Autophagy not only helps eliminate damaged, mutated, or genomically unstable cells, but also increases the chances of tumor cells overcoming the consequences of damage caused by chemotherapy. Autophagy induced by anthracyclines is cytoprotective in most tumor cell lines. Pharmacological or genetic blocking of autophagy in this case sensitizes tumor cells to therapy. Activation of cytoprotective autophagy can lead to chemoresistance, and with excessive enhancement, it can lead to energy depletion and trigger autophagic death. In some cases, cytotoxic autophagy develops under the action of anthracyclines, and its blocking increases cell survival. Activation of cytotoxic autophagy, on the contrary, triggers the process of “self-eating.” Modulation of autophagy in response to chemotherapeutic agents can be a double-edged sword for tumor cells, leading to both death and survival.

Contacts: Maria Anatolievna Zamkova zamkovam@gmail.com Introduction. Due to the toxicity of high doses of chemotherapy, low concentrations used in cancer treatment leads to the development of senescence phenotype in tumor cells, characterized by a block in the cell cycle progression and the absence of division; changes in the transcriptional and metabolic profile of cells. A negative consequence of this stage is acquisition of individual cells the ability to escape from senescence and return to re-proliferation.Aim. To estimate the effect of the duration of drug treatment of HCT116 tumor cells on their ability to escape from therapy induced senescence.Materials and methods. The senescence phenotype was confirmed by the analysis of β-galactosidase activity; cell cycle analysis; estimation of protein levels by western blotting. Colonies were stained with crystal violet dye.Results. In our study, we showed that the duration of HCT116 cells incubation with low-dose doxorubicin affects their ability to return to re-proliferation – increasing the treatment time using same drug dose reduces the process of colony formation. The duration of doxorubicin treatment does not affect the formation of the senescence phenotype, which was confirmed by analyzing different markers of this stage (changes in β-galactosidase activity, cell cycle analysis, assessment of p21 and γH2AX protein levels). However, there is a delay in the development of cellular response to DNA damage caused by doxorubicin in cells exposed to prolong treatment protocol (increase in β-galactosidase activity, formation of polyploid cells).Conclusion. The duration of doxorubicin treatment of HCT116 cancer cells affects long-term consequences, reducing the ability of senescent cells to escape this stage when the incubation time with the drug is extended.

Human epidermal growth factor receptor 2 (HER2) is overexpressed in numerous cancer cell types. Therapeutic antibodies and chimeric antigen receptors (CARs) against HER2 were developed to treat human tumors. The major limitation of anti-HER2 CAR-T lymphocyte therapy is attributable to the low HER2 expression in a wide range of normal tissues. Thus, side effects are caused by CAR lymphocyte "on-target off-tumor" reactions. We aimed to develop safer HER2-targeting CAR-based therapy. CAR constructs against HER2 tumor-associated antigen (TAA) for transient expression were delivered into target T and natural killer (NK) cells by an effective and safe non-viral transfection method via nucleofection, excluding the risk of mutations associated with viral transduction. Different in vitro end-point and real-time assays of the CAR lymphocyte antitumor cytotoxicity and in vivo human HER2-positive tumor xenograft mice model proved potent cytotoxic activity of the generated CAR-T-NK cells. Our data suggest transient expression of anti-HER2 CARs in plasmid vectors by human lymphocytes as a safer treatment for HER2-positive human cancers. We also conducted preliminary investigations to elucidate if fucosylated chondroitin sulfate may be used as a possible agent to decrease excessive cytokine production without negative impact on the CAR lymphocyte antitumor effect.

Plasticity of tumor cells (multitude of molecular regulation pathways) allows them to evade cytocidal effects of chemo- and/or radiation therapy. Metabolic adaptation of the surviving cells is based on transcriptional reprogramming. Similarly to the process of natural cell aging, specific features of the survived tumor cells comprise the therapy-induced senescence phenotype. Tumor cells with this phenotype differ from the parental cells since they become less responsive to drugs and form aggressive progeny. Importance of the problem is explained by the general biological significance of transcriptional reprogramming as a mechanism of adaptation to stress, and by the emerging potential of its pharmacological targeting. In this review we analyze the mechanisms of regulation of the therapy-induced tumor cell senescence, as well as new drug combinations aimed to prevent this clinically unfavorable phenomenon.

