SIRT7 promotes thyroid tumorigenesis through phosphorylation and activation of Akt and p70S6K1 via DBC1/SIRT1 axis

SIRT7 promotes Hippo/YAP activation and cancer cell proliferation in hepatocellular carcinoma via suppressing MST1

Abnormal activation of the oncogene YAP in the Hippo pathway is a major feature in liver cancer and inactivation of MST1/2 has been shown to be responsible for the overactivation of YAP that led to tumorigenesis. However, mechanisms underlying MST1/2 dysregulation remain poorly understood. RNA-seq analysis and genome (KEGG) pathway enrichment analysis were used to identify genes and pathways that were regulated by SIRT7. qRT-PCR, ChIP, and luciferase assay were used to investigate transcriptional regulation. Mass spectrometry, co-immunoprecipitation and immunoprecipitation were used to exam protein-protein interaction and post-transcriptional modification. A xenograft mouse model was used to confirm the effect of SIRT7 and SIRT7 inhibitors on hepatocellular carcinoma (HCC) proliferation in vivo. We found that SIRT7 suppresses MST1 by both transcriptional regulation and post-transcriptional modification, which in turn promotes YAP nuclear localization and transcriptional activation in liver cancer. Mechanistically, we revealed that SIRT7 suppresses MST1 transcription by binding to the MST1 promoter and inducing H3K18 deacetylation in its promoter region. In addition, SIRT7 directly binds to and deacetylates MST1, which primes acetylation-dependent MST1 ubiquitination and protein degradation. In clinical samples, we confirmed a negative correlation between SIRT7 and MST1 protein levels, and high SIRT7 expression correlated with elevated YAP expression and nuclear localization. In addition, SIRT7 specific inhibitor 2800Z sufficiently inhibited HCC growth by disrupting the SIRT7/MST1/YAP axis. Our data thus revealed the previously undescribed function of SIRT7 in regulating the Hippo pathway in HCC and further proved that targeting SIRT7 might provide novel therapeutic options for the treatment of liver cancer.

SIRT7: a novel molecular target for personalized cancer treatment?

The Sirtuin family of NAD+-dependent enzymes assumes a pivotal role in orchestrating adaptive responses to environmental fluctuations and stress stimuli, operating at both genomic and metabolic levels. Within this family, SIRT7 emerges as a versatile player in tumorigenesis, displaying both pro-tumorigenic and tumor-suppressive functions in a context-dependent manner. While other sirtuins, such as SIRT1 and SIRT6, exhibit a similar dual role in cancer, SIRT7 stands out due to distinctive attributes that sharply distinguish it from other family members. Among these are a unique key role in regulation of nucleolar functions, a close functional relationship with RNA metabolism and processing -exceptional among sirtuins- and a complex multienzymatic nature, which provides a diverse range of molecular targets. This review offers a comprehensive overview of the current understanding of the role of SIRT7 in various malignancies, placing particular emphasis on the intricate molecular mechanisms employed by SIRT7 to either stimulate or counteract tumorigenesis. Additionally, it delves into the unique features of SIRT7, discussing their potential and specific implications in tumor initiation and progression, underscoring the promising avenue of targeting SIRT7 for the development of innovative anti-cancer therapies.

Inhibition of SIRT7 promotes STAT1 activation and STAT1-dependent signaling in hepatocellular carcinoma

The signal transducer and activator of transcription 1 (STAT1) plays a crucial role in regulating tumor progression. However, the mechanisms governing its phosphorylation and biological functions remain incompletely understood. Here, we present compelling evidence indicating that knockdown of SIRT7 inhibits Smurf1-induced ubiquitination of STAT1, consequently impeding the proteasome pathway degradation of STAT1. This inhibition leads to increased stability of STAT1 and enhanced binding to JAK1. Importantly, SIRT7 exerts a negative regulatory effect on STAT1 activation and IFN-γ/STAT1 signaling in hepatocellular carcinoma (HCC). Etoposide treatment not only facilitates STAT1 activation but also downregulates SIRT7 expression. Notably, knockdown of STAT1 in SIRT7-deficient cells attenuates the increase in cell apoptosis induced by Etoposide treatment. In conclusion, our data shed light on the intricate interplay between ubiquitination, STAT1, SIRT7, and Smurf1, elucidating their impact on STAT1-related signaling. These insights contribute to a more comprehensive understanding of the molecular mechanisms involved in STAT1 regulation and suggest potential avenues for the development of targeted therapies against cancer.

A tumor-suppressing role of TSPYL2 in thyroid cancer: Through interacting with SIRT1 and repressing SIRT1/AKT pathway

Thyroid cancer is one of the most common endocrine cancers. Testis-specific protein, Y-encoded-like 2 (TSPYL2) belongs to the TSPY family. Studies show that TSPYL2 plays as a cancer suppressor in several cancers. However, the role of TSPYL2 in thyroid cancer remains elusive. In the present study, the expression of TSPYL2 in human central papillary thyroid cancer (PTC) tissues and corresponding para-cancer tissues was detected by qPCR and Western blot. The gain- and loss-of-function studies for TSPYL2 were performed in TPC-1 cells and IHH-4 cells. The results showed that TSPYL2 expression was decreased in PTC tissues, and the low TSPYL2 expression was associated with more lymph node metastasis. Moreover, the results showed that knockdown of TSPYL2 promoted proliferation and enhanced the ability of migration and invasion of TPC-1 cells and IHH-4 cells, while TSPYL2 overexpression reversed it. TSPYL2 overexpression arrested cell cycle. We found that TSPYL2 silencing suppressed cell apoptosis, while overexpression of TSPYL2 reversed it. Co-IP results illustrated that TSPYL2 interacted with SIRT1. Knockdown of TSPYL2 increased the association between SIRT1 and AKT. Moreover, TSPYL2 expression inhibited AKT activation by upregulating the AKT acetylation level. In vivo, tumor xenograft experiments indicated that TSPYL2 suppressed the tumorigenic ability of thyroid cancer cells. Western blot results suggested that knockdown of TSPYL2 enhanced the phosphorylation level of AKT, while TSPYL2 overexpression reversed it. Taken together, our study suggested TSPYL2 could be a tumor suppressor in thyroid cancer by regulating SIRT1/AKT pathway.

