Sirtuin5 protects colorectal cancer from DNA damage by keeping nucleotide availability.

In our previous study, we reported that sirtuin5 (SIRT5), a member of the NAD+-dependent class III histone deacetylase family, is highly expressed in colorectal cancer (CRC). Herein we show that SIRT5 knockdown impairs the production of ribose-5-phosphate, which is essential for nucleotide synthesis, resulting in continuous and irreparable DNA damage and consequently leading to cell cycle arrest and enhanced apoptosis in CRC cells. These SIRT5 silencing-induced effects can be reversed by nucleoside supplementation. Mechanistically, SIRT5 activates transketolase (TKT), a key enzyme in the non-oxidative pentose phosphate pathway, in a demalonylation-dependent manner. Furthermore, TKT is essential for SIRT5-induced malignant phenotypes of CRC both in vivo and in vitro. Altogether, SIRT5 silencing induces DNA damage in CRC via post-translational modifications and inhibits tumor growth, suggesting that SIRT5 can serve as a promising target for CRC treatment.

Retracted: Resistin-Like Molecule Beta (RELM-ß) Regulates Proliferation of Human Diabetic Nephropathy Mesangial Cells via Mitogen-Activated Protein Kinases (MAPK) Signaling Pathway.

This publication has been retracted by the Editor due to the identification of non-original figure images and manuscript content that raise concerns regarding the credibility and originality of the study and the manuscript. Reference: Yun-Qian Wang, Cong-Cong Fan, Bao-Ping Chen, Jun Shi. Resistin-Like Molecule Beta (RELM-ß) Regulates Proliferation of Human Diabetic Nephropathy Mesangial Cells via Mitogen-Activated Protein Kinases (MAPK) Signaling Pathway. Med Sci Monit 2017; 23:3897-3903. DOI: 10.12659/MSM.905381.

Enterotoxigenic Bacteroides fragilis induces the stemness in colorectal cancer via upregulating histone demethylase JMJD2B.

The enrichment of Enterotoxigenic Bacteroides fragilis (ETBF) has been identified in CRC patients and associated with worse prognosis. Cancer stem cells (CSCs) play essential roles in CRC development. However, whether ETBF is involved in CSCs regulation is unknown. To clarify the role of ETBF in CSCs properties, we performed extreme limited dilution assays (ELDA) in nude mice injected with ETBF-treated or untreated CRC cells subcutaneously, tumor organoids culture in azoxymethane (AOM) mouse model after gavaging with or without ETBF, and cell sphere formation assay after incubating CRC cell lines with or without ETBF. The results indicated that ETBF increased the stemness of CRC cells in vivo and in vitro. Furthermore, ETBF enhanced the expression of core stemness transcription factors Nanog homeobox (NANOG) and sex determining region Y-box 2 (SOX2). Histone H3 Lysine 9 trimethylation (H3K9me3) is critical in regulating CSCs properties. As an epigenetic and transcriptional regulator, JmjC-domain containing histone demethylase 2B (JMJD2B) is essential for embryonic stem cell (ESC) transformation and H3K9me3 demethylation. Mechanistically, ETBF infection significantly upregulated JMJD2B levels in CRC cell lines and nude mice xenograft model. JMJD2B epigenetically upregulated NANOG expression via demethylating its promoter H3K9me3, to mediate ETBF-induced stemness of CRC cells. Subsequently, we found that the Toll-like receptor 4 (TLR4) pathway, activated by ETBF, contributed to the enhanced expression of JMJD2B via nuclear transcription factor nuclear factor of activated T cells 5 (NFAT5). Finally, in human CRC samples, the amount of ETBF positively correlated with nuclear NFAT5, JMJD2B, and NANOG expression levels. In summary, ETBF upregulated JMJD2B levels in a TLR4-NFAT5-dependent pathway, and played an important role in stemness regulation, which promoted colorectal carcinogenesis.

JMJD2B-induced amino acid alterations enhance the survival of colorectal cancer cells under glucose-deprivation via autophagy.

