Genetic Modifiers of Progression-Free Survival in Never-Smoking Lung Adenocarcinoma Patients Treated with First-Line Tyrosine Kinase Inhibitors

Decoding TDP-43: the molecular chameleon of neurodegenerative diseases

TAR DNA-binding protein 43 (TDP-43) has emerged as a critical player in neurodegenerative disorders, with its dysfunction implicated in a wide spectrum of diseases including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and Alzheimer's disease (AD). This comprehensive review explores the multifaceted roles of TDP-43 in both physiological and pathological contexts. We delve into TDP-43's crucial functions in RNA metabolism, including splicing regulation, mRNA stability, and miRNA biogenesis. Particular emphasis is placed on recent discoveries regarding TDP-43's involvement in DNA interactions and chromatin dynamics, highlighting its broader impact on gene expression and genome stability. The review also examines the complex pathogenesis of TDP-43-related disorders, discussing the protein's propensity for aggregation, its effects on mitochondrial function, and its non-cell autonomous impacts on glial cells. We provide an in-depth analysis of TDP-43 pathology across various neurodegenerative conditions, from well-established associations in ALS and FTLD to emerging roles in diseases such as Huntington's disease and Niemann-Pick C disease. The potential of TDP-43 as a therapeutic target is explored, with a focus on recent developments in targeting cryptic exon inclusion and other TDP-43-mediated processes. This review synthesizes current knowledge on TDP-43 biology and pathology, offering insights into the protein's central role in neurodegeneration and highlighting promising avenues for future research and therapeutic interventions.

Implications of TDP-43 in non-neuronal systems

TAR DNA-binding protein 43 (TDP-43) is a versatile RNA/DNA-binding protein with multifaceted processes. While TDP-43 has been extensively studied in the context of degenerative diseases, recent evidence has also highlighted its crucial involvement in diverse life processes beyond neurodegeneration. Here, we mainly reviewed the function of TDP-43 in non-neurodegenerative physiological and pathological processes, including spermatogenesis, embryonic development, mammary gland development, tumor formation, and viral infection, highlighting its importance as a key regulatory factor for the maintenance of normal functions throughout life. TDP-43 exhibits diverse and sometimes opposite functionality across different cell types through various mechanisms, and its roles can shift at distinct stages within the same biological system. Consequently, TDP-43 operates in both a context-dependent and a stage-specific manner in response to a variety of internal and external stimuli. Video Abstract.

Genome-wide association study of lung adenocarcinoma in East Asia and comparison with a European population

Lung adenocarcinoma is the most common type of lung cancer. Known risk variants explain only a small fraction of lung adenocarcinoma heritability. Here, we conducted a two-stage genome-wide association study of lung adenocarcinoma of East Asian ancestry (21,658 cases and 150,676 controls; 54.5% never-smokers) and identified 12 novel susceptibility variants, bringing the total number to 28 at 25 independent loci. Transcriptome-wide association analyses together with colocalization studies using a Taiwanese lung expression quantitative trait loci dataset (n = 115) identified novel candidate genes, including FADS1 at 11q12 and ELF5 at 11p13. In a multi-ancestry meta-analysis of East Asian and European studies, four loci were identified at 2p11, 4q32, 16q23, and 18q12. At the same time, most of our findings in East Asian populations showed no evidence of association in European populations. In our studies drawn from East Asian populations, a polygenic risk score based on the 25 loci had a stronger association in never-smokers vs. individuals with a history of smoking (Pinteraction = 0.0058). These findings provide new insights into the etiology of lung adenocarcinoma in individuals from East Asian populations, which could be important in developing translational applications.

Strategies to investigate and mitigate collider bias in genetic and Mendelian randomisation studies of disease progression

Genetic studies of disease progression can be used to identify factors that may influence survival or prognosis, which may differ from factors that influence on disease susceptibility. Studies of disease progression feed directly into therapeutics for disease, whereas studies of incidence inform prevention strategies. However, studies of disease progression are known to be affected by collider (also known as "index event") bias since the disease progression phenotype can only be observed for individuals who have the disease. This applies equally to observational and genetic studies, including genome-wide association studies and Mendelian randomisation (MR) analyses. In this paper, our aim is to review several statistical methods that can be used to detect and adjust for index event bias in studies of disease progression, and how they apply to genetic and MR studies using both individual- and summary-level data. Methods to detect the presence of index event bias include the use of negative controls, a comparison of associations between risk factors for incidence in individuals with and without the disease, and an inspection of Miami plots. Methods to adjust for the bias include inverse probability weighting (with individual-level data), or Slope-Hunter and Dudbridge et al.'s index event bias adjustment (when only summary-level data are available). We also outline two approaches for sensitivity analysis. We then illustrate how three methods to minimise bias can be used in practice with two applied examples. Our first example investigates the effects of blood lipid traits on mortality from coronary heart disease, while our second example investigates genetic associations with breast cancer mortality.

