作者: Ruiz-Saenz, Ana ; Kawaguchi, Shinsaku ; Dolan, Brian P ; Kazemi, Soheila ; Oishi, Shinya ; Badr, Christian E ; Paavilainen, Ville O ; Serrill, Jeffrey D ; Ishmael, Jane E ; Moasser, Mark M ; Mattos, Daphne R ; McPhail, Kerry L

Coibamide A is a potent cancer cell toxin and one of a select group of natural products that inhibit protein entry into the secretory pathway via a direct inhibition of the Sec61 protein translocon. Many Sec61 client proteins are clinically relevant drug targets once trafficked to their final destination in or outside the cell, however the use of Sec61 inhibitors to block early biosynthesis of specific proteins is at a pre-clinical stage. In the present study we evaluated the action of coibamide A against human epidermal growth factor receptor (HER, ErbB) proteins in representative breast and lung cancer cell types. HERs were selected for this study as they represent a family of Sec61 clients that is frequently dysregulated in human cancers, including coibamide-sensitive cell types. Although coibamide A inhibits biogenesis of a broad range of Sec61 substrate proteins in a presumed substrate-nonselective manner, endogenous HER3 (ErbB-3) and EGFR (ErbB-1) proteins were more sensitive to coibamide A, and the related Sec61 inhibitor apratoxin A, than HER2 (ErbB-2). Despite this rank order of sensitivity (HER3 > EGFR > HER2), Sec61-dependent inhibition by coibamide A was sufficient to decrease cell surface expression of HER2. We report that coibamide A- or apratoxin A-mediated block of HER3 entry into the secretory pathway is unlikely to be mediated by the HER3 signal peptide alone. HER3 (G11L/S15L), that is fully resistant to the highly substrate-selective cotransin analogue CT8, was more resistant than wild-type HER3 but only at low coibamide A (3 nM) concentrations; HER3 (G11L/S15L) expression was inhibited by higher concentrations of either natural product. Time- and concentration-dependent decreases in HER protein expression induced a commensurate reduction in AKT/MAPK signaling in breast and lung cancer cell types and loss in cell viability. Coibamide A potentiated the cytotoxic efficacy of small molecule kinase inhibitors lapatinib and erlotinib in breast and lung cancer cell types, respectively. These data indicate that natural product modulators of Sec61 function have value as chemical probes to interrogate HER/ErbB signaling in treatment-resistant human cancers.

2019-01-01·Journal of oleo science4区 · 农林科学

Potent <i>in vitro</i> Anti-mouth Cancer (KB) and Immunostimulating Activities of the Job’s Tears (<i>Coix lachryma-jobi</i> Linn.) Seed Semi-purified Extract Cocktails Containing Linoleic Acid

4区 · 农林科学

Article

作者: Chankhampan, Charinya ; Manosroi, Jiradej ; Kitdamrongtham, Worapong ; Manosroi, Aranya ; Manosroi, Worapaka

The crude methanolic and hexane extracts of non-cooked, steamed and roasted from three Job's Tears cultivars were prepared and further semi-purified by liquid-liquid extraction techniques and silica gel column. The six single semi-purified extracts (F1-F6) were combined as nine cocktails (CT1, CT6, CT8, CT13, CT14, CT21, CT24, CT25 and CT31) according to the IC₅₀ values from the preliminary study and investigated for anti-proliferative and apoptotic induction on mouth cancer cell line (KB) and immunostimulating as well as antioxidative activities. The highest anti-proliferative activity was observed in CT13 showing the IC₅₀ value of 0.53±0.45 µg/mL which was higher than 5-fluorouracil and doxorubicin of 20.34 and 1.60 times, respectively. CT1 which was the combination of F1-F6 and CT13 which was the combination of F4-F6 exhibited significant strong synergistic activity with the combination index value (CI) of 0.28. CT1 at 200 µg/mL showed the highest percentages of apoptotic cells (40.65±10.97%) with no necrotic cells, but lower than cisplatin (100 µg/mL) of 2.18 times. CT14 gave the highest immunostimulating activity with the phagocytosis percentage of 13.0±1.7%, but lower than lipopolysaccharide of 1.08 times. CT31 gave the highest free radical scavenging and metal chelating activities with the SC₅₀ and MC₅₀ values of 0.73±0.07 and 1.99±0.24 µg/mL, but lower than ascorbic acid and EDTA of 18.25 and 4.33 times, respectively. The linoleic acid contents related to anti-cancer activity were also examined by HPLC. This study has demonstrated that CT1 composing of F1-F6 at the percentage ratio of 0.71:2.06:81.38: 8.47:4.92:2.46 was the potential cocktails of the semi-purified extracts from the Job's Tears which can be further developed as a novel active compound for oral cancer treatment.

2015-10-08·Oncogene1区 · 医学

Targeting HER3 by interfering with its Sec61-mediated cotranslational insertion into the endoplasmic reticulum

1区 · 医学

Article

作者: Sandhu, M ; Moasser, M M ; Carrasco, Y ; Ruiz-Saenz, A ; Taunton, J ; Maglathlin, R L

There is increasing evidence implicating human epidermal growth factor receptor 3 (HER3) in several types of cancer. However, the development of targeted therapies to inactivate HER3 function has been a challenging endeavor. Its kinase domain functions in allostery not catalysis, and the classical ATP-analog class of tyrosine kinase inhibitors fail to inactivate it. Here we describe a novel approach that eliminates HER3 expression. The small-molecule cotransin CT8 binds the Sec61 translocon and prevents the signal peptide of the nascent HER3 protein from initiating its cotranslational translocation, resulting in the degradation of HER3 but not the other HER proteins. CT8 treatment suppresses the induction of HER3 that accompanies lapatinib treatment of HER2-amplified cancers and synergistically enhances the apoptotic effects of lapatinib. The target selectivities of cotransins are highly dependent on their structure and the signal sequence of targeted proteins and can be narrowed through structure-function studies. Targeting Sec61-dependent processing identifies a novel strategy to eliminate HER3 function.

100 项与 CT-8 (Channel) 相关的药物交易

登录后查看更多信息