Telomere attrition and genomic instability in unexplained recurrent pregnancy loss in humans: A preliminary study.

Genome instability is defined as an elevated rate of DNA damage and mutations as a result of exposure to potential direct and indirect mutagens. This current investigation was designed to elucidate the genomic instability among couples experiencing unexplained recurrent pregnancy loss (uRPL). A cohort of 1272 individuals with history of unexplained RPL with normal karyotype was retrospectively screened for levels of intracellular ROS production, baseline genomic instability and telomere functionality. The experimental outcome was compared with 728 fertile control individuals. In this study, it was perceived that individuals with uRPL exhibited higher intracellular oxidative stress, along with higher basal levels of genomic instability as compared with the fertile controls. This observation elucidates the role of genomic instability as well as involvement of telomeres in cases of uRPL. It was also observed that higher oxidative stress might be associated with DNA damage and telomere dysfunction resulting in genomic instability among subjects with unexplained RPL. This study highlighted the assessment of genomic instability status in individuals experiencing uRPL.

Assessment of hOGG1 Genetic Polymorphism (rs1052133) and DNA Damage in Radiation-Exposed Workers.

OBJECTIVE: The aim of this study was to assess the effect of radiation exposure, human 8-oxoguanine DNA N-glycosylase-1 (hOGG1) exon 7 genetic polymorphism and confounding factors on DNA damage response. METHODS: Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and alkaline Comet assay method were applied to determine the hOGG1 genetic polymorphisms and DNA damage response. A total of 80 participants were enrolled in this study, consisting of 40 radiation-exposed workers as a case group and 40 non-radiation workers as a control group. RESULT: The genotypes frequencies for controls were Ser/Ser (35%), Ser/Cys (32.5%), and Cys/Cys (32.5%), with frequencies of alleles being 326Ser (0.52) and 326Cys (0.48), whereas the genotypes frequencies for radiation-exposed workers (cases group) were Ser/Ser (17.5%), Ser/Cys (57.5%), and Cys/Cys (25%), with frequencies of alleles being 326Ser (0.46) and 326Cys (0.54). The results indicated that DNA damage response were not significantly higher in the exposed workers than in controls (22.55 ± 6.02 versus 21.72 ± 7.14; P=0.58). The time of exposure has a significantly negative correlation with comet tail length value among radiation workers. In addition, it was found that the DNA damage response was strongly associated with age and time of exposure with a decrease of 0.6 percent (P-value: 0.008) and 0.58 percent (P-value: 0.009), respectively. Whereas gender, smoking habit, and equivalent dose were not correlated with DNA damage. CONCLUSION: The single-nucleotide polymorphism of hOGG1 exon 7 (rs1052133) demonstrated no association with the extent of DNA damage in radiation-exposed workers.

Integrative epigenomic and transcriptomic analyses reveal metabolic switching by intermittent fasting in brain.

Intermittent fasting (IF) remains the most effective intervention to achieve robust anti-aging effects and attenuation of age-related diseases in various species. Epigenetic modifications mediate the biological effects of several environmental factors on gene expression; however, no information is available on the effects of IF on the epigenome. Here, we first found that IF for 3 months caused modulation of H3K9 trimethylation (H3K9me3) in the cerebellum, which in turn orchestrated a plethora of transcriptomic changes involved in robust metabolic switching processes commonly observed during IF. Second, a portion of both the epigenomic and transcriptomic modulations induced by IF was remarkably preserved for at least 3 months post-IF refeeding, indicating that memory of IF-induced epigenetic changes was maintained. Notably, though, we found that termination of IF resulted in a loss of H3K9me3 regulation of the transcriptome. Collectively, our study characterizes the novel effects of IF on the epigenetic-transcriptomic axis, which controls myriad metabolic processes. The comprehensive analyses undertaken in this study reveal a molecular framework for understanding how IF impacts the metabolo-epigenetic axis of the brain and will serve as a valuable resource for future research.

A Novel Balanced Chromosomal Translocation in an Azoospermic Male: A Case Report.

