Cancer chemopreventive effects of the flavonoid-rich fraction isolated from papaya seeds.

Intervention to decelerate, arrest, or reverse the process of carcinogenesis by the use of either natural or synthetic agents individually or in combination has emerged as a promising and pragmatic medical approach to reduce cancer risk. In the present study, we examined the cancer chemopreventive potential of a flavonoid-rich fraction isolated from the seeds of Carica papaya, a plant traditionally referred to as papaw. The flavonoid-enriched benzene fraction of the aqueous extract exerted its anticancer properties in vitro through cytoprotection, antioxidative and antiinflammatory mechanisms and genoprotection in response to isocyanate-induced carcinogenicity. Medium-term anticarcinogenicity and 2-stage skin papillomagenesis studies conducted in benzopyrene-induced lung carcinogenesis and 7,12-dimethyl benz(a)anthracene-mediated skin papillomagenesis mouse models further validated our in vitro observations. This is the first demonstration of chemopreventive activities of papaya seed products, however, further studies to understand the subtle targets of intracellular signaling pathways, pharmacological profile and toxicological safety of this bioactive fraction are essential to pave the way for successful clinical translation. Our study supports the inverse association between dietary flavonoid intake and cancer risk.

Cell cycle deregulation by methyl isocyanate: Implications in liver carcinogenesis.

Liver is often exposed to plethora of chemical toxins. Owing to its profound physiological role and central function in metabolism and homeostasis, pertinent succession of cell cycle in liver epithelial cells is of prime importance to maintain cellular proliferation. Although recent evidence has displayed a strong association between exposures to methyl isocyanate (MIC), one of the most toxic isocyanates, and neoplastic transformation, molecular characterization of the longitudinal effects of MIC on cell cycle regulation has never been performed. Here, we sequentially delineated the status of different proteins arbitrating the deregulation of cell cycle in liver epithelial cells treated with MIC. Our data reaffirms the oncogenic capability of MIC with elevated DNA damage response proteins pATM and γ-H2AX, deregulation of DNA damage check point genes CHK1 and CHK2, altered expression of p53 and p21 proteins involved in cell cycle arrest with perturbation in GADD-45 expression in the treated cells. Further, alterations in cyclin A, cyclin E, CDK2 levels along with overexpression of mitotic spindle checkpoints proteins Aurora A/B, centrosomal pericentrin protein, chromosomal aberrations, and loss of Pot1a was observed. Thus, MIC impacts key proteins involved in cell cycle regulation to trigger genomic instability as a possible mechanism of developmental basis of liver carcinogenesis.

Impairment of mitochondrial-nuclear cross talk in neutrophils of patients with type 2 diabetes mellitus.

Increased leukocyte apoptosis is intrinsically linked to disease patho-physiology, susceptibility to and severity of infections in type 2 diabetes mellitus (T2DM) patients. A consistent defect in neutrophil function is considered central to this increased risk for infections. Although redox imbalance is considered a potential mediator of these associated complications, detailed molecular evidence in clinical samples remains largely undetected. The study consisted of three groups (n = 50 each) of Asian Indians: early diagnosed diabetic patients, cases with late-onset diabetic complications and age and gender-matched healthy controls. We evaluated mitochondrial oxidative stress, levels of nuclear DNA damage and apoptosis in peripheral blood neutrophils isolated from T2DM patients. We observed that in both early and late diabetic subjects, the HbA1c levels in neutrophils were altered considerably with respect to healthy controls. Increased oxidative stress observed in both early and late diabetics imply the disentanglement of fine equilibrium of mitochondria-nuclear cross talk which eventually effected the augmentation of downstream nuclear γH2AX activation and caspase-3 expression. It would be overly naïve to refute the fact that mitochondrial deregulation in neutrophils perturbs immunological balance in type 2 diabetic conditions. By virtue of our data, we posit that maneuvering mitochondrial function might offer a prospective and viable method to modulate neutrophil function in T2DM. Nevertheless, similar investigations from other ethnic groups in conjunction with experimental evidences would be a preeminent need. Obviously, our study might aid to comprehend this complex interplay between mitochondrial dysfunction and neutrophil homeostasis in T2DM.

