Specific inhibitor of Notch­3 enhances the sensitivity of NSCLC cells to gemcitabine.

Notch­3 is a receptor of the Notch signaling pathway and plays an important role in regulating self­renewal, differentiation and apoptosis in cancer cells. Overexpression of Notch­3 has been proved to be associated with resistance to gemcitabine (GEM) and poor patient prognosis for various malignant tumors. In the present study, two non­small cell lung cancer (NSCLC) cell lines, H1299 and A549, were induced with GEM for two months and then were treated with various concentrations of a Notch signaling blocker, N­[N­(3,5­difluorophenacetyl)­L­alanyl]­S­phenylglycine t­butyl ester (DAPT), with the goal of reducing expression of Notch intracellular domain 3 (NICD3). Both cell lines were subsequently treated with either DAPT or DAPT combined with GEM and then viability, apoptosis, colony formation and cell count assays were performed. DAPT treatment effectively downregulated the expression of NICD3 in both cell lines. DAPT combined with GEM also significantly reduced the percentage of viable cells in both cell lines, while increasing the percentage of apoptotic cells, compared with GEM alone. In the clonogenicity assays, the combination of DAPT and GEM led to a decrease in clone numbers and significantly greater inhibition of the H1299 and A549 cells compared to treatment with DAPT or GEM alone. Meanwhile, levels of the apoptosis­related proteins, Bcl­2 and Bax, were found to be affected by the various treatments. Thus Notch­3 appears to be a promising target for gene therapy and DAPT is able to mediate a strong antitumor effect in NSCLC cells that overexpress Notch­3. Further studies of a combined treatment regimen with DAPT and GEM are warranted and may provide greater efficacy and safety in the treatment of NSCLC patients.

Notch signaling molecules as prognostic biomarkers for non-small cell lung cancer.

Notch family proteins have been reported to be associated with the initiation and development of various types of tumors. The present study used a prospective design to investigate the role of Notch proteins as novel biomarkers that are capable of predicting the survival outcome for patients with non-small cell lung cancer (NSCLC). The protein expression of Notch 1, Notch 3 and their ligands, Jagged 1 and Delta-like 4, was examined using immunohistochemistry in NSCLC tissues and adjacent non-cancerous lung tissues from 101 patients who underwent surgical treatment. The expression was also correlated with clinicopathological parameters and overall survival (OS). High Notch 1 protein expression was observed in 55.4% (56/101) of NSCLC samples and high Notch 3 expression was observed in 53.5% (54/101). The nuclear expression of Notch 3 was significantly associated with the lymph node status (P=0.0026) and tumor-node-metastasis (TNM) stage (P<0.0001), while the coexpression of Notch 1 plus Notch 3 was associated with lymph node status (P=0.0056), TNM stage (P=0.0001) and the histological grading (P=0.0359). In the survival analyses, the high expression of Notch 1 and Notch 3 exhibited an additive effect toward a poorer OS compared with a subtype with low coexpression for the two proteins (P<0.001), with high nuclear Notch 3 expression in the NSCLC patients maintaining independent prognostic significance for the outcome on multivariate analysis. These data further demonstrate a central role for Notch signaling in NSCLC and the significance of Notch 3 as a prognostic indicator of a poorer survival for patients with resected NSCLC.

Notch3 overexpression associates with poor prognosis in human non-small-cell lung cancer.

Notch3 receptor is one of the mammalian Notch family receptors (Notch1-4) which plays an important role in the regulation of cellular proliferation, differentiation, and apoptosis. Overexpression of Notch3 is associated with tumorigenesis. In order to assess the expression of Notch3 in Chinese non-small-cell lung cancer (NSCLC) patients and determine its association with prognosis, we designed a prospective study with five years of follow-up to evaluate Notch3 expression in NSCLC tissues and adjacent non-cancerous normal lung tissues from 131 patients undergoing surgical treatment by immunohistochemistry and western blot analysis. Notch3 had high expression in 67 of 131 cases of NSCLC (51.1 %), which was significantly higher than in adjacent noncancerous lung tissues. Moreover, Notch3 overexpression was significantly correlated with TNM stage (P = 5.41e-07 in squamous cell carcinoma, P = 5.338e-07 in adenocarcinoma) and lymph node metastasis (P = 0.00764 in squamous cell carcinoma, P = 0.01491 in adenocarcinoma). Kaplan-Meier survival analysis showed that the overall survival times in patients expressing Notch3 in NSCLC were shorter. Multivariate analysis further demonstrated that Notch3 was an independent prognostic factor for patients with NSCLC. Therefore, Notch3 might be a useful biomarker to predict the prognosis of patients with NSCLC.