Tubulin immunohistochemistry. Fixation methods affect the response of spinal cord cells in vitro

Evaluation of Anticancer and Anti-Mitotic Properties of Quinazoline and Quinazolino-Benzothiadiazine Derivatives

BACKGROUND

Cancer is one of the major health and social-economic problems despite considerable progress in its early diagnosis and treatment. Owing to the emergence and increase of multidrug resistance to various conventional drugs, and the continuing importance of health-care expenditure, many researchers have focused on developing novel and effective anticancer compounds.

OBJECTIVE

Chemical repositories provide a good platform to evaluate and exploit known chemical entities for the identification of other biological activities. In the present study, we have selected an in-house library of synthesized compounds based on two different pharmacophoric scaffolds to evaluate their cytotoxic potency on various cancer cell lines and mechanisms of action.

METHODS

A series of in-house synthesized quinazoline and quinazolino-benzothiadiazine derivatives were investigated for their anticancer efficacy against a panel of five cancer (DU145, MCF7, HepG2, SKOV3 and MDA-MB-231) and one normal (MRC5) cell lines. Furthermore, the active compound of the study was investigated to elucidate the mechanism of cytotoxicity by performing series of experiments such as cell cycle analysis, inhibition of tubulin polymerization, alteration of mitochondrial membrane potential, determination of endocytic pathway for drug uptake pathway and combination drug treatment.

RESULTS

Among all the tested compounds, fifteen of them exhibited promising growth-inhibitory effect (0.15- 5.0μM) and induced cell cycle arrest in the G2/M phase. In addition, the selected compounds inhibited the microtubule assembly; altered mitochondrial membrane potential and enhanced the levels of caspase-9 in MCF-7 cells. Furthermore, the active compound with a combination of drugs showed a synergistic effect at lower concentrations, and the drug uptake was mediated through clathrin-mediated endocytic pathway.

CONCLUSION

Our results indicated that quinazoline and quinazolino-benzothiadiazine conjugates could serve as potential leads in the development of new anticancer agents.

Introduction

The major advancements in biomedical research over the past 30 years have been based in the broad field of molecular biology. DNA, RNA, and proteins are now routinely sequenced, altered, and their functions analyzed in great detail. The in situ-based methodologies (immunohistochemistry and in situ hybridization) were in their infancy 30 years ago. Today, they are mainstream, as evidenced by the tens of thousands of peer review articles published each year that have used either methodology. Still, much remains to be learned about how to maximize the power of immunohistochemistry and in situ hybridization. This book starts by building a foundation, assuming little or no prior knowledge in the area of molecular biology. I hope that, at the end of the book, you will have a fount of knowledge that allows you to be very knowledgeable and capable in the in situ-based molecular pathology methods.

Distinctive structural and cytoskeletal properties of the long-surviving neurons in cell cultures of embryonic spinal cord

A distinctive population of neurons survives for longer than 3 months in cell cultures of chick or rat spinal cord. These neurons form a minor proportion (1%) of the neurons initially developing in the cultures, but are the only ones to survive longer than 30 days in vitro. In addition to their longevity, they share important morphological and cytoskeletal characteristics, which render them distinctive as a group even in early cultures which contain numerous other neurons of short-term viability. Each long-surviving neuron projects one neurite of great length relative to its other neurites, or to those of the shorter-lived neurons, and the length of this neurite is maintained constant for many weeks in vitro. This well-defined morphological feature may indicate the lineage(s) of these neurons. Structurally these cells are very different to the shorter-lived neurons. They are rich in neurofilaments and contain very few microtubules, whereas the shorter-lived neurons contain few neurofilaments but many microtubules. These differences in cytoskeleton coincide exactly with the distinction between limited and prolonged survival in vitro, and the possibility is considered that cytoskeletal stability in the presence of numerous small inflows of calcium might underlie "hardiness" in vitro. The state of development of the long-lived neurons is considered in the context of their shared features, and it is suggested that they may provide a model in which the regulation of development of neuronal function can be analysed.

Affinity of chick microglia in vitro for ricin 120

The distribution of binding sites for ricin 120 in cell cultures of spinal cord from the chick embryo was examined. A characteristic pattern was observed, which remained similar in cultures fixed by a variety of methods. Light microscopy demonstrated that the most prominent staining was of small rounded or amoeboid cells. Electron microscopy showed that ricin was bound over their entire surfaces. The ultrastructural characteristics of these cells suggest their identification as microglia.