Expression of pyruvate dehydrogenase is an independent prognostic marker in gastric cancer

Cuproptosis-related gene DLAT is a biomarker of the prognosis and immune microenvironment of gastric cancer and affects the invasion and migration of cells

OBJECTIVE

Cuproptosis is a novel cell death dependent on mitochondrial respiration and regulated by copper. This study aimed to investigate the cuproptosis-related gene DLAT potential value in gastric cancer (GC).

METHODS

Bioinformatics was used to analyze DLAT expression. DLAT expression in GC cell lines was detected using qRT-PCR. Cell proliferation ability was assessed using CCK8 and cell cycle assay. Cell migration and invasion were assessed using wound healing and transwell assay. A prognostic assessment was performed through survival and Cox regression analysis. DLAT protein expression was analyzed through HPA immunohistochemistry. Biological functions and processes were analyzed through GO and KEGG enrichment analysis and PPI. Correlation with immune cell infiltration and immune checkpoint genes was analyzed for DLAT.

RESULTS

DLAT expression was upregulated in GC tissues and cells and correlated with shorter survival for patients. Age, gender, histological typing, lymph node metastasis, and distant metastasis were identified as independent prognostic factors affecting OS in GC. DLAT protein was upregulated in GC. The biological functions and pathways enriched in DLAT were mainly linked to mitochondrial respiration and the TCA cycle. The expression of DLAT was found to be positively correlated with the infiltration of Th and Th2 immune cells and only positively correlated with the expression of the BTN2A1 immune checkpoint gene.

CONCLUSION

DLAT has the potential to serve as a prognostic assessment factor in GC. The expression of DLAT was correlated with immune infiltration and tumor immune escape, providing a new target for immunotherapy of GC.

Role of microRNA-363 during tumor progression and invasion

Recent progresses in diagnostic and therapeutic methods have significantly improved prognosis in cancer patients. However, cancer is still considered as one of the main causes of human deaths in the world. Late diagnosis in advanced tumor stages can reduce the effectiveness of treatment methods and increase mortality rate of cancer patients. Therefore, investigating the molecular mechanisms of tumor progression can help to introduce the early diagnostic markers in these patients. MicroRNA (miRNAs) has an important role in regulation of pathophysiological cellular processes. Due to their high stability in body fluids, they are always used as the non-invasive markers in cancer patients. Since, miR-363 deregulation has been reported in a wide range of cancers, we discussed the role of miR-363 during tumor progression and metastasis. It has been reported that miR-363 has mainly a tumor suppressor function through the regulation of transcription factors, apoptosis, cell cycle, and structural proteins. MiR-363 also affected the tumor progression via regulation of various signaling pathways such as WNT, MAPK, TGF-β, NOTCH, and PI3K/AKT. Therefore, miR-363 can be introduced as a probable therapeutic target as well as a non-invasive diagnostic marker in cancer patients.

Mitochondrial Proteins as Metabolic Biomarkers and Sites for Therapeutic Intervention in Primary and Metastatic Cancers

Accelerated aerobic glycolysis is one of the main metabolic alterations in cancer, associated with malignancy and tumor growth. Although glycolysis is one of the most studied properties of tumor cells, recent studies demonstrate that oxidative phosphorylation (OxPhos) is the main ATP provider for the growth and development of cancer. In this last regard, the levels of mRNA and protein of OxPhos enzymes and transporters (including glutaminolysis, acetate and ketone bodies catabolism, free fatty acid β-oxidation, Krebs Cycle, respiratory chain, phosphorylating system- ATP synthase, ATP/ADP translocator, Pi carrier) are altered in tumors and cancer cells in comparison to healthy tissues and organs, and non-cancer cells. Both energy metabolism pathways are tightly regulated by transcriptional factors, oncogenes, and tumor-suppressor genes, all of which dictate their protein levels depending on the micro-environmental conditions and the type of cancer cell, favoring cancer cell adaptation and growth. In the present review paper, variation in the mRNA and protein levels as well as in the enzyme/ transporter activities of the OxPhos machinery is analyzed. An integral omics approach to mitochondrial energy metabolism pathways may allow for identifying their use as suitable, reliable biomarkers for early detection of cancer development and metastasis, and for envisioned novel, alternative therapies.

Identification of cuproptosis-related molecular subtypes and a novel predictive model of COVID-19 based on machine learning

Background

To explicate the pathogenic mechanisms of cuproptosis, a newly observed copper induced cell death pattern, in Coronavirus disease 2019 (COVID-19).

Methods

Cuproptosis-related subtypes were distinguished in COVID-19 patients and associations between subtypes and immune microenvironment were probed. Three machine algorithms, including LASSO, random forest, and support vector machine, were employed to identify differentially expressed genes between subtypes, which were subsequently used for constructing cuproptosis-related risk score model in the GSE157103 cohort to predict the occurrence of COVID-19. The predictive values of the cuproptosis-related risk score were verified in the GSE163151 cohort, GSE152418 cohort and GSE171110 cohort. A nomogram was created to facilitate the clinical use of this risk score, and its validity was validated through a calibration plot. Finally, the model genes were validated using lung proteomics data from COVID-19 cases and single-cell data.

Results

Patients with COVID-19 had higher significantly cuproptosis level in blood leukocytes compared to patients without COVID-19. Two cuproptosis clusters were identified by unsupervised clustering approach and cuproptosis cluster A characterized by T cell receptor signaling pathway had a better prognosis than cuproptosis cluster B. We constructed a cuproptosis-related risk score, based on PDHA1, PDHB, MTF1 and CDKN2A, and a nomogram was created, which both showed excellent predictive values for COVID-19. And the results of proteomics showed that the expression levels of PDHA1 and PDHB were significantly increased in COVID-19 patient samples.