Cell-free chromatin particles released from dying cells inflict mitochondrial damage and ROS production in living cells.

Mitochondrial damage and the resultant oxidative stress are associated with neurodegenerative diseases, ageing, and cancer. However, the triggers of mitochondrial damage remain unclear. We previously reported that cell-free chromatin particles (cfChPs) released from the billions of cells that die in the body every day can readily enter healthy cells and damage their DNA. Here, we show that cfChPs isolated from the sera of healthy individuals, when applied to NIH3T3 mouse fibroblast cells, cause physical damage to mitochondrial DNA (mtDNA). cfChPs also induce ultrastructural changes, increase mitochondrial mass, alter mitochondrial shape, upregulate mitochondrial outer membrane protein translocase of the outer membrane 20, and change mitochondrial membrane potential. Furthermore, a marked increase was observed in mitochondrial superoxide (ROS) production, as detected by MitoSOX Red, and intracellular superoxide dismutase-1 activation. ROS production was also activated when a conditioned medium containing cfChPs released from hypoxia-induced dying NIH3T3 cells was applied to healthy NIH3T3 cells. ROS activation was significantly reduced when the conditioned medium was pre-treated with three different cfChP-deactivating agents: anti-histone antibody-complexed nanoparticles, DNase I, and the novel pro-oxidant combination of the nutraceuticals resveratrol and copper. Given that 1 × 109-1 × 1012 cells die in the body every day, we hypothesise that cfChPs from dying cells are the major physiological triggers for mtDNA damage and ROS production. Deactivation of cfChPs may provide a novel therapeutic approach to retard ageing and associated degenerative conditions linked to oxidative stress.

Therapeutic interventions on human breast cancer xenografts promote systemic dissemination of oncogenes.

Metastatic dissemination following successful treatment of the primary tumour remains a common cause of death. There is mounting evidence that therapeutic interventions themselves may promote development of metastatic disease. We earlier reported that cell-free chromatin particles (cfChPs) released from dying cancer cells are potentially oncogenic. Based on this observation we hypothesized that therapeutic interventions may lead to the release of cfChPs from therapy induced dying cancer cells which could be carried via the blood stream to distant organs to transform healthy cells into new cancers that would masquerade as metastasis. To test this hypothesis, we generated xenografts of MDA-MB-231 human breast cancer cells in severe combined immune-deficient mice, and using immuno-fluorescence and FISH analysis looked for cfChPs in their brain cells. We detected multiple human DNA signals representing cfChPs in nuclei of brain cells of mice which co-localized with eight human onco-proteins. No intact MDA-MB-231 cells were detected. The number of co-localizing human DNA and human c-Myc signals increased dramatically following treatment with chemotherapy, localized radiotherapy or surgery, which could be prevented by concurrent treatment with three different cfChPs deactivating agents. These results suggest that therapeutic interventions lead to the release cfChPs from therapy induced dying cancer cells carrying oncogenes and are transported via the blood stream to brain cells to potentially transform them to generate new cancers that would appear as metastases. cfChPs induced metastatic spread of cancer is preventable by concurrent treatment with agents that deactivate cfChPs.

Correction: Therapeutic interventions on human breast cancer xenografts promote systemic dissemination of oncogenes.

[This corrects the article DOI: 10.1371/journal.pone.0298042.].

Cell-free chromatin particles released from dying cancer cells activate immune checkpoints in human lymphocytes: implications for cancer therapy.

