chir-99021 and Carcinoma--Non-Small-Cell-Lung

Glycogen synthase kinase-3 (GSK3) is over-expressed and hyperactivated in non-small cell lung carcinoma (NSCLC) and plays a role in ensuring the correct alignment of chromosomes on the metaphase plate during mitosis through regulation of microtubule stability. This makes the enzyme an attractive target for cancer therapy. We examined the effects of a selective cell-permeant GSK3 inhibitor (CHIR99021), used alone or in combination with paclitaxel, using an in vitro cell growth assay, a quantitative chromosome alignment assay, and a tumor xenograft model. CHIR99021 inhibits the growth of human H1975 and H1299 NSCLC cell lines in a synergistic manner with paclitaxel. CHIR99021 and paclitaxel promoted a synergistic defect in chromosomal alignment when compared to each compound administered as monotherapy. Furthermore, we corroborated our in vitro findings in a mouse tumor xenograft model. Our results demonstrate that a GSK3 inhibitor and paclitaxel act synergistically to inhibit the growth of NSCLC cells in vitro and in vivo via a mechanism that may involve converging modes of action on microtubule spindle stability and thus chromosomal alignment during metaphase. Our findings provide novel support for the use of the GSK3 inhibitor, CHIR99021, alongside taxol-based chemotherapy in the treatment of human lung cancer.

Topics: Animals; Antineoplastic Agents, Phytogenic; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Chromosome Aberrations; Drug Synergism; Drug Therapy, Combination; Glycogen Synthase Kinase 3; Humans; Lung Neoplasms; Male; Mice; Mice, Nude; Paclitaxel; Pyridines; Pyrimidines; RNA Interference; RNA, Small Interfering

The single-agent activity of rapalogs (rapamycin and its analogues) in most tumor types has been modest at best. The underlying mechanisms are largely unclear. In this report, we have uncovered a critical role of GSK3 in regulating degradation of some oncogenic proteins induced by rapalogs and cell sensitivity to rapalogs. The basal level of GSK3 activity was positively correlated with cell sensitivity of lung cancer cell lines to rapalogs. GSK3 inhibition antagonized rapamycin's growth inhibitory effects both in vitro and in vivo, while enforced activation of GSK3β sensitized cells to rapamycin. GSK3 inhibition rescued rapamcyin-induced reduction of several oncogenic proteins such as cyclin D1, Mcl-1 and c-Myc, without interfering with the ability of rapamycin to suppress mTORC1 signaling and cap binding. Interestingly, rapamycin induces proteasomal degradation of these oncogenic proteins, as evidenced by their decreased stabilities induced by rapamcyin and rescue of their reduction by proteasomal inhibition. Moreover, acute or short-time rapamycin treatment dissociated not only raptor, but also rictor from mTOR in several tested cell lines, suggesting inhibition of both mTORC1 and mTORC2. Thus, induction of GSK3-dependent degradation of these oncogenic proteins is likely secondary to mTORC2 inhibition; this effect should be critical for rapamycin to exert its anticancer activity.

Topics: Adaptor Proteins, Signal Transducing; Animals; Antibiotics, Antineoplastic; Carcinoma, Non-Small-Cell Lung; Carrier Proteins; Cell Cycle; Cell Line, Tumor; Drug Interactions; Enzyme Activation; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Indoles; Lung Neoplasms; Maleimides; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Mice; Mice, Nude; Multiprotein Complexes; Neoplasm Proteins; Proteasome Endopeptidase Complex; Protein Stability; Proteolysis; Pyridines; Pyrimidines; Rapamycin-Insensitive Companion of mTOR Protein; Recombinant Fusion Proteins; Regulatory-Associated Protein of mTOR; RNA Interference; RNA, Small Interfering; Sirolimus; TOR Serine-Threonine Kinases; Tumor Stem Cell Assay; Xenograft Model Antitumor Assays

Wnt and Notch signaling pathways both play essential roles and interact closely in development and carcinogenesis, but their interaction in non-small-cell lung cancer (NSCLC) is poorly unknown. Here we investigated the effects of CHIR99021, a Wnt signaling agonist, or Notch3-shRNA, or the combined application of CHIR99021 and Notch3-shRNA on cell proliferation and apoptosis, as well as the expressions of Notch3, its downstream genes, cyclinA and caspase-3. Our results showed that CHIR99021 up-regulated the expression of Notch3 protein and HES1 and HEYL mRNA. CHIR99021 promoted cell proliferation and the expression of cyclinA, which were inhibited by Notch3-shRNA in these three cell lines. Moreover, Notch3-shRNA significantly attenuated the positive effects of CHIR99021 on cell proliferation and cyclinA in H460 and H157. As for apoptosis, Notch3-shRNA induced cell apoptosis and increased the expression of caspase-3, whereas CHIR99021 showed the different effects in these three cell lines. The inhibitory effect of CHIR99021 on apoptosis was significantly weakened by Notch3-shRNA only in H460. Overall, although the effects of CHIR99021 and the combined application of CHIR99021 and Notch3-shRNA on the cell proliferation and apoptosis aren't completely similar in the three cell lines, our findings still indicate that Notch3 signaling can be activated by canonical Wnt signaling and a functional link between Wnt and Notch signaling pathways exists in NSCLC, at least, which partially is associated with their regulations on the expressions of cyclinA and caspase-3.

Topics: Apoptosis; Blotting, Western; Carcinoma, Non-Small-Cell Lung; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cyclin A; DNA Primers; Electrophoresis, Polyacrylamide Gel; Gene Expression Regulation; Humans; Microscopy, Fluorescence; Pyridines; Pyrimidines; Real-Time Polymerase Chain Reaction; Receptor, Notch3; Receptors, Notch; RNA, Small Interfering; Wnt Signaling Pathway