The influence of protein-flavonoid interactions on protein digestibility in vitro and the antioxidant quality of breads enriched with onion skin

Different types of breads enriched with onion skin were studied. The objectives were twofold: to show and examine protein-phenolic interactions and to discuss results concerning phenolic content, antioxidant activity and protein digestibility in the light of in vitro bioaccessibility. Phenolic contents and antiradical abilities were linked with the level of onion skin supplement however, the amounts determined were significantly lower than expected. Fortification influenced protein digestibility (a reduction from 78.4% for control breads to 55% for breads with a 4% supplement). Electrophoretic and chromatographic studies showed the presence of indigestible protein-flavonoid complexes - with molecular weights about 25 kDa and 14.5 kDa; however, the reduction of free amino group levels and the increase in chromatogram areas suggest that flavonoids also bind to other bread proteins. The interaction of phenolics with proteins affects antioxidant efficacy and protein digestibility; thus, they have multiple effects on food quality and pro-health properties.

Quality and antioxidant properties of breads enriched with dry onion (Allium cepa L.) skin

The aim of the study was to investigate the effect on the antioxidant properties and sensory value of bread of adding ground onion skin (OS). For a determination of bioaccessibility and bioavailability in vitro the human gastrointestinal tract model was used. OS contained mastication-extractable quercetin (4.6 mg/g). Quercetin from OS was highly bioaccessible during in vitro conditions, but only approximately 4% of quercetin released during simulated digestion was bioavailable in vitro. The antioxidant potential of bread with OS was significantly higher than the activity noted in the control. In particular, OS addition significantly fortificated bread with bioaccessible lipid oxidation preventers and compounds with reducing and chelating abilities. The 2-3% OS addition caused significant improvement of antioxidant abilities (further increases in the OS supplement did not increase the activity of bread). Sensory evaluation showed that replacement of wheat flour in bread with up to 3% OS powder gave satisfactory consumer acceptability.

The role of connexins in prostate cancer promotion and progression

Prostate cancer is a prevalent disease that is characterized by a presumably long latency period and a moderate propensity to metastasize. Although a range of mechanisms have been implicated in prostate carcinogenesis, the factors determining the initiation of metastasis remain obscure. The synchronized function of prostate cells depends on their metabolic and electrical coupling; disturbance of these functions has long been suggested to be integral to prostate carcinogenesis. However, although connexins form intercellular channels involved in gap-junction-mediated intercellular coupling (GJIC), whether these proteins also have GJIC-independent roles in cancer progression and metastasis remains a matter of debate. Some data indicate a correlation between connexin expression and the invasive potential of prostate cancer cells, which points to stage-specific functions of connexins during prostate cancer development. For example, restoration of connexin expression seems to be crucial for the formation of invasive cell subsets within heterogeneous prostate cancer cell populations that have undergone aberrant differentiation. Consequently, the clinical application of therapeutic and prophylactic approaches focused on the modulation of connexin expression in prostate cancer cells should be reconsidered.

Usnic acid and atranorin exert selective cytostatic and anti-invasive effects on human prostate and melanoma cancer cells

OBJECTIVES AND METHODS

Lichens are an interesting source of potential anti-tumor compounds, among which usnic acid and atranorin seem to be the most promising, but their impact on invasive potential of tumor cells has not yet been comprehensively addressed. The aim of the study was focused on the impact of the two lichen metabolites, on the viability (by Trypan blue test and fluoresceine diacetate and ethidium bromide assay), proliferation (cell counting in a Bürker's chamber), apoptosis (flow cytometry analysis and Western blot) and motile activity (cell movement recording and image analysis) and actin cytoskeleton organization (immunofluorescent staining) of melanoma HTB-140, prostate cancers DU-145 and PC-3, normal human skin fibroblasts and prostate epithelial PNT2 cells, with special emphasis to their selectivity and versatility.

RESULTS

Both compounds exerted strong inhibitory effects on cancer cell proliferation, migration and actin cytoskeleton organization, while their effect on apoptosis process was less relevant. The impact of usnic acid on the examined cancer cells was found more efficient in comparison to atranorin. Also, selective effect of both agents on tumor cells was observed.

SIGNIFICANCE

The ability of usnic acid and atranorin to inhibit cancer cells motility may have future implications for development of new therapeutic strategies targeted at the interference with the metastatic cascade.