Immune checkpoint blockade is the exciting breakthrough in cancer, but how immune checkpoints are activated is unknown. We have earlier reported that cell-free chromatin particles (cfChPs) that circulate in blood of cancer patients, or those that are released locally from dying cancer cells, are readily internalized by healthy cells with biological consequences. Here we report that treatment of human lymphocytes with cfChPs isolated from sera of cancer patients led to marked activation of the immune checkpoints PD-1, CTLA-4, LAG-3, NKG2A, and TIM-3. This finding was corroborated in vivo in splenocytes of mice when cfChPs were injected intravenously. Significant upregulation of immune checkpoint was also observed when isolated lymphocytes were exposed to conditioned medium containing cfChPs released from hypoxia-induced dying HeLa cells. Immune checkpoint activation could be down-regulated by pre-treating the conditioned media with three different cfChPs deactivating agents. Down-regulation of immune checkpoints by cfChPs deactivating agents may herald a novel form of immunotherapy of cancer.

A pro-oxidant combination of resveratrol and copper down-regulates multiple biological hallmarks of ageing and neurodegeneration in mice.

Billions of cells die in the body every day, and cell-free chromatin particles (cfChPs) which are released from them enter into the extracellular compartments of the body, including into the circulation. cfChPs are known to readily enter into healthy cells to damage their DNA and activate apoptotic and inflammatory pathways. We have hypothesized that lifelong assault on healthy cells by cfChPs is the underlying cause of ageing, and that ageing could be retarded by deactivating extra-cellular cfChPs. The latter can be effected by oxygen radicals that are generated upon admixing the nutraceuticals resveratrol and copper (R-Cu). The present study investigated whether prolonged administration of R-Cu would retard biological hallmarks of ageing. C57Bl/6 mice were divided into 3 equal groups; one group was sacrificed at age 3 months, and which acted as young controls. The remaining mice were allowed to age, and at age 10 months the experimental ageing group was given R-Cu by oral gavage twice daily for further 12 months at a dose of 1 mg/kg of R and 0.1 µg/kg of Cu. The control ageing group was given water by oral gavage twice daily for 12 months. Animals of both groups were sacrificed at age 22 months. R-Cu treatment led to reduction of several biological hallmarks of ageing in brain cells which included telomere attrition, amyloid deposition, DNA damage, apoptosis, inflammation, senescence, aneuploidy and mitochondrial dysfunction. R-Cu treatment also led to significant reduction in blood levels of glucose, cholesterol and C-reactive protein. These findings suggest that cfChPs may act as global instigators of ageing and neurodegeneration, and that therapeutic use of R-Cu may help to make healthy ageing an attainable goal.

A pro-oxidant combination of resveratrol and copper down-regulates hallmarks of cancer and immune checkpoints in patients with advanced oral cancer: Results of an exploratory study (RESCU 004).

Background: Our earlier studies have shown that cell-free chromatin particles (cfChPs) that are released from dying cancer cells are readily internalised by bystander cells leading to activation of two hallmarks of cancer viz. genome instability and inflammation. These hallmarks could be down-regulated by deactivating cfChPs via medium of oxygen radicals generated upon admixing small quantities of the nutraceuticals resveratrol (R) and copper (Cu). In this exploratory study, we investigated whether oral administration of R and Cu (R-Cu) would down-regulate the hallmarks of cancer and immune checkpoints in advanced squamous cell carcinoma of oral cavity (OSCC). Patients and methods: The study comprised of 25 patients divided into 5 equal groups. Five patients acted as controls; the remaining 20 were given R-Cu in four escalating doses. The lowest dose of R-Cu was 5.6mg and 560ng respectively, and the highest dose was 500mg and 5mg respectively. An initial biopsy was taken from patients at first presentation, and a second biopsy was taken 2 weeks later on the operating table. R-Cu was administered orally twice daily in the intervening period. Confocal microscopy was performed on tumour sections after fluorescent immuno-staining with anti-DNA and anti-histone antibodies to detect presence of cfChPs in the tumour micro-environment (TME). Immunofluorescence analysis was performed for 23 biomarkers representing the 10 Hallmarks of cancer, including 5 immune checkpoints, defined by Hanahan and Weinberg. Results: Confocal microscopy detected copious presence of cfChPs in TME of OSCC, which were eradicated/deactivated following two-week treatment with R-Cu. Eradication of cfChPs from TME was associated with marked down-regulation of 21/23 biomarkers, including the five immune checkpoints. The lower two doses of R-Cu were more effective than the higher doses. No adverse effects attributable to R-Cu were observed. Conclusion: These results suggest that cfChPs released into TME from dying cancer cells are global instigators for cancer hallmarks and immune checkpoints in surviving cancer cells. The ability of R-Cu to deactivate cfChPs raises the prospect of a novel and non-toxic form of cancer treatment which sans killing of cancer cells, and instead induces healing by down-regulating cancer hallmarks and immune check-points. Clinical Trial Registration: http://ctri.nic.in/Clinicaltrials/pmaindet2.php?trialid=19801&EncHid=&userName=CTRI/2018/03/012459.

