SIRT1-SIRT7 Expression in Patients with Lymphoproliferative Disorders Undergoing Hematopoietic Stem Cell Mobilization

Sirtuins Affect Cancer Stem Cells via Epigenetic Regulation of Autophagy

Sirtuins (SIRTs) are stress-responsive proteins that regulate several post-translational modifications, partly by acetylation, deacetylation, and affecting DNA methylation. As a result, they significantly regulate several cellular processes. In essence, they prolong lifespan and control the occurrence of spontaneous tumor growth. Members of the SIRT family have the ability to govern embryonic, hematopoietic, and other adult stem cells in certain tissues and cell types in distinct ways. Likewise, they can have both pro-tumor and anti-tumor effects on cancer stem cells, contingent upon the specific tissue from which they originate. The impact of autophagy on cancer stem cells, which varies depending on the specific circumstances, is a very intricate phenomenon that has significant significance for clinical and therapeutic purposes. SIRTs exert an impact on the autophagy process, whereas autophagy reciprocally affects the activity of certain SIRTs. The mechanism behind this connection in cancer stem cells remains poorly understood. This review presents the latest findings that position SIRTs at the point where cancer cells and autophagy interact. Our objective is to highlight the various roles of distinct SIRTs in cancer stem cell-related functions through autophagy. This would demonstrate their significance in the genesis and recurrence of cancer and offer a more precise understanding of their treatment possibilities in relation to autophagy.

SIRT7: the seventh key to unlocking the mystery of aging

Aging is a chronic yet natural physiological decline of the body. Throughout life, humans are continuously exposed to a variety of exogenous and endogenous stresses, which engender various counteractive responses at the cellular, tissue, organ, as well as organismal levels. The compromised cellular and tissue functions that occur because of genetic factors or prolonged stress (or even the stress response) may accelerate aging. Over the last two decades, the sirtuin (SIRT) family of lysine deacylases has emerged as a key regulator of longevity in a variety of organisms. SIRT7, the most recently identified member of the SIRTs, maintains physiological homeostasis and provides protection against aging by functioning as a watchdog of genomic integrity, a dynamic sensor and modulator of stresses. SIRT7 decline disrupts metabolic homeostasis, accelerates aging, and increases the risk of age-related pathologies including cardiovascular and neurodegenerative diseases, pulmonary and renal disorders, inflammatory diseases, and cancer, etc. Here, we present SIRT7 as the seventh key to unlock the mystery of aging, and its specific manipulation holds great potential to ensure healthiness and longevity.

Ginsenoside Rh4 inhibits the malignant progression of multiple myeloma and induces ferroptosis by regulating SIRT2

Multiple myeloma (MM) has a high mortality rate, and the exploration of therapeutic drugs for MM with low side effects is a hot topic at the moment. Ginsenoside Rh4 has been shown to inhibit tumour growth in many cancers. However, the role of ginsenoside Rh4 in MM and its reaction mechanism have not been reported so far. After the treatment with different concentrations of ginsenoside Rh4, the proliferation of NCI-H929 cells was detected by Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine staining. The cell apoptosis and cycle arrest were detected by flow cytometry and western blot. The thiobarbituric acid-reactive substances (TBARS) production was assessed with TBARS assay, whereas Fe²⁺ fluorescence assay was used for the measurement of Fe²⁺ level. The production of reactive oxygen species was evaluated with dichloro-dihydro-fluorescein diacetate staining, and western blot was applied for the estimation of ferroptosis-related proteins. The potential targets of ginsenoside Rh4 were predicted by molecular docking technology and verified by western blot. The transfection efficacy of overexpression-SIRT2 was examined with quantitative reverse transcription polymerase chain reaction and western blot. To figure out the detailed reaction mechanism between ginsenoside Rh4 and SIRT2 in MM, rescue experiments were conducted. We found that ginsenoside Rh4 inhibited cell proliferation, induced cell apoptosis, promoted cycle arrest and facilitated ferroptosis in MM. Moreover, ginsenoside Rh4 inhibited SIRT2 expression in MM cells. The overexpression of SIRT2 reversed the effects of ginsenoside Rh4 on cell proliferation, cell apoptosis, cycle arrest and ferroptosis in MM. Overall, ginsenoside Rh4 inhibited the malignant progression of MM and induced ferroptosis by regulating SIRT2.

