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Gene inactivation of the cyclin‑dependent kinase inhibitors p16

Hofbauer cells are macrophages residing in the stroma of placental villi and play a number of roles during normal pregnancy, as well as pathological conditions. A morphometric analysis of Hofbauer cells, in particular to investigate the number of cells, their size and shape in samples of normal human placenta from 1st trimester, term and with chorioamnionitis was performed. Tissue samples were immunostained for CD206 antigen and evaluated using ImageJ software. We detected significant changes in number and morphology of HBCs between normal placenta and placenta with chorioamnionitis samples. In chorioamnionitis, the cells were unevenly distributed within the villi, generally present in higher numbers, larger and more elongated than those in normal 1st trimester and term placenta.

INTRODUCTION There are only sporadic references in literature regarding general medicine and dentistry student´s preparedness for Histology, study resources and how students might use them in the era of virtual microscopy. METHODS A structured questionnaire was used to evaluate students´ opinion, with 192 students of general medicine and 82 students of dentistry responding. RESULTS The dentistry students evaluate their previous knowledge of basic high school disciplines as less helpful when compared to their general medicine colleagues, but this difference diminishes during the first year of medical school studies. Students of dentistry display a better orientation in the amount of study resources (electronic vs printed) and also the ways of their use (practical vs theoretical preparation). The main problems surfacing in the study of Histology have been: the lack of time due to the high demands of Anatomy, problems with correct identification of structures in specimens and correct orientation in a large number of available study resources. Students indicate that they would appreciate the introduction of interactive exercise tests to verify practical and theoretical knowledge. CONCLUSION We revealed significant differences between students of general medicine and dentistry in terms of student´s preparedness and learning habits. According to our findings, it is still necessary to further develop teaching methods utilising virtual microscopy, taking into account the needs of both general medicine and dental school students.

There is growing evidence that soluble epoxide hydrolase (sEH) may play a role in cell differentiation. sEH metabolizes biologically highly active and generally cytoprotective epoxyeicosatrienoic acids (EETs), generated from arachidonic acid metabolism by CYP epoxygenases (CYP2C and CYP2J subfamilies), to less active corresponding diols. We investigated the effect of sEH inhibitor (TPPU) on the expression of villin, CYP2C8, CYP2C9, CYP2J2, and sEH in undifferentiated and in vitro differentiated HT-29 and Caco2 cell lines. The administration of 10 μM TPPU on differentiated HT-29 and Caco2 cells resulted in a significant decrease in expression of villin, a marker for intestinal cell differentiation. It was accompanied by a disruption of the brush border when microvilli appeared sparse and short in atomic force microscope scans of HT-29 cells. Although inhibition of sEH in differentiated HT-29 and Caco2 cells led to an increase in sEH expression in both cell lines, this treatment had an opposite effect on CYP2J2 expression in HT-29 and Caco2 cells. In addition, tissue samples of colorectal carcinoma and adjacent normal tissues from 45 patients were immunostained for sEH and villin. We detected a significant decrease in the expression of both proteins in colorectal carcinoma in comparison to adjacent normal tissue, and the decrease in both sEH and villin expression revealed a moderate positive association. Taken together, our results showed that sEH is an important player in intestinal cell differentiation.

We investigated the effects of PPARα activators fenofibrate and WY-14643 as well as the PPARα inhibitor GW6471 on the PI3K/Akt/PTEN pathway of intestinal cell differentiation. Our previous study showed that all these compounds increased the expression of villin, a specific marker of intestinal cell differentiation in HT-29 and Caco2 cells. Our current results confirmed the central role of lipid messenger phosphatidylinositol-4,5-bisphosphate (PIP2), a known player in brush border formation, in mediating the effects of tested PPARα ligands. Although all tested compounds increased its levels, surprisingly, each of them affected different PIP2-metabolizing enzymes, especially the levels of PIP5K1C and PTEN. Moreover, we found a positive relationship between the expression of PPARα itself and PIP2 as well as PIP5K1C. By contrast, PPARα was negatively correlated with PTEN. However, the expression of antigens of interest was independent of PPARα subcellular localization, suggesting that it is not directly involved in their regulation. In colorectal carcinoma tissues we found a decrease in PTEN expression, which was accompanied by a change in its subcellular localization. This change was also observed for the regulatory subunit of PI3K. Taken together, our data revealed that fenofibrate, WY-14643, and GW6471 affected different members of the PI3K/Akt/PTEN pathway. However, these effects were PPARα-independent.

