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result(s) for
"Mai, Sabine"
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Lamin A/C: Function in Normal and Tumor Cells
2020
This review is focused on lamin A/C, a nuclear protein with multiple functions in normal and diseased cells. Its functions, as known to date, are summarized. This summary includes its role in maintaining a cell’s structural stability, cell motility, mechanosensing, chromosome organization, gene regulation, cell differentiation, DNA damage repair, and telomere protection. As lamin A/C has a variety of critical roles within the cell, mutations of the lamin A/C gene and incorrect processing of the protein results in a wide variety of diseases, ranging from striated muscle disorders to accelerated aging diseases. These diseases, collectively termed laminopathies, are also touched upon. Finally, we review the existing evidence of lamin A/C’s deregulation in cancer. Lamin A/C deregulation leads to various traits, including genomic instability and increased tolerance to mechanical insult, which can lead to more aggressive cancer and poorer prognosis. As lamin A/C’s expression in specific cancers varies widely, currently known lamin A/C expression in various cancers is reviewed. Additionally, Lamin A/C’s potential as a biomarker in various cancers and as an aid in more accurately diagnosing intermediate Gleason score prostate cancers is also discussed.
Journal Article
Three-Dimensional Organization of Telomeres: An Emerging Prognostic Biomarker in Multiple Myeloma
2025
A crucial role of genome instability and telomeric dysfunction was demonstrated in multiple cancers, including multiple myeloma (MM). MM accounts for approximately 10% of all hematologic malignancies and includes asymptomatic pre-malignant monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). Due to the highly heterogeneous nature of the disease, there is an ongoing need for precise risk stratification and subsequent development of risk-adapted treatment strategies at every stage of disease and during disease progression. Telomere numbers, intensity, aggregates, and spatial arrangement within the nucleus were identified as prognostic biomarkers. Recent studies demonstrated that the three-dimensional (3D) analysis of key telomeric parameters is a reliable marker of the high risk of relapse in newly diagnosed MM (NDMM) patients and can predict the risk of progression of SMM patients. Telomeric parameters of malignant MM cells from the peripheral blood and bone marrow were similar, suggesting that 3D telomere profiling may assess MRD in liquid biopsies of MM patients. This review focuses on the prognostic value of 3D telomere profiling in MM. 3D spatial telomere analysis may potentially address a critical unmet clinical need in managing MM and, if incorporated into current guidelines, help to accurately predict disease status, progression risk, overall survival, and response to treatment.
Journal Article
Cementless short-stem total hip arthroplasty in the elderly patient - is it a safe option?: a prospective multicentre observational study
2019
Background
Due to its bone preserving philosophy, short-stem total hip arthroplasty (THA) has primarily been recommended for young and active patients. However, there may be benefits for elderly patients given a less invasive operative technique due to the short curved implant design. The purpose of this study was to compare the clinical and radiological outcomes as well as perioperative complications of a calcar-guided short stem between a young (< 60 years) and a geriatric (> 75 years) population.
Methods
Data were collected in a total of 5 centers, and 400 short-stems were included as part of a prospective multicentre observational study between 2010 and 2014 with a mean follow-up of 49.2 months. Preoperative femur morphology was analysed using the Dorr classification. Clinical and radiological outcomes were assessed in both groups as well as perioperative complications, rates and reasons for stem revision.
Results
No differences were found for the mean visual analogue scale (VAS) values of rest pain, load pain, and satisfaction, whereas Harris Hip Score (HHS) was slightly better in the young group. Comparing both groups, none of the radiological parameters that were assessed (stress-shielding, cortical hypertrophy, radiolucency, osteolysis) reached differences of statistical significance. While in young patients aseptic loosening is the main cause of implant failure, in the elderly group particularly postoperative periprosthetic fractures due to accidental fall have to be considered to be of high risk. The incidence of periprosthetic fractures was found to be 0% in Dorr type A femurs, whereas in Dorr types B and C fractures occurred in 2.1 and 22.2% respectively.
Conclusions
Advanced age alone is not necessarily to be considered as contra-indications for calcar-guided short-stem THA, although further follow-up is needed. However, markedly reduced bone quality with femur morphology of Dorr type C seems to be associated with increased risk for postoperative periprosthetic fractures, thus indication should be limited to Dorr types A and B.
Trial registration
German Clinical Trials Register;
DRKS00012634
, 07.07.2017 (retrospectively registered).