SLC39A10 promotes malignant phenotypes of gastric cancer cells by activating the CK2-mediated MAPK/ERK and PI3K/AKT pathways

Solute carrier family 39 member 10 (SLC39A10) belongs to a subfamily of zinc transporters and plays a key role in B-cell development. Previous studies have reported that its upregulation promotes breast cancer metastasis by enhancing the influx of zinc ions (Zn2+); however, its role in gastric cancer remains totally unclear. Here, we found that SLC39A10 expression was frequently increased in gastric adenocarcinomas and that SLC39A10 upregulation was strongly associated with poor patient outcomes; in addition, we identified SLC39A10 as a direct target of c-Myc. Functional studies showed that ectopic expression of SLC39A10 in gastric cancer cells dramatically enhanced the proliferation, colony formation, invasiveness abilities of these gastric cancer cells and tumorigenic potential in nude mice. Conversely, SLC39A10 knockdown inhibited gastric cancer cell proliferation and colony formation. Mechanistically, SLC39A10 exerted its carcinogenic effects by increasing Zn2+ availability and subsequently enhancing the enzyme activity of CK2 (casein kinase 2). As a result, the MAPK/ERK and PI3K/AKT pathways, two major downstream effectors of CK2, were activated, while c-Myc, a downstream target of these two pathways, formed a vicious feedback loop with SLC39A10 to drive the malignant progression of gastric cancer. Taken together, our data demonstrate that SLC39A10 is a functional oncogene in gastric cancer and suggest that targeting CK2 is an alternative therapeutic strategy for gastric cancer patients with high SLC39A10 expression.

SIRT7 orchestrates melanoma progression by simultaneously promoting cell survival and immune evasion via UPR activation

Melanoma is the most lethal type of skin cancer, originating from the malignant transformation of melanocyte. While the development of targeted therapy and immunotherapy has gained revolutionary advances in potentiating the therapeutic effect, the prognosis of patients with melanoma is still suboptimal. During tumor progression, melanoma frequently encounters stress from both endogenous and exogenous sources in tumor microenvironment. SIRT7 is a nuclear-localized deacetylase of which the activity is highly dependent on intracellular nicotinamide adenine dinucleotide (NAD⁺), with versatile biological functions in maintaining cell homeostasis. Nevertheless, whether SIRT7 regulates tumor cell biology and tumor immunology in melanoma under stressful tumor microenvironment remains elusive. Herein, we reported that SIRT7 orchestrates melanoma progression by simultaneously promoting tumor cell survival and immune evasion via the activation of unfolded protein response. We first identified that SIRT7 expression was the most significantly increased one in sirtuins family upon stress. Then, we proved that the deficiency of SIRT7 potentiated tumor cell death under stress in vitro and suppressed melanoma growth in vivo. Mechanistically, SIRT7 selectively activated the IRE1α-XBP1 axis to potentiate the pro-survival ERK signal pathway and the secretion of tumor-promoting cytokines. SIRT7 directly de-acetylated SMAD4 to antagonize the TGF-β-SMAD4 signal, which relieved the transcriptional repression on IRE1α and induced the activation of the IRE1α-XBP1 axis. Moreover, SIRT7 up-regulation eradicated anti-tumor immunity by promoting PD-L1 expression via the IRE1α-XBP1 axis. Additionally, the synergized therapeutic effect of SIRT7 suppression and anti-PD-1 immune checkpoint blockade was also investigated. Taken together, SIRT7 can be employed as a promising target to restrain tumor growth and increase the effect of melanoma immunotherapy.

Sorafenib/2800Z Co-Loaded into Cholesterol and PEG Grafted Polylysine NPs for Liver Cancer Treatment

The treatment of liver cancer remains challenging due to the low responsiveness of advanced cancer to therapeutic options. Sorafenib is the first line chemotherapeutic drug for advanced liver cancer but is frequently associated with severe side effects lead to discontinuation of chemotherapy. We previously developed a specific SIRT7 inhibitor 2800Z, which suppressed tumor growth and enhanced the chemosensitivity of sorafenib. In this study, we constructed polylysine polymer nanoparticles modified with cholesterol and GSH-sensitive PEG (mPssPC) to load sorafenib (SOR) and the SIRT7 inhibitor 2800Z to form dual-loaded NPs (S2@PsPCs) to reduce the toxicity and increase efficacy of sorafenib in liver cancer. The average size of S2@PsPC NPs was approximately 370 nm and the zeta potential was approximately 50-53 mV. We found that the release of the drugs exhibited pH sensitivity and was significantly accelerated in an acid release medium simulating the tumor environment. In addition, S2@PsPC NPs inhibited the proliferation and induced apoptosis of liver cancer cells in vitro. An in vivo study further revealed that S2@PsPCs showed high specificity to the liver cancer but low affinity and toxicity to the main organs including the heart, kidneys, lungs, and liver. Our data thus further approved the combination of a SIRT7 inhibitor and sorafenib for the treatment of liver cancer and provided new drug delivery system for targeted therapy.

MiR-342-5p protects neurons from cerebral ischemia induced-apoptosis through regulation of Akt/NF-κB pathways by targeting CCAR2

OBJECTIVES

Ischemic stroke causes high morbidity, mortality and health burden in the world. MiR-342-5p was associated with Alzheimer's disease and cardio-protection. Herein, we aimed to reveal effects of miR-342-5p on cerebral ischemia injury as well as novel targets for stroke.

MATERIALS AND METHODS

AgomiR-342-5p was intracerebroventricularly injected into the middle cerebral artery occlusion (MCAO) mouse models to evaluate functions of miR-342-5p on cerebral ischemia. RT-qPCR and western blot assays were used to evaluate genes expression. Oxygen-glucose deprivation (OGD) was used as an in vitro model for ischemia. Viability and apoptosis ratio of neurons was evaluated by CCK-8, LDH release detection, and flow cytometry. The potential targets of miR-342-5p were predicted by Targetscan, and their interaction was confirmed by luciferase assay.

RESULTS

The intervention of miR-342-5p effectively attenuated ischemic injury in MCAO mice. MiR-342-5p overexpression could protect neurons against OGD-induced injury, as revealed by increased cell viability and BCL2 expression, and decreased LDH release, apoptosis ratio, and BAX expression in OGD-induced neurons. Mechanically, miR-342-5p could directly bound with CCAR2 to inhibit its expression. Overexpressing CARR2 aggravated the OGD-induced injury of neurons, which was partly restrained by overexpressing miR-342-5p reversed. Furthermore, miR-342-5p/CARR2 axis regulates Akt/NF-κB signaling pathway in vitro as well as in vivo cerebral ischemia models.

CONCLUSIONS

MiR-342-5p inhibited neuron apoptosis by regulating Akt/NF-kB signaling pathway via CCAR2 suppression. Our findings revealed the neuroprotection of miR-342-5p in cerebral ischemia.

