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1.
Front Endocrinol (Lausanne) ; 13: 1015244, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36339418

RESUMO

Background: The focal form of CHI is caused by an autosomal recessive pathogenic variant affecting the paternal homologue of genes ABCC8 or KCNJ11 and a second somatic event specifically occurring in the affected islet of Langerhans. The approach of this study was to integrate the genetic changes occurring in pancreatic focal lesions of CHI at the genomic and transcriptional level. Research Design and Methods: Patients receiving therapeutic surgery and with proven ABCC8 or KCNJ11 pathogenic variants were selected and analyzed for loss of heterozygosity (LOH), changes in copy number and uniparental disomy (UPD) on the short am of chromosome 11 by molecular microarray analysis and methylation-specific MLPA. Gene expression was analyzed by RT-PCR and Massive Analysis of cDNA Ends (MACE). Results: Both genes, ABCC8 and KCNJ11, are located in proximity to the Beckwith-Wiedemann (BWS) imprinting control region on chromosome 11p15. Somatic paternal uniparental isodisomy (UPD) at chromosome 11p was identified as second genetic event in focal lesions resulting in LOH and monoallelic expression of the mutated ABCC8/KCNJ11 alleles. Of five patients with samples available for microarray analysis, the breakpoints of UPD on chromosome 11p were different. Samples of two patients were analyzed further for changes in gene expression. Profound downregulation of growth suppressing genes CDKN1 and H19 was detected in focal lesions whereas growth promoting gene ASCL2 and pancreatic transcription factors of the endocrine cell lineage were upregulated. Conclusions: Paternal UPD on the short arm of chromosome 11 appears to be the major second genetic event specifically within focal lesions of CHI but no common breakpoint for UDP can be delineated. We show for the first time upregulation of growth promoting ASCL2 (achaete-scute homolog 2) suggestive of a driving factor in postnatal focal expansion in addition to downregulation of growth suppressing genes CDKN1C and H19.


Assuntos
Hiperinsulinismo Congênito , Canais de Potássio Corretores do Fluxo de Internalização , Humanos , Canais de Potássio Corretores do Fluxo de Internalização/genética , Hiperinsulinismo Congênito/genética , Hiperinsulinismo Congênito/patologia , Dissomia Uniparental/genética , Perda de Heterozigosidade , Genômica , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Receptores de Sulfonilureias/genética
2.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 39(11): 1279-1282, 2022 Nov 10.
Artigo em Chinês | MEDLINE | ID: mdl-36317219

RESUMO

OBJECTIVE: To assess the association of genomic instability of epithelial cadherin 1 (CDH1) gene and clinicopathological characteristics of gastric cancer. METHODS: In total 120 paraffin-embedded gastric cancer tissue specimen were prepared, and genomic DNA was extracted. The genomic instability of the CDH1 gene was analyzed by immunohistochemistry and silver staining PCR-single-strand conformation polymorphism. RESULTS: The number of information individuals (heterozygotes) was 98 for the D16S752 locus. The detection rates for microsatellite instability (MSI) and loss of heterozygosity (LOH) at the D16S752 locus and the positive rate of CDH1 protein were 19.39%, 16.33% and 51.02%, respectively. The detection rate of MSI in TNM stages I or II was significantly higher than that in stages III or IV (P<0.05) while the detection rate of LOH was significantly lower than that in stages III or IV (P<0.05). The positive rate of CDH1 protein in TNM stages III or IV was significantly lower than that in stages I or II (P<0.05). The detection rate of MSI of cases with lymph node metastasis was significantly lower than that of without lymph node metastasis (P<0.05) while the detection rate of LOH was significantly higher than that without lymph node metastasis (P<0.05). The positive rate of CDH1 protein in patients with lymph node metastasis was significantly lower than that in patients without lymph node metastasis (P<0.05). The positive rate of CDH1 protein in MSI-positive group was significantly higher than that in MSI-negative group (P<0.05), and the positive rate of CDH1 protein in the LOH-positive group was significantly lower than that the LOH-negative group (P<0.05). CONCLUSION: The genomic instability of the CDH1 gene is associated with the progression of gastric cancer. MSI at the D16S752 locus may be used as a molecular marker for early gastric cancer, while LOH at this locus mostly occurs in advanced gastric cancer and can be regarded as an effective indicators for malignancy evaluation and prognosis.


