DNA mismatch repair system: repercussions in cellular homeostasis and relationship with aging

High-Grade Endometrial Cancer: Molecular Subtypes, Current Challenges, and Treatment Options

Although many recent advancements have been made in women's health, perhaps one of the most neglected areas of research is the diagnosis and treatment of high-grade endometrial cancer (EnCa). The molecular classification of EnCa in concert with histology was a major step forward. The integration of profiling for mismatch repair deficiency and Human Epidermal Growth Factor 2 (HER2) overexpression, can further inform treatment options, especially for drug resistant recurrent disease. Recent early phase trials suggest that regardless of subtype, combination therapy with agents that have distinct mechanisms of action is a fruitful approach to the treatment of high-grade EnCa. Unfortunately, although the importance of diagnosis and treatment of high-grade EnCa is well recognized, it is understudied compared to other gynecologic and breast cancers. There remains a tremendous need to couple molecular profiling and biomarker development with promising treatment options to inform new treatment strategies with higher efficacy and safety for all who suffer from high-grade recurrent EnCa.

Cellular rejuvenation: molecular mechanisms and potential therapeutic interventions for diseases

The ageing process is a systemic decline from cellular dysfunction to organ degeneration, with more predisposition to deteriorated disorders. Rejuvenation refers to giving aged cells or organisms more youthful characteristics through various techniques, such as cellular reprogramming and epigenetic regulation. The great leaps in cellular rejuvenation prove that ageing is not a one-way street, and many rejuvenative interventions have emerged to delay and even reverse the ageing process. Defining the mechanism by which roadblocks and signaling inputs influence complex ageing programs is essential for understanding and developing rejuvenative strategies. Here, we discuss the intrinsic and extrinsic factors that counteract cell rejuvenation, and the targeted cells and core mechanisms involved in this process. Then, we critically summarize the latest advances in state-of-art strategies of cellular rejuvenation. Various rejuvenation methods also provide insights for treating specific ageing-related diseases, including cellular reprogramming, the removal of senescence cells (SCs) and suppression of senescence-associated secretory phenotype (SASP), metabolic manipulation, stem cells-associated therapy, dietary restriction, immune rejuvenation and heterochronic transplantation, etc. The potential applications of rejuvenation therapy also extend to cancer treatment. Finally, we analyze in detail the therapeutic opportunities and challenges of rejuvenation technology. Deciphering rejuvenation interventions will provide further insights into anti-ageing and ageing-related disease treatment in clinical settings.

Understanding the Impact of Obesity on Ageing in the Radiance of DNA Metabolism

Ageing is a multi-factorial phenomenon which is considered as a major risk factor for the development of neurodegeneration, osteoporosis, cardiovascular disease, dementia, cancer, and other chronic diseases. Phenotypically, ageing is related with a combination of molecular, cellular, and physiological levels like genomic and epi-genomic alterations, loss of proteostasis, deregulation of cellular and subcellular function and mitochondrial dysfunction. Though, no single molecular mechanism accounts for the functional decline of different organ systems in older humans but accumulation of DNA damage or mutations is a dominant theory which contributes largely to the development of ageing and age-related diseases. However, mechanistic, and hierarchical order of these features of ageing has not been clarified yet. Scientific community now focus on the effect of obesity on accelerated ageing process. Obesity is a complex chronic disease that affects multiple organs and tissues. It can not only lead to various health conditions such as diabetes, cancer, and cardiovascular disease but also can decrease life expectancy which shows similar phenotype of ageing. Higher loads of DNA damage were also observed in the genome of obese people. Thus, inability of DNA damage repair may contribute to both ageing and obesity apart from cancer predisposition. The present review emphasizes on the involvement of molecular phenomenon of DNA metabolism in development of obesity and how it accelerates ageing in mammals.