CYP2E1-dependent upregulation of SIRT7 is response to alcohol mediated metastasis in hepatocellular carcinoma

Long-term alcohol use is a confirmed risk factor of liver cancer tumorigenesis and metastasis. Multiple mechanisms responsible for alcohol related tumorigenesis have been proposed, including toxic reactive metabolite production, oxidative stress and fat accumulation. However, mechanisms underlying alcohol-mediated liver cancer metastasis remain largely unknown. We have previously demonstrated that SIRT7 regulates chemosensitivity by altering a p53-dependent pathway in human HCC. In the current study, we further revealed that SIRT7 is a critical factor in promoting liver cancer metastasis. SIRT7 expression is associated with disease stage and high SIRT7 predicts worse overall and disease-free survival. Overexpression of SIRT7 promotes HCC cell migration and EMT while knockdown of SIRT7 showed opposite effects. Mechanistically, we found that SIRT7 suppresses E-Cadherin expression through FOXO3-dependent promoter binding and H3K18 deacetylation. Knockdown of FOXO3 abolished the suppressive effect of SIRT7 on E-cadherin transcription. More importantly, we identified that alcohol treatment upregulates SIRT7 and suppresses E-cadherin expression via a CYP2E/ROS axis in hepatocytes both in vitro and in vivo. Antioxidant treatment in primary hepatocyte or CYP2E1-/- mice fed with alcohol impaired those effects. Reducing SIRT7 activity completely abolished alcohol-mediated promotion of liver cancer metastasis in vivo. Taken together, our data reveal that SIRT7 is a pivotal regulator of alcohol-mediated HCC metastasis.

Histone acetylation modifications: A potential targets for the diagnosis and treatment of papillary thyroid cancer

Thyroid cancer is a common malignancy of the endocrine system, with papillary thyroid cancer (PTC) being the most common type of pathology. The incidence of PTC is increasing every year. Histone acetylation modification is an important part of epigenetics, regulating histone acetylation levels through histone acetylases and histone deacetylases, which alters the proliferation and differentiation of PTC cells and affects the treatment and prognosis of PTC patients. Histone deacetylase inhibitors induce histone acetylation, resulting in the relaxation of chromatin structure and activation of gene transcription, thereby promoting differentiation, apoptosis, and growth arrest of PTC cells.

Potential of histone deacetylase inhibitors in the control and regulation of prostate, breast and ovarian cancer

Histone deacetylases (HDACs) are enzymes that play a role in chromatin remodeling and epigenetics. They belong to a specific category of enzymes that eliminate the acetyl part of the histones’ -N-acetyl lysine, causing the histones to be wrapped compactly around DNA. Numerous biological processes rely on HDACs, including cell proliferation and differentiation, angiogenesis, metastasis, gene regulation, and transcription. Epigenetic changes, specifically increased expression and activity of HDACs, are commonly detected in cancer. As a result, HDACi could be used to develop anticancer drugs. Although preclinical outcomes with HDACs as monotherapy have been promising clinical trials have had mixed results and limited success. In both preclinical and clinical trials, however, combination therapy with different anticancer medicines has proved to have synergistic effects. Furthermore, these combinations improved efficacy, decreased tumor resistance to therapy, and decreased toxicity. In the present review, the detailed modes of action, classification of HDACs, and their correlation with different cancers like prostate, breast, and ovarian cancer were discussed. Further, the different cell signaling pathways and the structure-activity relationship and pharmaco-toxicological properties of the HDACi, and their synergistic effects with other anticancer drugs observed in recent preclinical and clinical studies used in combination therapy were discussed for prostate, breast, and ovarian cancer treatment.

Hypoxia-induced proteasomal degradation of DBC1 by SIAH2 in breast cancer progression

DBC1 has been characterized as a key regulator of physiological and pathophysiological activities, such as DNA damage, senescence, and tumorigenesis. However, the mechanism by which the functional stability of DBC1 is regulated has yet to be elucidated. Here, we report that the ubiquitination-mediated degradation of DBC1 is regulated by the E3 ubiquitin ligase SIAH2 and deubiquitinase OTUD5 under hypoxic stress. Mechanistically, hypoxia promoted DBC1 to interact with SIAH2 but not OTUD5, resulting in the ubiquitination and subsequent degradation of DBC1 through the ubiquitin–proteasome pathway. SIAH2 knockout inhibited tumor cell proliferation and migration, which could be rescued by double knockout of SIAH2/CCAR2. Human tissue microarray analysis further revealed that the SIAH2/DBC1 axis was responsible for tumor progression under hypoxic stress. These findings define a key role of the hypoxia-mediated SIAH2-DBC1 pathway in the progression of human breast cancer and provide novel insights into the metastatic mechanism of breast cancer.

Akt-Dependent Glycolysis-Driven Lipogenesis Supports Proliferation and Survival of Human Pulmonary Arterial Smooth Muscle Cells in Pulmonary Hypertension

Hyper-proliferation of pulmonary arterial vascular smooth muscle cells (PAVSMC) is an important pathological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). Lipogenesis is linked to numerous proliferative diseases, but its role in PAVSMC proliferation in PAH remains to be elucidated. We found that early-passage human PAH PAVSMC had significant up-regulation of key fatty acids synthesis enzymes ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FASN), and increased unstimulated proliferation compared to control human PAVSMC. Treatment with an allosteric ACC inhibitor 5-tetradecyloxy-2-furoic acid (TOFA) significantly decreased proliferation and induced apoptosis of human PAH PAVSMC. Intracellular lipid content and proliferation of PAH PAVSMC were not reduced by incubation in lipid-depleted media but suppressed by a non-metabolizable analog of glucose 2-Deoxy-D-glucose (2-DG) and partially restored by addition of pyruvate. Protein kinase Akt was upregulated in human PAH PAVSMC in a sirtuin 7 (SIRT7)- and c-Jun N-terminal kinase (JNK)-dependent manner. Pharmacological inhibition of Akt down-regulated ACLY and ACC, significantly reduced intracellular lipid content, inhibited proliferation and induced apoptosis of human PAH PAVSMC. Taken together, these data demonstrate that human PAH PAVSMC have up-regulated lipogenesis, which is supported in an Akt- and glycolysis-dependent manner and is required for increased proliferation and survival. Our data suggest that there is a mechanistic link between glycolysis, lipogenesis, and the proliferation of human PAH PAVSMC and call for further studies to determine the potential attractiveness of a SIRT7/JNK-Akt-lipogenesis axis as a target pathway to inhibit PAVSMC hyper-proliferation in PAH.

Posttranslational Modifications in Thyroid Cancer: Implications for Pathogenesis, Diagnosis, Classification, and Treatment

There is evidence that posttranslational modifications, including phosphorylation, acetylation, methylation, ubiquitination, sumoylation, glycosylation, and succinylation, may be involved in thyroid cancer. We review recent reports supporting a role of posttranslational modifications in the tumorigenesis of thyroid cancer, sensitivity to radioiodine and other types of treatment, the identification of molecular treatment targets, and the development of molecular markers that may become useful as diagnostic tools. An increased understanding of posttranslational modifications may be an important supplement to the determination of alterations in gene expression that has gained increasing prominence in recent years.

