Mitochondrial Sirtuins in Chronic Degenerative Diseases: New Metabolic Targets in Colorectal Cancer

Clinical value of serum SIRT1 combined with uterine hemodynamics in predicting disease severity and fetal growth restriction in preeclampsia

Background

To investigate the effect and correlation of serum SIRT1 combined with uterine hemodynamic parameters on disease severity and fetal uterine growth restriction in the progression of preeclampsia, and to evaluate its clinical value as potential markers.

Methods

A total of 100 patients with preeclampsia who were hospitalized in Qufu Normal University Hospital from June 2017 to June 2021 were selected as the research objects. According to the severity, they were divided into Mild group (62 cases) and Severe group (38 cases), and according to whether the fetal growth restriction was combined or not, they were divided into the Combined fetal growth restriction group (56 cases) and the Uncomplicated fetal growth restriction group (44 cases). Serum SIRT1 levels and uterine artery hemodynamic parameters were detected, and spearman analysis was used to evaluate the association of serum SIRT1 levels and uterine artery hemodynamic parameters (peak-to-trough ratio of arterial blood velocity, pulsatility index, resistance index) with disease severity (systolic blood pressure, diastolic blood pressure, and random urinary protein levels) and fetal growth restriction (femoral length, biparietal diameter, head circumference and neonatal weight); unsupervised PCA analysis, supervised PLS-DA analysis, Cluster heat map analysis, ROC curve and AUC analysis were used to evaluate the diagnostic value of serum SIRT1 levels combined with uterine artery hemodynamic parameters in the severity of disease and fetal growth restriction in patients with preeclampsia.

Results

Serum SIRT1 levels was decreased in patients with severe preeclampsia (p < 0.0001), arterial blood flow velocity peak-to-trough ratio, pulsatility index and resistance index were increased (p < 0.001; p < 0.0001), and serum SIRT1 levels and uterine artery hemodynamic parameters were closely related to disease severity (p < 0.001; p < 0.0001). In addition, the levels of serum SIRT1 in patients with preeclampsia combined with fetal growth restriction was decreased (p < 0.0001), the peak-to-trough ratio of arterial blood flow velocity, pulsatility index and resistance index were increased (p < 0.0001), and serum SIRT1 levels and uterine artery hemodynamics were closely related to fetal growth restriction (p < 0.0001). Unsupervised PCA analysis and supervised PLS-DA analysis showed that patients with different severity of disease and patients with or without fetal growth restriction were similar within groups, and there were significant differences between groups; cluster heat map analysis showed that mild and severe groups were stratified clustering, the combined fetal growth restriction group and the uncombined group were hierarchically clustered; ROC curve and AUC analysis showed that serum SIRT1 levels combined with uterine artery hemodynamic parameters had a significant effect on the severity of preeclampsia and whether combined with fetal growth restriction high diagnostic value.

Conclusions

Serum SIRT1 combined with uterine hemodynamic parameters in preeclampsia is closely related to disease severity and fetal growth restriction, and is expected to become potential biomarkers for early clinical intervention in patients.

Colorectal cancer cells with stably expressed SIRT3 demonstrate proliferating retardation by Wnt/β-catenin cascade inactivation

Colorectal cancer (CRC) is a typical and lethal digestive system malignancy. In this study, we investigated the effect of sirtuin 3 (SIRT3) expression, a fidelity mitochondrial protein, on the proliferation of CRC cells and the mechanisms involved. Using the University of Alabama at Birmingham Cancer Data Analysis Portal database and the Clinical Proteomic Tumour Analysis Consortium database, we discovered that low expression of SIRT3 in CRC was a negative factor for survival prognosis (P < .05). Meanwhile, SIRT3 expression was correlated with distant metastasis and tumour, node, metastasis stage of CRC patients (P < .05). Subsequently, we observed that CRC cells with stable SIRT3 expression exhibited a significant decrease in proliferative capacities both in vitro and in vivo, compared to their counterparts (P < .05). Further investigation using western blot, immunoprecipitation and TOPflash/FOPflash assay showed the mechanism of growth retardation of these cells was highly associated with the degradation of β-catenin in cytosol, and the localization of β-catenin/α-catenin complex in the nucleus. In conclusion, our findings suggest that the inhibition of CRC cell proliferation by SIRT3 is closely associated with the inactivation of the Wnt/β-catenin signalling pathway.