Introduction. Current approaches are being developed for adoptive cancer therapy using T-cells genetically modified with T-cell receptors (TCRs) with specificity for tumor antigens. The complexities of identifying antigen-specific TCRs in a patient’s repertoire and selecting therapeutic receptors necessitate the development of experimental strategies for generating tumor-specific T cells. One of such approaches could be the xenogeneic immunization of mice with human tumor cells. It seems plausible that the T cell repertoire stimulated by xenogeneic vaccination could be a source of TCRs suitable for adoptive cancer immunotherapy.Aim. To assess the prospects for using xenogeneic immunizations to generate tumor-specific memory T cells and identify their TCRs suitable for adoptive immunotherapy, we studied the dynamics of the secondary xenogeneic response in a model of induction of an immune response in mice to human melanoma cells.Materials and methods. Mice were immunized with human melanoma cells, and 45 days later, they were re-challenged with the immunizing tumor. The dynamics of the development of the secondary immune response in vivo and the composition of the involved effectors of adaptive immunity were analyzed by flow cytometry. The proliferation of lymphocytes from immune mice in response to human melanoma cells was evaluated in in vitro culture.Results. The secondary xenogeneic response was characterized by a more intense accumulation of T cells and the rapid development of the effector phase at the injection site of human melanoma. This correlated with an enhanced in vitro proliferative response of lymphocytes from immune animals to xenoantigens of the immunizing tumor. CD4+ and CD8+ memory T cells contributed equally to the development of a secondary response to human melanoma cells expressing HLA class I and II molecules. When only HLA class I was expressed on the cells of the immunizing xenogeneic tumor, CD8+ memory cells were formed, which dominated the secondary immune response.Conclusion. Our findings confirmed the formation of a specific immunological memory for xenoantigens during xenogeneic immunization. This suggests the possibility of generating xenogeneic TCRs specific for human tumor antigens, which opens up opportunities to developing approaches for screening among them for receptor variants suited for adoptive immunotherapy of human cancers.

Adoptive cell therapy (ACT) based on TCR- or CAR-T cells has become an efficient immunotherapeutic approach for the treatment of various diseases, including cancer. Previously, we developed a novel strategy for generating therapeutic T cell products based on chain-centric TCRs, in which either α- or β-chain dominates in cognate antigen recognition. To assess the suitability of our experimental approach for the clinical application and predict its possible adverse effects, in studies here, we evaluated the safety of the experimental TCRα-modified T cell product in mouse preclinical models. Our data showed no tumorigenic or mutagenic activity in vitro of TCRα-transduced T cells, indicating no genotoxicity of viral vectors used for the generation of the experimental T cell product. Adoptive transfer of TCRα-engineered T cells in a wide dose range didn`t disturb the host homeostasis and exhibited no acute toxicity or immunotoxicity in vivo. Based on pharmacokinetics and pharmacodynamics analysis here, modified T cells rapidly penetrated and distributed in many viscera after infusion. Histological evaluations revealed no pathological changes in organs caused by T cells accumulation, indicating the absence of non-specific off-target activity or cross-reactivity of the therapeutic TCRα. Studies here provide valuable information on the potential safety of TCRα-T cell based ACT that could be extrapolated to possible effects in a human host.

Both TCRα and TCRβ types of T-cell receptors contribute to antigen recognition. However, some TCRs have chain centricity, which means that either the α-chain or the β-chain dictates the peptide-MHC complex specificity. Most earlier reports investigated the role of well-studied β-chains in antigen recognition by TCRαβ. In a previous study, we identified TCRs specific to the H-2Kb molecule. In the present work, we generated transgenic mice carrying the α-chain of this TCR. We found that these transgenic mice rejected EL-4 tumor cells bearing alloantigen H-2Kb more effectively than wild-type mice and similarly to mice with established specific memory T cells. Moreover, we found that T cells transduced with this TCRα can inhibit EL-4 cell growth in vitro and in vivo. We also found that transgenic mice recruit fewer CD8 T cells into the peritoneal cavity at the peak of the immune response and had a significantly higher number of central memory CD8 T cells in the spleen of intact transgenic mice compared to intact wild-type control. These results indicate the ability of a single transgenic α-chain of the H-2Kb-specific TCR to determine specific recognition of the H-2Kb molecule by a repertoire of T lymphocytes and to rapidly reject H-2Kb-bearing lymphoma cells.

