Downregulation of fatty acid synthase complex suppresses cell migration by targeting phospho-AKT in bladder cancer

Development of a prognostic model for muscle-invasive bladder cancer using glutamine metabolism

BACKGROUND

Muscle-invasive bladder cancer (MIBC) is distinguished by its pronounced invasiveness and unfavorable prognosis. Immunotherapy and targeted therapy have emerged as key treatment options for various types of cancer. Altered metabolism is a defining characteristic of cancer cells, and there is mounting evidence suggesting the important role of glutamine metabolism (GM) in tumor metabolism. Nevertheless, the relationship between GM and clinical outcomes, immune microenvironment, and immunotherapy in MIBC remains unknown.

METHODS

This study employed Mendelian randomization to explore the causal relationship between blood metabolites and bladder tumors. We systematically evaluated 373 glutamine metabolism-related genes and identified prognostic-related genes, leading to the construction of a glutamine-associated prognostic model. Further analysis confirmed the correlation between high and low-risk groups with the tumor microenvironment, immune cell infiltration, and tumor mutation burden. Subsequently, we assessed the relationship between the risk score and the sensitivity to various immunotherapies and anticancer drugs.

RESULTS

We identified 14 blood metabolites at the molecular level that have a causal relationship with bladder tumors. At the gene level, the study discussed differentially expressed GM genes in MIBC. First, we established a risk model predicting overall survival (OS) based on GM genes, confirming its reliable predictive ability in MIBC patients and validated it in a GEO cohort. Additionally, a reliable column line chart was created. Secondly, two distinct molecular subtypes were identified, and the associations between different risk groups and tumor microenvironment and immune infiltration were observed. In addition, the predicted risk values correlated with responses to a broad range of pharmaceutical agents.

CONCLUSION

In summary, we confirmed the causal relationship between blood metabolites and bladder tumors. Furthermore, a risk scoring model related to glutamine metabolism consisting of 9 genes was developed. This model could potentially serve as a useful tool for predicting prognosis and guiding the treatment of MIBC patients.

Evaluation of aliphatic acid metabolism in bladder cancer with the goal of guiding therapeutic treatment

Urothelial bladder cancer (BLCA) is a common internal malignancy with a poor prognosis. The re-programming of lipid metabolism is necessary for cancer cell growth, proliferation, angiogenesis and invasion. However, the role of aliphatic acid metabolism genes in bladder cancer patients has not been explored. The samples’ gene expression and clinicopathological data were obtained from the Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO). Univariate, multivariate, and LASSO Cox regression were used to develop a BLCA prognostic model. GSVA was used to assess function, whereas pRRophetic was used to assess chemotherapeutic drug sensitivity. The twelve-gene signature may define the tumor immune milieu, according to the risk score model. We compared the expression of aliphatic acid metabolism genes in malignant and non-cancerous tissues and chose 90 with a false discovery rate of 0.05 for The Cancer Genome Atlas cohort. The prognostic risk score model can effectively predict BLCA OS. A nomogram including age, clinical T stage, gender, grade, pathological stage, and clinical M stage was developed as an independent BLCA prognostic predictor. The halfmaximal inhibitory concentration (IC50) was used to assess chemotherapeutic medication response. Sorafenib and Pyrimethamine were used to treat patients with low risk scores more sensitively than patients with high risk scores. Immunotherapy candidates with CMS1 exhibited higher risk ratings. The aliphatic acid prognostic risk score model can assess metabolic trends. Clinical stage and molecular subtype may be used to categorize individuals using the risk score.With this new paradigm, future cancer treatment and immunotherapy may be tailored to the patient’s exact requirements.

Identification and validation of a novel signature for prediction the prognosis and immunotherapy benefit in bladder cancer

BACKGROUND

Bladder cancer (BC) is a common urinary tract system tumor with high recurrence rate and different populations show distinct response to immunotherapy. Novel biomarkers that can accurately predict prognosis and therapeutic responses are urgently needed. Here, we aim to identify a novel prognostic and therapeutic responses immune-related gene signature of BC through a comprehensive bioinformatics analysis.

