, is considered to be a tumor promoting factor due to it catalyzing the removal of cytotoxic MG. Indeed, various cancer types exhibit increased expression and activity of Glo1 that closely correlate with tumor cell growth and metastasis. Furthermore, mounting evidence suggests that Glo1 contributes to cancer stem cell survival. In this review, we discuss the role of Glo1 in the malignant progression of cancer and its possible use as a promising therapeutic target for tumor therapy. We also summarize therapeutic outcomes of Glo1 inhibitors as prospective treatments for the prevention of cancer.

Glyoxalase 1 knockdown induces age-related β-cell dysfunction and glucose intolerance in mice

Tight control of glycemia is a major treatment goal for type 2 diabetes mellitus (T2DM). Clinical studies indicated that factors other than poor glycemic control may be important in fostering T2DM progression. Increased levels of methylglyoxal (MGO) associate with complications development, but its role in the early steps of T2DM pathogenesis has not been defined. Here, we show that MGO accumulation induces an age-dependent impairment of glucose tolerance and glucose-stimulated insulin secretion in mice knockdown for glyoxalase 1 (Glo1KD). This metabolic alteration associates with the presence of insular inflammatory infiltration (F4/80-positive staining), the islet expression of senescence markers, and higher levels of cytokines (MCP-1 and TNF-α), part of the senescence-activated secretory profile, in the pancreas from 10-month-old Glo1KD mice, compared with their WT littermates. In vitro exposure of INS832/13 β-cells to MGO confirms its casual role on β-cell dysfunction, which can be reverted by senolytic treatment. These data indicate that MGO is capable to induce early phenotypes typical of T2D progression, paving the way for novel prevention approaches to T2DM.

Methylglyoxal Levels in Human Colorectal Precancer and Cancer: Analysis of Tumor and Peritumor Tissue

Colorectal cancer (CRC) is one of the most common cancers worldwide and its incidence is increasing; therefore, an understanding of its oncogenic mechanisms is critical for improving its treatment and management. Methylglyoxal (MGO) has a highly reactive aldehyde group and has been suggested to play a role in oncogenesis. However, no standardized data are currently available on MGO levels in colorectal precancerous and cancerous lesions. We collected 40 matched colorectal tumor and peritumor tissues from patients with low-grade dysplasia (LGD), high-grade dysplasia (HGD), and invasive cancer (IC). MGO levels increased between LGD, HGD, and IC tumor tissues (215.25 ± 39.69, 267.45 ± 100.61, and 587.36 ± 123.19 μg/g protein, respectively; p = 0.014). The MGO levels in peritumor tissue increased and were significantly higher than MGO levels in tumor tissue (197.99 ± 49.40, 738.09 ± 247.87, 933.41 ± 164.83 μg/g protein, respectively; p = 0.002). Tumor tissue MGO levels did not correlate with age, sex, underlying disease, or smoking status. These results suggest that MGO levels fluctuate in progression of CRC and warrants further research into its underlying mechanisms and function in tumor biology.

The Dual-Role of Methylglyoxal in Tumor Progression - Novel Therapeutic Approaches

One of the hallmarks of cancer cells is their metabolic reprogramming, which includes the preference for the use of anaerobic glycolysis to produce energy, even in presence of normal oxygen levels. This phenomenon, known as “Warburg effect”, leads to the increased production of reactive intermediates. Among these Methylglyoxal (MGO), a reactive dicarbonyl known as the major precursor of the advanced glycated end products (AGEs), is attracting great attention. It has been well established that endogenous MGO levels are increased in several types of cancer, however the MGO contribution in tumor progression is still debated. Although an anti-cancer role was initially attributed to MGO due to its cytotoxicity, emerging evidence has highlighted its pro-tumorigenic role in several types of cancer. These apparently conflicting results are explained by the hormetic potential of MGO, in which lower doses of MGO are able to establish an adaptive response in cancer cells while higher doses cause cellular apoptosis. Therefore, the extent of MGO accumulation and the tumor context are crucial to establish MGO contribution to cancer progression. Several therapeutic approaches have been proposed and are currently under investigation to inhibit the pro-tumorigenic action of MGO. In this review, we provide an overview of the early and latest evidence regarding the role of MGO in cancer, in order to define its contribution in tumor progression, and the therapeutic strategies aimed to counteract the tumor growth.