Journal Article
Cyclin E amplification/overexpression is a mechanism of trastuzumab resistance in HER2⁺ breast cancer patients
by
Guzmán, Marta
,
Serra, Violeta
,
Mai, Sabine
in
Antibodies, Monoclonal - pharmacology
,
Antibodies, Monoclonal, Humanized
,
apoptosis
2011
Clinical benefits from trastuzumab and other anti-HER2 therapies in patients with HER2 amplified breast cancer remain limited by primary or acquired resistance. To identify potential mechanisms of resistance, we established trastuzumab-resistant HER2 amplified breast cancer cells by chronic exposure to trastuzumab treatment. Genomewide copy-number variation analyses of the resistant cells compared with parental cells revealed a focal amplification of genomic DNA containing the cyclin E gene. In a cohort of 34 HER2⁺ patients treated with trastuzumab-based therapy, we found that cyclin E amplification/overexpression was associated with a worse clinical benefit (33.3% compared with 87.5%, P < 0.02) and a lower progression-free survival (6 mo vs. 14 mo, P < 0.002) compared with nonoverexpressing cyclin E tumors. To dissect the potential role of cyclin E in trastuzumab resistance, we studied the effects of cyclin E overexpression and cyclin E suppression. Cyclin E overexpression resulted in resistance to trastuzumab both in vitro and in vivo. Inhibition of cyclin E activity in cyclin E-amplified trastuzumab resistant clones, either by knockdown of cyclin E expression or treatment with cyclin-dependent kinase 2 (CDK2) inhibitors, led to a dramatic decrease in proliferation and enhanced apoptosis. In vivo, CDK2 inhibition significantly reduced tumor growth of trastuzumab-resistant xenografts. Our findings point to a causative role for cyclin E overexpression and the consequent increase in CDK2 activity in trastuzumab resistance and suggest that treatment with CDK2 inhibitors may be a valid strategy in patients with breast tumors with HER2 and cyclin E coamplification/overexpression.
Journal Article
Regulatory role of cathepsin L in induction of nuclear laminopathy in Alzheimer’s disease
by
Shcholok, Tetiana
,
Contu, Fabio
,
Mai, Sabine
in
acetylation
,
Alzheimer Disease - genetics
,
Alzheimer Disease - physiopathology
2022
Experimental and clinical therapies in the field of Alzheimer's disease (AD) have focused on elimination of extracellular amyloid beta aggregates or prevention of cytoplasmic neuronal fibrillary tangles formation, yet these approaches have been generally ineffective. Interruption of nuclear lamina integrity, or laminopathy, is a newly identified concept in AD pathophysiology. Unraveling the molecular players in the induction of nuclear lamina damage may lead to identification of new therapies. Here, using 3xTg and APP/PS1 mouse models of AD, and in vitro model of amyloid beta42 (Aβ42) toxicity in primary neuronal cultures and SH‐SY5Y neuroblastoma cells, we have uncovered a key role for cathepsin L in the induction of nuclear lamina damage. The applicability of our findings to AD pathophysiology was validated in brain autopsy samples from patients. We report that upregulation of cathepsin L is an important process in the induction of nuclear lamina damage, shown by lamin B1 cleavage, and is associated with epigenetic modifications in AD pathophysiology. More importantly, pharmacological targeting and genetic knock out of cathepsin L mitigated Aβ42 induced lamin B1 degradation and downstream structural and molecular changes. Affirming these findings, overexpression of cathepsin L alone was sufficient to induce lamin B1 cleavage. The proteolytic activity of cathepsin L on lamin B1 was confirmed using mass spectrometry. Our research identifies cathepsin L as a newly identified lamin B1 protease and mediator of laminopathy observed in AD. These results uncover a new aspect in the pathophysiology of AD that can be pharmacologically prevented, raising hope for potential therapeutic interventions. Aβ42 works by binding to cell membrane, interacting with receptors, forming channel‐like structure or by directly entering into the cells to interact intracellular targets. Treatment of Aβ42 did not induce apoptosis, rather induced lysosomal membrane permeabilization leading to release of lysosomal cathepsins. Cathepsin L cleaves nuclear LB1 and eventually evokes nuclear deformation/invagination. This results in exposing lamin‐associated histones susceptible for post‐translational modifications. The consequences of histone modifications deserve further studies.
