Sirtuin 2 promotes cell stemness and MEK/ERK signaling pathway while reduces chemosensitivity in endometrial cancer

Immune microenvironment and molecular mechanisms in endometrial cancer: implications for resistance and innovative treatments

This review provides a systematic overview of the molecular mechanisms of endometrial cancer and its drug resistance, particularly involving the aberrant activation of some key signaling pathways. These molecular mechanisms significantly affect the therapeutic outcome of endometrial cancer by promoting tumor cell proliferation, anti-apoptosis, and drug resistance. The article also analyzes the critical role of the immune microenvironment in cancer drug resistance, focusing on the impact of immune cells, immune checkpoints, and hypoxic metabolic reprogramming on anticancer therapies. In recent years, immunotherapy and individualized therapy have shown promising clinical outcomes, especially in advanced endometrial cancer. This article summarizes recent advances in related therapeutic strategies and proposes emerging therapeutic strategies by targeting key pathways and modulating the immune microenvironment to overcome drug resistance and improve patient prognosis.

Emerging roles of mitochondrial sirtuin SIRT5 in succinylation modification and cancer development

Succinylation represents an emerging class of post-translational modifications (PTMs), characterized by the enzymatic or non-enzymatic transfer of a negatively charged four-carbon succinyl group to the ϵ-amino group of lysine residues, mediated by succinyl-coenzyme A. Recent studies have highlighted the involvement of succinylation in various diseases, particularly cancer progression. Sirtuin 5 (SIRT5), a member of the sirtuin family, has been extensively studied for its robust desuccinylase activity, alongside its deacetylase function. To date, only a limited number of SIRT5 substrates have been identified. These substrates mediate diverse physiological processes such as glucose oxidation, fatty acid oxidation, ammonia detoxification, reactive oxygen species scavenging, anti-apoptosis, and inflammatory responses. The regulation of these activities can occur through either the same enzymatic activity acting on different substrates or distinct enzymatic activities targeting the same substrate. Aberrant expression of SIRT5 has been closely linked to tumorigenesis and disease progression; however, its role remains controversial. SIRT5 exhibits dual functionalities: it can promote tumor proliferation, metastasis, drug resistance, and metabolic reprogramming, thereby acting as an oncogene; conversely, it can also inhibit tumor cell growth and induce apoptosis, functioning as a tumor suppressor gene. This review aims to provide a comprehensive overview of the current research status of SIRT5. We discuss its structural characteristics and regulatory mechanisms, compare its functions with other sirtuin family members, and elucidate the mechanisms regulating SIRT5 activity. Specifically, we focus on the role of succinylation modification mediated by SIRT5 in tumor progression, highlighting how desuccinylation by SIRT5 modulates tumor development and delineating the underlying mechanisms involved.

MicroRNA-34a negatively regulates Netrin1 and mediates MEK/ERK pathway to regulate chemosensitivity of gastric cancer cells

OBJECTIVE

To explore the mechanism of action of MicroRNAs-34a (miR-34a) and Eurite growth guiding factor 1 (Netrin1) in cisplatin resistance in gastric cancer (GC), providing new clues for overcoming tumor resistance and optimizing anti-tumor therapy for GC.

METHODS

The Cancer Genome Atlas (TCGA), Differentially Expressed MicroRNAs (miRNAs) in human cancers (dbDEMC), and Starbase online databases were used to analyze the correlation between miR-34a and Netrin-1 and prognosis in GC, and to predict and verify the targeted binding of miR-34a to Netrin-1. The experimental methods including Cell transfection, real-time polymerase chain reaction (RT-PCR), Cell-Counting-Kit-8 (CCK8) assay, flow cytometry, wound scratch assay, transwell assay, and western blotting were used to investigate the effects of miR-34a and Netrin1 on chemotherapy resistance and biological characteristics in cisplatin-resistant GC cells (HGC27/DDP), and to analyze the molecular mechanism of cisplatin resistance.