Fra-1 Inhibits Cell Growth and the Warburg Effect in Cervical Cancer Cells via STAT1 Regulation of the p53 Signaling Pathway

The oncogenesis of cervical cancer is a multi-factor and multi-step process, and major risk factors include oncogene activation with tumor suppressor gene inactivation, viral factors, and immune factors. For example, the human papillomavirus (HPV) has been linked to the occurrence of cervical cancer. At present, the pathogenesis of cervical cancer remains unclear. Fra-1 (Fos-related antigen 1, also known as FOSL1) is a member of the Fos family and an important nuclear transcription factor that regulates normal cell growth, differentiation, and apoptosis. In the present study, we found that Fra-1 inhibited the proliferation of cervical cancer cells while also promoting apoptosis and affecting cell cycle distribution. Moreover, Fra-1 up-regulated STAT1 expression and modulated p53 signal pathway activity in cervical cancer cells. Overexpression of Fra-1 inhibited cell senescence by altering sirtuin 1 (SIRT1) expression in HeLa cells, and Fra-1 overexpression restored mitochondrial disorder and suppressed metabolic reprogramming in HeLa cells. Silencing of STAT1 impaired the inhibitory effect of Fra-1 on cervical cancer cell growth, while knock-down of STAT1 reversed the effect on cell senescence and mitochondrial dysfunction caused by Fra-1 in HeLa cells. Silencing of STAT1 also recovered metabolic reprogramming in cervical cancer cells. In summary, our results show that Fra-1 inhibited cervical cancer cell growth and the Warburg effect via STAT1-mediated regulation of the p53 signaling pathway.

Transmembrane and Ubiquitin-Like Domain Containing 1 Protein (TMUB1) Negatively Regulates Hepatocellular Carcinoma Proliferation via Regulating Signal Transducer and Activator of Transcription 1 (STAT1)

Background

Hepatocellular carcinoma (HCC) is a common malignancy, but the pathogenesis of HCC is unclear. TMUB1 has an inhibitory effect on normal hepatocytes, but its role in HCC has not been reported.

Material/Methods

We used immunohistochemistry to observe the expression of transmembrane and ubiquitin-like domain containing 1 protein (TMUB1) and signal transducer and activator of transcription 1 (STAT1) in 132 HCC tissue specimens. The expression of TMUB1, STAT1, and CCND1 in HCC cells were detected by quantitative polymerase chain reaction (qPCR) and western blotting. Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2′-deoxyuridine (EdU) assays were used for detecting HCC cells proliferation, and Transwell assays were used for observing the invasion and migration of HCC cells.

Results

TMUB1 was negatively correlated with HCC pathological malignancy; low expression of TMUB1 indicated poor prognosis. TMUB1 inhibited proliferation but not metastasis in HCC cells. TMUB1 expression was positively correlated with STAT1 in 132 HCC tissues, TMUB1 promoted the expression of STAT1, and suppressed the expression of CCND1 in HCC cells.

Conclusions

TMUB1 negatively regulates hepatocellular carcinoma proliferation via regulating STAT1.

Reactive metabolite production is a targetable liability of glycolytic metabolism in lung cancer

Increased glucose uptake and metabolism is a prominent phenotype of most cancers, but efforts to clinically target this metabolic alteration have been challenging. Here, we present evidence that lactoylglutathione (LGSH), a byproduct of methylglyoxal detoxification, is elevated in both human and murine non-small cell lung cancers (NSCLC). Methylglyoxal is a reactive metabolite byproduct of glycolysis that reacts non-enzymatically with nucleophiles in cells, including basic amino acids, and reduces cellular fitness. Detoxification of methylglyoxal requires reduced glutathione (GSH), which accumulates to high levels in NSCLC relative to normal lung. Ablation of the methylglyoxal detoxification enzyme glyoxalase I (Glo1) potentiates methylglyoxal sensitivity and reduces tumor growth in mice, arguing that targeting pathways involved in detoxification of reactive metabolites is an approach to exploit the consequences of increased glucose metabolism in cancer.

TPX2 silencing exerts anti‑tumor effects on hepatocellular carcinoma by regulating the PI3K/AKT signaling pathway

