Sirtuin4 impacts mitochondrial homeostasis in pancreatic cancer cells by reducing the stability of AlkB homolog 1 via deacetylation of the HRD1-SEL1L complex

Ubiquitination regulation of mitochondrial homeostasis: a new sight for the treatment of gastrointestinal tumors

Mitochondrial homeostasis (MH) refers to the dynamic balance of mitochondrial number, function, and quality within cells. Maintaining MH is significant in the occurrence, development, and clinical treatment of Gastrointestinal (GI) tumors. Ubiquitination, as an important post-translational modification mechanism of proteins, plays a central role in the regulation of MH. Over the past decade, research on the regulation of MH by ubiquitination has focused on mitochondrial biogenesis, mitochondrial dynamics, Mitophagy, and mitochondrial metabolism during these processes. This review summarizes the mechanism and potential therapeutic targets of ubiquitin (Ub)-regulated MH intervention in GI tumors.

Role of SEL1L in the progression of solid tumors, with a special focus on its recent therapeutic potential

Since suppressor/enhancer of Lin-12-like (SEL1L) was cloned in 1997, various pieces of evidence from lower species suggest it plays a significant role in protein degradation via the ubiquitin-proteasome system. The relevance of SEL1L in many aspects of malignant transformation and tumorigenic events has been the subject of research, which has shown compelling in vitro and in vivo findings relating its altered expression to changes in tumor aggressiveness. The Endoplasmic Reticulum (ER) in tumor cells is crucial for preserving cellular proteostasis by inducing the unfolded protein response (UPR), a stress response. A crucial component of the UPR is ER-associated degradation (ERAD), which guards against ER stress-induced apoptosis and the removal of unfolded or misfolded proteins by the ubiquitin-proteasome system. As a protein stabilizer of HMG-CoA reductase degradation protein 1 (HRD1), one of the main components of ERAD, SEL1L plays an important role in ER homeostasis. Notably, the expression levels of these two proteins fluctuate independently in various cancer types, yet changes in their expression affect the levels of other associated proteins during cancer pathogenesis. Recent studies have also outlined the function of SEL1L in cancer medication resistance. This review explores the value of targeting SEL1L as a novel treatment approach for cancer, focusing on the molecular processes of SEL1L and its involvement in cancer etiology.

ALKBH1: emerging biomarker and therapeutic target for cancer treatment

As neoplastic cells proliferate, disseminate, and infiltrate, they undergo substantial alterations in their epigenetic configuration. Among the pivotal enzymes implicated in this phenomenon is the AlkB family of demethylases, notably AlkB homolog 1 (ALKBH1), which demonstrates conspicuous upregulation across various malignancies. The heightened expression of ALKBH1 renders it a compelling candidate for the development of multifaceted anticancer modalities. Despite the commendable progress achieved by investigators in elucidating the perturbations associated with ALKBH1 in malignant tissues, a comprehensive mechanism remains elusive. The present study endeavors to address this lacuna by synthesizing recent advancements pertaining to ALKBH1's involvement in oncogenesis over the preceding decade. Therefore, this research not only furnishes novel insights but also establishes a foundation for prospective initiatives aimed at cancer prophylaxis and therapeutics that exploit epigenetic regulatory mechanisms.

Sirtuins as Key Regulators in Pancreatic Cancer: Insights into Signaling Mechanisms and Therapeutic Implications

