YTHDF3 improves translation initiation of mRNAs with N6-methyladenosine methylation at 5’ untranslated region by facilitating eIF2AK2 recruitment in oxaliplatin-resistant colorectal cancer - RNA-seq cell line comparison
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ABSTRACT: 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: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: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 CRC tissues from three patients at different disease stages (CapeOx combined chemotherapy sensitivity and resistance).
Project description:HCT116 parental, HCT116 5-FU resistant and HCT116 oxaliplatin resistant cells have been transiently treated with with their respective drug (5-FU or oxaliplatin) for 0, 6 12 or 24h in 3 independent experiments.
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:The excessive and continuous activated Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway leads to the proliferation and migration of malignant cells resulting in the occurrence and development of almost all of cancers. The defined gene sets specifically activated by different STAT proteins are relied on their genomic accessibility by the interplay of certain STAT proteins with other potential cofactors. However, we have no clue about the status of human activated STAT dimers in the nucleus, as well as the intercrossing modules of synergic, supplementary or competitive relationship among each other in colorectal cancer. In current study, chromatin immunoprecipitation sequencing (ChIP-seq) was conducted to explore the genome-scale binding signatures of STAT1, STAT2, STAT3, STAT5A/B and STAT6 in human HCT-116 CRC cells. Moreover, STAT3 binding on genomic DNA was also investigated in HCT116 cells with NR5A2 knockdown.
Project description:Patients with advanced colorectal cancer (CRC) are commonly treated with systemic combination therapy but suffer eventually from drug resistance. MicroRNAs (miRNAs) are suggested to play a role in treatment resistance of CRC. We studied whether restoring downregulated miR-195-5p and 497-5p sensitize CRC cells to currently used chemotherapeutics 5-fluorouracil, oxaliplatin and irinotecan. Sensitivity to 5-FU, oxaliplatin and irinotecan before and after transfection with miR-195-5p and miR-497-5p mimics was analyzed in CRC cell lines HCT116, RKO, DLD-1 and SW480. Mass spectrometry based proteomic analysis of transfected and wild-type cells was used to identify targets involved in sensitivity to chemotherapy. Proteomic analysis revealed 181 proteins with significantly altered expression after transfection with miR-195-5p mimic in HCT116 and RKO, including 118 downregulated and 63 upregulated proteins. After transfection with miR-497-5p mimic, 130 proteins were significantly downregulated and 102 were upregulated in HCT116 and RKO (P<0.05 and FC<-3 or FC>3). CHUK and LUZP1 were coinciding downregulated proteins in sensitized CRC cells after transfection with either mimic. Resistance mechanisms of these two proteins may be related to nuclear factor kappa-B signaling and G1 cell cycle arrest, respectively. Restoring miR-195-5p and miR-497-5p expression enhanced sensitivity to chemotherapy, mainly oxaliplatin, in CRC cells and could be a promising treatment strategy for patients with mCRC. Proteomics revealed potential targets of these miRNAs involved in sensitivity to chemotherapy.
Project description:Almost half of the patients with advanced colorectal cancer (CRC) are resistant to oxaliplatin based therapy, the first line treatment for CRC. Therefore, predicting and understanding oxaliplatin resistance is important to improve CRC patient survival. Investigated here is the use of proteomic folding stability measurements to differentiate oxaliplatin resistant and sensitive CRCs using patient-derived CRC cell lines and patient-derived xenografts (PDXs). Three protein stability profiling techniques (including the Stability of Proteins from Rates of Oxidation (SPROX), the Thermal Protein Profiling (TPP), and Limited Proteolysis (LiP) approaches) were employed to identify differentially stabilized proteins in 6 patient-derived CRC cell lines with different oxaliplatin sensitivities and 8 CRC PDXs derived from 2 of the patient derived cell lines with different oxaliplatin sensitivity. A total of 23 proteins were found in at least 2 techniques to be differentially stabilized in both the cell line and PDX studies of oxaliplatin resistance. These 23 differentially stabilized proteins included 9 proteins that have been previously connected to cancer chemoresistance. Over-representation analysis (ORA) of all the differentially stabilized proteins identified here, revealed novel pathways related to oxaliplatin resistance. Compared to conventional protein expression level analyses, which were also performed on the cell lines and PDXs, the stability profiling techniques identified novel proteins and pathways and provided new insight on the molecular basis of oxaliplatin resistance. Our results suggest that protein stability profiling techniques are complementary to expression level analyses for identifying biomarkers and understanding molecular mechanisms associated with oxaliplatin chemoresistance in CRC and disease phenotypes in general.
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: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:We identified that miR-1 is silenced in association with CpG island hypermethylation in a colorectal cancer (CRC) cell line, HCT116. To determine whether miR-1 serves as a tumor suppressor in CRC, we transfected CRC cell lines with a miR-1 precursor molecule or a negative control, and carried then out a series of MTT assays. Forty-eight hours after transfection, we observed that ectopic expression of miR-1 moderately suppressed growth in all three cell lines. To further clarify the effect of the miRNA, we next performed gene expression microarray analysis in HCT116 cells transfected with a miR-1 precursor molecule or a negative control. We found that 2769 probe sets were downregulated (> 1.5-fold) by ectopic miR-1 expression, and gene ontology analysis revealed that “extracellular regions”, “membrane” and “response to wound healing” genes were significantly enriched among the downregulated genes. HCT116 cells were transfected with a Pre-miR-1 miRNA Precursor Molecule (Ambion) or Pre-miR miRNA Molecules Negative Control #1 (Ambion). Forty-eight hours after transfection, total RNA extraction were carried out, and gene expression signatures were analyzed.