Unconjugated Bilirubin Is a Novel Prognostic Biomarker for Nasopharyngeal Carcinoma and Inhibits Its Metastasis via Antioxidation Activity

Indirect bilirubin impairs invasion of osteosarcoma cells via inhibiting the PI3K/AKT/MMP-2 signaling pathway by suppressing intracellular ROS

Background

Osteosarcoma is most prevalently found primary malignant bone tumors, with primary metastatic patients accounting for approximately 25% of all osteosarcoma patients, yet their 5-year OS remains below 30%. Bilirubin plays a key role in oxidative stress-associated events, including malignancies, making the regulation of its serum levels a potential anti-tumor strategy. Herein, we investigated the association of osteosarcoma prognosis with serum levels of TBIL, IBIL and DBIL, and further explored the mechanisms by which bilirubin affects tumor invasion and migration.

Methods

ROC curve was plotted to assess survival conditions based on the determined optimal cut-off values and the AUC. Then, Kaplan-Meier curves, along with Cox proportional hazards model, was applied for survival analysis. Inhibitory function of IBIL on the malignant properties of osteosarcoma cells was examined using the qRT-PCR, transwell assays, western blotting, and flow cytometry.

Results

We found that, versus osteosarcoma patients with pre-operative higher IBIL (>8.9 μmol/L), those with low IBIL (≤8.9 μmol/L) had shorter OS and PFS. As indicated by the Cox proportional hazards model, pre-operative IBIL functioned as an independent prognostic factor for OS and PFS in total and gender-stratified osteosarcoma patients (P < 0.05 for all). In vitro experiments further confirmed that IBIL inhibits PI3K/AKT phosphorylation and downregulates MMP-2 expression via reducing intracellular ROS, thereby decreasing the invasion of osteosarcoma cells.

Conclusions

IBIL may serve as an independent prognostic predictor for osteosarcoma patients. IBIL impairs invasion of osteosarcoma cells through repressing the PI3K/AKT/MMP-2 pathway by suppressing intracellular ROS, thus inhibiting its metastatic potential.

The Protective Role of the Heme Catabolic Pathway in Hepatic Disorders

Significance: As the central metabolic organ, the liver is exposed to a variety of potentially cytotoxic, proinflammatory, profibrotic, and carcinogenic stimuli. To protect the organism from these deleterious effects, the liver has evolved a number of defense systems, which include antioxidant substrates and enzymes, anti-inflammatory tools, enzymatic biotransformation systems, and metabolic pathways. Recent Advances: One of the pivotal systems that evolved during phylogenesis was the heme catabolic pathway. Comprising the important enzymes heme oxygenase and biliverdin reductase, this complex pathway has a number of key functions including enzymatic activities, but also cell signaling, and DNA transcription. It further generates two important bile pigments, biliverdin and bilirubin, as well as the gaseous molecule carbon monoxide. These heme degradation products have potent antioxidant, immunosuppressive, and cytoprotective effects. Recent data suggest that the pathway participates in the regulation of metabolic and hormonal processes implicated in the pathogenesis of hepatic and other diseases. Critical Issues: This review discusses the impact of the heme catabolic pathway on major liver diseases, with particular focus on the involvement of cellular targeting and signaling in the pathogenesis of these conditions. Future Directions: To utilize the biological consequences of the heme catabolic pathway, several unique therapeutic strategies have been developed. Research indicates that pharmaceutical, nutraceutical, and lifestyle modifications positively affect the pathway, delivering potentially long-term clinical benefits. However, further well-designed studies are needed to confirm the clinical benefits of these approaches. Antioxid. Redox Signal. 35, 734-752.

The prognostic value of serum bilirubin in colorectal cancer patients with surgical resection

PURPOSE

Serum bilirubin plays an important role in antioxidant and anticancer processes. The inverse association between serum bilirubin and cancer risk have been widely reported in multiple cancers. The aim of this retrospective study was to investigate the prognostic impact of serum bilirubin in colorectal cancer patients undergoing surgical resection.

METHODS

The value of serum bilirubin including total bilirubin, direct bilirubin, and indirect bilirubin were tested at pre-operatively in 330 colorectal cancer patients. The optimal cut-off values for these three biomarkers were determined by X-tile program. The relationship between serum bilirubin and outcomes were examined using Kaplan-Meier curves log-rank test, univariate and multivariate cox regression. Moreover, a number of risk factors were used to form a nomogram for evaluating risk of survival.

RESULTS

The optimal cut-off points of serum total bilirubin, direct bilirubin, and indirect bilirubin were 19.5 μmol/L, 5.0 μmol/L and 8.1 μmol/L, respectively. Elevated total bilirubin and direct bilirubin were significantly associated with overall survival in surgical colorectal cancer patients. Additionally, predictive nomogram including total bilirubin and direct bilirubin for overall survival was established for predicting overall survival in surgical colorectal cancer patients.

