Partial restoration of the actin cytoskeleton in transformed Syrian hamster fibroblasts selected for low levels of ‘typical’ multidrug resistance

AbstractTwo independent colchicine (CLC)-resistant sublines of Rous sarcoma virus-transformed Syrian hamster flbroblasts were isolated. Each subline represented variants with 11- and 12.4-fold resistance, respectively, their 23- and 23.7-fold resistant descendants, as well as variants cultured in CLC-free medium for 10 months without loss of resistance. All variants demonstrated ‘typical’ multidrug resistance. The parental cells contained actin in dispersed form, as determined by rhodamine-phalloidin staining. In contrast, already in 11- and 12.4-fold resistant sublines up to 30% of cells demonstrated restored stress fibers. Cultivation in CLC-free medium leads to the accumulation of cells with a partially restored actin cytoskeleton. Putative mechanisms of up-regulation of stress fiber assembly in cells with P-glycoprotein-mediated multidrug resistance are discussed

Influence of RARα gene on MDR1 expression and P-glycoprotein function in human leukemic cells

BACKGROUND: Multidrug resistance (MDR) phenotype of malignant cells is the major problem in the chemotherapy of neoplasia. The treatment of leukemia with retinoids is aimed on the induction of leukemic cells differentiation. However the interconnections between retinoid regulated differentiation of leukemic cells and regulation of MDR remains unclear. METHODS: Four lines of cultured leukemic cells of diverse types of differentiation were infected with RARα gene and stable transfectants were isolated. We investigated the differentiation of these cells as well as the expression of RARα and MDR1 genes and P-glycoprotein (Pgp, MDR protein) functional activity in these cells. RESULTS: All RARα transfected sublines demonstrated the increase in the quantity of RARα mRNA. All these sublines became more differentiated. Intrinsic activity of MDR1 gene (but not Pgp functional activity) was increased in one of the transfectants. All-trans-retinoic acid (ATRA) induced Pgp activity in two of three infectants to a larger extent than in parental cells. CONCLUSION: The data show that RARα regulates MDR1/ Pgp activity in human leukemic cells, in the first place, Pgp activity induced by ATRA. These results show that RARα overexpression in leukemic cells could result in MDR

Новое в изучении множественной лекарственной устойчивости клеток рака молочной железы

Breast cancer (BC) is the most common cancer among women in Russia. One of the main treatment methods of BC is systemic chemotherapy. Multidrug resistance of tumor cells (MDR) is the important hindrance on the way to successful chemotherapy. The new data concerning molecular mechanisms of MDR will be presented in this review. The recent data concerning some new biological prognostic markers will be also discussed. There are data showing that transporters of ABC family (ABC transporters) influence tumor progression not only by MDR induction but also by the influence on the traits of malignancy in tumor cells. The results of the studies of ABC transporters, participation in the processes of accumulation of tumor stem cells under the influence of chemotherapy will be discussed. The problem of the participation of ABC transporters in the phenomenon of influence of PI3K/AKT/PTEN signal transduction pathway on the MDR regulation is discussed. The results of the studies of the role of microRNA deregulation in breast cancer drug resistance as well as studies of some epigenetic mechanisms of MDR regulation will be considered. Protein phosphatase 2A (PP2A, serine/threonine phosphatase), PTK7 (protein tyrosine kinase 7). fascin (an actin bundling cytoskeletal protein) multifunctional YB-1 protein will considered as new BC prognostic markers. The perspectives of MDR studies will be discussed as well.Рак молочной железы (РМЖ) – самое распространенное онкологическое заболевание у женщин в России. Одним из основных видов лечения РМЖ является системная химиотерапия. Серьезным препятствием на пути успешного лечения РМЖ остается устойчивость опухолей к лекарственным препаратам, в первую очередь – множественная лекарственная устойчивость (МЛУ). В данном обзоре представлены данные последнего времени о молекулярных механизмах МЛУ, а также о некоторых новых биологических прогностических маркерах РМЖ. Разбираются данные, показывающие, что транспортные белки семейства АВС (АВС-транспортеры) влияют на опухолевую прогрессию не только путем индукции лекарственной устойчивости клеток, но и в связи с их участием в экспрессии признаков малигнизации. Рассмотрены результаты, свидетельствующие об участии АВС-транспортеров в процессах накопления стволовых клеток опухолей под влиянием химиотерапии. Обсуждается проблема участия сигнального пути PI3K/AKT/PTEN в регуляции МЛУ путем его влияния на активность АВС-транспортеров. Рассмотрены данные о влиянии нарушений регуляции микроРНК на МЛУ РМЖ, а также некоторые эпигенетические механизмы регуляции МЛУ. Среди новых прогностических маркеров МЛУ РМЖ обсуждаются серин-треониновая фосфатаза 2А, рецепторная протеинкиназа PTK7, фасцин – белок, способствующий связыванию нитей актина в пучки, многофункциональный белок YB-1. Обсуждаются перспективы исследований МЛУ при РМЖ

