Quantitative Analysis of Alternative Spliced Variants in HNSCC
Ontology highlight
ABSTRACT: Alternative splicing of pre-mRNA generates protein diversity and has been linked to cancer progression and drug response. Exon microarray technology enables genome-wide quantication of expression levels for the majority of exons and facilitates the discovery of alternative splicing events. Analysis of exon array data is more challenging than gene expression data and there is a need for reliable quantication of exons and alternative spliced variants. We introduce a novel, computationally efficient methodology, MEAP, for exon array data preprocessing, analysis and visualization. We compared MEAP with other preprocessing methods, and validation of the results show that MEAP produces reliable quantication of exons and alternative spliced variants. Analysis of data from head and neck squamous cell carcinoma (HNSCC) cell lines revealed several variants associated with 11q13 amplication, which is a predictive marker of metastasis and decreased survival in HNSCC patients. Together these results demonstrate the utility of MEAP in suggesting novel experimentally testable predictions. Thus, in addition to novel methodology to process large-scale exon array data sets, our results provide several HNSCC candidate genes for further studies. We analyzed 15 samples using the Affymetrix Human Exon 1.0 ST platform, of which 7 samples have 11q13 amplification. Array data was preprocessed by using Multiple Exon Array Processing (MEAP).
Project description:Alternative splicing of pre-mRNA generates protein diversity and has been linked to cancer progression and drug response. Exon microarray technology enables genome-wide quantication of expression levels for the majority of exons and facilitates the discovery of alternative splicing events. Analysis of exon array data is more challenging than gene expression data and there is a need for reliable quantication of exons and alternative spliced variants. We introduce a novel, computationally efficient methodology, MEAP, for exon array data preprocessing, analysis and visualization. We compared MEAP with other preprocessing methods, and validation of the results show that MEAP produces reliable quantication of exons and alternative spliced variants. Analysis of data from head and neck squamous cell carcinoma (HNSCC) cell lines revealed several variants associated with 11q13 amplication, which is a predictive marker of metastasis and decreased survival in HNSCC patients. Together these results demonstrate the utility of MEAP in suggesting novel experimentally testable predictions. Thus, in addition to novel methodology to process large-scale exon array data sets, our results provide several HNSCC candidate genes for further studies.
Project description:delta-Np63 is highly expressed in squamous cell carcinoma of the head and neck (HNSCC). To evaluate its function in HNSCC we depleted delta-Np63 by siRNAs in the HNSCC cell line UT-SCC-74A. The transcriptome was analysed by cDNA microarray.
Project description:Although Epidermal growth factor receptor (EGFR) is overexpressed in 90% of Head and neck squamous cell carcinoma (HNSCC) patients. Clinical trials with EGFR-targeted small molecule inhibitors such as erlotinib have shown a modest activity in recurrent or advanced HNSCC. To investigate the acquired mechanisms of erlotinib resistance we employed SILAC-based total proteomic analysis of an isogenic pair of erlotinib sensitive (SCC-S) and resistant (SCC-R) HNSCC cell line. This resulted in the identification of 5,427 proteins of which 532 proteins were overexpressed and 527 proteins were downregulated in SCC-R cells as compared to SCC-S cells (≥2 fold). Several proteins known to mediate erlotinib resistance in HNSCC and lung cancer were found to be dysregulated. Bioinformatics analysis of differentially expressed proteins showed enrichment of proteins involved in focal adhesion kinase (FAK) pathway downstream of EGFR. We identified CUB-domain containing protein 1 (CDCP1) and integrin β1 as upstream regulators of FAK signalling pathway to be overexpressed. We further demonstrated that CDCP1 and FAK can be targeted in combination as an alternative to erlotinib in HNSCC.
Project description:Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase is overexpressed in 90% of Head and neck squamous cell carcinoma (HNSCC) patients. Clinical trials with EGFR-targeted tyrosine kinase inhibitors such as erlotinib have shown a modest activity in HNSCC alternate mechanisms of resistance are acquired. To investigate these acquired mechanisms of resistance and identify novel therapeutic targets we employed SILAC-based tyrosine phosphoteomic analysis of an isogenic pair of erlotinib sensitive (SCC-S) and resistant (SCC-R) HNSCC cell line. Quantitative phosphotyrosine profiling revealed 98 phosphopeptides belonging to 64 proteins and 66 phosphopeptides belonging to 52 proteins to be hyper and hypophosphorylated (≥2 fold) in SCC-R cells, respectively. Several proteins such MET proto-oncogene, receptor tyrosine kinase (MET) and CRK like proto-oncogene, adaptor protein (CRKL) known to mediate erlotinib resistance in HNSCC and lung cancer were found to be dysregulated. Bioinformatics analysis of differentially phosphorylated proteins showed enrichment of proteins involved in focal adhesion kinase (FAK) pathway downstream of EGFR. We identified and validated activation of several phosphorylation sites of protein tyrosine kinase 2 (PTK2) in SCC-R cells and its downstream targets. We further demonstrated that CUB-domain containing protein 1 (CDCP1), an upstream regulator of PTK2 activity and PTK2 can be targeted in combination as an alternative to erlotinib in HNSCC.