Cell-free chromatin particles released from dying host cells are global instigators of endotoxin sepsis in mice.

We have earlier reported that cell-free chromatin (cfCh) particles that are released from dying cells, or those that circulate blood, can readily enter into healthy cells, illegitimately integrate into their genomes and induce dsDNA breaks, apoptosis and intense activation of inflammatory cytokines. We hypothesized that sepsis is caused by cfCh released from dying host cells following microbial infection leading to bystander host cell apoptosis and inflammation which are perpetuated in a vicious cycle with release of more cfCh from dying host cells. To test this hypothesis we used three cfCh inactivating agents namely 1) anti-histone antibody complexed nanoparticles which inactivate cfCh by binding to histones; 2) DNase I which inactivates cfCh by degrading its DNA component, and 3) a novel pro-oxidant combination of Resveratrol and Copper which, like DNase I, inactivates cfCh by degrading its DNA component. Female C57 BL/6 mice, 6-8 weeks old, were administered a single i.p. injection of LPS at a dose of 10 mg/Kg or 20 mg/Kg with or without concurrent treatment with the above cfCh inactivating agents. Administration of cfCh inactivating agents concurrently with LPS resulted in prevention of following pathological parameters: 1) release of cfCh in extra-cellular spaces of brain, lung and heart and in circulation; 2) release of inflammatory cytokines in circulation; 3) activation of DNA damage, apoptosis and inflammation in cells of thymus, spleen and in PBMCs; 4) DNA damage, apoptosis and inflammation in cells of lung, liver, heart, brain, kidney and small intestine; 5) liver and kidney dysfunction and elevation of serum lactate; 6) coagulopathy, fibrinolysis and thrombocytopenia; 7) lethality. We conclude that cfCh that are released from dying host cells in response to bacterial endotoxin represents a global instigator of sepsis. cfCh inactivation may provide a novel approach to management of sepsis in humans.

Illegitimate and Repeated Genomic Integration of Cell-Free Chromatin in the Aetiology of Somatic Mosaicism, Ageing, Chronic Diseases and Cancer.

Emerging evidence suggests that an individual is a complex mosaic of genetically divergent cells. Post-zygotic genomes of the same individual can differ from one another in the form of single nucleotide variations, copy number variations, insertions, deletions, inversions, translocations, other structural and chromosomal variations and footprints of transposable elements. High-throughput sequencing has led to increasing detection of mosaicism in healthy individuals which is related to ageing, neuro-degenerative disorders, diabetes mellitus, cardiovascular diseases and cancer. These age-related disorders are also known to be associated with significant increase in DNA damage and inflammation. Herein, we discuss a newly described phenomenon wherein the genome is under constant assault by illegitimate integration of cell-free chromatin (cfCh) particles that are released from the billions of cells that die in the body every day. We propose that such repeated genomic integration of cfCh followed by dsDNA breaks and repair by non-homologous-end-joining as well as physical damage to chromosomes occurring throughout life may lead to somatic/chromosomal mosaicism which would increase with age. We also discuss the recent finding that genomic integration of cfCh and the accompanying DNA damage is associated with marked activation of inflammatory cytokines. Thus, the triple pathologies of somatic mosaicism, DNA/chromosomal damage and inflammation brought about by a common mechanism of genomic integration of cfCh may help to provide an unifying model for the understanding of aetiologies of the inter-related conditions of ageing, degenerative disorders and cancer.

