PubMed Health⌕ Search

Biomedical subjects

A V Gudkov

Publications and source records attributed to A V Gudkov.

At least 19 recordsLinked to original sources
PubMed2006

Downregulation of topoisomerase IIbeta in myeloid leukemia cell lines leads to activation of apoptosis following all-trans retinoic acid-induced differentiation/growth arrest.

Among the topoisomerase (topo) II isozymes (alpha and beta), topo IIbeta has been suggested to regulate differentiation. In this study, we examined the role of topo IIbeta in all-trans retinoic acid (ATRA)-induced differentiation of myeloid leukemia cell lines. Inhibition of topo IIbeta activity or downregulation of protein expression enhanced ATRA-induced differentiation/growth arrest and apoptosis. ATRA-induced apoptosis in topo IIbeta-deficient cells involved activation of the caspase cascade and was rescued by ectopic expression of topo IIbeta. Gene expression profiling led to the identification of peroxiredoxin 2 (PRDX2) as a candidate gene that was downregulated in topo IIbeta-deficient cells. Reduced expression of PRDX2 validated at the mRNA and protein level, in topo IIbeta-deficient cells correlated with increased accumulation of reactive oxygen species (ROS) following ATRA-induced differentiation. Overexpression of PRDX2 in topo IIbeta-deficient cells led to reduced accumulation of ROS and partially reversed ATRA-induced apoptosis. These results support a role for topo IIbeta in survival of ATRA-differentiated myeloid leukemia cells. Reduced expression of topo IIbeta induces apoptosis in part by impairing the anti-oxidant capacity of the cell owing to downregulation of PRDX2. Thus, suppression of topo IIbeta and/or PRDX2 levels in myeloid leukemia cells provides a novel approach for improving ATRA-based differentiation therapy.

Antineoplastic Agents↗
PubMed2006

Targeted disruption of the mouse ing1 locus results in reduced body size, hypersensitivity to radiation and elevated incidence of lymphomas.

Ing1 belongs to the family of evolutionary conserved genes encoding nuclear PHD finger-containing proteins implicated in a variety of processes, including tumorigenesis, replicative senescence, excision repair and response to genotoxic stress. We have generated mice deficient in all the isoforms of Ing1 by targeted disruption of the exon that is common for all ing1 transcripts. Embryonic fibroblasts from ing1-knockout mice were similar to the wild-type cells in their growth characteristics, replicative lifespan in culture, p53 induction and sensitivity to various cytotoxic treatments with minor alterations in cell cycle distribution in response to genotoxic stress. ing1-deficient animals are characterized by reduced size with no obvious morphological, physiological or behavioral abnormalities, indicating that ing1 function is dispensable for the viability of mice under normal physiological conditions. Loss of ing1 was associated with earlier onset and higher incidence of lymphomas. Consistent with the possible involvement of Ing1 in DNA repair, ing1-deficient mice were more sensitive to total body gamma radiation. Our observations are well in line with the suggested role of ing1 as a candidate tumor suppressor gene involved in control of DNA damage response.

Abnormalities, Multiple↗
PubMed2006

[Heat shock proteins of freshwater protists and their involvement in adaptation to changes in the environmental salinity].

Changes in the level of heat shock proteins (HSP) in cells of freshwater protists, amoebae Amoeba proteus and ciliates Paramecium jenningsi, in response to changes in the environmental salinity were investigated. Changes in salinity levels were considered as a stress factor. The immunoblotting method revealed a polypeptide antigen cross-reacting with antibodies against bovine HSP70 in total protein extracts of both intact cells and cells subjected to salinity stress. The same polypeptide antigen was revealed in A. proteus cells subjected to heat shock. Therefore, it may be supposed that the polypeptide revealed after salinity shock is a heat shock protein related to the vertebrate HSP70. Under the impact of stress factor, well acclimated protists mostly spend their own previously accumulated HSP70. A conclusion is made that freshwater protists, living under conditions of increased salinity, appear to be preadapted to changes in environmental factors.

Adaptation, Physiological↗
PubMed2006

[Heat shock protein of HSP70 family revealed in some contemporary freshwater Amoebae and in Acanthamoeba sp. from cysts isolated from permafrost samples].

