Project description:Oxaliplatin as a first-line drug frequently causes the chemo-resistance on colorectal cancer (CRC). N6-methyladenosine (m6A) methylation has been largely acknowledged in multiple biological functions. However, the molecular mechanisms underlying the m6A methylation in modulating anticancer drug resistance in CRC are still obscure. In present study, RNA-seq was conducted to investigate the transcriptome of HCT116, HCT116 cells with oxaliplatin resistance (HCT116R), HCT8 and HCT8 cells with oxaliplatin resistance (HCT8R).
Project description:To explore the mechanisms associated with oxaliplatin resistance, we compared gene expression in xenograft tumors derived from human colorectal cancer tumor cells HCT116 and its oxaliplatin resistant clones (HCT/OHP1 and HCT/OHP5).
Project description:Oxaliplatin resistance frequently leads to therapeutic failure in colorectal cancer (CRC). Increasing evidence has shown that noncoding RNAs (ncRNAs) play pivotal roles in chemoresistance of CRC. However, the roles and mechanisms of ncRNAs in oxaliplatin resistance are not well understood. In this study, to identify the ncRNAs induced by oxaliplatin, we profile the expression of ncRNAs in oxaliplatin-resistant HCT116 CRC cells (HCT116oxR) and parental HCT116 cells using next-generation sequencing technology.
Project description:Oxaliplatin resistance was induced in 2 colorectal cancer cell lines (LoVo-92, wt-p53 and LoVo-Li, functionally inactive p53) and one ovarian cancer cell line (A2780, wt-p53). Resistance was induced by weekly exposure to oxaliplatin for 4 hrs or 72 hrs with increasing concentrations for a period of 7 months Genomic DNA of oxaliplatin and cisplatin resistant colorectal cancer and ovarian cancer cell lines as well as the parental cell lines were labeled and subsequently hybridized against pooled reference DNA of healthy volunteers of the opposite gender using across array hybridization. Extracted raw-data were normalised and smoothend using the R-script NOWAVE resulting in normalised log2 ratio profiles of resistant cell line versus parental cell line and parental cell line versus reference DNA.
Project description:Oxaliplatin as a first-line drug frequently causes the chemo-resistance on colorectal cancer (CRC). N6-methyladenosine (m6A) methylation has been largely acknowledged in multiple biological functions. However, the molecular mechanisms underlying the m6A methylation in modulating anticancer drug resistance in CRC are still obscure. In present study, RIP-seq was conducted to investigate the occupancy of N6-methyladenosine RNA binding protein 3 (YTHDF3) served as “readers” that can recognize m6A modification site in HCT116 cells with oxaliplatin resistance (HCT116R). Then, YTHDF3 was knockdown by siRNA in HCT116 cells with oxaliplatin resistance, and RIP-seq was further conducted to investigate m6A methylation of HCT116, HCT116R and HCT116R cells with YTHDF3 knockdown.
Project description:Purpose: Irinotecan (SN38) and oxaliplatin are chemotherapeutic agents used in the treatment of colorectal cancer. However, the frequent development of resistance to these drugs represents a considerable challenge in the clinic. Alus as retrotransposons comprise 11% of the human genome. Genomic toxicity induced by carcinogens or drugs can reactivate Alus by altering DNA methylation. Whether or not reactivation of Alus occurs in SN38 and oxaliplatin resistance remains unknown. Methods: We applied reduced representation bisulfite sequencing (RRBS) to investigate the DNA methylome in SN38- or oxaliplatin-resistant colorectal cancer cell line models. Moreover, we extended the RRBS analysis to tumor tissue from 14 patients with colorectal cancer who either did or did not benefit from capecitabine + oxaliplatin treatment. For the clinical samples, we applied a concept of DNA methylation entropy to estimate the diversity of DNA methylation states of the identified resistance phenotype-associated methylation loci observed in the cell line models. Results: We identified different loci being characteristic for the different resistant cell lines. Interestingly, 53% of the identified loci were Alu sequences -- especially the Alu Y subfamily. Furthermore, we identified an enrichment of Alu Y sequences that likely results from increased integration of new copies of Alu Y sequence in the drug-resistant cell lines. In the clinical samples, SOX1 and other SOX gene family members were shown to display variable DNA methylation states in their gene regions. The Alu Y sequences showed remarkable variation in DNA methylation states across the clinical samples. Our findings imply a crucial role of Alu Y in colorectal cancer drug resistance. Our study underscores the complexity of colorectal cancer aggravated by mobility of Alu elements and stresses the importance of personalized strategies, using a systematic and dynamic view, for effective cancer therapy. Investigation of the representive methylome of well-established SN38 and Oxaliplatin resistant cell line models and 14 clinical colorectal metastatic samples that have developed resistance to XELOX to review the epigenetic mechnism of the drug resistance.
Project description:In the present study, we investigated miRNA expression changes caused by aquired chemoresistance to 5-FU or Oxa. 40 and 14 miRNAs were detected as differentially expressed in 5-fluouracil- and oxaliplatin-resistant colorectal HCT116 sublines, respectively. Differentially expressed miRNAs determined in the present study could be applied for further development of diagnostic and therapeutic applications for colorectal cancer carcinoma resistant to 5-FU or Oxa.
Project description:The human colorectal cancer cell line HCT116 was cultured in media alone, with gemcitabine (GEM), oxaliplatin (OXP), docetaxel (DOC), Artesunate (ARS), Lenalidomide, camptothecin (CAM) or interferon-γ for 4 hours. RNA was then isolated from from the cells by Trizol. Total RNA was labelled and hybridised to Illumina Human HT-12v3 arrays.
