Dcf1 induces glioblastoma cells apoptosis by blocking autophagy.

BACKGROUND: Dcf1 has been demonstrated to play vital roles in many CNS diseases, it also has a destructive role on cell mitochondria in glioma cells and promotes the autophagy. Hitherto, it is unclear whether the viability of glioblastoma cells is affected by Dcf1, in particular Dcf1 possesses broad localization on different organelles, and the organelles interaction frequently implicated in cancer cells survival. METHODS: Surgically excised WHO grade IV human glioblastoma tissues were collected and cells isolated for culturing. RT-PCR and DNA sequencing assay to estimate the abundance and mutation of Dcf1. iTRAQ sequencing and bioinformatic analysis were performed. Subsequently, immunoprecipitation assay to evaluate the degradation of HistoneH2A isomers by UBA52 ubiquitylation. Transmission electron microscopy (TEM) was applied to observe the structure change of mitochondria and autophagosome. Organelle isolated assay to determine the distribution of protein. Cell cycle and apoptosis were evaluated by flow cytometric assays. RESULTS: Dcf1 was downregulated in WHO grade IV tumor without mutation, and overexpression of Dcf1 was found to significantly regulate glioblastoma cells. One hundred and seventy-six differentially expressed proteins were identified by iTRAQ sequencing. Furthermore, we confirmed that overexpression of Dcf1 destabilized the structure of the nucleosome via UBA52 ubiquitination to downregulate HistoneH2A.X but not macroH2A or HistoneH2A.Z, decreased the mitochondrial DNA copy number and inhibited the mitochondrial biogenesis, thus causing mitochondrial destruction and dysfunction in order to supply cellular energy and induce mitophagy preferentially but not apoptosis. Dcf1 also has disrupted the integrity of lysosomes to block autolysosome degradation and autophagy and to increase the release of Cathepsin B and D from lysosomes into cytosol. These proteins cleaved and activated BID to induce glioblastoma cells apoptosis. CONCLUSIONS: In this study, we demonstrated that unmutated Dcf1 expression is negatively related to the malignancy of glioblastoma, Dcf1 overexpression causes nucleosomes destabilization, mitochondria destruction and dysfunction to induce mitophagy preferentially, and block autophagy by impairing lysosomes to induce apoptosis in glioblastoma.

Sophisticated Conversations between Chromatin and Chromatin Remodelers, and Dissonances in Cancer.

The establishment and maintenance of genome packaging into chromatin contribute to define specific cellular identity and function. Dynamic regulation of chromatin organization and nucleosome positioning are critical to all DNA transactions-in particular, the regulation of gene expression-and involve the cooperative action of sequence-specific DNA-binding factors, histone modifying enzymes, and remodelers. Remodelers are molecular machines that generate various chromatin landscapes, adjust nucleosome positioning, and alter DNA accessibility by using ATP binding and hydrolysis to perform DNA translocation, which is highly regulated through sophisticated structural and functional conversations with nucleosomes. In this review, I first present the functional and structural diversity of remodelers, while emphasizing the basic mechanism of DNA translocation, the common regulatory aspects, and the hand-in-hand progressive increase in complexity of the regulatory conversations between remodelers and nucleosomes that accompanies the increase in challenges of remodeling processes. Next, I examine how, through nucleosome positioning, remodelers guide the regulation of gene expression. Finally, I explore various aspects of how alterations/mutations in remodelers introduce dissonance into the conversations between remodelers and nucleosomes, modify chromatin organization, and contribute to oncogenesis.

Nucleosomal association and altered interactome underlie the mechanism of cataract caused by the R54C mutation of αA-crystallin.