Aims Hofbauer cells (HBCs) are placental macrophages playing various roles during normal and complicated pregnancies, and of the latter, chorioamnionitis is the most frequent. Methods In placenta with chorioamnionitis, we examined immunohistochemical expression profiles of IL-1β, IL-10, and their potential regulators, CYP2C8 and soluble epoxide hydrolase (sEH), in Hofbauer cells and compared the results with our previously published data for normal placenta. Results We found that the expression profiles of the studied proteins in Hofbauer cells in chorioamnionitis differs from normal placenta. In chorioamnionitis, HBCs showed a moderate expression of IL-1β together with a weak expression of IL-10 and CYP2C8. Contrary to normal placenta, HBCs in chorioamnionitis express sEH. We demonstrated a moderate positive correlation between the expression of CYP2C8 and sEH in chorioamnionitis (Spearman r = 0.5654), suggesting enhanced degradation of anti-inflammatory epoxyeicosatrienoic acids. Moreover, the relations of IL-1β and IL-10 to CYP2C8, previously described in normal placenta, disappeared. Furthermore, a weak expression of anti-inflammatory IL-10 in chorioamnionitis was accompanied by change in circularity of HBCs (Spearman r = 0.8193). Conclusion Taken together, these findings suggest a possible alteration of the anti-inflammatory role of HBCs and its regulation in chorioamnionitis.

Software based analyses of immunohistochemical staining are designed for obtaining quantitative, reproducible, and objective data. However, often times only a certain type of positive cells or structures need to be quantified thus whole image analysis cannot be performed. Such an example is Hofbauer placental cells, which show positivity of some antigens together with trophoblast, but only Hofbauer cells represent the regions of interest (ROIs). Two independent observers evaluated the immunohistochemical staining intensity of Hofbauer cells in placenta samples stained for cytoplasmic antigens by ImageJ, QuPath and light microscopy. Thus, the precise manual determination of ROIs, i.e. Hofbauer cells, was necessary. We detected low inter-observer variability in staining intensity. Almost perfect agreement between observers was reached for ImageJ and QuPath whilst substantial agreement was reached for light microscopy evaluation. As for the comparison of ImageJ, QuPath and light microscopy, the agreement of all three methods (identical immunohistochemical intensity) was achieved for 38.1% samples. The almost perfect agreement of staining intensities was reached between ImageJ and QuPath, and moderate agreement for comparison of the light microscopy to both software. Software analyses are much more time-consuming, thus their utilization is at least questionable to evaluate ROIs with selection.

INTRODUCTION Virtual microscopy, used as a method to teach histology, has many undeniable advantages. However, the usefulness of this method is somewhat limited by the difficulties students face in finding their way through huge amounts of digital data, compounded by decreased interaction between students and teachers. We describe the results of a recent pilot project which combined the modern teaching methods of active learning, where students themselves present histological slides and make use of the virtual microscopy system. METHODS Students' responses to a structured questionnaire and examination results were evaluated. RESULTS We found that a combination of both electronic materials and textbooks was commonly used by students to prepare for practical teaching sessions, with electronic resources being used regularly by the majority of students. No statistically relevant differences were found between the approaches of dentistry vs general medicine students. Cooperation between students' groups during the preparation for individual presentations was seen to be beneficial by a majority of dentistry students; they reported that the introduction of student-led presentations improved their quality of preparation for practical lessons, as well as increasing their participation and activity level in the lessons themselves. These different approaches and motivations between students of dentistry and general medicine are reflected in the test results where dentistry students are more successful. CONCLUSION We confirm that there are differences in motivation, approaches and examination results between both groups of students, which should be taken into account and which could lead to differentiation of future curricula for both study courses.