Assuntos
Neoplasias Gástricas , Humanos , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Metástase Linfática , Proteínas Cdh1/genética , Instabilidade de Microssatélites , Perda de Heterozigosidade , Instabilidade Genômica , Repetições de Microssatélites , Antígenos CD/genética , Caderinas/genética
3.
Nat Commun ; 13(1): 6728, 2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36344544

RESUMO

Recurrence is a major cause of death among BRCA1/2 mutation carriers with breast (BrCa) and ovarian cancers (OvCa). Herein we perform multi-omic sequencing on 67 paired primary and recurrent BrCa and OvCa from 27 BRCA1/2 mutation carriers to identify potential recurrence-specific drivers. PARP1 amplifications are identified in recurrences (False Discovery Rate q = 0.05), and PARP1 is significantly overexpressed across primary BrCa and recurrent BrCa and OvCa, independent of amplification status. RNA sequencing analysis finds two BRCA2 isoforms, BRCA2-201/Long and BRCA2-001/Short, respectively predicted to be sensitive and insensitive to nonsense-mediated decay. BRCA2-001/Short is expressed more frequently in recurrences and associated with reduced overall survival in breast cancer (87 vs. 121 months; Hazard Ratio = 2.5 [1.18-5.5]). Loss of heterozygosity (LOH) status is discordant in 25% of patient's primary and recurrent tumors, with switching between both LOH and lack of LOH found. Our study reveals multiple potential drivers of recurrent disease in BRCA1/2 mutation-associated cancer, improving our understanding of tumor evolution and suggesting potential biomarkers.


Assuntos
Neoplasias da Mama , Neoplasias Ovarianas , Feminino , Humanos , Proteína BRCA2/genética , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Perda de Heterozigosidade/genética , Modelos de Riscos Proporcionais , Proteína BRCA1/genética , Mutação , Mutação em Linhagem Germinativa
4.
Cancer Cell ; 40(11): 1276-1278, 2022 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-36379206

RESUMO

A recent Nature study delineates a stepwise genomic evolution during pancreatic cancer development, employing an engineered mutant Kras and heterozygous Trp53 mouse model that identifies cells undergoing Trp53 loss of heterozygosity (LOH). Genetic progression post-Trp53 LOH involves clonal deletions, then genome doubling and subsequent accumulation of subclonal gains and amplifications.


Assuntos
Neoplasias Pancreáticas , Proteína Supressora de Tumor p53 , Camundongos , Animais , Proteína Supressora de Tumor p53/genética , Perda de Heterozigosidade , Neoplasias Pancreáticas/genética , Evolução Molecular
5.
Anticancer Res ; 42(11): 5257-5263, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36288893