METHODS

The robust rank aggregation was conducted to integrate differently expressed genes (DEGs) in datasets of the Cancer Genome Atlas (TCGA) and the gene expression omnibus (GEO). Lasso and Cox regression analyses were performed to formulate a novel mRNA signature that could predict prognosis of BC patients. Subsequently, the prognostic value and predictive value of the signature was validated with two independent cohorts GSE13507 and IMvigor210. Finally, quantitative Real-time PCR (qRT-PCR) analysis was conducted to determine the expression of mRNAs in BC cell lines (UM-UC-3, EJ-1, SW780 and T24).

RESULTS

We built a signature comprised the eight mRNAs: CNKSR1, COPZ2, CXorf57, FASN, PCOLCE2, RGS1, SPINT1 and TPST1. Our prognostic signature could be used to stratify BC population into two risk groups with distinct immune profile and responsiveness to immunotherapy. The results of qRT-PCR demonstrated that the eight mRNAs exhibited different expression levels in BC cell lines.

CONCLUSION

Our study constructed a convenient and reliable 8-mRNA gene signature, which might provide prognostic prediction and aid treatment decision making of BC patients in clinical practice.

Identification of a novel metabolism-related gene signature associated with the survival of bladder cancer

Background

Bladder cancer (BC) is one of the most common malignancies and has a relatively poor outcome worldwide. In this study, we attempted to construct a novel metabolism-related gene (MRG) signature for predicting the survival probability of BC patients.

Methods

First, differentially expressed MRGs between BC and normal samples were identified and used to construct a protein-protein interaction (PPI) network and perform mutation analysis. Next, univariate Cox regression analysis was utilized to select prognostic genes, and multivariate Cox regression analysis was applied to establish an MRG signature for predicting the survival probability of BC patients. Moreover, Kaplan-Meier (KM) survival analysis and receiver operating characteristic (ROC) analysis were performed to evaluate the predictive capability of the MRG signature. Finally, a nomogram based on the MRG signature was established to better predict the survival of BC.

Results

In the present study, 27 differentially expressed MRGs were identified, most of which presented mutations in BC patients, and LRP1 showed the highest mutation rate. Next, an MRG signature, including MAOB, FASN and LRP1, was established by using univariate and multivariate Cox regression analysis. Furthermore, survival analysis indicated that BC patients in the high-risk group had a dramatically lower survival probability than those in the low-risk group. Finally, Cox regression analysis showed that the risk score was an independent prognostic factor, and a nomogram integrating age, pathological tumor stage and risk score was established and presented good predictive ability.

Conclusion

We successfully constructed a novel MRG signature to predict the prognosis of BC patients, which might contribute to the clinical treatment of BC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09006-w.

Development and validation of a novel lipid metabolism-related gene prognostic signature and candidate drugs for patients with bladder cancer

BACKGROUND

Bladder cancer (BLCA) is a common cancer associated with an unfavorable prognosis. Increasing numbers of studies have demonstrated that lipid metabolism affects the progression and treatment of tumors. Therefore, this study aimed to explore the function and prognostic value of lipid metabolism-related genes in patients with bladder cancer.

METHODS

Lipid metabolism-related genes (LRGs) were acquired from the Molecular Signature Database (MSigDB). LRG mRNA expression and patient clinical data were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Cox regression analysis and least absolute shrinkage and selection operator (LASSO) regression analysis was used to construct a signature for predicting overall survival of patients with BLCA. Kaplan-Meier analysis was performed to assess prognosis. The connectivity Map (CMAP) database was used to identify small molecule drugs for treatment. A nomogram was constructed and assessed by combining the signature and other clinical factors. The CIBERSORT, MCPcounter, QUANTISEQ, XCELL, CIBERSORT-ABS, TIMER and EPIC algorithms were used to analyze the immunological characteristics.