Hepatocellular carcinoma (HCC) is one of the primary causes of cancer-associated deaths worldwide. Current treatment methods include surgical resection, chemotherapy and radiotherapy; however the curative rate remains low, thus novel treatments are required. The aim of the present study was to investigate the role of targeting protein for Xenopus kinesin-like protein 2 (TPX2) in the growth of HCC and its underlying molecular mechanism. Immunohistochemistry staining, reverse transcription-quantitative (RT-q)PCR and western blotting were used to detect the expression of TPX2 mRNA and protein in liver cancer tissue samples, adjacent normal liver tissue samples, and the HCC cell lines Huh7, Hep3B, PLC/PRF/5 and MHCC97-H. The recombinant plasmid pMagic4.1-shRNA-TPX2 was constructed and transfected into Huh7 and Hep3B HCC cells to silence TPX2 expression. The proliferation, apoptosis, migration and invasion of Huh7 cells and Hep3B cells were evaluated before and after TPX2 silencing. The mRNA and protein expression levels of multiple signaling pathway-associated genes were detected by RT-qPCR and western blotting. The expression levels of TPX2 mRNA and protein were significantly higher in HCC tissue samples compared with adjacent normal liver tissue sample. TPX2 mRNA and protein expression levels were detected in the different HCC cell lines. The recombinant plasmid pMagic4.1-shRNA-TPX2 was successfully transfected into Huh7 and Hep3B cells, resulting in TPX2 silencing. TPX2 knockdown significantly reduced cell proliferation, cell migration and cell invasion of Huh7 and Hep3B cells, whilst also increasing the rate of apoptosis in these cells. Following TPX2 silencing, the expression levels of PI3K, phospho-AKT, Bcl-2, c-Myc and Cyclin D1 were significantly decreased, whereas the expression levels of P21 and P27 were significantly increased. In conclusion, TPX2 may suppress the growth of HCC by regulating the PI3K/AKT signaling pathway and thus, TPX2 may be a potential target for the treatment of liver cancer.

Liraglutide Treatment Ameliorates Neurotoxicity Induced by Stable Silencing of Pin1

Post-translational modulation of peptidylprolyl isomerase Pin1 might link impaired glucose metabolism and neurodegeneration, being Pin1 effectors target for the glucagon-Like-Peptide1 analog liraglutide. We tested the hypotheses in Pin1 silenced cells (SH-SY5Y) treated with 2-deoxy-d-glucose (2DG) and methylglyoxal (MG), stressors causing altered glucose trafficking, glucotoxicity and protein glycation. Rescue by liraglutide was investigated. Pin1 silencing caused increased levels of reactive oxygen species, upregulated energy metabolism as suggested by raised levels of total ATP content and mRNA of SIRT1, PGC1α, NRF1; enhanced mitochondrial fission events as supported by raised protein expression of FIS1 and DRP1. 2DG and MG reduced significantly cell viability in all the cell lines. In Pin1 KD clones, 2DG exacerbated altered mitochondrial dynamics causing higher rate of fission events. Liraglutide influenced insulin signaling pathway (GSK3b/Akt); improved cell viability also in cells treated with 2DG; but it did not revert mitochondrial dysfunction in Pin1 KD model. In cells treated with MG, liraglutide enhanced cell viability, reduced ROS levels and cell death (AnnexinV/PI); and trended to reduce anti-apoptotic signals (BAX, BCL2, CASP3). Pin1 silencing mimics neuronal metabolic impairment of patients with impaired glucose metabolism and neurodegeneration. Liraglutide rescues to some extent cellular dysfunctions induced by Pin1 silencing.

Role of MYC-miR-29-B7-H3 in Medulloblastoma Growth and Angiogenesis

Medulloblastoma (MB) is the most common embryonal neuroepithelial tumor, with poor patient outcomes and secondary complications. In this study, we investigated the role of the B7 family of immune checkpoint homolog 3 (B7-H3) expression in MB angiogenesis. B7-H3, a co-inhibitory immune checkpoint, is highly expressed and is associated with lower overall survival in MYC⁺ MB's. Evidence for a direct transcriptional role of MYC on the B7-H3 gene promoter was confirmed by MYC inhibition and anti-MYC antibody ChIP analysis. Interestingly, MYC inhibition not only downregulated the B7-H3 protein expression, but also rescued miR-29 expression, thus indicating a triangular regulatory relationship between MYC, miR-29, and B7-H3 in Group 3 MB cells. From RNA seq and IPAD assay, we observed a negative feedback loop between miR-29 and MYC that may control B7-H3 expression levels in MB cells. Our studies show that B7-H3 expression levels play a crucial role in promoting MB angiogenesis which can be inhibited by miR-29 overexpression via miR-29-mediated B7-H3 downregulation. The tumor suppressor role of miR-29 is mediated by the activation of JAK/STAT1 signaling that further plays a role in MYC-B7-H3 downregulation in MB. This study highlights B7-H3 as a viable target in MB angiogenesis, and that the expression of miR-29 can inhibit B7-H3 and sensitize MB cells to treatment with MYC-inhibiting drugs.