BACKGROUND: Balanced translocation and azoospermia as two main reasons for recurrent pregnancy loss are known to be the leading causes of infertility across the world. Balanced translocations in azoospermic males are very rare and extensive studies need to be performed to elucidate the translocation status of the affected individuals. CASE PRESENTAION: The cytogenetic characterization of a 28 year old male and his female partner is reported in this study. The male partner was diagnosed with non-obstructive azoospermia (NOA) and the couple was unable to conceive. Cytogenetic analysis by karyotyping through Giemsa-trypsin-giemsa banding technique (GTG) showed a novel balanced translocation, 46,XY,t(19;22)(19q13.4;22q11.2), 13ps+ in the male and the female karyotype was found to be 46,XX. Multicolor fluorescence in situ hybridization (mFISH) analysis on paternal chromosomal preparations confirmed both the region and origin of balanced translocation. The status of Y chromosome microdeletion (YMD) was analyzed and no notable microdeletion was observed. Furthermore, protein-protein interaction (PPI) network analysis was performed for breakpoint regions to explore the possible functional genetic associations. CONCLUSION: The azoospermic condition of the male patient along with novel balanced chromosomal translocation was responsible for infertility irrespective of its YMD status. Therefore, cytogenetic screening of azoospermic patients should be performed in addition to routine semen analysis to rule out or to confirm presence of any numerical or structural anomaly in the patient.

Investigations on the new mechanism of action for acetaldehyde-induced clastogenic effects in human lung fibroblasts.

Acetaldehyde (AA) has been classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC, WHO) and by the US Environmental Protection Agency due to its ability to cause tumours following inhalation or alcohol consumption in animals. Humans are constantly exposed to AA through inhalation from the environment through cigarette smoke, vehicle fumes and industrial emissions as well as by persistent alcohol ingestion. Individuals with deficiencies in the enzymes that are involved in the metabolism of AA are more susceptible to its toxicity and constitute a vulnerable human population. Studies have shown that AA induces DNA damage and cytogenetic abnormalities. A study was undertaken to elucidate the clastogenic effects induced by AA and any preceding DNA damage that occurs in normal human lung fibroblasts as this will further validate the detrimental effects of inhalation exposure to AA. AA exposure induced DNA damage, involving DNA double strand breaks, which could possibly occur at the telomeric regions as well, resulting in a clastogenic effect and subsequent genomic instability, which contributed to the cell cycle arrest. The clastogenic effect induced by AA in human lung fibroblasts was evidenced by micronuclei induction and chromosomal aberrations, including those at the telomeric regions. Co-localisation between the DNA double strand breaks and telomeric regions was observed, suggesting possible induction of DNA double strand breaks due to AA exposure at the telomeric regions as a new mechanism beyond the clastogenic effect of AA. From the cell cycle profile following AA exposure, a G2/M phase arrest and a decrease in cell viability were also detected. Therefore, these effects due to AA exposure via inhalation may have implications in the development of carcinogenesis in humans.

Prediction of the Acute or Late Radiation Toxicity Effects in Radiotherapy Patients Using Ex Vivo Induced Biodosimetric Markers: A Review.

A search for effective methods for the assessment of patients' individual response to radiation is one of the important tasks of clinical radiobiology. This review summarizes available data on the use of ex vivo cytogenetic markers, typically used for biodosimetry, for the prediction of individual clinical radiosensitivity (normal tissue toxicity, NTT) in cells of cancer patients undergoing therapeutic irradiation. In approximately 50% of the relevant reports, selected for the analysis in peer-reviewed international journals, the average ex vivo induced yield of these biodosimetric markers was higher in patients with severe reactions than in patients with a lower grade of NTT. Also, a significant correlation was sometimes found between the biodosimetric marker yield and the severity of acute or late NTT reactions at an individual level, but this observation was not unequivocally proven. A similar controversy of published results was found regarding the attempts to apply G2- and γH2AX foci assays for NTT prediction. A correlation between ex vivo cytogenetic biomarker yields and NTT occurred most frequently when chromosome aberrations (not micronuclei) were measured in lymphocytes (not fibroblasts) irradiated to relatively high doses (4-6 Gy, not 2 Gy) in patients with various grades of late (not early) radiotherapy (RT) morbidity. The limitations of existing approaches are discussed, and recommendations on the improvement of the ex vivo cytogenetic testing for NTT prediction are provided. However, the efficiency of these methods still needs to be validated in properly organized clinical trials involving large and verified patient cohorts.

Massively parallel single-molecule telomere length measurement with digital real-time PCR.

