The Roles of Notch3 on the Cell Proliferation and Apoptosis Induced by CHIR99021 in NSCLC Cell Lines: A Functional Link between Wnt and Notch Signaling Pathways
PLOS ONE
Authors: Li, Chunyan; Zhang, Siyang; Lu, Yao; Zhang, Ying; Wang, Enhua; Cui, Zeshi
Abstract
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.
Segmental expression of Notch and Hairy genes in nephrogenesis
AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY
Authors: Chen, LH; Al-Awqati, Q
Abstract
Notch signaling pathway genes are required for nephrogenesis, raising the possibility that Notch effector Hairy-related genes should also control nephron formation. We performed in situ hybridization of Hairy transcription factors with segment-specific lectins and/or antibodies during early nephrogenesis to identify their possible roles in segment identity of the nephron. We found that among all of Notch downstream Hairy genes, only Hes1, Hes5, Hey1, and HeyL were expressed in a segment-specific manner in early nephrons and their expression pattern changed dynamically during metanephric development. Based on these patterns of expression, it was possible to propose a pairwise association of specific ligand and receptor and to suggest that the effector of this association is one of the Hairy transcription factors. We found that Hes5 is specifically expressed in the anlage of the loop of Henle, suggesting that it might be involved in the determination of its cell identity. We also examined the morphological appearance of kidneys from mice where the Hes1 or Hes5 genes were deleted and found that at least at the gross morphological level, there was little difference from wild-type kidneys. Because Hairy genes associate with other transcription factors to exert their effect, it is necessary to examine a more complete array of genetic deletions before a conclusion can be reached regarding their role in kidney development. These studies provide the basis for the future development of strategies to examine the role of individual effector molecules in the determination of the differentiation pattern of the nephron.