Introduction: Cytochrome (CYP) epoxygenases (CYP2C and CYP2J) and soluble epoxide hydrolase (sEH) participate in the metabolism of arachidonic acid and may also have a potential role in enterocyte differentiation. The first critical step in the study of intestinal cell differentiation is the determination of a suitable in vitro model, which must be as similar as possible to the conditions of a living organism. It is known that HT-29 and Caco2 cell lines derived from human colorectal carcinomas can differentiate into enterocyte-like cells in appropriate culture conditions. Material and Methods: We tested 4 different approaches of enterocyte-like differentiation and determined the most appropriate culture conditions for each model. Subsequently, the changes in the expression of CYP epoxygenases and sEH in undifferentiated and differentiated cells were measured by In-Cell ELISA. These results were compared with immunohistochemical profiles of expression of CYP epoxygenases and sEH in samples of human embryonic and fetal intestines as well as adult duodenum and colon. Results: Our results show that sodium butyrate (NaBt)-differentiated HT-29 cells and spontaneously differentiated Caco2 cells resemble CYP epoxygenases and sEH profiles, corresponding with different types of intestines. Conclusion: Our study revealed that the most suitable models for the study of the role of CYP epoxygenases and sEH expression in differentiation of intestinal epithelium are NaBt-differentiated HT-29 cells and spontaneously differentiated Caco2 cells.

CYP2C and CYP2 J enzymes, commonly named as cytochrome P450 (CYP) epoxygenases, convert arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EETs), biologically active eicosanoids with many functions in organism. EETs are rapidly hydrolysed to less active dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). We investigated spatio-temporal expression pattern of CYP2C8, CYP2C9, CYP2 J2 and sEH in normal human placenta by immunohistochemical method. In the villous trophoblast, CYP2C8 was the most abundant protein. Its expression is higher than the CYP2C9 and CYP2 J2 in the cytotrophoblast in the embryonic stage of development and remains higher in syncytiotrophoblast of term placenta. Unlike to CYP2C8, CYP2C9 and CYP2 J2 expression decrease in term placenta. sEH expression increases with gestation age and is strictly limited to cytotrophoblast in embryonic and foetal stages of the development. Moreover, CYP2C8 shows more intensive staining than the other protein monitored in Hofbauer cells in villous stroma. Specific information regarding the exact role of EETs and DHETs functions in a normal placenta is still unknown. Based on CYP epoxygenases and sEH localization and well known information about the functions of placental structures during development, we suggest that these enzymes could play different roles in various cell populations in the placenta. As the placenta is absolutely crucial for prenatal development, arachidonic acid is essential part of human nutrient and CYP epoxygenases expression can be affected by xenobiotics, further investigation of the exact role of CYP epoxygenases, sEH, and their metabolites in normal pregnancy and under pathological conditions is needed.

Immunohistochemistry and immunocytochemistry (ICC) play an irreplaceable role in research and diagnostics. It is well known that antigen retrieval (AR) can, as a technique, have beneficial outcomes on immunohistochemistry results when using formalin-fixed, paraffin-embedded tissue samples. The main purpose of AR is to break protein crosslinks which are formed during formalin fixation. Although AR was originally designed for formalin-fixed, paraffin-embedded samples, the usefulness of AR in ICC has been described in previous studies. Cytologic samples are often fixed in alcohol-based fixatives which does not lead to the formation of crosslinks. Therefore, alcohol-fixed samples can be successfully immunostained without AR. We investigated the effect of heat-induced antigen retrieval (HIAR) on alcohol-fixed HEK293 cell line samples and patient cytologic samples from thyroid gland obtained by fine needle aspiration technique. We compared indirect 2-step ICC staining results performed according to the protocol with or without HIAR in citrate buffer pH 6 for several antibodies. Utilizing HIAR against intracellular antigens has beneficial effects. Therefore, more diluted antibodies can be used for satisfactory results. However, surface antigens were probably damaged by HIAR treatment. We demonstrated evident changes in cell surface topography after HIAR treatment by atomic force microscopy. Staining specificity of patient samples improves and background staining is reduced, allowing higher dilutions of primary antibody. Improving staining specificity is necessary for accurate diagnostics. Although we have shown the beneficial effect of HIAR for immunostaining intracellular antigens, proper staining protocol should be tested on appropriate controls for individual antibodies.

