Project description:Several copy number altered regions (CNA) have been identified in the genome of cervical cancer, especially amplifications of 3q and 5p. However, the contribution of those alterations to cervical carcinogenesis is still a matter of debate, since genome-wide, there is a lack of correlation between CNAs and gene expression. In this study, we investigated whether the CNAs in cell lines (CaLo, CasKi, HeLa, SiHa), at a gene-by-gene level, are related to changes in gene expression. On average 19.2% of the whole genome of cell lines had CNA. However, only 2.4% consisted of minimal recurrent regions (MRR), common to all cell lines. Whereas 3q had just some sparse common gains (13%), 5p was entirely duplicated recurrently. Genome-wide, only 11% of genes located in CNAs changed gene expression. In contrast, the rate increased over 3 fold times in MRRs. Chr 5p was confirmed entirely amplified by FISH. In spite of this, at most 32.9% of the explored genes in 5p (n=202) were de-regulated. In 3q, the rate was just 11.8%. Even in 3q26, which had five MRRs and 38.7% of SNPs was gained recurrently, the rate rose slightly to 13.6% (10 out of 73). Interestingly, up to 16% of de-regulated genes in 5p and 80% in 3q26 were down-regulated, suggesting additional factors are involved in gene repression. The de-regulated genes in 3q and 5p were found in clusters, suggesting local chromatin factors may also influence gene expression. In regions amplified discontinuously, the rate of down-regulated genes rose steadily as the number of amplified SNPs increased (p<0.01, Spearman's correlation). This suggests partial gene amplification as a mechanism of silencing gene expression. Additional genes were identified up- or down-regulated in 5p and 3q, which could be involved in cervical carcinogenesis, especially implicated in apoptosis. Those include CLPTM1L, AHRR, PDCD6 and DAP in 5p and TNFSF10 and ECT2 in 3q. Overall, the gene expression and copy number profiles suggest other factors, like epigenetic or chromatin domains, may influence gene expression within the entirely amplified genome segments. Further studies are needed to elucidate how these mechanisms regulate gene expression. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from cell lines or peripheral blood samples. Copy number analysis of Affymetrix 100K SNP arrays was performed for 4 cervical cancer cell lines. DNA from 38 healty women were used as references for copy number inference.

Project description:Several copy number altered regions (CNA) have been identified in the genome of cervical cancer, especially amplifications of 3q and 5p. However, the contribution of those alterations to cervical carcinogenesis is still a matter of debate, since genome-wide, there is a lack of correlation between CNAs and gene expression. In this study, we investigated whether the CNAs in cell lines (CaLo, CasKi, HeLa, SiHa), at a gene-by-gene level, are related to changes in gene expression. On average 19.2% of the whole genome of cell lines had CNA. However, only 2.4% consisted of minimal recurrent regions (MRR), common to all cell lines. Whereas 3q had just some sparse common gains (13%), 5p was entirely duplicated recurrently. Genome-wide, only 11% of genes located in CNAs changed gene expression. In contrast, the rate increased over 3 fold times in MRRs. Chr 5p was confirmed entirely amplified by FISH. In spite of this, at most 32.9% of the explored genes in 5p (n=202) were de-regulated. In 3q, the rate was just 11.8%. Even in 3q26, which had five MRRs and 38.7% of SNPs was gained recurrently, the rate rose slightly to 13.6% (10 out of 73). Interestingly, up to 16% of de-regulated genes in 5p and 80% in 3q26 were down-regulated, suggesting additional factors are involved in gene repression. The de-regulated genes in 3q and 5p were found in clusters, suggesting local chromatin factors may also influence gene expression. In regions amplified discontinuously, the rate of down-regulated genes rose steadily as the number of amplified SNPs increased (p<0.01, Spearman's correlation). This suggests partial gene amplification as a mechanism of silencing gene expression. Additional genes were identified up- or down-regulated in 5p and 3q, which could be involved in cervical carcinogenesis, especially implicated in apoptosis. Those include CLPTM1L, AHRR, PDCD6 and DAP in 5p and TNFSF10 and ECT2 in 3q. Overall, the gene expression and copy number profiles suggest other factors, like epigenetic or chromatin domains, may influence gene expression within the entirely amplified genome segments. Further studies are needed to elucidate how these mechanisms regulate gene expression.

