hes1-protein--human and Carcinoid-Tumor

Hes1 is a key transcriptional regulator primarily controlled by the Notch signaling pathway, and recent studies have demonstrated both an oncogenic and tumor suppressor role for Hes1, depending on the cell type. Small molecules that activate and inhibit Hes1 activity hold promise as future anticancer chemotherapeutics. We have utilized a cell-based dual luciferase assay to identify modulators of Hes1 expression in a medium-throughput format. A modest screen was performed in HCT-116 colon cancer cell lines, and two small molecules were identified and characterized as Hes1 regulators. Compound 3 induced Hes1 expression and exhibited anticancer effects in pulmonary carcinoid tumor cells, a cell type in which the upregulated Notch/Hes1 signaling plays a tumor suppressive role. Treatment of HCT-116 cells with compound 12 resulted in Hes1 downregulation and antitumor effects.

Topics: Aminoacridines; Aniline Compounds; Antineoplastic Agents; Basic Helix-Loop-Helix Transcription Factors; Carcinoid Tumor; Cell Line, Tumor; Colonic Neoplasms; Coumarins; Down-Regulation; HCT116 Cells; Homeodomain Proteins; Humans; Receptors, Notch; Signal Transduction; Small Molecule Libraries; Transcription Factor HES-1; Up-Regulation

Gastrointestinal (GI) carcinoid cells secrete multiple neuroendocrine (NE) markers and hormones including 5-hydroxytryptamine and chromogranin A. We were interested in determining whether activation of the Notch1 signal transduction pathway in carcinoid cells could modulate production of NE markers and hormones. Human pancreatic carcinoid cells (BON cells) were stably transduced with an estrogen-inducible Notch1 construct, creating BON-NIER cells. In the present study, we found that Notch1 is not detectable in human GI carcinoid tumor cells. The induction of Notch1 in human BON carcinoid cells led to high levels of functional Notch1, as measured by CBF-1 binding studies, resulting in activation of the Notch1 pathway. Similar to its developmental role in the GI tract, Notch1 pathway activation led to an increase in hairy enhancer of split 1 (HES-1) protein and a concomitant silencing of human Notch1/HES-1/achaete-scute homolog 1. Furthermore, Notch1 activation led to a significant reduction in NE markers. Most interestingly, activation of the Notch1 pathway caused a significant reduction in 5-hydroxytryptamine, an important bioactive hormone in carcinoid syndrome. In addition, persistent activation of the Notch1 pathway in BON cells led to a notable reduction in cellular proliferation. These results demonstrate that the Notch1 pathway, which plays a critical role in the differentiation of enteroendocrine cells, is highly conserved in the gut. Therefore, manipulation of the Notch1 signaling pathway may be useful for expanding the targets for therapeutic and palliative treatment of patients with carcinoid tumors.

Topics: Basic Helix-Loop-Helix Transcription Factors; Blotting, Western; Carcinoid Tumor; Cell Line, Tumor; Chromogranin A; Chromogranins; DNA-Binding Proteins; Gastrointestinal Neoplasms; Genes, Reporter; Homeodomain Proteins; Humans; Immunoglobulin J Recombination Signal Sequence-Binding Protein; Luciferases; Nuclear Proteins; Phosphopyruvate Hydratase; Receptor, Notch1; Receptors, Cell Surface; Serotonin; Signal Transduction; Synaptophysin; Transcription Factor HES-1; Transcription Factors

The Notch1-signaling pathway has been shown to regulate the differentiation and growth of carcinoid tumor cells. However, the molecules that mediate Notch1 signaling, as well as their potential roles in regulating the growth of carcinoid tumors, have not been characterized. We and others have shown previously that the transcription factor Hairy Enhancer of Split-1 (HES-1) is upregulated in response to Notch1 signaling, demonstrating that it is a Notch1 effector. We hypothesized that HES-1 may be the essential downstream factor in Notch1-mediated growth regulation of carcinoid tumors.. H727 carcinoid tumor cells were transduced stably with a doxycycline-inducible HES-1 construct, creating H727-HES-1 cells. H727-TRE (vector-only control) and H727-HES-1 cells were then treated with varying concentrations of doxycycline to achieve increasing levels of HES-1 protein expression. Cell proliferation was determined with the use of a cell viability assay.. Treatment of H727-HES-1 cells with increasing dosages of doxycycline resulted in dose-dependent increases in HES-1 protein by Western blot analysis. Importantly, induction of HES-1 in carcinoid tumor cells led to suppression of tumor cellular proliferation. Moreover, the degree of carcinoid growth inhibition appeared to be proportional to the level of HES-1 induction.. HES-1 alone can regulate the growth of carcinoid tumor cells. Furthermore, these results suggest that HES-1 may be the critical downstream effector in the Notch1-signaling pathway.

Topics: Basic Helix-Loop-Helix Transcription Factors; Carcinoid Tumor; Cell Culture Techniques; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Doxycycline; Homeodomain Proteins; Humans; Lung Neoplasms; Receptor, Notch1; Transcription Factor HES-1