Background. Wide use of glucocorticoids therapy for neoplasms, autoimmune diseases and allergies is associated with suppression of adaptive immunity that requires profound study of their immunoregulatory properties and immunotoxicity.Results. In this work, using our model of selective activation of mouse CD8+ memory cells in the mixed lymphocyte reaction (MLR) in vitro, we show for the first time that intraperitoneal injection of high dose hydrocortisone (2.5 mg per animal) allows to detect memory cells in the thymus of animals immunized with allogeneic tumor cells. Similar to memory cells from other lymphoid organs, hydrocortisone-resistant thymic lymphocytes from immune animals respond on allogeneic stimulators subjected to severe heat shock and are immunologically specific to immunizing alloantigen. Thus, cortisone-resistant thymocytes are partially or completely represented by memory cells. We also show here that memory responses of heterozygotes on TCR a-chain knock-out (genetically incapable to secondary rearrangement of TCR achains) are significantly enhanced as compared with the ones of wild type mice.Conclusion. These findings allows to suggest the hypothesis according to which memory T cell clones proliferating in primary immune response migrate into thymus providing necessary microenvironment for reexpression of recombinases. After editing of genes encoding TCR achains, such T lymphocytes can return to peripheral repertoire maintaining its wideness.

In wide number of approaches to treatment of cancer immunotherapy plays special role. This approach exploits capabilities of immune system to support genetic constancy of different cells and tissues of the organism. Immunotherapy is designed to induce tumor cell destruction by T-lymphocytes whose receptors can recognize peptides of mutant proteins complexed with the molecules of the major histocompatibility complex. In clinical practice T-lymphocytes can result in sustained and complete responses in patients whose cancers were resistant to available treatment options. Recent evidences suggest that efficiency of such therapy generally depends on metabolic properties of T-lymphocytes. A number of approaches allows modulate T-cell metabolism providing strategies to optimize activity of anti-tumor T-lymphocytes.

Findings in experimental oncology in beginning of last century and subsequent achievements of genetics of tissue compatibility resulted in divergence of transplantational immunology and oncoimmunology. However, central achievements of both scientific fields are based on unified phenomenon of interaction between T-cell receptor (TCR) and histocompatibility molecules. In this review we describe the history of ideas, achievements and unique experience of the team of the Laboratory of Regulatory Mechanisms in Immunity at Scientific Research Institute of Carcinogenesis, N.N. Blokhin Russian Cancer Research Center for all time of existence. This experience shows that efficiency of immunological defense including immunological surveillance are critically influenced by T-cell receptor repertoire. Transgenesis of individual chains of TCR is one of possible means to manage T-cell repertoire. Functional outcomes of transgenesis may be different due to diverse extent of dependence of α- and β-chains expression on the rules of allelic exclusion. Expression of transgenic β-chains results in the expansion of TCR repertoire diversity. Expression of β-chains is under strong control by allelic exclusion, resulting in formation of repertoire bearing mainly invariant transgenic β-chain pared with different α-chains and overall narrowing of repertoire. Earlier, we cloned genes encoding α- and β-chains of TCR of CD8+ memory cells specific to histocompatibility molecule H-2Kb . After introduction them in zigotes we have obtained transgenic mouse strains, which could be used for modeling of interactions between tumor cells and immune system of recipient. Normally, B10. D2 (R101) mice reject lymphoma EL4 cells in 12–14 days after transplantation, in spite of the fact, that allogeneic difference between B10. D2 (R101) (Kd Id Db ) mice and lymphoma EL4 (H-2b) cells is only in one product of MHC, the H-2Kb molecule. Transgenics carrying β-chains of TCR displayed compromised immunity to tumor cells resulting to their long persistence, tumor progression, the loss of H-2Kb molecule and death in 2–3 months after transplantation. This model allows to see all three phases of interaction between tumor and immune system of recipient – elimination, equilibrium and escape. Against, transgenics carrying α-chain reject tumor cells much more quickly, as in secondary immune response, in 3–6 days after transplantation. This rejection was mediated by intraepithelial T lymphocytes displaying features of resident memory cells – inability to recirculation, expression of CD103 and early activation antigen CD69 and intermediate density of T-cell markers CD3 and CD8. The capability to be located in nonlymphoid tissue and quickly destroy tumor cells makes them to be the most probable candidate to perform immunological surveillance functions.

