Project description:Phosphotyrosine status were compared between colorectal cancer cells which is sensitive or resistant to Cetuximab. Activated kinases in resistant cells were examined as targets to overcome the resistance.
Project description:Cetuximab is an epidermal growth factor receptor (EGFR)-blocking antibody approved for treatment of metastatic colorectal cancer. We examined differences in global gene expression between the syngeneic DiFi colorectal cancer cells, and a subline of DiFi cells with acquired resistance to cetuximab (DiFi5). We used Affymetrix HG-U133A array to compare the expression pattern of genes that are up-regulated or down-regulated between the parental DiFi colorectal cancer cells and the cetuximab-resistant DiFi5 cells.
Project description:Cetuximab is an epidermal growth factor receptor (EGFR)-blocking antibody approved for treatment of metastatic colorectal cancer. We examined differences in global gene expression between the syngeneic DiFi colorectal cancer cells, and a subline of DiFi cells with acquired resistance to cetuximab (DiFi5). We used Affymetrix HG-U133A array to compare the expression pattern of genes that are up-regulated or down-regulated between the parental DiFi colorectal cancer cells and the cetuximab-resistant DiFi5 cells. We generated a cetuximab-resistant DiFi subline, termed DiFi5, by chronic exposure of parental DiFi cells to serially increased doses of cetuximab (from 0.5 nM to 5 nM) for over 1 year. The resulting DiFi5 subline exhibits significant resistance to cetuximab-induced apoptosis. After we confirmed that the phenotype was stable over a period of time of more than 6 months, the RNA from DiFi and DiFi5 cells were extracted and hybridized to an Affymetrix HG-U133A array according to the manufacturerâs instructions. Following the hybridization, the array was scanned using a laser confocal scanner, and microarray image data were analyzed using DNA-Chip Analyzer (dChip), version 1.3, by the Sequencing and Microarray Facility at MD Anderson Cancer Center.
Project description:10 cell lines (five cetuximab sensitive and five cetuximab resistant) were selected for gene copy number array analysis on the Affymetrix SNP 6.0 platform. 39 protein coding genes were amplified in cetuximab resistant cells and normal in sensitive cells, all present on genomic regions 11q22.1 or 5p13-15. Five genes were selected for quantitative PCR verification, namely, YAP1 and TRPC6 (11q22.1) and PDCD6, TPPP, and PTGER4 (5p13-15). An extended panel of totally 10 cetuximab resistant and 10 sensitive cell lines verified that YAP1 amplified cells are cetuximab resistant. YAP1 gene amplification was highly correlated to the YAP1 mRNA expression, which was significantly higher in cetuximab resistant cells than in sensitive. YAP1 downregulation resulted in increased cetuximab sensitivity in one of two cetuximab resistant cell lines investigated and growth inhibition in another. We conclude that YAP1 is a marker for cetuximab resistance in head and neck cancer. head and neck cancer cell lines with established cetuximab response were selected. 5 cetuximab resistant cell lines and 5 cetuximab sensitive cell lines were selected for gene genome wide gene copy number analysis on the Affymetrix SNP6.0 array
Project description:Anti-EGFR antibodies are effective in therapies for late-stage colorectal cancer (CRC); however, many tumours are unresponsive or develop resistance. We performed genomic analysis of intrinsic and acquired resistance to anti-EGFR therapy in prospectively collected tumour samples from 25 CRC patients receiving cetuximab (an EGFR inhibitor). Of 25 CRC patients, 13 displayed intrinsic resistance to cetuximab; 12 were intrinsically sensitive. We obtained six re-biopsy samples at acquired resistance from the intrinsically sensitive patients. NCOA4–RET and LMNA–NTRK1 fusions and NRG1 and GNAS amplifications were found in intrinsic-resistant patients. In cetuximab-sensitive patients, we found KRAS K117N and A146T mutations in addition to BRAF V600E, AKT1 E17K, PIK3CA E542K, and FGFR1 or ERBB2 amplifications. The comparison between baseline and acquired-resistant tumours revealed an extreme shift in variant allele frequency of somatic variants, suggesting that cetuximab exposure dramatically selected for rare resistant subclones that were initially undetectable. There was also an increase in epithelial-to-mesenchymal transition at acquired resistance, with a reduction in the immune infiltrate. Furthermore, characterization of an acquired-resistant, patient-derived cell line showed that PI3K/mTOR inhibition could rescue cetuximab resistance. Thus, we uncovered novel genomic alterations that elucidate the mechanisms of sensitivity and resistance to anti-EGFR therapy in metastatic CRC patients.
Project description:10 cell lines (five cetuximab sensitive and five cetuximab resistant) were selected for gene copy number array analysis on the Affymetrix SNP 6.0 platform. 39 protein coding genes were amplified in cetuximab resistant cells and normal in sensitive cells, all present on genomic regions 11q22.1 or 5p13-15. Five genes were selected for quantitative PCR verification, namely, YAP1 and TRPC6 (11q22.1) and PDCD6, TPPP, and PTGER4 (5p13-15). An extended panel of totally 10 cetuximab resistant and 10 sensitive cell lines verified that YAP1 amplified cells are cetuximab resistant. YAP1 gene amplification was highly correlated to the YAP1 mRNA expression, which was significantly higher in cetuximab resistant cells than in sensitive. YAP1 downregulation resulted in increased cetuximab sensitivity in one of two cetuximab resistant cell lines investigated and growth inhibition in another. We conclude that YAP1 is a marker for cetuximab resistance in head and neck cancer.
Project description:Cetuximab (Erbitux) is an antibody drug against EGFR and commonly used in late stage HNSCC and metastatic colorectal cancer. The oncogenic mutation of certain genes are known to drive Cetuximab resistance such as K-RAS or b-RAF mutation. The aberrant activation of signaling pathways in the presence of Cetuximab treatment to overcome cellular stress contribute to acquired resistance to Cetuximab as well. To better understand the mechanisms and molecular patterns of Cetuximab resistant cells, the Cetuximab resistant cells are trained for examining the gene expression profile. The gene expression array is used for identify the molecular signature governing the Cetuximab resitance.
Project description:To determine the mechanism of cetuximab-resistance in head and neck cancer, a cetuximab-sensitive cell line (SCC1) and its cetuximab-resistant derivative (1Cc8) were analyzed for differentially expressed genes using DNA microarrays. 900 differentially expressed genes were found using the statistical cut-off point of one-way ANOVA with FDR less than 1%.