Dose- and time-dependent responses of wild-type EGFR and tyrosine kinase domain-mutated EGFR cells to cetuximab and gefitinib treatment

<p><b>Copyright information:</b></p><p>Taken from "Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α"</p><p>http://www.molecular-cancer.com/content/6/1/63</p><p>Molecular Cancer 2007;6():63-63.</p><p>Published online 11 Oct 2007</p><p>PMCID:PMC2117021.</p><p></p> () Absolute cell numbers in each treatment group (control [DMSO]), 5 nM cetuximab, and 0.5 μM gefitinib, all in 0.5% FBS medium) were plotted against the duration of treatment. () The inhibition of cell proliferation after treatment with cetuximab was measured by an MTT assay and is shown as a percentage of the optical density value of control cells (untreated) for each concentration tested. () The inhibition of cell proliferation after treatment with gefitinib was measured as in () and is shown as a percentage of the optical density value of vehicle-treated cells (DMSO) for each concentration tested. Results are shown as the mean of five independent measurements, plus or minus the standard deviation (SD). The magnitude of some SDs was smaller than the symbol size; thus some bars do not appear in the figure

Effects of cetuximab and gefitinib treatment on the levels of total and phosphorylated EGFR and EGFR substrates in cell lines with wild-type and mutated EGFR

<p><b>Copyright information:</b></p><p>Taken from "Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α"</p><p>http://www.molecular-cancer.com/content/6/1/63</p><p>Molecular Cancer 2007;6():63-63.</p><p>Published online 11 Oct 2007</p><p>PMCID:PMC2117021.</p><p></p> Cells from the indicated lines were simultaneously switched to a culture medium containing 0.5% FBS and were either left untreated or treated with cetuximab (2 and 10 nM), vehicle, or gefitinib (0.1 and 0.5 μM) overnight (16 hours). A master medium containing either cetuximab or gefitinib was used in all cell lines. After treatment, the cells were lysed, and equal amounts of cell lysates were subjected to Western blot analysis using antibodies directed against total and phosphorylated EGFR (Y-1068) () and antibodies directed against phosphorylated ERK, Akt, and STAT3 as indicated (). The levels of β-actin and total ERK served as internal controls for equal protein loading in each lane in () and (), respectively. The numeric values under each gel were derived from a densitometric analysis of the signals

Induction of apoptosis in cancer cells with wild-type EGFR or tyrosine kinase domain-mutated EGFR by cetuximab and gefitinib

<p><b>Copyright information:</b></p><p>Taken from "Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α"</p><p>http://www.molecular-cancer.com/content/6/1/63</p><p>Molecular Cancer 2007;6():63-63.</p><p>Published online 11 Oct 2007</p><p>PMCID:PMC2117021.</p><p></p> Cells from each line were left untreated or were treated with vehicle (DMSO), 5 nM cetuximab, or 0.5 μM gefitinib in a medium containing 0.5% FBS. After 16 hours of treatment, the cells were harvested and lysed for quantitative apoptosis measurement by () an enzyme-linked immunosorbent assay, as described in the Methods section, and () Western blot analysis with anti-PARP antibodies. *P < 0.05, **P < 0.01 compared with corresponding controls

Cancer cell lines with wild-type or tyrosine kinase domain-mutated EGFR

<p><b>Copyright information:</b></p><p>Taken from "Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α"</p><p>http://www.molecular-cancer.com/content/6/1/63</p><p>Molecular Cancer 2007;6():63-63.</p><p>Published online 11 Oct 2007</p><p>PMCID:PMC2117021.</p><p></p> () PCR fragments from the indicated cell lines were compared with the wild-type sequence of EGFR. The black arrows indicate the codons E746 to A750, which are present in the EGFR in DiFi cells but have been deleted in HCC827 and HCC2279 cells. Codon L858R substitution in H1975 and H3255 cells is indicated by arrows. () Lysates from the indicated cell lines maintained in regular culture medium were prepared for Western blot analysis using antibodies directed against EGFR, HER2, and HER3, and antibodies directed against total and activation-specific phosphorylated downstream signaling molecules (ERK, Akt, and STAT3). The level of β-actin was used as a reference of lysate protein loading control of each cell line

