Pancreatic ductal adenocarcinoma (PDA) is a major cause of cancer-related death with limited therapeutic options available. This highlights the need for improved understanding of the biology of PDA ...progression, a highly complex and dynamic process featuring changes in cancer cells and stromal cells. A comprehensive characterization of PDA cancer cell and stromal cell heterogeneity during disease progression is lacking. In this study, we aimed to profile cell populations and understand their phenotypic changes during PDA progression. To that end, we employed single-cell RNA sequencing technology to agnostically profile cell heterogeneity during different stages of PDA progression in genetically engineered mouse models. Our data indicate that an epithelial-to-mesenchymal transition of cancer cells accompanies tumor progression in addition to distinct populations of macrophages with increasing inflammatory features. We also noted the existence of three distinct molecular subtypes of fibroblasts in the normal mouse pancreas, which ultimately gave rise to two distinct populations of fibroblasts in advanced PDA, supporting recent reports on intratumoral fibroblast heterogeneity. Our data also suggest that cancer cells and fibroblasts may be dynamically regulated by epigenetic mechanisms. This study systematically describes the landscape of cellular heterogeneity during the progression of PDA and has the potential to act as a resource in the development of therapeutic strategies against specific cell populations of the disease.
Cytokine-induced activation of the IκB kinases (IKK) IKK-α and IKK-β is a key step involved in the activation of the NF-κB pathway. Gene-disruption studies of the murine IKK genes have shown that ...IKK-β, but not IKK-α, is critical for cytokine-induced IκB degradation. Nevertheless, mouse embryo fibroblasts deficient in IKK-α are defective in the induction of NF-κB-dependent transcription. These observations raised the question of whether IKK-α might regulate a previously undescribed step to activate the NF-κB pathway that is independent of its previously described cytoplasmic role in the phosphorylation of IκBα. Here we show that IKK-α functions in the nucleus to activate the expression of NF-κB-responsive genes after stimulation with cytokines. IKK-α interacts with CREB-binding protein and in conjunction with Rel A is recruited to NF-κB-responsive promoters and mediates the cytokine-induced phosphorylation and subsequent acetylation of specific residues in histone H3. These results define a new nuclear role of IKK-α in modifying histone function that is critical for the activation of NF-κB-directed gene expression.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The β-catenin and APC genes are key components of the Wnt signaling pathway. Mutation of these genes results in increased levels of the β-catenin
protein, which is associated with enhanced cellular ...proliferation and the development of both colon polyps and colon cancer.
Recently, a technique known as RNA interference has been successfully adapted to mammalian cells so that it is now possible
to specifically decrease the expression of cellular genes after transfection of annealed small interfering 21-mer RNAs. In
the current study, we used small interfering RNA (siRNA) directed against β-catenin to determine the effects of decreasing
the high constitutive levels of this protein in colon cancer cell lines with mutations in either β-catenin or APC. Our studies
demonstrate that siRNA directed against β-catenin markedly decreased β-catenin-dependent gene expression and inhibited cellular
proliferation as reflected in the reduced growth of these colon cancer cells both in soft agar and in nude mice. These results
indicate that siRNA can target specific factors whose expression is altered in malignancy and may have the potential as a
therapeutic modality to treat human cancer.
Background: We studied the effect of race and ethnicity on disease characteristics and survival in gastrointestinal neuroendocrine tumors. Methods: The Surveillance, Epidemiology, and End Results ...database was used to select patients with non-pancreatic gastrointestinal neuroendocrine tumors diagnosed between 2004 and 2015. Trends in survival were evaluated among three groups: Hispanic, non-Hispanic White, and non-Hispanic Black. Kaplan–Meier and Cox regression methods were performed to calculate overall survival and cause-specific survival after adjusting for patient and tumor characteristics. Results: A total of 26,399 patients were included in the study: 65.1% were non-Hispanic White, 19.9% were non-Hispanic Black, and 15% were Hispanic. Non-Hispanic White patients were more likely to be male (50.0%, p < 0.001), older than 60 years (48.0%, p < 0.001), and present with metastatic disease (17.7%, p < 0.001). Non-Hispanic White patients had small intestine neuroendocrine tumors, while Hispanic and non-Hispanic Black patients had rectum neuroendocrine tumors as the most common primary site. Hispanic patients had better overall survival, while non-Hispanic Black patients had better cause-specific survival versus non-Hispanic White patients. This finding was confirmed on multivariable analysis where Hispanic patients had improved overall survival compared to non-Hispanic White patients (Hazard ratio (HR): 0.89 (0.81–0.97)), whereas non-Hispanic Black patients had better cause-specific survival compared to non-Hispanic White patients (HR: 0.89 (0.80–0.98)). Conclusions: Race/ethnicity is an independent prognostic factor in patients with gastrointestinal neuroendocrine tumors.
