n-(n-(3-5-difluorophenacetyl)alanyl)phenylglycine-tert-butyl-ester and Uterine-Cervical-Neoplasms

The Notch signaling pathway plays important roles in tumorigenesis in a context-dependent manner. In human cervical cancer, alterations in Notch signaling have been reported, and both tumor-suppressing and tumor-promoting roles of Notch signaling have been proposed; however, the precise molecular mechanisms governing these roles in cervical cancer remain controversial. MAML is a transcriptional co-activator originally identified by its role in Notch signaling. Recent evidence suggests that it also plays a role in other signaling pathways, such as the p53 and β-catenin pathways. MAML is required for stable formation of Notch transcriptional complexes at the promoters of Notch target genes. Chromosomal translocations affecting MAML have been shown to promote tumorigenesis. In this study, we used a truncated dominant-negative MAML1 (DN-MAML) to investigate the role of MAML in HPV-positive cervical cancer cell lines. Three human cervical cancer cell lines (HeLa, SiHa and CaSki) expressed all Notch receptors and the Notch target genes Hes1 and MAML1. Among these 3 cell lines, constitutive appearance of cleaved Notch1 was found only in CaSki cells, which suggests that Notch1 is constitutively activated in this cell line. Gamma secretase inhibitor (GSI) treatment, which suppresses Notch receptor activation, completely abrogated this form of Notch1 but had no effect on cell viability. Overexpression of DN-MAML by retroviral transduction in CaSki cells resulted in significant decreases in the mRNA levels of Hes1 and Notch1 but had no effects on the levels of MAML1, p53 or HPV E6/E7. DN-MAML expression induced increased viability of CaSki cells without any effect on cell cycle progression or cell proliferation. In addition, clonogenic assay experiments revealed that overexpression of DN-MAML resulted in increased colony formation compared to the overexpression of the control vector. When the status of the NF-κB pathway was investigated, CaSki cells overexpressing DN-MAML exhibited loss of phospho-IκBα, decreased total IκBα and nuclear localization of NF-κB p65, which suggests that the NF-κB pathway is hyperactivated. Furthermore, increased level of cleaved Notch1 was detected when DN-MAML was expressed. When DN-MAML-overexpressing cells were treated with GSI, significantly decreased cell viability was observed, indicating that inhibition of Notch signaling using GSI treatment and DN-MAML expression negatively affects cell viability. Taken together, targeting Notch

Topics: Amyloid Precursor Protein Secretases; Basic Helix-Loop-Helix Transcription Factors; Cell Line, Tumor; Cell Survival; Dipeptides; DNA-Binding Proteins; Dose-Response Relationship, Drug; Female; HeLa Cells; Homeodomain Proteins; Humans; NF-kappa B; Receptors, Notch; Signal Transduction; Structure-Activity Relationship; Transcription Factor HES-1; Transcription Factors; Uterine Cervical Neoplasms

To study the expression and clinical significance of Notch intracellular domain (NICD) in cervical cancer and the effects of N-[N-(3,5-difluorophenyl)acetyl-L-alanyl]-S-phenyl glycine t-butyl ester (DAPT), a gamma-secretase inhibitor on the proliferation and apoptosis of cervical cancer cell lines.. Western blot was used to detect the expression of NICD in the tissues of 40 cervical cancers and 21 normal cervix and its relationship with clinical features of cervical cancer was also analyzed. Proliferation of SiHa and HeLa cervical cells was determined by methyl thiazolyl tetrazolium (MTT) assay, cell cycles and apoptosis and index of proliferation were detected by flow cytometry method. The expression of NICD in SiHa and HeLa cells incubated with DAPT was detected by western blot.. The expression level of NICD in cervical cancers was significantly higher than that of normal cervical tissues (1.237 +/- 0.353 vs 0.938 +/- 0.105, P < 0.05). The NICD expression was higher in cervical cancers with high grade, lymph node involvement and parametrial invasion than that with low-middle grade (1.496 +/- 0.540 vs 1.150 +/- 0.216), without lymph node involvement (1.419 +/- 0.532 vs 1.159 +/- 0.210) and no parametrial invasion (1.718 +/- 0.710 vs 1.183 +/- 0.258), respectively (all P < 0.05). The expression of NICD in cervical adenocarcinoma was higher than that of squamous cell cancer (1.463 +/- 0.395 vs 1.162 +/- 0.187, P < 0.05). After SiHa and HeLa cells were incubated with DAPT, NICD expression was significantly lower than that in control (P < 0.05). The effects of DAPT inhibited the proliferation and prompted the apoptosis of SiHa and HeLa cells was depended on its concentrations and times.. NICD may play a key role in the occurrence and progress of cervical cancer. The mechanism of DAPT inhibited the proliferation and prompted the apoptosis of SiHa and HeLa cells may be due to decreased the formation of NICD.

Topics: Adult; Aged; Amyloid Precursor Protein Secretases; Antineoplastic Agents; Apoptosis; Blotting, Western; Carcinoma, Squamous Cell; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Dipeptides; Dose-Response Relationship, Drug; Female; Flow Cytometry; HeLa Cells; Humans; Middle Aged; Neoplasm Staging; Receptors, Notch; Uterine Cervical Neoplasms; Young Adult