A heat shock protein of HSP70 family was revealed for the first time in trophozoites of Acanthamoeba sp. (strain Am8) excysted from cysts previously isolated from samples of permafrost aging 30,000-35,000 years. The constitutive level of this HSP, shown by immunnoblotting in unstressed trophozoites of the ancient acanthamoebae, much surpassed that in unstressed cells of the three examined species of contemporary freshwater amebae of the genus Amoeba.

Acanthamoeba↗
PubMed2005

[Light and electron microscopic investigation of Pelomyxa prima (Gruber, 1884) (Peloflagellatea, Pelobiontida)].

Cell organization of a multinuclear pelobiont Pelomyxa prima has been studied at the light and electron microscopic levels. Motile individuals demonstrate a characteristic drop-like or pyriform shape and reach 550 microkm in length. The cell cover is represented by a well-developed, morphologically differentiated glycocalyx 80-100 nm thick. The cytoplasm contains many structural vacuoles. The nuclei are of vertical type, numbering up to several nuclei in large individuals. Numerous cytoplasmic microtubules are associated with the external membrane of the nuclear envelope. Separate non-motile flagella are distributed throughout the cell surface, being more numerous in the posterior body end and uroidal zone of the protist. Basal bodies of the flagella are extremely long, being deeply immersed into the cytoplasm. These bodies are surrounded by a muff of electron-dense material, with numerous microtubules radiating from it. A compact bundle of microtubules starts from the base of a basal body axially into the cytoplasm. Besides, a band-like lateral microtubular rootlet is present. The number of microtubules in the axoneme of undulipodia is unstable. Neither mitochondria, nor Golgi complex were found. Two species of bacterial endocytobionts are present in the cytoplasm in considerable numbers.

Amoeba↗
PubMed2001

The Bloom syndrome protein interacts and cooperates with p53 in regulation of transcription and cell growth control.

Bloom syndrome is an autosomal recessive disorder associated with mutations in BLM gene encoding protein that belongs to the family of DNA helicases. It is characterized by predisposition to cancer, immunodeficiency, high sensitivity to UV and genomic instability of somatic cells. Here we show physical and functional cooperation between BLM and p53 proteins. Ectopic expression of BLM causes anti-proliferative effect in p53 wild type, but not in p53-deficient cells; p53-mediated transactivation is attenuated in primary fibroblasts from Bloom syndrome patients. BLM and p53 proteins physically interact in the cells as demonstrated in yeast and mammalian two-hybrid systems; interaction sites are mapped to 237-272 aa residues of BML and 285-340 aa of p53. Ectopic expression of the fragment of wild type BML containing p53-interactive domain suppresses p53-mediated transcription and interferes with p53-mediated growth inhibition. These observations indicate that BLM might be an important component of p53 function and suggest that Bloom Syndrome phenotype may in part be the result of the deregulation of the p53 tumor suppressor pathway.

Adenosine Triphosphatases↗
PubMed2001

Small molecules that dramatically alter multidrug resistance phenotype by modulating the substrate specificity of P-glycoprotein.

By screening a chemical library for the compounds protecting cells from adriamycin (Adr), a series of small molecules was isolated that interfered with the accumulation of Adr in mouse fibroblasts by enhancing efflux of the drug. Isolated compounds also stimulated efflux of Rhodamine 123 (Rho-123), another substrate of multidrug transporters. Stimulation of drug efflux was detectable in the cells expressing P-glycoprotein (P-gp), but not in their P-gp-negative variants, and was completely reversible by the P-gp inhibitors. A dramatic stimulation of P-gp activity against Adr and Rho-123 by the identified compounds was accompanied by suppression of P-gp-mediated efflux of other substrates, such as Taxol (paclitaxel) or Hoechst 33342, indicating that they act as modulators of substrate specificity of P-gp. Consistently, P-gp modulators dramatically altered the pattern of cross-resistance of P-gp-expressing cells to different P-gp substrates: an increase in resistance to Adr, daunorubicin, and etoposide was accompanied by cell sensitization to Vinca alkaloids, gramicidin D, and Taxol with no effect on cell sensitivity to colchicine, actinomycin D, puromycin, and colcemid, as well as to several non-P-gp substrates. The relative effect of P-gp modulators against different substrates varied among the isolated compounds that can be used as fine tools for analyzing mechanisms of drug selectivity of P-gp. These results raise the possibility of a rational control over cell sensitivity to drugs and toxins through modulation of P-gp activity by small molecules.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Chemoprotection from p53-dependent apoptosis: potential clinical applications of the p53 inhibitors.

