γ-Glutamyl cyclotransferase contributes to tumor progression in high grade serous ovarian cancer by regulating epithelial-mesenchymal transition via activating PI3K/AKT/mTOR pathway

A comprehensive overview of ovarian cancer stem cells: correlation with high recurrence rate, underlying mechanisms, and therapeutic opportunities

Ovarian cancer is one of the most lethal gynecological malignancies, with a recurrence rate of 70-80%, particularly in patients diagnosed at advanced stages (stage III or IV), where the five-year survival rate falls below 30%. A key driver of this recurrence is the presence of cancer stem cells (CSCs), which exhibit resistance to chemotherapy and possess the capacity for self-renewal, plasticity, and tumor regeneration. The tumor microenvironment (TME) plays a crucial role in maintaining ovarian cancer stem cells (OCSCs) by providing nutrient and oxygen gradients, extracellular matrix (ECM) interactions, immune cell modulation, and support from cancer-associated fibroblasts (CAFs). CAFs secrete growth factors, cytokines, and ECM components that create a pro-tumorigenic niche, promoting CSC maintenance, invasion, and chemoresistance. Additionally, dysregulation of critical signaling pathways, including WNT, NOTCH, PI3K/AKT/mTOR, TGF-β, JAK/STAT, Hedgehog, NF-κB, and Hippo, supports CSC stemness, plasticity, maintenance, and adaptability, thereby increasing their survival and progression. Numerous inhibitors targeting these pathways have shown promise in preclinical studies. This review discusses the molecular mechanisms underlying CSC-mediated recurrence in ovarian cancer and highlights emerging therapeutic strategies. Particular emphasis is placed on the potential of combination therapies involving routine platinum or taxane based regimens with OCSC inhibitors to overcome chemoresistance, reduce recurrence rates, and improve survival outcomes for patients with advanced-stage ovarian cancer.

GGCT participates in the malignant process of hepatocellular cancer cells by regulating the PTEN/PI3K/AKT pathway through binding to EZH2

BACKGROUND

γ-Glutamylcyclotransferase (GGCT) is implicated in multiple types of cancer diseases. Nevertheless, the roles and relevant mechanisms of GGCT in hepatocellular carcinoma (HCC) remain vague.

METHODS

GGCT expression in HCC and its effect on patient survival curve in HCC were evaluated utilizing the UALCAN database, along with western blot. CCK-8, EdU, and wound healing, together with transwell and western blot assays were adopted to assess the capabilities of cells to proliferate, migrate, invade, and epithelial-mesenchymal transition (EMT). Cell apoptosis was appraised utilizing TUNEL as well as western blot. Glycolysis was measured by western blot and kits. Enhancer of zeste homolog 2 (EZH2) expression in HCC cells was detected by western blot. Co-IP verified the combination of GGCT and EZH2. Moreover, PI3K/AKT pathway-related proteins were assessed employing western blot.

RESULTS

GGCT expression was conspicuously upregulated in HCC samples and HCC cells. GGCT silencing repressed HuH-7 cell proliferative, invasive, and migratory capabilities as well as EMT, whereas facilitated cell apoptosis. In addition, GGCT silencing inhibited PTEN/PI3K/AKT pathway-mediated glycolysis. EZH2 was highly expressed in HCC cells and the interaction of GGCT and EZH2 was verified. Overexpression of EZH2 reversed the effects of GGCT silencing on HuH-7 cell proliferation, migration, invasion, cell apoptosis, and glycolysis. Moreover, the PTEN inhibitor SF1670 reversed the effects of GGCT silencing and EZH2 overexpression on the glycolysis and malignant process in HuH-7 cells.

CONCLUSION

In conclusion, GGCT silencing restrained the proliferation and metastasis, and promoted apoptotic levels of HCC cells via regulating PTEN/PI3K/AKT pathway-mediated glycolysis, which might offer a prospective candidate in treating HCC.