Telomere length is a promising biomarker for age-associated diseases and cancer, but there are still substantial challenges to routine telomere analysis in clinics because of the lack of a simple and rapid yet scalable method for measurement. We developed the single telomere absolute-length rapid (STAR) assay, a novel high-throughput digital real-time PCR approach for rapidly measuring the absolute lengths and quantities of individual telomere molecules. We show that this technique provides the accuracy and sensitivity to uncover associations between telomere length distribution and telomere maintenance mechanisms in cancer cell lines and primary tumors. The results indicate that the STAR assay is a powerful tool to enable the use of telomere length distribution as a biomarker in disease and population-wide studies.

High glucose alters the DNA methylation pattern of neurodevelopment associated genes in human neural progenitor cells in vitro.

Maternal diabetes alters the global epigenetic mechanisms and expression of genes involved in neural tube development in mouse embryos. Since DNA methylation is a critical epigenetic mechanism that regulates gene functions, gene-specific DNA methylation alterations were estimated in human neural progenitor cells (hNPCs) exposed to high glucose (HG) in the present study. The DNA methylation pattern of genes involved in several signalling pathways including axon guidance (SLIT1-ROBO2 pathway), and Hippo pathway (YAP and TAZ) was altered in hNPCs exposed to HG. The expression levels of SLIT1-ROBO2 pathways genes (including its effectors, SRGAP1 and CDC42) which mediates diverse cellular processes such as proliferation, neurogenesis and axon guidance, and Hippo pathway genes (YAP and TAZ) which regulates proliferation, stemness, differentiation and organ size were downregulated in hNPCs exposed to HG. A recent report suggests a possible cross-talk between SLIT1-ROBO2 and TAZ via CDC42, a mediator of actin dynamics. Consistent with this, SLIT1 knockdown downregulated the expression of its effectors and TAZ in hNPCs, suggesting that HG perturbs the cross-talk between SLIT1-ROBO2 and TAZ in hNPCs. Overall, this study demonstrates that HG epigenetically alters the SLIT1-ROBO2 and Hippo signalling pathways in hNPCs, forming the basis for neurodevelopmental disorders in offspring of diabetic pregnancy.

Combined treatment with cisplatin and the tankyrase inhibitor XAV-939 increases cytotoxicity, abrogates cancer-stem-like cell phenotype and increases chemosensitivity of head-and-neck squamous-cell carcinoma cells.

Cancer stem-like cells (CSCs) were reported to be linked with tumorigenesis, metastasis and resistant to chemo and radiotherapy in head and neck squamous cell carcinoma (HNSCC). In this study we investigated the role of CSCs in chemoresistance and abrogation of CSC mediated chemoresistance by combinatorial treatment with cisplatin and small molecule tankyrase inhibitor XAV-939. Two cisplatin-resistant HNSCC cells were generated by stepwise dose incremental strategy. We evaluated the chemoresistance, sphere forming capacity, extent of DNA damage and repair capacity in parental and cisplatin-resistant HNSCC cells. Furthermore, the abrogation of CSC mediated chemoresistance was evaluated in HNSCC cells with XAV-939 alone and in combination with cisplatin. It was observed that cisplatin-resistant HNSCC cell lines exhibited increase in chemoresistance, CSC phenotype and increased DNA repair capacity. We observed that combination of cisplatin and XAV-939 acts synergistically to abrogate chemoresistance by increasing DNA damage. Molecular docking study also revealed similar binding region that could contribute towards synergy predictions between cisplatin and XAV939. In conclusion, this study elucidated that combination of cisplatin and XAV-939 exerted cytotoxic and genotoxic effect to abrogate CSC mediated chemoresistance in HNSCC in synergistic manner.

A Child with Partial Trisomy 4 (q26 - qterminal) Resulting from Paternally Inherited Translocation (4:18) Associated with Multiple Congenital Anomalies and Death.

Parental balanced reciprocal translocations can result in partial aneuploidy in the offspring due to unbalanced meiotic segregation during gametogenesis. Herein, we report the phenotypic and cytogenetic characterization in a 9-day-old male child with partial trisomy of chromosome 4. Karyotyping of the proband and parents was performed along with multicolor fluorescence in situ hybridization (mFISH) of paternal chromosomes. Conventional cytogenetic analysis by karyotyping showed 47,XY,der(18),t(4;18)(q26;q22),+4 in proband, and the paternal karyotype was found as 47,XY,der(18),t(4;18)(q26;q22). mFISH analysis on paternal chromosomal preparations confirmed both region and origin of the balanced translocation. In this study, karyotyping helped us to identify both numerical and structural anomalies in the proband, and mFISH helped us to confirm our cytogenetic findings. Therefore, cytogenetic screening of both partners is recommended before pregnancy to rule out or confirm the presence of any numerical or structural anomaly in one, both, or none of the partners.