Functional links between Snail-1 and Cx43 account for the recruitment of Cx43-positive cells into the invasive front of prostate cancer

Suppressive function of connexin(Cx)43 in carcinogenesis was recently contested by reports that showed a multifaceted function of Cx43 in cancer progression. These studies did not attempt to model the dynamics of intratumoral heterogeneity involved in the metastatic cascade. An unorthodox look at the phenotypic heterogeneity of prostate cancer cells in vitro enabled us to identify links between Cx43 functions and Snail-1-regulated functional speciation of invasive cells. Incomplete Snail-1-dependent phenotypic shifts accounted for the formation of phenotypically stable subclones of AT-2 cells. These subclones showed diverse predilection for invasive behavior. High Snail-1 and Cx43 levels accompanied high motility and nanomechanical elasticity of the fibroblastoid AT-2_Fi2 subclone, which determined its considerable invasiveness. Transforming growth factor-β and ectopic Snail-1 overexpression induced invasiveness and Cx43 expression in epithelioid AT-2 subclones and DU-145 cells. Functional links between Snail-1 function and Cx43 expression were confirmed by Cx43 downregulation and phenotypic shifts in AT-2_Fi2, DU-145 and MAT-LyLu cells upon Snail-1 silencing. Corresponding morphological changes and Snail-1 downregulation were seen upon Cx43 silencing in AT-2_Fi2 cells. This indicates that feedback loops between both proteins regulate cell invasive behavior. We demonstrate that Cx43 may differentially predispose prostate cancer cells for invasion in a coupling-dependent and coupling-independent manner. When extrapolated to in vivo conditions, these data show the complexity of Cx43 functions during the metastatic cascade of prostate cancer. They may explain how Cx43 confers a selective advantage during cooperative invasion of clonally evolving, invasive prostate cancer cell subpopulations.

Multidirectional effects of triterpene saponins on cancer cells - mini-review of in vitro studies

Triterpene saponins (saponosides) are found in a variety of higher plants and display a wide range of pharmacological activities, including expectorant, anti-inflamatory, vasoprotective, gastroprotective and antimicrobial properties. Recently, a potential anticancer activity of saponins has been suggested by their cytotoxic, cytostatic, pro-apoptotic and anti-invasive effects. At high concentrations (more than 100 µM) saponins exert cytotoxic and haemolytic effects via permeabilization of the cell membranes. Noteworthy, the inhibition of cancer cell proliferation, the induction of apoptosis and attenuation of cell invasiveness is observed in the presence of low saponin concentrations. Saponins might affect the expression of genes associated with malignancy. These alterations are directly related to the invasive phenotype of cancer cells and depend on "cellular context". It illustrates the relationships between the action of saponins, and the momentary genomic/proteomic status of cancer cells. Here, we discuss the hallmarks of anti-cancer activity of saponins with the particular emphasis on anti-invasive effect of diverse groups of saponins that have been investigated in relation to tumor therapy.

Carfilzomib, lenalidomide, and dexamethasone or lenalidomide alone as maintenance therapy after autologous stem-cell transplantation in patients with multiple myeloma (ATLAS): interim analysis of a randomised, open-label, phase 3 trial

BACKGROUND

Lenalidomide is a cornerstone of maintenance therapy in patients with newly diagnosed multiple myeloma after autologous stem-cell transplantation. We aimed to compare the efficacy and safety of maintenance therapy with carfilzomib, lenalidomide, and dexamethasone versus lenalidomide alone in this patient population.

METHODS

This study is an interim analysis of ATLAS, which is an investigator-initiated, multicentre, open-label, randomised, phase 3 trial in 12 academic and clinical centres in the USA and Poland. Participants were aged 18 years or older with newly diagnosed multiple myeloma, completed any type of induction and had stable disease or better, autologous stem-cell transplantation within 100 days, initiated induction 12 months before enrolment, and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients were randomly assigned (1:1) using permuted blocks of sizes 4 and 6 and a web-based system to receive up to 36 cycles of carfilzomib, lenalidomide, and dexamethasone (28-day cycles of carfilzomib 20 mg/m2 administered intravenously in cycle one on days 1 and 2 then 36 mg/m2 on days 1, 2, 8, 9, 15, and 16 in cycles one to four and 36 mg/m2 on days 1, 2, 15, and 16 from cycle five up to 36 [per protocol]; lenalidomide 25 mg administered orally on days 1-21; and dexamethasone 20 mg administered orally on days 1, 8, 15, and 22) or lenalidomide alone (10 mg administered orally for the first three cycles and then at the best tolerated dose [≤15 mg for 28 days in 28-day cycles]) until disease progression or unacceptable toxicity as maintenance therapy. After 36 cycles, patients in both treatment groups received lenalidomide maintenance. Randomisation was stratified by response to previous treatment, cytogenetic risk factors, and country. Investigators and patients were not masked to treatment allocation. Patients in the carfilzomib, lenalidomide, and dexamethasone group with no detectable minimal residual disease after cycle six (as per International Myeloma Working Group criteria) and standard-risk cytogenetics were switched to lenalidomide maintenance as of cycle nine. The primary endpoint was progression-free survival in the intention-to-treat population (defined as all randomly assigned patients). Safety was analysed in all randomly assigned patients who received at least one dose of study treatment. This unplanned interim analysis was triggered by the occurrence of 59 (61%) of the expected 96 events for the primary analysis and the results are considered preliminary. This trial is registered with ClinicalTrials.gov, NCT02659293 (active, not recruiting) and EudraCT, 2015-002380-42.