RESULTS

An 11-LRG signature was successfully constructed and validated to predict the prognosis of BLCA patients. Furthermore, we also found that the 11-gene signature was an independent hazardous factor. Functional analysis suggested that the LRGs were closely related to the PPAR signaling pathway, fatty acid metabolism and AMPK signaling pathway. The prognostic model was closely related to immune cell infiltration. Moreover, the expression of key immune checkpoint genes (PD1, CTLA4, PD-L1, LAG3, and HAVCR2) was higher in patients in the high-risk group than in those in the low-risk group. The prognostic signature based on 11-LRGs exhibited better performance in predicting overall survival than conventional clinical characteristics. Five small molecule drugs could be candidate drug treatments for BLCA patients based on the CMAP dataset.

CONCLUSIONS

In conclusion, the current study identified a reliable signature based on 11-LRGs for predicting the prognosis and response to immunotherapy in patients with BLCA. Five small molecule drugs were identified for the treatments of BLCA patients.

Proteomic Profiling of Ectosomes Derived from Paired Urothelial Bladder Cancer and Normal Cells Reveals the Presence of Biologically-Relevant Molecules

Protein content of extracellular vesicles (EVs) can modulate different processes during carcinogenesis. Novel proteomic strategies have been applied several times to profile proteins present in exosomes released by urothelial bladder cancer (UBC) cells. However, similar studies have not been conducted so far on another population of EVs, i.e., ectosomes. In the present study we used a shotgun nanoLC-MS/MS proteomic approach to investigate the protein content of ectosomes released in vitro by T-24 UBC cells and HCV-29 normal ureter epithelial cells. In addition, cancer-promoting effects exerted by UBC-derived ectosomes on non-invasive cells in terms of cell proliferation and migratory properties were assessed. In total, 1158 proteins were identified in T-24-derived ectosomes, while HCV-29-derived ectosomes contained a lower number of 259 identified proteins. Qualitative analysis revealed 938 proteins present uniquely in T-24-derived ectosomes, suggesting their potential applications in bladder cancer management as diagnostic and prognostic biomarkers. In addition, T-24-derived ectosomes increased proliferation and motility of recipient cells, likely due to the ectosomal transfer of the identified cancer-promoting molecules. The present study provided a focused identification of biologically relevant proteins in UBC-derived ectosomes, confirming their role in UBC development and progression, and their applicability for further biomarker-oriented studies in preclinical or clinical settings.

The metabolic landscape of urological cancers: New therapeutic perspectives

Deregulation of cell metabolism is an established cancer hallmark that contributes to tumor initiation and progression, as well as tumor heterogeneity. In solid tumors, alterations in different metabolic pathways, including glycolysis, pentose phosphate pathway, glutaminolysis and fatty acid metabolism, support the high proliferative rates and macromolecule biosynthesis of cancer cells. Despite advances in therapy, urothelial tumors still exhibit high recurrence and mortality rates, especially in advanced stages of disease. These tumors harbor gene mutations and expression patterns which play an important role in metabolic reprogramming. Taking into account the unique metabolic features underlying carcinogenesis in these cancers, new and promising therapeutic targets based on metabolic alterations must be considered. Furthermore, the combination of metabolic inhibitors with conventional targeted therapies may improve effectiveness of treatments. This review will summarize the metabolic alterations present in urological tumors and the results with metabolic inhibitors currently available.

Down-regulation of PKM2 decreases FASN expression in bladder cancer cells through AKT/mTOR/SREBP-1c axis