Journal Article
Three-dimensional nuclear telomere architecture and differential expression of aurora kinase genes in chronic myeloid leukemia to measure cell transformation
by
Pozzo, Aline Rangel
,
Merfort, Lismeri Wuicik
,
Mai, Sabine
in
Aneuploidy
,
Antibodies
,
Aurora kinase
2022
Background
Telomere dysfunction results in aneuploidy, and ongoing chromosomal abnormalities. The three-dimensional (3D) nuclear organization of telomeres allows for a distinction between normal and tumor cells. On the other hand, aurora kinase genes (
AURKA
and
AURKB
) play an important role regulating the cell cycle. A correlation between overexpression of aurora kinase genes and clinical aggressiveness has been demonstrated in different types of neoplasias. To better understand cellular and molecular mechanisms of CML evolution, it was examined telomere dysfunction (alterations in the 3D nuclear telomere architecture), and the expression levels of
AURKA
and
AURKB
genes in two clinical distinct subgroups of CML samples, from the same patient.
Methods
Eighteen CML patients, in total, 36 bone marrow samples (18 patients,
chronic
vs.
accelerated
/
blast phase
) were eligible for 3D telomeric investigations. Quantitative 3D imaging, cytologic diagnosis and cytogenetic determination of additional chromosomal abnormalities were assessed according to standard protocols.
Results
Using TeloView software, two CML subgroups were defined based on their 3D telomeric profiles, reflecting the different stages of the disease (
chronic
vs.
accelerated
/
blast phase
). Statistical analyses showed significant differences between the CML subgroups (
p
< 0.001). We also found that
AURKA
and
AURKB
mRNA were expressed at significantly higher levels in both CML subgroups, when compared with healthy donors. Our findings suggest that the evolution of CML progresses from a low to a high level of telomere dysfunction, that is, from an early stage to a more aggressive stage, followed by disease transformation, as demonstrated by telomere, additional chromosomal abnormalities, and gene expression profile dynamics.
Conclusions
Thus, we demonstrated that 3D telomere organization, in accordance with the genomic instability observed in CML samples were able to distinguish subgroup CML patients. Classifying CML patients based on these characteristics might represent an important strategy to define better therapeutic strategies.
Journal Article
Genetic Landscape of Papillary Thyroid Carcinoma and Nuclear Architecture: An Overview Comparing Pediatric and Adult Populations
by
Vaisman, Fernanda
,
Caria, Paola
,
Cerutti, Janete M.
in
Genetic aspects
,
Review
,
Thyroid cancer
2020
Thyroid cancer is a rare malignancy in the pediatric population that is highly associated with disease aggressiveness and advanced disease stages when compared to adult population. The biological and molecular features underlying pediatric and adult thyroid cancer pathogenesis could be responsible for differences in the clinical presentation and prognosis. Despite this, the clinical assessment and treatments used in pediatric thyroid cancer are the same as those implemented for adults and specific personalized target treatments are not used in clinical practice. In this review, we focus on papillary thyroid carcinoma (PTC), which represents 80–90% of all differentiated thyroid carcinomas. PTC has a high rate of gene fusions and mutations, which can influence the histologic subtypes in both children and adults. This review also highlights telomere-related genomic instability and changes in nuclear organization as novel biomarkers for thyroid cancers.
Journal Article
AI-Powered Spectral Imaging for Virtual Pathology Staining
by
Soker, Adam
,
Almagor, Maya
,
Mai, Sabine
in
Artificial intelligence
,
artificial intelligence in medicine
,
Biopsy
2025
Pathological analysis of tissue biopsies remains the gold standard for diagnosing cancer and other diseases. However, this is a time-intensive process that demands extensive training and expertise. Despite its importance, it is often subjective and not entirely error-free. Over the past decade, pathology has undergone two major transformations. First, the rise in whole slide imaging has enabled work in front of a computer screen and the integration of image processing tools to enhance diagnostics. Second, the rapid evolution of Artificial Intelligence has revolutionized numerous fields and has had a remarkable impact on humanity. The synergy of these two has paved the way for groundbreaking research aiming for advancements in digital pathology. Despite encouraging research outcomes, AI-based tools have yet to be actively incorporated into therapeutic protocols. This is primary due to the need for high reliability in medical therapy, necessitating a new approach that ensures greater robustness. Another approach for improving pathological diagnosis involves advanced optical methods such as spectral imaging, which reveals information from the tissue that is beyond human vision. We have recently developed a unique rapid spectral imaging system capable of scanning pathological slides, delivering a wealth of critical diagnostic information. Here, we present a novel application of spectral imaging (SI) for virtual Hematoxylin and Eosin (H&E) staining using a custom-built, rapid Fourier-based SI system. Unstained human biopsy samples are scanned, and a Pix2Pix-based neural network generates realistic H&E-equivalent images. Additionally, we applied Principal Component Analysis (PCA) to the spectral information to examine the effect of down sampling the data on the virtual staining process. To assess model performance, we trained and tested models using full spectral data, RGB, and PCA-reduced spectral inputs. The results demonstrate that PCA-reduced data preserved essential image features while enhancing statistical image quality, as indicated by FID and KID scores, and reducing computational complexity. These findings highlight the potential of integrating SI and AI to enable efficient, accurate, and stain-free digital pathology.
