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Targeting specific regions of the Notch3 ligand-binding domain induces apoptosis and inhibits tumor growth in lung cancer.

ABSTRACT: Like many signaling pathways in development, the Notch receptor pathway plays an important role in cancer pathobiology when it is dysregulated. Potential ligand-binding sites within the epidermal growth factor (EGF)-like repeats of Notch1 have been identified, but the ligand-binding domains in Notch3, which is implicated in lung cancer, are not known. In screening a library of 155 peptides representing all 34 EGF-like repeats in Notch3, we discovered two distinct ligand-binding regions involving the 7-10 and 21-22 repeats that are distinct from the putative ligand-binding domain of Notch1. In cell-based assays, peptides from these regions induced apoptosis and reduced expression of the Notch3-dependent gene Hey1. They also bound directly to the Notch ligand Jagged1, suggesting that their mechanism of action involves disrupting interactions between Notch3 and Jagged1. Recombinant Fc fusion peptides engineered for in vivo testing showed that the Notch3 peptides defined could trigger apoptosis and suppress tumor growth in tumor xenograft assays. These findings rationalize a mechanistic approach to lung cancer treatment based on Notch3 receptor-targeted therapeutic development.

SUBMITTER: Lin L

PROVIDER: S-EPMC3210016 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

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Targeting specific regions of the Notch3 ligand-binding domain induces apoptosis and inhibits tumor growth in lung cancer.

Lin Luping L Mernaugh Ray R Yi Fuming F Blum David D Carbone David P DP Dang Thao P TP

Cancer research 20100112 2

Like many signaling pathways in development, the Notch receptor pathway plays an important role in cancer pathobiology when it is dysregulated. Potential ligand-binding sites within the epidermal growth factor (EGF)-like repeats of Notch1 have been identified, but the ligand-binding domains in Notch3, which is implicated in lung cancer, are not known. In screening a library of 155 peptides representing all 34 EGF-like repeats in Notch3, we discovered two distinct ligand-binding regions involving ...[more]

PMID: 20068176

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Project description:Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant small-vessel disease of the brain caused by mutations in the NOTCH3 receptor. The highly stereotyped nature of the mutations, which alter the number of cysteine residues within the epidermal growth factor-like repeats (EGFR), predicts that all mutations share common mechanisms. Prior in vitro assays and genetic studies in the mouse support the hypothesis that common mutations do not compromise canonical Notch3 function but instead convey a non-physiological and deleterious activity to the receptor through the unpaired cysteine residue. Intriguingly, in vitro studies predict that mutations located in the Delta/Serrate/LAG-2 ligand binding domain-(EGFR10-11) may result in a loss of Notch3 receptor function. However, the in vivo relevance and functional significance of this with respect to the pathogenic mechanisms and clinical expression of the disease remain largely unexplored. To ascertain, in vivo, the functional significance of EGFR10-11 mutations, we generated transgenic mice with one representative mutation (C428S) in EGFR10 of Notch3. These mice, like those with a common R90C mutation, developed characteristic arterial accumulation of Notch3 protein and granular osmiophilic material upon aging. By introducing the mutant C428S transgene into a Notch3 null background, we found that, unlike the R90C mutant protein, the C428S mutant protein has lost wild-type Notch3 activity and exhibited mild dominant-negative activity in three different biological settings. From a large prospectively recruited cohort of 176 CADASIL patients, we identified 10 patients, from five distinct pedigrees carrying a mutation in EGFR10 or 11. These mutations were associated with significantly higher Mini-Mental State Examination and Mattis Dementia Rating Scale scores (P < 0.05), when compared with common mutations. Additionally, we found a strong effect of this genotype on the burden of white matter hyperintensities (P < 0.01). Collectively, these results highlight distinctive functional and phenotypic features of EGFR10-11 mutations relative to the common CADASIL mutations. Our findings are compatible with the hypothesis that EGFR10-11 mutations cause the disease through the same gain of novel function as the common mutations, and lead us to propose that reduced Notch3 signalling acts as a modifier of the CADASIL phenotype.

Project description:BackgroundSelenium is an essential trace element in the human body. In epidemiological and clinical studies, Se supplementation significantly reduced the incidence of lung cancer in individuals with low baseline Se levels. The significant action of selenium is based on the selenium-containing protein as a mediator. Of note, the previous studies reported that the expression of selenium-binding protein 1 (SELENBP1) was obviously decreased in many human cancer tissues including non-small cell lung cancer (NSCLC). However, its roles in the origin and development of NSCLC are still unclear.MethodsThe expression of SELENBP1 was measured by qRT-PCR, Western blotting and IHC in our collected clinical NSCLC tissues and cell lines. Next, the CCK-8, colony formation, wound-haeling, Millicell, Transwell, FCM assay, and in vivo xenograft model were performed to explore the function of SELENBP1 in NSCLC. The molecular mechanisms of SELENBP1 were investigated by Western blotting or IF assay.ResultsWe further identified that the expression of SELENBP1 was significantly decreased in NSCLC tissues in TCGA database and 45 out of 59 collected clinical NSCLC tissues compared with adjacent nontumor tissues, as well as in four NSCLC cell lines compared with normal lung cells. Particularly, we unexpectedly discovered that SELENBP1 was obviously expressed in alveolar type 2 (AT-II) cells for the first time. Then, a series of in vitro experiments uncovered that overexpression of SELENBP1 inhibited the proliferation, migration, and invasion of NSCLC cells, and induced cell apoptosis. Moreover, overexpression of SELENBP1 also inhibited growth and induced apoptosis of NSCLC cells in vivo. Mechanistically, we demonstrated that overexpression of SELENBP1 inhibited the malignant characteristics of NSCLC cells in part via inactivating the PI3K/AKT/mTOR signal pathway. Meanwhile, we found that overexpression of SELENBP1 inducing the apoptosis of NSCLC cells was associated with the activation of caspase-3 signaling pathway under nonhigh level of oxidative stress, but overexpression of SELENBP1 facilitating the cell apoptosis might be related to its combining with GPX1 and colocalizing in the nucleus under high level of oxidative stress.ConclusionsOur findings highlighted that SELENBP1 was an important tumor suppressor during the origin and development of NSCLC. It may help to discover novel biomarkers or drug therapy targets for NSCLC.

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Targeting specific regions of the Notch3 ligand-binding domain induces apoptosis and inhibits tumor growth in lung cancer.

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Targeting specific regions of the Notch3 ligand-binding domain induces apoptosis and inhibits tumor growth in lung cancer.

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