Cytotoxicity of rhein, the active metabolite of sennoside laxatives, is reduced by multidrug resistance-associated protein 1

Anthranoid laxatives, belonging to the anthraquinones as do anthracyclines, possibly increase colorectal cancer risk. Anthracyclines interfere with topoisomerase II, intercalate DNA and are substrates for P-glycoprotein and multidrug resistance-associated protein 1. P-glycoprotein and multidrug resistance-associated protein 1 protect colonic epithelial cells against xenobiotics. The aim of this study was to analyse the interference of anthranoids with these natural defence mechanisms and the direct cytotoxicity of anthranoids in cancer cell lines expressing these mechanisms in varying combinations. A cytotoxicity profile of rhein, aloe emodin and danthron was established in related cell lines exhibiting different levels of topoisomerases, multidrug resistance-associated protein 1 and P-glycoprotein. Interaction of rhein with multidrug resistance-associated protein 1 was studied by carboxy fluorescein efflux and direct cytotoxicity by apoptosis induction. Rhein was less cytotoxic in the multidrug resistance-associated protein 1 overexpressing GLC4/ADR cell line compared to GLC4. Multidrug resistance-associated protein 1 inhibition with MK571 increased rhein cytotoxicity. Carboxy fluorescein efflux was blocked by rhein. No P-glycoprotein dependent rhein efflux was observed, nor was topoisomerase II responsible for reduced toxicity. Rhein induced apoptosis but did not intercalate DNA. Aloe emodin and danthron were no substrates for MDR mechanisms. Rhein is a substrate for multidrug resistance-associated protein 1 and induces apoptosis. It could therefore render the colonic epithelium sensitive to cytotoxic agents, apart from being toxic in itself

P5447Prognostic significance of carboxy-terminal telopeptide (ICTP) and Caspase-3 in patients with non-ischemic dilated cardiomyopathy

Abstract Background Non-ischemic dilated cardiomyopathy (niDCM) is a common debilitating disease leading to heart failure and poor prognosis. Therefore, a reliable diagnosis of niDCM and search of prognostic biomarkers is a task of paramount importance preventing final destruction of myocardium and improving the outcomes of the disease. The aim of the study was to evaluate the prognostic value of carboxy-terminal telopeptide (ICTP), a marker of myocardial collagen I degradation, and Caspase-3, a marker of apoptosis, in serum and endomyocardium biopsies (EMBs) of patients with niDCM. Methods 34 consecutive patients (male 25 (78%); 43.83±12.17 years) with niDCM (average of left ventricle (LV) end-diastolic diameter 6.94±0.78 cm, LV ejection fraction 24.97±6.93%, mean pulmonary capillary wedge pressure 32.9±8.7 mmHg) were enrolled in the study. The levels of ICTP and Caspase-3 in patients' serum and EMBs were measured by ELISA. After a follow-up period of 5 years, 18 patients (53%) have reached the primary composite end-point of heart failure: 6 patients (17.6%) died, 6 patients (17.6%) had heart transplantation and 6 patients (17.6%) underwent left ventricle assist device implantation. Results Univariate Cox proportional hazard model and ROC curve analysis identified levels of ICTP and Caspase-3 in serum as predictors of composite end-point (Table 1). However, the levels of ICTP and Caspase-3 in EMBs had no prognostic value. The cut-off values of serum biomarkers for prediction of the outcome were 13.43 pg/mg protein (sensitivity 67%; specificity 81%) for ICTP and 10.21 pg/mg protein (sensitivity 53%; specificity 87%) for Caspase-3. Univariate Cox regression analysis revealed that patients with higher levels of ICTP and Caspase-3 than cut-off values in serum had higher risk of reaching the composite end-point compared to the patients with lower cut-off values (HR 4.4 (95% CI: 1.6–12.1) and 3.15 (95% CI: 1.2–8.29), respectively). Kaplan-Meier survival analysis demonstrated that patients with serum Caspase-3 and ICTP levels above cut-off values had significantly worse outcome (p=0.01 and p=0.002, respectively). Table 1 Biomarkers (pg/mg protein) Mean ± SD HR (95% CI) p-value AUC (95% CI) ICTP in serum 15.26±10.59 1.052 (1.013–1.093) 0.009 0.71 (0.53–0.89) ICTP in EMB 132±295 0.999 (0.998–1.001) 0.56 0.45 (0.28–0.61) Caspase-3 in serum 7.78±9.86 1.047 (1.002–1.093) 0.04 0.69 (0.51–0.87) Caspase-3 in EMB 283±282 1 (0.998–1.002) 0.92 0.50 (0.28–0.72) Conclusion The findings show that increased serum levels of Caspase-3 and ICTP are significantly associated with poor outcome in patients with niDCM. Acknowledgement/Funding the Research Council of Lithuania (Grants nos. MIP-086/2012 and MIP-011/2014), the European Union, EU-FP7, SARCOSI Project (no. 291834) </jats:sec