RESUMO

BACKGROUND/AIM: Tumor cell lines are essential tools in understanding the molecular mechanisms underlying cancer biology and therapeutic responses. Poly (ADP-ribose) polymerase inhibitors (PARPi) kill tumor cells harboring pathogenic mutations of BRCA DNA repair-associated genes 1/2 (BRCA1/2) and are approved to treat ovarian and metastatic breast cancer. Loss of heterozygosity (LOH) of the wild-type BRCA1/2 locus is suspected to increase cellular response to PARPi. To better elucidate the molecular mechanisms underlying PARPi sensitivity and resistance, this study assessed the responses of various pathogenic BRCA1/2-mutant cell lines to the PARPi talazoparib. MATERIALS AND METHODS: Mutant cell lines were extracted and cultured from four surgically resected, human breast cancer specimens with different pathogenic BRCA1/2, one normal breast specimen and one ovarian cancer specimen. Mutation analysis was performed on all cell lines using genomic DNA extraction and polymerase chain reaction. Following treatment with talazoparib, cell growth was assessed using tetrazolium salt and half-maximal inhibitory concentration values were determined. RESULTS: A partial correlation between different variants of pathogenic BRCA1/2 mutation and talazoparib susceptibility was found, with five of the cell lines exhibiting sensitivity to talazoparib. The most sensitive cell-line to talazoparib had LOH for BRCA1, while the breast cancer cell line harboring BRCA2 LOH was resistant to talazoparib. CONCLUSION: This study suggests that LOH does not necessarily correlate with PARPi efficacy. These results lay a foundation for future studies to utilize these novel cell lines to further elucidate the underlying molecular mechanisms of PARPi resistance and reveal new potential drug targets.


Assuntos
Neoplasias da Mama , Ribose , Feminino , Humanos , Ribose/uso terapêutico , Ftalazinas/farmacologia , Ftalazinas/uso terapêutico , Proteína BRCA1/genética , Proteína BRCA2/genética , Inibidores de Poli(ADP-Ribose) Polimerases/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Biomarcadores , Perda de Heterozigosidade , Sais de Tetrazólio , Difosfato de Adenosina
6.
Mol Biol Evol ; 39(11)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36205042

RESUMO

The appearance of genomic variations such as loss of heterozygosity (LOH) has a significant impact on phenotypic diversity observed in a population. Recent large-scale yeast population genomic surveys have shown a high frequency of these events in natural isolates and more particularly in polyploids. However, the frequency, extent, and spectrum of LOH in polyploid organisms have never been explored and are poorly characterized to date. Here, we accumulated 5,163 LOH events over 1,875 generations in 76 mutation accumulation (MA) lines comprising nine natural heterozygous diploid, triploid, and tetraploid natural S. cerevisiae isolates from different ecological and geographical origins. We found that the rate and spectrum of LOH are variable across ploidy levels. Of the total accumulated LOH events, 8.5%, 21%, and 70.5% of them were found in diploid, triploid, and tetraploid MA lines, respectively. Our results clearly show that the frequency of generated LOH events increases with ploidy level. In fact, the cumulative LOH rates were estimated to be 9.3 × 10-3, 2.2 × 10-2, and 8.4 × 10-2 events per division for diploids, triploids, and tetraploids, respectively. In addition, a clear bias toward the accumulation of interstitial and short LOH tracts is observed in triploids and tetraploids compared with diploids. The variation of the frequency and spectrum of LOH events across ploidy level could be related to the genomic instability, characterizing higher ploidy isolates.


Assuntos
Saccharomyces cerevisiae , Tetraploidia , Saccharomyces cerevisiae/genética , Triploidia , Ploidias , Perda de Heterozigosidade
7.
Breast Cancer Res Treat ; 196(2): 355-361, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36094610

RESUMO

PURPOSE: Cancer risks conferred by germline, heterozygous, ATM pathogenic/likely pathogenic variants (PSVs) are yet to be consistently determined. The current study assessed these risks by analysis of a large dataset of ATM heterozygote loss of function (LOF) and missense PSV carriers tested with a multigene panel (MGP). METHODS: De-identified data of all individuals who underwent ATM sequencing as part of MGP between October 2015 and February 2020 were reviewed. In cancer cases, rates for the six most prevalent variants and for all LOF and missense PSV combined were compared with rates of the same PSV in ethnically matched, healthy population controls. Statistical analysis included Chi-square tests and odds ratios calculations. RESULTS: For female breast cancer cases, LOF )1794/219,269) and missense (301/219,269) ATM PSVs were seen at higher rates compared to gnomAD non-cancer controls (n = 157/56,001 and n = 27/61,208; p < 0.00001, respectively). Notably, the rate of the c.103C > T variant was higher in controls than in breast cancer cases [p = 0.001; OR 0.31 (95% CI 0.1-0.6)]. For all cancer cases combined, compared with non-cancer population controls, LOF (n = 143) and missense (n = 15) PSVs reported in both datasets were significantly more prevalent in cancer cases [ORLOF 1.7 (95% 1.5-1.9) ORmissense 3.0 (95% CI 2.3-4); p = 0.0001]. CONCLUSION: Both LOF and missense heterozygous ATM PSVs are more frequently detected in cases of several cancer types (breast, ovarian, prostate, lung, pancreatic) compared with healthy population controls. However, not all ATM PSVs confer an increased cancer risk (e.g., breast).