Recalibrating Risk Prediction Models by Synthesizing Data Sources: Adapting the Lung Cancer PLCO Model for Taiwan

BACKGROUND

Methods synthesizing multiple data sources without prospective datasets have been proposed for absolute risk model development. This study proposed methods for adapting risk models for another population without prospective cohorts, which would help alleviate the health disparities caused by advances in absolute risk models. To exemplify, we adapted the lung cancer risk model PLCOM2012, well studied in the west, for Taiwan.

METHODS

Using Taiwanese multiple data sources, we formed an age-matched case-control study of ever-smokers (AMCCSE), estimated the number of ever-smoking lung cancer patients in 2011-2016 (NESLP2011), and synthesized a dataset resembling the population of cancer-free ever-smokers in 2010 regarding the PLCOM2012 risk factors (SPES2010). The AMCCSE was used to estimate the overall calibration slope, and the requirement that NESLP2011 equals the estimated total risk of individuals in SPES2010 was used to handle the calibration-in-the-large problem.

RESULTS

The adapted model PLCOT-1 (PLCOT-2) had an AUC of 0.78 (0.75). They had high performance in calibration and clinical usefulness on subgroups of SPES2010 defined by age and smoking experience. Selecting the same number of individuals for low-dose computed tomography screening using PLCOT-1 (PLCOT-2) would have identified approximately 6% (8%) more lung cancers than the US Preventive Services Task Forces 2021 criteria. Smokers having 40+ pack-years had an average PLCOT-1 (PLCOT-2) risk of 3.8% (2.6%).

CONCLUSIONS

The adapted PLCOT models had high predictive performance.

IMPACT

The PLCOT models could be used to design lung cancer screening programs in Taiwan. The methods could be applicable to other cancer models.

LncRNAs LCETRL3 and LCETRL4 at chromosome 4q12 diminish EGFR-TKIs efficiency in NSCLC through stabilizing TDP43 and EIF2S1

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) are effective targeted therapy drugs for advanced non-small cell lung cancer (NSCLC) patients carrying sensitized EGFR mutations. The rapid development of EGFR-TKIs resistance represents a major clinical challenge for managing NSCLC. The chromosome 4q12 is the first genome-wide association study (GWAS)-reported locus associated with progression-free survival (PFS) of NSCLC patients treated with EGFR-TKIs. However, the biological significance of the noncoding transcripts at 4q12 in NSCLC remains elusive. In the present study, we identified two 4q12 long noncoding RNAs (lncRNAs) LCETRL3 and LCETRL4 which could significantly dimmish EGFR-TKIs efficiency. In line with their oncogenic role, evidently higher LCETRL3 and LCETRL4 levels were observed in NSCLC tissues as compared with normal specimens. Importantly, lncRNA LCETRL3 can interact with oncoprotein TDP43 and inhibit ubiquitination and degradation of TDP43. Similarly, lncRNA LCETRL4 can bind and stabilize oncoprotein EIF2S1 through reducing ubiquitin-proteasome degradation of EIF2S1. In particular, elevated levels of LCETRL3 or LCETRL4 in NSCLC cells resulted in stabilization of TDP43 or EIF2S1, increased levels of NOTCH1 or phosphorylated PDK1, activated AKT signaling and, thus, EGFR-TKIs resistance. Taken together, our data revealed a novel model that integrates two lncRNAs transcribed from the 4q12 locus into the regulation of EGFR-TKIs resistance in NSCLC. These findings shed new light on the importance of functionally annotating lncRNAs in the GWAS loci and provided insights to declare novel druggable targets, i.e., lncRNAs, which may unlock the therapeutic potential of EGFR-TKIs resistant NSCLC in the clinic.