Некоторые новые аспекты исследований множественной лекарственной устойчивости опухолевых клеток

Multidrug resistance (MDR) of tumor cells is the resistance to a broad spectrum of structurally unrelated cytotoxic drugs with different mechanisms of action. One of the main causes of MDR phenotype is the activity of ATP-binding cassette transporters (ABC transporters). ABC transporters efflux toxic compounds from the cells. All living cells contain ABC transporters. This review is dedicated to the studies of three-dimensional structure of ABC transporters, to the data concerning MDR evolution in tumor cell populations. Some information about molecular mechanisms of MDR evolution is also presented.Множественная лекарственная устойчивость (МЛУ) опухолевых клеток – резистентность клетки одновременно к большому количеству веществ, разных по химическому строению и механизму действия. Одним из важнейших и наиболее исследованных механизмов МЛУ является активность транспортных белков семейства АВС (АВС-транспортеры). АВС-транспортеры, выводящие токсические соединения из клеток, и гены, кодирующие АВС-транспортеры, содержатся во всех живых клетках. В обзоре рассматриваются работы, посвященные исследованию трехмерной структуры АВС-транспортеров; результаты, полученные при изучении эволюции МЛУ, определяемой АВС-транспортерами, а также некоторые молекулярные механизмы, которые могут определять эволюцию МЛУ

Nephrological aspects of surgical weight correction in morbid obesity

Obesity, including morbid obesity, is a growing worldwide problem. The adverse effect of obesity on the kidneys is associated with the development of comorbid conditions, such as insulin resistance (IR), metabolic syndrome (MS), diabetes mellitus (DM), arterial hypertension (AH), which are the recognized risk factors of chronic kidney disease (СKD). Obesity also causes direct kidney damage with the development of non-immune focal segmental glomerulosclerosis. The leading pathophysiological mechanisms of kidney damage in obesity are intrarenal hemodynamic disorders with the formation of hyperfiltration and damaging effects of adipokines produced by adipose tissue. Bariatric surgery (BS) has taken a leading position in the treatment of morbid obesity, demonstrating its effectiveness not only in long-term weight loss, but also in the correction of IR, MS, DM, AH. Nephroprotective effect of significant and persistent weight loss is caused by the elimination of hyperfiltration and damaging effect of adipokines. Results of the observational studies of the immediate and long-term effects of BS have demonstrated positive renal outcomes, in particular, the decrease in albuminuria/proteinuria, the improvement or stabilization of glomerular filtration rate, the delay of end-stage renal failure development; surgical correction of body weight in dialysis patients with morbid obesity lets them realize subsequent kidney transplantation. Large, randomized prospective studies with a longer follow-up are needed; analysis of the long-term renal consequences of BS in obesity patients with pre-existing renal impairment, including dialysis patients, is required; stratification of the BS risk of renal complications (acute kidney damage, nephrolithiasis, nephrocalcinosis) and effective strategy for managing these risks need to be developed

Cognitive function and metabolic features in male Sprague-Dawley rats receiving high-fat and low-calorie diets