Assuntos
Neoplasias da Mama , Predisposição Genética para Doença , Feminino , Humanos , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Mutação de Sentido Incorreto , Perda de Heterozigosidade , Heterozigoto , Proteínas Mutadas de Ataxia Telangiectasia/genética
8.
Mol Cell ; 82(20): 3781-3793.e7, 2022 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-36099913

RESUMO

Germline mutations in the BRCA genes are associated with a higher risk of carcinogenesis, which is linked to an increased mutation rate and loss of the second unaffected BRCA allele (loss of heterozygosity, LOH). However, the mechanisms triggering mutagenesis are not clearly understood. The BRCA genes contain high numbers of repetitive DNA sequences. We detected replication forks stalling, DNA breaks, and deletions at these sites in haploinsufficient BRCA cells, thus identifying the BRCA genes as fragile sites. Next, we found that stalled forks are repaired by error-prone pathways, such as microhomology-mediated break-induced replication (MMBIR) in haploinsufficient BRCA1 breast epithelial cells. We detected MMBIR mutations in BRCA1 tumor cells and noticed deletions-insertions (>50 bp) at the BRCA1 genes in BRCA1 patients. Altogether, these results suggest that under stress, error-prone repair of stalled forks is upregulated and induces mutations, including complex genomic rearrangements at the BRCA genes (LOH), in haploinsufficient BRCA1 cells.


Assuntos
Proteína BRCA1 , Replicação do DNA , Humanos , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Reparo do DNA , Mutagênese , Genes BRCA1 , Perda de Heterozigosidade , Proteína BRCA2/genética , Proteína BRCA2/metabolismo
9.
Br J Cancer ; 127(10): 1843-1857, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36097176

RESUMO

BACKGROUND: A vestibular schwannoma (VS) is a relatively rare, benign tumour of the eighth cranial nerve, often involving alterations to the gene NF2. Previous mathematical models of schwannoma incidence have not attempted to account for alterations in specific genes, and could not distinguish between nonsense mutations and loss of heterozygosity (LOH). METHODS: Here, we present a mechanistic approach to modelling initiation and malignant transformation in schwannoma. Each parameter is associated with a specific gene or mechanism operative in Schwann cells, and can be determined by combining incidence data with empirical frequencies of pathogenic variants and LOH. RESULTS: This results in new estimates for the base-pair mutation rate u = 4.48 × 10-10 and the rate of LOH = 2.03 × 10-6/yr in Schwann cells. In addition to new parameter estimates, we extend the approach to estimate the risk of both spontaneous and radiation-induced malignant transformation. DISCUSSION: We conclude that radiotherapy is likely to have a negligible excess risk of malignancy for sporadic VS, with a possible exception of rapidly growing tumours.