FINDINGS

Between June 10, 2016, and Oct 21, 2020, 180 patients were randomly assigned to receive either carfilzomib, lenalidomide, and dexamethasone (n=93) or lenalidomide alone (n=87; intention-to-treat population). The median age of patients was 59·0 years (IQR 49·0-63·0); 84 (47%) patients were female and 96 (53%) were male. With a median follow-up of 33·8 months (IQR 20·9-42·9), median progression-free survival was 59·1 months (95% CI 54·8-not estimable) in the carfilzomib, lenalidomide, and dexamethasone group versus 41·4 months (33·2-65·4) in the lenalidomide group (hazard ratio 0·51 [95% CI 0·31-0·86]; p=0·012). The most common grade 3 and 4 adverse events were neutropenia (44 [48%] in the carfilzomib, lenalidomide, and dexamethasone group vs 52 [60%] in the lenalidomide group), thrombocytopenia (12 [13%] vs six [7%]), and lower respiratory tract infections (seven [8%] vs one [1%]). Serious adverse events were reported in 28 (30%) patients in the carfilzomib, lenalidomide, and dexamethasone group and 19 (22%) in the lenalidomide group. One treatment-related adverse event led to death (respiratory failure due to severe pneumonia) in the carfilzomib, lenalidomide, and dexamethasone group.

INTERPRETATION

This interim analysis provides support for considering carfilzomib, lenalidomide, and dexamethasone therapy in patients with newly diagnosed multiple myeloma who completed any induction regimen followed by autologous stem-cell transplantation, which requires confirmation after longer follow-up of this ongoing phase 3 trial.

FUNDING

Amgen and Celgene (Bristol Myers Squibb).

Therapeutic potential of monoterpene α-thujone, the main compound of Thuja occidentalis L. essential oil, against malignant glioblastoma multiforme cells in vitro

Thuja occidentalis L. is indigenous for Northern America and commonly cultivated in Europe. Raw materials obtained from this tree are widely applied in the ethnomedicine and phytotherapy of numerous ailments, incl. scurvy, cystitis, rheumatism and cancer. Despite wide medicinal applications of Thuja occidentalis, still little is known on its therapeutic potential in tumor treatment. α-thujone is the main component of Thuja occidentalis essential oil, which has been suggested to possess anti-tumor activities. This monoterpene easily penetrates the blood-brain barrier. Therefore, we examined its effects on the malignancy of glioblastoma multiforme (GBM) cells, with the special emphasis on the mechanisms of its effect on cell viability and invasiveness. α-thujone exerted the attenuating effect on the viability and proliferation of GBM cells when administered at the concentrations between 100 and 500 μg/ml (660 μM - 3.2 mM). This effect was correlated with the induction of apoptosis in GBM cell populations and with considerable inhibition of GBM cells motility. Mechanistic analyses demonstrated the induction of oxidative stress and autophagy in α-thujone-treated tumor cells, whereas normal astrocytes displayed considerably lower sensitivity to α-thujone. Our observations demonstrate that α-thujone exerts pro-apoptotic and anti-invasive effects on GBM cells. They confirm the potential of α-thujone for the treatment of glioblastoma multiforme.

Connexin43 Controls the Myofibroblastic Differentiation of Bronchial Fibroblasts from Patients with Asthma