Challenges of proving a causal role of somatic mutations in the aging process

Aging is accompanied by the progressive accumulation of permanent changes to the genomic sequence, termed somatic mutations. Small mutations, including single‐base substitutions and insertions/deletions, are key determinants of the malignant transformations leading to cancer, but their role as initiators of other age‐related phenotypes is controversial. Here, we present recent advances in the study of somatic mutagenesis in aging tissues and posit that the current uncertainty about its causal effects in the aging process is due to technological and methodological weaknesses. We highlight classical and novel experimental systems, including premature aging syndromes, that could be used to model the increase of somatic mutation burden and understand its functional role. It is important that studies are designed to take into account the biological context and peculiarities of each tissue and that the downstream impact of somatic mutation accumulation is measured by methods able to resolve subtle cellular changes.

Role of mismatch repair in aging

A common feature of aging is the accumulation of genetic damage throughout life. DNA damage can lead to genomic instability. Many diseases associated with premature aging are a result of increased accumulation of DNA damage. In order to minimize these damages, organisms have evolved a complex network of DNA repair mechanisms, including mismatch repair (MMR). In this review, we detail the effects of MMR on genomic instability and its role in aging emphasizing on the association between MMR and the other hallmarks of aging, serving to drive or amplify these mechanisms. These hallmarks include telomere attrition, epigenetic alterations, mitochondrial dysfunction, altered nutrient sensing and cell senescence. The close relationship between MMR and these markers may provide prevention and treatment strategies, to reduce the incidence of age-related diseases and promote the healthy aging of human beings.

Differential sensitivity of renal carcinoma cells to doxorubicin and epigenetic therapeutics depends on the genetic background

Differential sensitivity to chemotherapeutics is a limitation in chemotherapy of kidney cancer patients. Role of genetic background in chemotherapy is not fully understood. Therefore, this study evaluated the influence of genetic/epigenetic background of renal cancer cells on the sensitivity to chemotherapeutics. Two renal cell carcinoma (RCC) cell lines, Caki-1 and 786-0, with different genetic makeup of p53 and VHL were treated with doxorubicin either alone or in combination with epigenetic therapeutics 5-aza-2-dc and TSA. Sensitivity of RCC cells to these drugs was evaluated by cell viability and cell cycle analysis and was further confirmed by analysis of selected genes expression. Cell viability data revealed that 786-0 cells were more sensitive than Caki-1 to doxorubicin. Combination of doxorubicin with 5-aza-2-dc or TSA was more effective to inhibit growth of Caki-1 cells but not the 786-0. Data of cell cycle analysis and expression of representative genes for tumor suppressor, cell cycle and survival, drug transporter and DNA repair further provided the molecular basis for differential sensitivity of Caki-1 and 786-0 cell lines to doxorubicin. Important findings of this study suggest that doxorubicin is more cytotoxic to primary renal cancer 786-0 cells with mutant VHL and p53 than the metastatic Caki-1 cells with wild-type VHL and p53, and this differential response was independent of p53 expression level. This study suggests that combination of doxorubicin with epigenetic therapeutics could potentially be beneficial in clinical treatment of renal cancer patients with wild-type VHL and p53 but not in patients with mutant VHL and p53.

Comprehensive Profiling of Proteome and Ubiquitome Changes in Human Lens Epithelial Cell Line after Ultraviolet-B Irradiation

Ultraviolet-B (UVB) is a recognized risk factor for age-related cataract (ARC) and can cause various changes, including ubiquitination, in lens epithelial cells (LECs). However, the relationship between ubiquitination and ARC is unclear. Herein, we used UVB-irradiated human lens epithelial cell line (SRA01/04) representing the cell model of ARC to investigate the profile changes in the proteome and ubiquitome. A total of 552 differentially expressed proteins (DEPs) and 871 differentially ubiquitinated proteins (DUPs) were identified, and 9 ubiquitination motifs were found. Bioinformatics analysis revealed diverse pathways and biological processes of differential proteins and several DNA damage repair proteins that were potentially mediated via ubiquitin-proteasome pathway. We validated the decreased protein expression of DNA-directed RNA polymerase II subunit RPB2 (POLR2B) in both human cataract capsule tissues and UVB-treated SRA01/04 cells and found that treatment with proteasome inhibitor (MG-132) could reverse the protein level of POLR2B in UVB-irradiated SRA01/04 cells. Our data provide novel information regarding protein expressions and ubiquitination modifications in UVB-induced oxidative damage model. This study might offer a cell-level reference to further investigate the pathogenesis of ARC.