Zika virus alters DNA methylation status of genes involved in Hippo signaling pathway in human neural progenitor cells.

Aim: This study was aimed to understand if Zika virus (ZIKV) alters the DNA methylome of human neural progenitor cells (hNPCs). Materials & methods: Whole genome DNA methylation profiling was performed using human methylationEPIC array in control and ZIKV infected hNPCs. Results & conclusion: ZIKV infection altered the DNA methylation of several genes such as WWTR1 (TAZ) and RASSF1 of Hippo signaling pathway which regulates organ size during brain development, and decreased the expression of several centrosomal-related microcephaly genes, and genes involved in stemness and differentiation in human neural progenitor cells. Overall, ZIKV downregulated the Hippo signaling pathway genes which perturb the stemness and differentiation process in hNPCs, which could form the basis for ZIKV-induced microcephaly.

The role of p38 MAPK pathway in p53 compromised state and telomere mediated DNA damage response.

There is an intricate balance of DNA damage response and repair which determines the homeostasis of human genome function. p53 protein is widely known for its role in cell cycle regulation and tumor suppressor activity. In case of several cancers where function of p53 gene gets compromised either by mutation or partial inactivation, the role of p53 in response to DNA damage needs to be supplemented by another molecule or pathway. Due to sedentary lifestyle and exposure to genotoxic agents, genome is predisposed to chronic stress, which ultimately leads to unrepaired or background DNA damage. p38 MAPK signaling pathway is strongly activated in response to various environmental and cellular stresses. DNA damage response and the repair options have crucial links with chromosomal integrity. Telomere that regulates integrity of genome is protected by a six member shielding unit called shelterin complex which communicates with other pathways for functionality of telomeres. There are evidences that p38 gets activated through ATM in response to DNA damage. Dysfunctional telomere leads to activation of ATM which subsequently activates p38 suggesting a crosstalk between p38, ATM and shelterin complex. This review focuses on activation of p38 in response to genotoxic stress induced DNA damage in p53 mutated or compromised state and its possible cross talk with telomere shelterin proteins. Thus p38 may act as an important target to treat various diseases and in majority of cancers in p53 mutated state.

Telomere Biology-Insights into an Intriguing Phenomenon.

Bacteria and viruses possess circular DNA, whereas eukaryotes with typically very large DNA molecules have had to evolve into linear chromosomes to circumvent the problem of supercoiling circular DNA of that size. Consequently, such organisms possess telomeres to cap chromosome ends. Telomeres are essentially tandem repeats of any DNA sequence that are present at the ends of chromosomes. Their biology has been an enigmatic one, involving various molecules interacting dynamically in an evolutionarily well-trimmed fashion. Telomeres range from canonical hexameric repeats in most eukaryotes to unimaginably random retrotransposons, which attach to chromosome ends and reverse-transcribe to DNA in some plants and insects. Telomeres invariably associate with specialised protein complexes that envelop it, also regulating access of the ends to legitimate enzymes involved in telomere metabolism. They also transcribe into repetitive RNA which also seems to be playing significant roles in telomere maintenance. Telomeres thus form the intersection of DNA, protein, and RNA molecules acting in concert to maintain chromosome integrity. Telomere biology is emerging to appear ever more complex than previously envisaged, with the continual discovery of more molecules and interplays at the telomeres. This review also includes a section dedicated to the history of telomere biology, and intends to target the scientific audience new to the field by rendering an understanding of the phenomenon of chromosome end protection at large, with more emphasis on the biology of human telomeres. The review provides an update on the field and mentions the questions that need to be addressed.

Zinc oxide nanoparticles exhibit cytotoxicity and genotoxicity through oxidative stress responses in human lung fibroblasts and Drosophila melanogaster.

