A functional trinucleotide repeat polymorphism in the 5'-untranslated region of the glutathione biosynthetic gene GCLC is associated with increased risk for lung and aerodigestive tract cancers

Implications of GCLC in prognosis and immunity of lung adenocarcinoma and multi-omics regulation mechanisms

BACKGROUND

Ferroptosis is an iron-dependent type of regulated cell death, and has been implicated in lung adenocarcinoma (LUAD). Evidence has proved the key role of glutamate-cysteine ligase catalytic subunit (GCLC) in ferroptosis, but its role in LUAD remains unclear. Herein, we explored the implications of GCLC and relevant genes in LUAD prognosis and immunity as well as underlying molecular mechanisms.

METHODS

This work gathered mRNA, miRNA, DNA methylation, somatic mutation and copy-number variation data from TCGA-LUAD. WGCNA was utilized for selecting GCLC-relevant genes, and a GCLC-relevant prognostic signature was built by uni- and multivariate-cox regression analyses. Immune compositions were estimated via CIBERSORT, and two immunotherapy cohorts of solid tumors were analyzed. Multi-omics regulatory mechanisms were finally assessed.

RESULTS

Our results showed that GCLC was overexpressed in LUAD, and potentially resulted in undesirable survival. A prognostic model was generated, which owned accurate and independent performance in prognostication. GCLC, and relevant genes were notably connected with immune compositions and immune checkpoints. High GCLC expression was linked with better responses to anti-PD-L1 and anti-CTLA-4 treatment. Their possible DNA methylation sites were inferred, e.g., hypomethylation in cg19740353 might contribute to GCLC up-regulation. Frequent genetic mutations also affected their expression. Upstream transcription factors (E2F1/3/4, etc.), post-transcriptional regulation of miRNAs (hsa-mir-30c-1, etc.), lncRNAs (C8orf34-AS1, etc.), and IGF2BP1-mediated m6A modification were identified. It was also found NOP58-mediated SUMOylation post-translational modification.

CONCLUSIONS

Together, we show that GCLC and relevant genes exert crucial roles in LUAD prognosis and immunity, and their expression can be controlled by complex multi-omics mechanisms.

Differential gene expression identifies a transcriptional regulatory network involving ER-alpha and PITX1 in invasive epithelial ovarian cancer

Background

The heterogeneous subtypes and stages of epithelial ovarian cancer (EOC) differ in their biological features, invasiveness, and response to chemotherapy, but the transcriptional regulators causing their differences remain nebulous.

Methods

In this study, we compared high-grade serous ovarian cancers (HGSOCs) to low malignant potential or serous borderline tumors (SBTs). Our aim was to discover new regulatory factors causing distinct biological properties of HGSOCs and SBTs.

Results

In a discovery dataset, we identified 11 differentially expressed genes (DEGs) between SBTs and HGSOCs. Their expression correctly classified 95% of 267 validation samples. Two of the DEGs, TMEM30B and TSPAN1, were significantly associated with worse overall survival in patients with HGSOC. We also identified 17 DEGs that distinguished stage II vs. III HGSOC. In these two DEG promoter sets, we identified significant enrichment of predicted transcription factor binding sites, including those of RARA, FOXF1, BHLHE41, and PITX1. Using published ChIP-seq data acquired from multiple non-ovarian cell types, we showed additional regulatory factors, including AP2-gamma/TFAP2C, FOXA1, and BHLHE40, bound at the majority of DEG promoters. Several of the factors are known to cooperate with and predict the presence of nuclear hormone receptor estrogen receptor alpha (ER-alpha). We experimentally confirmed ER-alpha and PITX1 presence at the DEGs by performing ChIP-seq analysis using the ovarian cancer cell line PEO4. Finally, RNA-seq analysis identified recurrent gene fusion events in our EOC tumor set. Some of these fusions were significantly associated with survival in HGSOC patients; however, the fusion genes are not regulated by the transcription factors identified for the DEGs.

Conclusions

These data implicate an estrogen-responsive regulatory network in the differential gene expression between ovarian cancer subtypes and stages, which includes PITX1. Importantly, the transcription factors associated with our DEG promoters are known to form the MegaTrans complex in breast cancer. This is the first study to implicate the MegaTrans complex in contributing to the distinct biological trajectories of malignant and indolent ovarian cancer subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08276-8.