Gamma-glutamyl cyclotransferase, a molecule identified from the invasive front of follicular thyroid carcinoma, is useful for differential diagnosis of follicular thyroid tumors

We aimed to establish a useful molecular marker for differentiating between follicular thyroid carcinoma (FTC) and follicular adenoma (FA). RNA was extracted from the invasive front and paired tumor center tissues from three FTC cases using laser microdissection for cDNA microarray analysis, revealing high expression of gamma-glutamyl cyclotransferase (GGCT) in the invasive front. Subsequently, immunohistochemical (IHC) staining of GGCT was performed with formalin-fixed paraffin-embedded (FFPE) sections of FTC (n = 32), FA (n = 64), and follicular tumor of uncertain malignant potential (FT-UMP, n = 5). The GGCT expression score (range: 0-300) was calculated by multiplying the intensity score (0-3) and percentage of positive cells. The Ki-67 labeling index was also assessed in 20 FTC and 25 FA cases from the same cohort. The GGCT expression score was higher in FTC than in FA (118.5 ± 51.4 vs. 57.3 ± 34.7, P < 0.0001). With the GGCT expression score, using a cutoff value of 101.1, the differentiation between FTC and FA was possible with a sensitivity of 68.8 % and specificity of 87.5 % (AUC = 0.832). With the Ki-67 labeling index, applying a cutoff value of 4.0 %, the distinction between FTC and FA resulted in a sensitivity of 50.0 % and specificity of 80.0 % (AUC = 0.677). The GGCT expression score was positively related to the Ki-67 labeling index in the FTC cases. (Spearman's ρ = 0.5293, P = 0.0164). Therefore, GGCT is a potential marker for differentiating FTC from FA. The GGCT expression of FTC may be indicative of its invasive and proliferative activity.

The GGCT and REST positive feedback loop promotes tumor growth in Glioma

BACKGROUND

γ-Glutamylcyclotransferase (GGCT), an enzyme crucial in glutathione metabolism, has emerged as a participant in tumorigenesis. The present study is designed to elucidate the biological role and molecular mechanisms underlying GGCT in glioma.

METHODS

Gene Expression Profiling Interactive Analysis (GEPIA), Chinese Glioma Genome Atlas (CGGA), and PrognoScan online databases were utilized to examine the expressions and clinical prognosis of GGCT and REST in glioma. Cell Counting Kit-8 (CCK-8), Transwell, Wound healing, and Flow cytometric assays, and RNA-sequencing analysis were employed to uncover the molecular role of GGCT and REST. Prediction of Differentially expressed microRNA (DE-miRNAs) and miRNAs targeting GGCT 3' Untranslated Region (UTR) was performed using miRanda online datasets. Finally, Real time-quantitative Polymerase Chain Reaction (RT-qPCR), western blot and dual luciferase reporter gene activity analysis were employed to confirm a positive feedback loop involving GGCT/REST/miR-34a-5p in glioma cells.

RESULTS

High expression of GGCT was correlated with poor prognosis in glioma. GGCT silencing demonstrated inhibitory effects on the proliferation, migration, and induction of apoptosis in T98G and U251 cells. Mechanistically, GGCT downregulated REST expression and modulated cancer-associated pathways in glioma cells. High expression of REST was associated with poor prognosis in glioma. In vitro and in vivo experiments showed that REST overexpression restored the repression of proliferation, invasion, migration, and xenograft tumor formation induced by GGCT knockdown. Furthermore, the study uncovered that REST inhibited miR-34a-5p mRNA expression, and miR-34a-5p suppressed GGCT expression by targeting its 3'UTR, forming a positive regulatory loop in glioma. Notably, the inhibitor of miR-34a-5p restored the role of REST silencing in decreasing GGCT expression in glioma cells.

CONCLUSIONS

GGCT/REST/miR-34a-5p axis holds promising potential as a therapeutic target, offering a potential breakthrough in the treatment of glioma.

Comprehensive transcriptome and scRNA-seq analyses uncover the expression and underlying mechanism of SYNJ2 in papillary thyroid carcinoma

Synaptojanin 2 (SYNJ2) has crucial role in various tumors, but its role in papillary thyroid carcinoma (PTC) remains unexplored. This study first detected SYNJ2 protein expression in PTC using immunohistochemistry method and further assessed SYNJ2 mRNA expression through mRNA chip and RNA sequencing data and its association with clinical characteristics. Additionally, KEGG, GSVA, and GSEA analyses were conducted to investigate potential biological functions, while single-cell RNA sequencing data were used to explore SYNJ2's underlying mechanisms in PTC. Meanwhile, immune infiltration status in different SYNJ2 expression groups were analyzed. Besides, we investigated the immune checkpoint gene expression and implemented drug sensitivity analysis. Results indicated that SYNJ2 is highly expressed in PTC (SMD = 0.66 [95% CI: 0.17-1.15]) and could distinguish between PTC and non-PTC tissues (AUC = 0.74 [0.70-0.78]). Furthermore, the study identified 134 intersecting genes of DEGs and CEGs, mainly enriched in the angiogenesis and epithelial-mesenchymal transition (EMT) pathways. Subsequent analysis showed the above pathways were activated in PTC epithelial cells. PTC patients with high SYNJ2 expression showed higher sensitivity to the six common drugs. Summarily, SYNJ2 may promote PTC progression through angiogenesis and EMT pathways. High SYNJ2 expression is associated with better response to immunotherapy and chemotherapy.