Fatty acid synthase (FASN) catalyzing the terminal steps in the de novo biogenesis of fatty acids is correlated with low survival and high disease recurrence in patients with bladder cancer. Pyruvate kinase M2 (PKM2) regulates the final step of glycolysis levels and provides a growth advantage to tumors. However, it is unclear whether the change of PKM2 has an effect on FASN and what is the mechanisms underlying. Here we describe a novel function of PKM2 in control of lipid metabolism by mediating transcriptional activation of FASN, showing the reduced expression of sterol regulatory element binding protein 1c (SREBP-1c). We first discovered that PKM2 physically interacts with the SREBP-1c using biochemical approaches, and downregulation of PKM2 reduced the expression of SREBP-1c by inactivating the AKT/mTOR signaling pathway, which in turn directly suppressed the transcription of major lipogenic genes FASN to reduce tumor growths. Furthermore, either PKM2 inhibitor-Shikonin or FASN inhibitor-TVB-3166 alone induced a strong antiproliferative and anticolony forming effect in bladder cancer cell line. The combination of both inhibitors exhibits a super synergistic effect on blocking the bladder cancer cells growth. It provides a new target and scientific basis for the treatment of bladder cancer.

Fatty acid synthase, Her2/neu, and E2F1 as prognostic markers of progression in non-muscle invasive bladder cancer

Non-muscle-invasive bladder cancer (NMIBC) is a heterogeneous disease which has an unpredictable risk of progression to muscle-invasive bladder cancer (MIBC). The selection of patients who may benefit from early radical intervention is a challenge. To define the useful prognostic markers for progression, we analyzed the immunohistochemical expression of fatty acid synthase (FASN), Her2/neu, and E2F1 in 60 cases of NMIBC who underwent TURBT and adjuvant intravesical bacillus-Calmette-Guérin (BCG). Their predicting role for tumor recurrence, progression, recurrence-free survival (RFS) and progression-free survival (PFS) was analyzed. High FASN expression was observed in 56.7% (34/60) of NMIBC cases, and FASN expression was significantly associated with the tumor size, grade, and tumor stage (p = 0.003, p < 0.001, p < 0.0001 respectively). Positive Her2/neu was noted in 18.3% (11/60) of the cases, and its expression was significantly associated with the tumor size, histologic grade, and tumor stage (p = 0.001, p = 0.002, p = 0.011 respectively). High E2F1 expression was detected in 40% of the cases, and it was associated with tumor size, histologic grade, and tumor stage (p < 0.001 for each). Analysis of follow-up period revealed that NMIBC with high FASN, positive Her2/neu, and high E2F1 expression exhibited a potent relation with tumor progression, shorter RFS, and poor PFS. Conclusions: High FASN, Her2/neu, and E2F1 are considered as adverse prognostic factors of tumor recurrence and progression in NMIBC and these patients should be followed carefully. Therefore, we suggest that FASN, Her2/neu, and E2F1 should be considered and evaluated during the selection of the appropriate management strategy for NMIBC patients.

Small interfering RNA-mediated knockdown of fatty acid synthase attenuates the proliferation and metastasis of human gastric cancer cells via the mTOR/Gli1 signaling pathway

Fatty acid synthase (FASN), the main enzyme involved in de novo lipogenesis, is overexpressed in several types of tumor tissues. In addition, it is associated with tumor cell proliferation, metastasis, epithelial-mesenchymal transition (EMT) and a poor prognosis. However, the precise functions and internal mechanisms of FASN with regard to the proliferation, metastasis and EMT in gastric cancer (GC) cells remain elusive. The present study investigated FASN protein expression in 18 randomly selected pairs of GC tumors and matched normal tissues by western blot analysis. FASN-specific small interfering RNA (siRNA) was then transfected into SGC-7901 cells to examine the effect of FASN on proliferation and migration in vitro. Western blotting was used to detect the protein expression of FASN, EMT-related markers and key signaling molecules of the mechanistic target of rapamycin/zinc finger protein GLI1 (mTOR/Gli1) pathway. Reverse transcription-quantitative polymerase chain reaction was conducted to detect the mRNA expression of FASN and EMT-related markers. The FASN level was higher in the GC tissues compared with that in the surrounding normal tissues. Knockdown of FASN suppressed GC cell proliferation and metastasis in vitro. The silencing of FASN expression using siRNA reversed EMT at the protein and mRNA levels and decreased the expression of Gli1 via regulation of AMP-activated protein kinase/mTOR and protein kinase B/mTOR signaling in GC cells. Inhibition of FASN suppresses GC proliferation and metastasis through targeting of the mTOR/Gli1 signaling pathway, indicating that it may serve as a potential target for the treatment of GC.

