Knockdown of Lamin B1 and the Corresponding Lamin B Receptor Leads to Changes in Heterochromatin State and Senescence Induction in Malignant Melanoma

Werner syndrome RECQ helicase participates in and directs maintenance of the protein complexes of constitutive heterochromatin in proliferating human cells

Werner syndrome of premature aging is caused by mutations in the WRN RECQ helicase/exonuclease, which functions in DNA replication, repair, transcription, and telomere maintenance. How the loss of WRN accelerates aging is not understood in full. Here we show that WRN is necessary for optimal constitutive heterochromatin levels in proliferating human fibroblasts. Locally, WRN deficiency derepresses SATII pericentromeric satellite repeats but does not reduce replication fork progression on SATII repeats. Globally, WRN loss reduces a subset of protein-protein interactions responsible for the organization of constitutive heterochromatin in the nucleus, namely, the interactions involving Lamin B1 and Lamin B receptor, LBR. Both the mRNA level and subcellular distribution of LBR are affected by WRN deficiency, and unlike the former, the latter phenotype does not require WRN catalytic activities. The phenotypes of heterochromatin disruption seen in WRN-deficient proliferating fibroblasts are also observed in WRN-proficient fibroblasts undergoing replicative or oncogene-induced senescence. WRN interacts with histone deacetylase 2, HDAC2; WRN/HDAC2 association is mediated by heterochromatin protein alpha, HP1α, and WRN complexes with HP1α and HDAC2 are downregulated in senescing cells. The data suggest that the effect of WRN loss on heterochromatin is separable from senescence program, but mimics at least some of the heterochromatin changes associated with it.

Mechanism and role of nuclear laminin B1 in cell senescence and malignant tumors

Nuclear lamin B1 (LMNB1) is a member of the nuclear lamin protein family. LMNB1 can maintain and ensure the stability of nuclear structure and influence the process of cell senescence by regulating chromatin distribution, DNA replication and transcription, gene expression, cell cycle, etc. In recent years, several studies have shown that the abnormal expression of LMNB1, a classical biomarker of cell senescence, is highly correlated with the progression of various malignant tumors; LMNB1 is therefore considered a new potential tumor marker and therapeutic target. However, the mechanism of action of LMNB1 is influenced by many factors, which are difficult to clarify at present. This article focuses on the recent progress in understanding the role of LMNB1 in cell senescence and malignant tumors and offers insights that could contribute to elucidating the mechanism of action of LMNB1 to provide a new direction for further research.

Biomarkers of Aging and Relevant Evaluation Techniques: A Comprehensive Review

The risk of developing chronic illnesses and disabilities is increasing with age. To predict and prevent aging, biomarkers relevant to the aging process must be identified. This paper reviews the known molecular, cellular, and physiological biomarkers of aging. Moreover, we discuss the currently available technologies for identifying these biomarkers, and their applications and potential in aging research. We hope that this review will stimulate further research and innovation in this emerging and fast-growing field.

Upregulated expression of lamin B receptor increases cell proliferation and suppresses genomic instability: implications for cellular immortalization

Mammalian somatic cells undergo terminal proliferation arrest after a limited number of cell divisions, a phenomenon termed cellular senescence. However, cells acquire the ability to proliferate infinitely (cellular immortalization) through multiple genetic alterations. Inactivation of tumor suppressor genes such as p53, RB and p16 is important for cellular immortalization, although additional molecular alterations are required for cellular immortalization to occur. Here, we aimed to gain insights into these molecular alterations. Given that cellular immortalization is the escape of cells from cellular senescence, genes that regulate cellular senescence are likely to be involved in cellular immortalization. Because senescent cells show altered heterochromatin organization, we investigated the implications of lamin A/C, lamin B1 and lamin B receptor (LBR), which regulate heterochromatin organization, in cellular immortalization. We employed human immortalized cell lines, KMST-6 and SUSM-1, and found that expression of LBR was upregulated upon cellular immortalization and downregulated upon cellular senescence. In addition, knockdown of LBR induced cellular senescence with altered chromatin configuration. Additionally, enforced expression of LBR increased cell proliferation likely through suppression of genome instability in human primary fibroblasts that expressed the simian virus 40 large T antigen (TAg), which inactivates p53 and RB. Furthermore, expression of TAg or knockdown of p53 led to upregulated LBR expression. These observations suggested that expression of LBR might be upregulated to suppress genome instability in TAg-expressing cells, and, consequently, its upregulated expression assisted the proliferation of TAg-expressing cells (i.e. p53/RB-defective cells). Our findings suggest a crucial role for LBR in the process of cellular immortalization.

