Resistance to DNA Damaging agents produced invasive phenotype of rat glioma cells-characterization of a new in vivo model

Chemoresistance and invasion properties are severe limitations to efficient glioma therapy. Therefore, development of glioma in vivo models that more accurately resemble the situation observed in patients emerges. Previously, we established RC6 rat glioma cell line resistant to DNA damaging agents including antiglioma approved therapies such as 3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and temozolomide (TMZ). Herein, we evaluated the invasiveness of RC6 cells in vitro and in a new orthotopic animal model. For comparison, we used C6 cells from which RC6 cells originated. Differences in cell growth properties were assessed by real-time cell analyzer. Cells’ invasive potential in vitro was studied in fluorescently labeled gelatin and by formation of multicellular spheroids in hydrogel. For animal studies, fluorescently labeled cells were inoculated into adult male Wistar rat brains. Consecutive coronal and sagittal brain sections were analyzed 10 and 25 days post-inoculation, while rats’ behavior was recorded during three days in the open field test starting from 25th day post-inoculation. We demonstrated that development of chemoresistance induced invasive phenotype of RC6 cells with significant behavioral impediments implying usefulness of orthotopic RC6 glioma allograft in preclinical studies for the examination of new approaches to counteract both chemoresistance and invasion of glioma cells

Tubulin isoform composition tunes microtubule dynamics

Microtubules polymerize and depolymerize stochastically, a behavior essential for cell division, motility and differentiation. While many studies advanced our understanding of how microtubule-associated proteins tune microtubule dynamics in trans, we have yet to understand how tubulin genetic diversity regulates microtubule functions. The majority of in vitro dynamics studies are performed with tubulin purified from brain tissue. This preparation is not representative of tubulin found in many cell types. Here we report the 4.2Å cryo-EM structure and in vitro dynamics parameters of α1B/βI+βIVb microtubules assembled from tubulin purified from a human embryonic kidney cell line with isoform composition characteristic of fibroblasts and many immortalized cell lines. We find that these microtubules grow faster and transition to depolymerization less frequently compared to brain microtubules. Cryo-EM reveals that the dynamic ends of α1B/βI+βIVb microtubules are less tapered and that these tubulin heterodimers display lower curvatures. Interestingly, analysis of EB1 distributions at dynamic ends suggests no differences in GTP cap sizes. Lastly, we show that the addition of recombinant α1A/βIII tubulin, a neuronal isotype overexpressed in many tumors, proportionally tunes the dynamics of α1B/βI+βIVb microtubules. Our study is an important step towards understanding how tubulin isoform composition tunes microtubule dynamics

Chapter 9 Moral Responsibility and the Justification of Policies to Preserve Antimicrobial Effectiveness

Restrictive policies that limit antimicrobial consumption, including therapeutically justified use, might be necessary to tackle the problem of antimicrobial resistance. We argue that such policies would be ethically justified when forgoing antimicrobials constitutes a form of easy rescue for an individual. These are cases of mild and self-limiting infections in otherwise healthy patients whose overall health is not significantly compromised by the infection. In such cases, restrictive policies would be ethically justified because they would coerce individuals into fulfilling a moral obligation they independently have. However, to ensure that such justification is the strongest possible, states also have the responsibility to ensure that forgoing antimicrobials is as easy as possible for patients by implementing adequate compensation measures

Potential of Melittin to induce apoptosis and overcome multidrug resistance in human colon cancer cell line

In this study, the anticancer effect of Melittin was demonstrated through its antiproliferative and proapoptotic effects on HT-29 cells, as well as its ability to reverse multidrug resistance. Melittin directly affects the death receptor-dependent apoptotic pathway via increase of the Fas receptor protein expression, Caspase 8 gene expression and activity of Caspase 8. Results of decreased Caspase 9 gene and protein expression, and multi-fold increased expression of Bcl-2 gene suggest that mitochondria and the inner apoptotic pathway are not involved in the execution of Melittin induced apoptosis, as well as redox regulation of apoptosis based on decreased concentration of superoxide anion radicals and no effect glutathione levels. Specially significance of this work are results on ability of Melittin to modulate the metabolism and export system in cancer cells. Based on the increased expression of all the investigated genes related to the biotransformation process, it can be assumed that CYP1A1, CYP1B1, GSTP1 and MRP2 are involved in metabolism of Melittin in HT-29 cells. P-glycoprotein is associated with the occurrence of resistance in anticancer therapy, so its reduced gene and protein expression by Melittin represents significant result in terms of possible therapeutic application and examination.</p