SGLT2 inhibitor promotes mitochondrial dysfunction and ER-phagy in colorectal cancer cells

BACKGROUND

Sodium-glucose transporter 2 (SGLT2) inhibitors (iSGLT2) are approved medications for type 2 diabetes. Recent studies indicate that iSGLT2 inhibit the growth of some cancer cells. However, the mechanism(s) remains to be fully elucidated.

METHODS

The SGLT2 levels were determined in normal colon CCD 841 CoN and, HCT 116, HT-29, SW480 and LoVo colorectal cancer (CRC) cell lines by quantitative real-time PCR and western blot. The effect of iSGLT2 canagliflozin on cell proliferation was examined using CCK-8, as its role on CRC cells metabolism and tumorigenesis has been evaluated by XF HS Seahorse Bioanalyzer and flow cytometric analyses. Transient gene silencing experiments and analysis of protein-protein interaction network were conducted to evaluate the SGLT2 molecular targets in CRC cells.

RESULTS

Data showed that the treatment with iSGLT2 (50 µM) for 72 h induced cell cycle arrest (p < 0.001), impaired glucose and energetic metabolism (p < 0.001), promoted apoptotic cell death and ER stress flowing into autophagy (p < 0.001) in HCT 116 and HT-29 cells. These cellular events were accompanied by sirtuin 3 (SIRT3) upregulation (p < 0.01), as also supported by SIRT3 transient silencing experiments resulting in the attenuation of the effects of iSGLT2 on the cellular metabolic/energetic alterations and the induction of programmed cell death. The identification and validation of dipeptidyl peptidase 4 (DPP4) as potential common target of SGLT2 and SIRT3 were also assessed.

CONCLUSIONS

These results deepened knowledge on the iSGLT2 contribution in limiting CRC tumorigenesis unveiling the SGLT2/SIRT3 axis in the cytotoxic mechanisms.

Mitochondrial Sirtuins in Cancer: A Revisited Review from Molecular Mechanisms to Therapeutic Strategies

The sirtuin (SIRT) family is well-known as a group of deacetylase enzymes that rely on nicotinamide adenine dinucleotide (NAD+). Among them, mitochondrial SIRTs (SIRT3, SIRT4, and SIRT5) are deacetylases located in mitochondria that regulate the acetylation levels of several key proteins to maintain mitochondrial function and redox homeostasis. Mitochondrial SIRTs are reported to have the Janus role in tumorigenesis, either tumor suppressive or oncogenic functions. Although the multi-faceted roles of mitochondrial SIRTs with tumor-type specificity in tumorigenesis, their critical functions have aroused a rising interest in discovering some small-molecule compounds, including inhibitors and activators for cancer therapy. Herein, we describe the molecular structures of mitochondrial SIRTs, focusing on elucidating their regulatory mechanisms in carcinogenesis, and further discuss the recent advances in developing their targeted small-molecule compounds for cancer therapy. Together, these findings provide a comprehensive understanding of the crucial roles of mitochondrial SIRTs in cancer and potential new therapeutic strategies.