The role of polymorphisms in glutathione-related genes in asbestos-related diseases

BACKGROUND

The study investigated the influence of GCLC, GCLM, GSTM1, GSTT1 and GSTP1 polymorphisms, as well as the influence of interactions between polymorphism and interactions between polymorphisms and asbestos exposure, on the risk of developing pleural plaques, asbestosis and malignant mesothelioma (MM).

SUBJECTS AND METHODS

The cross sectional study included 940 asbestos-exposed subjects, among them 390 subjects with pleural plaques, 147 subjects with asbestosis, 225 subjects with MM and 178 subjects with no asbestos-related disease. GCLC rs17883901, GCLM rs41303970, GSTM1 null, GSTT1 null, GSTP1 rs1695 and GSTP1 rs1138272 genotypes were determined using PCR based methods. In statistical analysis, logistic regression was used.

RESULTS

GSTT1 null genotype was associated with the decreased risk for pleural plaques (OR = 0.63; 95% CI = 0.40-0.98; p = 0.026) and asbestosis (OR = 0.51; 95% CI = 0.28-0.93; p = 0.028), but not for MM. A positive association was found between GSTP1 rs1695 AG + GG vs. AA genotypes for MM when compared to pleural plaques (OR = 1.39; 95% CI = 1.00-1.94; p = 0.049). The interactions between different polymorphisms showed no significant influence on the risk of investigated asbestos-related diseases. The interaction between GSTT1 null polymorphism and asbestos exposure decreased the MM risk (OR = 0.17; 95% CI = 0.03-0.85; p = 0.031).

CONCLUSIONS

Our findings suggest that GSTT1 null genotype may be associated with a decreased risk for pleural plaques and asbestosis, may modify the association between asbestos exposure and MM and may consequently act protectively on MM risk. This study also revealed a protective effect of the interaction between GSTP1 rs1695 polymorphism and asbestos exposure on MM risk.

A ferroptosis-related gene signature predicts overall survival in patients with lung adenocarcinoma

Aims: To elucidate the association between ferroptosis-related genes and prognosis in patients with lung adenocarcinoma (LUAD). Materials & methods: A ferroptosis-related gene signature was made by lasso regression analysis through the LUAD datasets of the Cancer Genome Atlas. The prognostic value of the multigene signature was externally validated in the GSE72094 dataset from the Gene Expression Omnibus database. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis were used to explore underlying mechanisms. Results & conclusion: We established a novel ferroptosis-related gene signature for overall survival in LUAD that was predictive in both the training and validation cohorts. Immune-related pathways were significantly enriched, and immune status differed between the high- and low-risk groups. Targeting ferroptosis is a potential therapeutic option in LUAD. These results still need to be confirmed by more studies.

Polymorphisms in Neuronal Growth Regulator 1 and Otoancorin Alternate the Susceptibility to Lung Cancer in Chinese Nonsmoking Females

Cell adhesion molecules (CAMs) play crucial roles in the genesis and progress of tumor. We investigated the effects of single nucleotide polymorphisms (SNPs) of CAMs, neuronal growth regulator 1 (NEGR1), and Otoancorin (OTOA) on lung cancer susceptibility in Chinese nonsmoking females. Logistic regression and Cox regression analyses were conducted to investigate the effects of SNPs and environmental factors. For rs3102911, genotype TT carriers decreased the risk of lung cancer with an odds ratio (OR) of 0.635. AA genotypes of rs741718 increased the risk of lung cancer with an OR of 3.527. In stratified analysis, genotype AA carriers of rs741718 had a high susceptibility to lung adenocarcinoma compared with GG and AG genotypes. Analyses of association between SNPs and clinical characteristics revealed that rs3102911 as a protective factor and rs741718 as a risk factor influenced the lung cancer occurrence and progression in nonsmoking females.

