1.A phenotypic screen identifies microtubule plus end assembly regulators that can function in mitotic spindle orientation.
Stolz A1, Ertych N, Bastians H. Cell Cycle. 2015;14(6):827-37. doi: 10.1080/15384101.2014.1000693.
Proper regulation of microtubule dynamics during mitosis is essential for faithful chromosome segregation. In fact, recently we discovered increased microtubule plus end assembly rates that are frequently observed in human cancer cells as an important mechanism leading to whole chromosome missegregation and chromosomal instability (CIN). However, the genetic alterations responsible for increased microtubule polymerization rates in cancer cells remain largely unknown. The identification of such lesions is hampered by the fact that determining dynamic parameters of microtubules usually involves analyses of living cells, which is technically difficult to perform in large-scale screening settings. Therefore, we sought to identify alternative options to systematically identify regulators of microtubule plus end polymerization. Here, we introduce a simple and robust phenotypic screening assay that is based on the analyses of monopolar mitotic spindle structures that are induced upon inhibition of the mitotic kinesin Eg5/KIF11.
2.Novel hybrid DHPM-fatty acids: synthesis and activity against glioma cell growth in vitro.
Treptow TG1, Figueiró F2, Jandrey EH2, Battastini AM2, Salbego CG2, Hoppe JB2, Taborda PS1, Rosa SB1, Piovesan LA1, Montes D'Oca Cda R3, Russowsky D3, Montes D'Oca MG4. Eur J Med Chem. 2015 May 5;95:552-62. doi: 10.1016/j.ejmech.2015.03.062. Epub 2015 Mar 28.
We described the first synthesis of fatty acid 3,4-dihydropyrimidinones (DHPM-fatty acids) using the Biginelli multicomponent reaction. Antiproliferative activity on two glioma cell lines (C6 rat and U-138-MG human) was also reported. The novel DHPM-fatty acids reduced glioma cell viability relative to temozolomide. Hybrid oxo-monastrol-palmitic acid was the most potent, reducing U-138-MG human cell viability by ca. 50% at 10 μM. In addition, the DHPM-fatty acids showed a large safety range to neural cells, represented by the organotypic hippocampal culture. These results suggest that the increased lipophilicity of DHPM-fatty acids offer a promising approach to overcoming resistance to chemotherapy and may play an important role in the development of new antitumor drugs.
3.Erythroblast enucleation is a dynein-dependent process.
Kobayashi I1, Ubukawa K1, Sugawara K2, Asanuma K3, Guo YM1, Yamashita J3, Takahashi N1, Sawada K4, Nunomura W5. Exp Hematol. 2016 Apr;44(4):247-256.e12. doi: 10.1016/j.exphem.2015.12.003. Epub 2015 Dec 24.
Mammalian erythroblasts undergo enucleation through a process thought to be similar to cytokinesis. Microtubule-organizing centers (MTOCs) mediate organization of the mitotic spindle apparatus that separates the chromosomes during mitosis and are known to be crucial for proper cytokinesis. However, the role of MTOCs in erythroblast enucleation remains unknown. We therefore investigated the effect of various MTOC inhibitors on cytokinesis and enucleation using human colony-forming units-erythroid (CFU-Es) and mature erythroblasts generated from purified CD34(+) cells. We found that erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA), a dynein inhibitor, and monastrol, a kinesin Eg5 inhibitor, as well as various inhibitors of MTOC regulators, including ON-01910 (Plk-1), MLN8237 (aurora A), hesperadin (aurora B), and LY294002 (PI3K), all inhibited CFU-E cytokinesis. Among these inhibitors, however, only EHNA blocked enucleation. Moreover, terminally differentiated erythroblasts expressed only dynein; little or none of the other tested proteins was detected.
4.Discovery of novel spiro 1,3,4-thiadiazolines as potent, orally bioavailable and brain penetrant KSP inhibitors.
Mansoor UF1, Angeles AR2, Dai C2, Yang L2, Vitharana D2, Basso AD3, Gray K3, Tang H4, Liu M3, Liang L3, Allbritton O3, Siddiqui MA2. Bioorg Med Chem. 2015 May 15;23(10):2424-34. doi: 10.1016/j.bmc.2015.03.052. Epub 2015 Mar 27.
Kinesin spindle protein (KSP) is a mitotic kinesin that is expressed only in proliferating cells and plays a key role in spindle pole separation, formation of a bipolar mitotic spindle, as well as centrosome separation and maturation. Inhibition of KSP has the potential to provide anti-tumor activity while avoiding peripheral neuropathy associated with some microtubule-targeted drugs. Based on MK-0731 and related heterocyclic compounds targeting the KSP monastrol binding site, structurally constrained spiro-cyclic KSP inhibitors were designed. In particular, rapid evaluation and optimization of the novel spiro 1,3,4-thiadiazolines resulted in a series of potent KSP inhibitors demonstrating mechanism based activities in cells, including induction of the mitotic marker phospho-histone H3 and induction of monaster spindle formation. Further optimization of the pharmacokinetic (PK) properties afforded MK-8267 as a potent, orally bioavailable and brain penetrant KSP inhibitor which showed anti-tumor activity in preclinical xenograft models.