Prevention of radiation-induced bystander effects by agents that inactivate cell-free chromatin released from irradiated dying cells.

Radiation-induced bystander effect (RIBE) is a poorly understood phenomenon wherein non-targeted cells exhibit effects of radiation. We have reported that cell-free chromatin (cfCh) particles that are released from dying cells can integrate into genomes of surrounding healthy cells to induce DNA damage and inflammation. This raised the possibility that RIBE might be induced by cfCh released from irradiated dying cells. When conditioned media from BrdU-labeled irradiated cells were passed through filters of pore size 0.22 µm and incubated with unexposed cells, BrdU-labeled cfCh particles could be seen to readily enter their nuclei to activate H2AX, active Caspase-3, NFκB, and IL-6. A direct relationship was observed with respect to activation of RIBE biomarkers and radiation dose in the range of 0.1-0 Gy. We confirmed by FISH and cytogenetic analysis that cfCh had stably integrated into chromosomes of bystander cells and had led to extensive chromosomal instability. The above RIBE effects could be abrogated when conditioned media were pre-treated with agents that inactivate cfCh, namely, anti-histone antibody complexed nanoparticles (CNPs), DNase I and a novel DNA degrading agent Resveratrol-copper (R-Cu). Lower hemi-body irradiation with γ-rays (0.1-50 Gy) led to activation of H2AX, active Caspase-3, NFκB, and IL-6 in brain cells in a dose-dependent manner. Activation of these RIBE biomarkers could be abrogated by concurrent treatment with CNPs, DNase I and R-Cu indicating that activation of RIBE was not due to radiation scatter to the brain. RIBE activation was seen even when mini-beam radiation was delivered to the umbilical region of mice wherein radiation scatter to brain was negligible and could be abrogated by cfCh inactivating agents. These results indicate that cfCh released from radiation-induced dying cells are activators of RIBE and that it can be prevented by treatment with appropriate cfCh inactivating agents.

Cell-free chromatin from dying cancer cells integrate into genomes of bystander healthy cells to induce DNA damage and inflammation.

Bystander cells of the tumor microenvironment show evidence of DNA damage and inflammation that can lead to their oncogenic transformation. Mediator(s) of cell-cell communication that brings about these pro-oncogenic pathologies has not been identified. We show here that cell-free chromatin (cfCh) released from dying cancer cells are the key mediators that trigger both DNA damage and inflammation in the surrounding healthy cells. When dying human cancer cells were cultured along with NIH3T3 mouse fibroblast cells, numerous cfCh emerged from them and rapidly entered into nuclei of bystander NIH3T3 cells to integrate into their genomes. This led to activation of H2AX and inflammatory cytokines NFκB, IL-6, TNFα and IFNγ. Genomic integration of cfCh triggered global deregulation of transcription and upregulation of pathways related to phagocytosis, DNA damage and inflammation. None of these activities were observed when living cancer cells were co-cultivated with NIH3T3 cells. However, upon intravenous injection into mice, both dead and live cells were found to be active. Living cancer cells are known to undergo extensive cell death when injected intravenously, and we observed that cfCh emerging from both types of cells integrated into genomes of cells of distant organs and induced DNA damage and inflammation. γH2AX and NFκB were frequently co-expressed in the same cells suggesting that DNA damage and inflammation are closely linked pathologies. As concurrent DNA damage and inflammation is a potent stimulus for oncogenic transformation, our results suggest that cfCh from dying cancer cells can transform cells of the microenvironment both locally and in distant organs providing a novel mechanism of tumor invasion and metastasis. The afore-described pro-oncogenic pathologies could be abrogated by concurrent treatment with chromatin neutralizing/degrading agents suggesting therapeutic possibilities.

