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Pirinixic acid derivatives, a new class of drug candidates for a range of diseases, interfere with targets including PPARα, PPARγ, 5-lipoxygenase (5-LO), and microsomal prostaglandin and E2 synthase-1 (mPGES1). Since 5-LO, mPGES1, PPARα, and PPARγ represent potential anti-cancer drug targets, we here investigated the effects of 39 pirinixic acid derivatives on prostate cancer (PC-3) and neuroblastoma (UKF-NB-3) cell viability and, subsequently, the effects of selected compounds on drug-resistant neuroblastoma cells. Few compounds affected cancer cell viability in low micromolar concentrations but there was no correlation between the anti-cancer effects and the effects on 5-LO, mPGES1, PPARα, or PPARγ. Most strikingly, pirinixic acid derivatives interfered with drug transport by the ATP-binding cassette (ABC) transporter ABCB1 in a drug-specific fashion. LP117, the compound that exerted the strongest effect on ABCB1, interfered in the investigated concentrations of up to 2μM with the ABCB1-mediated transport of vincristine, vinorelbine, actinomycin D, paclitaxel, and calcein-AM but not of doxorubicin, rhodamine 123, or JC-1. In silico docking studies identified differences in the interaction profiles of the investigated ABCB1 substrates with the known ABCB1 binding sites that may explain the substrate-specific effects of LP117. Thus, pirinixic acid derivatives may offer potential as drug-specific modulators of ABCB1-mediated drug transport.
Background: Recently, we have shown that the ATP-binding cassette (ABC) transporter ABCB1 interferes with the anti-cancer activity of the pan-aurora kinase inhibitor tozasertib (VX680, MK-0457) but not of the aurora kinase A and B inhibitor alisertib (MLN8237). Preliminary data had suggested tozasertib also to be a substrate of the ABC transporter ABCG2, another ABC transporter potentially involved in cancer cell drug resistance. Here, we studied the effect of ABCG2 on the activity of tozasertib and alisertib.
Results: The tozasertib concentration that reduces cell viability by 50 % (IC50) was dramatically increased in ABCG2-transduced UKF-NB-3ABCG2 cells (48.8-fold) compared to UKF-NB-3 cells and vector-transduced control cells. The ABCG2 inhibitor WK-X-34 reduced tozasertib IC50 to the level of non-ABCG2-expressing UKF-NB-3 cells. Furthermore, ABCG2 depletion from UKF-NB-3ABCG2 cells using another lentiviral vector expressing an shRNA against the bicistronic mRNA of ABCG2 and eGFP largely re-sensitised these cells to tozasertib. In contrast, alisertib activity was not affected by ABCG2 expression.
Conclusions: Tozasertib but not alisertib activity is affected by ABCG2 expression. This should be considered within the design and analysis of experiments and clinical trials investigating these compounds.
Background: Various kinase inhibitors are known to be ATP-binding cassette (ABC) transporter substrates and resistance acquisition to kinase inhibitors has been associated to increased ABC transporter expression. Here, we investigated the role of the ABC transporters ABCB1, ABCC1, and ABCG2 during melanoma cell resistance acquisition to the V600-mutant BRAF inhibitors PLX4032 (vemurafenib) and PLX4720. PLX4032 had previously been shown to interfere with ABCB1 and ABCG2. PLX4720 had been demonstrated to interact with ABCB1 but to a lower extent than PLX4032.
Findings: PLX4032 and PLX4720 affected ABCC1- and ABCG2-mediated drug transport in a similar fashion. In a panel of 16 V600E BRAF-mutated melanoma cell lines consisting of four parental cell lines and their sub-lines with acquired resistance to PLX4032, PLX4720, vincristine (cytotoxic ABCB1 and ABCC1 substrate), or mitoxantrone (cytotoxic ABCG2 substrate), we detected enhanced ABC transporter expression in 4/4 cytotoxic ABC transporter substrate-resistant, 3/4 PLX4720-resistant, and 1/4 PLX4032-resistant melanoma cell lines.
Conclusion: PLX4032 has the potential to induce ABC transporter expression but this potential is lower than that of PLX4720 or cytotoxic ABC transporter substrates. Since ABC transporters confer multi-drug resistance, this is of relevance for the design of next-line therapies.
Background: The elderly population deals with multimorbidity (three chronic conditions) and increasinged drug use with age. A comprehensive characterisation of the medication – including prescription and over-the-counter (OTC) drugs – of elderly patients in primary care is still insufficient.
Objectives: This study aims to characterise the medication (prescription and OTC) of multimorbid elderly patients in primary care and living at home by identifying drug patterns to evaluate the relationship between drugs and drug groups and reveal associations with recently published multimorbidity clusters of the same cohort.