Mitochondrial fusion-fission dynamics and its involvement in colorectal cancer

The incidence and mortality rates of colorectal cancer have elevated its status as a significant public health concern. Recent research has elucidated the crucial role of mitochondrial fusion-fission dynamics in the initiation and progression of colorectal cancer. Elevated mitochondrial fission or fusion activity can contribute to the metabolic reprogramming of tumor cells, thereby activating oncogenic pathways that drive cell proliferation, invasion, migration, and drug resistance. Nevertheless, excessive mitochondrial fission can induce apoptosis, whereas moderate mitochondrial fusion can protect cells from oxidative stress. This imbalance in mitochondrial dynamics can exert dual roles as both promoters and inhibitors of colorectal cancer progression. This review provides an in-depth analysis of the fusion-fission dynamics and the underlying pathological mechanisms in colorectal cancer cells. Additionally, it offers partial insights into the mitochondrial kinetics in colorectal cancer-associated cells, such as immune and endothelial cells. This review is aimed at identifying key molecular events involved in colorectal cancer progression and highlighting the potential of mitochondrial dynamic proteins as emerging targets for pharmacological intervention.

SIRT3 Is a Critical Regulator of Mitochondrial Function of Fibroblasts in Pulmonary Hypertension

Pulmonary hypertension (PH) is a heterogeneous and life-threatening cardiopulmonary disorder in which mitochondrial dysfunction is believed to drive pathogenesis, although the underlying mechanisms remain unclear. To determine if abnormal SIRT3 (sirtuin 3) activity is related to mitochondrial dysfunction in adventitial fibroblasts from patients with idiopathic pulmonary arterial hypertension (IPAH) and hypoxic PH calves (PH-Fibs) and whether SIRT3 could be a potential therapeutic target to improve mitochondrial function, SIRT3 concentrations in control fibroblasts, PH-Fibs, and lung tissues were determined using quantitative real-time PCR and western blot. SIRT3 deacetylase activity in cells and lung tissues was determined using western blot, immunohistochemistry staining, and immunoprecipitation. Glycolysis and mitochondrial function in fibroblasts were measured using respiratory analysis and fluorescence-lifetime imaging microscopy. The effects of restoring SIRT3 activity (by overexpression of SIRT3 with plasmid, activation SIRT3 with honokiol, and supplementation with the SIRT3 cofactor nicotinamide adenine dinucleotide [NAD+]) on mitochondrial protein acetylation, mitochondrial function, cell proliferation, and gene expression in PH-Fibs were also investigated. We found that SIRT3 concentrations were decreased in PH-Fibs and PH lung tissues, and its cofactor, NAD+, was also decreased in PH-Fibs. Increased acetylation in overall mitochondrial proteins and SIRT3-specific targets (MPC1 [mitochondrial pyruvate carrier 1] and MnSOD2 [mitochondrial superoxide dismutase]), as well as decreased MnSOD2 activity, was identified in PH-Fibs and PH lung tissues. Normalization of SIRT3 activity, by increasing its expression with plasmid or with honokiol and supplementation with its cofactor NAD+, reduced mitochondrial protein acetylation, improved mitochondrial function, inhibited proliferation, and induced apoptosis in PH-Fibs. Thus, our study demonstrated that restoration of SIRT3 activity in PH-Fibs can reduce mitochondrial protein acetylation and restore mitochondrial function and PH-Fib phenotype in PH.

Clinical Value of Serum SIRT1 Combined with Uterine Hemodynamics in Predicting Disease Severity and Fetal Growth Restriction in Preeclampsia

Objective

The sirtuin regulator 1-related enzyme (SIRT1) has been shown to play an important role in various pathophysiological processes. Our aim was to investigate the effect and correlation of serum SIRT1 combined with uterine hemodynamic parameters on disease severity and fetal uterine growth restriction in the progression of preeclampsia and to evaluate its clinical value as a potential marker.