An Integrated Approach for Preventing Oral Cavity and Oropharyngeal Cancers: Two Etiologies with Distinct and Shared Mechanisms of Carcinogenesis

Head and neck squamous cell carcinoma (HNSCC) was the 7th most common malignancy worldwide in 2018 and despite therapeutic advances, the overall survival rate for oral squamous cell carcinoma (OSCC; ∼50%) has remained unchanged for decades. The most common types are OSCC and oropharyngeal squamous cell carcinoma (OPSCC, survival rate ∼85%). Tobacco smoking is a major risk factor of HNSCC. In the developed world, the incidence of OSCC is declining as a result of tobacco cessation programs. However, OPSCC, which is also linked to human papillomavirus (HPV) infection, is on the rise and now ranks as the most common HPV-related cancer. The current state of knowledge indicates that HPV-associated disease differs substantially from other types of HNSCC and distinct biological differences between HPV-positive and HPV-negative HNSCC have been identified. Although risk factors have been extensively discussed in the literature, there are multiple clinically relevant questions that remain unanswered and even unexplored. Moreover, existing approaches (e.g., tobacco cessation, vaccination, and chemoprevention) to manage and control this disease remain a challenge. Thus, in this review, we discuss potential future basic research that can assist in a better understanding of disease pathogenesis which may lead to novel and more effective preventive strategies for OSCC and OPSCC.

Targeting Glutathione Metabolism: Partner in Crime in Anticancer Therapy

Glutathione (GSH) is the predominant low-molecular-weight antioxidant with a ubiquitous distribution inside the cell. The steady-state level of cellular GSH is dependent on the balance between synthesis, hydrolysis, recycling of glutathione disulphide (GSSG) as well as cellular extrusion of reduced, oxidized, or conjugated-forms. The augmented oxidative stress typical of cancer cells is accompanied by an increase of glutathione levels that confers them growth advantage and resistance to a number of chemotherapeutic agents. Targeting glutathione metabolism has been widely investigated for cancer treatment although GSH depletion as single therapeutic strategy has resulted largely ineffective if compared with combinatorial approaches. In this review, we circumstantiate the role of glutathione in tumour development and progression focusing on how interfering with different steps of glutathione metabolism can be exploited for therapeutic purposes. A dedicated section on synthetic lethal interactions with GSH modulators will highlight the promising option of harnessing glutathione metabolism for patient-directed therapy in cancer.

High GCLC level in tumor tissues is associated with poor prognosis of hepatocellular carcinoma after curative resection

Glutamate-cysteine ligase catalytic subunit (GCLC) has been reported to overexpress in a variety types of cancer and be related with tumor progression and drug resistance. However, little has been known about GCLC's prognostic significance and biological roles in hepatocellular carcinoma (HCC). In the present study, we evaluated GCLC expression level using immunohistochemical staining (IHC) in tissue microarray (TMA) containing paired tumor and peritumoral liver tissues from 168 patients with HCC who received curative resection. GCLC levels in tumor tissues were significantly higher than in peritumoral liver tissues, and tumor GCLC level was associated with overall survival (OS) and disease-free survival (DFS). Five-year OS and DFS rates were 41.15% and 25.88% for the group with high tumor GCLC level, compared with 68.09% and 47.51% for the group with low tumor GCLC level (P<0.001 and P=0.001, respectively). Moreover, quantitative reverse transcription PCR (qRT-PCR) analysis demonstrated that GCLC was transcriptionally activated in HCC tissues when comparing with peritumoral tissues. Tumor GCLC level, which correlated to tumor differentiation, microvascular invasion and BCLC stage, was independent prognostic factors for both OS (P=0.006) and DFS (P=0.003). Importantly, tumor GCLC level was still significantly associated with OS and DFS in patients with early HCC. GCLC-based nomogram models were further established and exhibit significantly higher predictive accuracy as compared with routine clinical staging systems. In conclusion, tumor GCLC is a potential prognostic biomarker for HCC patients after receiving curative resection.

Characterization of porcine simple sequence repeat variation on a population scale with genome resequencing data

Simple sequence repeats (SSRs) are used as polymorphic molecular markers in many species. They contribute very important functional variations in a range of complex traits; however, little is known about the variation of most SSRs in pig populations. Here, using genome resequencing data, we identified ~0.63 million polymorphic SSR loci from more than 100 individuals. Through intensive analysis of this dataset, we found that the SSR motif composition, motif length, total length of alleles and distribution of alleles all contribute to SSR variability. Furthermore, we found that CG-containing SSRs displayed significantly lower polymorphism and higher cross-species conservation. With a rigorous filter procedure, we provided a catalogue of 16,527 high-quality polymorphic SSRs, which displayed reliable results for the analysis of phylogenetic relationships and provided valuable summary statistics for 30 individuals equally selected from eight local Chinese pig breeds, six commercial lean pig breeds and Chinese wild boars. In addition, from the high-quality polymorphic SSR catalogue, we identified four loci with potential loss-of-function alleles. Overall, these analyses provide a valuable catalogue of polymorphic SSRs to the existing pig genetic variation database, and we believe this catalogue could be used for future genome-wide genetic analysis.