Project description:Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase is overexpressed in 90% of Head and neck squamous cell carcinoma (HNSCC) patients. Clinical trials with EGFR-targeted tyrosine kinase inhibitors such as erlotinib have shown a modest activity in HNSCC alternate mechanisms of resistance are acquired. To investigate these acquired mechanisms of resistance and identify novel therapeutic targets we employed whole exome sequencing of an isogenic pair of erlotinib sensitive (SCC-S) and resistant (SCC-R) HNSCC cell line. We observed single nucleotide variations and copy number alterations in genes related to RAS-RAF-MEK-ERK pathway. To assess the effects of these variations on cellular kinome and we employed SILAC-based phosphoproteomic analysis of SCC-S and SCC-R cell lines. Quantitative phosphoprotein profiling led to identification of 5558 unique phosphopeptides and 5025 unique phosphosites corresponding to 2344 proteins. We observed, 903 phosphopeptides belonging to 579 proteins and 518 phosphopeptides belonging to 368 proteins to be hyper and hypophosphorylated (≥2 fold) in SCC-R cells, respectively. Bioinformatics analysis of differentially phosphorylated proteins showed enrichment of proteins involved in MAPK pathway downstream of EGFR. We identified and validated activation of proteins related to MAPK pathway and its downstream targets in SCC-R cells. We further demonstrated that MAP2K1 inhibitor can be used as an alternative to erlotinib in HNSCC.
Project description:To clarify the functional properties of FUS, we established the differentially expressed alternative exons in FUS-silenced primary motor neurons by using exon-sensitive microarray technology. To clarify the functional properties of FUS, we established the differentially expressed alternative exons in FUS-silenced primary glial cells by using exon-sensitive microarray technology. To clarify the functional properties of FUS, we established the differentially expressed alternative exons in FUS-silenced primary cerebellar neurons by using exon-sensitive microarray technology.
Project description:Alternative 3’-terminal exons, which use intronic polyadenylation sites, are generally unconserved and lowly expressed, while the main gene products end in the last exon of genes. In this study, we discover a class of human genes, where the last exon appeared recently during evolution, and the major gene product uses an alternative 3’-terminal exon corresponding to the ancestral last exon of the gene. This novel class of alternative 3’-terminal exons are down-regulated on a large scale by doxorubicin, a cytostatic drug targeting topoisomerase II, and play a role in cell cycle regulation, including centromere-kinetochore assembly. The RNA-binding protein, HuR/ELAVL1 is a major regulator of this specific set of alternative 3’-terminal exons. HuR binding to the alternative 3’-terminal exon in the pre-messenger RNA promotes its splicing, and is reduced by topoisomerase inhibitors. These findings provide new insights into the evolution, function and molecular regulation of alternative 3’-terminal exons.
Project description:Tumor budding (TB) is a well-established prognostic biomarker in HPV-negative head and neck squamous cell carcinoma (HNSCC) and an emerging prognostic biomarker in HPV-positive HNSCC. The molecular determinants and mechanisms underlying TB are incompletely understood. Here, we profile an in-house cohort of HPV-negative HNSCCs by MS-based proteomics to uncovered molecular correlates of TB in HNSCC.
Project description:In this study we performed a genome wide analysis of the entire complement of mRNAs in clear cell renal cell carcinomas (ccRCC) by means of the Affymetrix Exon Array platform. The analyses were performed both at gene and exon level. Under our parameters over 2,000 genes resulted differentially expressed, and about 250 genes resulted alternative spliced showing differential inclusion of specific cassette exons comparing tumor and non tumoral tissues.
Project description:Alternative 3M-bM-^@M-^Y-terminal exons, which use intronic polyadenylation sites, are generally unconserved and lowly expressed, while the main gene products end in the last exon of genes. In this study, we discover a class of human genes, where the last exon appeared recently during evolution, and the major gene product uses an alternative 3M-bM-^@M-^Y-terminal exon corresponding to the ancestral last exon of the gene. This novel class of alternative 3M-bM-^@M-^Y-terminal exons are down-regulated on a large scale by doxorubicin, a cytostatic drug targeting topoisomerase II, and play a role in cell cycle regulation, including centromere-kinetochore assembly. The RNA-binding protein, HuR/ELAVL1 is a major regulator of this specific set of alternative 3M-bM-^@M-^Y-terminal exons. HuR binding to the alternative 3M-bM-^@M-^Y-terminal exon in the pre-messenger RNA promotes its splicing, and is reduced by topoisomerase inhibitors. These findings provide new insights into the evolution, function and molecular regulation of alternative 3M-bM-^@M-^Y-terminal exons. 6 samples of MCF7 cells exposed to different treatments were analyzed: 3 x control_6 hours; 3 x doxorubicin_6 hours.