The p53 tumor suppressor pathway is a key mediator of stress response that protects the organism from accumulating genetically altered and potentially cancerous cells by inducing growth arrest or apoptosis in damaged cells. However, under certain stressful conditions, p53 activity can result in massive apoptosis in sensitive tissues, leading to severe pathological consequences for the organism. One such situation is anticancer therapy that is often associated with general genotoxic stress, leading to p53-dependent apoptosis in the epithelia of the digestive tract and in the hematopoietic system. A chemical inhibitor of p53, capable of suppressing p53-mediated apoptosis, was shown to protect mice from lethal doses of gamma-radiation, making pharmacological suppression of p53 a perspective therapeutic approach to reduce the side-effects of cancer treatment. There are other situations, besides anti-cancer therapy, when humans are exposed to stressful conditions known to involve p53 activation, which, in extreme cases, could result in the development of life-threatening diseases. Here we review the experimental evidence on the role of p53 in tissue injuries associated with hypoxia (heart and brain ischemias) and hyperthermia (fever and burns), comparing these pathologies with the consequences of genotoxic stress of cancer treatment. The accumulated information points to the involvement of p53 in the generation of the pathological outcome of the above stresses, making them potential targets for the therapeutic application of p53 inhibitors.

Animals↗
PubMed2001

Functional analysis and intracellular localization of p53 modified by SUMO-1.

p53 tumor suppressor is a subject of several post-translational modifications, including phosphorylation, ubiquitination and acetylation, which regulate p53 function. A new covalent modification of p53 at lysine 386 by SUMO-1 was recently identified. To elucidate the function of sumoylated p53, we compared the properties of wild type p53 and sumoylation-deficient p53 mutant, K386R. No differences were found between wild type p53 and K386R mutant of p53 in transactivation or growth suppression assays. Moreover, overexpression of SUMO-1 has no effect on p53-regulated transcription. Biochemical fractionation showed that sumoylated p53 is localized in the nucleus and is tightly bound to chromatin structures. p53 and SUMO-1 co-localized in PML nuclear bodies in 293 cells and the nucleoli in MCF7 and HT1080 cells. However, sumoylation-deficient p53 mutant showed a similar pattern of intranuclear localization, suggesting that SUMO-1 does not target p53 to subnuclear structures. These data indicate that SUMO-1 modification of p53 at lysine 386 may not be essential for p53's cellular localization, transcriptional activation, or growth regulation.

Amino Acid Sequence↗
PubMed2001

Taxol-induced apoptosis depends on MAP kinase pathways (ERK and p38) and is independent of p53.

The anti-cancer agent paclitaxel (Taxol) stabilizes microtubules leading to G2/M cell cycle arrest and apoptotic cell death. In order to analyse the molecular mechanisms of Taxol-induced cytotoxicity, we studied the involvement of mitogen-activated protein kinases (MAPK) ERK and p38 as well as the p53 pathways in Taxol-induced apoptosis. The human breast carcinoma cell line MCF7 and its derivatives, MCF7/HER-2 and MDD2, were used in the study. We found that Taxol treatment strongly activated ERK, p38 MAP kinase and p53 in MAP kinase MCF7 cells prior to apoptosis. PD98059 or SB203580, specific inhibitors of ERK and p38 kinase activities, significantly decreased apoptosis, leaving the surviving cells arrested in G2/M. These inhibitors did not significantly affect Taxol-induced alterations in the cell cycle regulatory proteins Rb, p53, p21/Waf1 and Cdk-2. In addition, inactivation of p53 did not affect cellular sensitivity to Taxol killing. However, cells with inactivated p53, unlike cells harboring wild type p53, failed to arrest in G2/M after treatment with Taxol and continued to divide or go into apoptosis. Our data show that both ERK and p38 MAP kinase cascades are essential for apoptotic response to Taxol-induced cellular killing and are independent of p53 activity. However, p53 may serve as a survival factor in breast carcinoma cells treated with Taxol by blocking cells in G2/M phase of the cell cycle.