Insulin receptors are widely distributed in the brain, where they play roles in synaptic function, memory formation, and neuroprotection. Autophosphorylation of the receptor in response to insulin stimulation is a critical step in receptor activation. In neurons, insulin stimulation leads to a rise in mitochondrial H2O2 production, which plays a role in receptor autophosphorylation. However, the kinetic characteristics of the H2O2 signal and its functional relationships with the insulin receptor during the autophosphorylation process in neurons remain unexplored to date.

We have performed simultaneous real time recording of the intracellular level of Ca2+ ([Ca2+]i) and intracellular localization of protein kinase C (PKC) in cultured rat cortical neurons. The neurons were transfected with a plasmid that encoded a chimerical protein of PKCβII and green fluorescent protein (GFP) and loaded with fura-2FF. In the resting neurons, PKCβII-GFP was uniformly distributed in the cytoplasm of cortical neurons. The primary [Ca2+]i increase caused by glutamate was accompanied by translocation of PKCβII-GFP from the cytosol to the plasma membrane. A secondary [Ca2+]i elevation (destabilization of calcium homeostasis) was associated with retranslocation of PKCβII-GFP from the plasma membrane to the cytoplasmic organelle-like structures. Similar organelle-like structures were observed after immunohistochemical staining of PKCβII in cultured cerebellar granule cells and cortical neurons subjected to long-term glutamate treatment. It seems that PKCβII was active in these structures because the receptor for activated C kinase RACK1 also translocated into similar structures. Formation of clusters by PKCβII was calcium-dependent because the clusters also formed after treatment of neurons with calcium ionophore ionomycin. No retranslocation of PKC was observed after treatment with the calcium-independent activator of PKCβII phorbol-myristate acetate (PMA); in this case both PKCβII and RACK1 remained on the plasma membrane of neurons. The results obtained suggest that deregulation of neuronal calcium homeostasis during hyperstimulation of glutamate receptors induces specific changes in the localization of active PKCβII.

Two large bodies of evidence suggest that dysfunctional cerebral insulin receptor signaling and mitochondrial dysfunction both contribute to pathogenesis of Alzheimer's disease (AD). However, exact molecular link between these abnormalities remains unclear. The aim of the study is to provide evidence that (1) conditions affecting mitochondrial respiration may induce dysfunctional insulin receptor activation in neurons, and (2) targeting the mitochondrial respiration has therapeutic effects against AD type cognitive deficits in animal models. Insulin receptor activation in a primary culture of rat cerebellar granule neurons was assessed by measuring the insulin receptor tyrosine phosphorylation. AD type cognitive deficits in rats were induced by injection of beta-amyloid peptide (25–35) into nucleus basalis magnocellularis or by chronic cerebral hypoperfusion induced by permanent bilateral occlusion of the common carotid arteries (2VO). Treatment efficacy was assessed in terms of cognitive performance and whole-brain N-acetylaspartate (NAA) levels measured by 1H-MRS in vivo. Optimal insulin receptor activation in neurons is required in a spike of H2O2 derived from mitochondrial respiration during the insulin stimulation. Mitochondrial inhibitors, malonate and FCCP, and H2O2 scavenger, N-acetylcysteine, almost completely abolished both insulin-induced H2O2 release and insulin receptor tyrosine phosphorylation. These results suggest that a condition affecting mitochondrial respiration may induce dysfunctional insulin receptor activation in neurons. On the contrary, stimulation of respiration with succinate, in form of its disodium or dicholine salts (CS), significantly enhanced insulin receptor activation in response to suboptimal insulin concentrations. In vivo, CS significantly normalized NAA levels in brain and ameliorated cognitive deficits in 2VO and bAmyloid-induced rats, when administered for 7 days. All the in vivo effects were long-lasting, extending at least two weeks beyond the 7-day treatment period. As compared to highly effective CS treatment, a reference choline compound, choline chloride, demonstrated no significant effects. Conditions affecting mitochondrial respiration may induce dysfunctional insulin receptor activation in neurons. Targeting mitochondrial respiration is a promising strategy for the treatment of AD type cognitive deficits and should encourage further in-depth investigations.

