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393 result(s) for "Cyclin-Dependent Kinase Inhibitor p15"
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Clinical outcome of treatment with a combined regimen of decitabine and aclacinomycin/cytarabine for patients with refractory acute myeloid leukemia
We conducted a clinical trial of low-dose decitabine plus aclacinomycin/cytarabine (AA) treatment (DAA) for 20 patients with refractory/relapsed de novo acute myeloid leukemia (AML) or AML transformed from myelodysplastic syndrome (MDS/AML) in order to examine its efficacy and tolerability. Additionally, P15 ink4b methylation status was analyzed (for 15 patients) pre- and post-DAA treatment, and in vitro drug sensitivity tests were performed for seven patients (AA or AA + decitabine) to explore the role of decitabine in this combination treatment regimen. A total of 11 patients (55.0 %) achieved complete remission (CR) after DAA treatment, including 7 of whom reached CR after only one treatment course. The other two patients achieved partial remission. The median overall survival (OS) was 10 months for all 20 patients. The median OS for those who achieved CR was significantly longer than that of patients with no response (NR; P = 0.01 ). The treatment regimen was well tolerated, and there was no treatment-related mortality. The mean levels of P15 ink4b methylation decreased significantly in six patients who achieved CR, whereas very few changes in P15 ink4b methylation were detected for the five patients with NR following DAA treatment. The data from the methyl thiazolyl tetrazolium assays showed that the inhibition rates of AA and DAA for tumor cells were identical. We conclude that induction therapy with DAA for refractory/relapsed de novo AML or MDS/AML achieved high levels of CR and improved OS and demonstrated adequate tolerance. Moreover, the decitabine component of DAA may function through a demethylation effect.
INK4 locus of the tumor-resistant rodent, the naked mole rat, expresses a functional p15/p16 hybrid isoform
Significance The naked mole rat is a longest lived and cancer-resistant rodent. Tumor resistance in the naked mole rat is mediated by signals from the extracellular matrix component hyaluronan triggering the induction of INK4 (inhibitors of cyclin dependent kinase 4) locus expression. The human and mouse INK4 locus encodes three critical tumor-suppressor proteins, p15 ᴵᴺᴷ⁴ᵇ, ARF (alternate reading frame), and p16 ᴵᴺᴷ⁴ᵃ, which are among the most frequently mutated in cancer. Furthermore, p16 ᴵᴺᴷ⁴ᵃ is implicated in aging and senescence. Here, we show that the naked mole rat INK4 locus encodes an additional product, a hybrid between p15 ᴵᴺᴷ⁴ᵇ and p16 ᴵᴺᴷ⁴ᵃ. The novel product, named pALT ᴵᴺᴷ⁴ᵃ/ᵇ, may contribute to tumor resistance and longevity of the naked mole rat. Understanding the regulation of the INK4 locus is critical for cancer and aging research. The naked mole rat ( Heterocephalus glaber ) is a long-lived and tumor-resistant rodent. Tumor resistance in the naked mole rat is mediated by the extracellular matrix component hyaluronan of very high molecular weight (HMW-HA). HMW-HA triggers hypersensitivity of naked mole rat cells to contact inhibition, which is associated with induction of the INK4 (inhibitors of cyclin dependent kinase 4) locus leading to cell-cycle arrest. The INK4a/b locus is among the most frequently mutated in human cancer. This locus encodes three distinct tumor suppressors: p15 ᴵᴺᴷ⁴ᵇ, p16 ᴵᴺᴷ⁴ᵃ, and ARF (alternate reading frame). Although p15 ᴵᴺᴷ⁴ᵇ has its own ORF, p16 ᴵᴺᴷ⁴ᵃ and ARF share common second and third exons with alternative reading frames. Here, we show that, in the naked mole rat, the INK4a/b locus encodes an additional product that consists of p15 ᴵᴺᴷ⁴ᵇ exon 1 joined to p16 ᴵᴺᴷ⁴ᵃ exons 2 and 3. We have named this isoform pALT ᴵᴺᴷ⁴ᵃ/ᵇ (for alternative splicing). We show that pALT ᴵᴺᴷ⁴ᵃ/ᵇ is present in both cultured cells and naked mole rat tissues but is absent in human and mouse cells. Additionally, we demonstrate that pALT ᴵᴺᴷ⁴ᵃ/ᵇ expression is induced during early contact inhibition and upon a variety of stresses such as UV, gamma irradiation-induced senescence, loss of substrate attachment, and expression of oncogenes. When overexpressed in naked mole rat or human cells, pALT ᴵᴺᴷ⁴ᵃ/ᵇ has stronger ability to induce cell-cycle arrest than either p15 ᴵᴺᴷ⁴ᵇ or p16 ᴵᴺᴷ⁴ᵃ. We hypothesize that the presence of the fourth product, pALT ᴵᴺᴷ⁴ᵃ/ᵇ of the INK4a/b locus in the naked mole rat, contributes to the increased resistance to tumorigenesis of this species.