Nuclear Pore Glycoprotein 62 Genetic Variant rs9523 is Associated with Clinical Outcomes of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Lung Adenocarcinoma Patients

Introduction

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have represented the prototype of targeted therapy in NSCLC. Patients with EGFR-mutant lung adenocarcinoma extract an extraordinary clinical benefit from EGFR-TKIs. However, the extent and duration of these responses are heterogeneous, suggesting the existence of genetic modifiers affecting an individual’s response to TKIs. We investigated whether genetic variants in miRNA binding sites are associated with the clinical outcome of EGFR-TKIs in lung adenocarcinoma patients.

Methods

One hundred SNPs at miRNA binding sites in cancer-related genes were selected for the analysis using the crosslinking, ligation and sequencing of hybrids (CLASH) and CancerGenes database. qRT-PCR and luciferase assays were conducted to evaluate the functional relevance of the SNPs.

Results

NUP62 rs9523A>G were significantly associated with worse response to EGFR-TKIs, overall survival (OS), and progression-free survival (PFS). The other three SNPs (DVL2 rs2074216G>A, ARF1 rs11541557G>T, and UHRF1 rs2261988C>A) were significantly associated with worse OS and PFS. The rs9523A>G was significantly associated with decreased NUP62 expression in tumor tissues. In addition, a significantly decreased luciferase activity was noted in NUP62 rs9523 G allele compared to A allele.

Conclusion

Genetic variants in miRNA binding sites, especially NUP62 rs9523A>G, may be useful in predicting the clinical outcomes of EGFR-mutant lung adenocarcinoma patients treated with EGFR-TKIs.

Programmed Death Ligand 2 Gene Polymorphisms Are Associated With Lung Adenocarcinoma Risk in Female Never-Smokers

Objectives

Lung cancer in never-smokers is a distinct disease associated with a different genomic landscape, pathogenesis, risk factors, and immune checkpoint inhibitor responses compared to those observed in smokers. This study aimed to identify novel single nucleotide polymorphisms (SNPs) of programmed death-1 (encoded by PDCD1) and its ligands, programmed death ligand 1 (CD274) and 2 (PDCD1LG2), associated with lung cancer risk in never-smoking women.

Materials and Methods

During September 2002 and July 2012, we enrolled never-smoking female patients with lung adenocarcinoma (LUAD) (n=1153) and healthy women (n=1022) from six tertiary hospitals in Taiwan. SNP data were obtained and analyzed from the genome-wide association study dataset and through an imputation method. The expression quantitative trait loci (eQTL) analysis was performed in both tumor and non-tumor tissues for the correlation between genetic expression and identified SNPs.

Results

A total of 12 PDCD1LG2 SNPs related to LUAD risk were identified in never-smoking women, including rs2381282, rs4742103, rs4237162, rs4742104, rs12237624, rs78096119, rs6476988, rs7857315, rs10975178, rs7854413, rs56001683, and rs7858319. Among them, six tagged PDCD1LG2 SNPs rs2381282, rs4742103, rs4237162, rs4742104, rs78096119, and rs56001683 were significantly associated with LUAD risk. Specifically, two PDCD1LG2 SNPs, rs12237624 and rs78096119, were associated with previous pulmonary tuberculosis infection in relation to LUAD susceptibility. Through an eQTL assay, we found that rs2381282 (p < 0.001), rs12237624 (p = 0.019), and rs78096119 (p = 0.019) were associated with the expression levels of programed death ligand 2.

Conclusions

Novel SNPs of programed death ligand 2 associated with lung adenocarcinoma risk were identified. Among them, two SNPs were associated with pulmonary tuberculosis infection in relation to lung adenocarcinoma susceptibility. These SNPs may help to stratify high-risk populations of never-smokers during lung cancer screening.

miR-1262 Transcriptionally Modulated by an Enhancer Genetic Variant Improves Efficiency of Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors in Advanced Lung Adenocarcinoma