Rationale: Post-translational modifications have emerged as vital players in alterations to tumor metabolism, including amino acid metabolic reprogramming. Jumonji domain-containing protein 2B (JMJD2B) enhances colorectal cancer (CRC) cell survival upon glucose deficiency. In the present study, we hypothesized that JMJD2B affects tumor cell amino acid metabolism in CRC and consequently promotes survival of CRC cells upon glucose deprivation. Methods: Non-target metabolic profiling was used to evaluate the roles of JMJD2B in CRC cell metabolism under glucose starvation. The roles of amino acid alterations induced by JMJD2B on CRC cell survival were determined by cell viability, immunoblotting, and clonogenic assays, and flow cytometry. The underlying mechanisms by which JMJD2B affected CRC cell metabolism were assessed using immunofluorescence staining, chromatin immunoprecipitation assays, electron microscopy in CRC cell lines, and using xenograft models. The correlation between JMJD2B and LC3B expression in human CRC specimens was assessed using immunohistochemistry. Results: Profound metabolic reprogramming was detected in JMJD2B knockdown CRC cells under glucose deficiency, especially those involving amino acid metabolites. Silencing of JMJD2B reduced the levels of certain amino acids that were induced by glucose deficiency. Among these amino acids, asparagine (Asn), phenylalanine (Phe), and histidine (His) promoted CRC cell survival under glucose starvation when JMJD2B was knocked down. Mechanistically, downregulation of JMJD2B inhibited autophagy in CRC cells through epigenetic regulation of microtubule associated protein 1 light chain 3 beta (LC3B), and subsequently decreased intracellular amino acid (Asn, Phe, His) levels under glucose deprivation, thus suppressing the survival of CRC cells. Using a nude mouse xenograft model, we verified that inhibiting JMJD2B could decrease the levels of amino acids (Asn, Phe, His). In addition, the inhibitory effects of JMJD2B-knockdown on tumor growth and amino acids level were rescued by overexpression of LC3B. Furthermore, we observed that the high expression of LC3B was more likely detected in tissuses with high expression of JMJD2B (P < 0.001) in 60 human CRC tissues. Conclusion: These results indicated that JMJD2B sustained the intracellular amino acids derived from autophagy in CRC cells upon glucose deficiency, partly through epigenetic regulation of LC3B, thus driving the malignancy of CRC.

Sirtuin5 contributes to colorectal carcinogenesis by enhancing glutaminolysis in a deglutarylation-dependent manner.

Reversible post-translational modifications represent a mechanism to control tumor metabolism. Here we show that mitochondrial Sirtuin5 (SIRT5), which mediates lysine desuccinylation, deglutarylation, and demalonylation, plays a role in colorectal cancer (CRC) glutamine metabolic rewiring. Metabolic profiling identifies that deletion of SIRT5 causes a marked decrease in 13C-glutamine incorporation into tricarboxylic-acid (TCA) cycle intermediates and glutamine-derived non-essential amino acids. This reduces the building blocks required for rapid growth. Mechanistically, the direct interaction between SIRT5 and glutamate dehydrogenase 1 (GLUD1) causes deglutarylation and functional activation of GLUD1, a critical regulator of cellular glutaminolysis. Consistently, GLUD1 knockdown diminishes SIRT5-induced proliferation, both in vivo and in vitro. Clinically, overexpression of SIRT5 is significantly correlated with poor prognosis in CRC. Thus, SIRT5 supports the anaplerotic entry of glutamine into the TCA cycle in malignant phenotypes of CRC via activating GLUD1.

Resistin-Like Molecule Beta (RELM-ß) Regulates Proliferation of Human Diabetic Nephropathy Mesangial Cells via Mitogen-Activated Protein Kinases (MAPK) Signaling Pathway.

BACKGROUND Resistin-like molecule beta (RELM-ß) has been reported to be associated with diabetic nephropathy (DN). However, the role of RELM-ß in DN is poorly understood. This study was conducted to delineate the underlying mechanisms of action and to investigate the role of RELM-ß in the primitive development of DN via MAPK signaling pathways. MATERIAL AND METHODS Lentivirus-mediated vectors and RNAi technology were used to establish the model of RELM-ß up-regulated and down-regulated expression in human mesangial cells (HMCs). The proliferation of HMCs was detected through CCK-8 method. The cell cycle and cell proliferation of HMCs was detected through flow cytometry. The MAPKs pathway protein activity was detected through Western blotting. RESULTS The HMCs with up-regulated and down-regulated expression of RELM-ß increased or decreased significantly at 2-3 days. The HMCs with high glucose intervention reversed the proliferation inhibition. The HMCs with exogenous glucose or RELM-ß protein intervention partially reversed the cell cycle inhibition. Among the MAPKs pathway, the phosphorylation activity of p38MAPK and JNK increased or decreased and ERK1/2 did not change in the overexpression or inhibition of RELM-ß. The p38 MAPK pathway inhibitor SB202190 significantly inhibited the proliferation of HMCs caused by overexpression of RELM-ß. Up-regulated expression of RELM-b induced the phosphorylation of p38 MAPK, JNK in HMCs and promoted HMCs proliferation and participated in early DN through the MAPKs pathway. CONCLUSIONS The results provide evidence that RELM-b is a potential molecular target for the treatment of DN.

