The Functions of EphA1 Receptor Tyrosine Kinase in Several Tumors.

BACKGROUND: Eph receptors tyrosine kinase (RTK) were identified in 1987 from hepatocellular carcinoma cell lines and were the largest known subfamily of RTK. Eph receptors can be divided into two categories, EphA and EphB, based on their structure and receptor-ligand specificity. EphA can be divided into 10 species (EphA 1-10) and EphB into 6 species (EphB1-6). Similarly, the ligands of Eph receptors are Ephrins. Ephrins also can be divided into Ephrin A and Ephrin B, of which there are five species(Ephrin-A1-5) and three species(Ephrin-B1-3). Among the Eph receptors, EphA1 has been the least studied so far. As far as we know, Eph receptors are involved in multiple pathologies, including cancer progression, tumor angiogenesis, intestinal environmental stability, the lymph node system, neurological disease, and inhibition of nerve regeneration after injury. There is a link between EphA1, integrin and ECM- related signal pathways. Ephrin-A1 is a ligand of the EphA1 receptor. EphA1 and ephrin-A1 functions are related to tumor angiogenesis. EphA1 and ephrin-A1 also play roles in gynecological diseases. Ephrin-A1 and EphA1 receptors regulate the follicular formation, ovulation, embryo transport, implantation and placental formation, which are of great significance for the occurrence of gynecological tumor diseases. EphA1 has been identified as an oncoprotein in various tumors and has been associated with the prognosis of various tumors in recent years. EphA1 is considered a driver gene in tumor genomics. There are significant differences in EphA1 expression levels in different types of normal tissues and tumors and even in different stages of tumor development, suggesting its functional diversity. Changes at the gene level in cell biology are often used as biological indicators of cancer, known as biomarkers, which can be used to provide diagnostic or prognostic information and are valuable for improving the detection, monitoring and treatment of tumors. However, few prognostic markers can selectively predict clinically significant tumors with poor prognosis. These malignancies are more likely to progress and lead to death, requiring more aggressive treatment. Currently available treatments for advanced cancer are often ineffective, and treatment options are mainly palliative. Therefore, early identification and treatment of those at risk of developing malignant tumors are crucial. Although pieces of evidence have shown the role of EphA1 in tumorigenesis and development, its specific mechanism is still unknown to a great extent. OBJECTIVE: This review reveals the changes and roles of EphA1 in many tumors and cancers. The change of EphA1 expression can be used as a biological marker of cancer, which is valuable for improving tumor detection, monitoring and treatment and can be applied to imaging. Studies have shown that structural modification of EphA1 could make it an effective new drug. EphA1 is unique in that it can be considered a prognostic marker in many tumors and is of important meaning for clinical diagnosis and operative treatment. At the same time, the study of the specific mechanism of EphA1 in tumors can provide a new way for targeted therapy. METHODS: Relevant studies were retrieved and collected through the PubMed system. After determining EphA1 as the research object, by analyzing research articles on EphA1 in the PubMed system in recent 10 years, we found that EphA1 was closely connected with the occurrence and development of tumors and further determined the references according to the influencing factors for review and analysis. RESULTS: EphA1 has been identified as a cancer protein in various tumors, such as hepatocellular carcinoma, nasopharyngeal carcinoma, ovarian cancer, gastric cancer, colorectal cancer, clear cell renal cell carcinoma, esophageal squamous cell carcinoma, breast cancer, prostate cancer and uveal melanoma. EphA1 is abnormally expressed in these tumor cells, which mainly plays a role in cancer progression, tumor angiogenesis, intestinal environmental stability, the lymph node system, nervous system diseases and gynecological diseases. In a narrow sense, EphA1 is especially effective in breast cancer in terms of gynecological diseases. However, the specific mechanism of EphA1 leading to the change of cancer cells in some tumors is not clear, which needs further research and exploration. CONCLUSION: RTK EphA1 can be used as a biomarker for tumor diagnosis (especially a prognostic marker), an indispensable therapeutic target for new anti-tumor therapies, and a novel anti-tumor drug.