Cardiovascular drugs and osteoarthritis:effects of targeting ion channels

Abstract Osteoarthritis (OA) and cardiovascular diseases (CVD) share many similar features, including similar risk factors and molecular mechanisms. A great number of cardiovascular drugs act via different ion channels and change ion balance, thus modulating cell metabolism, osmotic responses, turnover of cartilage extracellular matrix and inflammation. These drugs are consumed by patients with CVD for many years; however, information about their effects on the joint tissues has not been fully clarified. Nevertheless, it is becoming increasingly likely that different cardiovascular drugs may have an impact on articular tissues in OA. Here, we discuss the potential effects of direct and indirect ion channel modulating drugs, including inhibitors of voltage gated calcium and sodium channels, hyperpolarization-activated cyclic nucleotide-gated channels, β-adrenoreceptor inhibitors and angiotensin-aldosterone system affecting drugs. The aim of this review was to summarize the information about activities of cardiovascular drugs on cartilage and subchondral bone and to discuss their possible consequences on the progression of OA, focusing on the modulation of ion channels in chondrocytes and other joint cells, pain control and regulation of inflammation. The implication of cardiovascular drug consumption in aetiopathogenesis of OA should be considered when prescribing ion channel modulators, particularly in long-term therapy protocols

The effect of CaV1.2 inhibitor nifedipine on chondrogenic differentiation of human bone marrow or menstrual blood-derived mesenchymal stem cells and chondrocytes

Abstract Cartilage is an avascular tissue and sensitive to mechanical trauma and/or age-related degenerative processes leading to the development of osteoarthritis (OA). Therefore, it is important to investigate the mesenchymal cell-based chondrogenic regenerating mechanisms and possible their regulation. The aim of this study was to investigate the role of intracellular calcium (iCa²⁺) and its regulation through voltage-operated calcium channels (VOCC) on chondrogenic differentiation of mesenchymal stem/stromal cells derived from human bone marrow (BMMSCs) and menstrual blood (MenSCs) in comparison to OA chondrocytes. The level of iCa²⁺ was highest in chondrocytes, whereas iCa²⁺ store capacity was biggest in MenSCs and they proliferated better as compared to other cells. The level of CaV1.2 channels was also highest in OA chondrocytes than in other cells. CaV1.2 antagonist nifedipine slightly suppressed iCa²⁺, Cav1.2 and the proliferation of all cells and affected iCa²⁺ stores, particularly in BMMSCs. The expression of the CaV1.2 gene during 21 days of chondrogenic differentiation was highest in MenSCs, showing the weakest chondrogenic differentiation, which was stimulated by the nifedipine. The best chondrogenic differentiation potential showed BMMSCs (SOX9 and COL2A1 expression); however, purposeful iCa²⁺ and VOCC regulation by blockers can stimulate a chondrogenic response at least in MenSCs