Effects of short-term high-fat overfeeding on genome-wide DNA methylation in the skeletal muscle of healthy young men
Aims/hypothesis Energy-dense diets that are high in fat are associated with a risk of metabolic diseases. The underlying molecular mechanisms could involve epigenetics, as recent data show altered DNA methylation of putative type 2 diabetes candidate genes in response to high-fat diets. We examined the effect of a short-term high-fat overfeeding (HFO) diet on genome-wide DNA methylation patterns in human skeletal muscle. Methods Skeletal muscle biopsies were obtained from 21 healthy young men after ingestion of a short-term HFO diet and a control diet, in a randomised crossover setting. DNA methylation was measured in 27,578 CpG sites/14,475 genes using Illumina's Infinium Bead Array. Candidate gene expression was determined by quantitative real-time PCR. Results HFO introduced widespread DNA methylation changes affecting 6,508 genes (45%), with a maximum methylation change of 13.0 percentage points. The HFO-induced methylation changes were only partly and non-significantly reversed after 6–8 weeks. Alterations in DNA methylation levels primarily affected genes involved in inflammation, the reproductive system and cancer. Few gene expression changes were observed and these had poor correlation to DNA methylation. Conclusions/interpretation The genome-wide DNA methylation changes induced by the short-term HFO diet could have implications for our understanding of transient epigenetic regulation in humans and its contribution to the development of metabolic diseases. The slow reversibility suggests a methylation build-up with HFO, which over time may influence gene expression levels.
Circular non-coding RNA ANRIL modulates ribosomal RNA maturation and atherosclerosis in humans
Circular RNAs (circRNAs) are broadly expressed in eukaryotic cells, but their molecular mechanism in human disease remains obscure. Here we show that circular antisense non-coding RNA in the INK4 locus ( circANRIL ), which is transcribed at a locus of atherosclerotic cardiovascular disease on chromosome 9p21, confers atheroprotection by controlling ribosomal RNA (rRNA) maturation and modulating pathways of atherogenesis. CircANRIL binds to pescadillo homologue 1 (PES1), an essential 60S-preribosomal assembly factor, thereby impairing exonuclease-mediated pre-rRNA processing and ribosome biogenesis in vascular smooth muscle cells and macrophages. As a consequence, circANRIL induces nucleolar stress and p53 activation, resulting in the induction of apoptosis and inhibition of proliferation, which are key cell functions in atherosclerosis. Collectively, these findings identify circANRIL as a prototype of a circRNA regulating ribosome biogenesis and conferring atheroprotection, thereby showing that circularization of long non-coding RNAs may alter RNA function and protect from human disease. Circular RNAs are widely expressed in eukaryotic cells but their functions and mechanisms of action are still being elucidated. Here the authors show that circANRIL modulates rRNA maturation and confers protection again atherosclerosis.