Antimutagenic Effects of Selenium-Enriched Polysaccharides from Pyracantha fortuneana through Suppression of Cytochrome P450 1A Subfamily in the Mouse Liver.

Both selenium (Se) and polysaccharides from Pyracantha fortuneana (Maxim.) Li (PFPs) (P. fortuneana) have been reported to possess antioxidative and immuno-protective activities. Whether or not Se-containing polysaccharides (Se-PFPs) have synergistic effect of Se and polysaccharides on enhancing the antioxidant and immune activities remains to be determined. We previously reported that polysaccharides isolated from Se-enriched P. fortuneana (Se-PFPs) possessed hepatoprotective effects. However, it is not clear whether or not they have anti-mutagenic effects. In the present study, we compared and evaluated anti-mutagenic effects of Se-PFPs at three concentrations (1.35, 2.7 and 5.4 g/kg body weight) with those of PFPs, Se alone or Se + PFPs in mice using micronucleus assay in bone marrow and peripheral blood as well as mitomycin C-induced chromosomal aberrations in mouse testicular cells. We also elucidated the underlying mechanism. Our results demonstrated that Se-PFPs inhibited cyclophosphamide (CP)-induced micronucleus formation in both bone marrow and peripheral blood, enhanced the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in mouse liver, and reduced the activity and expression of cytochrome P450 1A (CYP4501A) in mouse liver in a dose-dependent manner. In addition, we found that the anti-mutagenic potential of Se-PFPs was higher than those of PFPs, Se alone or Se + PFPs at the same level. These results suggest that the anti-mutagenic potential of Se-PFPs may be mediated through the inhibition of the activity and expression of CYP4501A. This study indicates that application of Se-PFPs may provide an alternative strategy for cancer therapy by targeting CYP1A family.

Inhibition on the growth of human MDA-MB-231 breast cancer cells in vitro and tumor growth in a mouse xenograft model by Se-containing polysaccharides from Pyracantha fortuneana.

Breast cancer is the second cause of cancer-related death among Women. Current therapies for breast cancer have adverse side-effects. Selenium (Se)-containing polysaccharides have multiple health benefits to humans. Pyracantha fortuneana (P. fortuneana) contains rich Se polysaccharides. We hypothesized that Se-containing polysaccharides from P. fortuneana possess anticancer activity on breast cancer via inhibiting growth and inducing apoptosis. This study aimed to assess the anticancer effect of Se-containing polysaccharides from P. fortuneana and the underlying mechanisms. Se-containing polysaccharides were purified. Their properties and monosaccharide compositions were analyzed. Their effects on cell growth, expression of cycle proteins, apoptosis and apoptosis-related protein, and tumor growth in mouse xenograft model were examined. This extract contained 93.7% (w/w) of carbohydrate, 2.1% (w/w) of uronic acid and 3.7µg/g of Se, and was considered as Se-conjugated polysaccharides (Se-PFPs). In vitro studies showed that treatment of triple negative breast cancer (TNBC) MDA-MB-231 cells with Se-PFPs (1) inhibited cell growth dose-dependently by arresting cells at G2 phase via inhibiting CDC25C-CyclinB1/CDC2 pathway; (2) caused apoptosis associated with increased p53, Bax, Puma and Noxa, decreased Bcl2, increased Bax/Bcl2 ratio and increased activities of caspases 3/9, suggesting its effect on p53-mediated cytochrome c-caspase pathway. Treatment of nude mice bearing MDA-MB-231-derived xenograft tumors with Se-PFPs significantly reduced tumor growth without altering body weight, confirming its antitumor activity without toxic side effects. Se-PFPs enhanced doxorubicin cytotoxic effects. It is concluded that Se-containing polysaccharides from P. fortuneana potently inhibit the growth and induce apoptosis of TNBC cells and can be potential anticancer agent for TNBC.