Heat-induced antigen retrieval (HIAR) treatment improves the antigen immunodetection in formalin-fixed, paraffin-embedded tissue samples and it can also improve the detection of intracellular antigens in alcohol-fixed cytological samples, although it could deleteriously impact immunodetection, particularly that of membranous antigens. We examined the differences in cell surface topography on MCF7 cells fixed in methanol/acetone (M/A) or 4% paraformaldehyde (4% PFA), as well as the changes caused by HIAR treatment at three different temperatures (60, 90, and 120°C), using atomic force microscopy. Furthermore, the consequences for immunostaining of five membranous antigens [epidermal growth factor receptor (EGFR), E-cadherin, CD9, CD24, and CD44] were examined. Our results illustrate that while there was no one single optimal immunostaining condition for the tested antibodies, the surface topography could be an important factor in successful staining. Generally, the best conditions for successful immunostaining were M/A fixation with no HIAR treatment, whereas in 4% PFA-fixed cells, HIAR treatment at 120°C was optimal. These conditions showed similarity in cell surface skewness. A correlation factor between successful immunocytochemical staining and the skewness parameter was 0.8000. Our results indicate that the presence of valleys, depressions, scratches, and pits on the cell surface is unfavorable for the successful immunodetection of cell surface antigens.

Fibrates belong to a group of ligands of peroxisome proliferator-activated receptor alpha (PPARα), which play a role in the regulation of CYP epoxygenases and soluble epoxide hydrolase (sEH), key enzymes in the metabolism of biologically highly active epoxyeicosatrienoic acids (EETs). We demonstrated that low doses of fibrates stimulate proliferation of the MCF7 cell line, while high doses suppress it. The increase in cell proliferation was accompanied by an increase in CYP epoxygenases and decrease in sEH levels. The overall level of PPARα remained same after low-dose fibrate stimulation; however, there was a significant shift of the receptor to the cell nucleus. PPARα expression was further demonstrated by immunohistochemistry in both carcinoma and healthy breast tissue samples both in the cytoplasm and in the nuclei. We have also observed higher nuclear PPARα positivity in tumor tissues. Although our results obtained for MCF7 cells suggest the potential role of PPARα in cell proliferation, we did not find an association between nuclear localization of PPARα and the expression of proliferation marker Ki-67 in tumor tissues. The exact role of PPARα in carcinogenesis still remains unclear.

Aims: To determine the frequency of pregnancy terminations due to prenatal congenital heart defect (CHD) and assess the agreement fetal echocardiography (FECHO) and autopsy findings. Methods: The data were retrospectively assessed between 2008 and 2017 in a population of 116 698 live births. The correlations between the FECHO and autopsy findings were classified into five levels of agreement: complete, partial, altered diagnosis, disagreement, and unfeasible autopsy. Results: Totally, 293 CHDs were identified and 49% of families (143/293) decided to terminate the pregnancy. In 1% (2/143) of cases, the autopsy could not be performed, for the other 99% (141/143), the pathologist confirmed the presence of CHDs. Complete agreement between FECHO and autopsy was achieved in 85% (122/143). In 10% (14/143) of cases, the pathologist found minor findings, which were not described in the FECHO. In 4% (5/143) of cases, the pathologist changed the main diagnosis. Conclusion: Altogether, the results indicated that FECHO is a highly sensitive method for the prenatal detection of CHD but is incapable of detecting the complete spectrum of cardiac defects. Autopsies verified the diagnosis, confirmed the overall impairment in the fetus, and provided data for further counselling of the affected family.

