No abstract

The quasi-reversible, diffusion controlled behavior of rosmarinic acid (RA) on a disposable pencil graphite electrode (PGE) was established by cyclic voltammetry. Using the anodic oxidation peak presented by RA on the PGE a differential pulse voltammetric (DPV) method was developed for the quantitative determination of RA. The linear range was 10 −8 -10 −5 M RA and the detection and quantification limits were 7.93 × 10 −9 M and 2.64 × 10 −8 M RA, respectively. The applicability of the developed method was tested by recovery studies and by the assessment of the total polyphenolic contents (TPC DPV ) of green, white and black Turkish teas, which were found to be 40.74, 30.04 and 23.97 mg rosmarinic acid equivalent/g dry tea, respectively. These results were in good agreement with those obtained by the Folin-Ciocalteu method. The developed method is a sensitive and cheap tool for the rapid and precise evaluation of TPC DPV of tea samples.

Studies with breast cancer cells, showed that microRNAs (miRNAs) act as regulators of signaling pathways playing a key role in tumor progression and being targeted in chemotherapy. Deregulation of these pathways by altered miRNA expression or single nucleotide polymorphisms (SNPs) found in certain miRNA genes have been shown to lead tumor growth, metastasis, angiogenesis, and drug resistance. miRNAs have also been indicated to act on stem cell selfrenewal and alter signal transduction in cancer stem-like cells (CSC), which are resistant to many conventional therapies and account for the inability of these therapies to cure cancers. By considering these findings, miRNAs are proposed as potential novel biomarkers as well as therapeutic targets in new anti-cancer strategies. In this review, the miRNAs found to be involved in breast cancer chemoresistance will be covered together with breast CSC and their contribution to chemotherapy resistance.

Human ether-a-go-go related gene (herg) encoding HERG K(+) channel has been demonstrated in many previous studies with its association to cell cycle progression and growth in tumor cells. The upregulated expression of HERG K+ channels was determined in different tumor types. Furthermore, not only full-length transcript herg1 but also a truncated isoform herg1b was shown to be expressed in cancer cells. In this study, the expression levels of herg1 and herg1b and the impact of K897T mutation on their expressions were investigated in pediatric acute myeloid leukemia (pAML). Expression levels of herg1 and herg1b isoforms were analyzed by quantitative real time polymerase chain reaction (PCR) in pAML patients together with healthy donors, and their expressions were confirmed by western blotting. The 2690 A>C nucleotide variation in KCNH2 gene corresponding to K897T amino acid change was analyzed by PCR followed by restriction enzyme digestion. herg1b overexpression was observed in tumor cells compared to healthy controls (P = .0024). However, herg1 expression was higher in healthy control cells than tumor cells (P = .001). The prevalence of polymorphic allele 897T was 26% in our patient group and 897T carriers showed increased herg1b expression compared to wild-type allele carriers. Our results demonstrate the presence of the increased levels of herg1b expression in pAML. In addition, we report for the first time that, pAML subgroup with HERG 897K/K genotype compared to 897K/T and T/T genotypes express increased levels of herg1b. In conclusion, HERG 897K/K genotype with increased level of herg1b expression might well be a prognostic marker for pAML.