MicroRNA-1207-5p inhibits hepatocellular carcinoma cell growth and invasion through the fatty acid synthase-mediated Akt/mTOR signalling pathway

Fatty acid synthase (FASN) has emerged as a unique oncologic target for the treatment of cancers, including hepatocellular carcinoma (HCC). However, effective inhibitors of FASN for cancer treatment are lacking. MicroRNAs (miRNAs) have emerged as novel and endogenic inhibitors of gene expression. In the present study, we aimed to investigate the role of miR‑1207‑5p in HCC and the regulation of FASN through miR‑1207‑5p. The expression of miR-1207-5p was markedly reduced in HCC tissues and cell lines as detected with real‑time quantitative polymerase chain reaction (qPCR). Overexpression of miR-1207-5p significantly suppressed the cell growth and invasion of HCC cells. By contrast, inhibition of miR‑1207‑5p exhibited an opposite effect. Bioinformatics analysis showed that FASN is a predicted target of miR‑1207‑5p which was validated by dual‑luciferase reporter assay, qPCR and western blot analysis. Overexpression of miR‑1207‑5p inhibited the Akt/mTOR signalling pathway, and promotion of this pathway was noted following inhibition of miR‑1207‑5p. Rescue experiments showed that the restoration of FASN expression partially reversed the inhibitory effect of miR‑1207‑5p on cell growth, invasion and Akt phosphorylation. In conclusion, our study suggests that miR‑1207‑5p/FASN plays an important role in HCC, and provides novel insight into developing new inhibitors for FASN for therapeutic interventions for HCC.

Metabolic phenotype of bladder cancer

Metabolism of bladder cancer represents a key issue for cancer research. Several metabolic altered pathways are involved in bladder tumorigenesis, representing therefore interesting targets for therapy. Tumor cells, including urothelial cancer cells, rely on a peculiar shift to aerobic glycolysis-dependent metabolism (the Warburg-effect) as the main energy source to sustain their uncontrolled growth and proliferation. Therefore, the high glycolytic flux depends on the overexpression of glycolysis-related genes (SRC-3, glucose transporter type 1 [GLUT1], GLUT3, lactic dehydrogenase A [LDHA], LDHB, hexokinase 1 [HK1], HK2, pyruvate kinase type M [PKM], and hypoxia-inducible factor 1-alpha [HIF-1α]), resulting in an overproduction of pyruvate, alanine and lactate. Concurrently, bladder cancer metabolism displays an increased expression of genes favoring the pentose phosphate pathway (glucose-6-phosphate dehydrogenase [G6PD]) and the fatty-acid synthesis (fatty acid synthase [FASN]), along with a decrease of AMP-activated protein kinase (AMPK) and Krebs cycle activities. Moreover, the PTEN/PI3K/AKT/mTOR pathway, hyper-activated in bladder cancer, acts as central regulator of aerobic glycolysis, hence contributing to cancer metabolic switch and tumor cell proliferation. Besides glycolysis, glycogen metabolism pathway plays a robust role in bladder cancer development. In particular, the overexpression of GLUT-1, the loss of the tumor suppressor glycogen debranching enzyme amylo-α-1,6-glucosidase, 4-α-glucanotransferase (AGL), and the increased activity of the tumor promoter enzyme glycogen phosphorylase impair glycogen metabolism. An increase in glucose uptake, decrease in normal cellular glycogen storage, and overproduction of lactate are consequences of decreased oxidative phosphorylation and inability to reuse glucose into the pentose phosphate and de novo fatty acid synthesis pathways. Moreover, AGL loss determines augmented levels of the serine-to-glycine enzyme serine hydroxymethyltransferase-2 (SHMT2), resulting in an increased glycine and purine ring of nucleotides synthesis, thus supporting cells proliferation. A deep understanding of the metabolic phenotype of bladder cancer will provide novel opportunities for targeted therapeutic strategies.