Transcriptional Profiles of Skeletal Muscle Associated With Increasing Severity of White Striping in Commercial Broilers

Development of the white striping (WS) abnormality adversely impacts overall quality of broiler breast meat. Its etiology remains unclear. This study aimed at exploring transcriptional profiles of broiler skeletal muscles exhibiting different WS severity to elucidate molecular mechanisms underlying the development and progression of WS. Total RNA was isolated from pectoralis major of male 7-week-old Ross 308 broilers. The samples were classified as mild (n = 6), moderate (n = 6), or severe (n = 4), based on number and thickness of the white striations on the meat surface. The transcriptome was profiled using a chicken gene expression microarray with one-color hybridization technique. Gene expression patterns of each WS severity level were compared against each other; hence, there were three comparisons: moderate vs. mild (C1), severe vs. moderate (C2), and severe vs. mild (C3). Differentially expressed genes (DEGs) were identified using the combined criteria of false discovery rate ≤ 0.05 and absolute fold change ≥1.2. Differential expression of 91, 136, and 294 transcripts were identified in C1, C2, and C3, respectively. There were no DEGs in common among the three comparisons. Based on pathway analysis, the enriched pathways of C1 were related with impaired homeostasis of macronutrients and small biochemical molecules with disrupted Ca²⁺-related pathways. Decreased abundance of the period circadian regulator suggested the shifted circadian phase when moderate WS developed. The enriched pathways uniquely obtained in C2 were RNA degradation, Ras signaling, cellular senescence, axon guidance, and salivary secretion. The DEGs identified in those pathways might play crucial roles in regulating cellular ion balances and cell-cycle arrest. In C3, the pathways responsible for phosphatidylinositol 3-kinase-Akt signaling, p53 activation, apoptosis, and hypoxia-induced processes were modified. Additionally, pathways associated with a variety of diseases with the DEGs involved in regulation of [Ca²⁺], collagen formation, microtubule-based motor, and immune response were identified. Eight pathways were common to all three comparisons (i.e., calcium signaling, Ras-associated protein 1 signaling, ubiquitin-mediated proteolysis, vascular smooth muscle contraction, oxytocin signaling, and pathway in cancer). The current findings support the role of intracellular ion imbalance, particularly Ca²⁺, oxidative stress, and impaired programmed cell death on WS progression.

Hypoxia-Inducible Histone Lysine Demethylases: Impact on the Aging Process and Age-Related Diseases

Hypoxia is an environmental stress at high altitude and underground conditions but it is also present in many chronic age-related diseases, where blood flow into tissues is impaired. The oxygen-sensing system stimulates gene expression protecting tissues against hypoxic insults. Hypoxia stabilizes the expression of hypoxia-inducible transcription factor-1α (HIF-1α), which controls the expression of hundreds of survival genes related to e.g. enhanced energy metabolism and autophagy. Moreover, many stress-related signaling mechanisms, such as oxidative stress and energy metabolic disturbances, as well as the signaling cascades via ceramide, mTOR, NF-κB, and TGF-β pathways, can also induce the expression of HIF-1α protein to facilitate cell survival in normoxia. Hypoxia is linked to prominent epigenetic changes in chromatin landscape. Screening studies have indicated that the stabilization of HIF-1α increases the expression of distinct histone lysine demethylases (KDM). HIF-1α stimulates the expression of KDM3A, KDM4B, KDM4C, and KDM6B, which enhance gene transcription by demethylating H3K9 and H3K27 sites (repressive epigenetic marks). In addition, HIF-1α induces the expression of KDM2B and KDM5B, which repress transcription by demethylating H3K4me2,3 sites (activating marks). Hypoxia-inducible KDMs support locally the gene transcription induced by HIF-1α, although they can also control genome-wide chromatin landscape, especially KDMs which demethylate H3K9 and H3K27 sites. These epigenetic marks have important role in the control of heterochromatin segments and 3D folding of chromosomes, as well as the genetic loci regulating cell type commitment, proliferation, and cellular senescence, e.g. the INK4 box. A chronic stimulation of HIF-1α can provoke tissue fibrosis and cellular senescence, which both are increasingly present with aging and age-related diseases. We will review the regulation of HIF-1α-dependent induction of KDMs and clarify their role in pathological processes emphasizing that long-term stress-related insults can impair the maintenance of chromatin landscape and provoke cellular senescence and tissue fibrosis associated with aging and age-related diseases.

