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1.
Drug Resist Updat ; 71: 100993, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37639774

ABSTRACT

AIMS: Drivers of the drug tolerant proliferative persister (DTPP) state have not been well investigated. Histone H3 lysine-4 trimethylation (H3K4me3), an active histone mark, might enable slow cycling drug tolerant persisters (DTP) to regain proliferative capacity. This study aimed to determine H3K4me3 transcriptionally active sites identifying a key regulator of DTPPs. METHODS: Deploying a model of adaptive cancer drug tolerance, H3K4me3 ChIP-Seq data of DTPPs guided identification of top transcription factor binding motifs. These suggested involvement of O-linked N-acetylglucosamine transferase (OGT), which was confirmed by metabolomics analysis and biochemical assays. OGT impact on DTPPs and adaptive resistance was explored in vitro and in vivo. RESULTS: H3K4me3 remodeling was widespread in CPG island regions and DNA binding motifs associated with O-GlcNAc marked chromatin. Accordingly, we observed an upregulation of OGT, O-GlcNAc and its binding partner TET1 in chronically treated cancer cells. Inhibition of OGT led to loss of H3K4me3 and downregulation of genes contributing to drug resistance. Genetic ablation of OGT prevented acquired drug resistance in in vivo models. Upstream of OGT, we identified AMPK as an actionable target. AMPK activation by acetyl salicylic acid downregulated OGT with similar effects on delaying acquired resistance. CONCLUSION: Our findings uncover a fundamental mechanism of adaptive drug resistance that governs cancer cell reprogramming towards acquired drug resistance, a process that can be exploited to improve response duration and patient outcomes.


Subject(s)
AMP-Activated Protein Kinases , Histones , Humans , Histones/genetics , Down-Regulation , Mixed Function Oxygenases , Proto-Oncogene Proteins
2.
Cancer Res ; 82(9): 1736-1752, 2022 05 03.
Article in English | MEDLINE | ID: mdl-35502547

ABSTRACT

Aneuploidy is a hallmark of cancer with tissue-specific prevalence patterns that suggest it plays a driving role in cancer initiation and progression. However, the contribution of aneuploidy to tumorigenesis depends on both cellular and genomic contexts. Whole-genome duplication (WGD) is a common macroevolutionary event that occurs in more than 30% of human tumors early in tumorigenesis. Although tumors that have undergone WGD are reported to be more permissive to aneuploidy, it remains unknown whether WGD also affects aneuploidy prevalence patterns. Here we analyzed clinical tumor samples from 5,586 WGD- tumors and 3,435 WGD+ tumors across 22 tumor types and found distinct patterns of aneuploidy in WGD- and WGD+ tumors. WGD+ tumors were characterized by more promiscuous aneuploidy patterns, in line with increased aneuploidy tolerance. Moreover, the genetic interactions between chromosome arms differed between WGD- and WGD+ tumors, giving rise to distinct cooccurrence and mutual exclusivity aneuploidy patterns. The proportion of whole-chromosome aneuploidy compared with arm-level aneuploidy was significantly higher in WGD+ tumors, indicating distinct dominant mechanisms for aneuploidy formation. Human cancer cell lines successfully reproduced these WGD/aneuploidy interactions, confirming the relevance of studying this phenomenon in culture. Finally, induction of WGD and assessment of aneuploidy in isogenic WGD-/WGD+ human colon cancer cell lines under standard or selective conditions validated key findings from the clinical tumor analysis, supporting a causal link between WGD and altered aneuploidy landscapes. We conclude that WGD shapes the aneuploidy landscape of human tumors and propose that this interaction contributes to tumor evolution. SIGNIFICANCE: These findings suggest that the interactions between whole-genome duplication and aneuploidy are important for tumor evolution, highlighting the need to consider genome status in the analysis and modeling of cancer aneuploidy.


Subject(s)
Gene Duplication , Neoplasms , Aneuploidy , Carcinogenesis/genetics , Genome , Humans , Neoplasms/genetics
3.
Cell Cycle ; 19(24): 3508-3520, 2020 12.
Article in English | MEDLINE | ID: mdl-33305692

ABSTRACT

Aneuploidy is the condition of having an imbalanced karyotype, which is associated with tumor initiation, evolution, and acquisition of drug-resistant features, possibly by generating heterogeneous populations of cells with distinct genotypes and phenotypes. Multicellular eukaryotes have therefore evolved a range of extrinsic and cell-autonomous mechanisms for restraining proliferation of aneuploid cells, including activation of the tumor suppressor protein p53. However, accumulating evidence indicates that a subset of aneuploid cells can escape p53-mediated growth restriction and continue proliferating in vitro. Here we show that such aneuploid cell lines display a robust modal karyotype and low frequency of chromosomal aberrations despite ongoing chromosome instability. Indeed, while these aneuploid cells are able to survive for extended periods in vitro, their chromosomally unstable progeny remain subject to p53-induced senescence and growth restriction, leading to subsequent elimination from the aneuploid pool. This mechanism helps maintain low levels of heterogeneity in aneuploid populations and may prevent detrimental evolutionary processes such as cancer progression and development of drug resistance.