Syringic acid triggers reactive oxygen species–mediated cytotoxicity in HepG2 cells

Hepatocellular carcinoma is the second most common cause of cancer death in the world and its incidence has dramatically increased worldwide in the past two decades. Syringic acid (SA) has been studied for its hepatoprotective, anti-inflammatory, immunomodulatory, free radical scavenging, and antioxidant activities. We aimed to evaluate the cytotoxic effect of SA against human hepatoma HepG2 cell line. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. HepG2 cells were treated with SA at concentration ranges of 25, 50, and 100 µM for 24 h. Reactive oxygen species (ROS) expression was investigated by dichlorofluorescein staining assay. Morphological changes of SA-treated HepG2 cells were evaluated by acridine orange (AO) and ethidium bromide (EB) dual staining. Apoptotic marker gene expressions were evaluated by qPCR. SA treatment caused significant cytotoxicity and liberation of ROS in HepG2 cells. AO and EB staining showed membrane blebbing and distortion in SA-treated cells. Apoptotic markers such as caspases 3 and 9, cytochrome c, Apaf-1, Bax, and p53 gene expressions were significantly increased upon SA treatment indicating the possibility of apoptosis induction in HepG2 cells. This treatment also caused significant downregulation of Bcl-2 gene expression. SA has a cytotoxic effect on human HepG2 cell line, and this might be a promising agent in anticancer research.

Long Noncoding RNAs in Colorectal Adenocarcinoma; an in silico Analysis

Long noncoding RNAs (lncRNAs) are lengthy noncoding transcripts which are involved in critical signaling pathways including cell cycle and apoptosis so it is not surprising to see their altered expression in human tumors. Colorectal adenocarcinoma is one the most frequent malignancies worldwide. The role of lncRNAs in colorectal adenocarcinoma is not well understood. To study the significance of lncRNAs in colorectal adenocarcinoma, we retrieved 189 approved lncRNAs from HGNC. The genes were imported into the cBioPortal database for transcriptomic analyses. We queried all the samples from TCGA provisional colorectal adenocarcinoma with RNA-seq v2 data in our study and considered RNA dysregulation with Z-score: ±2. The lncRNA which was altered in most of the patients were considered as "significant lncRNA" for further analyses. We considered the association of candidate lncRNAs with clinicopathologic parameters of samples including tumor disease anatomic site, neoplasm histologic types, tumor stage and survival. We also compute the specificity of the significant lncRNAs expression in colorectal adenocarcinoma comparing with other human cancers in cancer portal. Our analysis showed that lncRNAs SNHG6, PVT1 and ZFAS1 allocated the maximum alteration among the colorectal cases. The expression of SNHG6 and ZFAS1 was more in rectal adenocarcinoma than the colon carcinoma while the PVT1 showed the same expression levels in both tissues. However, we found that upregulation of PVT1 has been reduced the overall survival in patients. Altogether these data showed SNHG6, PVT1 and ZFAS1, are promising candidates for experimental research on colorectal adenocarcinoma to discover novel biomarker for this prevalent cancer.

Cancer/testis Antigen MAGEA3 Interacts with STAT1 and Remodels the Tumor Microenvironment

Cancer-testis antigen MAGEA3, being restrictedly expressed in testis and various kinds of tumors, has long been considered as an ideal target for immunotherapy. In this study, we report that MAGEA3 interacts with STAT1 and regulates the expression of tyrosine phosphorylated STAT1 (pY-STAT1) in tumor cells. We show that pY-STAT1 is significantly up-regulated when MAGEA3 is silenced by MAGEA3-specific siRNA. RNA sequencing analysis identified 274 STAT1-related genes to be significantly altered in expression level in MAGEA3 knockdown cells. Further analysis of these differentially expressed genes with GO enrichment and KEGG pathway revealed that they are mainly enriched in plasma membrane, extracellular region and MHC class I protein complex, and involved in the interferon signaling pathways, immune response, antigen presentation and cell chemotaxis. The differentially expressed genes associated with chemokines, antigen presentation and vasculogenic mimicry formation were validated by biological experiments. Matrigel matrix-based tube formation assay showed that silencing MAGEA3 in tumor cells impairs tumor vasculogenic mimicry formation. These data indicate that MAGEA3 expression in tumor cells is associated with immune cells infiltration into tumor microenvironment and anti-tumor immune responses, implying that it may play an important role in tumor immune escape. Our findings reveal the potential impact of MAGEA3 on the immunosuppressive tumor microenvironment and will provide promising strategies for improving the efficacy of MAGEA3-targeted immunotherapy.