BACKGROUND: αA-crystallin plays an important role in eye lens development. Its N-terminal domain is implicated in several important biological functions. Mutations in certain conserved arginine residues in the N-terminal region of αA-crystallin lead to cataract with characteristic cytoplasmic/nuclear aggregation of the mutant protein. In this study, we attempt to gain mechanistic insights into the congenital cataract caused by the R54C mutation in human αA-crystallin. METHODS: We used several spectroscopic techniques to investigate the structure and function of the wild-type and R54CαA-crystallin. Immunoprecipitation, chromatin-enrichment followed by western blotting, immunofluorescence and cell-viability assay were performed to study the interaction partners, chromatin-association, stress-like response and cell-death caused by the mutant. RESULTS: Although R54CαA-crystallin exhibited slight changes in quaternary structure, its chaperone-like activity was comparable to that of wild-type. When expressed in lens epithelial cells, R54CαA-crystallin exhibited a speckled appearance in the nucleus rather than cytoplasmic localization. R54CαA-crystallin triggered a stress-like response, resulting in nuclear translocation of αB-crystallin, disassembly of cytoskeletal elements and activation of caspase 3, leading to apoptosis. Analysis of the "interactome" revealed an increase in interaction of the mutant protein with nucleosomal histones, and its association with chromatin. CONCLUSIONS: The study shows that alteration of "interactome" and nucleosomal association, rather than loss of chaperone-like activity, is the molecular basis of cataract caused by the R54C mutation in αA-crystallin. GENERAL SIGNIFICANCE: The study provides a novel mechanism of cataract caused by a mutant of αA-crystallin, and sheds light on the possible mechanism of stress and cell death caused by such nuclear inclusions.

The nucleosome acidic patch and H2A ubiquitination underlie mSWI/SNF recruitment in synovial sarcoma.

Interactions between chromatin-associated proteins and the histone landscape play major roles in dictating genome topology and gene expression. Cancer-specific fusion oncoproteins, which display unique chromatin localization patterns, often lack classical DNA-binding domains, presenting challenges in identifying mechanisms governing their site-specific chromatin targeting and function. Here we identify a minimal region of the human SS18-SSX fusion oncoprotein (the hallmark driver of synovial sarcoma) that mediates a direct interaction between the mSWI/SNF complex and the nucleosome acidic patch. This binding results in altered mSWI/SNF composition and nucleosome engagement, driving cancer-specific mSWI/SNF complex targeting and gene expression. Furthermore, the C-terminal region of SSX confers preferential affinity to repressed, H2AK119Ub-marked nucleosomes, underlying the selective targeting to polycomb-marked genomic regions and synovial sarcoma-specific dependency on PRC1 function. Together, our results describe a functional interplay between a key nucleosome binding hub and a histone modification that underlies the disease-specific recruitment of a major chromatin remodeling complex.

The mechanistic basis for chromatin regulation by pioneer transcription factors.

Pioneer transcription factors play a primary role in establishing competence for gene expression and initiating cellular programming and reprogramming, and their dysregulation causes severe effects on human health, such as promoting tumorigenesis. Although more than 200 transcription factors are expressed in each cell type, only a small number of transcription factors are necessary to elicit dramatic cell-fate changes in embryonic development and cell-fate conversion. Among these key transcription factors, a subset called "pioneer transcription factors" have a remarkable ability to target nucleosomal DNA, or closed chromatin, early in development, often leading to the local opening of chromatin, thereby establishing competence for gene expression. Although more key transcription factors have been identified as pioneer transcription factors, the molecular mechanisms behind their special properties are only beginning to be revealed. Understanding the pioneering mechanisms will enhance our ability to precisely control cell fate at will for research and therapeutic purposes. This article is categorized under: Biological Mechanisms > Cell Fates Biological Mechanisms > Regulatory Biology Developmental Biology > Lineages.

The role of high-mobility group protein box 1 in lung cancer.

High-mobility group protein box 1(HMGB1)is a ubiquitous highly conserved nuclear protein. Acting as a chromatin-binding factor, HMGB1 binds to DNA and plays an important role in stabilizing nucleosome formation, facilitating gene transcription, DNA repairing, inflammation, cell differentiation, and regulating the activity of steroid hormone receptors. Currently, HMGB1 is discovered to be related to development, progression, and targeted therapy of lung cancer, which makes it an attractive biomarker, and therapeutic target. This review aims to encapsulate the relationship between HMGB1 and lung cancer, suggesting that HMGB1 plays a pivotal role in initiation, development, invasion, metastasis, and prognosis of lung cancer.

Neoadjuvant volumetric modulated arc therapy in rectal cancer and the correlation of pathological response with diffusion-weighted MRI and apoptotic markers.