Mechanisms of Yiai Fuzheng formula in the treatment of triple-negative breast cancer based on UPLC-Q-Orbitrap-HRMS, network pharmacology, and experimental validation

Ethnopharmacological relevance

Yiai Fuzheng formula (YAFZF), as a Traditional Chinese Medicine (TCM) prescription, has been used widely at Zhongnan Hospital of Wuhan University for its therapeutic effects and high safety on triple-negative breast cancer (TNBC).

Objective

In this study, we employed ultra-high-performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry (UPLC-Q-Orbitrap-HRMS), network pharmacology, and experimental validation to elucidate the underlying action mechanism of YAFZF in the treatment of TNBC.

Methods

The key active ingredients in YAFZF were analyzed using UPLC-Q-Orbitrap-HRMS, and then the potential components, target genes and signalling pathways of YAFZF were predicted using the network pharmacological method. We then used molecular docking to visualize the combination characteristics between major active components and macromolecules in the crucial pathway. In vitro experiments were conducted to investigate the inhibitory effects of YAFZF treatment on the cell viability, invasion, and migration of 4T1 and MDA-MB-231 cells. The xenograft TNBC models were constructed using female Balb/c mice, and their body weights, tumour volumes, and weights were monitored during YAFZF treatment. Quantitative real-time PCR (qRT-PCR), Hematoxylin-eosin (HE), immunohistochemistry (IHC) staining, Western blot (WB), and terminal deoxynucleotidyl transferase (TdT)-dUTP nick-end labeling (TUNEL) staining were used for further experimental validation.

Results

Based on UPLC-Q-Orbitrap-HRMS and network pharmacology analysis, 6 major bioactive components and 153 intersecting genes were obtained for YAFZF against TNBC. Functional enrichment analysis identified that the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signalling pathway might be the mechanism of action of YAFZF in the treatment of TNBC. Molecular docking results suggested that the main active compounds in YAFZF had strong binding energies with the proteins in the PI3K/Akt pathway. In vitro experiments showed that YAFZF inhibited the cell viability, invasion, and migration abilities of TNBC cells. Animal experiments confirmed that YAFZF treatment suppressed tumour cell proliferation and increased apoptotic cells. PCR, HE, WB, and IHC results indicated that YAFZF could suppress xenograft tumour metastases by inhibiting the PI3K/AKT/mTOR pathway regulating the epithelial-mesenchymal transition (EMT) process.

Conclusion

YAFZF therapy showed its potential for reducing proliferation, invasion, and migration abilities, increasing apoptosis of TNBC cells. Furthermore, YAFZF treated TNBC by inhibiting xenograft tumour distant metastases via the regulation of EMT by the PI3K/Akt/mTOR pathway, suggesting that it may be useful as an adjuvant treatment.

Identified γ-glutamyl cyclotransferase (GGCT) as a novel regulator in the progression and immunotherapy of pancreatic ductal adenocarcinoma through multi-omics analysis and experiments

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is renowned for its formidable and lethal nature, earning it a notorious reputation among malignant tumors. Due to its challenging early diagnosis, high malignancy, and resistance to chemotherapy drugs, the treatment of pancreatic cancer has long been exceedingly difficult in the realm of oncology. γ-Glutamyl cyclotransferase (GGCT), a vital enzyme in glutathione metabolism, has been implicated in the proliferation and progression of several tumor types, while the biological function of GGCT in pancreatic ductal adenocarcinoma remains unknown.