Formaldehyde Induces Rho-Associated Kinase Activity to Evoke Airway Hyperresponsiveness

Formaldehyde, a common indoor air pollutant, exacerbates asthma and synergizes with allergen to induce airway hyperresponsiveness (AHR) in animal models. The mechanisms mediating formaldehyde-induced AHR remain poorly understood. We posit that formaldehyde modulates agonist-induced contractile response of human airway smooth muscle (HASM) cells to elicit AHR. HASM cells were exposed to formaldehyde or vehicle and agonist-induced intracellular Ca²⁺ ([Ca²⁺]_i) and myosin light-chain phosphatase (MYPT1) phosphorylation were determined. Air-liquid interface-differentiated human bronchial epithelial (HBE) cells were exposed to formaldehyde or vehicle and cocultured with HASM cells. Agonist-induced [Ca²⁺]_i and MYPT1 phosphorylation were determined in the cocultured HASM cells. Precision-cut human lung slices were exposed to PBS or varying concentrations of formaldehyde, and then carbachol-induced airway narrowing was determined 24 hours after exposure. HASM cells were transfected with nontargeting or nuclear factor erythroid-derived 2, like 2 (Nrf-2)-targeting small interfering RNA and exposed to formaldehyde or vehicle, followed by determination of antioxidant response (quinone oxido-reductase 1 and thioredoxin 1) and basal and agonist-induced MYPT1 phosphorylation. Formaldehyde enhanced the basal Rho-kinase activity and MYPT1 phosphorylation with little effect on agonist-induced [Ca²⁺]_i in HASM cells. Formaldehyde induced Nrf-2-dependent antioxidant response in HASM cells, although the MYPT1 phosphorylation was independent of Nrf-2 induction. Although HBE cells exposed to formaldehyde had little effect on agonist-induced [Ca²⁺]_i or MYPT1 phosphorylation in cocultured HASM cells, formaldehyde enhanced carbachol-induced airway responsiveness in precision-cut human lung slices. In conclusion, formaldehyde induces phosphorylation of the regulatory subunit of MYPT1, independent of formaldehyde-induced Nrf-2 activation in HASM cells. The findings suggest that the Rho kinase-dependent Ca²⁺ sensitization pathway plays a role in formaldehyde-induced AHR.

Significance of Polymorphisms and Expression of Enzyme-Encoding Genes Related to Glutathione in Hematopoietic Cancers and Solid Tumors

Antioxidant compounds such as glutathione and its enzymes have become the focus of attention of medical sciences. Glutathione, a specific tripeptide, is involved in many intercellular processes. The glutathione concentration is determined by the number of GAG repeats in gamma-glutamylcysteine synthetase. GAG polymorphisms are associated with an increased risk of schizophrenia, berylliosis, diabetes, lung cancer, and nasopharyngeal tumors. Cancer cells with high glutathione concentration are resistant to chemotherapy treatment. The oxidized form of glutathione is formed by glutathione peroxidases (GPXs). The changes in activity of GPX1, GPX2, and GPX3 isoforms may be associated with the development of cancers, for example, prostate cancer or even colon cancer. Detoxification of glutathione conjugates is possible due to activity of glutathione S-transferases (GSTs). Polymorphisms in GSTM1, GSTP1, and GSTO1 enzymes increase the risk of developing breast cancer and hepatocellular carcinoma. Gamma-glutamyl transpeptidases (GGTs) are responsible for glutathione degradation. Increased activity of GGT correlates with adverse prognosis in patients with breast cancer. Studies on genes encoding glutathione enzymes are continued in order to determine the correlation between DNA polymorphisms in cancer patients.

Generation and sequencing of pulmonary carcinoid tumor cell lines

INTRODUCTION

Pulmonary carcinoid tumors account for approximately 5% of all lung malignancies in adults, and comprise 30% of all carcinoid tumors. There are limited reagents available to study these rare tumors, and consequently no major advances have been made for patient treatment. We report the generation and characterization of human pulmonary carcinoid tumor cell lines to study underlying biology, and to provide models for testing novel chemotherapeutic agents.