BACKGROUND: Although zinc oxide nanoparticles (ZnO NPs) have been widely used, there has been an increasing number of reports on the toxicity of ZnO NPs. However, study on the underlying mechanisms under in vivo conditions is insufficient. METHODS: In this study, we investigated the toxicological profiles of ZnO NPs in MRC5 human lung fibroblasts in vitro and in an in vivo model using the fruit fly Drosophila melanogaster. A comprehensive study was conducted to evaluate the uptake, cytotoxicity, reactive oxygen species (ROS) formation, gene expression profiling and genotoxicity induced by ZnO NPs. RESULTS: For in vitro toxicity, the results showed that there was a significant release of extracellular lactate dehydrogenase and decreased cell viability in ZnO NP-treated MRC5 lung cells, indicating cellular damage and cytotoxicity. Generation of ROS was observed to be related to significant expression of DNA Damage Inducible Transcript (DDIT3) and endoplasmic reticulum (ER) to nucleus signaling 1 (ERN1) genes, which are ER stress-related genes. Oxidative stress induced DNA damage was further verified by a significant release of DNA oxidation product, 8-hydroxydeoxyguanosine (8-OHdG), as well as by the Comet assay. For the in vivo study using the fruit fly D. melanogaster as a model, significant toxicity was observed in F1 progenies upon ingestion of ZnO NPs. ZnO NPs induced significant decrease in the egg-to-adult viability of the flies. We further showed that the decreased viability is closely associated with ROS induction by ZnO NPs. Removal of one copy of the D. melanogaster Nrf2 alleles further decreased the ZnO NPs-induced lethality due to increased production of ROS, indicating that nuclear factor E2-related factor 2 (Nrf2) plays important role in ZnO NPs-mediated ROS production. CONCLUSION: The present study suggests that ZnO NPs induced significant oxidative stress-related cytotoxicity and genotoxicity in human lung fibroblasts in vitro and in D. melanogaster in vivo. More extensive studies would be needed to verify the safety issues related to increased usage of ZnO NPs by consumers.

Trans-dichlorooxovandium (IV) complex as a novel photoinducible DNA interstrand crosslinker for cancer therapy.

Although DNA interstrand crosslinking (ICL) agents such as mitomycin C, cisplatin and psoralen serve as potent anticancer drugs, these agents are known to have dose-limiting toxic effects on normal cells. Moreover, tumor resistance to these agents has been reported. Here, we show that trans-dichlorooxovanadium (IV) complex of pyrenyl terpyridine (VDC) is a novel photoinducible DNA crosslinking agent. By a combination of in vitro and ex vivo experiments including plasmid-based assays, we find that VDC forms monoadducts on the DNA and can be activated by UV-A and visible light to generate DNA interstrand crosslinks. VDC efficiently activates Fanconi anemia (FA) pathway of DNA interstrand crosslink repair. Strikingly, photoinduction of VDC induces prolonged activation of cell cycle checkpoint and a high degree of cell death in homologous recombination (HR)/ICL repair defective cells. Moreover, VDC specifically targets cells that express pathological RAD51C mutants. These data imply that VDC can be potentially used for cancer therapy and suggest that tumors arising in patients with gene mutations in FA and HR repair pathway can be specifically targeted by a photoactivatable VDC.

Differential resistance of human embryonic stem cells and somatic cell types to hydrogen peroxide-induced genotoxicity may be dependent on innate basal intracellular ROS levels.

Previously, we demonstrated that undifferentiated human embryonic stem cells (hESC) displayed higher resistance to oxidative and genotoxic stress compared to somatic cells, but did not further probe the underlying mechanisms. Using H2O2-induced genotoxicity as a model, this study investigated whether higher resistance of hESC to oxidative and genotoxic stress could be due to lower innate basal intracellular levels of reactive oxygen species (ROS), as compared to their differentiated fibroblastic progenies (H1F) and two other somatic cell types - human embryonic palatal mesenchymal (HEPM) cells and peripheral blood lymphocytes (PBL). Comet assay demonstrated that undifferentiated hESC consistently sustained lower levels of DNA damage upon acute exposure to H2O2 for 30 min, compared to somatic cells. DCFDA and HE staining with flow cytometry showed that undifferentiated hESC had lower innate basal intracellular levels of reactive oxygen species compared to somatic cells, which could lead to their higher resistance to genotoxic stress upon acute exposure to H2O2.

Clinico-Pathological Correlation of ß-Catenin and Telomere Dysfunction in Head and Neck Squamous Cell Carcinoma Patients.