METHODS

The expression profile of GGCT was validated through western blotting, immunohistochemistry, and RT-qPCR in both pancreatic cancer tissue samples and cell lines. Functional enrichment analyses including GSVA, ssGSEA, GO, and KEGG were conducted to explore the biological role of GGCT. Additionally, CCK8, Edu, colony formation, migration, and invasion assays were employed to evaluate the impact of GGCT on the proliferation and migration abilities of pancreatic cancer cells. Furthermore, the LASSO machine learning algorithm was utilized to develop a prognostic model associated with GGCT.

RESULTS

Our study revealed heightened expression of GGCT in pancreatic cancer tissues and cells, suggesting an association with poorer patient prognosis. Additionally, we explored the immunomodulatory effects of GGCT in both pan-cancer and pancreatic cancer contexts, found that GGCT may be associated with immunosuppressive regulation in various types of tumors. Specifically, in patients with high expression of GGCT in pancreatic cancer, there is a reduction in the infiltration of various immune cells, leading to poorer responsiveness to immunotherapy and worse survival rates. In vivo and in vitro assays indicate that downregulation of GGCT markedly suppresses the proliferation and metastasis of pancreatic cancer cells. Moreover, this inhibitory effect appears to be linked to the regulation of GGCT on c-Myc. A prognostic model was constructed based on genes derived from GGCT, demonstrating robust predictive ability for favorable survival prognosis and response to immunotherapy.

Identification of c-Met as a novel target of γ-glutamylcyclotransferase

γ-Glutamylcyclotransferase (GGCT) is highly expressed in multiple types of cancer tissues and its knockdown suppresses the growth of cancer cells in vitro and in vivo. Although GGCT is a promising target for cancer therapy, the mechanisms underlying the antitumor effects remain unclear. The knockdown of GGCT inhibited the MEK-ERK pathway, and activated the tumor suppressor retinoblastoma gene (RB) at the protein level in cancer cell lines. c-Met was down-regulated by the knockdown of GGCT in cancer cells and its overexpression attenuated the dephosphorylation of RB and cell cycle arrest induced by the knockdown of GGCT in lung cancer A549 cells. STAT3 is a transcription factor that induces c-Met expression. STAT3 phosphorylation and its nuclear expression level were decreased in GGCT-depleted A549 and prostate cancer PC3 cells. The simultaneous knockdown of AMPK and GGCT restored the down-regulated expression of c-Met, and attenuated the dephosphorylation of STAT3 and MEK-ERK-RB induced by the knockdown of GGCT in PC3 cells. An intraperitoneal injection of a GGCT inhibitor decreased c-Met protein expression in a mouse xenograft model of PC3 cells. These results suggest that the knockdown of GGCT activates the RB protein by inhibiting the STAT3-c-Met-MEK-ERK pathway via AMPK activation.

Imputation of single-cell transcriptome data enables the reconstruction of networks predictive of breast cancer metastasis

Single-cell transcriptome data provide a unique opportunity to explore the gene networks of a particular cell type. However, insufficient capture rate and high dimensionality of single-cell RNA sequencing (scRNA-seq) data challenge cell-type-specific gene network (CGN) reconstruction. Here, we demonstrated that the imputation of scRNA-seq data enables reconstruction of CGNs by effective retrieval of gene functional associations. We reconstructed CGNs for seven primary and nine metastatic breast cancer cell lines using scRNA-seq data with imputation. Key genes for primary or metastatic cell lines were prioritized based on network centrality measures and CGN hub genes that were presumed to be the major determinant of cell type characteristics. To identify novel genes in breast cancer metastasis, we used the average rank difference of centrality between the primary and metastatic cell lines. Genes predicted using CGN centrality analysis were more enriched for known breast cancer metastatic genes than those predicted using differential expression. The molecular chaperone CCT2 was identified as a novel gene for breast metastasis during knockdown assays of several candidate genes. Overall, our study demonstrated an effective CGN reconstruction technique with imputation of scRNA-seq data and the feasibility of identifying key genes for particular cell subsets using single-cell network analysis.