CONCLUSIONS

These findings indicated that preoperative elevated total bilirubin and direct bilirubin could be considered as independent prognostic biomarkers for poor overall survival of colorectal cancer patients.

Bilirubin Nanomedicines for the Treatment of Reactive Oxygen Species (ROS)-Mediated Diseases

Reactive oxygen species (ROS) are chemically reactive species that are produced in cellular aerobic metabolism. They mainly include superoxide anion, hydrogen peroxide, hydroxyl radicals, singlet oxygen, ozone, and nitric oxide and are implicated in many physiological and pathological processes. Bilirubin, a cardinal pigment in the bile, has been increasingly investigated to treat cancer, diabetes, ischemia-reperfusion injury, asthma, and inflammatory bowel diseases (IBD). Indeed, bilirubin has been shown to eliminate ROS production, so it is now considered as a promising therapeutic agent for ROS-mediated diseases and can be used for the development of antioxidative nanomedicines. This review summarizes the current knowledge of the physiological mechanisms of ROS production and its role in pathological changes and focuses on discussing the antioxidative effects of bilirubin and its application in the experimental studies of nanomedicines. Previous studies have shown that bilirubin was mainly used as a responsive molecule in the microenvironment of ROS overproduction in neoplastic tissues for the development of anticancer nanodrugs; however, it could also exert powerful ROS scavenging activity in chronic inflammation and ischemia-reperfusion injury. Therefore, bilirubin, as an inartificial ROS scavenger, is expected to be used for the development of nanomedicines against more diseases due to the universality of ROS involvement in human pathological conditions.

Bilirubin Attenuates ER Stress-Mediated Inflammation, Escalates Apoptosis and Reduces Proliferation in the LS174T Colonic Epithelial Cell Line

Mildly elevated serum unconjugated bilirubin (UCB) concentrations are associated with protection against disease conditions underpinned by cellular and metabolic stress. To determine the potential therapeutic efficacy of UCB we tested it in an in vitro model of gut inflammation. Tunicamycin TUN (10 µg/mL) was used to induce endoplasmic reticular stress (ERS) affecting N-glycosylation in LS174T cells. Cultured cells were investigated with addition of UCB at doses 0.1, 1 and 10µM (resulting in bilirubin:albumin ratios of 0.325-0.003)against ER stress-mediated effects including inflammation, cell survival (determined by apoptosis) and proliferation. Gene expression of ER stress markers (Grp78, Perk, XBP1 and ATF6) were evaluated in addition to cytokine concentrations in media after six hours of treatment. We then verified the potential role of UCB in executing programmed cell death via PARP, Caspase3 and Annexin V assays and further explored cell proliferation using the Click-iT EdU assay. A dose of 10µM UCB most potently reduced tunicamycin-mediated effects on enhanced UPR markers, inflammatory cytokines and proliferation; however all the doses (i.e.0.1-10µM) reduced the expression of ER stress and inflammatory markers Grp78, NLRP3, IL1-b, XBP1, PERK and ATF6. Furthermore, media concentrations of pro-inflammatory cytokines IL-8, IL-4 and TNFα decreased and the anti-inflammatory cytokine IL-10 increased (P<0.05). A dose of 10µM UCB initiated intrinsic apoptosis via Caspase 3 and in addition reduced cellular proliferation. Collectively, these data indicate that co treatment with UCB resulted in reducing ER stress response to TUN in gastrointestinal epithelial cells, reduced the subsequent inflammatory response, induced cancer cell death and decreased cellular proliferation. These data suggest that mildly elevated circulating or enteric UCB might protect against gastrointestinal inflammatory disorders.

Prognostic value of serum bilirubin in southern Chinese patients with advanced nasopharyngeal carcinoma

BACKGROUND

We evaluated the prognostic value of serum bilirubin in advanced nasopharyngeal carcinoma (NPC) patients.

METHODS

Seven-hundred fifty-nine advanced NPC patients treated with definitive chemoradiotherapy were retrospectively analyzed. Serum indirect bilirubin (IBIL) and direct bilirubin (DBIL) were measured before treatment. To evaluate different cutoff points for serum bilirubin, we utilized ROC curves. The Kaplan-Meier method and log-rank test were adopted to calculate and compare survival outcomes. Cox proportional hazard models were used to perform univariate and multivariate analyses.

