Zhao L et al. ( 2014)
International journal of clinical and experimental medicine 7 2 337--347
mTOR inhibitor AZD8055 inhibits proliferation and induces apoptosis in laryngeal carcinoma.
The mammalian target of rapamycin (mTOR) kinase forms two multiprotein complexes, mTORC1 and mTORC2, which regulate cell growth, survival, and autophagy. Allosteric inhibitors of mTORC1, such as rapamycin, have been extensively used to study tumor cell growth, proliferation, and autophagy but have shown only limited clinical utility. Here, we describe AZD8055, a novel ATP-competitive inhibitor of mTOR kinase activity, against all class I phosphatidylinositol3-kinase (PI3K) and other members of the PI3K-like kinase family. The study was to determine the effect of AZD8055 on proliferation and apoptosis on Hep-2, a human laryngeal cancer cell line and to investigate the underlying mechanism(s) of action. Hep-2 cells were treated with AZD8055 for 24, 48 or 72 h. MTT was used to determine cell proliferation. Rhodamine 123 and TUNEL staining were used to determine mitochondrial membrane potential and cell apoptosis analyzed by fluorescence-activated cell sorting (FACS). Protein expressions were examined by western blotting. Treatment with AZD8055 inhibited proliferation and induced apoptosis in Hep-2 cells in a dose- and time-dependent manner. During the prolonged treatment with AZD8055, AZD8055 inhibits the mammalian target of rapamycin mTOR. Further experiments showed which signaling cascade p-4EBP1 and substrate EIF4E as well as downstream proteins were down regulated. Furthermore, our study showed that the expression profiles of various BH3-only proteins including Bid, Bad, and Bim, apoptosis regulatory protein cleaved caspase3 was up regulated in a time-dependent manner in Hep-2 cells treated with AZD8055. Thus, in vitro, AZD8055 potently inhibits proliferation and induces apoptosis in head and neck squamous cell carcinoma.
Malchenko S et al. (JAN 2014)
Gene 534 2 400--7
Onset of rosette formation during spontaneous neural differentiation of hESC and hiPSC colonies
In vitro neural differentiation of human embryonic stem cells (hESCs) is an advantageous system for studying early neural development. The process of early neural differentiation in hESCs begins by initiation of primitive neuroectoderm, which is manifested by rosette formation, with consecutive differentiation into neural progenitors and early glial-like cells. In this study, we examined the involvement of early neural markers - OTX2, PAX6, Sox1, Nestin, NR2F1, NR2F2, and IRX2 - in the onset of rosette formation, during spontaneous neural differentiation of hESC and human induced pluripotent stem cell (hiPSC) colonies. This is in contrast to the conventional way of studying rosette formation, which involves induction of neuronal differentiation and the utilization of embryoid bodies. Here we show that OTX2 is highly expressed at the onset of rosette formation, when rosettes comprise no more than 3-5 cells, and that its expression precedes that of established markers of early neuronal differentiation. Importantly, the rise of OTX2 expression in these cells coincides with the down-regulation of the pluripotency marker OCT4. Lastly, we show that cells derived from rosettes that emerge during spontaneous differentiation of hESCs or hiPSCs are capable of differentiating into dopaminergic neurons in vitro, and into mature-appearing pyramidal and serotonergic neurons weeks after being injected into the motor cortex of NOD-SCID mice. ?? 2013 Elsevier B.V.