Introduction The success of pregnancy depends on the regulation of immunological processes in the placenta. Important mediators of an immune response include pro- and anti-inflammatory interleukins which may be regulated by CYP epoxygenases and their metabolites. The relation between interleukins and CYP epoxygenases expression in human placenta has not yet been studied vastly. Material and methods We investigated the expression patterns of IL-1β and IL-10 in embryonic (n = 8), early foetal (n = 16) and term (n = 7) human placenta tissue by an immunohistochemical method and evaluated the results by Kruskal-Wallis test. The obtained data was correlated using Spearman’s correlation coefficient to our previously published data of CYP epoxygenases expression in the same samples. To confirm that Hofbauer cells express IL-10 and IL-1β as well as CYP2C8 and IL-10 together, and thus there is a relation between proteins of interests, we used multiplex immunofluorescent staining. Results The expression of IL-1β decreased with gestational age in cytotrophoblast, syncytiotrophoblast, as well as in Hofbauer cells whilst IL-10 decreased in cytotrophoblast, remained at the same levels in syncytiotrophoblast and increased in Hofbauer cells. In trophoblast cells, we found a statistically significant positive correlation between the expression of CYP2J2 and CYP2C9 with IL-1β, whereas there was no relation between IL-10 and any of the tested CYP epoxygenases. In Hofbauer cells, we found a significant positive correlation between CYP2C8 and IL-10 and a significant negative correlation between CYP2C8 and IL-1β. Conclusion Our results showed that the exact role and relation of interleukins and CYP epoxygenases and their metabolites is dependent on their respective cellular context. Because of IL-10, IL-1β, as well as HBCs play a role in various pathological conditions, further investigation of the exact role of CYP epoxygenase, interleukins and their relations is needed.

Background and Aims: Macrophages are linked to the initiation of the chronic inflammation believed to underlie the changes taking place in the white fatty tissue of obese people. Both the number of macrophages, but their functional status, play an important role in the development of inflammation. Classically, macrophages are divided into two types: pro-inflammatory (M1) and anti-inflammatory (M2) types, and based on current immunological studies, further views on the functional distribution of macrophages are suggested. In this study, we evaluated the M1 and M2 macrophages ratio in obese subjects with, or without diabetes. To identify all macrophages, we used CD68 expression, while CD204 expression is typically used for the M2 macrophage. Materials and Methods: During bariatric surgery, carried out in obese people with and without type 2 diabetes (T2D), we obtained subcutaneous adipose tissue from the navel and omental adipose tissue. We also obtained the same tissue from people with a physiological range of BMI from a judicial autopsy. Applying immunohistochemical staining anti-CD68 and anti-CD204, we carried out a quantitative evaluation of the number of macrophages. Results: We found CD68+ and CD204+ positive macrophages in perivascular spaces and between fat cells, both isolated and in larger infiltrates. They were also present in so-called "crown-like structures" (CLS) around dying adipocytes. Quantitative analysis showed an increased number of macrophages in all obese patients compared to the control group of non-obese, individuals without T2D. The most striking observation was the macrophage increase in the visceral fatty tissue of diabetics. The number of CD68 and CD204 positive macrophages was statistically significantly smaller in patients without T2D. Conclusion: We demonstrated a significantly greater number of macrophages in visceral adipose tissue, especially in patients with T2D. Our results also show a positive correlation between the presence of T2D and the total number of macrophages; a significantly greater number of macrophages were found in visceral adipose tissue, especially in patients with T2D.