MiR-205-5p/GGCT Attenuates Growth and Metastasis of Papillary Thyroid Cancer by Regulating CD44

Papillary thyroid cancer (PTC) remains the most common endocrine malignancy, despite marked achieves in recent decades, and the mechanisms underlying the pathogenesis and progression for PTC are incompletely elucidated. Accumulating evidence show that γ-glutamylcyclotransferase (GGCT), an enzyme participating in glutathione homeostasis and is elevated in multiple types of tumors, represents an attractive therapeutic target. Using bioinformatics, immunohistochemistry, qRT-PCR, and Western blot assays, we found that GGCT expression was upregulated in PTC and correlated with more aggressive clinicopathological characteristics and worse prognosis. GGCT knockdown inhibited the growth and metastasis ability of PTC cells both in vitro and in vivo and reduced the expression of mesenchymal markers (N-cadherin, CD44, MMP2, and MMP9) while increasing epithelial marker (E-cadherin) in PTC cells. We confirmed binding of microRNA-205-5p (miR-205-5p) on the 3'-UTR regions of GGCT by dual-luciferase reporter assay and RNA-RNA pull-down assay. Delivery of miR-205-5p reversed the pro-malignant capacity of GGCT both in vitro and in vivo. Lastly, we found that GGCT interacted with and stabilized CD44 in PTC cells by co-immunoprecipitation and immunohistochemistry assays. Our findings illustrate a novel signaling pathway, miR-205-5p/GGCT/CD44, that involves in the carcinogenesis and progression of PTC. Development of miR-205-mimics or GGCT inhibitors as potential therapeutics for PTC may have remarkable applications.

Oxidative and Antioxidative Status Expressed as OSI Index and GSH/GSSG Ratio in Children with Bone Tumors after Anticancer Therapy Completion

Aims. There are no data on the redox status of children with bone tumors in complete disease remission. Therefore, the presented study examined the reduced/oxidized glutathione (GSH/GSSG) ratio, total oxidant capacity (TOC) and total antioxidant capacity (TAC) values as well as the oxidative stress index (OSI) for assessing alterations in the oxidant/antioxidant balance in 35 children with osteosarcoma or Ewing’s sarcoma after anticancer therapy completion (median 14 months) compared with a control group. Methods. GSH, GSSG, TOC, TAC concentrations and bone alkaline phosphatase (BALP) activity were evaluated by immunoenzymatic (ELISA) and enzymatic methods. Results. We found no differences in serum BALP activity between all survivors with bone tumors and the control group. Patients with osteosarcoma after anticancer therapy completion had significantly higher values of TAC, GSH and the GSH/GSSG ratio as well as GSSG than healthy subjects. In patients with Ewing’s sarcoma, we found significantly higher values of TOC concentration compared with healthy children. In addition, survivors with Ewing’s sarcoma had higher TOC concentrations and OSI index values (p < 0.01), but a lower GSH/GSSG ratio (p < 0.05) than survivors with osteosarcoma. A positive correlation between TOC and the post-therapy period was observed in survivors. Conclusions. We found that in survivors with bone tumors, a disturbed balance between prooxidants and antioxidants persists after the completion of anticancer treatment. Moreover, an increased TOC value together with the post-therapy period may suggest increasing oxidative processes in survivors with bone tumors after treatment. Further observations will allow assessment of the relationship between the oxidant/antioxidant status and the predisposition of survivors to bone neoplastic disease recurrence.

Does the Urinary Proteome Reflect ccRCC Stage and Grade Progression?

Due its ability to provide a global snapshot of kidney physiology, urine has emerged as a highly promising, non-invasive source in the search for new molecular indicators of disease diagnosis, prognosis, and surveillance. In particular, proteomics represents an ideal strategy for the identification of urinary protein markers; thus, a urinomic approach could also represent a powerful tool in the investigation of the most common kidney cancer, which is clear cell Renal Cell Carcinoma (ccRCC). Currently, these tumors are classified after surgical removal using the TNM and nuclear grading systems and prognosis is usually predicted based upon staging. However, the aggressiveness and clinical outcomes of ccRCC remain heterogeneous within each stratified group, highlighting the need for novel molecular indicators that can predict the progression of these tumors. In our study, we explored the association between the urinary proteome and the ccRCC staging and grading classification. The urine proteome of 44 ccRCC patients with lesions of varying severity was analyzed via label-free proteomics. MS data revealed several proteins with altered abundance according to clinicopathological stratification. Specifically, we determined a panel of dysregulated proteins strictly related to stage and grade, suggesting the potential utility of MS-based urinomics as a complementary tool in the staging process of ccRCC.

Non-linear relationship between gamma-glutamyl transferase and type 2 diabetes mellitus risk: secondary analysis of a prospective cohort study

OBJECTIVE

To investigate the association between gamma-glutamyl transferase (GGT) and type 2 diabetes mellitus (T2DM) risk.