Methods: MultiCare was a multicentre, prospective, observational cohort study of 3189 multimorbid patients aged 65 to 85 years in primary care in Germany. Patients and general practitioners were interviewed between 2008 and 2009. Drug patterns were identified using exploratory factor analysis. The relations between the drug patterns with the three multimorbidity clusters were analysed with Spearman-Rank-Correlation.
Results: Patients (59.3% female) used in mean 7.7 drugs; in total 24,535 drugs (23.7% OTC) were detected. Five drug patterns for men (drugs for obstructive pulmonary diseases (D-OPD), drugs for coronary heart diseases and hypertension (D-CHD), drugs for osteoporosis (D-Osteo), drugs for heart failure and drugs for pain) and four drug patterns for women (D-Osteo, D-CHD, D-OPD and drugs for diuretics and gout) were detected. Significant associations between multimorbidity clusters and drug patterns were detectable (D-CHD and CMD: male: ρ = 0.376, CI 0.322–0.430; female: ρ = 0.301, CI 0.624–0.340).
Conclusion: The drug patterns demonstrate non-random relations in drug use in multimorbid elderly patients and systematic associations between drug patterns and multimorbidity clusters were found in primary care.
The human immunodeficiency virus (HIV) protease inhibitor saquinavir shows anticancer activity. Although its nitric oxide-modified derivative saquinavir-NO (saq-NO) was less toxic to normal cells, it exerted stronger inhibition of B16 melanoma growth in syngeneic C57BL/6 mice than saquinavir did. Saq-NO has been shown to block proliferation, upregulate p53 expression, and promote differentiation of C6 glioma and B16 cells. The anticancer activity of substances is frequently hampered by cancer cell chemoresistance mechanisms. Therefore, we here investigated the roles of p53 and the ATP-binding cassette (ABC) transporters P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), and breast cancer resistance protein 1 (BCRP1) in cancer cell sensitivity to saq-NO to get more information about the potential of saq-NO as anticancer drug. Saq-NO exerted anticancer effects in lower concentrations than saquinavir in a panel of human cancer cell lines. Neither p53 mutation or depletion nor expression of P-gp, MRP1, or BCRP1 affected anticancer activity of saq-NO or saquinavir. Moreover, saq-NO sensitized P-gp-, MRP1-, or BCRP1-expressing cancer cells to chemotherapy. Saq-NO induced enhanced sensitization of P-gp- or MRP1-expressing cancer cells to chemotherapy compared with saquinavir, whereas both substances similarly sensitized BCRP1-expressing cells. Washout kinetics and ABC transporter ATPase activities demonstrated that saq-NO is a substrate of P-gp as well as of MRP1. These data support the further investigation of saq-NO as an anticancer drug, especially in multidrug-resistant tumors.
Background: In primary care, patients with multiple chronic conditions are the rule rather than the exception. The Chronic Care Model (CCM) is an evidence-based framework for improving chronic illness care, but little is known about the extent to which it has been implemented in routine primary care. The aim of this study was to describe how multimorbid older patients assess the routine chronic care they receive in primary care practices in Germany, and to explore the extent to which factors at both the practice and patient level determine their views.
Methods: This cross-sectional study used baseline data from an observational cohort study involving 158 general practitioners (GP) and 3189 multimorbid patients. Standardized questionnaires were employed to collect data, and the Patient Assessment of Chronic Illness Care (PACIC) questionnaire used to assess the quality of care received. Multilevel hierarchical modeling was used to identify any existing association between the dependent variable, PACIC, and independent variables at the patient level (socio-economic factors, weighted count of chronic conditions, instrumental activities of daily living, health-related quality of life, graded chronic pain, no. of contacts with GP, existence of a disease management program (DMP) disease, self-efficacy, and social support) and the practice level (age and sex of GP, years in current practice, size and type of practice).
Results: The overall mean PACIC score was 2.4 (SD 0.8), with the mean subscale scores ranging from 2.0 (SD 1.0, subscale goal setting/tailoring) to 3.5 (SD 0.7, delivery system design). At the patient level, higher PACIC scores were associated with a DMP disease, more frequent GP contacts, higher social support, and higher autonomy of past occupation. At the practice level, solo practices were associated with higher PACIC values than other types of practice.
Conclusions: This study shows that from the perspective of multimorbid patients receiving care in German primary care practices, the implementation of structured care and counseling could be improved, particularly by helping patients set specific goals, coordinating care, and arranging follow-up contacts. Studies evaluating chronic care should take into consideration that a patient’s assessment is associated not only with practice-level factors, but also with individual, patient-level factors.