Targeting autophagy in prostate cancer: preclinical and clinical evidence for therapeutic response

Prostate cancer is a leading cause of death worldwide and new estimates revealed prostate cancer as the leading cause of death in men in 2021. Therefore, new strategies are pertinent in the treatment of this malignant disease. Macroautophagy/autophagy is a “self-degradation” mechanism capable of facilitating the turnover of long-lived and toxic macromolecules and organelles. Recently, attention has been drawn towards the role of autophagy in cancer and how its modulation provides effective cancer therapy. In the present review, we provide a mechanistic discussion of autophagy in prostate cancer. Autophagy can promote/inhibit proliferation and survival of prostate cancer cells. Besides, metastasis of prostate cancer cells is affected (via induction and inhibition) by autophagy. Autophagy can affect the response of prostate cancer cells to therapy such as chemotherapy and radiotherapy, given the close association between autophagy and apoptosis. Increasing evidence has demonstrated that upstream mediators such as AMPK, non-coding RNAs, KLF5, MTOR and others regulate autophagy in prostate cancer. Anti-tumor compounds, for instance phytochemicals, dually inhibit or induce autophagy in prostate cancer therapy. For improving prostate cancer therapy, nanotherapeutics such as chitosan nanoparticles have been developed. With respect to the context-dependent role of autophagy in prostate cancer, genetic tools such as siRNA and CRISPR-Cas9 can be utilized for targeting autophagic genes. Finally, these findings can be translated into preclinical and clinical studies to improve survival and prognosis of prostate cancer patients.

• Prostate cancer is among the leading causes of death in men where targeting autophagy is of importance in treatment;

• Autophagy governs proliferation and metastasis capacity of prostate cancer cells;

• Autophagy modulation is of interest in improving the therapeutic response of prostate cancer cells;

• Molecular pathways, especially involving non-coding RNAs, regulate autophagy in prostate cancer;

• Autophagy possesses both diagnostic and prognostic roles in prostate cancer, with promises for clinical application.

SIRT7 is a Prognostic Biomarker in Kidney Renal Clear Cell Carcinoma That is Correlated with Immune Cell Infiltration

Background

SIRT7 has been shown to be expressed in many cancer types, including clear cell renal cell carcinoma (KIRC), but its functional role in this oncogenic context remains to be firmly defined. This study was designed to explore correlations between SIRT7 and KIRC characteristics using the TCGA database.

Methods

Relationships between SIRT7 expression and KIRC patient clinicopathological characteristics were assessed through Kruskal–Wallis tests, Wilcoxon signed-rank tests, and logistic regression analyses. Area under the ROC curve (AUC) values were used to assess the prognostic value of SIRT7 as a means of classifying clear cell renal cell carcinoma patients. The functional role of SIRT7 in this cancer type was assessed through GO/KEGG enrichment analyses and immune cell infiltration analyses.

Results

In KIRC patients, higher levels of SIRT7 expression were associated with Race, M stage, T stage (all P < 0.05). SIRT7 offered significant diagnostic value in ROC curve analyses (AUC = 0.912), and elevated SIRT7 levels were linked to worse patient overall survival (OS; P < 0.001). The expression of SIRT7 was independently related with KIRC patient OS (HR: 1.827; 95% CI: 1.346–2.481; P<0.001). In GO/KEGG analyses, SIRT7 was found to be associated with ubiquitin-mediated proteolysis and nucleotide excision repair. Higher SIRT7 expression was related to the enhanced infiltration of certain immune cells.

Conclusion

Increased SIRT7 expression was associated with a worse KIRC patient prognosis, and immune infiltrates, suggesting it may offer value as a prognostic biomarker for this cancer type.

Discovery of SIRT7 Inhibitor as New Therapeutic Options Against Liver Cancer

Optimal therapeutic strategies for liver cancer patients remain challenging due to the high recurrence rate after surgical resection and chemotherapy resistance. Emerging evidence has shown that epigenetic factor SIRT7 is involved in various aspects of cancer biology, while inactive SIRT7 reverses human cancer phenotype and suppresses tumor growth. In the present study, we predicted the SIRT7 structure by using the fold recognition (or threading) method and performed structure-based virtual screening to develop specific SIRT7 inhibitor by docking 939319 structurally diverse compounds with SIRT proteins. Compounds with high affinities to SIRT7 but low affinities to other SIRT proteins were chosen as candidates of specific SIRT7 inhibitor. Our leading compounds 2800Z and 40569Z showed strong interaction with SIRT7 protein, and specifically inhibited SIRT7 deacetylation activity in vitro. Our docking results also revealed that ARG-120, TRP-126, and HIS-187 were critical sites responsible for interaction of SIRT7 with small molecules. Mutations in the aforementioned sites significantly abolished interaction and inhibitory effects of compounds to SIRT7. In addition, in vivo data indicated that compounds 2800Z and 40569Z were able to induce apoptosis and increase chemosensitivity to sorafenib in human liver cancer. Our findings demonstrated targeting SIRT7 may offer novel therapeutic options for cancer management, and the value of compounds 2800Z and 40569Z as chemical probes for the study of SIRT7 biological functions as well as starting leads for the development of new therapeutic options against liver cancer.

Bioinformatic Analysis of the Effect of the Sirtuin Family on Differentiated Thyroid Carcinoma

A growing body of experimental evidence suggests that sirtuins (SIRTs) are associated with tumorigenesis in differentiated thyroid cancer (DTC). Nevertheless, the involvement of SIRTs in the pathogenesis of DTC and their clinical value remain ill-defined and should be thoroughly examined. We explored the transcription of SIRTs and survival data of patients with DTC by the systematic utilization of bioinformatics to analyze data of publicly accessible databases including Oncomine, cBioPortal, Kaplan-Meier Plotter, Gene Expression Profiling Interactive Analysis (GEPIA), Protein Atlas, LinkedOmics, and GSCALite. The examination of gene expression profiles showed that SIRT2, SIRT3, SIRT4, SIRT5, and SIRT6 were downregulated in DTC tissues compared with the normal thyroid tissues. The decreased expression levels of SIRT2, SIRT4, and SIRT5 were correlated with advanced tumor stages. The survival results showed that the increased SIRT4 mRNA expression level was associated with improved overall survival (OS) in the DTC patients. In addition, patients with DTC with high SIRT2, SIRT3, SIRT4, and SIRT5 mRNA levels had higher disease-free survival (DFS). These results showed that SIRT2, SIRT3, SIRT4, SIRT5, and SIRT6 are potential targets for precise treatment of DTC patients and that SIRT2, SIRT3, SIRT4, and SIRT5 are novel potential biomarkers for the prognosis of DTC.

Potential Novel Modules and Hub Genes as Prognostic Candidates of Thyroid Cancer by Weighted Gene Co-Expression Network Analysis

Background

Although thyroid cancer (THCA) is one of the most common type of endocrine malignancy, its highly complex molecular mechanisms of carcinogenesis are not completely known.