Project description:Several copy number altered regions (CNA) have been identified in the genome of cervical cancer, especially amplifications of 3q and 5p. However, the contribution of those alterations to cervical carcinogenesis is still a matter of debate, since genome-wide, there is a lack of correlation between CNAs and gene expression. In this study, we investigated whether the CNAs in cell lines (CaLo, CasKi, HeLa, SiHa), at a gene-by-gene level, are related to changes in gene expression. On average 19.2% of the whole genome of cell lines had CNA. However, only 2.4% consisted of minimal recurrent regions (MRR), common to all cell lines. Whereas 3q had just some sparse common gains (13%), 5p was entirely duplicated recurrently. Genome-wide, only 11% of genes located in CNAs changed gene expression. In contrast, the rate increased over 3 fold times in MRRs. Chr 5p was confirmed entirely amplified by FISH. In spite of this, at most 32.9% of the explored genes in 5p (n=202) were de-regulated. In 3q, the rate was just 11.8%. Even in 3q26, which had five MRRs and 38.7% of SNPs was gained recurrently, the rate rose slightly to 13.6% (10 out of 73). Interestingly, up to 16% of de-regulated genes in 5p and 80% in 3q26 were down-regulated, suggesting additional factors are involved in gene repression. The de-regulated genes in 3q and 5p were found in clusters, suggesting local chromatin factors may also influence gene expression. In regions amplified discontinuously, the rate of down-regulated genes rose steadily as the number of amplified SNPs increased (p<0.01, Spearman's correlation). This suggests partial gene amplification as a mechanism of silencing gene expression. Additional genes were identified up- or down-regulated in 5p and 3q, which could be involved in cervical carcinogenesis, especially implicated in apoptosis. Those include CLPTM1L, AHRR, PDCD6 and DAP in 5p and TNFSF10 and ECT2 in 3q. Overall, the gene expression and copy number profiles suggest other factors, like epigenetic or chromatin domains, may influence gene expression within the entirely amplified genome segments. Further studies are needed to elucidate how these mechanisms regulate gene expression. We analyzed four cervical cancer cell lines and normal exocervix tissue from 10 healthy female subjects using the Affymetrix Human Exon 1.0 ST platform. Array data was processed by Affymetrix Exon Array Computational Tool. Biological replicates were performed for the cell lines. biological replicate: Calo-a, Calo-b biological replicate: Caski-a, Caski-b biological replicate: Hela-a, Hela-b biological replicate: Siha-a, Siha-b

Project description:The contribution of copy number (CN)-altered genes in cervical carcinogenesis is unknown owing to a lack of correlation with gene expression. We mapped CN-altered genes in 31 cervical cancers (CCs), and investigated the expression of 21,000 genes in 55 CCs using microarrays. Biological processes associated with genes deregulated by gene dosage and the relationship between gene dosage and patient survival were investigated. CN-altered genome (CN-AG) percentages varied widely among tumors from 0% to 32.2% (mean = 8.1 ± 8.9). Tumors were classified as low (mean = 0.5 ± 0.6, n = 11), medium (mean = 5.4 ± 2.4, n = 10), or high (mean = 19.2 ± 6.6, n = 10) CN. The highest %CN-AG was found in 3q, which contributed an average of 55% of all CN alterations. Genome-wide, only 5.3% of CN-altered genes were deregulated by gene dosage; by contrast, the rate in fully duplicated 3q was twice as high. Amplification of 3q explained 23.6% of deregulated genes in whole tumors (r2 = 0.236, p = 0.006; analysis of variance), including those in 3q and other chromosomes. A total of 862 genes were deregulated exclusively in high-CN tumors, but only 22.9% were CN altered. This result suggests that the remaining genes are not deregulated directly by gene dosage but by mechanisms induced in trans by CN-altered genes. Anaphase-promoting complex/cyclosome (APC/C)-dependent proteasome proteolysis, glycolysis, and apoptosis were upregulated, whereas cell adhesion and angiogenesis were downregulated exclusively in high-CN tumors. The high %CN-AG and upregulated gene expression profiles of APC/C-proteasome-dependent proteolysis and glycolysis were associated with poor patient survival, although only the first 2 correlations were statistically significant (p < 0.05, log-rank test). The data suggest that inhibitors of APC/C-dependent proteasome proteolysis and glycolysis may be useful treatments in these patients. In this study 31 tumors and 25 reference controls were used for analysis of copy number alterations using the 500K microarray. The results obtained from 500K array analysis were validated in 15 of the 31 tumors with a higher density microarray (Cytoscan HD). For the analysis of gene expression 55 cervical tumors (27 of them belong to the group of 31 tumors analyzed for copy number) and 17 exocervical controls were used. Please note that the sample R397 in the CytoScanHD_Array set corresponds to the R392 sample in the other data sets (due to an error in file name).

Dataset Information

Amplified genes are not necessarily over expressed, they can be unchanged or down regulated in cervical cancer cell lines [SNP array data]

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