Pathologic accumulation of myofibroblasts in asthmatic bronchi is regulated by extrinsic stimuli and by the intrinsic susceptibility of bronchial fibroblasts to transforming growth factor-β (TGF-β). The specific function of gap junctions and connexins in this process has remained unknown. Here, we investigated the role of connexin43 (Cx43) in TGF-β-induced myofibroblastic differentiation of fibroblasts derived from bronchoscopic biopsy specimens of patients with asthma and donors without asthma. Asthmatic fibroblasts expressed considerably higher levels of Cx43 and were more susceptible to TGF-β₁-induced myofibroblastic differentiation than were their nonasthmatic counterparts. TGF-β₁ efficiently up-regulated Cx43 levels and activated the canonical Smad pathway in asthmatic cells. Ectopic Cx43 expression in nonasthmatic (Cx43_low) fibroblasts increased their predilection to TGF-β₁-induced Smad2 activation and fibroblast-myofibroblast transition. Transient Cx43 silencing in asthmatic (Cx43^high) fibroblasts by Cx43 small interfering RNA attenuated the TGF-β₁-triggered Smad2 activation and myofibroblast formation. Direct interactions of Smad2 and Cx43 with β-tubulin were demonstrated by co-immunoprecipitation assay, whereas the sensitivity of these interactions to TGF-β₁ signaling was confirmed by Förster Resonance Energy Transfer analyses. Furthermore, inhibition of the TGF-β₁/Smad pathway attenuated TGF-β₁-triggered Cx43 up-regulation and myofibroblast differentiation of asthmatic fibroblasts. Chemical inhibition of gap junctional intercellular communication with 18 α-glycyrrhetinic acid did not affect the initiation of fibroblast-myofibroblast transition in asthmatic fibroblasts but interfered with the maintenance of their myofibroblastic phenotype. Collectively, our data identified Cx43 as a new player in the feedback mechanism regulating TGF-β₁/Smad-dependent differentiation of bronchial fibroblasts. Thus, our observations point to Cx43 as a novel profibrotic factor in asthma progression.

Fenofibrate enhances barrier function of endothelial continuum within the metastatic niche of prostate cancer cells

OBJECTIVE

Extravasation of circulating cancer cells is an important step of the metastatic cascade and a potential target for anti-cancer strategies based on vasoprotective drugs. Reports on anti-cancer effects of fenofibrate (FF) prompted us to analyze its influence on the endothelial barrier function during prostate cancer cell diapedesis.

RESEARCH DESIGN AND METHODS

In vitro co-cultures of endothelial cells with cancer cells imitate the 'metastatic niche' in vivo. We qualitatively and quantitatively estimated the effect of 25 μM FF on the events which accompany prostate carcinoma cell diapedesis, with the special emphasis on endothelial cell mobilization.

RESULTS

Fenofibrate attenuated cancer cell diapedesis via augmenting endothelial cell adhesion to the substratum rather than through the effect on intercellular communication networks within the metastatic niche. The inhibition of endothelial cell motility was accompanied by the activation of PPARα-dependent and PPARα-independent reactive oxygen species signaling, Akt and focal adhesion kinase (FAK) phosphorylation, in the absence of cytotoxic effects in endothelial cells.

CONCLUSIONS

Fenofibrate reduces endothelial cell susceptibility to the paracrine signals received from prostate carcinoma cells, thus inhibiting endothelial cell mobilization and reducing paracellular permeability of endothelium in the metastatic niche. Our data provide a mechanistic rationale for extending the clinical use of FF and for the combination of this well tolerated vasoactive drug with the existing multidrug regimens used in prostate cancer therapy.

Apigenin inhibits TGF-β1 induced fibroblast-to-myofibroblast transition in human lung fibroblast populations

BACKGROUND

Flavonoids are dietary plant compounds suspected to reduce the incidence of chronic diseases in several regions of the world. Due to anti-allergic and anti-inflammatory activities, apigenin (4',5,7,-trihydroxyflavone) is thought to interfere with crucial events in the pathomechanism of asthma. However, the effect of apigenin on TGF-β-induced fibroblast-to-myofibroblast transition (FMT) in human lung fibroblast populations, a key event in asthma progression, has not yet been addressed.

METHODS

Primary human bronchial fibroblasts (HBFs) propagated from ex vivo bronchial biopsies derived from patients with diagnosed asthma and human embryonic lung IMR-90 fibroblasts were cultured in vitro and treated with TGF-β1 and apigenin. The myofibroblast fraction in fibroblast populations was evaluated by immunocytochemistry. Expression of α-smooth muscle actin (α-SMA) and tenascin C were assessed at the mRNA and protein level by real-time RT-PCR and immunoblotting, respectively. Additionally, proliferation and viability tests and time lapse-monitoring of movement of individual HBFs and IMR-90 cells were evaluated.

RESULTS

We show that apigenin attenuates TGF-β1-induced FMT in cultures of HBFs, and the magnitude of this attenuation was found to be similar to that observed in the established cell line of lung IMR-90 fibroblasts. Notably, FMT inhibition was observed at low (≈10 μM), non-cytotoxic and non-cytostatic apigenin concentrations and could be correlated with the inhibition of α-SMA and tenascin C expression in HBFs at the mRNA level.

CONCLUSIONS

Our data are the first to demonstrate that apigenin inhibits the TGF-β1-induced expansion of hyper-contractile, α-smooth muscle actin - positive myofibroblasts within populations of HBFs derived from asthmatic patients. They also indicate the possible interference of apigenin with bronchial wall remodeling during the asthmatic process in vivo.