PURPOSE: In this prospective observational study, we aimed to report the applicability and tolerability of neoadjuvant volumetric modulated arc therapy with simultaneous integrated boost (SIB-VMAT) and concurrent chemotherapy in patients with locally advanced rectal cancer (LARC), and to evaluate the correlation of pathological response with apparent diffusion coefficient (ADC) measurements on diffusion-weighted magnetic resonance imaging (DW-MRI) and apoptotic markers. METHODS: The study enrolled 30 patients with T3 to T4 and/or N+ rectal cancer who preoperatively received SIB-VMAT and concurrent chemotherapy. Before and after the neoadjuvant treatment, apoptotic markers including the nucleosomes and cell-free DNA fragments in the serum samples were examined; DNA integrity was assessed by amplifying the ACTB gene; and the ADC measurements on the DW-MRI were analyzed. RESULTS: No patients had acute or chronic grade III-IV toxicity. Pathologic complete response (pCR) was achieved in 8 patients (27%), while in 10 patients (33%) near-complete pathological response was obtained. Posttreatment ADC was significantly higher in patients with pCR compared with the others (1.28 vs. 1.10, p = 0.017). ROC curve analysis showed that posttreatment ADC values had a sensitivity of 75% and a specificity of 77.3% for distinguishing the patients with pCR from other responders. On the other hand, posttreatment DNA integrity values were revealed lower than the pretreatment values (p = 0.36). Also, the results revealed an insignificant increase in the posttreatment serum level of nucleosomes (p = 0.72). CONCLUSIONS: Neoadjuvant SIB-VMAT with concurrent chemotherapy was proved to be a feasible treatment regimen in LARC with tolerable side effects, and improved local control rate and pCR rate.

Mechanisms of Ubiquitin-Nucleosome Recognition and Regulation of 53BP1 Chromatin Recruitment by RNF168/169 and RAD18.

The protein 53BP1 plays a central regulatory role in DNA double-strand break repair. 53BP1 relocates to chromatin by recognizing RNF168-mediated mono-ubiquitylation of histone H2A Lys15 in the nucleosome core particle dimethylated at histone H4 Lys20 (NCP-ubme). 53BP1 relocation is terminated by ubiquitin ligases RNF169 and RAD18 via unknown mechanisms. Using nuclear magnetic resonance (NMR) spectroscopy and biochemistry, we show that RNF169 bridges ubiquitin and histone surfaces, stabilizing a pre-existing ubiquitin orientation in NCP-ubme to form a high-affinity complex. This conformational selection mechanism contrasts with the low-affinity binding mode of 53BP1, and it ensures 53BP1 displacement by RNF169 from NCP-ubme. We also show that RAD18 binds tightly to NCP-ubme through a ubiquitin-binding domain that contacts ubiquitin and nucleosome surfaces accessed by 53BP1. Our work uncovers diverse ubiquitin recognition mechanisms in the nucleosome, explaining how RNF168, RNF169, and RAD18 regulate 53BP1 chromatin recruitment and how specificity can be achieved in the recognition of a ubiquitin-modified substrate.

Evidence of Netosis in Septic Shock-Induced Disseminated Intravascular Coagulation.

INTRODUCTION: Neutrophils extracellular traps (NETs) have recently emerged as a new potential link between inflammation, immunity, and thrombosis and could play a key role in septic shock-induced disseminated intravascular coagulation (DIC) pathogenesis. The objective of our study was to investigate a potential link between NETosis and septic shock-induced DIC. METHODS: Twenty patients with septic shock (10 without and 10 with DIC according to JAAM 2006 score) were prospectively included in our study. Vascular cell activation was assessed by microparticle (MP) measurement. NETosis was investigated at days 1, 3, and 7 using two different approaches: probing and measurement of neutrophil DNA decompaction by neutrophil-side fluorescence light (NEUT-SFL) as recorded by an automated blood cell cytometer and the assessment of nucleosomes and NETs (DNA-bound myeloperoxidase, DNA-MPO). RESULTS: Endothelial-derived CD105-MPs, leucocyte-derived CD11a-MPs/leucocyte, and neutrophil-derived CD66b-MPs/neutrophil count ratios significantly increased in DIC compared with non-DIC patients, indicating on-going cell activation (P <0.05). NEUT-SFL, indicating DNA decompaction, was significantly higher in DIC patients. Circulating nucleosomes and DNA-MPO were increased in DIC patients (P <0.05). There were significant correlations between: nucleosomes and NETs (r = 0.397, P = 0.004), NEUT-SFL and nucleosomes (r = 0.243, P = 0.032), NEUT-SFL and DNA-MPO (r = 0.266, P = 0.024). CONCLUSION: NEUT-SFL, NETs, and elevated nucleosome concentrations were all correlated to DIC (P <0.05). We have shown that NETosis is significantly correlated to septic shock-induced DIC.