METHODS

This was a secondary analysis based on a publicly available DRYAD dataset that included 15 444 study participants that received medical examinations at a single centre in Japan between 2004 and 2015. Crude, minimally-adjusted and fully-adjusted regression models were used to evaluate the relationship between GGT levels and T2DM risk.

RESULTS

The study participants (mean ± SD age of 43.72 ± 8.90 years; 8415 of 15 444 [54.49%] were male) were followed-up for a median of 1968 days (5.39 years). After adjusting for potential covariates, a non-linear relationship between the baseline GGT level and T2DM incidence was observed. The inflection point for T2DM risk was 10 IU/l GGT; below this point, the T2DM incidence increased by 1.18-fold per unit change in GGT. Above this point, the association between GGT and the incidence rate of T2DM became nonsignificant.

CONCLUSION

Baseline GGT exhibited a non-linear association with T2DM incidence. Elevated GGT levels should be incorporated into routine screening for individuals at high risk of T2DM, allowing for early intervention targeting GGT to potentially reduce T2DM-related morbidity.

Identification of U83836E as a γ-glutamylcyclotransferase inhibitor that suppresses MCF7 breast cancer xenograft growth

γ-Glutamylcyclotransferase (GGCT) is involved in glutathione homeostasis, in which it catalyzes the reaction that generates 5-oxoproline and free amino acids from γ-glutamyl peptides. Increasing evidence shows that GGCT has oncogenic functions and is overexpressed in various cancer tissues, and that inhibition of GGCT activity exerts anticancer effects in vitro and in vivo. Here, we demonstrate that U83836E ((2R)-2-[[4-(2,6-dipyrrolidin-1-ylpyrimidin-4-yl)piperazin-1-yl]methyl]-3,4-dihydro-2,5,7,8,-tetramethyl-2H-1-benzopyran-6-ol, dihydrochloride), a lazaroid that inhibits lipid peroxidation, inhibits GGCT enzymatic activity. U83836E was identified from a high-throughput screen of low molecular weight compounds using a fluorochrome-conjugated GGCT probe. We directly quantified that U83836E specifically inhibited GGCT by measuring the product of a fluorochrome-conjugated GGCT substrate assay, and showed that U83836E inhibited GGCT activity in extracts of NIH3T3 cells overexpressing GGCT. Moreover, U83836E significantly inhibited tumor growth in a xenograft model that used immunodeficient mice orthotopically inoculated with MCF7 human breast cancer cells. These results indicate that U83836E may be a useful GGCT inhibitor for the development of potential cancer therapeutics.

γ-Glutamylcyclotransferase, a novel regulator of HIF-1α expression, triggers aerobic glycolysis

Metabolic reprogramming leading to aerobic glycolysis, termed the "Warburg effect," is a critical property of cancer cells. However, the precise mechanisms underlying this phenomenon are not fully understood. A growing body of evidence indicates that γ-glutamylcyclotransferase (GGCT), an enzyme involved in glutathione homeostasis that is highly expressed in many types of cancer, represents a promising therapeutic target. In this study, we identified GGCT as a novel regulator of hypoxia-inducible factor-1α (HIF-1α), a transcription factor that plays a role in hypoxia adaptation promoting aerobic glycolysis. In multiple human cancer cell lines, depletion of GGCT downregulated HIF-1α at the mRNA and protein levels. Conversely, in NIH3T3 mouse fibroblasts, overexpression of GGCT upregulated HIF-1α under normoxia. Moreover, depletion of GGCT downregulated HIF-1α downstream target genes involved in glycolysis, whereas overexpression of GGCT upregulated those genes. Metabolomic analysis revealed that modulation of GGCT expression induced a metabolic switch from the citric acid cycle to glycolysis under normoxia. In addition, we found that GGCT regulates expression of HIF-1α protein via the AMPK-mTORC1-4E-BP1 pathway in PC3 cells. Thus GGCT regulates the expression of HIF-1α in cancer cells, causing a switch to glycolysis.