Background: Obesity is a risk factor for cognitive disorders. However, it is still unknown whether low-calorie diet will improve cognitive function in obese patients. Aim: To evaluate cognitive function and metabolic features in male Sprague-Dawley rats receiving high-fat and low-calorie diets. Materials and methods: The work was carried out on Sprague Dawley male rats (n = 32), which were divided into 2 groups with 16 animals in each group: Control (normal / low-calorie diet) and Obesity (high-fat diet). In 90 days the rats of the Control group were transferred to a low-calorie diet, the rats of the Obesity group continued to receive high-fat diet. To assess motor activity and cognitive functions at the end of the study (180 days), following behavioral tests were conducted: "open field", "tapering beam", "elevated plus-maze" (EPM) and "passive avoidance reaction". During the study glucose tolerance test were performed: at baseline (GTT 1) and in 30 days (GTT 2). Results: Obesity group rats gained weight significantly faster than the control animals (547.69 ± 11.32 g against 442.8 ± 19.8 g at study end, p = 0.0001). GTT 2 showed normal carbohydrate metabolism in control group, postprandial hyperglycemia in obesity group. Testing in the open field showed that the rats of the obesity group moved more actively across the installation area than the control ones: the total distance covered was 9.352 ± 0.932 m against 6.781 ± 0.951 m, p = 0.046. The results of a tapering beam test showed that the number of hind limb extrusions in obese rats significantly exceeded this parameter in control group (33.7 ± 3 vs. 15.7 ± 2.7, p = 0.0001), test time in both groups did not differ. When testing in EPM, there was no significant difference in any of the key test parameters between the groups. However, the number of looking out from the closed arms in animals of the obesity group was significantly higher than in the control group (4.19 ± 0.6 vs. 2.30 ± 0.58, p = 0.044). When testing the reproduction of conditional reactions of passive avoidance it was shown that after day 1 of the pain stimulation application the latent period of transition to the dark compartment in the obesity group was significantly higher than that of the control group (180.0 ± 0.0 vs. 128 86 ± 21.45, p = 0.008). This indicates a better preservation of the memorial trail compared to the "control" rats. By the end of the study 30% of animals in the control group died. Conclusions: Rats on high-fat diet were more active, less anxious and showed better results in training tests comparing to animals on low-calorie diet. Adherence to low-calorie diet may be harmful for cognitive functions

RegPredict: an integrated system for regulon inference in prokaryotes by comparative genomics approach

RegPredict web server is designed to provide comparative genomics tools for reconstruction and analysis of microbial regulons using comparative genomics approach. The server allows the user to rapidly generate reference sets of regulons and regulatory motif profiles in a group of prokaryotic genomes. The new concept of a cluster of co-regulated orthologous operons allows the user to distribute the analysis of large regulons and to perform the comparative analysis of multiple clusters independently. Two major workflows currently implemented in RegPredict are: (i) regulon reconstruction for a known regulatory motif and (ii) ab initio inference of a novel regulon using several scenarios for the generation of starting gene sets. RegPredict provides a comprehensive collection of manually curated positional weight matrices of regulatory motifs. It is based on genomic sequences, ortholog and operon predictions from the MicrobesOnline. An interactive web interface of RegPredict integrates and presents diverse genomic and functional information about the candidate regulon members from several web resources. RegPredict is freely accessible at http://regpredict.lbl.gov

Arc/Arg3.1 expression in the brain tissues during the learning process in Alzheimer's disease animal models

Introduction. Arc/Arg3.1 is a common marker of neuronal activation for learning and memorizing. Some experimental data show the Arc/Arg3.1 expression in the post-mitotic neurons of the neurogenic niches. At the same time, we still have to understand the importance of such an expression for neurogenesis induced by the learning or memorizing processes, in health and in disease. Objective: to evaluate the changes in Arc/Arg3.1 expression in the post-mitotic neurons and to assess the proliferative activity of the neurogenic niche cells in Alzheimer's disease animal models. Materials and methods. We divided the C57Bl/6В mice into 2 groups: experimental (n = 15) and control (n = 15). The experimental group were injected with the amyloid- oligomers 2535 in their CA1 hippocampal region while the control mice received normal saline injections in the same region. Passive Avoidance Test (PAT) was used to assess the cognitive functions from the day 9 after the intervention. One hour after each test session we collected the samples of brain tissues to immunohistochemically assess them for the Arc/Arg3.1 expression and PCNA cell proliferation marker. Results. At day 11 the count of Arc/Arg3.1+NeuN+ cells in the subgranular zone had significantly increased. In animal neurodegeneration models the 1st and 2nd PAT sessions were associated with a significant increase in Arc/Arg3.1+NeuN+ cells, although by the day 11 their count significantly decreased. The count of Arc/Arg3.1+ cells in the subventricular and subgranular zones had increased after the 3rd PAT session in the control group while in Alzheimer's disease animal models this was observed only after the 2nd PAT session. Preserved Arc/Arg3.1 expression in the subventricular zone is associated with the increased PCNA cell prolifera- tion marker expression. At the same time, the toxic effect of the amyloid- oligomers suppressed the cells' proliferative activity in the subgranular zone at day 9. Conclusions. Despite the toxic effect of the amyloid- oligomers 2535, the post-mitotic neurons of the neurogenic niches retained the ability to express Arc/Arg3.1 in vivo. The obtained results show a transient increase in sensitivity of the post-mitotic neurons of the neurogenic niches for the learning stimuli in the early stages of the Alzheimer-type neurodegeneration