Total triterpenoids from Ganoderma Lucidum suppresses prostate cancer cell growth by inducing growth arrest and apoptosis.

In this study, one immortalized human normal prostatic epithelial cell line (BPH) and four human prostate cancer cell lines (LNCaP, 22Rv1, PC-3, and DU-145) were treated with Ganoderma Lucidum triterpenoids (GLT) at different doses and for different time periods. Cell viability, apoptosis, and cell cycle were analyzed using flow cytometry and chemical assays. Gene expression and binding to DNA were assessed using real-time PCR and Western blotting. It was found that GLT dose-dependently inhibited prostate cancer cell growth through induction of apoptosis and cell cycle arrest at G1 phase. GLT-induced apoptosis was due to activation of Caspases-9 and -3 and turning on the downstream apoptotic events. GLT-induced cell cycle arrest (mainly G1 arrest) was due to up-regulation of p21 expression at the early time and down-regulation of cyclin-dependent kinase 4 (CDK4) and E2F1 expression at the late time. These findings demonstrate that GLT suppresses prostate cancer cell growth by inducing growth arrest and apoptosis, which might suggest that GLT or Ganoderma Lucidum could be used as a potential therapeutic drug for prostate cancer.

Co-Positivity for Anti-dsDNA, -Nucleosome and -Histone Antibodies in Lupus Nephritis Is Indicative of High Serum Levels and Severe Nephropathy.

OBJECTIVE: To characterize the significance of correlated autoantibodies in systemic lupus erythematosus (SLE) and its complication lupus nephritis (LN) in a large cohort of patients. METHODS: Clinical data were statistically analyzed in 1699 SLE patients with or without nephritis who were diagnosed and treated during 2002-2013 in the northeast region of China. Reactivity to a list of 16 autoantibodies was detected by the serum test Euroline ANA profile (IgG). Serum titers of the anti-nucleosome autoantibodies were measured by ELISA assays. Kidney biopsies were examined by pathologists. Immune complex deposition was identified by immunohistochemistry stain. RESULTS: Simultaneous positivity of anti-dsDNA, -nucleosome and -histone antibodies (3-pos) was prevalent in SLE patients with LN compared to Non-renal SLE patients (41% vs 11%, p< 0.001). Significant correlations were found between any two of the above three anti-nucleosome antibodies in LN patients. In comparison to non-3-pos cohorts, 3-pos patients with LN had significantly higher serum levels of the three antibodies and more active disease; was associated with type IV disease; suffered from more severe renal damages; received more intensive treatment and had worse disease outcome. The serum levels of these three autoantibodies in 3-pos LN patients were significantly decreased when they underwent clinical recovery. CONCLUSIONS: Simultaneous reactivity to anti-dsDNA, -nucleosome and -histone antibodies by Euroline ANA profile (IgG) may indicate severe nephropathy in patients with SLE.

[Nucleosome fracton of extracellular dna as the index of apoptosis].

Review is devoted to the analysis of changes of the extracellular DNA (excDNA) in pathological conditions involving the process of apoptosis, and the possibility of using of excDNA in the diagnosis and evaluation of course of various diseases. Apoptosis is the main mechanism of the appearance of the DNA in the circulation. ExcDNA found in the norm, its function is considered to be the part of the immune response. The excDNA content increases substantially during the induction of apoptosis. Dynamics of increase of excDNA content in stroke allows to diagnose the form of stroke and massiveness of destruction of brain tissue. Reduced content of excDNA is associated with the inhibition of apoptosis, it was shown that under such conditions there is a change of composition of excDNA. Investigation of excDNA character changes in the progression and treatment of cancer substantiates the possibility of early assessment the effectiveness of treatment. It is experimentally shown the immunosuppressive action of excDNA of tumor and its transforming effect on the cells. Ionizing radiation is an examples that demonstrated the association of induction of apoptosis and the release of excDNA. It is characterize some of the genome sequences of excDNA. Created on the basis of excDNA study tests of minimally invasive diagnostics are potentially useful in oncology and other areas of medicine. The study of tandem repeats, which are absent in the assembled genome, but there is a part of excDNA, will create tests for the diagnosis of cancer in the early stages.

SETD2 loss-of-function promotes renal cancer branched evolution through replication stress and impaired DNA repair.

