ABSTRACT: 5-Fluorouracil (5-FU) is one of the most common drugs used in chemotherapy because of its efficacy and stability. However, 5-FU has been known to work on only 10~15% of colon cancer patients. Therefore, the study of 5-FU sensitivity study is necessary to increase the survival of colon cancer patients. p53 is one of the factors that effect on drug sensitivity. Main function of p53 has been focused on transcription activity in cell death. Numerous drug related studies show that expression of wild-type p53 increases drug sensitivity in various cancer types through inducing apoptotic signaling pathways. Currently, it has been reported that p53 has both transcriptional and non-transcriptional activities in apoptosis. However, most studies about p53 non-transcriptional activities in apoptosis are mainly focused on p53 induced mitochondrial outer membrane permeabilization, triggering the release of pro-apoptotic factors. The chromatin structure and organization have strongly attracted because of their impacts in cellular phenotypes. Recent studies have been shown that changes in chromatin accessibility affect cell phenotypes for external stimuli. Since p53 plays an important role in drug sensitivity and 5-FU is an external stimulus for cancer cells, we hypothesized that p53 may effect on 5-FU sensitivity through different regulation of chromatin accessible regions between TP53-WT and TP53-KO cells. To determine the effect of p53 on chromatin accessibility modification associated with 5-FU sensitivity, ATAC-seq and RNA-seq were performed under 5-FU treatment on TP53-WT as drug sensitive and TP53-KO as drug resistant HCT116 cells. In this study, we found that 5-FU induces chromatin accessibility in both TP53-WT and TP53-KO cells. Moreover, our results show that 5-FU induced chromatin accessibility increases expression of apoptotic genes in TP53-WT HCT116 cells through p53 non-transcriptional activity in nucleus.
Project description:5-Fluorouracil (5-FU) is one of the most common drugs used in chemotherapy because of its efficacy and stability. However, 5-FU has been known to work on only 10~15% of colon cancer patients. Therefore, the study of 5-FU sensitivity study is necessary to increase the survival of colon cancer patients. p53 is one of the factors that effect on drug sensitivity. Main function of p53 has been focused on transcription activity in cell death. Numerous drug related studies show that expression of wild-type p53 increases drug sensitivity in various cancer types through inducing apoptotic signaling pathways. Currently, it has been reported that p53 has both transcriptional and non-transcriptional activities in apoptosis. However, most studies about p53 non-transcriptional activities in apoptosis are mainly focused on p53 induced mitochondrial outer membrane permeabilization, triggering the release of pro-apoptotic factors. The chromatin structure and organization have strongly attracted because of their impacts in cellular phenotypes. Recent studies have been shown that changes in chromatin accessibility affect cell phenotypes for external stimuli. Since p53 plays an important role in drug sensitivity and 5-FU is an external stimulus for cancer cells, we hypothesized that p53 may effect on 5-FU sensitivity through different regulation of chromatin accessible regions between TP53-WT and TP53-KO cells. To determine the effect of p53 on chromatin accessibility modification associated with 5-FU sensitivity, ATAC-seq and RNA-seq were performed under 5-FU treatment on TP53-WT as drug sensitive and TP53-KO as drug resistant HCT116 cells. In this study, we found that 5-FU induces chromatin accessibility in both TP53-WT and TP53-KO cells. Moreover, our results show that 5-FU induced chromatin accessibility increases expression of apoptotic genes in TP53-WT HCT116 cells through p53 non-transcriptional activity in nucleus.