Subject(s)
Aneuploidy , Cellular Senescence/genetics , Epithelial Cells/metabolism , Retinal Pigment Epithelium/cytology , Tumor Suppressor Protein p53/metabolism , Cell Cycle Checkpoints/genetics , Cell Proliferation/genetics , Cell Transformation, Neoplastic/genetics , Cell Transformation, Neoplastic/metabolism , Chromosomal Instability/genetics , Chromosome Segregation/genetics , Gene Knockdown Techniques , HEK293 Cells , Humans , Karyotype , Tumor Suppressor Protein p53/genetics
4.
Cell Death Differ ; 27(2): 742-757, 2020 02.
Article in English | MEDLINE | ID: mdl-31296963

ABSTRACT

Gastrointestinal epithelial cells provide a selective barrier that segregates the host immune system from luminal microorganisms, thereby contributing directly to the regulation of homeostasis. We have shown that from early embryonic development Bcl-G, a Bcl-2 protein family member with unknown function, was highly expressed in gastrointestinal epithelial cells. While Bcl-G was dispensable for normal growth and development in mice, the loss of Bcl-G resulted in accelerated progression of colitis-associated cancer. A label-free quantitative proteomics approach revealed that Bcl-G may contribute to the stability of a mucin network, which when disrupted, is linked to colon tumorigenesis. Consistent with this, we observed a significant reduction in Bcl-G expression in human colorectal tumors. Our study identifies an unappreciated role for Bcl-G in colon cancer.


Subject(s)
Colorectal Neoplasms/metabolism , Inflammation/metabolism , Proto-Oncogene Proteins c-bcl-2/metabolism , Animals , Colitis/metabolism , Colitis/pathology , Colorectal Neoplasms/pathology , Humans , Inflammation/pathology , Mice , Mice, Knockout , Proto-Oncogene Proteins c-bcl-2/deficiency , Proto-Oncogene Proteins c-bcl-2/genetics
5.
Stem Cell Reports ; 8(6): 1675-1688, 2017 06 06.
Article in English | MEDLINE | ID: mdl-28591650

ABSTRACT

Pluripotent stem cells have been proposed as an unlimited source of pancreatic ß cells for studying and treating diabetes. However, the long, multi-step differentiation protocols used to generate functional ß cells inevitably exhibit considerable variability, particularly when applied to pluripotent cells from diverse genetic backgrounds. We have developed culture conditions that support long-term self-renewal of human multipotent pancreatic progenitors, which are developmentally more proximal to the specialized cells of the adult pancreas. These cultured pancreatic progenitor (cPP) cells express key pancreatic transcription factors, including PDX1 and SOX9, and exhibit transcriptomes closely related to their in vivo counterparts. Upon exposure to differentiation cues, cPP cells give rise to pancreatic endocrine, acinar, and ductal lineages, indicating multilineage potency. Furthermore, cPP cells generate insulin+ ß-like cells in vitro and in vivo, suggesting that they offer a convenient alternative to pluripotent cells as a source of adult cell types for modeling pancreatic development and diabetes.


Subject(s)
Cell Self Renewal/physiology , Pluripotent Stem Cells/cytology , Stem Cells/cytology , Animals , Cell Differentiation/drug effects , Cell Line , Down-Regulation , Feeder Cells/cytology , Feeder Cells/metabolism , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Humans , Insulin/pharmacology , Insulin-Secreting Cells/cytology , Insulin-Secreting Cells/metabolism , Kidney/metabolism , Kidney/pathology , Mice , Mice, Inbred NOD , Mice, SCID , Pancreas/cytology , Pluripotent Stem Cells/metabolism , SOX9 Transcription Factor/metabolism , Stem Cells/metabolism , Trans-Activators/metabolism , Transplantation, Heterologous
6.
Cell Div ; 10: 3, 2015.
Article in English | MEDLINE | ID: mdl-26015801