Assuntos
Neurilemoma , Neuroma Acústico , Humanos , Neuroma Acústico/epidemiologia , Neuroma Acústico/genética , Neuroma Acústico/patologia , Neurilemoma/genética , Perda de Heterozigosidade , Transformação Celular Neoplásica , Modelos Teóricos
11.
Sci Adv ; 8(32): eabo2389, 2022 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-35947664

RESUMO

An alarming rise in young onset colorectal cancer (CRC) has been reported; however, the underlying molecular mechanism remains undefined. Suspected risk factors of young onset CRC include environmental aspects, such as lifestyle and dietary factors, which are known to affect the circadian clock. We find that both genetic disruption and environmental disruption of the circadian clock accelerate Apc-driven CRC pathogenesis in vivo. Using an intestinal organoid model, we demonstrate that clock disruption promotes transformation by driving Apc loss of heterozygosity, which hyperactivates Wnt signaling. This up-regulates c-Myc, a known Wnt target, which drives heightened glycolytic metabolism. Using patient-derived organoids, we show that circadian rhythms are lost in human tumors. Last, we identify that variance between core clock and Wnt pathway genes significantly predicts the survival of patients with CRC. Overall, our findings demonstrate a previously unidentified mechanistic link between clock disruption and CRC, which has important implications for young onset cancer prevention.


Assuntos
Relógios Circadianos , Neoplasias Colorretais , Relógios Circadianos/genética , Ritmo Circadiano/genética , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Humanos , Perda de Heterozigosidade , Organoides/metabolismo , Via de Sinalização Wnt
12.
Nature ; 608(7924): 795-802, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35978189

RESUMO

Although p53 inactivation promotes genomic instability1 and presents a route to malignancy for more than half of all human cancers2,3, the patterns through which heterogenous TP53 (encoding human p53) mutant genomes emerge and influence tumorigenesis remain poorly understood. Here, in a mouse model of pancreatic ductal adenocarcinoma that reports sporadic p53 loss of heterozygosity before cancer onset, we find that malignant properties enabled by p53 inactivation are acquired through a predictable pattern of genome evolution. Single-cell sequencing and in situ genotyping of cells from the point of p53 inactivation through progression to frank cancer reveal that this deterministic behaviour involves four sequential phases-Trp53 (encoding mouse p53) loss of heterozygosity, accumulation of deletions, genome doubling, and the emergence of gains and amplifications-each associated with specific histological stages across the premalignant and malignant spectrum. Despite rampant heterogeneity, the deletion events that follow p53 inactivation target functionally relevant pathways that can shape genomic evolution and remain fixed as homogenous events in diverse malignant populations. Thus, loss of p53-the 'guardian of the genome'-is not merely a gateway to genetic chaos but, rather, can enable deterministic patterns of genome evolution that may point to new strategies for the treatment of TP53-mutant tumours.


Assuntos
Carcinogênese , Progressão da Doença , Genes p53 , Genoma , Perda de Heterozigosidade , Neoplasias Pancreáticas , Proteína Supressora de Tumor p53 , Adenocarcinoma/genética , Adenocarcinoma/patologia , Animais , Carcinogênese/genética , Carcinogênese/patologia , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patologia , Evolução Molecular , Deleção de Genes , Genes p53/genética , Genoma/genética , Camundongos , Modelos Genéticos , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Proteína Supressora de Tumor p53/genética
13.
Am J Hum Genet ; 109(10): 1909-1922, 2022 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-36044892

RESUMO

The transmembrane protein TMEM147 has a dual function: first at the nuclear envelope, where it anchors lamin B receptor (LBR) to the inner membrane, and second at the endoplasmic reticulum (ER), where it facilitates the translation of nascent polypeptides within the ribosome-bound TMCO1 translocon complex. Through international data sharing, we identified 23 individuals from 15 unrelated families with bi-allelic TMEM147 loss-of-function variants, including splice-site, nonsense, frameshift, and missense variants. These affected children displayed congruent clinical features including coarse facies, developmental delay, intellectual disability, and behavioral problems. In silico structural analyses predicted disruptive consequences of the identified amino acid substitutions on translocon complex assembly and/or function, and in vitro analyses documented accelerated protein degradation via the autophagy-lysosomal-mediated pathway. Furthermore, TMEM147-deficient cells showed CKAP4 (CLIMP-63) and RTN4 (NOGO) upregulation with a concomitant reorientation of the ER, which was also witnessed in primary fibroblast cell culture. LBR mislocalization and nuclear segmentation was observed in primary fibroblast cells. Abnormal nuclear segmentation and chromatin compaction were also observed in approximately 20% of neutrophils, indicating the presence of a pseudo-Pelger-Huët anomaly. Finally, co-expression analysis revealed significant correlation with neurodevelopmental genes in the brain, further supporting a role of TMEM147 in neurodevelopment. Our findings provide clinical, genetic, and functional evidence that bi-allelic loss-of-function variants in TMEM147 cause syndromic intellectual disability due to ER-translocon and nuclear organization dysfunction.