Materials and Methods

In this study, weighted gene co-expression network analysis (WGCNA) was utilized to construct gene co-expression networks and evaluate the relations between modules and clinical traits to identify potential prognostic biomarkers for THCA patients. RNA-seq data and clinical data were downloaded from The Cancer Genome Atlas (TCGA). Other independent datasets from the Gene Expression Omnibus (GEO) database and the Human Protein Atlas database were performed to validate findings.

Results

Finally, 11 co-expression modules were constructed and four hub genes, CCDC146, SLC4A4, TDRD9 and MUM1L1, were identified and validated statistically, which were considerably interrelated to worse survival of THCA patients.

Conclusion

This research study revealed four hub genes may be considered candidate prognostic biomarkers and potential therapeutic targets for THCA patients in the future.

Norcantharidin combined with paclitaxel induces endoplasmic reticulum stress mediated apoptotic effect in prostate cancer cells by targeting SIRT7 expression

Prostate cancer (PCa), an extremely common malignancy in males, is the most prevalent disease in several countries. Norcantharidin (NCTD) has antiproliferation, antimetastasis, apoptosis, and autophagy effects in various tumor cells. Nevertheless, the antitumor effect of NCTD combined with paclitaxel (PTX), a chemotherapeutic drug, in PCa remains unknown. The cell growth, proliferative rate, cell cycle distribution, and cell death were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, colony formation assay, PI staining, and Annexin V/PI staining by flow cytomertry, whereas the mitochondrial membrane potential (MMP) and endoplasmic reticulum (ER) stress was evaluated using the MitoPotential assay and ER-ID red assay. We also evaluated the protein and mRNA expression of SIRTs by Western blotting and qRTPCR assay. Overexpression effectivity was measured by DNA transfection assay. Our study showed that cell viability and proliferative PC3 and DU145 rates were effectively inhibited after NCTD-PTX combination. We also found that NCTD-PTX combination treatment significantly enhance G2/M phase arrest, induction of cell death and ER stress, loss of MMP, and ER- or apoptotic-related protein expression. Furthermore, NCTD-PTX combination treatment was significantly decreasing the protein and mRNA expression of SIRT7 in PCa cells. Combination therapy effectively reduced cell viability, ER stress-mediated apoptosis and p-eIF2α/ATF4/CHOP/cleaved-PARP expression inhibition in SIRT7 overexpression of PCa cells. These results indicate that NCTD combined with PTX induces ER stress-mediated apoptosis of PCa cells by regulating the SIRT7 expression axis. Moreover, combination therapy may become a potential therapeutic strategy against human PCa.

The noncoding RNAs SNORD50A and SNORD50B-mediated TRIM21-GMPS interaction promotes the growth of p53 wild-type breast cancers by degrading p53

Small nucleolar RNA SNORD50A and SNORD50B (SNORD50A/B) has been reported to be recurrently deleted and function as a putative tumor suppressor in different types of cancer by binding to and suppressing the activity of the KRAS oncoproteins. Its deletion correlates with poorer patient survival. However, in this study, we surprisingly found that SNORD50A/B loss predicted a better survival in breast cancer patients carrying wild-type p53. Functional studies showed that SNORD50A/B deletion strongly inhibited the proliferation, migration, invasion and tumorigenic potential, and induced cell cycle arrest and apoptosis in p53 wild-type breast cancer cells, while exerted the opposite effects in p53 mutated breast cancer cells. This was also supported by ectopically expressing SNORD50A/B in both p53 wild-type and mutated breast cancer cells. Mechanistically, SNORD50A/B clearly enhances the interaction between E3 ubiquitin ligase TRIM21 and its substrate GMPS by forming a complex among them, thereby promoting GMPS ubiquitination and its subsequent cytoplasmic sequestration. SNORD50A/B deletion in p53 wild-type breast cancer cells will release GMPS and induce the translocation of GMPS into the nucleus, where GMPS can recruit USP7 and form a complex with p53, thereby decreasing p53 ubiquitination, stabilizing p53 proteins, and inhibiting malignant phenotypes of cancer cells. Altogether, the present study first reports that SNORD50A/B plays an oncogenic role in p53 wild-type breast cancers by mediating TRIM21-GMPS interaction.

Sirtuins as Important Factors in Pathological States and the Role of Their Molecular Activity Modulators

Sirtuins (SIRTs), enzymes from the family of NAD⁺-dependent histone deacetylases, play an important role in the functioning of the body at the cellular level and participate in many biochemical processes. The multi-directionality of SIRTs encourages scientists to undertake research aimed at understanding the mechanisms of their action and the influence that SIRTs have on the organism. At the same time, new substances are constantly being sought that can modulate the action of SIRTs. Extensive research on the expression of SIRTs in various pathological conditions suggests that regulation of their activity may have positive results in supporting the treatment of certain metabolic, neurodegenerative or cancer diseases or this connected with oxidative stress. Due to such a wide spectrum of activity, SIRTs may also be a prognostic markers of selected pathological conditions and prove helpful in assessing their progression, especially by modulating their activity. The article presents and discusses the activating or inhibiting impact of individual SIRTs modulators. The review also gathered selected currently available information on the expression of SIRTs in individual disease cases as well as the biological role that SIRTs play in the human organism, also in connection with oxidative stress condition, taking into account the progress of knowledge about SIRTs over the years, with particular reference to the latest research results.

Participation of MicroRNAs in the Treatment of Cancer with Phytochemicals

Cancer is a global health concern and one of the main causes of disease-related death. Even with considerable progress in investigations on cancer therapy, effective anti-cancer agents and regimens have thus far been insufficient. There has been compelling evidence that natural phytochemicals and their derivatives have potent anti-cancer activities. Plant-based anti-cancer agents, such as etoposide, irinotecan, paclitaxel, and vincristine, are currently being applied in medical treatments for patients with cancer. Further, the efficacy of plenty of phytochemicals has been evaluated to discover a promising candidate for cancer therapy. For developing more effective cancer therapy, it is required to apprehend the molecular mechanism deployed by natural compounds. MicroRNAs (miRNAs) have been realized to play a pivotal role in regulating cellular signaling pathways, affecting the efficacy of therapeutic agents in cancer. This review presents a feature of phytochemicals with anti-cancer activity, focusing mainly on the relationship between phytochemicals and miRNAs, with insights into the role of miRNAs as the mediators and the regulators of anti-cancer effects of phytochemicals.