Constitutional mutations of the CHEK2 gene are a risk factor for MDS, but not for de novo AML

CHEK2 plays a key role in cellular response to DNA damage, and also in regulation of mitosis and maintenance of chromosomal stability. In patients newly diagnosed with myelodysplastic syndrome (MDS, n = 107) or acute myeloid leukemia (AML, n = 117) congenital CHEK2 mutations (c.444 + 1G > A, c.1100delC, del5395, p.I157 T) were tested by PCR and sequencing analysis. The karyotype of bone marrow cells of each patient was assessed at disease diagnosis using classical cytogenetic methods and fluorescence in situ hybridization. The CHEK2 mutations were strongly associated with the risk of MDS (p < 0.0001) but not with the risk of de novo AML (p = 0.798). In CHEK2-positive MDS patients, two times higher frequency of aberrant karyotypes than in CHEK2-negative patients was found (71% vs. 37%, p = 0.015). In CHEK2-positive patients with cytogenetic abnormalities, subtypes of MDS: refractory anemia with excess blasts-1 or 2, associated with unfavorable disease prognosis, were diagnosed two times more often than in CHEK2-negative cases with aberrations (78% vs. 44%). In conclusion, the congenital CHEK2 inactivation is strongly associated with the risk of MDS and with a poorer prognosis of the disease. However, the chromosomal instability in AML is not correlated with the hereditary dysfunction of CHEK2.

Transition of asthmatic bronchial fibroblasts to myofibroblasts is inhibited by cell-cell contacts

The role of airway wall remodelling in bronchial asthma is well established. Myofibroblasts, the cells displaying features intermediate between fibroblasts and smooth muscle cells, are involved in this process but the mechanism of myofibroblasts activation in the onset of the disease remains obscure. Myofibroblasts can differentiate from various cell types, including resident fibroblasts, and the fibroblasts to myofibroblasts transition (FMT) can be reproduced in vitro. We aimed to investigate the process of FMT in human bronchial fibroblasts (HBF) derived from non-asthmatic (n = 7) and asthmatic (n = 7) subjects. We also tested whether cell-cell contacts affect FMT by using N-cadherin blocking antibody. HBF plated in low or high cell density were treated with TGF-β(1) up to one week to induce FMT. The percentage of myofibroblsts was counted and expression of α-smooth muscle actin was evaluated by cytoimmunofluorescence, flow cytometry and immunobloting. We demonstrated that the intensity of FMT induced by TGF-β(1)in vitro was strongly enhanced in asthmatic as compared to non-asthmatic HBF populations. This process was facilitated by low cell plating density in both groups of cultures. Furthermore, we proved that neither HBF-conditioned medium nor growth arrest in G(0)/G(1) phase of cell cycle could stop the TGF-β(1)-induced FMT in asthmatic cell populations. However, even in sparse asthmatic HBF, the blocking of N-cadherin resulted in the inhibition of FMT. Our findings show for the first time that the initial absence or an induced loss of cell-cell adhesions in asthmatic HBF populations is important for the completion of FMT.

Fenofibrate Augments the Sensitivity of Drug-Resistant Prostate Cancer Cells to Docetaxel

Metronomic agents reduce the effective doses and adverse effects of cytostatics in cancer chemotherapy. Therefore, they can enhance the treatment efficiency of drug-resistant cancers. Cytostatic and anti-angiogenic effects of fenofibrate (FF) suggest that it can be used for the metronomic chemotherapy of drug-resistant prostate tumors. To estimate the effect of FF on the drug-resistance of prostate cancer cells, we compared the reactions of naïve and drug-resistant cells to the combined treatment with docetaxel (DCX)/mitoxantrone (MTX) and FF. FF sensitized drug-resistant DU145 and PC3 cells to DCX and MTX, as illustrated by their reduced viability and invasive potential observed in the presence of DCX/MTX and FF. The synergy of the cytostatic activities of both agents was accompanied by the inactivation of P-gp-dependent efflux, dysfunction of the microtubular system, and induction of polyploidy in DCX-resistant cells. Chemical inhibition of PPARα- and reactive oxygen species (ROS)-dependent pathways by GW6471 and N-acetyl-L-cysteine, respectively, had no effect on cell sensitivity to combined DCX/FF treatment. Instead, we observed the signs of adenosine triphosphate (ATP) deficit and autophagy in DCX/FF-treated drug-resistant cells. Furthermore, the cells that had been permanently propagated under DCX- and DCX/FF-induced stress did not acquire DCX/FF-resistance. Instead, relatively slow proliferation of DCX-resistant cells was efficiently inhibited by FF. Collectively, our observations show that FF reduces the effective doses of DCX by interfering with the drug resistance and energy metabolism of prostate cancer cells. Concomitantly, it impairs the chemotherapy-induced microevolution and expansion of DCX/FF-resistant cells. Therefore, FF can be applied as a metronomic agent to enhance the efficiency of palliative chemotherapy of prostate cancer.