METHODS

Tissue was harvested from three patients with primary pulmonary typical carcinoid tumors undergoing surgical resection. The tumor was dissociated and plated onto dishes in culture media. The established cell lines were characterized by immunohistochemistry, Western blotting, and cell proliferation assays. Tumorigenicity was confirmed by soft agar growth and the ability to form tumors in a mouse xenograft model. Exome and RNA sequencing of patient tumor samples and cell lines was performed using standard protocols.

RESULTS

Three typical carcinoid tumor lines grew as adherent monolayers in vitro, expressed neuroendocrine markers consistent with the primary tumor, and formed colonies in soft agar. A single cell line produced lung tumors in nude mice after intravenous injection. Exome and RNA sequencing of this cell line showed lineage relationship with the primary tumor, and demonstrated mutations in a number of genes related to neuronal differentiation.

CONCLUSION

Three human pulmonary typical carcinoid tumor cell lines have been generated and characterized as a tool for studying the biology and novel treatment approaches for these rare tumors.

Randomized controlled trial of oral glutathione supplementation on body stores of glutathione

PURPOSE

Glutathione (GSH), the most abundant endogenous antioxidant, is a critical regulator of oxidative stress and immune function. While oral GSH has been shown to be bioavailable in laboratory animal models, its efficacy in humans has not been established. Our objective was to determine the long-term effectiveness of oral GSH supplementation on body stores of GSH in healthy adults.

METHODS

A 6-month randomized, double-blinded, placebo-controlled trial of oral GSH (250 or 1,000 mg/day) on GSH levels in blood, erythrocytes, plasma, lymphocytes and exfoliated buccal mucosal cells was conducted in 54 non-smoking adults. Secondary outcomes on a subset of subjects included a battery of immune markers.

RESULTS

GSH levels in blood increased after 1, 3 and 6 months versus baseline at both doses. At 6 months, mean GSH levels increased 30-35 % in erythrocytes, plasma and lymphocytes and 260 % in buccal cells in the high-dose group (P < 0.05). GSH levels increased 17 and 29 % in blood and erythrocytes, respectively, in the low-dose group (P < 0.05). In most cases, the increases were dose and time dependent, and levels returned to baseline after a 1-month washout period. A reduction in oxidative stress in both GSH dose groups was indicated by decreases in the oxidized to reduced glutathione ratio in whole blood after 6 months. Natural killer cytotoxicity increased >twofold in the high-dose group versus placebo (P < 0.05) at 3 months.

CONCLUSIONS

These findings show, for the first time, that daily consumption of GSH supplements was effective at increasing body compartment stores of GSH.

Capillary electrophoresis based on the nucleic acid detection in the application of cancer diagnosis and therapy

This review focuses on capillary electrophoresis-based nucleic acid detection as it is applied to cancer diagnosis and therapy, and provides an introduction to the drawbacks and future developments of analysis with CE.

Glutathione defense mechanism in liver injury: insights from animal models

Glutathione (GSH) is the most abundant cellular thiol antioxidant and it exhibits numerous and versatile functions. Disturbances in GSH homeostasis have been associated with liver diseases induced by drugs, alcohol, diet and environmental pollutants. Until recently, our laboratories and others have developed mouse models with genetic deficiencies in glutamate-cysteine ligase (GCL), the rate-limiting enzyme in the GSH biosynthetic pathway. This review focuses on regulation of GSH homeostasis and, specifically, recent studies that have utilized such GSH-deficient mouse models to investigate the role of GSH in liver disease processes. These studies have revealed a differential hepatic response to distinct profiles of hepatic cellular GSH concentration. In particular, mice engineered to not express the catalytic subunit of GCL in hepatocytes [Gclc(h/h) mice] experience almostcomplete loss of hepatic GSH (to 5% of normal) and develop spontaneous liver pathologies characteristic of various clinical stages of liver injury. In contrast, mice globally engineered to not express the modifier subunit of GCL [Gclm⁻/⁻ mice] show a less severe hepatic GSH deficit (to ≈15% of normal) and exhibit overall protection against liver injuries induced by a variety of hepatic insults. Collectively, these transgenic mouse models provide interesting new insights regarding pathophysiological functions of GSH in the liver.