The Communication Between the PI3K/AKT/mTOR Pathway and Y-box Binding Protein-1 in Gynecological Cancer

Studies of the mechanistic (mammalian) target of rapamycin inhibitors (mTOR) represent a step towards the targeted treatment of gynecological cancers. It has been shown that women with increased levels of mTOR signaling pathway targets have worse prognosis compared to women with normal mTOR levels. Yet, targeting mTOR alone has led to unsatisfactory outcomes in gynecological cancer. The aim of our review was therefore to provide an overview of the most recent clinical results and basic findings on the interplay of mTOR signaling and cold shock proteins in gynecological malignancies. Due to their oncogenic activity, there are promising data showing that mTOR and Y-box-protein 1 (YB-1) dual targeting improves the inhibition of carcinogenic activity. Although several components differentially expressed in patients with ovarian, endometrial, and cervical cancer of the mTOR were identified, there are only a few investigated downstream actors in gynecological cancer connecting them with YB-1. Our analysis shows that YB-1 is an important player impacting AKT as well as the downstream actors interacting with mTOR such as epidermal growth factor receptor (EGFR), Snail or E-cadherin.

γ-Glutamyl cyclotransferase contributes to endometrial carcinoma malignant progression and upregulation of PD-L1 expression during activation of epithelial-mesenchymal transition

Recent increases in the incidence of endometrial carcinoma represent a significant risk to women's health. We found that γ-glutamyl cyclotransferase (GGCT) was significantly up-regulated in endometrial carcinoma tissues and cells, which suggested that it may be a potential target for treatment of endometrial carcinoma. Furthermore, the impact of GGCT on proliferation, migration, and invasion of endometrial carcinoma has been demonstrated in vitro and in vivo using GGCT silencing and overexpression techniques. In addition, the epithelial-mesenchymal transition (EMT) was significantly inhibited in response to GGCT knockdown, which indicated that GGCT may contribute endometrial carcinoma malignancy during activation of the EMT. We also found that GGCT regulated PD-L1 expression during EMT activation. Furthermore, co-culture of endometrial carcinoma cells with CD8⁺ T lymphocytes showed that downregulation of PD-L1 expression following GGCT knockdown contributed to the killing activity of CD8⁺ T lymphocytes on endometrial carcinoma cells. In conclusion, our study showed that GGCT contributed to malignant progression and upregulation of PD-L1 expression of endometrial carcinoma, and may be a potential target for treatment of endometrial carcinoma.

Inhibition of EP2/EP4 prostanoid receptor-mediated signaling suppresses IGF-1-induced proliferation of pancreatic cancer BxPC-3 cells via upregulating γ-glutamyl cyclotransferase expression

Inhibition of prostaglandin E₂ signaling via EP2/EP4 prostanoid receptors suppresses Insulin-like growth factor (IGF)-1-induced proliferation of pancreatic cancer BxPC-3 cells. To better understand the mechanism of EP2/EP4 signaling for controlling cell proliferation, we performed metabolome analyses in BxPC-3 cells treated with IGF-1 alone or IGF-1 plus EP2/EP4 inhibitors. These analyses revealed increased g-aminobutyric acid and 5-oxoproline production following the addition of EP2/EP4 inhibitors to IGF-1-treated cells. The expression of a 5-oxoproline-catalyzing enzyme, γ-glutamylcyclotransferase (GGCT), was also upregulated by IGF-1 treatment and further enhanced by the addition of EP2/EP4 inhibitors. Knockdown of GGCT expression resulted in the loss of suppressive effects of EP2/EP4 inhibitors on IGF-1-induced BxPC-3 cell proliferation, whereas GGCT overexpression repressed the basal proliferation of BxPC-3 cells but did not affect the suppressive effects of EP2/EP4 inhibitors. To summarize, we propose a role for EP2/EP4 signaling in regulating IGF-1-induced cell proliferation, in which EP2/EP4 signaling represses IGF-1-induced GGCT expression, which mediates and whose amount controls a branch of IGF-1 signaling to promote cell proliferation via extracellular signal-regulated kinase phosphorylation.

IMPDH2 promotes colorectal cancer progression through activation of the PI3K/AKT/mTOR and PI3K/AKT/FOXO1 signaling pathways

Background

Inosine 5′-monophosphate dehydrogenase type II (IMPDH2) was originally identified as an oncogene in several human cancers. However, the clinical significance and biological role of IMPDH2 remain poorly understood in colorectal cancer (CRC).

