Impact of LKB1 status on radiation outcome in patients with stage III non-small-cell lung cancer

Preclinical studies suggest that loss of LKB1 expression renders cancer cells less responsive to radiation partly through NRF2-mediated upregulation of antioxidant enzymes protecting against radiation-induced DNA damage. Here we investigated the association of an alteration in this pathway with radio-resistance in lung cancer patients. Patients with locally advanced non-small cell lung cancer (LA-NSCLC) who were treated with chemoradiotherapy (CRT) and analyzed for LKB1 expression using semiquantitative immunohistochemistry. Clinical characteristics and expression of LKB1 were analyzed for association with radiotherapy outcomes. We analyzed 74 available tumor specimens from 178 patients. After a median follow-up of 40.7 months, 2-year cumulative incidence of locoregional recurrence (LRR) in patients who had LKB1Low expression was significantly higher than those with LKB1High expression (68.8% vs. 31.3%, P = 0.0001). LKB1Low expression was found significantly associated with a higher incidence of distant metastases (DM) (P = 0.0008), shorter disease-free survival (DFS) (P = 0.006), and worse overall survival (OS) (P = 0.02) compared to LKB1High expression. Moreover, patients with LKB1Low expression showed a significantly higher 2-year cumulative incidence of LRR (77.6% vs. 21%; P = 0.02), higher DM recurrence (P = 0.002), and shorter OS (P < 0.0001) compared with the EGFR-mutant group. For all patients with LKB1Low who had LRR, these recurrences occurred within the field of radiation, in contrast to those with LKB1High expression having both in-field, marginal, and out-of-field failures. LKB1 expression may serve as a potential biomarker for poor outcomes after receiving radiation in LA-NSCLC patients. Further studies to confirm the association and application are warranted.

Astaxanthin inhibits oxidative stress and apoptosis in diabetic retinopathy

BACKGROUND

The pathophysiology of diabetic retinopathy (DR) is thought to be influenced by oxidative stress. Astaxanthin (ASX) is a natural product with antioxidant effect, but it is not clear whether its mechanism of inhibiting the development of DR is related to anti-oxidation.

METHODS

Rats were intraperitoneally injected with streptozotocin (60 mg/kg) to create DR rat models followed by ASX (20 mg/kg) for 45 days. Retinal tissue was examined by Hematoxylin and Eosin staining. By using Enzyme-linked immunosorbent assay (ELISA), 2,7-Dichlorodrhydrofluorescein diace (DCFH-DA) probes, immunohistochemistry and western blot, it was feasible to evaluate the contents of inflammation-related factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 and macrophage inhibitory cytokine-1 (MIC-1)), oxidative stress-related indicators (glutathione (GSH), malonic dialdehyde (MDA), glutathione peroxidase (GPx), reactive oxygen species (ROS) and Total antioxidant capacity (T-AOC)), antioxidant enzymes (hemoxgenase-1(HO-1) and Quinone Oxidoreductase 1 (NQO1)), and apoptosis-related proteins (Bcl-2, Bcl2 Associated X Protein (BAX), and cleaved-caspase-3). Additionally, antioxidant proteins downstream of the nuclear factor E2 related factors (Nrf-2) pathway, expression levels of Nrf2/ Kelch-like ECH-associated protein 1(Keap 1) pathway-associated proteins, and nuclear and cytoplasmic levels of Nrf2 were assessed using immunohistochemistry, western blot, or quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

ASX alleviated retinal tissue damage by increasing overall retina thickness and ganglion cell layer (GCL) cell numbers and exerted the anti-inflammatory, anti-oxidative stress, and anti-apoptosis effects in DR rats. Additionally, ASX could inhibit the expression of Keap1, promote the transport of Nrf2 from cytoplasm to nucleus and facilitate the expressions of HO-1, NQO1, γ-glutamylcysteine synthetase, (γ-GCS) and GPx.

CONCLUSION

ASX exerted antioxidant effects through Nrf2/keap1 pathway, thereby alleviating apoptosis, inflammation, and oxidative stress in retinal tissues of DR rats.