Assuntos
Deficiência Intelectual , Anormalidades Musculoesqueléticas , Anomalia de Pelger-Huët , Núcleo Celular/genética , Criança , Cromatina , Humanos , Deficiência Intelectual/genética , Perda de Heterozigosidade , Anomalia de Pelger-Huët/genética
14.
Am J Med Genet A ; 188(12): 3531-3534, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35975723

RESUMO

Bi-allelic loss-of-function variants in Von Willebrand factor type A (VWA1) were recently discovered to lead to an early onset motor neuropathy or neuromyopathy. What makes this discovery particularly notable is the high frequency of one of the VWA1 (NM_022834.5) founder variants, c.62_71dup (p.Gly25ArgfsTer74), which nears 0.01% in European populations, and suggests that there may be a wide spectrum of disease features and severity. Here, we report two cases from nonconsanguineous families in North America that presented in early childhood with lower extremity weakness and prominent foot deformities, and were found to carry bi-allelic variants in VWA1. We draw focus to upper motor neuron signs and abnormal gait phenotypes as presenting symptoms in VWA1-related disorder and expand the clinical and molecular spectrum.


Assuntos
Perda de Heterozigosidade , Neurônios Motores , Pré-Escolar , Humanos , Alelos , Fenótipo , Marcha/genética , Proteínas da Matriz Extracelular
15.
Int J Mol Sci ; 23(15)2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35955663

RESUMO

Polyploidy is common in cancer cells and has implications for tumor progression and resistance to therapies, but it is unclear whether it is an adaptation of the tumor or the non-adaptive effect of genomic instability. I discuss the possibility that polyploidy reduces the deleterious effects of loss of heterozygosity, which arises as a consequence of mitotic recombination, and which in diploid cells leads instead to the rapid loss of complementation of recessive deleterious mutations. I use computational predictions of loss of heterozygosity to show that a population of diploid cells dividing by mitosis with recombination can be easily invaded by mutant polyploid cells or cells that divide by endomitosis, which reduces loss of complementation, or by mutant cells that occasionally fuse, which restores heterozygosity. A similar selective advantage of polyploidy has been shown for the evolution of different types of asexual reproduction in nature. This provides an adaptive explanation for cyclical ploidy, mitotic slippage and cell fusion in cancer cells.


Assuntos
Neoplasias , Poliploidia , Heterozigoto , Humanos , Perda de Heterozigosidade , Mitose/genética , Neoplasias/genética , Reprodução Assexuada/genética
16.
Cancer Genet ; 266-267: 69-73, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35802949