Purpose: The purpose of this study was to profile gene expression changes in colorectal tumors to identify new targets and strategies
for the management of this disease.
Experimental Design: cDNA ...microarray analysis was used to detect differences in gene expression between normal tissue and colon tumors and polyps
isolated from 20 patients. To identify genes that are important in regulating the growth properties of colorectal cancer,
RNA interference (RNAi) was used to disrupt expression of several of the overexpressed genes in a colon tumor cell line, HCT116,
which showed similar patterns of gene expression as many of the patient tumors.
Results: Expression changes of ≥2-fold in approximately one-third of the patients were consistently observed for 2632 of a total of
9592 genes (574 up-regulated genes and 2058 down-regulated genes). Subsequent analysis of 13 genes by quantitative real-time
PCR confirmed the reliability of this analysis. RNAi-mediated disruption of the expression of one of these genes, survivin,
a potent inhibitor of apoptosis, severely reduced tumor growth both in vitro and in an in vivo xenograft model.
Conclusions: The combined use of microarray analysis and RNAi provides an excellent system to define the role of specific genes that are
up-regulated in cancer lead to the increased in vitro and in vivo growth of colon tumors.
In preclinical tumor models, inhibition of nuclear factor-κB (NF-κB) has been associated with increased sensitivity to chemotherapeutic
agents such as irinotecan (CPT-11). This is based on the fact ...that a variety of chemotherapy agents such as CPT-11 activate
NF-κB to result in the expression of genes such as c-IAP1 and c-IAP2 that might be responsible for the inhibition of chemotherapy-induced apoptosis. In this study, RNA interference small interfering
RNA (siRNA) was used to down-regulate the NF-κB p65 subunit in the HCT116 colon cancer cell line, and its role, in the presence
and absence of CPT-11, was assessed on cell growth and apoptosis. Reduction of endogenous p65 by siRNA treatment significantly
impaired CPT-11-mediated NF-κB activation, enhanced apoptosis, and reduced colony formation in soft agar. Furthermore, the
in vivo administration of p65 siRNA reduced HCT116 tumor formation in xenograft models in the presence but not the absence of CPT-11
administration. These data indicate that the administration of siRNA directed against the p65 subunit of NF-κB can effectively
enhance in vitro and in vivo sensitivity to chemotherapeutic agents.
The catalytic subunits of IκB kinase (IKK) complex, IKKα and IKKβ, are involved in activation of NF-κB and in mediating a variety of other biological functions. Though these proteins have a ...high-sequence homology, IKKα exhibits different functional characteristics as compared with IKKβ. Earlier, we have shown that cyclin D1 is overexpressed and predominantly localized in the nucleus of IKKα(-/-) cells, indicating that IKKα regulates turnover and subcellular distribution of cyclin D1, which is mediated by IKKα-induced phosphorylation of cyclin D1. Because cyclin D nuclear localization is implicated in tumor development, we examined whether the absence of IKKα leads to tumor development as well. In the current study, we show that IKKα plays a critical role in tumorigenesis. Though IKKα(-/-) MEF cells show a slower anchorage-dependent growth, they are clonogenic in soft agar. These cells are tumorigenic in nude mice. Microarray analysis of IKKα(-/-) cells indicates a differential expression of genes involved in proliferation and apoptosis. Furthermore, analysis of microarray data of human lung cancer cell lines revealed decreased IKKα RNA expression level as compared with cell lines derived from normal bronchial epithelium. These results suggest that IKKα may function as a tumor suppressor gene. Absence of IKKα may induce tumorigenicity by nuclear localization of cyclin D1 and modulating the expression of genes involved in neoplastic transformation.
The I kappa B kinase (IKK) complex, which is composed of the two kinases IKK alpha and IKK beta and the regulatory subunit IKK gamma/nuclear factor-kappa B (NF-kappa B) essential modulator (NEMO), is ...important in the cytokine-induced activation of the NF-kappa B pathway. In addition to modulation of IKK activity, the NF-kappa B pathway is also regulated by other processes, including the nucleocytoplasmic shuttling of various components of this pathway and the post-translational modification of factors bound to NF-kappa B-dependent promoters. In this study, we explored the role of the nucleocytoplasmic shuttling of components of the IKK complex in the regulation of the NF-kappa B pathway. IKK gamma/NEMO was demonstrated to shuttle between the cytoplasm and the nucleus and to interact with the nuclear coactivator cAMP-responsive element-binding protein-binding protein (CBP). Using both in vitro and in vivo analysis, we demonstrated that IKK gamma/NEMO competed with p65 and IKK alpha for binding to the N terminus of CBP, inhibiting CBP-dependent transcriptional activation. These results indicate that, in addition to the key role of IKK gamma/NEMO in regulating cytokine-induced IKK activity, its ability to shuttle between the cytoplasm and the nucleus and to bind to CBP can lead to transcriptional repression of the NF-kappa B pathway.
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