BACKGROUND: Tumorigenesis is a complex process of accumulated alteration in function of multiple genes and pathways. Wnt signalling pathway is involved in various differentiation events during embryonic development and is conserved in various species. OBJECTIVE: A multicentre collaborative initiative is undertaken to study the occurrence, prognosis and molecular mechanism of HNSCC (Head and Neck Squamous Cell Carcinoma) which is highly prevalent in eastern parts of India. From a large cohort of HNSCC tissue repository, 67 cases were selected for multi-parametric investigation. RESULTS: 67 cases showed stable ß-catenin expression. We have seen correlation, if any, of the transcription factor - ß-catenin, telomere maintenance and shelterin complex proteins - TRF2, Rap1 and hTert with respect to tumor differentiation and telomere dysfunction. Immunohistochemistry of ß-catenin protein showed stable and high expression in tumor when compared to stroma. MDSCC (Moderately Differentiated Squamous cell carcinoma) cases expressed nuclear expression of ß-catenin in invasive fronts and showed increased genomic instability. Higher frequency of Anaphase bridges was observed ranging from <3% in normal cut margin to 13% in WDSCC (Well differentiated squamous cell carcinoma) and 18% in MDSCC (Moderately differentiated Squamous cell carcinoma). There was significant decrease in telomere length in MDSCC (<4) when compared to the normal cut margin samples (<7). Quantitative Real Time-PCR confirmed a significant correlationship between stable ß-catenin expression and poor clinical and pathological outcome. CONCLUSION: The Stabilisation and accumulation of ß-catenin was significant and correlated well with de-differentiation process as well as prognosis and therapy outcome of the patients in the cohort. Expression status of molecular markers such as ß-catenin, hTert, TRF2 and RAP1 correlate significantly with the process of tumorigenesis and prognosis and may play a role in therapeutic management of Head and neck patients.

Evaluation of human embryonic stem cells and their differentiated fibroblastic progenies as cellular models for in vitro genotoxicity screening.

This study evaluated human embryonic stem cells (hESC) and their differentiated fibroblastic progenies as cellular models for genotoxicity screening. The DNA damage response of hESCs and their differentiated fibroblastic progenies were compared to a fibroblastic cell line (HEPM, CRL1486) and primary cultures of peripheral blood lymphocytes (PBL), upon exposure to Mitomycin C, gamma irradiation and H2O2. It was demonstrated that hESC-derived fibroblastic progenies (H1F) displayed significantly higher chromosomal aberrations, micronuclei formation and double strand break (DSB) formation, as compared to undifferentiated hESC upon exposure to genotoxic stress. Nevertheless, H1F cell types displayed comparable sensitivities to genotoxic challenge as HEPM and PBL, both of which are representative of somatic cell types commonly used for genotoxicity screening. Subsequently, transcriptomic and pathways analysis identified differential expression of critical genes involved in cell death and DNA damage response upon exposure to gamma irradiation. The results thus demonstrate that hESC-derived fibroblastic progenies are as sensitive as commonly-used somatic cell types for genotoxicity screening. Moreover, hESCs have additional advantages, such as their genetic normality compared to immortalized cell lines, as well as their amenability to scale-up for producing large, standardized quantities of cells for genotoxicity screening on an industrial scale, something which can never be achieved with primary cell cultures.

Toxicological profile of small airway epithelial cells exposed to gold nanoparticles.

Gold nanoparticles (AuNPs) have diverse applications in the biomedical industry such as in diagnosis, labeling, delivering and sensing. Despite their prevalent medical use, nanotoxicity induced by AuNPs is still largely unknown. We have previously shown that AuNPs could exert cytotoxic effects on lung fibroblasts. In this study, we investigated the in vitro toxicological effects of AuNPs in small airway epithelial cells (SAECs) which are the first cells of contact for inhaled NPs and compared expression of metallothionein (MT), a reactive oxygen species scavenger, in SAECs and lung fibroblasts in vitro. Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy study revealed cellular uptake of aggregates of AuNPs into the cytoplasm at the ultrastructural level. A significant increase in lipid peroxide as well as substantial DNA damage and cytotoxicity was observed in AuNP-treated cells. For MT expression, AuNPs induced down-regulation of the MT-1X isoform in SAECs, but up-regulation of the MT-1X and MT-2 A isoforms in MRC5 lung fibroblasts. The present study suggests that AuNPs could induce oxidative stress-related cytotoxicity and genotoxicity in SAECs.