α-Viniferin-Induced Apoptosis through Downregulation of SIRT1 in Non-Small Cell Lung Cancer Cells

α-Viniferin, a natural stilbene compound found in plants and a polymer of resveratrol, had demonstrated potential anti-cancer and anti-inflammatory effects. However, the specific mechanisms underlying its anti-cancer activity were not yet fully understood and required further investigation. This study evaluated the effectiveness of α-viniferin and ε-viniferin using MTT assay. Results showed that α-viniferin was more effective than ε-viniferin in reducing the viability of NCI-H460 cells, a type of non-small cell lung cancer. Annexin V/7AAD assay results provided further evidence that the decrease in cell viability observed in response to α-viniferin treatment was due to the induction of apoptosis in NCI-H460 cells. The present findings indicated that treatment with α-viniferin could stimulate apoptosis in cells by cleaving caspase 3 and PARP. Moreover, the treatment reduced the expression of SIRT1, vimentin, and phosphorylated AKT, and also induced AIF nuclear translocation. Furthermore, this research provided additional evidence for the effectiveness of α-viniferin as an anti-tumor agent in nude mice with NCI-H460 cell xenografts. As demonstrated by the TUNEL assay results, α-viniferin promoted apoptosis in NCI-H460 cells in nude mice.

Inflammation-related mRNA expression in patients with multiple myeloma undergoing hematopoietic stem cell mobilization

Mobilization of CD34+ cells is a key element in the therapy of patients with multiple myeloma undergoing autologous stem cell transplantation. The use of chemotherapy and the granulocyte colony-stimulating factor can significantly affect the expression of inflammation-related proteins and the migration of hematopoietic stem cells. We assessed the mRNA expression of selected proteins involved in the inflammatory landscape in MM patients (n=71). The aim of the study was to evaluate C-C motif chemokine ligand 3, 4, 5 (CCL3, CCL4, CCL5), leukocyte cell-derived chemotaxin 2 (LECT2), tumor necrosis factor (TNF), and formyl peptide receptor 2 (FPR2) levels in the course of mobilization and their role in the CD34+ collection efficacy. mRNA expression from peripheral blood plasma was evaluated by RT-PCR. We observed a deep decline in CCL3, CCL4, LECT2, and TNF mRNA expression on the day of the first apheresis (day A) as compared to baseline. A negative correlation was observed between CCL3, FPR2, LECT2, TNF level, and the CD34+ cells count in peripheral blood on day A, and the number of CD34+ cells obtained at first apheresis . Our results indicate that the investigated mRNAs significantly alter and may regulate the migration of CD34+ cells during mobilization. Moreover, in case of FPR2 and LECT2, the results obtained in patients differ from the murine models.

Anoxia Rapidly Induces Changes in Expression of a Large and Diverse Set of Genes in Endothelial Cells

Sinusoidal endothelial cells are the predominant vascular surface of the bone marrow and constitute the functional hematopoietic niche where hematopoietic stem and progenitor cells receive cues for self-renewal, survival, and differentiation. In the bone marrow hematopoietic niche, the oxygen tension is usually very low, and this condition affects stem and progenitor cell proliferation and differentiation and other important functions of this region. Here, we have investigated in vitro the response of endothelial cells to a marked decrease in O2 partial pressure to understand how the basal gene expression of some relevant biological factors (i.e., chemokines and interleukins) that are fundamental for the intercellular communication could change in anoxic conditions. Interestingly, mRNA levels of CXCL3, CXCL5, and IL-34 genes are upregulated after anoxia exposure but become downmodulated by sirtuin 6 (SIRT6) overexpression. Indeed, the expression levels of some other genes (such as Leukemia Inhibitory Factor (LIF)) that were not significantly affected by 8 h anoxia exposure become upregulated in the presence of SIRT6. Therefore, SIRT6 mediates also the endothelial cellular response through the modulation of selected genes in an extreme hypoxic condition.

The mitochondrial unfolded protein response: A multitasking giant in the fight against human diseases

Mitochondria, which serve as the energy factories of cells, are involved in cell differentiation, calcium homeostasis, amino acid and fatty acid metabolism and apoptosis. In response to environmental stresses, mitochondrial homeostasis is regulated at both the organelle and molecular levels to effectively maintain the number and function of mitochondria. The mitochondrial unfolded protein response (UPR^mt) is an adaptive intracellular stress mechanism that responds to stress signals by promoting the transcription of genes encoding mitochondrial chaperones and proteases. The mechanism of the UPR^mt in Caenorhabditis elegans (C. elegans) has been clarified over time, and the main regulatory factors include ATFS-1, UBL-5 and DVE-1. In mammals, the activation of the UPR^mt involves eIF2α phosphorylation and the uORF-regulated expression of CHOP, ATF4 and ATF5. Several additional factors, such as SIRT3 and HSF1, are also involved in regulating the UPR^mt. A deep and comprehensive exploration of the UPR^mt can provide new directions and strategies for the treatment of human diseases, including aging, neurodegenerative diseases, cardiovascular diseases and diabetes. In this review, we mainly discuss the function of UPR^mt, describe the regulatory mechanisms of UPR^mt in C. elegans and mammals, and summarize the relationship between UPR^mt and various human diseases.