Introduction In this study we detail the effect of different fixation agents and the duration of storage has on the immunohistochemical staining positivity of samples of archival embryonic and fetal tissues. Materials and methods The samples were stained by indirect two-step immunohistochemistry (IHC) method for Ki-67, cyclin A and β-actin. Results Irrespective of the length of tissue archiving, tissue fixation with 10% neutral buffered formalin had better IHC intensity results in all cases when compared to methacarn-fixed tissues. In the case of β-actin, this difference was statistically significant, while differences in Ki-67 and cyclin A were not. The second aspect studied was which effect tissue block archiving duration has on the IHC reactivity. We demonstrated a statistically significant decrease in IHC positivity for all studied antigens between the samples that were archived for 10–19 or 20–45 years, regardless the fixative solution. Conclusion To the best of our knowledge, the influence that the duration of tissue block archiving has on IHC positivity in human embryo and fetal tissue material has not yet been studied. Although the causes of the IHC positivity decline in archived tissue blocks are not well understood, a possible decrease in IHC over time should be considered, particularly in retrospective studies.

The interaction between ABCB1 transporter and its substrates takes place in cell membranes but the available data precludes quantitative analysis of the interaction between transporter and substrate molecules. Further, the amount of transporter is usually expressed as a number of ABCB1 molecules per cell. In contrast, the substrate concentration in cell membranes is estimated by determination of substrate-lipid partition coefficient, as examples. In this study, we demonstrate an approach, which enables us to estimate the concentration of ABCB1 molecules within plasma membranes. For this purpose, human leukemia K562 cells with varying expression levels of ABCB1 were used: drug selected K562/Dox and K562/HHT cells with very high transporter expression, and K562/DoxDR2, K562/DoxDR1, and K562/DoxDR05 cells with gradually decreased expression of ABCB1 derived from K562/Dox cells using RNA interference technology. First, we determined the absolute amount of ABCB1 in cell lysates using immunoblotting and recombinant ABCB1 as a standard. We then determined the relative portion of transporter residing in the plasma membrane using immunohistochemistry in nonpermeabilized and permeabilized cells. These results enabled us to estimate the concentration of ABCB1 in the plasma membrane in resistant cells. The ABCB1 concentrations in the plasma membrane of drug selected K562/Dox and K562/HHT cells containing the highest amount of transporter reached millimolar levels. Concentrations of ABCB1 in the plasma membrane of resistant K562/DoxDR2, K562/DoxDR1, and K562/DoxDR05 cells with lower transporter expression were proportionally decreased.

CYP epoxygenases metabolize arachidonic acid into four regioisomers of epoxyeicosatrienoic acids (EETs) which are hydrolysed into their corresponding diols by soluble epoxide hydrolase (sEH). EETs are very biologically active molecules. They promote proliferation and inhibit apoptosis as well as numerous other functions within organisms. Peroxisome proliferator-activated receptor α (PPARα) play role in regulation of CYP epoxygenases and sEH. PPARα is the ligand-dependent transcriptional factor which is activated by various compounds, including fibrates. The latter are widely used in clinical practice. This study investigates the changes in expression of CYP2C8, CYP2J2, and sEH in HEK293, HepG2, and HT-29 cell lines after fibrate treatment using two different incubation times. The results demonstrate that the effect of fibrates on arachidonic acid-metabolizing enzymes expression is concentration-dependent. Although CYP2C8 expression is downregulated by the fibrates treatment, the results reveal that changes in CYP2J2/sEH ratio are closely associated with cell proliferation and could explain the differing proliferation response of cells to different concentrations of fibrates.

Soluble epoxide hydrolase (sEH) converts highly active epoxyeicosatrienoic acids (EETs) generated by cytochrome P450 (CYP) epoxygenases from arachidonic acid to less active dihydroxyeicosatrienoic acids. Because of the role of EETs in processes potentially relevant to the development of organisms, EETs could be suggested as potential morphogens. Unfortunately, only little is known about sEH expression during human intrauterine development (IUD). We investigated the spatio-temporal expression pattern of sEH in human embryonic/foetal intestines, liver and kidney from the 6th to the 20th week of IUD by two-step immunohistochemistry. sEH was expressed during the whole tested period of prenatal development and its level of expression remained more or less the same during the estimated period of IUD. Distribution of CYP epoxygenases and sEH in the intestinal epithelium and the nephrogenic zone of the kidney suggests an influence of EETs on cell proliferation and differentiation and, consequently, on the development of intestines and kidney. Thus, alterations in the strict spatio-temporal pattern of expression of CYP epoxygenases and/or sEH during human prenatal development by xenobiotics could have a harmful impact for developing organisms.