RESUMO

Chromosomal aberrations are among the most important prognostic parameters in AML, and conventional cytogenetic analysis remains essential for risk stratification. In this report, we describe an adult male patient with a high percentage of circulating blasts, pathologically confirmed as AML with maturation. Cytogenetic analysis of a bone marrow sample revealed heptasomy 21 and trisomy 13 within a complex karyotype of 52,XY,der(2)t(2;13)(q33.3;q32.1),+13,+21,+21,+21,+21,+21 in all 20 cells examined, which was confirmed by metaphase FISH. Chromosomal microarray analysis (CMA) revealed complete loss of heterozygosity (LOH) of chromosome 21, supporting a common origin. In addition, LOH of chromosome 1p, trisomy 13, and partial tetrasomy of 13q and partial monosomy of 2q as a result of an unbalanced translocation between chromosomes 2 and 13 were observed. Molecular analysis identified two pathogenic missense variants: RUNX1 p.D198Y and SRSF2 p.P95R. The clonal allele ratio of RUNX1 p.D198Y was consistent with all copies of chromosome 21 in the leukemic clone carrying the mutation. Within the medical literature, there are no reports of heptasomy 21 for comparison; however, there are reports of AML with either polysomy 21 or trisomy 13. Our results suggest that even relatively 'common' AML aneuploidies may be associated with much more complex genomic changes, including loss of heterozygosity, which impact prognosis.


Assuntos
Subunidade alfa 2 de Fator de Ligação ao Core , Leucemia Mieloide Aguda , Aberrações Cromossômicas , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Perda de Heterozigosidade , Masculino , Mutação/genética , Trissomia , Síndrome da Trissomia do Cromossomo 13
17.
Comput Math Methods Med ; 2022: 5508301, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35855837

RESUMO

Homologous recombination deficiency which is currently measured by the homologous recombination deficiency (HRD) score including score of telomeric allelic imbalance (TAI), large-scale transition (LST), and loss of heterozygosity (LOH) is highly related with sensitivity to platinum-containing drug and PARP inhibitors. DNA helicases are essential components for the homologous recombination repair process in which DNA helicases unwind double-strand DNA utilizing ATP hydrolysis. In our study, the correlation between the expression of DNA helicase genes and HRD score in breast cancer was analyzed. The overexpression in half of the DNA helicase genes was found to be highly correlated with a high HRD score both in BRCA-mutated and BRCA wild-type breast cancer. Moreover, HRD score can be predicted by a linear function contributed by five DNA helicase genes. In conclusion, our study revealed a close relation between the overexpression of certain DNA helicase genes and the deficiency of homologous recombination repair in breast cancer.


Assuntos
Neoplasias da Mama , Neoplasias da Mama/genética , DNA Helicases/genética , Feminino , Recombinação Homóloga , Humanos , Perda de Heterozigosidade , Inibidores de Poli(ADP-Ribose) Polimerases
18.
Am J Hum Genet ; 109(8): 1421-1435, 2022 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-35830857

RESUMO

PPFIBP1 encodes for the liprin-ß1 protein, which has been shown to play a role in neuronal outgrowth and synapse formation in Drosophila melanogaster. By exome and genome sequencing, we detected nine ultra-rare homozygous loss-of-function variants in 16 individuals from 12 unrelated families. The individuals presented with moderate to profound developmental delay, often refractory early-onset epilepsy, and progressive microcephaly. Further common clinical findings included muscular hyper- and hypotonia, spasticity, failure to thrive and short stature, feeding difficulties, impaired vision, and congenital heart defects. Neuroimaging revealed abnormalities of brain morphology with leukoencephalopathy, ventriculomegaly, cortical abnormalities, and intracranial periventricular calcifications as major features. In a fetus with intracranial calcifications, we identified a rare homozygous missense variant that by structural analysis was predicted to disturb the topology of the SAM domain region that is essential for protein-protein interaction. For further insight into the effects of PPFIBP1 loss of function, we performed automated behavioral phenotyping of a Caenorhabditis elegans PPFIBP1/hlb-1 knockout model, which revealed defects in spontaneous and light-induced behavior and confirmed resistance to the acetylcholinesterase inhibitor aldicarb, suggesting a defect in the neuronal presynaptic zone. In conclusion, we establish bi-allelic loss-of-function variants in PPFIBP1 as a cause of an autosomal recessive severe neurodevelopmental disorder with early-onset epilepsy, microcephaly, and periventricular calcifications.