Defining mechanisms that generate intratumour heterogeneity and branched evolution may inspire novel therapeutic approaches to limit tumour diversity and adaptation. SETD2 (Su(var), Enhancer of zeste, Trithorax-domain containing 2) trimethylates histone-3 lysine-36 (H3K36me3) at sites of active transcription and is mutated in diverse tumour types, including clear cell renal carcinomas (ccRCCs). Distinct SETD2 mutations have been identified in spatially separated regions in ccRCC, indicative of intratumour heterogeneity. In this study, we have addressed the consequences of SETD2 loss-of-function through an integrated bioinformatics and functional genomics approach. We find that bi-allelic SETD2 aberrations are not associated with microsatellite instability in ccRCC. SETD2 depletion in ccRCC cells revealed aberrant and reduced nucleosome compaction and chromatin association of the key replication proteins minichromosome maintenance complex component (MCM7) and DNA polymerase δ hindering replication fork progression, and failure to load lens epithelium-derived growth factor and the Rad51 homologous recombination repair factor at DNA breaks. Consistent with these data, we observe chromosomal breakpoint locations are biased away from H3K36me3 sites in SETD2 wild-type ccRCCs relative to tumours with bi-allelic SETD2 aberrations and that H3K36me3-negative ccRCCs display elevated DNA damage in vivo. These data suggest a role for SETD2 in maintaining genome integrity through nucleosome stabilization, suppression of replication stress and the coordination of DNA repair.

Fresh-frozen plasma resuscitation after traumatic brain injury and shock attenuates extracellular nucleosome levels and deoxyribonuclease 1 depletion.

INTRODUCTION: Traumatic brain injury and shock are among the leading causes of trauma-related mortality. We have previously shown that fresh-frozen plasma (FFP) resuscitation reduces the size of brain lesion and associated swelling compared with crystalloids. We hypothesized that this effect would be associated with an attenuation of circulating nucleosome levels, a biomarker of injury with cytotoxic potential, through reconstitution of circulating deoxyribonuclease-1 (DNAse1), an enzyme identified as critical in nucleosome clearance from the circulation. METHODS: Twelve swine underwent a protocol of traumatic brain injury followed by 40% volume-controlled hemorrhage. Animals were left in shock (mean arterial pressure of 35 mmHg) for 2 hours before they were resuscitated with normal saline (NS) or FFP. Circulating levels of nucleosomes and DNAse1 were measured whereas extracellular nucleosomes were quantified on brain histology. Lesion size and brain swelling were also quantified. RESULTS: Nucleosome levels were significantly greater in the NS group 6 hours after resuscitation (0.32 mU vs 0.15 mU, P = .030) whereas DNAse1 levels were substantially greater in the FFP group (9.82 ng/mL vs 4.54 ng/mL, P = .010). Circulating nucleosomes levels correlated with lesion size (rho = 0.79, P = .002) as well as brain swelling (rho = 0.89, P < .001) whereas DNAse1 levels correlated with brain swelling (rho = -0.61, P = .036) but not lesion size (rho = -0.47, P = .124). Brain staining revealed nucleosome extracellularization in both groups, but this appeared more frequent in the NS-resuscitated animals. CONCLUSION: Our results show that resuscitation with FFP attenuates circulating nucleosome levels and prevents DNAse1 depletion. These factors may play a role in the neuroprotective effects observed during early resuscitation with FFP.

Circulating nucleosomes and immunogenic cell death markers HMGB1, sRAGE and DNAse in patients with advanced pancreatic cancer undergoing chemotherapy.

Serum biomarkers are urgently needed for patient stratification and efficient treatment monitoring in pancreatic cancer (PC). Within a prospective diagnostic observation study, blood samples were obtained from 78 patients with advanced PC before and weekly during the course of palliative chemotherapy. Circulating nucleosomes and immunogenic cell death markers, high-mobility group box 1 (HMGB1), soluble receptors of advanced glycation end products (sRAGE) and DNAse activity, were measured by enzyme-linked immunosorbent assay and correlated with results of radiological staging after 2 months of treatment, with time to progression (TTP) and overall survival (OS). Median TTP and OS of PC patients were 3.9 and 7.7 months, respectively. Pretherapeutic baseline biomarker levels did not correlate with objective response; however, nucleosome levels on day (d) 28 were higher (p = 0.048) and sRAGE levels at time of staging (d56) were lower in progressive patients (p = 0.046). Concerning estimation of prognosis, high nucleosome levels (d7, d14, d21 and d56), low sRAGE levels (d56) and DNAse activity courses (d0-d7) correlated with TTP, whereas high nucleosomes (d7, d14 and d56), high HMGB1 (d21 and d56) and DNAse (d0-d7) were associated with OS. After adjustment to Karnofsky performance score, nucleosomes and HMGB1 (both d56) and DNAse (d0-d7) remained independent prognostic factors. Thus, courses of circulating nucleosomes and immunogenic cell death markers HMGB1 and sRAGE show prognostic relevance in PC patients undergoing chemotherapy.