Pancreatic ductal adenocarcinoma (PDAC) stands as one of the most lethal cancers, marked by rapid progression, pronounced chemoresistance, and a complex network of genetic and epigenetic dysregulation. Within this challenging context, sirtuins, NAD+-dependent deacetylases, have emerged as pivotal modulators of key cellular processes that drive pancreatic cancer progression. Each sirtuin contributes uniquely to PDAC pathogenesis. SIRT1 influences apoptosis and chemoresistance through hypoxia, enhancing glycolytic metabolism and HIF-1α signaling, which sustain tumor survival against drugs like gemcitabine. SIRT2, conversely, disrupts cancer cell proliferation by inhibiting eIF5A, while SIRT3 exerts tumor-suppressive effects by regulating mitochondrial ROS and glycolysis. SIRT4 inhibits aerobic glycolysis, and its therapeutic upregulation has shown promise in curbing PDAC progression. Furthermore, SIRT5 modulates glutamine and glutathione metabolism, offering an avenue to disrupt PDAC's metabolic dependencies. SIRT6 and SIRT7, through their roles in angiogenesis, EMT, and metastasis, represent additional targets, with modulators of SIRT6, such as JYQ-42, showing potential to reduce tumor invasiveness. This review aims to provide a comprehensive exploration of the emerging roles of sirtuins, a family of NAD+-dependent enzymes, as critical regulators within the oncogenic landscape of pancreatic cancer. This review meticulously explores the nuanced involvement of sirtuins in pancreatic cancer, elucidating their contributions to tumorigenesis and suppression through mechanisms such as metabolic reprogramming, the maintenance of genomic integrity and epigenetic modulation. Furthermore, it emphasizes the urgent need for the development of targeted therapeutic interventions aimed at precisely modulating sirtuin activity, thereby enhancing therapeutic efficacy and optimizing patient outcomes in the context of pancreatic malignancies.

The biological function of demethylase ALKBH1 and its role in human diseases

AlkB homolog 1 (ALKBH1) is a member of the AlkB family of dioxygenases that are dependent on Fe(II) and α-ketoglutarate. Mounting evidence demonstrates that ALKBH1 exhibits enzymatic activity against various substrates, including N6-methyladenosine (m6A), N1-methyladenosine (m1A), N3-methylcytidine (m3C), 5-methylcytosine (m5C), N6-methyladenine (N6-mA, 6mA), and H2A, indicating its dual roles in different biological processes and involvement in human diseases. Up to the present, there is ongoing debate regarding ALKBH1's enzymatic activity. In this review, we present a comprehensive summary of recent research on ALKBH1, including its substrate diversity and pathological roles in a wide range of human disorders, the underlying mechanisms of its functions, and its dysregulation. We also explored the potential of ALKBH1 as a prognostic target.

Melatonin attenuates scopolamine-induced cognitive dysfunction through SIRT1/IRE1α/XBP1 pathway

BACKGROUND

The prevalence of dementia around the world is increasing, and these patients are more likely to have cognitive impairments, mood and anxiety disorders (depression, anxiety, and panic disorder), and attention deficit disorders over their lifetime. Previous studies have proven that melatonin could improve memory loss, but its specific mechanism is still confused.

METHODS

In this study, we used in vivo and in vitro models to examine the neuroprotective effect of melatonin on scopolamine (SCOP)-induced cognitive dysfunction. The behavioral tests were performed. 18F-FDG PET imaging was used to assess the metabolism of the brain. Protein expressions were determined through kit detection, Western blot, and immunofluorescence. Nissl staining was conducted to reflect neurodegeneration. MTT assay and RNAi transfection were applied to perform the in vitro experiments.

RESULTS

We found that melatonin could ameliorate SCOP-induced cognitive dysfunction and relieve anxious-like behaviors or HT22 cell damage. 18F-FDG PET-CT results showed that melatonin could improve cerebral glucose uptake in SCOP-treated mice. Melatonin restored the cholinergic function, increased the expressions of neurotrophic factors, and ameliorated oxidative stress in the brain of SCOP-treated mice. In addition, melatonin upregulated the expression of silent information regulator 1 (SIRT1), which further relieved endoplasmic reticulum (ER) stress by decreasing the expression of phosphorylate inositol-requiring enzyme (p-IRE1α) and its downstream, X-box binding protein 1 (XBP1).

CONCLUSIONS

These results indicated that melatonin could ameliorate SCOP-induced cognitive dysfunction through the SIRT1/IRE1α/XBP1 pathway. SIRT1 might be the critical target of melatonin in the treatment of dementia.