Assuntos
Epilepsia , Microcefalia , Malformações do Sistema Nervoso , Transtornos do Neurodesenvolvimento , Acetilcolinesterase/genética , Animais , Drosophila melanogaster/genética , Epilepsia/genética , Perda de Heterozigosidade , Microcefalia/genética , Transtornos do Neurodesenvolvimento/genética , Linhagem
19.
Microb Genom ; 8(6)2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35748878

RESUMO

Trypanosoma cruzi the causative agent of Chagas disease shows a marked genetic diversity and divided into at least six Discrete Typing Units (DTUs). High intra genetic variability has been observed in the TcI DTU, the most widely distributed DTU, where patterns of genomic diversity can provide information on ecological and evolutionary processes driving parasite population structure and genome organization. Chromosomal aneuploidies and rearrangements across multigene families represent an evidence of T. cruzi genome plasticity. We explored genomic diversity among 18 Colombian T. cruzi I clones and 15 T. cruzi I South American strains. Our results confirm high genomic variability, heterozygosity and presence of a clade compatible with the TcIdom genotype, described for strains from humans in Colombia and Venezuela. TcI showed high structural plasticity across the geographical region studied. Differential events of whole and segmental aneuploidy (SA) along chromosomes even between clones from the same strain were found and corroborated by the depth and allelic frequency. We detected loss of heterozygosity (LOH) events in different chromosomes, however, the size and location of segments under LOH varied between clones. Genes adjacent to breakpoints were evaluated, and retrotransposon hot spot genes flanked the beginning of segmental aneuploidies. Our results suggest that T. cruzi genomes, like those of Leishmania, may have a highly unstable structure and there is now an urgent need to design experiments to explore any potential adaptive role for the plasticity observed.


Assuntos
Doença de Chagas , Trypanosoma cruzi , Aneuploidia , Doença de Chagas/parasitologia , Variação Genética , Humanos , Perda de Heterozigosidade , Trypanosoma cruzi/genética
20.
Int J Mol Sci ; 23(12)2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35743139

RESUMO

Loss of heterozygosity (LOH) for KRAS, in which a wild-type KRAS allele is progressively lost, promotes invasive and migratory abilities of pancreatic ductal adenocarcinoma (PDAC) cells and tissues. Moreover, the occurrence of KrasG12D-LOH activates nonclassical glutamine metabolism, which is related to the malignant behavior of PDAC cells. Herein, we aim to demonstrate the regulatory link between hypoxia-inducible factor-2α (HIF-2α) and glutamine metabolism that mediates malignant phenotypes in KrasG12D-LOH PDAC cells. HIF-2α-shRNA knockdown lentivirus transfection and metabolite analysis were performed in KrasG12D-LOH and KrasG12D cell lines, respectively. Cell proliferation, migration, and invasion were examined using Cell Counting Kit-8, colony formation, and Transwell assays. Cell cycle phase and apoptosis were determined using flow cytometry. Western blotting and real-time quantitative PCR were also performed. Additionally, a subcutaneous xenograft mouse model was established. LOH stimulated HIF-2α activity and transactivated c-Myc, which has a central regulatory effect on glutamine metabolism independent of hypoxia. Meanwhile, HIF-2α silencing repressed KrasG12D-LOH PDAC cell proliferation, invasion, and migration. HIF-2α knockdown inhibited glutamine uptake and GOT1 expression via a c-Myc-dependent pathway. Collectively, KrasG12D-LOH can activate HIF-2α to regulate c-Myc-mediated glutamine metabolism and promote malignant phenotypes. Moreover, targeting HIF-2α-c-Myc regulated nonclassical glutamine metabolism, providing a new therapeutic perspective for KrasG12D-LOH PDAC.


Assuntos
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Carcinoma Ductal Pancreático/patologia , Linhagem Celular Tumoral , Proliferação de Células/genética , Glutamina/metabolismo , Humanos , Hipóxia , Perda de Heterozigosidade , Camundongos , Neoplasias Pancreáticas/patologia , Fenótipo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo
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