Animals↗
PubMed2001

p53 Involvement in the control of murine hair follicle regression.

p53 is a transcription factor mediating a variety of biological responses including apoptotic cell death. p53 was recently shown to control apoptosis in the hair follicle induced by ionizing radiation and chemotherapy, but its role in the apoptosis-driven physiological hair follicle regression (catagen) remains to be elucidated. Here, we show that p53 protein is strongly expressed and co-localized with apoptotic markers in the regressing hair follicle compartments during catagen. In contrast to wild-type mice, p53 knockout mice show significant retardation of catagen accompanied by significant decrease in the number of apoptotic cells in the hair matrix. Furthermore, p53 null hair follicles are characterized by alterations in the expression of markers that are encoded by p53 target genes and are implicated in the control of catagen (Bax, Bcl-2, insulin-like growth factor binding protein-3). These data suggest that p53 is involved in the control of apoptosis in the hair follicle during physiological regression and imply that p53 antagonists may be useful for the management of hair growth disorders characterized by premature entry into catagen, such as androgenetic alopecia, alopecia areata, and telogen effluvium.

Animals↗
PubMed2001

Poliovirus protein 3A inhibits tumor necrosis factor (TNF)-induced apoptosis by eliminating the TNF receptor from the cell surface.

Viral infections often trigger host defensive reactions by activating intrinsic (intracellular) and extrinsic (receptor-mediated) apoptotic pathways. Poliovirus is known to encode an antiapoptotic function(s) suppressing the intrinsic pathway. Here, the effect of poliovirus nonstructural proteins on cell sensitivity to tumor necrosis factor (TNF)-induced (i.e., receptor-mediated) apoptosis was studied. This sensitivity is dramatically enhanced by the viral proteinase 2A, due, most likely, to inhibition of cellular translation. On the other hand, cells expressing poliovirus noncapsid proteins 3A and 2B exhibit strong TNF resistance. Expression of 3A neutralizes the proapoptotic activity of 2A and results in a specific suppression of TNF signaling, including the lack of activation of NF-kappaB, due to elimination of the TNF receptor from the cell surface. In agreement with this, poliovirus infection results in a dramatic decrease in TNF receptor abundance on the surfaces of infected cells as early as 4 h postinfection. Poliovirus proteins that confer resistance to TNF interfere with endoplasmic reticulum-Golgi protein trafficking, and their effect on TNF signaling can be imitated by brefeldin A, suggesting that the mechanism of poliovirus-mediated resistance to TNF is a result of aberrant TNF receptor trafficking.

Animals↗
PubMed2000

Differential association of products of alternative transcripts of the candidate tumor suppressor ING1 with the mSin3/HDAC1 transcriptional corepressor complex.

The candidate tumor suppressor ING1 was identified in a genetic screen aimed at isolation of human genes whose expression is suppressed in cancer cells. It may function as a negative growth regulator in the p53 signal transduction pathway. However, its molecular mechanism is not clear. The ING1 locus encodes alternative transcripts of p47(ING1a), p33(ING1b), and p24(ING1c). Here we report differential association of protein products of ING1 with the mSin3 transcriptional corepressor complex. p33(ING1b) associates with Sin3, SAP30, HDAC1, RbAp48, and other proteins, to form large protein complexes, whereas p24(ING1c) does not. The ING1 immune complexes are active in deacetylating core histones in vitro, and p33(ING1b) is functionally associated with HDAC1-mediated transcriptional repression in transfected cells. Our data provide basis for a p33(ING1b)-specific molecular mechanism for the function of the ING1 locus.

3T3 Cells↗
PubMed2000

p53 is essential for chemotherapy-induced hair loss.