Methods

A total of 100 patients with preeclampsia who were hospitalized in Qufu Normal University Hospital from June 2017 to June 2021 were selected as the research objects. According to the severity, they were divided into the mild (62 cases) and severe groups (38 cases), and according to whether the fetal growth restriction was combined or not, they were divided into the combined fetal growth restriction group (56 cases) and the uncomplicated fetal growth restriction group (44 cases). Serum SIRT1 expression and uterine artery hemodynamic parameters were detected, and Spearman analysis was used to evaluate the association of serum SIRT1 expression and uterine artery hemodynamic parameters (the peak-to-trough ratio of arterial blood velocity, the pulsatility index, and the resistance index) with disease severity (systolic blood pressure, diastolic blood pressure, and random urinary protein levels) and fetal growth restriction (femoral length, biparietal diameter, head circumference, and neonatal weight); unsupervised principal component analysis (PCA), supervised partial least-squares discrimination analysis (PLS-DA), cluster heat map analysis, the receiver operating characteristic (ROC) curve, and the area under curve (AUC) were used to evaluate the diagnostic value of serum SIRT1 expression combined with uterine artery hemodynamic parameters in the severity of disease and fetal growth restriction in patients with preeclampsia.

Results

Compared with patients with mild preeclampsia, serum SIRT1 expression was lower in patients with severe preeclampsia (p < 0.0001), the arterial blood flow velocity peak-to-trough ratio, pulsatility index, and resistance index were higher (p < 0.001; p < 0.0001); and serum SIRT1 expression and uterine artery hemodynamic parameters were closely related to disease severity (p < 0.001; p < 0.0001). In addition, the expression of serum SIRT1 in patients with preeclampsia combined with fetal growth restriction was lower than patients without preeclampsia (p < 0.0001); the peak-to-trough ratio of arterial blood flow velocity, the pulsatility index, and the resistance index were higher (p < 0.0001); and serum SIRT1 expression and uterine artery hemodynamics were closely related to fetal growth restriction (p < 0.0001). Unsupervised PCA analysis and supervised PLS-DA analysis showed that patients with different severity of disease and patients with or without fetal growth restriction were similar within the groups, and there were significant differences between the groups; cluster heat map analysis showed that the mild and severe groups were stratified clustering, and the combined fetal growth restriction group and the uncombined group were hierarchically clustered; ROC curve showed that the AUC of serum SIRT1 expression combined with uterine artery hemodynamic parameters was 0.776 in identifying the severity of preeclampsia and 0.956 in identifying the preeclampsia complicated by fetal growth restriction.

Conclusion

Serum SIRT1 combined with uterine hemodynamic parameters in preeclampsia is closely related to disease severity and fetal growth restriction and is expected to become a potential biomarker for early clinical intervention in patients.

SIRT3 Modulates Endothelial Mitochondrial Redox State during Insulin Resistance

Emerging evidence indicates that defects in sirtuin signaling contribute to impaired glucose and lipid metabolism, resulting in insulin resistance (IR) and endothelial dysfunction. Here, we examined the effects of palmitic acid (PA) treatment on mitochondrial sirtuins (SIRT2, SIRT3, SIRT4, and SIRT5) and oxidative homeostasis in human endothelial cells (TeloHAEC). Results showed that treatment for 48 h with PA (0.5 mM) impaired cell viability, induced loss of insulin signaling, imbalanced the oxidative status (p < 0.001), and caused negative modulation of sirtuin protein and mRNA expression, with a predominant effect on SIRT3 (p < 0.001). Restoration of SIRT3 levels by mimic transfection (SIRT3+) suppressed the PA-induced autophagy (mimic NC+PA) (p < 0.01), inflammation, and pyroptosis (p < 0.01) mediated by the NLRP3/caspase-1 axis. Moreover, the unbalanced endothelial redox state induced by PA was counteracted by the antioxidant δ-valerobetaine (δVB), which was able to upregulate protein and mRNA expression of sirtuins, reduce reactive oxygen species (ROS) accumulation, and decrease cell death. Overall, results support the central role of SIRT3 in maintaining the endothelial redox homeostasis under IR and unveil the potential of the antioxidant δVB in enhancing the defense against IR-related injuries.