The relationship between severity of the disease and circulating nucleosomes in psoriasis patients.

Psoriasis was initially considered to represent a disease of abnormal epidermal keratinocyte proliferation. Proliferation of keratinocytes is restricted by apoptotic cell death to maintain a constant thickness of epidermis. Nucleosomes are mainly released by apoptotic cells. Tumor necrosis factor-α (TNF-α) is an important factor affecting the apoptosis. In the present study, the relationship between TNF-α, nucleosome and the Psoriasis Area and Severity Index (PASI) score was investigated. The patients were divided according to PASI score into three groups (mild, moderately, severe). Serum TNF-α and nucleosome levels were measured using Enzyme-linked immunosorbent assay (ELISA) method. Our findings show a correct relationship between PASI scores and TNF-α and an inverse relationship between nucleosome and PASI score. According to the results obtained from the study, we believe that serum nucleosome levels can be used as a new indicator in follow-up of patients with psoriasis and monitoring of the effectiveness of drugs which used in the treatment of psoriasis.

Quercetin induces cytochrome-c release and ROS accumulation to promote apoptosis and arrest the cell cycle in G2/M, in cervical carcinoma: signal cascade and drug-DNA interaction.

OBJECTIVES: Small aromatic compounds like flavonoids can intercalate with DNA molecules bringing about conformational changes leading to reduced replication and transcription. Here, we have examined one dietary flavonoid, quercetin (found in many fruit and vegetables), for possible anti-cancer effects, on HeLa cells originally derived from a case of human cervical cancer. MATERIAL AND METHODS: By circular dichroism spectroscopy we tested whether quercetin effectively interacted with DNA to bring about conformational changes that would strongly inhibit proliferation and migration of the HeLa cells. Cytotoxic effects of quercetin on cancer/normal cells, if any, were determined by MTT assay and such depolarization of mitochondrial membrane potential, as a consequence of quercetin treatment, and accumulation of reactive oxygen species (ROS) also were studied, by FACS analysis and expression profiles of different anti- and pro-apoptotic genes and their products were determined. RESULTS: Quercetin intercalated with calf thymus cell DNA and HeLa cell DNA and inhibition of anti-apoptotic AKT and Bcl-2 expression were observed. Levels of mitochondrial cytochrome-c were elevated and depolarization of mitochondrial membrane potential occurred with increase of ROS; upregulation of expression of p53 and caspase-3 activity were also noted. These alterations in signalling proteins and externalization of phosphotidyl serine residues were involved with initiation of apoptosis. Reduced AKT expression suggested reduction in cell proliferation and metastasis potential, with arrest of the cell cycle at G2/M. CONCLUSION: Quercetin would have potential for use in cervical cancer chemotherapy.

Abnormalities of apoptosis of the thyroid gland cells from extratumoral microfollicular tissue.

AIM: The aim of this study was to evaluate the frequency of existence of thyroid extratumoral normo- and microfollicular tissue in patients with thyroid carcinoma and peculiarities of apoptosis in mentioned tissue. MATERIALS AND METHODS: Using samples of normo- and microfollicular thyroid tissue it was determined the content of fragmented DNA and intensity of stimulated internucleosomal DNA fragmentation; activities of caspase-3 and cysteine lysosomal cathepsins. RESULTS: It was found that normofollicular tissue is observed more often in patients with nodal euthyroid goiter but microfollicular tissue is more common for patients with carcinoma. Extratumoral microfollicular tissue was found in the thyroid of patients above 50 years old mostly, and more rarely in young ones. The fragmented DNA concentration in microfollicular tissue was lower by a factor of 3.5 and intensity of stimulated internucleosomal DNA fragmentation was also decreased. Activity both of cathepsin B in lisosomes and caspase-3 in lysates of such tissue was also decreased. CONCLUSIONS: The decrease of intensity of spontaneous apoptosis and the absence of its modulation/induction following proapoptotic factors in extratumoral microfollicular thyroid tissue may be considered as a respond of the thyroid gland tissue to an existence of carcinoma.