Fenofibrate Reduces the Asthma-Related Fibroblast-To-Myofibroblast Transition by TGF-Β/Smad2/3 Signaling Attenuation and Connexin 43-Dependent Phenotype Destabilization

The activation of human bronchial fibroblasts by transforming growth factor-β₁ (TGF-β₁) leads to the formation of highly contractile myofibroblasts in the process of the fibroblast–myofibroblast transition (FMT). This process is crucial for subepithelial fibrosis and bronchial wall remodeling in asthma. However, this process evades current therapeutic asthma treatment strategies. Since our previous studies showed the attenuation of the TGF-β₁-induced FMT in response to lipid-lowering agents (e.g., statins), we were interested to see whether a corresponding effect could be obtained upon administration of hypolipidemic agents. In this study, we investigated the effect of fenofibrate on FMT efficiency in populations of bronchial fibroblasts derived from asthmatic patients. Fenofibrate exerted a dose-dependent inhibitory effect on the FMT, even though it did not efficiently affect the expression of α-smooth muscle actin (α-SMA; marker of myofibroblasts); however, it considerably reduced its incorporation into stress fibers through connexin 43 regulation. This effect was accompanied by disturbances in the actin cytoskeleton architecture, impairments in the maturation of focal adhesions, and the fenofibrate-induced deactivation of TGF-β₁/Smad2/3 signaling. These data suggest that fenofibrate interferes with myofibroblastic differentiation during asthma-related subepithelial fibrosis. The data indicate the potential application of fenofibrate in the therapy and prevention of bronchial remodeling during the asthmatic process.

Heart non-specific effector CD4+ T cells protect from postinflammatory fibrosis and cardiac dysfunction in experimental autoimmune myocarditis

Heart-specific CD4⁺ T cells have been implicated in development and progression of myocarditis in mice and in humans. Here, using mouse models of experimental autoimmune myocarditis (EAM) we investigated the role of heart non-specific CD4⁺ T cells in the progression of the disease. Heart non-specific CD4⁺ T cells were obtained from DO11.10 mice expressing transgenic T cell receptor recognizing chicken ovalbumin. We found that heart infiltrating CD4⁺ T cells expressed exclusively effector (T_eff) phenotype in the EAM model and in hearts of patients with lymphocytic myocarditis. Adoptive transfer experiments showed that while heart-specific T_eff infiltrated the heart shortly after injection, heart non-specific T_eff effectively accumulated during myocarditis and became the major heart-infiltrating CD4⁺ T cell subset at later stage. Restimulation of co-cultured heart-specific and heart non-specific CD4⁺ T cells with alpha-myosin heavy chain antigen showed mainly Th1/Th17 response for heart-specific T_eff and up-regulation of a distinct set of extracellular signalling molecules in heart non-specific T_eff. Adoptive transfer of heart non-specific T_eff in mice with myocarditis did not affect inflammation severity at the peak of disease, but protected the heart from adverse post-inflammatory fibrotic remodelling and cardiac dysfunction at later stages of disease. Furthermore, mouse and human T_eff stimulated in vitro with common gamma cytokines suppressed expression of profibrotic genes, reduced amount of α-smooth muscle actin filaments and decreased contraction of cardiac fibroblasts. In this study, we provided a proof-of-concept that heart non-specific T_eff cells could effectively contribute to myocarditis and protect the heart from the dilated cardiomyopathy outcome.

Triterpene saponosides from Lysimachia ciliata differentially attenuate invasive potential of prostate cancer cells

Neither androgen ablation nor chemotherapeutic agents are effective in reducing the risk of prostate cancer progression. On the other hand, multifaceted effects of phytochemicals, such as triterpene saponins, on cancer cells have been suggested. A promising safety and tolerability profile indicate their possible application in the treatment of advanced prostate cancers. We analyzed the specificity, selectivity and versatility of desglucoanagalloside B effects on human prostate cancer cells derived from prostate cancer metastases to brain (DU-145 cells) and bone (PC-3 cells). Prominent growth arrest and apoptotic response of both cell types was observed in the presence of sub-micromolar desglucoanagalloside B concentrations. This was accompanied by cytochrome c release and caspase 3/7 activation. A relatively low cytostatic and pro-apoptotic response of cancer cells to a desglucoanagalloside B analog, anagallosaponin IV, illustrated the specificity of the effects of desglucoanagalloside B, whereas the low sensitivity of normal prostate PNT2 cells to desglucoanagalloside B showed the selectivity of its action. Inhibition of cancer cell motility was observed in the presence of both saponins, however only desglucoanagalloside B attenuated cancer cell invasive potential, predominantly through an effect on cell elastic properties. These data demonstrate the versatility of its effects on prostate cancer cells. In contrast to PNT2 cells, cancer cells tested in this study were relatively resistant to mitoxantrone. The multifaceted action of desglucoanagalloside B on basic cellular traits, crucial for prostate cancer progression, opens perspectives for elaboration of combined palliative therapies and new prostate cancer prophylaxis regimens.