Methods

Quantitative real-time polymerase chain reaction (qPCR), western blotting analysis, the Cancer Genome Atlas (TCGA) data mining and immunohistochemistry were employed to examine IMPDH2 expression in CRC cell lines and tissues. A series of in-vivo and in-vitro assays were performed to demonstrate the function of IMPDH2 and its possible mechanisms in CRC.

Results

IMPDH2 was upregulated in CRC cells and tissues at both mRNA and protein level. High IMPDH2 expression was closely associated with T stage, lymph node state, distant metastasis, lymphovascular invasion and clinical stage, and significantly correlated with poor survival of CRC patients. Further study revealed that overexpression of IMPDH2 significantly promoted the proliferation, invasion, migration and epithelial-mesenchymal transition (EMT) of CRC cells in vitro and accelerated xenograft tumour growth in nude mice. On the contrary, knockdown of IMPDH2 achieved the opposite effect. Gene set enrichment analysis (GSEA) showed that the gene set related to cell cycle was linked to upregulation of IMPDH2 expression. Our study verified that overexpressing IMPDH2 could promote G1/S phase cell cycle transition through activation of PI3K/AKT/mTOR and PI3K/AKT/FOXO1 pathways and facilitate cell invasion, migration and EMT by regulating PI3K/AKT/mTOR pathway.

Conclusions

These results suggest that IMPDH2 plays an important role in the development and progression of human CRC and may serve as a novel prognostic biomarker and therapeutic target for CRC.

Lysine demethylase 2A promotes the progression of ovarian cancer by regulating the PI3K pathway and reversing epithelial‑mesenchymal transition

Metastasis is the most common cause of death in ovarian cancer patients but remains largely untreated. Epithelial‑mesenchymal transition (EMT) is critical for the conversion of early‑stage ovarian tumors into metastatic malignancies. Thus, investigating the signaling pathways promoting EMT may identify potential targets for the treatment of metastatic ovarian cancer. Lysine demethylase 2A (KDM2A), also known as FBXL11 and JHDM1A, is a histone H3 lysine 36 (H3K36) demethylase that regulates EMT and the metastasis of ovarian cancer. However, the function and underlying mechanisms of EMT suppression in ovarian cancer have not been thoroughly elucidated to date. In the present study, we used Gene Expression Omnibus (GEO) databases to determine that KDM2A is significantly upregulated in human ovarian cancers. KDM2A expression was assessed by immunohistochemistry of epithelial ovarian cancer (EOC) borderline ovarian tumors and normal ovary tissues. Seven fresh EOC tissues and 3 fresh normal ovary tissues were collected for western blot analysis. Kaplan‑Meier survival curves were constructed to identify genes related to EOC prognosis from the TCGA data portal. Stable KDM2A‑knockdown cell lines were established to study the biological functions and underlying mechanisms of KDM2A in EMT in vitro. GEO database analysis revealed that KDM2A was highly upregulated in EOC tissues; this analysis was accompanied by immunochemistry and western blot analysis using samples of human tissues. High expression of KDM2A was associated with poor survival in EOC patients. KDM2A knockdown promoted apoptosis and suppressed the proliferation, migration and invasion of tumor cells in vitro. EMT and the PI3K/AKT/mTOR signaling pathway were suppressed in KDM2A‑silenced cells. Inactivation of the PI3K/AKT/mTOR signaling pathway in A2780 cells induced EMT inhibition. Our data revealed that KDM2A functions as a tumor oncogene, and the downregulation of KDM2A expression regulates EMT and EOC progression, providing a valuable prognostic marker and potential target for the treatment of EOC patients.

Mechanisms of Tumor Growth Inhibition by Depletion of γ-Glutamylcyclotransferase (GGCT): A Novel Molecular Target for Anticancer Therapy

γ-Glutamylcyclotransferase (GGCT), which is one of the major enzymes involved in glutathione metabolism, is upregulated in a wide range of cancers—glioma, breast, lung, esophageal, gastric, colorectal, urinary bladder, prostate, cervical, ovarian cancers and osteosarcoma—and promotes cancer progression; its depletion leads to the suppression of proliferation, invasion, and migration of cancer cells. It has been demonstrated that the suppression or inhibition of GGCT has an antitumor effect in cancer-bearing xenograft mice. Based on these observations, GGCT is now recognized as a promising therapeutic target in various cancers. This review summarizes recent advances on the mechanisms of the antitumor activity of GGCT inhibition.