Epigenetic dimension of oxygen radical injury in spermatogonial epithelial cells.

The present work reports a direct role of mitochondrial oxidative stress induced aberrant chromatin regulation, as a central phenomenon, to perturbed genomic integrity in the testicular milieu. Oxygen-radical injury following N-succinimidyl N-methylcarbamate treatment in mouse spermatogonial epithelial (GC-1 spg) cells induced functional derailment of mitochondrial machinery. Mitophagy resulted in marked inhibition of mitochondrial respiration and reduced mtDNA copy number. Impaired cell cycle progression along with altered H3K9me1, H4K20me3, H3, AcH3 and uH2A histone modifications were observed in the treated cells. Dense heterochromatin foci and aberrant expression of HP1α in nuclei of treated cells implied onset of senescence associated secretory phenotype mediated through nuclear accumulation of NF-κB. Neoplastic nature of daughter clones, emerged from senescent mother phenotypes was confirmed by cytogenetic instability, aberrant let-7a and let-7b miRNA expression and anchorage independent growth. Together, our results provide the first insights of redox-dependent epigenomic imbalance in spermatogonia, a previously unknown molecular paradigm.

Imbalance of mitochondrial-nuclear cross talk in isocyanate mediated pulmonary endothelial cell dysfunction.

Mechanistic investigations coupled with epidemiology, case-control, cohort and observational studies have increasingly linked isocyanate exposure (both chronic and acute) with pulmonary morbidity and mortality. Though ascribed for impairment in endothelial cell function, molecular mechanisms of these significant adverse pulmonary outcomes remains poorly understood. As preliminary studies conducted in past have failed to demonstrate a cause-effect relationship between isocyanate toxicity and compromised pulmonary endothelial cell function, we hypothesized that direct exposure to isocyanate may disrupt endothelial structural lining, resulting in cellular damage. Based on this premise, we comprehensively evaluated the molecular repercussions of methyl isocyanate (MIC) exposure on human pulmonary arterial endothelial cells (HPAE-26). We examined MIC-induced mitochondrial oxidative stress, pro-inflammatory cytokine response, oxidative DNA damage response and apoptotic index. Our results demonstrate that exposure to MIC, augment mitochondrial reactive oxygen species production, depletion in antioxidant defense enzymes, elevated pro-inflammatory cytokine response and induced endothelial cell apoptosis via affecting the balance of mitochondrial-nuclear cross talk. We herein delineate the first and direct molecular cascade of isocyanate-induced pulmonary endothelial cell dysfunction. The results of our study might portray a connective link between associated respiratory morbidities with isocyanate exposure, and indeed facilitate to discern the exposure-phenotype relationship in observed deficits of pulmonary endothelial cell function. Further, understanding of inter- and intra-cellular signaling pathways involved in isocyanate-induced endothelial damage would not only aid in biomarker identification but also provide potential new avenues to target specific therapeutic interventions.

Occult hepatitis C virus elicits mitochondrial oxidative stress in lymphocytes and triggers PI3-kinase-mediated DNA damage response.