RESULTS

At 5 y, IBIL >7.15 μmol/l were significantly associated with superior progression-free survival (PFS, 83.6% vs 70.3%; P < .001), overall survival (OS, 88.6% vs 80.5%; P = .012), distant metastasis-free survival (DMFS, 90.3% vs 82.8%; P = .006), and locoregional relapse-free survival (LRFS, 92.1% vs 86.4%; P = .048) than IBIL ≤7.15 μmol/l. Similarly, patients with DBIL >2.65 μmol/l had better prognosis across all outcomes than those of patients with DBIL ≤2.65 μmol/l (all P < .05), except no difference was observed in LRFS (90.5% vs. 87.3%, P = .195). Multivariate analyses showed that IBIL >7.15 μmol/l was an independent protective prognostic factor for PFS (HR, 0.57; 95% CI, 0.40-0.81; P = .002), OS (HR, 0.67; 95% CI, 0.43-0.92; P = .041), and DMFS (HR, 0.63; 95% CI, 0.40-0.98; P = .034); while serum DBIL only remained significant for PFS (HR, 0.63; 95% CI, 0.44-0.89; P = .009).

CONCLUSIONS

Pretreatment IBIL and DBIL are potentially independent prognostic factors for patients with advanced NPC.

The prognostic impact of serum bilirubin in stage IV colorectal cancer patients

BACKGROUND

Bilirubin played a great role in antioxidation and anticancer and has been considered as a promising prognostic factor of non-liver disease-related death in various cancers. The aim of this study was to assess the prognostic value of pre-treatment serum bilirubin in stage IV CRC patients.

METHODS

Serum bilirubin including TBIL, DBIL, and IBI which were tested at pre-treatment were investigated in 154 stage IV CRC patients in Zhongda Hospital, Nanjing, China, from July 2005 to July 2011. X-tile program was used to determine the optimal cut-off values of these three biomarkers. Kaplan-Meier analysis, univariate, and multivariate cox regression as well as time-dependent ROC curve analysis were performed to evaluate the relations between serum bilirubin and survival outcomes.

RESULTS

We got the results that the optimal cut-off points of serum TBIL, DBIL, and IBI levels were 12.9, 6.1, and 4.8 μmol/L, respectively. Univariate analysis showed that elevated TBIL, DBIL, and CEA were significantly associated with poor 5-year OS in stage IV CRC patients. Multivariate cox analysis indicated that the high DBIL (HR=1.603, 95%CI=1.053-2.442, P<.028) and CEA (HR=1.785, 95%CI=1.123-2.837, P=.014) could be identified as independent factors for poor OS. Furthermore, time-dependent ROC curves demonstrated that high DBIL had similar prognostic efficacy as elevated CEA for poor OS (AUC=0.63 and 0.61, respectively).

CONCLUSIONS

Pre-treatment elevated TBIL and DBIL levels were associated with poor OS in stage IV CRC patients. Moreover, DBIL could be considered as an independent prognostic biomarker for OS. Furthermore, DBIL had similar prognostic efficacy as CEA for OS.

Cyclooxygenase-2 expression is positively associated with lymph node metastasis in nasopharyngeal carcinoma

BACKGROUND

Accumulating evidence has demonstrated that cyclooxygenase-2 (COX-2) is involved in head and neck cancers, especially in nasopharyngeal carcinoma (NPC). However, the association between COX-2 expression and lymph node metastasis in NPC remains uncertain. This systematic review and meta-analysis meta-analysis investigated the relationship between COX-2 expression and lymph node metastasis and other signs of disease progression in NPC.

METHODS

Previously published studies assessing COX-2 expression and lymph node metastasis in NPC were identified in four English databases and three Chinese ones (Pubmed, Embase, Cochrane Database of Systematic Reviews, Web of Science, China National Knowledge Infrastructure, Wanfang, Vip Journal Integration Platform) up to November 2016. Quality of all eligible studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). Pooled odds ratios (OR) and their 95% confidence intervals (95%CI) were calculated with fixed-effects or random-effects model to evaluate the effects of COX-2 expression on lymph node metastasis.

RESULTS

A total of 27 studies with 1797 NPC patients met the inclusion criteria. The expression of COX-2 was significantly higher in patients with nasopharyngeal carcinoma than those without the carcinoma, with a combined OR of 21.17 (95%CI = 15.02-29.85, I2 = 35.1%, Pheterogeneity = 0.070). A statistically significant association between COX-2 expression and lymph node metastasis in NPC patients, with an OR of 4.44 (95%CI = 3.46-5.70, I2 = 38.3%, Pheterogeneity = 0.024), and with other indicators of disease progression. Subgroup analyses based on COX-2 assay and staging criteria of TNM showed no significant heterogeneity.

CONCLUSIONS

The results suggest that expression of COX-2 is associated with lymph node metastasis and disease progression in NPC, indicating a potential role in evaluation of prognosis and in treatment decisions. COX-2 inhibitors have potential in the treatment of NPC that should be further investigated.