Journal Article
3D-Q-FISH/Telomere/TRF2 Nanotechnology Identifies a Progressively Disturbed Telomere/Shelterin/Lamin AC Complex as the Common Pathogenic, Molecular/Spatial Denominator of Classical Hodgkin Lymphoma
by
Louis, Sherif
,
Mai, Sabine
,
Petrogiannis-Haliotis, Tina
in
3D Q-FISH
,
Analysis
,
B-cell lymphoma
2024
The bi- or multinucleated Reed–Sternberg cell (RS) is the diagnostic cornerstone of Epstein–Barr Virus (EBV)-positive and EBV-negative classical Hodgkin lymphoma (cHL). cHL is a germinal center (GC)-derived B-cell disease. Hodgkin cells (H) are the mononuclear precursors of RS. An experimental model has to fulfill three conditions to qualify as common pathogenic denominator: (i) to be of GC-derived B-cell origin, (ii) to be EBV-negative to avoid EBV latency III expression and (iii) to support permanent EBV-encoded oncogenic latent membrane protein (LMP1) expression upon induction. These conditions are unified in the EBV-, diffuse large B-Cell lymphoma (DLBCL) cell line BJAB-tTA-LMP1. 3D reconstructive nanotechnology revealed spatial, quantitative and qualitative disturbance of telomere/shelterin interactions in mononuclear H-like cells, with further progression during transition to RS-like cells, including progressive complexity of the karyotype with every mitotic cycle, due to BBF (breakage/bridge/fusion) events. The findings of this model were confirmed in diagnostic patient samples and correlate with clinical outcomes. Moreover, in vitro, significant disturbance of the lamin AC/telomere interaction progressively occurred. In summary, our research over the past three decades identified cHL as the first lymphoid malignancy driven by a disturbed telomere/shelterin/lamin AC interaction, generating the diagnostic RS. Our findings may act as trailblazer for tailored therapies in refractory cHL.
Journal Article
Extracellular vesicles from genetically unstable, oncogene-driven cancer cells trigger micronuclei formation in endothelial cells
2020
Oncogenic transformation impacts cancer cell interactions with their stroma, including through formation of abnormal blood vessels. This influence is often attributed to angiogenic growth factors, either soluble, or associated with tumor cell-derived extracellular vesicles (EVs). Here we examine some of the cancer-specific components of EV-mediated tumor-vascular interactions, including the impact of genetic driver mutations and genetic instability. Cancer cells expressing mutant
HRAS
oncogene exhibit aberrations of chromatin architecture, aneuploidy, cytoplasmic chromatin deposition and formation of micronuclei with a non-random chromosome content. EVs released from such
HRAS
-driven cells carry genomic DNA, including oncogenic sequences, and transfer this material to endothelial cells while inducing abnormal formation of micronuclei, along with cell migration and proliferation. Micronuclei were also triggered following treatment with EVs derived from glioma cells (and stem cells) expressing EGFRvIII oncogene, and in both endothelial cells and astrocytes. EVs from HRAS and EGFRvIII-driven cancer cells carry 19 common proteins while EVs from indolent control cells exhibit more divergent proteomes. Immortalized endothelial cell lines with disrupted TP53 pathway were refractory to EV-mediated micronuclei induction. We suggest that oncogenic transformation and intercellular trafficking of cancer-derived EVs may contribute to pathological vascular responses in cancer due to intercellular transmission of genomic instability.
Journal Article