Loss of miR-101-3p in melanoma stabilizes genomic integrity, leading to cell death prevention

Malignant melanoma remains the most lethal form of skin cancer, exhibiting poor prognosis after forming distant metastasis. Owing to their potential tumor-suppressive properties by regulating oncogenes and tumor suppressor genes, microRNAs are important player in melanoma development and progression. We defined the loss of miR-101-3p expression in melanoma cells compared with melanocytes and melanoblast-related cells as an early event in tumor development and aimed to understand the tumor suppressive role of miR-101-3p and its regulation of important cellular processes. Reexpression of miR-101-3p resulted in inhibition of proliferation, increase in DNA damage, and induction of apoptosis. We further determined the nuclear structure protein Lamin B1, which influences nuclear processes and heterochromatin structure, ATRX, CASP3, and PARP as an important direct target of miR-101-3p. RNA sequencing and differential gene expression analysis after miR-101-3p reexpression supported our findings and the importance of loss of mir-101-3p for melanoma progression. The validated functional effects are related to genomic instability, as recent studies suggest miRNAs plays a key role in mediating this cellular process. Therefore, we concluded that miR-101-3p reexpression increases the genomic instability, leading to irreversible DNA damage, which leads to apoptosis induction. Our findings suggest that the loss of miR-101-3p in melanoma serves as an early event in melanoma progression by influencing the genomic integrity to maintain the increased bioenergetic demand.

Identification and validation of senescence-related genes in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is an exceedingly intractable issue affecting female endocrine and reproductive health. However, the etiology and intricate pathological mechanisms of PCOS remain unclear. Nowadays, aging was found to share multiple common pathological mechanisms with PCOS, which causes probing into the pathogenesis of PCOS from senescence. However, no bioinformatics analyses have specifically focused on connection between PCOS and ovarian aging.

METHODS

Differentially expressed aging-related genes in PCOS were identified and then analyzed using function enrichment method. Hub genes were determined based on multiple algorithms, and expression validation of hub genes was performed in both datasets and experiments (human granulosa-like tumor cell line, KGN; human Granulosa Cell, hGCs). Finally, a transcription factor-miRNA-gene network of hub genes was constructed.

RESULTS

Here, we identified 73 aging-related differential expression genes (ARDEGs) by intersecting DEGs in PCOS and senescence-related gene set. Furthermore, we performed biological functions and potential pathways of ARDEGs and potential hub genes were also screened by multiple algorithms. From the perspective of immune dysfunction, we analyzed the correlation between PCOS and immune cells. Finally, TF-miRNA-gene networks were constructed. Finally, TF-miRNA-gene networks were constructed.

CONCLUSIONS

Our work aimed to elucidate the relation between PCOS and cellular senescence based on bioinformatics strategy, deepening the understanding of mechanisms and to seek for novel therapy strategies for improving reproductive lifespan and female health. Exploring the potential molecular mechanism of cell aging in PCOS is expected to bring a new breakthrough for PCOS diagnosis and therapy strategies. And this, might deepen our understanding about intricate mechanisms of ovarian aging.

Higher Oxidative Stress in Endometriotic Lesions Upregulates Senescence-Associated p16ink4a and β-Galactosidase in Stromal Cells

Endometriosis affects a significant proportion of women worldwide; however, no definitive cure for this disease has been discovered to date. Oxidative stress promotes endometriotic lesion maintenance in the peritoneal cavity in women. Furthermore, there is evidence of the mitogen-activated protein kinase (MAPK) signaling pathway and senescence involvement in the physiopathogenesis of endometriosis. Reactive oxygen species (ROS) cause oxidative damage and are expected to trigger senescence in the endometrium while also causing alterations in MAPK signaling. However, the role of ROS in the senescence-associated phenotype in endometriosis remains unknown. In this context, this study attempted to delineate the pathways linking ROS to senescence in endometrial and endometriotic lesions of healthy individuals and those with endometriosis. Our results indicate a higher presence of ROS in endometriotic lesions, and the upregulation of MAPK. Furthermore, we show that endometriotic lesions in stromal cells stimulated with hydrogen peroxide develop more senescence traits than eutopic and non-endometriosis endometrium. Overall, endometriotic cells respond differently to extracellular distress. Our contribution to further research in this field contributed to the roadmap of endometriosis' search for alternative treatments.