Occult hepatitis C viral infection (OHCI) is a newly reported pathological entity associated with increased risk of developing hepatocellular carcinoma and lymphoproliferative disorders. Although hepatocytes are the primary sites of viral replication, hepatitis C virus is potentially lymphotropic, invading and propagating in cells of the immune system. Lymphocytes, the extrahepatic viral reservoirs, are differentially implicated in the occult and the active forms of the disease. This study aimed to elucidate the implications of mitochondrial oxidative stress on the immune pathophysiological mechanisms of OHCI. We herein report that OHCI induces mitochondrial oxidative stress, leading to DNA double-strand breaks and elicitation of a phosphoinositol 3-kinase-mediated cellular response in peripheral blood lymphocytes. Compared to controls, OHCI subjects showed higher accumulation of pATM, pATR, γH2AX, and p-p53, along with active recruitment of repair proteins (Mre11, Rad50, and Nbs1) and altered mitochondrial DNA content. Increased mitochondrial membrane depolarization and circulating nucleosome levels along with chromatid-type aberrations and decreased T-cell proliferative index observed in the OHCI group further indicated that this damage might lead to Bax-triggered mitochondria-mediated cellular apoptosis. Together our results provide the mechanistic underpinnings of mitochondrial dysfunction in OHCI, a previously unknown paradigm, for explaining the immune pathogenesis in a redox-dependent manner.

Role and clinical significance of lymphocyte mitochondrial dysfunction in type 2 diabetes mellitus.

Lymphocyte homeostasis in type 2 diabetes mellitus (T2DM) is associated with increased susceptibility to infections. Mitochondrial oxidative stress is implicated primarily in the immune pathophysiology of diabetes; however, the molecular underpinnings of lymphocyte mitochondrial dysfunction and ensuing downstream cellular effects are hitherto unreported. Both in early diagnosed patients and patients with late complications, we observed an inverse correlation between mitochondrial DNA content in lymphocytes and hemoglobin A1 (HbA1c) levels. This relation established for the first time might serve as a general, yet direct, predictor or indicator for mitochondrial dysfunction in T2DM. Compared with controls, nuclear DNA damage response was higher (P ≤ 0.001) in diabetic subjects with increased accumulation of phospho-ataxia-telangiectasia (ATM), γ-H2AX, along with active recruitment of repair proteins (Mre11, Rad50, and Nbs1). A higher frequency (>2%) of stable chromosomal anomalies with loss of telomere integrity was observed in cases with late complications. A significant decrease (P ≤ 0.001) in enzyme activity of complex II, III, and IV of mitochondrial respiratory chain was evident in both diabetic groups in comparison with healthy controls. Activation in the cascade of nuclear factor kappa-beta (NF-κß)-mediated feed-forward proinflammatory cytokine response was noted among T2DM subjects. Increased oxidative stress, mitochondrial membrane depolarization, activation of caspase-3, and PARP observed in diabetic groups indicated bax triggered mitochondrial mediated cellular apoptosis. Our results provide the first insights of lymphocyte mitochondrial dysfunction that might be helpful in explaining the clinical significance of immunologic perturbation observed in type 2 diabetic conditions. Our data also indicate that maneuvering through the mitochondrial function might be a viable, indirect method to modulate lymphocyte homeostasis in T2DM.

Mitochondrial oxidative stress elicits chromosomal instability after exposure to isocyanates in human kidney epithelial cells.

The role of oxidative stress is often attributed in environmental renal diseases. Isocyanates, a ubiquitous chemical group with diverse industrial applications, are known to undergo bio-transformation reactions upon accidental and occupational exposure. This study delineates the role of isocyanate-mediated mitochondrial oxidative stress in eliciting chromosomal instability in cultured human kidney epithelial cells. Cells treated with 0.005 microM concentration of methyl isocyanate displayed morphological transformation and stress-induced senescence. Along the time course, an increase in DCF fluorescence indicative of oxidative stress, depletion of superoxide dismutase (SOD) and glutathione reductase (GR) and consistent accumulation of 8-oxo-dG were noticed. Thus, endogenous oxidative stress resulted in aberrant expression of p53, p21, cyclin E and CDK2 proteins, suggestive of deregulated cell cycle, chromosomal aberrations, centromeric amplification, aneuploidy and genomic instability.