Beta-Boswellic Acid Protects Against Cerebral Ischemia/Reperfusion Injury via the Protein Kinase C Epsilon/Nuclear Factor Erythroid 2-like 2/Heme Oxygenase-1 Pathway

Ischemic strokes are associated with a high rate of disability and death globally. Cerebral ischemia/reperfusion (I/R) injury is a type of brain damage associated with oxidative stress after an ischemic stroke. Beta-boswellic acid (β-BA) reportedly exerts antioxidant and neuroprotective effects, but its role in cerebral I/R injury is unclear. The aim of this research was to investigate the neuroprotective effects, as well as the mechanisms of β-BA in cerebral I/R injury. In vivo experiments were conducted using a rat middle cerebral artery occlusion and reperfusion (MCAO/R) model, and in vitro experiments were performed using a rat neuronal oxygen-glucose deprivation and reoxygenation (OGD/R) model. Triphenyltetrazolium chloride staining, neurological function scores, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, hematoxylin and eosin staining, and antioxidant levels in the brain were used to assess the effects of β-BA. Flow cytometry was used to detect reactive oxygen species and apoptotic cells. Western blotting and immunofluorescence staining were used to measure protein levels. The results showed that β-BA markedly improved neurological deficits and decreased infarct volume and necrotic neurons in rats. The in vitro results showed that β-BA protected neurons against OGD/R-induced injury. Additionally, β-BA significantly increased the phosphorylation of protein kinase C epsilon (PRKCE) at S729, the translocation of nuclear factor erythroid 2-like 2 (NFE2L2), and expression of heme oxygenase-1 (HMOX1). This study demonstrates that β-BA exerts neuroprotective effects against cerebral I/R via the activation of the PRKCE/NFE2L2/HMOX1 pathway and is a potential therapeutic candidate for ischemic stroke.

Omentin-1 protects renal function of mice with type 2 diabetic nephropathy via regulating miR-27a-Nrf2/Keap1 axis

Omentin-1, a novel identified adipokine, always significantly decreases in patients with metabolic syndrome. However, the functional roles of omentin-1 in diabetic nephropathy (DN) remains largely unknown. In the present study, we found that omentin-1 treatment could improve renal function of type 2 diabetic db/db mice. ELISA assay and immunohistochemistry staining showed that omentin-1 reduced the productions of proinflammatory cytokines (IFN-γ, TNF-α, MCP-1 and IL-8), and improved oxidative stress level (CAT, MDA and SOD) in the kidney tissue, indicating omentin-1 could relieved the inflammatory response and suppressed oxidative stress. Mechanistic analysis demonstrated that omentin-1 down-regulated miR-27a expression, and subsequently inhibited oxidative stress and inflammation. Luciferase reporter assay and western blot further revealed that miR-27a directly targeted the 3' untranslated region (UTR) of nuclear factor erythroid 2-like 2 (Nrf2) and reduced its expression in type 2 DN. Taken together, these findings provide a new function of omentin-1 in renal protection and also delineate multiple potential targets for therapeutic intervention for type 2 DN.

Dual NRF2 paralogs in Coho salmon and their antioxidant response element targets

The transcription factor NFE2L2 (Nuclear Factor, Erythroid 2-Like 2, or NRF2) plays a key role in maintaining the redox state within cells. Characterization of this pathway has extended to fish, most notably zebrafish (Danio rerio), in which two paralogs of the transcription factor exist: Nrf2a, an activator, and Nrf2b, a negative regulator during embryogenesis. Only one ARE target has been thoroughly delineated in zebrafish, and this deviated from the canonical sequence derived from studies in mammals. In general, the mechanistic pathway has not been characterized in non-model aquatic organisms that are commonly exposed to environmental pollutants. The current study compares the zebrafish paralogs to those found in a non-model teleost, the ecologically important salmonid, Oncorhnychus kisutch (coho salmon). Two salmon paralogs, Nrf2A and -2B, described here were found to possess only slightly greater identity between one another (84% of amino acids) than to the singleton ortholog of the esocid Esox lucius (80–82%), the nearest non-salmonid outgroup. Unlike one of the zebrafish forms, each is a strong activating factor based on sequence homology and in vitro testing. To uncover functional target AREs in coho, promoter flanking sequences were isolated for five genes that protect cells against oxidative stress: heme oxygenase 1, peroxiredoxin 1, glutamate-cysteine ligase, and the glutathione S-transferases pi and rho (hmox1, prdx1, gclc, gstp, and gstr). All except gstr had functional elements and all fit the standard mammalian-derived canonical sequence, unlike the motif found in zebrafish gstp. Expression studies demonstrate the presence of both Nrf2 paralogs in multiple organs, although in differing ratios. Collectively, our findings extend the conservation of Nrf2 and the ARE to salmonids, and should help inform future work in teleosts on mechanisms of redox control, as well as responsiveness of this pathway and its downstream antioxidant gene targets to chemical exposures in the environment.

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Salmon possess dual paralogs of Nrf2 (Nfe2l2).

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The paralogs are disproportionately expressed among tissues.

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Antioxidant response elements in salmon follow canonical mammalian motifs.