Cytoglobin may be involved in the healing process of gastric mucosal injuries in the late phase without angiogenesis

Insights into the function of cytoglobin

Since its discovery in 2001, the function of cytoglobin has remained elusive. Through extensive in vitro and in vivo research, a range of potential physiological and pathological mechanisms has emerged for this multifunctional member of the hemoglobin family. Currently, over 200 research publications have examined different aspects of cytoglobin structure, redox chemistry and potential roles in cell signalling pathways. This research is wide ranging, but common themes have emerged throughout the research. This review examines the current structural, biochemical and in vivo knowledge of cytoglobin published over the past two decades. Radical scavenging, nitric oxide homeostasis, lipid binding and oxidation and the role of an intramolecular disulfide bond on the redox chemistry are examined, together with aspects and roles for Cygb in cancer progression and liver fibrosis.

Taurine attenuated methotrexate-induced intestinal injury by regulating NF-κB/iNOS and Keap1/Nrf2/HO-1 signals

Methotrexate (MTX) is a well-known and widely used cytotoxic chemotherapeutic agent. However, intestinal mucosa damage is a serious adverse effect of MTX. Taurine (TUR) is a sulfur-containing free β-amino acid with antioxidant and therapeutic value against several diseases. The current study aimed to determine the protective effect of TUR against MTX-induced intestinal injury. Rats were allocated into four groups. The first group received vehicles only. The second group received TUR at a dose of 250 mg/kg i.p. For induction of intestinal injury, the rats in the third group were given MTX once at a dose of 20 mg/kg, i.p. The fourth group received TUR 7 days before and 7 days after MTX, as previously described. TUR significantly attenuated the cytokine release by suppressing NF-κB and iNOS expressions. Moreover, cotreatment with TUR attenuated the increased MDA level while it enhanced the antioxidant GSH and SOD levels mediated by effective downregulation of Keap1 expression, while the expression of Nrf2, HO-1, and cytoglobin were up-regulated. Additionally, TUR mitigated the apoptosis and proliferation indices by decreasing the elevated levels of intestinal PCNA and caspase-3. Finally, TUR potently increased the cytotoxic activity of MTX toward Caco-2, MCF-7, and A549 cancer cells. In conclusion, TUR was a promising agent for relieving MTX-mediated intestinal injury via various antioxidant, anti-inflammatory, and antiapoptotic mechanisms.

Effect of cytoglobin overexpression on extracellular matrix component synthesis in human tenon fibroblasts

BACKGROUND

Conjunctival filtering bleb scar formation is the main reason for the failure of glaucoma filtration surgery. Cytoglobin (Cygb) has been reported to play an important role in extracellular matrix (ECM) remodeling, fibrosis and tissue damage repairing. This study aimed to investigate the role of Cygb in anti-scarring during excessive conjunctival wound healing after glaucoma filtration surgery.

METHODS

Cygb was overexpressed in human tenon fibroblasts (hTFs) by transfecting hTFs with lentiviral particles encoding pLenti6.2-FLAG-Cygb. Changes in the mRNA and protein levels of fibronectin, collagen I, collagen III, TGF-β1, and HIF1α were determined by RT-PCR and western blotting respectively.

RESULTS

After Cygb overexpression, hTFs displayed no significant changes in visual appearance and cell counts compared to controls. Whereas, Cygb overexpression significantly decreased the mRNA and protein expression levels of collagen I, collagen III and fibronectin compared with control (p < 0.01). There was also a statistically significant decrease in the mRNA and protein levels of TGF-β1 and HIF-1α in hTFs with overexpressed Cygb compared with control group (p < 0.05).

CONCLUSION

Our study provided evidence that overexpression of Cygb decreased the expression levels of fibronectin, collagen I, collagen III, TGF-β1 and HIF-1α in hTFs. Therefore, therapies targeting Cygb expression in hTFs may pave a new way for clinicians to solve the problem of post-glaucoma surgery scarring.

Novel lymphoid enhancer-binding factor 1-cytoglobin axis promotes extravasation of osteosarcoma cells into the lungs

Lung metastasis is a major cause of mortality in patients with osteosarcoma (OS). A better understanding of the molecular mechanism of OS lung metastasis may facilitate development of new therapeutic strategies to prevent the metastasis. We have established high- and low-metastatic sublines (LM8-H and LM8-L, respectively) from Dunn OS cell line LM8 by using in vivo image-guided screening. Among the genes whose expression was significantly increased in LM8-H compared to LM8-L, the transcription factor lymphoid enhancer-binding factor 1 (LEF1) was identified as a factor that promotes LM8-H cell extravasation into the lungs. To identify downstream effectors of LEF1 that are involved in OS lung metastasis, 13 genes were selected based on LM8 microarray data and genomewide meta-analysis of a public database for OS patients. Among them, the cytoglobin (Cygb) gene was identified as a key effector in promoting OS extravasation into the lungs. CYGB overexpression increased the extravasation ability of LM8-L cells, whereas knocking out the Cygb gene in LM8-H cells reduced this ability. Our results showed a novel LEF1-CYGB axis in OS lung metastasis and may provide a new way of developing therapeutic strategies to prevent OS lung metastasis.

Cytoglobin in tumor hypoxia: novel insights into cancer suppression

Emerging new and intriguing roles of cytoglobin (Cygb) have attracted considerable attention of cancer researchers in recent years. Hypoxic upregulation of Cygb as well as its altered expression in various human cancers suggest another possible role of this newly discovered globin in tumor cell response under low oxygen tension. Since tumor hypoxia is strongly associated with malignant progression of disease and poor treatment response, it constitutes an area of paramount importance for rational design of cancer selective therapies. However, the mechanisms involved during this process are still elusive. This review outlines the current understanding of Cygb's involvement in tumor hypoxia and discusses its role in tumorigenesis. A better perception of Cygb in tumor hypoxia response is likely to open novel perspectives for future tumor therapy.

Gastroduodenal mucosal defense

PURPOSE OF REVIEW

To review recent developments in the field of gastroduodenal mucosal defense.

RECENT FINDINGS

Research in the field of gastroduodenal mucosal defense has focused on continued elucidation of molecular mechanisms that protect the mucosa and influence healing at the cellular level. Review of literature over the past year reveals focus on familiar processes such as superoxide dismutase, nitric oxide, heme oxygenase-1, neutrophil infiltration, cysteamine, mucin, hydrogen sulfide, ghrelin, adiponectin and the influence of Helicobacter pylori, but also brings into light new processes such as the balance between apoptosis and cellular proliferation, as well as the influence of other organ systems such as the bone marrow and central nervous system on the gastrointestinal tract.

SUMMARY

These new published findings contribute to our overall understanding of gastroduodenal defense and suggest innovative avenues of future research and possible novel therapeutic targets.