RESULTS

miR-34a expression was downregulated in gastric cancer clinical samples and cisplatin-resistant cells, while Netrin1 was upregulated, and was related to overall survival (OS). Upregulation of miR-34a can significantly reduce the IC50 value of cisplatin(0.65 vs 1.6 ng/mL) and Multidrug Resistance 1 (MDR-1) protein level, inhibit the proliferation activity, reduce the expression levels of proliferating cell nuclear antigen (PCNA) and ki-67 protein, and induce the increase of apoptosis rate and the enhancement of cycle arrest. Upregulation of miR-34a can also significantly reduce the expression level of Matrix metalloproteinase 9 (MMP9) protein, promote the expression of E-cadherin protein, reduce the wound healing rate and invasion number to inhibit migration and invasion ability in drug-resistant gastric cancer cells. Moreover, overexpression of Netrin1 on the basis of upregulation of miR-34a can weaken the above changes caused by upregulation of miR-34a. In addition, upregulation of miR-34a can significantly inhibit the Mitogen-activated protein kinase kinase (MEK) / Extracellular regulated protein kinases (ERK) pathway, while overexpression of Netrin1 can activate the MEK/ERK pathway, and inhibition of MEK/ERK pathway can effectively counteract the protein expression of Netrin1, and reverse changes in the expression of cisplatin IC50 and MDR-1 proteins caused by co-upregulation of miR-34a/Netrin1 in HGC27/DDP, as well as changes in proliferation, apoptosis, migration and invasion. In addition, upregulation of miR-34a can significantly inhibit the MEK/ERK pathway, while overexpression of Netrin1 can activate the MEK/ERK pathway. If the MEK/ERK pathway was inhibited, it can effectively counteract the protein overexpression of Netrin1, and reverse the changes in the expression of cisplatin IC50 and MDR-1 proteins in HGC27/DDP induced by co-upregulation of miR-34a / Netrin1, as well as changes in proliferation, apoptosis, migration and invasion.

CONCLUSION

miR-34a targets and negatively regulates Netrin1 to mediate the proliferation, apoptosis, apoptosis, migration, and invasion of drug-resistant gastric cancer cells via the MEK/ERK pathway, and change the chemosensitivity in GC cells. miR-34a/Netrin1/MEK/ERK axis may serve as a novel therapeutic target for chemoresistance in GC, it is of great significance for overcoming drug resistance and developing new therapeutic strategies for GC.

Selective inhibition of SIRT2: A disputable therapeutic approach in cancer therapy

Sirtuin 2 (SIRT2) is involved in a wide range of processes, from transcription to metabolism to genome stability. Dysregulation of SIRT2 has been associated with the pathogenesis and progression of different diseases, such as cancer and neurodegenerative disorders. In this context, targeting SIRT2 activity by small molecule inhibitors is a promising therapeutic strategy for treating related conditions, particularly cancer. This review summarizes the regulatory roles and molecular mechanisms of SIRT2 in cancer and the attempts to evaluate potential antitumor activities of SIRT2-selective inhibitors by in vitro and in vivo testing, which are expected to deepen our understanding of the role of SIRT2 in tumorigenesis and progression and may offer important clues or inspiration ideas for developing SIRT2 inhibitors with excellent affinity and selectivity.

Label-free quantitative proteomic analyses of mouse astrocytes provides insight into the host response mechanism at different developmental stages of Toxoplasma gondii

Toxoplasma gondii (T. gondii) is an opportunistic parasite that can infect the central nervous system (CNS), causing severe toxoplasmosis and behavioral cognitive impairment. Mortality is high in immunocompromised individuals with toxoplasmosis, most commonly due to reactivation of infection in the CNS. There are still no effective vaccines and drugs for the prevention and treatment of toxoplasmosis. There are five developmental stages for T. gondii to complete life cycle, of which the tachyzoite and bradyzoite stages are the key to the acute and chronic infection. In this study, to better understanding of how T. gondii interacts with the host CNS at different stages of infection, we constructed acute and chronic infection models of T. gondii in astrocytes, and used label-free proteomics to detect the proteome changes before and after infection, respectively. A total of 4676 proteins were identified, among which 163 differentially expressed proteins (fold change ≥ 1.5 or ≤ 0.67 and p-value ≤ 0.05) including 109 up-regulated proteins and 54 down-regulated proteins in C8-TA vs C8 group, and 719 differentially expressed proteins including 495 up-regulated proteins and 224 down-regulated proteins in C8-BR vs C8-TA group. After T. gondii tachyzoites infected astrocytes, differentially expressed proteins were enriched in immune-related biological processes to promote the formation of bradyzoites and maintain the balance of T. gondii, CNS and brain. After T. gondii bradyzoites infected astrocytes, the differentially expressed proteins up-regulated the host's glucose metabolism, and some up-regulated proteins were strongly associated with neurodegenerative diseases. These findings not only provide new insights into the psychiatric pathogenesis of T. gondii, but also provide potential targets for the treatment of acute and chronic Toxoplasmosis.

Prognostic value of sirtuin family members and experimental verification identify SIRT5 as diagnostic biomarkers in clear cell renal cell carcinoma

BACKGROUND

The sirtuins (SIRTs) family is a nicotinamide adenine dinucleotide (NAD+) family of dependent deacetylases, which includes SIRT1-7. This family is related to the development and progression of various tumors. However, a comprehensive analysis of the role of SIRTs in clear cell renal cell carcinoma (ccRCC) is still lacking, and there are few reports on the inhibitory role of SIRT5 in ccRCC.

METHODS

We used immunohistochemical analysis, and several bioinformatic databases to perform an integrated analysis of the expression and prognostic value of SIRT5 and other SIRT family members in ccRCC along with the associated immune cell infiltration. These databases include TIMER, THPA, cell culture, UALCAN, cBioPortal, WebGestalt, Metascape, DiseaseMeth, STRING database, and Cytoscape.