Implications of NAD+ boosters in translational medicine

Nicotinamide adenine dinucleotide (NAD⁺ ) is an essential metabolite in energy metabolism as well as a co-substrate in biochemical reactions such as protein deacylation, protein ADP-ribosylation and cyclic ADP-ribose synthesis mediated by sirtuins, poly (ADP-ribose) polymerases (PARPs) and CD38. In eukaryotic cells, NAD⁺ is synthesized through three distinct pathways, which offer different strategies to modulate the bioavailability of NAD⁺ . The therapeutic potential of dietarily available NAD⁺ boosters preserving the NAD⁺ pool has been attracting attention after the discovery of declining NAD⁺ levels in ageing model organisms as well as in several age-related diseases, including cardiometabolic and neurodegenerative diseases. Here, we review the recent advances in the biology of NAD⁺ , including the salubrious effects of NAD⁺ boosters and discuss their future translational strategies.

The Roles of Histone Deacetylases and Their Inhibitors in Cancer Therapy

Genetic mutations and abnormal gene regulation are key mechanisms underlying tumorigenesis. Nucleosomes, which consist of DNA wrapped around histone cores, represent the basic units of chromatin. The fifth amino group (Nε) of histone lysine residues is a common site for post-translational modifications (PTMs), and of these, acetylation is the second most common. Histone acetylation is modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), and is involved in the regulation of gene expression. Over the past two decades, numerous studies characterizing HDACs and HDAC inhibitors (HDACi) have provided novel and exciting insights concerning their underlying biological mechanisms and potential anti-cancer treatments. In this review, we detail the diverse structures of HDACs and their underlying biological functions, including transcriptional regulation, metabolism, angiogenesis, DNA damage response, cell cycle, apoptosis, protein degradation, immunity and other several physiological processes. We also highlight potential avenues to use HDACi as novel, precision cancer treatments.

CYP2S1 is a synthetic lethal target in BRAFV600E-driven thyroid cancers

BRAF^V600E is the most common genetic alteration and has become a major therapeutic target in thyroid cancers; however, intrinsic feedback mechanism limited clinical use of BRAF^V600E specific inhibitors. Synthetic lethal is a kind of interaction between two genes, where only simultaneously perturbing both of the genes can lead to lethality. Here, we identified CYP2S1 as a synthetic lethal partner of BRAF^V600E in thyroid cancers. First, we found that CYP2S1 was highly expressed in papillary thyroid cancers (PTCs) compared to normal thyroid tissues, particularly in conventional PTCs (CPTCs) and tall-cell PTCs (TCPTCs), and its expression was positively associated with BRAF^V600E mutation. CYP2S1 knockdown selectively inhibited cell proliferation, migration, invasion and tumorigenic potential in nude mice, and promoted cell apoptosis in BRAF^V600E mutated thyroid cancer cells, but not in BRAF wild-type ones. Mechanistically, BRAF^V600E-mediated MAPK/ERK cascade upregulated CYP2S1 expression by an AHR-dependent pathway, while CYP2S1 in turn enhanced transcriptional activity of AHR through its metabolites. This AHR/CYP2S1 feedback loop strongly amplified oncogenic role of BRAF^V600E in thyroid cancer cells, thereby causing synthetic lethal interaction between CYP2S1 and BRAF^V600E. Finally, we demonstrated CYP2S1 as a potential therapeutic target in both BRAF^V600E-drived xenograft and transgenic mouse models by targetedly delivering CYP2S1-specific siRNA. Altogether, our data demonstrate CYP2S1 as a synthetic lethal partner of BRAF^V600E in thyroid cancers, and indicate that targeting CYP2S1 will provide a new therapeutic strategy for BRAF^V600E mutated thyroid cancers.

An NAD+-Dependent Deacetylase SIRT7 Promotes HCC Development Through Deacetylation of USP39

Ubiquitin specific protease 39 (USP39), an ortholog of Sad1p in yeast, is essential for spliceosome assembly during pre-mRNA splicing in human. Although it is known that USP39 is upregulated and plays an oncogenic role in hepatocellular carcinoma (HCC), the underlying mechanism remains unknown. The results of this study demonstrated that USP39 can be acetylated by the histone acetyltransferase MYST1, which is required for its proteasome-mediated degradation by Von Hippel-Lindau protein. In HCC cells, USP39 interacts with and is deacetylated by the lysine deacetylase sirtuin 7 (SIRT7). Notably, the deacetylation of USP39 by SIRT7 promotes its stability and thereby accelerates HCC cell proliferation and tumorigenesis in vitro and in vivo. Our data demonstrated a novel mechanism by which SIRT7 modulates the deacetylation of USP39 to promote HCC development, thus providing an effective anti-tumor therapeutic strategy for HCC.

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SIRT7 modulates the deacetylation of USP39

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MYST1 promotes the acetyl binding of USP39

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USP39 acetylation induces its instability

Sirtuin 7 promotes non‑small cell lung cancer progression by facilitating G1/S phase and epithelial‑mesenchymal transition and activating AKT and ERK1/2 signaling

Increasing evidence has indicated the roles of sirtuin 7 (SIRT7) in numerous human cancers. However, the effects and the clinical significance of SIRT7 in human lung cancer is largely unknown. The present research demonstrated that SIRT7 was increased in human lung cancer tumor tissues. SIRT7 upregulation was associated with clinicopathological characteristics of lung cancer malignancy including positive lymph node metastasis, high pathologic stage and large tumor size. SIRT7 was also upregulated in human non-small cell lung cancer (NSCLC) cell lines. Furthermore SIRT7-overexpressed A549 (A549-SIRT7) and SIRT7-knocked down H292 (H292-shSIRT7) human NSCLC cell lines were established. Using these NSCLC cells and xenograft mouse models, it was revealed that SIRT7 overexpression markedly promoted growth and G1 to S cell cycle phase transition as well as migration, invasion and distant lung metastasis in A549 NSCLC cells, whereas SIRT7 knockdown suppressed these processes in H292 NSCLC cells. Mechanistically, in A549 NSCLC cells, SIRT7 overexpression significantly activated not only protein kinase B (AKT) signaling but also extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. SIRT7 overexpression also significantly downregulated cyclin-dependent kinase (CDK) inhibitors including p21 and p27 as well as upregulated cyclins including cyclin D1 and cyclin E1, and CDKs including CDK2 and CDK4. Notably, the epithelial-mesenchymal transition (EMT) process of A549 NSCLC cells was facilitated by SIRT7 overexpression, as evidenced by E-cadherin epithelial marker downregulation and mesenchymal markers (N-cadherin, vimentin, Snail and Slug) upregulation. In addition, SIRT7 knockdown in H292 NSCLC cells exhibited the opposite regulatory effects. Moreover, inhibition of AKT signaling abated the promoting effects of SIRT7 in NSCLC cell proliferation and EMT progression. The present data indicated that SIRT7 accelerated human NSCLC cell growth and metastasis possibly by promotion of G1 to S-phase transition and EMT through modulation of the expression of G1-phase checkpoint molecules and EMT markers as well as activation of AKT and ERK1/2 signaling. SIRT7 could be an innovative potential target for human NSCLC therapy.