Spatial and single-cell analyses uncover links between ALKBH1 and tumor-associated macrophages in gastric cancer

BACKGROUND

AlkB homolog 1, histone H2A dioxygenase (ALKBH1), a crucial enzyme involved in RNA demethylation in humans, plays a significant role in various cellular processes. While its role in tumor progression is well-established, its specific contribution to stomach adenocarcinoma (STAD) remains elusive. This study seeks to explore the clinical and pathological relevance of ALKBH1, its impact on the tumor immune microenvironment, and its potential for precision oncology in STAD.

METHODS

We adopted a comprehensive multi-omics approach to identify ALKBH1 as an potential diagnostic biomarker for STAD, demonstrating its association with advanced clinical stages and reduced overall survival rates. Our analysis involved the utilization of publicly available datasets from GEO and TCGA. We identified differentially expressed genes in STAD and scrutinized their relationships with immune gene expression, overall survival, tumor stage, gene mutation profiles, and infiltrating immune cells. Moreover, we employed spatial transcriptomics to investigate ALKBH1 expression across distinct regions of STAD. Additionally, we conducted spatial transcriptomic and single-cell RNA-sequencing analyses to elucidate the correlation between ALKBH1 expression and immune cell populations. Our findings were validated through immunohistochemistry and bioinformatics on 60 STAD patient samples.

RESULTS

Our study unveiled crucial gene regulators in STAD linked with genetic variations, deletions, and the tumor microenvironment. Mutations in these regulators demonstrated a positive association with distinct immune cell populations across six immune datasets, exerting a substantial influence on immune cell infiltration in STAD. Furthermore, we established a connection between elevated ALKBH1 expression and macrophage infiltration in STAD. Pharmacogenomic analysis of gastric cancer cell lines further indicated that ALKBH1 inactivation correlated with heightened sensitivity to specific small-molecule drugs.

CONCLUSION

In conclusion, our study highlights the potential role of ALKBH1 alterations in the advancement of STAD, shedding light on novel diagnostic and prognostic applications of ALKBH1 in this context. We underscore the significance of ALKBH1 within the tumor immune microenvironment, suggesting its utility as a precision medicine tool and for drug screening in the management of STAD.

Regulatory factor X7 Represses Ox-LDL-Induced Proliferation and Migration of VSMCs via SIRT4-Mediated Inactivation of JAK2/STAT3 Pathway

The regulatory factor X7 (RFX7) is a vital mediator in atherosclerosis. This study aims to discuss the effect and underlying mechanism of RFX7 on the regulation of oxidized low-density lipoprotein (ox-LDL) -induced proliferation and migration of vascular smooth muscle cells (VSMCs).Ox-LDL was used to construct atherosclerosis in vitro model. The mRNA and protein levels of RFX7 and Sirtuin 4 (SIRT4) were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assays. The cellular functions were measured via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT), EdU, flow cytometry, and wound healing assay assays. The interaction between RFX7 and SIRT4 promoter was validated using chromatin immunoprecipitation and dual-luciferase reporter assays.The stimulation with ox-LDL elevated the viability of VSMCs and decreased the mRNA and protein levels of RFX7 and SIRT4 in VSMCs in a dose-dependent manner. Functionally, RFX7 overexpression restrained the VSMC viability, proliferation, and migration induced by ox-LDL, but facilitated VSMC apoptosis. RFX7 elevated SIRT4 expression via binding to its promoter. Furthermore, overexpressing either SIRT4 or RFX7 inactivated JAK2/STAT3 signaling, causing a decrease in VSMC proliferation and migration and an increase in VSMC apoptosis when exposed to ox-LDL. The impact of RFX7 overexpression on JAK2/STAT3 signaling and cellular function following ox-LDL exposure was abrogated by SIRT4 silencing.The heightened RFX7 expression restrained the proliferation and migration of ox-LDL-stimulated VSMCs via SIRT4-mediated inactivation of JAK2/STAT3 pathway.