A novel compound, ferulic acid-bound resveratrol, induces the tumor suppressor gene p15 and inhibits the three-dimensional proliferation of colorectal cancer cells
Resveratrol, a phytoalexin present in grapes and other edible foods, has been reported to have beneficial effects against various diseases including cancer. We previously reported that resveratrol and its derivative, caffeic acid-adducted resveratrol, selectively inhibit the three-dimensional (3D) proliferation of a human colorectal cancer cell line, HCT116 with activating KRAS mutation. Herein, we demonstrated that a novel compound, ferulic acid-bound resveratrol, also represses the 3D proliferation of HCT116 cells. We observed that resveratrol conjugated to two ferulic acids represses the 3D proliferation of HCT116 cells more strongly than resveratrol and resveratrol conjugated to one ferulic acid. Resveratrol conjugated to two ferulic acids also inhibited the 3D proliferation of MCF7 human breast cancer cells. We further uncovered that the resveratrol derivative increases the mRNA level of the tumor suppressor p15, a CDK inhibitor that functions as a brake of cell proliferation in HCT116 cells. These results imply that the resveratrol derivative represses 3D proliferation via increasing p15 expression in HCT116 cells.
SP1-induced upregulation of the long noncoding RNA TINCR regulates cell proliferation and apoptosis by affecting KLF2 mRNA stability in gastric cancer
The long noncoding RNA TINCR shows aberrant expression in human squamous carcinomas. However, its expression and function in gastric cancer remain unclear. We report that TINCR is strongly upregulated in human gastric carcinoma (GC), where it was found to contribute to oncogenesis and cancer progression. We also revealed that TINCR overexpression is induced by nuclear transcription factor SP1. Silencing TINCR expression inhibited cell proliferation, colony formation, tumorigenicity and apoptosis promotion, whereas TINCR overexpression promoted cell growth, as documented in the SGC7901 and BGC823 cell lines. Mechanistic analyses indicated that TINCR could bind to STAU1 (staufen1) protein, and influence KLF2 mRNA stability and expression, then KLF2 regulated cyclin-dependent kinase genes CDKN1A/P21 and CDKN2B/P15 transcription and expression, thereby affecting the proliferation and apoptosis of GC cells. Together, our findings suggest that TINCR contributes to the oncogenic potential of GC and may constitute a potential therapeutic target in this disease.
Clonal dynamics towards the development of venetoclax resistance in chronic lymphocytic leukemia
Deciphering the evolution of cancer cells under therapeutic pressure is a crucial step to understand the mechanisms that lead to treatment resistance. To this end, we analyzed whole-exome sequencing data of eight chronic lymphocytic leukemia (CLL) patients that developed resistance upon BCL2-inhibition by venetoclax. Here, we report recurrent mutations in BTG1 (2 patients) and homozygous deletions affecting CDKN2A/B (3 patients) that developed during treatment, as well as a mutation in BRAF and a high-level focal amplification of CD274 ( PD-L1 ) that might pinpoint molecular aberrations offering structures for further therapeutic interventions. BCL2-inhibitor venetoclax is used to treat relapsed/refractory chronic lymphocytic leukemia (CLL). Here, the authors show the clonal dynamics towards venetoclax resistance by performing whole-exome sequencing of 8 CLL patients undergoing venetoclax treatment.
Dominant role of CDKN2B/p15INK4B of 9p21.3 tumor suppressor hub in inhibition of cell-cycle and glycolysis
Human chromosome 9p21.3 is susceptible to inactivation in cell immortalization and diseases, such as cancer, coronary artery disease and type-2 diabetes. Although this locus encodes three cyclin-dependent kinase (CDK) inhibitors (p15 INK4B , p14 ARF and p16 INK4A ), our understanding of their functions and modes of action is limited to the latter two. Here, we show that in vitro p15 INK4B is markedly stronger than p16 INK4A in inhibiting pRb1 phosphorylation, E2F activity and cell-cycle progression. In mice, urothelial cells expressing oncogenic HRas and lacking p15 INK4B , but not those expressing HRas and lacking p16 INK4A , develop early-onset bladder tumors. The potency of CDKN2B/p15 INK4B in tumor suppression relies on its strong binding via key N-terminal residues to and inhibition of CDK4/CDK6. p15 INK4B also binds and inhibits enolase-1, a glycolytic enzyme upregulated in most cancer types. Our results highlight the dual inhibition of p15 INK4B on cell proliferation, and unveil mechanisms whereby p15 INK4B aberrations may underpin cancer and non-cancer conditions. The human chromosome locus 9p21.3 is a tumour suppressor hub which encodes three CDK inhibitors, p15INK4B, p14ARF and p16INK4A. Here, the authors show that p15INK4B inhibits the cell cycle and glycolysis in a murine model of HRas + ‐mediated urothelial carcinoma and has a more relevant role as a tumour suppressor than its neighbouring p16INK4A.