Long Noncoding RNA CCAT2 as a Potential Novel Biomarker to Predict the Clinical Outcome of Cancer Patients: A Meta-Analysis.

Background: Colon Cancer-Associated Transcript 2 (CCAT2) has been demonstrated associated with clinical outcomes in various tumors. However, the results from each study were unfortunately insufficient and not completely consistent. Therefore, we conduct a systematic meta-analysis to evaluate the value for a feasible biomarker for metastasis and prognosis. Methods: A meta-analysis was performed using data obtained through a systematic search of PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure, Wanfang database and VIP database. The pooled odds ratio (OR) and hazard ratio (HR) with 95% Confidence interval (CI ) using random-effect were used to identify the relationship of CCAT2 with clinical outcome of cancer patients. Subgroup analysis and sensitivity analysis were performed. Results: A total of 867 patients from eight studies were finally included. Patients with high CCAT2 expression underwent an increased risk of lymph node metastasis (LNM) (OR=3.09, 95% CI: 1.53-6.26) and distant metastasis (DM) (OR=7.70, 95% CI: 3.26-18.17). CCAT2 was also significantly correlated with overall survival (OS) (HR=2.19, 95%CI: 1.70-2.82) and progression-free survival (PFS) (HR=2.59, 95% CI: 1.78-3.76). Moderate heterogeneity was observed in meta-analysis for LNM. However, the results remained robust in multiple sensitivity analyses. Conclusions: High expression of CCAT2 was linked with poor clinical outcome. CCAT2 can serve as a potential molecular marker for prognosis in different types of cancers.

[Pollution Status and Migration of Mercury in the Sediments of Nansi Lake in Shandong Province].

The content of mercury and fractions were determined, in order to discuss the pollution situation and migration ability of mercury in inflow rivers and surface sediments of Nansi Lake. The average content of mercury in the sediments of the Nansi Lake was 0.046 mg · kg(-1), significantly higher than the environmental background values, which showed that Nansi Lake suffered from mercury pollution. Mercury in sediments existed mainly in the residual fraction, accounting for 65. 15%. The proportion of non-residual fractions was relatively small, in the order of organic bound fraction (30.61%), extractable fraction (2.93%), and Fe/Mn oxide (1.31%). The spatial change of non-residual fractions was that Weishan Lake and Nanyang Lake had higher non-residual mercury content than Zhaoyang Lake and Dushan Lake, and the non-residual mercury had a certain potential ecological harm on Weishan Lake and Nanyang Lake. From the horizontal view, the mercury content in the surface sediments of Nansi Lake had visible difference and the pollution degree was different among sub-lakes, so horizontal migration of mercury was obvious. Vertically, the mercury content showed a trend of increasing from the bottom to the top in core sediments, which might be associated with social and economic conditions in different periods.

Silencing of JMJD2B induces cell apoptosis via mitochondria-mediated and death receptor-mediated pathway activation in colorectal cancer.

OBJECTIVE: To investigate the molecular mechanism of colorectal cancer (CRC) cell apoptosis induced by the Jumonji domain containing 2B (JMJD2B) silencing. METHODS: Both HCT116 and LoVo CRC cell lines were used for analyses. Cell apoptosis after JMJD2B silencing was determined by flow cytometry. JC-1 fluorescence probe was applied to measure the mitochondrial outer membrane permeabilization by flow cytometry and fluorescence microscopy. Immunofluorescence was used to detect cytochrome C translocation from mitochondria to cytosol after JMJD2B silencing. The efficacy of JMJD2B silencing on the protein levels of Bcl-2 family, caspase proteins, CCAAT/enhancer binding protein homologous protein (CHOP) and glucose-regulated protein 78 (GRP78) were detected by Western blot. RESULTS: JMJD2B silencing induced CRC cell apoptosis via a decrease of the anti-apoptotic gene Bcl-2 family expression, leading to the translocation of Bak and Bax proteins and the promotion of mitochondrial membrane disruption, resulting in the release of cytochrome C from mitochondria and subsequent caspase-9 and caspase-3 cleavage. It also increased the amount of cleaved caspase-8 involved in the death receptor-related apoptotic pathway. Bcl-2 homology 3 interacting-domain death agonist (Bid), a specific caspase-8 substrate involved in the Fas signaling pathway, subsequently induced cleavage via caspase-8 activation. However, levels of CHOP and GRP78 remained unchanged after JMJD2B silencing. CONCLUSIONS: JMJD2B silencing induced CRC cell apoptosis via both mitochondria-related and death receptor-related pathways. The cleavage of Bid activated by caspase-8 might serve as a crosstalk mediator between these two pathways in CRC.