Downregulation of circular RNA circPVT1 restricts cell growth of hepatocellular carcinoma through downregulation of Sirtuin 7 via microRNA-3666

Circular RNAs (circRNAs) have been identified recently as pivotal regulators in the development and progression of cancers, generally by acting as competing endogenous RNAs of microRNAs (miRNAs) to regulate gene expression. The dysregulation of circRNAs in hepatocellular carcinoma (HCC) has attracted much attention, but the precise role of circRNAs in HCC remains largely unknown. In this study, we aimed to investigate the potential role of circular RNA PVT1 (circPVT1), a newly identified cancer-related circRNA, in HCC. Herein, we found that circPVT1 expression was significantly upregulated in HCC tissues and cell lines. Knockdown of circPVT1 significantly reduced the growth and colony formation, and increased cell apoptosis, of HCC cells. Our results further identified circPVT1 as a sponge for miR-3666. Knockdown of circPVT1 significantly increased miR-3666 expression in HCC cells. Moreover, miR-3666 expression was significantly downregulated in HCC tissues and was inversely correlated with circPVT1 expression. In addition, the overexpression of miR-3666 inhibited the growth of HCC cells by targeting Sirtuin 7 (SIRT7). Notably, miR-3666 inhibition or SIRT7 overexpression partially reversed the circPVT1 knockdown-mediated inhibitory effect on HCC cell growth. Overall, these results demonstrate that downregulation of circPVT1 represses HCC cell growth by upregulating miR-3666 to inhibit SIRT7, suggesting circPVT1 as a potential therapeutic target for HCC. Our study highlights the involvement of circPVT1/miR-3666/SIRT7 in regulating HCC cell growth.

Clinicopathological and molecular analysis of SIRT7 in hepatocellular carcinoma

Sirtuin 7 (SIRT7) is a NAD+ (nicotinamide adenine dinucleotide) dependent deacetylase that is reported to contribute to tumour growth and invasion by selectively acting on histone H3K18. It is overexpressed in several cancers including hepatocellular carcinoma (HCC). In this study, we investigated the relationship between SIRT7 expression, proliferation (Ki-67 index) in human HCC tissues, and patient prognosis. We analysed 219 HCC samples obtained retrospectively, for clinicopathological features, and with immunohistochemistry. SIRT7 overexpression was observed in 73 cases (33%) and correlated with vascular invasion and poor differentiation of HCC. Ki-67 labelling index was observed to be significantly higher in SIRT7 overexpressing cases. Interestingly, the Ki-67 labelling index was higher in SIRT7 overexpressing cases regardless of the differentiation status of HCC. Multivariate analysis demonstrated SIRT7 overexpression as an independent factor predictive of poor prognosis (p=0.016). In vitro, SIRT7 knockdown led to reduced growth in cells and resulted in a lower percentage of G0/G1 cells compared to controls. In addition, the ratio of apoptotic cells following sorafenib treatment was significantly higher in SIRT7 knockdown cells than control cells (p=0.040), implying that SIRT7 knockdown potentiated the effect of sorafenib. In conclusion, our study showed that overexpression of SIRT7 was associated with increased proliferative activity in HCC and predictive of poor prognosis. In addition, our in vitro model showed that SIRT7 knockdown was associated with reduced proliferation, and suggested abrogation of SIRT7 may potentiate the effect of sorafenib. Therefore, we propose that SIRT7 expression by HCC may be used as a prognostic biomarker, and that SIRT7 may be a potential target for new therapeutic modalities.

Associations of sirtuins with clinicopathological variables and prognosis in human ovarian cancer

Ovarian cancer (OC) is the fifth most frequent cause of cancer-associated mortality worldwide, and is accompanied by asymptomatic progression. Sirtuins (SIRTs) are a family of nicotinamide adenine dinucleotide-dependent protein deacetylases, comprising seven members (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7). Accumulating evidence has demonstrated that SIRTs act as prognostic estimators in certain types of cancer such as lung cancer, prostate cancer, gastric cancer, breast cancer and colorectal cancer. However, it remains unknown whether individual SIRTs can serve as independent prognostic factors in OC. In the present study, the Kaplan-Meier plotter online database was utilized to examine the prognostic values of SIRT mRNA expression in patients with OC. The results demonstrated that the overexpression of SIRT3, SIRT5, SIRT6 and SIRT7 mRNAs was associated with a good prognosis in patients, whereas elevated mRNA levels of SIRT1 and SIRT4 indicated poor survival in patients with OC. In addition, among the favorable predictors, SIRT3, SIRT5, SIRT6 and SIRT7 overexpression were associated with overall survival (OS), according to clinical characteristics, such as histological classification, clinical stage, pathology grade, drug therapy and tumor protein p53 mutation status in patients with OC. Similarly, SIRT4 mRNA overexpression was associated with poor OS in pathological grade III cancer. High SIRT1 and SIRT4 expression were associated with unfavorable OS at all clinical stages. Furthermore, SIRT1 and SIRT4 were negatively associated with OS in drug-treated patients. In summary, the present study demonstrated that the SIRT family is associated with the prognosis of human OC, suggesting that individual SIRTs may also act as prognostic predictors in patients.

SIRT7 depletion inhibits cell proliferation and androgen-induced autophagy by suppressing the AR signaling in prostate cancer

BACKGROUND

Sirtuin-7 (SIRT7) is associated with the maintenance of tumorigenesis. However, its functional roles and oncogenic mechanisms in prostate cancer (PCa) are poorly understood. Here, we investigated the roles and underlying molecular mechanisms of SIRT7 in PCa cell growth and androgen-induced autophagy.

METHODS

The LNCap and 22Rv1 PCa cell lines were subjected to quantitative reverse transcription (RT)-PCR to characterize their genes encoding SIRT7, AR, and SMAD4. The proteins produced from these genes were quantified by western blotting and immunoprecipitation analysis. SIRT7-depleted cells were produced by transfection with plasmid vectors bearing short hairpin RNAs against SIRT7. The proliferation of each cell line was assessed by CCK8 and EdU assays. Autophagic flux was tracked by mRFP-GFP-LC3 adenovirus under an immunofluorescence microscope. Apoptosis was evaluated by flow cytometry. Tumors were induced in mouse axillae by injection of the cell lines into mice. Tumor morphology was examined by immunohistochemistry and relative tumor growth and metastases were compared by a bioluminescence-based in vivo imaging system.