Connexin43high prostate cancer cells induce endothelial connexin43 up-regulation through the activation of intercellular ERK1/2-dependent signaling axis

Connexin(Cx)43 regulates the invasive potential of prostate cancer cells and participates in their extravasation. To address the role of endothelial Cx43 in this process, we analyzed Cx43 regulation in human umbilical vein endothelial cells in the proximity of Cx43^high (DU-145 and MAT-LyLu) and Cx43^low prostate cancer cells (PC-3 and AT-2). Endothelial Cx43 up-regulation was observed during the diapedesis of DU-145 and MAT-LyLu cells. This process was attenuated by transient Cx43 silencing in cancer cells and by chemical inhibition of ERK1/2-dependent signaling in endothelial cells. Cx43 expression in endothelial cells was insensitive to the inhibition of gap junctional intercellular coupling between Cx43^high prostate cancer and endothelial cells by 18α-glycyrrhetinic acid. Instead, endothelial Cx43 up-regulation was correlated with the local contraction of endothelial cells and with their activation in the proximity of Cx43^high DU-145 and MAT-LyLu cells. It was also sensitive to pro-inflammatory factors secreted by peripheral blood monocytes, such as TNFα. In contrast to Cx43^low AT-2 cells, Cx43^low PC-3 cells produced angioactive factors that locally activated the endothelial cells in the absence of endothelial Cx43 up-regulation. Collectively, these data show that Cx43^low and Cx43^high prostate cancer cells can adapt discrete, Cx43-independent and Cx43-dependent strategies of diapedesis. Our observations identify a novel strategy of prostate cancer cell diapedesis, which depends on the activation of intercellular Cx43/ERK1/2/Cx43 signaling axis at the interfaces between Cx43^high prostate cancer and endothelial cells.

Connexin-dependent intercellular stress signaling in tissue homeostasis and tumor development

Cellular stress responses determine tissue development, homeostasis and pathogenesis. Paracrine signaling, exchange of mechanical stimuli and intercellular transfer of small metabolites via connexin-built gap junctional channels are involved in the cellular stress detection and propagation of stress stimuli in multicellular networks. Cellular stress responses are also regulated through the activity of unpaired connexons (hemichannels) and via the intracellular interference of connexins with the cell cycle and pro-apoptotic machinery. Therefore, connexins are considered as multidirectional transmitters of the "outside-in" and "inside-out" stress signaling that are crucial for tissue homeostasis, regeneration and pathology. In particular, the disturbance of connexin function during the multi-stage process of tumor development leads to abnormal reactions of tumor cells to stress stimuli. In this review, we outline the current knowledge on the multidirectional role of connexins in the detection of stress signals. We also discuss the role of connexin-mediated intercellular transmittance of stress signals in tumour promotion, progression and metastatic cascade.

HIGHLIGHTS

1. Connexins and gap junctions protect cells from the microenvironmental stress and are involved in propagation and intracellular processing of stress signals. 2. The quality and quantity of stress stimuli, which may lead to cell adaptation or death by apoptosis, is determined by intrinsic properties of connexins and the cell phenotype. 3. Connexin deficiency increases the resistance of tumor cells to the "outside-in" stress signaling. 4. The connexin-mediated "inside-out" stress signaling participates in tumor cell invasion during the metastatic cascade.

