Surface plasmon resonance-biosensor detects the diversity of responses against epidermal growth factor in various carcinoma cell lines

Surface plasmon resonance (SPR) biosensor detects intracellular signaling events as a change of the angle of resonance (AR). We previously reported that the activation of epidermal growth factor receptor (EGFR) on keratinocytes causes a unique triphasic change of AR, whereas the activation of other receptors, such as IgE receptor and adenosine A3 receptor on mast cells, causes a transient monophasic increase of AR. To study the mechanism of AR changes induced by EGFR activation, we introduced wild and mutated EGFR cDNAs into Chinese hamster ovary (CHO) cells and analyzed changes of AR in response to EGF. CHO cells expressing wild-type EGFR showed a triphasic change of AR, whereas cells expressing kinase-dead EGFR (K721 M) showed minimum change of AR. A phosphatidylinositol 3-kinase inhibitor, wortmannin, attenuated the third phase of AR change in CHO cells expressing wild-type EGFR. The pattern of AR change was independent on the concentration of EGF. We also analyzed changes of AR with a nontumorigenic keratinocyte cell line, HaCaT, and several cell lines of carcinoma to explore the feasibility of SPR biosensor as a tool for clinical diagnosis. The activation of HaCaT cells and one out of six carcinoma cell lines showed a full triphasic change of AR. In contrast, five out of the six cell lines showed mono- or bi-phasic change of AR. These results suggest that EGF induces the SPR signals via the phosphorylation of EGFR, and provide a possibility that the SPR biosensor could be applied to the real-time detection and diagnosis of malignant tumors

An Autopsy Case of Carcinosarcoma of the Esophagus

A case of carcinosarcoma, a rare polypoid tumor of the esophagus is presented. The characteristic gross and microscopic features as well as a discussion of the histogenesis of the sarcomatous elements are presented by microscopic, immunohistochemical and electron micronscopic examinations. Immunohistochemically, keratin and EMA (epithelial membrane antigen) were demonstrated in the islands of squamous cell carcinoma within the sarcomatous elements and in the carcinoma in situ at the border of normal mucosa. Vimentin, desmin, actin, myoglobin, factor VIII, S-100 protein, NSE, neuraminidase were not demonstrated in both the carcinomatous and the sarcomatous elements except for a positive reactivity to a-1-antichymotrypsin in the sarcomatous elements at part. It is suggested that the sarcomatous elements are of epithelial origin based on the facts as follows : 1 transition from overlying epithelium or carcinomatous islands to sarcomatous elements existent ; 2 some small tubules were formed within the sarcomatous elements, which showed transition into the sarcomatous elements ; and 3 a part of the sarcomatous elements revealed either positive or weak reactivity to keratin and EMA. Further, weak reactivity to keratin and EMA in the more anaplastic lesion may reflect the lack of tonofilaments and desmosomes in the ultrastructural findings

Importin-β and the small guanosine triphosphatase Ran mediate chromosome loading of the human chromokinesin Kid

Nucleocytoplasmic transport factors mediate various cellular processes, including nuclear transport, spindle assembly, and nuclear envelope/pore formation. In this paper, we identify the chromokinesin human kinesin-like DNA binding protein (hKid) as an import cargo of the importin-α/β transport pathway and determine its nuclear localization signals (NLSs). Upon the loss of its functional NLSs, hKid exhibited reduced interactions with the mitotic chromosomes of living cells. In digitonin-permeabilized mitotic cells, hKid was bound only to the spindle and not to the chromosomes themselves. Surprisingly, hKid bound to importin-α/β was efficiently targeted to mitotic chromosomes. The addition of Ran–guanosine diphosphate and an energy source, which generates Ran–guanosine triphosphate (GTP) locally at mitotic chromosomes, enhanced the importin-β–mediated chromosome loading of hKid. Our results indicate that the association of importin-β and -α with hKid triggers the initial targeting of hKid to mitotic chromosomes and that local Ran-GTP–mediated cargo release promotes the accumulation of hKid on chromosomes. Thus, this study demonstrates a novel nucleocytoplasmic transport factor–mediated mechanism for targeting proteins to mitotic chromosomes