Advanced nonsmall-cell lung cancer (NSCLC) patients with mutated epidermal growth factor receptor (EGFR) can remarkably benefit from target therapy of EGFR-tyrosine kinase inhibitors (TKIs). However, increasing drug sensitivity and improving outcomes of NSCLC patients to EGFR-TKI therapy remains a challenge. Several studies have shown a link between microRNAs and drug resistance in cancer. In this study, we hypothesized that the rs12740674 single nucleotide polymorphism in the enhancer of miR-1262 may affect its expression, which may impact the outcome of NSCLC patients treated with EGFR-TKIs. The rs12740674 polymorphism was genotyped in two independent cohorts, including 319 EGFR-TKI treated stage IIIB/IV NSCLC patients. The allele-specific regulation on miR-1262 transcription by rs12740674 and impacts of miR-1262 on gefitinib sensitivity were evaluated in vitro and in vivo. Cox regression analyses indicated that the rs12740674 T allele was significantly associated with short survival time in both cohorts (p < 0.05). Luciferase assays demonstrated that the rs12740674 T allelic enhancer showed weaker capability to promote miR-1262 transcription compared with the C allelic enhancer, which may be due to reduced transcription factor binding according to electrophoretic mobility shift assays. Furthermore, significantly decreased miR-1262 expression in NSCLC and nontumor lung tissues of T allele carriers was observed compared with levels in C allele carriers. Moreover, miR-1262 expression enhanced the anticancer effects of gefitinib on NSCLC cells. Our data indicate that miR-1262 may be a potential therapeutic target for NSCLC.

CaSR Induces Osteoclast Differentiation and Promotes Bone Metastasis in Lung Adenocarcinoma

Objective: Explore the mechanism of CaSR's involvement in bone metastasis in lung adenocarcinoma.

Methods: Immunohistochemistry (IHC) was used to detect the expression of calcium-sensing receptor (CaSR) in 120 cases of lung adenocarcinoma with bone metastasis. Stably transfected cell lines with CaSR overexpression and knockdown based on A549 cells were constructed. The expression of CaSR was verified by western blot and qPCR. The proliferation and migration abilities of A549 cells were tested using cholecystokinin-8 (CCK-8) and Transwell assays, respectively. Western blotting was used to detect the expression of matrix metalloproteinases MMP2, MMP9, CaSR, and NF-κB. The supernatant from each cell culture group was collected as a conditional co-culture solution to study the induction of osteoclast precursor cells and osteoblasts. Western blot and qPCR were used to validate the expression of bone matrix degradation-related enzymes cathepsin K and hormone calcitonin receptor (CTR) and osteoblast-induced osteoclast maturation and differentiation enzyme receptor activator of nuclear factor-κB ligand (RANKL), macrophage colony-stimulating factor (M-CSF), osteoprotegerin (OPG), and PTHrP. Immunofluorescent staining was used to detect F-actin ring formation and osteocalcin expression. Western blot results for NF-κB expression identified a regulatory relationship between NF-κB and CaSR.

Results: CaSR expression in lung cancer tissues was significantly higher than that in adjacent and normal lung tissues. The expression of CaSR in lung cancer tissues with bone metastasis was higher than that in non-metastatic lung cancer tissues. The proliferation and migration ability of A549 cells increased significantly with overexpressed CaSR. The co-culture solution directly induced osteoclast precursor cells and the expression of bone matrix degradation-related enzymes significantly increased. Osteoblasts were significantly inhibited and osteoblast-induced osteoclast maturation and differentiation enzymes were significantly downregulated. It was found that the expression of NF-κB and PTHrP increased when CaSR was overexpressed. Osteoclast differentiation factor expression was also significantly increased, which directly induces osteoclast differentiation and maturation. These results were reversed when CaSR was knocked down.

Conclusions: CaSR can positively regulate NF-κB and PTHrP expression in A549 cells with a high metastatic potential, thereby promoting osteoclast differentiation and maturation, and facilitating the occurrence and development of bone metastasis in lung adenocarcinoma.

Predicting Lung Cancer Occurrence in Never-Smoking Females in Asia: TNSF-SQ, a Prediction Model

BACKGROUND

High disease burden suggests the desirability to identify high-risk Asian never-smoking females (NSF) who may benefit from low-dose CT (LDCT) screening. In North America, one is eligible for LDCT screening if one satisfies the U.S. Preventive Services Task Force (USPSTF) criteria or has model-estimated 6-year risk greater than 0.0151. According to two U.S. reports, only 36.6% female patients with lung cancer met the USPSTF criteria, while 38% of the ever-smokers ages 55 to 74 years met the USPSTF criteria.

METHODS

Using data on NSFs in the Taiwan Genetic Epidemiology Study of Lung Adenocarcinoma and the Taiwan Biobank before August 2016, we formed an age-matched case-control study consisting of 1,748 patients with lung cancer and 6,535 controls. Using these and an estimated age-specific lung cancer 6-year incidence rate among Taiwanese NSFs, we developed the Taiwanese NSF Lung Cancer Risk Models using genetic information and simplified questionnaire (TNSF-SQ). Performance evaluation was based on the newer independent datasets: Taiwan Lung Cancer Pharmacogenomics Study (LCPG) and Taiwan Biobank data after August 2016 (TWB2).