Fenofibrate attenuates contact-stimulated cell motility and gap junctional coupling in DU-145 human prostate cancer cell populations

In the present study, we investigated the effects of fenofibrate on the invasive potential of DU-145 human prostate cancer cells in the context of gap junctional intercellular coupling and the formation of reactive oxygen species. Time-lapse analyses of cell motility, accompanied by tests of cell viability, membrane microviscosity, reactive oxygen species accumulation and the function of gap junctional protein connexin 43 were performed in monolayer cultures of DU-145 cells following fenofibrate administration. Fenofibrate inhibited the motility of DU-145 cells and attenuated gap junctional intercellular coupling in a manner independent of its effects on cell viability, PPARα activation and cell membrane micro-viscosity. Instead, N-acetyl-L-cysteine, a scavenger of reactive oxygen species, restored cell motility and gap junctional coupling in fenofibrate-treated DU-145 cell populations. These data indicate that two parameters crucial for cancer cell metastatic potential, i.e. cell motility and gap junctional coupling, are inhibited by fenofibrate. Thus, fenofibrate affects prostate cancer cell invasion via an orchestrated action on versatile cancer cell properties determining this process. A novel mechanism of anti-invasive activity of fenofibrate, which depends on its interference with cell motility and the function of gap junctions regulated by reactive oxygen species, is suggested.

CD44+ cells determine fenofibrate-induced microevolution of drug-resistance in prostate cancer cell populations

Combinations of metabolic blockers (incl. fenofibrate) with chemotherapeutic drugs interfere with the drug-resistance of prostate cancer cells. However, their effect on cancer stem cells-dependent microevolution of prostate cancer malignancy remains unaddressed. Here, we hypothesize that the combined docetaxel/fenofibrate treatment prompts the selective expansion of cancer stem cells that affects the microevolution of their progenies. Accordingly, we adapted a combined in vitro/in vivo approach to identify biological and therapeutic consequences of this process. Minute subpopulations of docetaxel-resistant CD133high and/or CD44high cancer stem cell-like (SCL) cells were found in prostate cancer DU145 and PC3 cell populations. When pretreated with docetaxel, they readily differentiated into docetaxel-resistant CD44negative "bulk" cells, thus accounting for the microevolution of drug-resistant cell lineages. Combined docetaxel/fenofibrate treatment induced the generation of poly(morpho)nuclear giant cells and drug-resistant CD44high SCL cells. However, the CD44negative offspring of docetaxel- and docetaxel/fenofibrate-treated SCLs remained relatively sensitive to the combined treatment, while retaining enhanced resistance to docetaxel. Long-term propagation of drug-resistant SCL-derived lineages in the absence of docetaxel/fenofibrate resulted in their reverse microevolution toward the drug-sensitivity and invasive phenotype. Consequently, prostate tumors were able to recover from the combined docetaxel/fenofibrate stress after the initial arrest of their expansion in vivo. In conclusion, we have confirmed the potential of fenofibrate for the metronomic treatment of drug-resistant prostate tumors. However, docetaxel/fenofibrate-induced selective expansion of hyper-resistant CD44high SCL prostate cells and their "bulk" progenies prompts the microevolution of prostate tumor drug-resistance. This process can limit the implementation of metabolic chemotherapy in prostate cancer treatment.

Epidermal Growth Factor (EGF) Augments the Invasive Potential of Human Glioblastoma Multiforme Cells via the Activation of Collaborative EGFR/ROS-Dependent Signaling

Abnormal secretion of epidermal growth factor (EGF) by non-neuronal cells (e.g., glioma-associated microglia) establishes a feedback loop between glioblastoma multiforme (GBM) invasion and a functional disruption of brain tissue. Considering the postulated significance of this vicious circle for GBM progression, we scrutinized mechanisms of EGF-dependent pro-invasive signaling in terms of its interrelations with energy metabolism and reactive oxygen species (ROS) production. The effects of EGF on the invasiveness of human glioblastoma T98G cells were estimated using time-lapse video microscopy, immunocytochemistry, cell cycle assay, immunoblot analyses, and Transwell^® assay. These techniques were followed by quantification of the effect of EGFR (Epidermal Growth Factor Receptor) and ROS inhibitors on the EGF-induced T98G invasiveness and intracellular ROS, ATP, and lactate levels and mitochondrial metabolism. The EGF remarkably augmented the proliferation and motility of the T98G cells. Responses of these cells were accompanied by cellular rear–front polarization, translocation of vinculin to the leading lamellae, and increased promptness of penetration of micropore barriers. Erlotinib (the EGFR inhibitor) significantly attenuated the EGF-induced T98G invasiveness and metabolic reprogramming of the T98G cells, otherwise illustrated by the increased mitochondrial activity, glycolysis, and ROS production in the EGF-treated cells. In turn, ROS inhibition by N-acetyl-L-cysteine (NAC) had no effect on T98G morphology, but considerably attenuated EGF-induced cell motility. Our data confirmed the EGFR/ROS-dependent pro-neoplastic and pro-invasive activity of EGF in human GBM. These EGF effects may depend on metabolic reprogramming of GBM cells and are executed by alternative ROS-dependent/-independent pathways. The EGF may thus preserve bioenergetic homeostasis of GBM cells in hypoxic regions of brain tissue.