Project description:Purpose: Next-generation sequencing (NGS) has revolutionized systems-based analysis of cellular pathways. The goals of this study are to compare TP53-WT and TP53-KO HCT116 cells transcriptome profiling (RNA-seq) under 5-FU treatment condition and to evaluate the correlation between transcriptome profileing and chromatin accessibility under 5-FU treatment. Methods: HCT116 cell profiles of TP53-WT and TP53- KO were generated by deep sequencing, in duplicates, using Illumina GAIIx. The sequence reads that passed quality filters were analyzed at the transcript isoform levels: Burrows–Wheeler Aligner (BWA) followed by ANOVA (ANOVA). Conclusions: Our study represents the detailed analysis of TP53-WT and TP53-KO HCT116 cell transcriptomes under 5-FU treatment with different timepoint, with biologic replicates, generated by RNA-seq technology. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. Our results show that RNA-seq offers a comprehensive and more accurate quantitative and qualitative evaluation of mRNA content within a TP53-WT and TP53-KO cells with and without 5-FU treatment in different timepoint. We conclude that NGS based transcriptome characterization would expedite genetic network analyses and permit the dissection of complex biologic functions.
Project description:Deletion (Del) of 17p involving the TP53 tumor suppressor remains an adverse prognostic factor in multiple myeloma, and more effective targeted therapies are needed for these patients. Genomic studies revealed that del17p was associated with reduced copy number and mRNA expression of RNA polymerase II subunit alpha (POLR2A), which is located near TP53. We therefore studied HDP-101, an anti-B-cell maturation antigen (BCMA) antibody drug conjugate (ADC) with the POLR2A poison α-amanitin, which showed potent anti-proliferative and pro-apoptotic activity against cell lines and primary samples. POLR2A knockdown (KD) in both TP53 wild-type (WT) and knockout (KO) cells, with the latter being a model of del17p, enhanced sensitivity to HDP-101 compared to POLR2A WT cells. Gene expression profiling and proteomic studies showed evidence for activation of endoplasmic reticulum stress and the unfolded protein response, as well as a reduction of anti-apoptotic proteins such as Myeloid cell leukemia (MCL)-1. Bortezomib enhanced the activity of HDP-101, as did a gamma-secretase inhibitor, and this ADC overcame resistance both due to microenvironmental factors and in acquired drug resistance models. Finally, HDP-101 was well tolerated in vivo, reduced disease burden with single, 2-4 mg/kg doses, and no evidence of relapse was seen out to 100 days, even in xenografts that modeled del17p through dual TP53 KO/POLR2A KD, which grew more aggressively without treatment. Together, the data validate the efficacy of a new BCMA ADC that is ready for clinical translation, and suggest that it could be equipotent, or perhaps even more effective against myeloma with del17p. We used microarray to investigate the global changes caused by HDP-101 across p53 Wt and p53 KO multiple myeloma cell lines
Project description:Since its discovery as a tumour suppressor some fifteen years ago, the transcription factor p53 has attracted paramount attention for its role as “the guardian of the genome”. TP53 mutations occur so frequently in cancer, regardless of patient age or tumour type, that they appear to be part of the life history of at least 50% of human tumours. In most tumours that retain wild-type p53, its function is inactivated due to deregulated HDM2, a protein which binds to p53 and which can inhibit the transcriptional activity of p53 and induce its degradation. RITA is a low-molecular-weight compound which addresses the second group of tumours retaining functionally reactive wt p53. It was found in a screening of the National Cancer Institute (NCI) library of low-molecular-weight compounds based on its ability to selectively kill wtp53-containing cells. RITA binds directly to p53 and diplaces its main destructor Mdm2, as well as inducing a shift in the conformation of p53. This is in contrast to the wtp53-reactivating compound Nutlin3a, which targets Mdm2, inhibiting its ability to degrade p53. Using microarray technology we have explored the effect of RITA on the transcriptome of isogenic cell-lines with knocked-out (KO) or intact (WT) TP53. While the effects on KO cells are below detection limit, the effects on WT cells are profound. The known p53 targets induced are predominately apoptotic, in contrast to the genes affected by Nutlin3a, which are exclusively growth-arrest genes. Keywords: Antitumor agent HCT116 parental and HCT116 p53-null (HCT116 TP53-/-) cells were subjected to treatment with 1uM RITA for 12h, or left untreated. The experiment was done in three independent biological replicates.