Expression of HIF-1α/ΔODD mutant leads to cellular resistance to cetuximab without affecting cellular sensitivity to cetuximab-induced inhibition of EGFR signaling

<p><b>Copyright information:</b></p><p>Taken from "Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α"</p><p>http://www.molecular-cancer.com/content/6/1/63</p><p>Molecular Cancer 2007;6():63-63.</p><p>Published online 11 Oct 2007</p><p>PMCID:PMC2117021.</p><p></p> () A431neo and A431/HIF-1α/ΔODD cells were treated as indicated for 16 hours (overnight). Cell lysates were prepared and subjected to Western blot analysis with the indicated antibodies. () Cells were left untreated or treated with the indicated concentrations of cetuximab in culture with 0.5% FBS for 5 days. Relative cell numbers were measured by the MTT assay and are presented as a percentage of the untreated control. () A431neo and A431/HIF-1α/ΔODD cells (300 cells/dish) were cultured, with or without cetuximab (2 nM), for 9 days. After treatment, cells were fixed and the colonies were counted, as described in the Methods section

Downregulation of HIF-1α protein levels in cell lines with wild-type or mutated EGFR after treatment with cetuximab or gefitinib

<p><b>Copyright information:</b></p><p>Taken from "Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α"</p><p>http://www.molecular-cancer.com/content/6/1/63</p><p>Molecular Cancer 2007;6():63-63.</p><p>Published online 11 Oct 2007</p><p>PMCID:PMC2117021.</p><p></p> Cells from the indicated cell lines were treated with cetuximab or gefitinib overnight as described in Figure 4. After treatment, the cells were lysed, and equal amounts of cell lysates were subjected to Western blot analysis using antibodies directed against HIF-1α, as indicated. The level of β-actin served as the internal control for equal protein loading in each lane. The numeric values shown under each gel were derived from a densitometric analysis of the signals

Ectopic expression of a tobacco vacuolar invertase inhibitor in guard cells confers drought tolerance in <i>Arabidopsis</i>

<p>There are several hypotheses that explain stomatal behavior. These include the concept of osmoregulation mediated by potassium and its counterions malate and chlorine and the more recent starch–sugar hypothesis. We have previously reported that the activity of the sucrose cleavage enzyme, vacuolar invertase (VIN), is significantly higher in guard cells than in other leaf epidermal cells and its activity is correlated with stomatal aperture. Here, we examined whether VIN indeed controls stomatal movement under normal and drought conditions by transforming <i>Arabidopsis</i> with a tobacco vacuolar invertase inhibitor homolog (<i>Nt-inhh</i>) under the control of an abscisic acid-sensitive and guard cell-specific promoter (<i>AtRab18</i>). The data obtained showed that guard cells of transgenic <i>Arabidopsis</i> plants had lower VIN activity, stomatal aperture and conductance than that of wild-type plants. Moreover, the transgenic plants also displayed higher drought tolerance than wild-type plants. The data indicate that VIN is a promising target for manipulating stomatal function to increase drought tolerance.</p

Coumarin-Based Thermally Activated Delayed Fluorescence Emitters with High External Quantum Efficiency and Low Efficiency Roll-off in the Devices

Thermally activated delayed fluorescence (TADF) emitters have attracted much interest for their great applications in organic light-emitting diodes (OLEDs), but the TADF OLEDs are limited by large efficiency roll-offs. In this study, we report two coumarin-based TADF emitters, 3-methyl-6-(10<i>H</i>-phenoxazin-10-yl)-1<i>H</i>-isochromen-1-one (PHzMCO) and 9-(10<i>H</i>-phenoxazin-10-yl)-6<i>H</i>-benzo­[<i>c</i>]­chromen-6-one (PHzBCO), with relatively high photoluminescence quantum yields (PLQYs) and extremely small singlet–triplet splittings. OLEDs using these two TADF compounds as the emitters respectively demonstrate high external quantum efficiencies of 17.8% for PHzMCO and 19.6% for PHzBCO, which are the highest among the reported coumarin-derivative-based OLEDs. More importantly, these devices based on PHzMCO and PHzBCO remained 10.3% and 12.9% at 10000 cd m^–2, respectively, showing relatively low efficiency roll-offs at high brightness. These results reveal that the TADF emitters with high PLQYs can effectively reduce the efficiency roll-off in the devices