Combination of selenium-enriched green tea polysaccharides and Huo-ji polysaccharides synergistically enhances antioxidant and immune activity in mice.

BACKGROUND: The aim of this study was to investigate the influence of a combination of selenium-enriched green tea polysaccharides (Se-GTP) and Huo-ji polysaccharides (HJP) on the immune function and antioxidant activity in mice. RESULTS: The results showed that the indices of spleen and thymus were markedly increased, and the activity of natural killer (NK) cell was promoted in mice treated with the combination of Se-GTP and HJP. The combined treatment of Se-GTP and HJP also reduced the content of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in splenocytes. In addition, the activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were remarkably enhanced, and malondialdehyde (MDA) levels were significantly reduced in mice treated with combination of Se-GTP and HJP. Furthermore, the combined treatment of Se-GTP and HJP increased nuclear factor erythroid 2-related factor (Nrf2) expression at mRNA and protein levels in splenocytes. The effects of the combination treatment of Se-GTP and HJP in mice were stronger than with Se-GTP or HJP treatment alone. CONCLUSION: Our study suggests that the combined administration of Se-GTP and HJP can synergistically improve immune function and decrease the oxidative stress by enhancing the mechanisms involved in the clearance of free radicals.

Effects of polysaccharides from selenium-enriched Pyracantha fortuneana on mice liver injury.

We have previously reported that polysaccharides extracted from Pyracantha fortuneana (Maxim.) Li (P. fortuneana) lowered the oxidative stress and inhibited the inflammatory responses in mice. Our present study aims to determine the effects of Selenium enriched P. fortuneana polysaccharides (Se-PFPs) against carbon tetrachloride (CCl4)-induced liver injury in a mouse model. Our results displayed that CCl4 remarkably elevated the levels of alanine transferase (ALT), aspartate transaminase (AST), lactic dehydrogenase (LDH), cholesterol, triglycerides in serum. However, similar to BP treatment, supplementation of mice with Se-PFPs resulted in reversal of ALT, AST, LDH, cholesterol, triglycerides in serum. Contrary to CCl4, supplementation of mice with Se-PFPs elevated the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and levels of glutathione (GSH) in liver. Furthermore, Se-PFPs treatment increased the expression of GPx and catalase (CAT) at mRNA and protein levels in liver which were decreased in CCl4 group. Contrary to CCl4, Se-PFPs supplement decreased the levels of thiobarbituric acid reactive substances (TBAR) and H2O2, which served as lipid peroxidation biomarker. Our study indicates that Se-PFPs administration is effective in attenuating CCl4-induced liver injury. The mechanism underlying this effect may be attributed to the reduction of oxidative stress and inflammation in the liver by Se-PFPs through up-regulation of the antioxidant system. Our study suggests that Se-PFPs might be a potential dietary agent in the prevention of hepatic damage.

The importance of Loop 7 for the activity of calcineurin.

Calcineurin (CN) is a heterodimer composed of a catalytic subunit (CNA) and a regulatory subunit (CNB). Loop 7 lies within the CNA catalytic domain. To investigate the role of Loop 7 in enzyme activity, we systematically examined all its residues by site-directed deletion mutation. Our results show that the Loop 7 residues are important for enzyme activity. Besides deleting residues V314, Y315 or N316, enzyme activity also increased dramatically when residues D313 or K318 were deleted. In contrast, almost all activity was lost when L312 or N317 were deleted. Ni2+ and Mn2+ were effective activators for all active mutants. However, whereas the wild-type enzyme was more efficiently activated by Ni2+ than by Mn2+ with 32P-labeled R(II) peptide as substrate, the reverse was true in all the mutants. We also found that the effect of Loop 7 on enzyme activity was substrate dependent, and involved interactions between Loop 7 residues and the unresolved part of the CN crystal structure near the auto-inhibitory domain and catalytic site.