Project description:The tumor suppressor gene TP53 is mutated in approximately half of all human tumors. Of those, around 10% are nonsense mutations that produce truncated and inactive p53 protein. Induction of translational readthrough is a promising approach for rescuing full-length p53 and thereby eliminate tumor cells with nonsense mutant TP53. To find novel nonsense mutant TP53 readthrough-inducing compounds with a tolerable toxicity profile, we performed an in silico screening of data at the National Cancer Institute database and identified 5-Fluorouracil (5-FU). We show here that 5-FU induces full-length p53 in human tumor cells carrying R213X nonsense mutant TP53 and that this activity is mediated by its metabolite 5-Fluorouridine (FUr). Ribo-seq analysis validated induction of translational readthrough by FUr. We also show that FUr is incorporated into RNA where it potentially allows base pairing of Arg tRNA at the R213X UGA premature termination codon. Full-length p53 rescued by FUr is transcriptionally active and triggers p53-dependent cell death. Moreover, treatment with 5-FU or FUr restores full-length p53 expression in TP53 R213X mutant human tumor xenografts in vivo. Our results suggest that induction of readthrough by 5-FU/FUr could contribute to therapeutic efficacy in patients with TP53 nonsense mutant tumors.
Project description:The tumor suppressor gene TP53 is mutated in approximately half of all human tumors. Of those, around 10% are nonsense mutations that produce truncated and inactive p53 protein. Induction of translational readthrough is a promising approach for rescuing full-length p53 and thereby eliminate tumor cells with nonsense mutant TP53. To find novel nonsense mutant TP53 readthrough-inducing compounds with a tolerable toxicity profile, we performed an in silico screening of data at the National Cancer Institute database and identified 5-Fluorouracil (5-FU). We show here that 5-FU induces full-length p53 in human tumor cells carrying R213X nonsense mutant TP53 and that this activity is mediated by its metabolite 5-Fluorouridine (FUr). Ribo-seq analysis validated induction of translational readthrough by FUr. We also show that FUr is incorporated into RNA where it potentially allows base pairing of Arg tRNA at the R213X UGA premature termination codon. Full-length p53 rescued by FUr is transcriptionally active and triggers p53-dependent cell death. Moreover, treatment with 5-FU or FUr restores full-length p53 expression in TP53 R213X mutant human tumor xenografts in vivo. Our results suggest that induction of readthrough by 5-FU/FUr could contribute to therapeutic efficacy in patients with TP53 nonsense mutant tumors.
Project description:Since its discovery as a tumour suppressor some fifteen years ago, the transcription factor p53 has attracted paramount attention for its role as “the guardian of the genome”. TP53 mutations occur so frequently in cancer, regardless of patient age or tumour type, that they appear to be part of the life history of at least 50% of human tumours. In most tumours that retain wild-type p53, its function is inactivated due to deregulated HDM2, a protein which binds to p53 and which can inhibit the transcriptional activity of p53 and induce its degradation. RITA is a low-molecular-weight compound which addresses the second group of tumours retaining functionally reactive wt p53. It was found in a screening of the National Cancer Institute (NCI) library of low-molecular-weight compounds based on its ability to selectively kill wtp53-containing cells. RITA binds directly to p53 and diplaces its main destructor Mdm2, as well as inducing a shift in the conformation of p53. This is in contrast to the wtp53-reactivating compound Nutlin3a, which targets Mdm2, inhibiting its ability to degrade p53. Using microarray technology we have explored the effect of RITA on the transcriptome of isogenic cell-lines with knocked-out (KO) or intact (WT) TP53. While the effects on KO cells are below detection limit, the effects on WT cells are profound. The known p53 targets induced are predominately apoptotic, in contrast to the genes affected by Nutlin3a, which are exclusively growth-arrest genes. Keywords: Antitumor agent