Mismatch repair system in endometriotic tissue and eutopic endometrium of unaffected women

OBJECTIVE

To test the immunohistochemical staining pattern of some mismatch repair (MMR) system proteins in endometriotic tissue (ET) and eutopic endometrium.

METHODS

This was a retrospective study conducted at the Pathology and Obstetrics and Gynecology Departments of the Udine University Hospital. We analyzed 528 samples obtained from 246 patients affected by endometriosis and 71 samples from 71 patients with normal endometrium. A tissue microarray model was used to analyze the immunohistochemical expression of MMR system proteins.

RESULTS

Significant loss of MMR proteins was found in the stromal component of ETs. We found MSH2 to be expressed at a higher level than any other MMR system proteins in eutopic endometrium and ETs, to be significantly correlated to Ki-67 expression in both stromal and glandular components of ETs, and to be expressed at a significantly higher level in ETs than in eutopic endometrium. When considering the subgroup of endometriosis with high recurrence rate and glandular cytoplasmic staining for aurora A kinase, we found MMR proteins expressed at a significantly higher level in these ETs than in other ETs and eutopic endometrium of unaffected women.

CONCLUSIONS

We found significant loss of MMR proteins (known to be associated with microsatellite instability) in the stromal component of ETs. The group of ETs with glandular cytoplasmic staining for aurora A kinase had higher MMR protein expression, suggesting an increased activity of this system. Our result suggests a novel role of increased MSH2 expression in cellular proliferation of endometriosis.

BMI‑1 is important in bufalin‑induced apoptosis of K562 cells

The purpose of this study was to analyze the effects of bufalin on the gene expression of K562 cells and on the expression of BMI‑1 pathway constituents in K562 cell apoptosis. K562 cells were treated with bufalin, and the inhibition rate and apoptosis were detected by an MTT assay, flow cytometry and a microarray assay. BMI‑1, p16INK4a and p14ARF were examined by quantitative polymerase chain reaction (qPCR). Bufalin induced significant changes in the gene expression of the K562 cells; 4296 genes were differentially expressed, 2185 were upregulated and 2111 were downregulated. The most upregulated genes were associated with transcription regulation, while the most downregulated genes were associated with the non-coding RNA metabolic processes and DNA repair. qPCR analysis demonstrated that BMI‑1 was overexpressed in the K562 cells. Bufalin is able to downregulate BMI‑1 expression levels in K562 cells prematurely and cause an increase in the expression levels of p16INK4a and p14ARF. Moreover, bufalin downregulated BCR/ABL expression levels in a time‑dependent manner, and the expression of BCR/ABL was not associated with the upregulation or downregulation of BMI‑1 expression. Bufalin may induce K562 cell apoptosis by downregulating BMI‑1 expression levels and accordingly upregulating the expression levels of p16INK4a and p14ARF. Bufalin may also induce K562 cell apoptosis via downregulating BCR/ABL expression levels, and this pathway may be independent of the BMI‑1 pathway.

Parkinson's disease: a complex interplay of mitochondrial DNA alterations and oxidative stress

Parkinson’s disease (PD) is one of the most common age-related neurodegenerative diseases. This pathology causes a significant loss of dopaminergic neurons in the Substantia Nigra. Several reports have claimed a role of defective nuclear and mitochondrial DNA repair pathways in PD etiology, in particular, of the Base Excision Repair (BER) system. In addition, recent findings, related to PD progression, indicate that oxidative stress pathways involving c-Abl and GST could also be implicated in this pathology. This review focuses on recently described networks most likely involved in an integrated manner in the course of PD.