RESULTS

The AUC based on the NSFs ages 55 to 70 years in LCPG and TWB2 was 0.714 [95% confidence intervals (CI), 0.660-0.768]. For women in TWB2 ages 55 to 70 years, 3.94% (95% CI, 2.95-5.13) had risk higher than 0.0151. For women in LCPG ages 55 to 74 years, 27.03% (95% CI, 19.04-36.28) had risk higher than 0.0151.

CONCLUSIONS

TNSF-SQ demonstrated good discriminative power. The ability to identify 27.03% of high-risk Asian NSFs ages 55 to 74 years deserves attention.

IMPACT

TNSF-SQ seems potentially useful in selecting Asian NSFs for LDCT screening.

Expression of the Major and Pro-Oncogenic H3K9 Lysine Methyltransferase SETDB1 in Non-Small Cell Lung Cancer

SETDB1 is a key histone lysine methyltransferase involved in gene silencing. The SETDB1 gene is amplified in human lung cancer, where the protein plays a driver role. Here, we investigated the clinical significance of SETDB1 expression in the two major forms of human non-small cell lung carcinoma (NSCLC), i.e., adenocarcinoma (ADC) and squamous cell carcinoma (SCC), by combining a meta-analysis of transcriptomic datasets and a systematic review of the literature. A total of 1140 NSCLC patients and 952 controls were included in the association analyses. Our data revealed higher levels of SETDB1 mRNA in ADC (standardized mean difference, SMD: 0.88; 95% confidence interval, CI: 0.73-1.02; p < 0.001) and SCC (SMD: 0.40; 95% CI: 0.13-0.66; p = 0.003) compared to non-cancerous tissues. For clinicopathological analyses, 2533 ADC and 903 SCC patients were included. Interestingly, SETDB1 mRNA level was increased in NSCLC patients who were current smokers compared to non-smokers (SMD: 0.26; 95% CI: 0.08-0.44; p = 0.004), and when comparing former smokers and non-smokers (p = 0.009). Furthermore, the area under the curve (AUC) given by the summary receiver operator characteristic curve (sROC) was 0.774 (Q = 0.713). Together, our findings suggest a strong foundation for further research to evaluate SETDB1 as a diagnostic biomarker and/or its potential use as a therapeutic target in NSCLC.

Adjustment for index event bias in genome-wide association studies of subsequent events

Following numerous genome-wide association studies of disease susceptibility, there is increasing interest in genetic associations with prognosis, survival or other subsequent events. Such associations are vulnerable to index event bias, by which selection of subjects according to disease status creates biased associations if common causes of incidence and prognosis are not accounted for. We propose an adjustment for index event bias using the residuals from the regression of genetic effects on prognosis on genetic effects on incidence. Our approach eliminates this bias when direct genetic effects on incidence and prognosis are independent, and otherwise reduces bias in realistic situations. In a study of idiopathic pulmonary fibrosis, we reverse a paradoxical association of the strong susceptibility gene MUC5B with increased survival, suggesting instead a significant association with decreased survival. In re-analysis of a study of Crohn’s disease prognosis, four regions remain associated at genome-wide significance but with increased standard errors.

Different from GWAS for susceptibility to disease, GWAS for prognosis or survival may be vulnerable to selection bias. Here, Dudbridge et al present an approach to reduce index event bias in simulated and realistic situations, and apply it to GWAS of survival with idiopathic pulmonary fibrosis and Crohn’s disease prognosis.

The Roles of Common Variation and Somatic Mutation in Cancer Pharmacogenomics

Cancer pharmacogenomics is the science concerned with understanding genetic alterations and its effects on the pharmacokinetics and pharmacodynamics of anti-cancer drugs, with the aim to provide cancer patients with the precise medication that will achieve a good response and cause low/no incidence of adverse events. Advances in biotechnology and bioinformatics have enabled genomic research to evolve from the evaluation of alterations at the single-gene level to studies on the whole-genome scale using large-scale genotyping and next generation sequencing techniques. International collaborative efforts have resulted in the construction of databases to curate the identified genetic alterations that are clinically significant, and these are currently utilized in clinical sequencing and liquid biopsy screening/monitoring. Furthermore, countless clinical studies have accumulated sufficient evidence to match cancer patients to therapies by utilizing the information of clinical-relevant alterations. In this review we summarize the importance of germline alterations that act as predictive biomarkers for drug-induced toxicity and drug response as well as somatic mutations in cancer cells that function as drug targets. The integration of genomics into the medical field has transformed the era of cancer therapy from one-size-fits-all to cancer precision medicine.