Current Understanding of the Role of Senescent Melanocytes in Skin Ageing

Melanocytes reside within the basal epidermis of human skin, and function to protect the skin from ultraviolet light through the production of melanin. Prolonged exposure of the skin to UV light can induce irreparable DNA damage and drive cells into senescence, a sustained cell cycle arrest that prevents the propagation of this damage. Senescent cells can also be detrimental and contribute to skin ageing phenotypes through their senescence-associated secretory phenotype. Senescent cells can act in both an autocrine and paracrine manner to produce widespread tissue inflammation and skin ageing. Recently, melanocytes have been identified as the main senescent cell population within the epidermis and have been linked to a variety of skin ageing phenotypes, such as epidermal thinning and the presence of wrinkles. However, the literature surrounding melanocyte senescence is limited and tends to focus on the role of senescence in the prevention of melanoma. Therefore, this review aims to explore the current understanding of the contribution of senescent melanocytes to human skin ageing.

MAGOH and MAGOHB Knockdown in Melanoma Cells Decreases Nonsense-Mediated Decay Activity and Promotes Apoptosis via Upregulation of GADD45A

Cutaneous malignant melanoma is a highly proliferative and aggressive skin cancer with a steadily increasing incidence and a low long-term survival rate after metastatic progression. The protein MAGOH and its highly identical homologue MAGOHB are core components of the exon junction complex (EJC), which regulates splicing, stability and translation of mRNAs. The EJC, and especially MAGOH, has been shown to be involved in the development and progression of several cancers. In melanoma, the expression and function of both homologues remain essentially unexplored. This study identifies high MAGOH and MAGOHB protein expression in cutaneous melanoma cell lines and patient derived tissue samples. An siRNA-mediated knockdown of MAGOH significantly inhibits melanoma cell proliferation. The loss of MAGOH does not affect cell cycle progression, but induces apoptosis, an effect that is enhanced by a simultaneous knockdown of MAGOH and MAGOHB. MAGOH and MAGOHB do not influence the expression of the pro-apoptotic protein Bcl-XS or exon skipping. However, the knockdown of MAGOH and MAGOHB strongly decreases nonsense-mediated decay (NMD) activity, leading to an upregulation of the pro-apoptotic protein GADD45A. In conclusion, simultaneous inhibition of MAGOH and MAGOHB expression substantially affects cell survival, indicating both MAGOH homologues as promising new targets for the treatment of melanoma.

Multilevel view on chromatin architecture alterations in cancer

Chromosomes inside the nucleus are not located in the form of linear molecules. Instead, there is a complex multilevel genome folding that includes nucleosomes packaging, formation of chromatin loops, domains, compartments, and finally, chromosomal territories. Proper spatial organization play an essential role for the correct functioning of the genome, and is therefore dynamically changed during development or disease. Here we discuss how the organization of the cancer cell genome differs from the healthy genome at various levels. A better understanding of how malignization affects genome organization and long-range gene regulation will help to reveal the molecular mechanisms underlying cancer development and evolution.

A Lamin Family-Based Signature Predicts Prognosis and Immunotherapy Response in Hepatocellular Carcinoma

Background. Lamin family members play crucial roles in promoting oncogenesis and cancer development. The values of lamin family in predicting prognosis and immunotherapy response remain largely unclarified. Our research is aimed at comprehensively estimating the clinical significance of lamin family in hepatocellular carcinoma and constructing a novel lamin family-based signature to predict prognosis and guide the precise immunotherapy. Methods. The expression features and prognostic value of LMNA, LMNB1, and LMNB2 were explored in the TCGA and GEO databases. The biological functions of LMNB1 and LMNB2 were validated by in vitro assays. A lamin family-based signature was built using the TCGA training set. The TCGA test set, entire TCGA set, and GSE14520 set were used to validate its predictive power. Univariate and multivariate analyses were performed to evaluate the independence of the lamin family-based signature from other clinicopathological characteristics. A nomogram was constructed using the lamin family-based signature and TNM stage. The associations of this signature with molecular pathways, clinical characteristics, immune cell infiltration, and immunotherapy response were analyzed. Results. Lamin family members were upregulated in HCC. Upregulation of LMNB1 and LMNB2 promoted HCC proliferation, migration, and invasion. The predictive signature was initially established based on LMNB1 and LMNB2 which could effectively identify differences in overall survival, immune cell infiltration, and clinicopathological characteristics of high- and low-risk patients. The nomogram showed high prognostic predictive accuracy. Importantly, the lamin family-based signature was correlated with immune suppression and expression of immune checkpoint molecules. Conclusions. The lamin family-based signature is a robust biomarker to predict overall survival and immunotherapy response in HCC. High-risk score patients have a poorer overall survival and might be more sensitive to immunotherapy. This signature may contribute to improving individualized prognosis prediction and precision immunotherapy for HCC patients.