ABSTRACT

Genomic instability (GIN) is a hallmark of cancer cells that facilitates the acquisition of mutations conferring aggressive or drug-resistant phenotypes during cancer evolution. Chromosomal instability (CIN) is a form of GIN that involves frequent cytogenetic changes leading to changes in chromosome copy number (aneuploidy). While both CIN and aneuploidy are common characteristics of cancer cells, their roles in tumor initiation and progression are unclear. On the one hand, CIN and aneuploidy are known to provide genetic variation to allow cells to adapt in changing environments such as nutrient fluctuations and hypoxia. Patients with constitutive aneuploidies are more susceptible to certain types of cancers, suggesting that changes in chromosome copy number could positively contribute to cancer evolution. On the other hand, chromosomal imbalances have been observed to have detrimental effects on cellular fitness and might trigger cell cycle arrest or apoptosis. Furthermore, mouse models for CIN have led to conflicting results. Taken together these findings suggest that the relationship between CIN, aneuploidy and cancer is more complex than what was previously anticipated. Here we review what is known about this complex ménage à trois, discuss recent evidence suggesting that aneuploidy, CIN and GIN together promote a vicious cycle of genome chaos. Lastly, we propose a working hypothesis to reconcile the conflicting observations regarding the role of aneuploidy and CIN in tumorigenesis.

7.
J Cell Biol ; 186(3): 355-62, 2009 Aug 10.
Article in English | MEDLINE | ID: mdl-19651893

ABSTRACT

Proteins of the Bcl-2 family are critical regulators of apoptosis, but how its BH3-only members activate the essential effectors Bax and Bak remains controversial. The indirect activation model suggests that they simply must neutralize all of the prosurvival Bcl-2 family members, whereas the direct activation model proposes that Bim and Bid must activate Bax and Bak directly. As numerous in vitro studies have not resolved this issue, we have investigated Bim's activity in vivo by a genetic approach. Because the BH3 domain determines binding specificity for Bcl-2 relatives, we generated mice having the Bim BH3 domain replaced by that of Bad, Noxa, or Puma. The mutants bound the expected subsets of prosurvival relatives but lost interaction with Bax. Analysis of the mice showed that Bim's proapoptotic activity is not solely caused by its ability to engage its prosurvival relatives or solely to its binding to Bax. Thus, initiation of apoptosis in vivo appears to require features of both models.


Subject(s)
Apoptosis Regulatory Proteins/metabolism , Membrane Proteins/metabolism , Proto-Oncogene Proteins c-bcl-2/antagonists & inhibitors , Proto-Oncogene Proteins/metabolism , Animals , Apoptosis , Apoptosis Regulatory Proteins/deficiency , Apoptosis Regulatory Proteins/genetics , Bcl-2-Like Protein 11 , Membrane Proteins/deficiency , Membrane Proteins/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Mutation , Proto-Oncogene Proteins/deficiency , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism
8.
Mol Cells ; 27(5): 577-82, 2009 May 31.
Article in English | MEDLINE | ID: mdl-19466607

ABSTRACT

The development of a high-throughput functional genomic screening provides a novel and expeditious approach in identifying critical genes involved in specific biological processes. Here we describe a cell-based cDNA screening system to identify the transcription activators of BiP, an endoplasmic reticulum (ER) chaperone protein. BiP promoter contains the ER stress element which is commonly present in the genes involved in unfolded protein response (UPR) that regulates protein secretion in cells. Therefore, the positive regulators of BiP may also be utilized to improve the recombinant protein production through modulation of UPR. Four BiP activators, including human UDP-glucose:glycoprotein glucosyltransferase 1 (HUGT1), are identified by the cDNA screening. Overexpression of HUGT1 leads to a significant increase in the production of recombinant erythropoietin, interferon gamma, and monoclonal antibody in HEK293 cells. Our results demonstrate that the cDNA screening for BiP activators may be effective to identify the novel BiP regulators and HUGT1 may serve as an ideal target gene for improving the recombinant protein production in mammalian cells.


Subject(s)
Antibodies, Monoclonal/metabolism , Erythropoietin/metabolism , Heat-Shock Proteins/genetics , Interferon-gamma/metabolism , Monosaccharide Transport Proteins/genetics , Recombinant Proteins/metabolism , Antibodies, Monoclonal/genetics , Biotechnology , Cell Line , Endoplasmic Reticulum , Endoplasmic Reticulum Chaperone BiP , Erythropoietin/genetics , Gene Library , Gene Targeting/methods , Gene Targeting/trends , Genetic Engineering/trends , Heat-Shock Proteins/metabolism , Humans , Interferon-gamma/genetics , Monosaccharide Transport Proteins/metabolism , Protein Folding , Recombinant Proteins/genetics , Transcriptional Activation
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