Clinical efficacy of icotinib in patients with advanced nonsquamous non-small cell lung cancer with unknown EGFR mutation status that failed to respond to second-line chemotherapy

Background

Evaluation of the clinical efficacy and safety of icotinib in advanced nonsquamous non-small cell lung cancer (NSCLC) patients with an unknown EGFR mutation who failed to respond to second-line chemotherapy.

Methods

Seventy-six cases of advanced nonsquamous NSCLC were involved in this study from seven hospitals from the Hubei province of China. Patients with an unknown EGFR mutation status were treated with Icotinib, at an oral dosage of 125 mg three times daily. All patients were followed up for at least 1 year to observe the efficacy, adverse reactions, and 1-year survival.

Results

The patients' overall objective response rate (ORR) was 34.2%, the disease control rate (DCR) was 75.0%, the clinical benefit rate (CBR) was 80.2%, the median progression-free survival (PFS) was 11.0 months, the median overall survival (OS) was 16.9 months, and the 1-year OS rate was 63.2%. Gender and smoking history were associated with the DCR (P<0.05). Both PFS and OS were significantly higher in groups that had pre-accepted ≤6 cycles of chemotherapy than in groups that had pre-accepted >6 cycles.

Conclusions

Our results demonstrated that icotinib had a better DCR or clinical benefits for treating the patients with unknown EGFR mutation who failed to respond to second-line chemotherapy in advanced nonsquamous NSCLC, and the adverse effects are tolerable.

Genetic variant of IRAK2 in the toll-like receptor signaling pathway and survival of non-small cell lung cancer

The toll-like receptor (TLR) signaling pathway plays an important role in the innate immune responses and antigen-specific acquired immunity. Aberrant activation of the TLR pathway has a significant impact on carcinogenesis or tumor progression. Therefore, we hypothesize that genetic variants in the TLR signaling pathway genes are associated with overall survival (OS) of patients with non-small cell lung cancer (NSCLC). To test this hypothesis, we first performed Cox proportional hazards regression analysis to evaluate associations between genetic variants of 165 TLR signaling pathway genes and NSCLC OS using the genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). The results were further validated by the Harvard Lung Cancer Susceptibility GWAS dataset. Specifically, we identified IRAK2 rs779901 C > T as a predictor of NSCLC OS, with a variant-allele (T) attributed hazards ratio (HR) of 0.78 [95% confidence interval (CI) = 0.67-0.91, P = 0.001] in the PLCO dataset, 0.84 (0.72-0.98, 0.031) in the Harvard dataset, and 0.81 (0.73-0.90, 1.08x10-4 ) in the meta-analysis of these two GWAS datasets. In addition, the T allele was significantly associated with an increased mRNA expression level of IRAK2. Our findings suggest that IRAK2 rs779901 C > T may be a promising prognostic biomarker for NSCLC OS.

Upregulation of CISD2 augments ROS homeostasis and contributes to tumorigenesis and poor prognosis of lung adenocarcinoma

CISD2 is a redox-sensitive gene critical for normal development and mitochondrial integrity. CISD2 was known to have aberrant expression in several types of human cancers. However, its relation with lung cancer is still not clear. In this study we found CISD2 mRNA was significantly upregulated in lung adenocarcinoma (ADC) samples, compared with their adjacent normal counterparts, and was correlated with tumor stage, grade, and prognosis based on analysis of clinical specimens-derived expression data in public domain and our validation assay. Cell based assay indicated that CISD2 expression regulated accumulation of reactive oxygen species (ROS), polarization of mitochondrial membrane potential, as well as cell viability, apoptosis, invasiveness, and tumorigenicity. In addition, CISD2 expression was found significantly correlated with stress response/redox signaling genes such as EGR1 and GPX3, while such correlations were also found valid in many public domain data. Taken together, upregulation of CISD2 is involved in an increased antioxidant capacity in response to elevated ROS levels during the formation and progression of lung ADC. The molecular mechanism underlying how CISD2 regulates ROS homeostasis and augments malignancy of lung cancer warrants further investigations.