Anticancer drugs stimulate apoptosis in the hair follicles (HF) and cause hair loss, the most common side effect of chemotherapy. In a mouse model for chemotherapy-induced hair loss, we demonstrate that p53 is essential for this process: in contrast to wild-type mice, p53-deficient mice show neither hair loss nor apoptosis in the HF keratinocytes that maintained active proliferation after cyclophosphamide treatment. HF in p53 mutants are characterized by down-regulation of Fas and insulin-like growth factor-binding protein 3 and by increased expression of Bcl-2. These observations indicate that local pharmacological inhibition of p53 may be useful to prevent chemotherapy-associated hair loss.

Alopecia↗
PubMed2000

Different impact of p53 and p21 on the radiation response of mouse tissues.

Mammalian tissues differ dramatically in their sensitivity to genotoxic stress, although the mechanisms determining these differences remain largely unknown. To analyse the role of p53 and p21 in determination of tissue specificity to DNA damage in vivo, we compared the effects of gamma radiation on DNA synthesis on whole-body sections of wild type, p53-deficient and p21-deficient mice. A dramatic reduction in 14C-thymidine incorporation after gamma irradiation was observed in the majority of rapidly proliferating tissues of wild type and p21-/- but not in p53-/- mice, confirming the key role of p53 in determination of tissue response to genotoxic stress in vivo and suggesting that p53-mediated inhibition of DNA synthesis does not depend on p21. Rapid radiation induced p53-dependent apoptosis was mapped to the areas of high levels of p53 mRNA in radiation sensitive tissues analysed (white pulp in the spleen and bases of crypts in small intestine), indicating that p53 regulation at the mRNA level is a determinant of cellular sensitivity to genotoxic stress. High p53 mRNA expression is inherited as a recessive trait in cell-cell hybrids suggesting the involvement of a negative control mechanism in the regulation of p53 gene expression.

3T3 Cells↗
PubMed2000

p53 is involved in tumor necrosis factor-alpha-induced apoptosis in the human prostatic carcinoma cell line LNCaP.

The human prostatic carcinoma cell line LNCaP is sensitive to TNF-alpha treatment and expresses wild-type p53. To analyse the possible role of p53 in TNF-alpha-mediated apoptosis, we generated a derivative of LNCaP, LN-56, expressing a dominant-negative element of p53, GSE56. P53 inactivation in LN-56 was associated with an increased resistance to apoptosis induced by TNF-alpha. Surface expression of TNF-alpha receptors was unchanged in LN-56 compared to LNCaP. TNF-alpha treatment resulted in accumulation of p53 in LNCaP and upregulation of p21/WAF1. Activation of caspase-7 and PARP proteolysis were delayed in LN-56 under TNF-alpha treatment. TNF-alpha-induced apoptosis in LNCaP cells was accompanied by caspase-dependent proteolysis of p21/WAF1 and Rb, which was significantly attenuated in LN-56. Cytochrome c release was induced by TNF-alpha treatment in both cell lines, but caspase-9 was not activated. LNCaP and LN-56 were injected s.c. in nude mice and tumors were identified in all LN-56, but not LNCaP, bearing mice indicating that p53 plays an important role in growth control of prostatic neoplasms. Interestingly, accumulation of p53 in TNF-alpha-treated LNCaP cells was decreased in the presence of the caspase inhibitor Z-VAD-FMK, suggesting a new role of activated caspases in acceleration of p53 response. In summary, these results indicate that p53 is involved in TNF-alpha-mediated apoptosis in LNCaP.

Animals↗
PubMed2000

Expression of erbB receptors and their ligands in breast cancer: implications to biological behavior and therapeutic response.

Amplification and overexpression of the Her2/neu (c-erbB-2) growth factor receptor occurs in approximately 25% of early stage breast cancers. HER2/neu has been established as an important prognostic factor in early stage breast cancer in large patient populations and has been associated with shorter overall and disease free survival. New data are emerging to suggest that HER2/neu may be useful not only as a prognostic factor but also as a predictive marker for response to chemotherapeutics, anti-estrogens, and therapeutic regimens using anti-HER2/neu monoclonal antibodies. However, little is known of how other erbB receptors tyrosine kinases affect breast cancer biological behavior and response to therapy. In this review, we highlight recent data on Her2/neu as a prognostic and predictive marker of response to therapy, as well as how the other receptors of the erbB family affect the biological behavior of breast cancer.

Journal Article↗