The primary culture of rat cerebellar neurons was used to study protein kinase C activity, intracellular variations in calcium concentration ([Ca2+]i), changes in the mitochondrial potential, and neuronal death during hyperstimulation of glutamate receptors and after 24-h incubation with phorbol ester. Prolonged exposure of neurons to glutamate (100 µM, 45 min) was followed by the development of delayed calcium dysregulation. Protein kinase C activity depended on the time of cell incubation with glutamate. Protein kinase C activity increased in response to application of glutamate for 15 min. However, protein kinase C activity decreased after 45-min exposure to glutamate and development of delayed calcium dysregulation. Protein kinase C activity was nearly undetected after 24-h preincubation of neurons with phorbol ester. Under these conditions, delayed calcium dysregulation developed more slowly and was observed in a smaller number of neurons. Neuronal death decreased to 2±1%. Our results suggest that protein kinase C plays an important role in death of neurons, which exhibit delayed calcium dysregulation during glutamate treatment.

Background Accumulated evidence suggests that insulin resistance and impairments in cerebral insulin receptor signaling may contribute to age-related cognitive deficits and Alzheimer's disease. The enhancement of insulin receptor signaling is, therefore, a promising strategy for the treatment of age-related cognitive disorders. The mitochondrial respiratory chain, being involved in insulin-stimulated H 2 O 2 production, has been identified recently as a potential target for the enhancement of insulin signaling. The aim of the present study is to examine: (1) whether a specific respiratory substrate, dicholine salt of succinic acid (CS), can enhance insulin-stimulated insulin receptor autophosphorylation in neurons, and (2) whether CS can ameliorate cognitive deficits of various origins in animal models. Results In a primary culture of cerebellar granule neurons, CS significantly enhanced insulin-stimulated insulin receptor autophosphorylation. In animal models, CS significantly ameliorated cognitive deficits, when administered intraperitoneally for 7 days. In 16-month-old middle-aged C57Bl/6 mice (a model of normal aging), CS enhanced spatial learning in the Morris water maze, spontaneous locomotor activity, passive avoidance performance, and increased brain N-acetylaspartate/creatine levels, as compared to the age-matched control (saline). In rats with chronic cerebral hypoperfusion, CS enhanced spatial learning, passive avoidance performance, and increased brain N-acetylaspartate/creatine levels, as compared to control rats (saline). In rats with beta-amyloid peptide-(25–35)-induced amnesia, CS enhanced passive avoidance performance and increased activity of brain choline acetyltransferase, as compared to control rats (saline). In all used models, CS effects lasted beyond the seven-day treatment period and were found to be significant about two weeks following the treatment. Conclusion The results of the present study suggest that dicholine salt of succinic acid, a novel neuronal insulin sensitizer, ameliorates cognitive deficits and neuronal dysfunctions in animal models relevant to age-related cognitive impairments, vascular dementia, and Alzheimer's disease.

Background: Accumulated evidence suggests that hydrogen peroxide (H2O2) generated in cells during insulin stimulation plays an integral role in insulin receptor signal transduction. The role of insulin- induced H2O2 in neuronal insulin receptor activation and the origin of insulin- induced H2O2 in neurons remain unclear. The aim of the present study is to test the following hypotheses (1) whether insulin- induced H2O2 is required for insulin receptor autophosphorylation in neurons, and (2) whether mitochondrial respiratory chain is involved in insulin- stimulated H2O2 production, thus playing an integral role in insulin receptor autophosphorylation in neurons.Results: Insulin stimulation elicited rapid insulin receptor autophosphorylation accompanied by an increase in H2O2 release from cultured cerebellar granule neurons (CGN). N-acetylcysteine (NAC), a H2O2 scavenger, inhibited both insulin-stimulated H2O2 release and insulin-stimulated autophosphorylation of insulin receptor. Inhibitors of respiratory chain-mediated H2O2 production, malonate and carbonyl cyanide-4-(trifluoromethoxy)-phenylhydrazone (FCCP), inhibited both insulin-stimulated H2O2 release from neurons and insulin-stimulated autophosphorylation of insulin receptor. Dicholine salt of succinic acid, a respiratory substrate, significantly enhanced the effect of suboptimal insulin concentration on the insulin receptor autophosphorylation in CGN.Conclusion: Results of the present study suggest that insulin-induced H2O2 is required for the enhancement of insulin receptor autophosphorylation in neurons. The mitochondrial respiratory chain is involved in insulin-stimulated H2O2 production, thus playing an integral role in the insulin receptor autophosphorylation in neurons.