Expression of Linear and Novel Circular Forms of an INK4/ARF-Associated Non-Coding RNA Correlates with Atherosclerosis Risk
Human genome-wide association studies have linked single nucleotide polymorphisms (SNPs) on chromosome 9p21.3 near the INK4/ARF (CDKN2a/b) locus with susceptibility to atherosclerotic vascular disease (ASVD). Although this locus encodes three well-characterized tumor suppressors, p16(INK4a), p15(INK4b), and ARF, the SNPs most strongly associated with ASVD are ∼120 kb from the nearest coding gene within a long non-coding RNA (ncRNA) known as ANRIL (CDKN2BAS). While individuals homozygous for the atherosclerotic risk allele show decreased expression of ANRIL and the coding INK4/ARF transcripts, the mechanism by which such distant genetic variants influence INK4/ARF expression is unknown. Here, using rapid amplification of cDNA ends (RACE) and analysis of next-generation RNA sequencing datasets, we determined the structure and abundance of multiple ANRIL species. Each of these species was present at very low copy numbers in primary and cultured cells; however, only the expression of ANRIL isoforms containing exons proximal to the INK4/ARF locus correlated with the ASVD risk alleles. Surprisingly, RACE also identified transcripts containing non-colinear ANRIL exonic sequences, whose expression also correlated with genotype and INK4/ARF expression. These non-polyadenylated RNAs resisted RNAse R digestion and could be PCR amplified using outward-facing primers, suggesting they represent circular RNA structures that could arise from by-products of mRNA splicing. Next-generation DNA sequencing and splice prediction algorithms identified polymorphisms within the ASVD risk interval that may regulate ANRIL splicing and circular ANRIL (cANRIL) production. These results identify novel circular RNA products emanating from the ANRIL locus and suggest causal variants at 9p21.3 regulate INK4/ARF expression and ASVD risk by modulating ANRIL expression and/or structure.
Diameter and rigidity of multiwalled carbon nanotubes are critical factors in mesothelial injury and carcinogenesis
Multiwalled carbon nanotubes (MWCNTs) have the potential for widespread applications in engineering and materials science. However, because of their needle-like shape and high durability, concerns have been raised that MWCNTs may induce asbestos-like pathogenicity. Although recent studies have demonstrated that MWCNTs induce various types of reactivities, the physicochemical features of MWCNTs that determine their cytotoxicity and carcinogenicity in mesothelial cells remain unclear. Here, we showed that the deleterious effects of nonfunctionalized MWCNTs on human mesothelial cells were associated with their diameter-dependent piercing of the cell membrane. Thin MWCNTs (diameter ∼ 50 nm) with high crystallinity showed mesothelial cell membrane piercing and cytotoxicity in vitro and subsequent inflammogenicity and mesotheliomagenicity in vivo. In contrast, thick (diameter ∼ 150 nm) or tangled (diameter ∼ 2–20 nm) MWCNTs were less toxic, inflammogenic, and carcinogenic. Thin and thick MWCNTs similarly affected macrophages. Mesotheliomas induced by MWCNTs shared homozygous deletion of Cdkn2a/2b tumor suppressor genes, similar to mesotheliomas induced by asbestos. Thus, we propose that different degrees of direct mesothelial injury by thin and thick MWCNTs are responsible for the extent of inflammogenicity and carcinogenicity. This work suggests that control of the diameter of MWCNTs could reduce the potential hazard to human health.