Peroxisome proliferator-activated receptor α (PPARα) is a ligand-dependent transcription factor which is activated by various endogenous as well as exogenous compounds. It is involved in the regulation of a variety of biological processes, such as nutrient metabolism, energy homoeostasis, immunological response and xenobiotic metabolism. Little is known about its expression during human prenatal development. We examined the spatio-temporal expression pattern of PPARα in human embryonic/foetal intestines, liver and kidney from the 5th to 20th week of prenatal life by indirect two-step immunohistochemistry. PPARα expression can already be detected in the early stages of prenatal development; as early as the 7th week of intrauterine development (IUD) in the intestines, 5th week of IUD in the liver and 6th week of IUD in the kidney. We found age-dependent changes in the PPARα expression pattern in the intestines and kidney. These events occur approximately at the commencement of function of these organs. In the intestines, we detected an obvious change of the PPARα expression pattern along the crypt-villous axis in the 11th week of IUD. In the kidney, the most apparent change was increased expression of PPARα in glomeruli in the 12th week of IUD. Moreover, in the liver, we detected a strong positivity in part of the developing blood elements. Information about the spatio-temporal expression pattern of PPARα could be the first step in evaluating the potential harmful impact of a wide range of environmental or pharmaceutical compounds which serve as PPARα ligands on the developing human organism.

Background Fibrates are widely used hypolipidemic drugs, which serve as ligand of peroxisome proliferator-activated receptor α (PPARα). Recently, they have also been considered as potential anticancer agents. We studied effect of fibrates treatment on cell proliferation, expression of CYP2J2 and concomitant changes in expression of cell cycle regulatory proteins in three different human cell lines: HEK293, HepG2, and HT-29. Methods We used WST-1 viability test, western blot and immunocytochemistry for detection of proteins of interests and analysis of cell cycle. Results Our results showed that at lower concentrations of all tested fibrates, viability of all tested cell lines is increased, whereas at higher concentrations, repression is apparent. Unfortunately, the viability of tested cells is predominantly increased in a range of concentration which is reached in patient plasma. This phenomenon is accompanyed by elevation of CYP2J2, increased number of cyclin E-positive cells and decreased number of Cdc25A-positive cells in all tested cell lines, and elevated cyclin A expression in HepG2 and HT-29. These changes are concentration-dependent. We suppose that increased level of CYP2J2 could explain enhanced cell proliferation in lower concentration of fibrates. Conclusion Based on our results, we suggested there is no anti-cancer effect of fibrates in tested carcinoma cell lines. Electronic supplementary material The online version of this article (doi:10.1186/s12944-016-0335-z) contains supplementary material, which is available to authorized users.

Embryonic and tumour cells are able to protect themselves against various harmful compounds. In human pathology, this phenomenon exists in the form of multidrug resistance (MDR) that significantly deteriorates success of anticancer treatment. Cytochromes P450 (CYPs) play one of the key roles in the xenobiotic metabolism. CYP expression could contribute to resistance of cancer cells to chemotherapy. CYP epoxygenases (CYP2C and CYP2J) metabolize about 20% of clinically important drugs. Besides of drug metabolism, CYP epoxygenases and their metabolites play important role in embryos, normal body function, and tumors. They participate in angiogenesis, mitogenesis, and cell signaling. It was found that CYP epoxygenases are affected by peroxisome proliferator-activated receptorα(PPARα). Based on the results of current studies, we assume that PPARs ligands may regulate CYP2C and CYP2J and in some extent they may contribute to overcoming of MDR in patients with different types of tumours.