RESULTS

The protein expression of SIRT1, 2, 3, 6, and 7 were upregulated in ccRCC for the Human Protein Atlas database, whereas the expression of SIRT4 and SIRT5 was decreased. The expression based on tumor stage, and grade followed a similar trend. Kaplan-Meier analysis showed that high SIRT4 and SIRT5 expression was positively related to better overall survival (OS), whereas SIRT6 and SIRT7 expression was positively related to worse OS. Further, high SIRT3 expression was related to worse relapse-free survival (RFS), whereas high SIRT5 expression was related to better RFS. To explore the mechanism underlying the function of SIRTs in ccRCC, we also used several databases to perform the functional enrichment analysis and explore the relationship between infiltrating immune cells and seven SIRT family members in ccRCC. The results showed that several SIRT family members, and particularly SIRT5, are correlated with the infiltration of some important immune cells. The protein expression of SIRT5 was significantly lower in tumor tissue compared to normal tissue and was negatively related to the age of the patient ccRCC individual tumor stages, and grades. In human ccRCC samples, strong IHC staining expression of SIRT5 was displayed in adjacent normal tissue than in tumor tissues.

CONCLUSION

SIRT5 may be a prognostic marker and a novel strategy for the treatment of ccRCC.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

PCDH7 knockdown potentiates colon cancer cells to chemotherapy via inducing ferroptosis and changes in autophagy through restraining MEK1/2/ERK/c-Fos axis

Chemotherapy is a commonly utilized treatment strategy for colon cancer, a prevalent malignancy. The study intends to probe the function and mechanism of protocadherin 7 (PCDH7) in colon cancer. Gain or loss of functional assays of PCDH7 was performed. MTT and colony formation assay monitored cell proliferation. Transwell measured migration and invasion. Real-time quantitative polymerase chain reaction and western blot verified the profiles of PCDH7 and the MEK1/2/ERK/c-FOS pathway. Western blot was implemented to confirm the profiles of PP1α, MLC2, and p-MLC2 for evaluating the impact of PCDH7 on homotypic cells in cell (hocic) structures. Further, an in-vivo nude mouse model was engineered to figure out the function and mechanism of PCDH7 in tumor cell growth. As indicated by the data, PCDH7 knockdown boosted the cells' sensitivity to chemotherapy. PCDH7 overexpression facilitated their proliferation and invasion, altered autophagy, induced ferroptosis and hocic, and initiated the profile of the MEK1/2/ERK/c-FOS pathway. MEK1/2/ERK inhibition impaired the inhibitory impact of PCDH7 on colon cancer cells' chemotherapy sensitivity and dampened its pro-cancer function in the cells. In-vivo experiments displayed that PCDH7 overexpression stepped up tumor growth and pulmonary metastasis in colon cancer cells. All in all, the research has discovered that PCDH7 knockdown affects autophagy and induces ferroptosis, hence strengthening colon cancer cells' sensitivity to chemotherapy by repressing the MEK1/2/ERK/c-FOS axis.

The Tubulin Code and Tubulin-Modifying Enzymes in Autophagy and Cancer

Simple Summary

Microtubules are tubulin polymers that constitute the structure of eukaryotic cells. They control different cell functions that are often deregulated in cancer, such as cell shape, cell motility and the intracellular movement of organelles. Here, we focus on the crucial role of tubulin modifications in determining different cancer characteristics, including metastatic cell migration and therapy resistance. We also discuss the influence of microtubule modifications on the autophagic process—the cellular degradation pathway that influences cancer growth. We discuss findings showing that inducing microtubule modifications can be used as a means to kill cancer cells by inhibiting autophagy.

Abstract

Microtubules are key components of the cytoskeleton of eukaryotic cells. Microtubule dynamic instability together with the “tubulin code” generated by the choice of different α- and β- tubulin isoforms and tubulin post-translational modifications have essential roles in the control of a variety of cellular processes, such as cell shape, cell motility, and intracellular trafficking, that are deregulated in cancer. In this review, we will discuss available evidence that highlights the crucial role of the tubulin code in determining different cancer phenotypes, including metastatic cell migration, drug resistance, and tumor vascularization, and the influence of modulating tubulin-modifying enzymes on cancer cell survival and aggressiveness. We will also discuss the role of post-translationally modified microtubules in autophagy—the lysosomal-mediated cellular degradation pathway—that exerts a dual role in many cancer types, either promoting or suppressing cancer growth. We will give particular emphasis to the role of tubulin post-translational modifications and their regulating enzymes in controlling the different stages of the autophagic process in cancer cells, and consider how the experimental modulation of tubulin-modifying enzymes influences the autophagic process in cancer cells and impacts on cancer cell survival and thereby represents a new and fruitful avenue in cancer therapy.