RESULTS

SIRT7 depletion significantly inhibited cell proliferation, androgen-induced autophagy, and invasion in LNCap and 22Rv1 cells (in vitro) and mouse xenograft tumors induced by injection of these cells (in vivo). SIRT7 knockdown also increased the sensitivity of PCa cells to radiation. Immunohistochemical analysis of 93 specimens and bioinformatic analysis revealed that SIRT7 expression was positively associated with androgen receptor (AR). Moreover, the AR signal pathway participated in SIRT7-mediated regulation of PCa cell proliferation, autophagy, and invasion. SIRT7 depletion downregulated the AR signal pathway by upregulating the level of SMAD4 protein in PCa cells.

CONCLUSION

SIRT7 plays an important role in the development and progression of human PCa and may be a promising prognostic marker for prostate cancer.

Reversal of ciprofloxacin-induced testosterone reduction by probiotic microbes in mouse testes

CPFX is a highly effective antibiotic, but it has been reported to significantly impair both testicular function and structure in rats. In this study, we assessed reversal of CPFX-induced variation in mice testicular structure and testosterone synthesis by probiotic microbes in the infected model and normal model. We detected testicular weight, testicular structure and Leydig cell variables in numbers. We detected the levels of serum testosterone and steroidogenic enzymes, as well as DBC1, Sirt1, NF-κB, and related redox state and inflammatory response in the testes. The results showed that probiotic microbes had significantly elevated serum testosterone levels and steroidogenic enzymes, higher Sirt1, anti-oxidative enzymes and anti-inflammatory cytokine expression, and lower NF-κB, DBC1, oxidative damage, pro-inflammatory cytokine expression. The results suggest that the testis-protective, antiinflammatory and antioxidation effects of probiotics largely resulted from its ability to decrease oxidative stress and preserve antioxidant activity by stabilizing antioxidant defense systems, reducing oxidative damage and inflammatory response.

Identification of gene co-expression modules and hub genes associated with lymph node metastasis of papillary thyroid cancer

Papillary thyroid cancer (PTC) is the most prevalent histological type among thyroid cancers, and some patients are at a high risk for recurrent disease or even death. Identification for the potential biomarkers of PTC may contribute to early discovery of recurrence and treatment. In The Cancer Genome Atlas (TCGA) database, we obtained the information of RNA sequence data and clinical characteristics of PTC. Weighted gene co-expression network analysis (WGCNA) was performed to construct gene co-expression networks and investigate the relationship between modules and clinical traits. Finally, we constructed 16 co-expression modules in 10,428 genes, and three key modules (darkturquoise, lightyellow, and red) associated with tumor N grade were identified. The results of functional annotation indicated that the darkturquoise module was primarily enriched in the regulation of the extracellular matrix (ECM), collagen metabolism, and cell adhesion, the lightyellow module was primarily enriched in the mitochondrial function regulation and energy synthesis, and the red module was primarily enriched in the process of cell junction, apoptosis, and inflammatory response, suggesting their significant role in the progression of PTC. In addition, the hub genes in the three modules were identified and screened for differentially expressed genes (DEGs). Relapse-free survival analyses found that 11 genes (KCNQ3, MET, FN1, ITGA3, RUNX1, ITGA2, PERP, GCSH, FAAH, NGFRAP1, and HSPA5) may play a pivotal role in PTC relapse. In general, our research revealed the key co-expression modules and identified several prognostic biomarkers, which provides some new insights into the lymph node metastasis of PTC.

Association and clinicopathologic significance of p38MAPK-ERK-JNK-CDC25C with polyploid giant cancer cell formation

BACKGROUND

We previously showed that cobalt chloride (CoCl₂) induction of polyploid giant cancer cells (PGCCs) was characterized by abnormal cell cycle-related protein expression and G2/M arrest. The role of the p38MAPK-ERK-JNK signaling pathway in cell cycle regulation has been reported, but the mechanism by which p38MAPK-ERK-JNK regulates PGCCs formation remains unclear. This study examined p38MAPK-ERK-JNK-CDC25C expression in PGCCs and their daughter and control cells and assessed the clinicopathological significance of p38MAPK, ERK, JNK, and CDC25C expression in human ovarian and breast cancers.

METHODS

CoCl₂ was used to induce the formation of PGCCs in HEY and BT-549 cells. Western blotting and immunocytochemical staining were used to compare the expression and subcellular localization of p38MAPK, ERK, JNK, and CDC25C in the control group and CDC25C knockdown before and after CoCl₂ treatment. The specific combination of p38MAPK and ERK with pCDC25C-Ser216 was detected by immunoprecipitation. In addition, p38MAPK, ERK, JNK, and CDC25C immunohistochemical staining were performed to compare the clinicopathologic significances in 81 cases of ovarian cancer tissue, including 20 cases of primary breast cancer with lymph node metastasis (group I), and their corresponding metastatic lymph nodes (group II), 31 cases of primary breast cancer without metastasis (group III), and 10 cases of benign breast tumors (group IV). Breast tumor tissue from 229 was divided into two groups: 167 cases of primary invasive breast cancer (group 1) and 62 cases of lymph node metastatic breast cancer (group 2).

RESULTS

Compared to the control cells, p38MAPK and JNK expression were higher and CDC25C expression was lower in CoCl₂-treated cells. Moreover, ERK displayed a trend of increased expression in HEY PGCCs and decreased expression in BT-549 PGCCs. p38MAPK and ERK regulated CDC25C by phosphorylating the CDC25C-Ser216 site and participated in the G2/M phase transition. Immunohistochemical (IHC) analysis of the ovarian tumor tissues showed significant positive staining rates of p38MAPK (P = 0.001), ERK (P = 0.002), JNK (P = 0.000), and CDC25C (P = 0.000) among the four groups. In breast tumor tissues, the overall expression in p38MAPK (P = 0.029), ERK (P = 0.002), JNK (P = 0.013), and CDC25C (P = 0.001) also differed significantly between the two groups.

CONCLUSION

The p38MAPK-ERK-JNK signaling pathway was involved in cell cycle progression and the formation of PGCCs by regulation of CDC25C.

METTL7B promotes migration and invasion in thyroid cancer through epithelial-mesenchymal transition

Thyroid cancer is associated with one of the most malignant endocrine tumors. However, molecular mechanisms underlying thyroid tumorigenesis and progression remain unclear. In order to investigate these mechanisms, we performed whole-transcriptome sequencing, which indicated that a differentially expressed gene, METTL7B, was highly expressed in thyroid cancers. We analyzed METTL7B expression using TCGA and performed qRT-PCR on tissue samples. Moreover, an analysis of clinicopathological characteristics revealed a positive correlation between METTL7B and lymph node metastasis. A series of in vitro experiments indicated that METTL7B enhanced migration and invasion of thyroid carcinoma cells. Further studies revealed that METTL7B may enhance TGF-β1-induced epithelial-mesenchymal transition (EMT). Our results indicate that METTL7B may promote metastasis of thyroid cancer through EMT and may therefore be considered as a potential biomarker for the diagnosis and prognosis of thyroid carcinoma.