Conclusion

Our study constructed and validated an cuproptosis-associated risk model and the risk score can be used as a powerful biomarker for predicting the existence of SARS-CoV-2 infection.

Differential expression of pyruvate dehydrogenase E1A and its inactive phosphorylated form among breast cancer subtypes

AIMS

Pyruvate dehydrogenase E1A (PDH-E1A) is one of the key regulators of metabolic pathways that determines pyruvate entry into the citric acid cycle or glycolysis. When PDH-E1A is phosphorylated (P-PDH-E1A), it loses its activity, shifting the metabolism towards glycolysis. Breast cancer (BC) is a highly heterogeneous disease by which different breast cancer subtypes acquire distinct metabolic profiles. Assessing PDH-E1A and P-PDH-E1A expressions among BC subtypes might reveal their association with the distinct molecular profiles of BCs.

METHODS

The expressions of PDH-E1A and P-PDH-E1A were investigated in BC cell lines and 115 BC tissues using Western blot and immunohistochemistry, respectively. Besides, PDHE1A mRNA expression was assessed in 1084 BCE patients' transcriptomics data retrieved from Cancer Genome Atlas database. Statistical analyses were performed to assess the correlation of PDH-E1A and P-PDH-E1A expressions with patients' clinicopathological characteristics. Kaplan-Meier method was used to evaluate their prognostic value.

KEY FINDINGS

Multivariate analysis revealed a significant association between PDH-E1A/P-PDH-E1A expressions and the molecular subtype, histological type, and tumor size of breast cancer tissues. The hormonal receptors (ER and PR), HER-2, and Ki67 protein expressions were significantly associated with PDH-E1A and P-PDH-E1A protein expressions. Similar findings were observed when PDHA1 mRNA expression was assessed. The increased protein expression of PDH-E1A could be an independent prognostic factor for unfavorable overall survival (OS). In contrast, high PDHA1 mRNA expression had better OS.

SIGNIFICANCE

This study revealed the differential expression of PDH-E1A and P-PDH-E1A among breast cancer subtypes and suggested PDH-E1A expression as a prognostic factor for BC patients' OS.

Microenvironmental control of glucose metabolism in tumors by regulation of pyruvate dehydrogenase

During malignant progression cancer cells undergo a series of changes, which promote their survival, invasiveness and metastatic process. One of them is a change in glucose metabolism. Unlike normal cells, which mostly rely on the tricarboxylic acid cycle (TCA), many cancer types rely on glycolysis. Pyruvate dehydrogenase complex (PDC) is the gatekeeper enzyme between these two pathways and is responsible for converting pyruvate to acetyl-CoA, which can then be processed further in the TCA cycle. Its activity is regulated by PDP (pyruvate dehydrogenase phosphatases) and PDHK (pyruvate dehydrogenase kinases). Pyruvate dehydrogenase kinase exists in 4 tissue specific isoforms (PDHK1-4), the activities of which are regulated by different factors, including hormones, hypoxia and nutrients. PDHK1 and PDHK3 are active in the hypoxic tumor microenvironment and inhibit PDC, resulting in a decrease of mitochondrial function and activation of the glycolytic pathway. High PDHK1/3 expression is associated with worse prognosis in patients, which makes them a promising target for cancer therapy. However, a better understanding of PDC's enzymatic regulation in vivo and of the mechanisms of PDHK-mediated malignant progression is necessary for the design of better PDHK inhibitors and the selection of patients most likely to benefit from such inhibitors.

MiR-370 functions as oncogene in melanoma by direct targeting pyruvate dehydrogenase B

BACKGROUND

Accumulating evidence has shown that miR-370 play an important role in the development and progression of tumor. However, the role of miR-370 in melanoma remains largely unknown. The present study is designed to investigate the function of miR-370 in melanoma and to explore the molecular mechanism underlying its function.

MATERIALS AND METHODS

The expression level of miR-370 was detected in melanoma tissues and cell lines by real-time quantitative polymerase chain reaction (qRT-PCR). The effect of overexpression of miR-370 on in vitro cell proliferation, apoptosis, invasion as well as glyclolysis was examined. Western blotting analysis was used to detect the influence of miR-370 on the expression of target genes, and Pearson analysis was used to calculate the correlation between the expression of targets gene and miR-370 in melanoma tissues.

RESULTS

Our study showed that miR-370 was upregulated in melanoma tissues compared with non-cancerous tissues (P<0.01). In addition, the expression of miR-370 in melanoma cell lines was also significantly higher (P<0.01). Enforced expression of miR-370 promotes melanoma cell proliferation, inhibits apoptosis and enhances invasion and glycolysis and led to downregulation of the PDHB protein. Moreover, the expression level of miR-370 in melanoma tissues showed inverse relationship with the expression level of PDHB protein.

CONCLUSIONS

In conclusion, our findings suggested that miR-370 represents a potential oncogenic miRNA and plays an important role in melanoma progression by directly targeting PDHB.

miR-146b-5p regulates cell growth, invasion, and metabolism by targeting PDHB in colorectal cancer

MiRNA have been found to play a role in a plethora of cellular processes of cancer cells such as cell apoptosis, cell proliferation, invasion, migration metabolism and stem cell differentiation. Dysregulation of miR-146b-5p has been documented in a variety of human malignancies. However, the biological functions and molecular mechanisms of miR-146b-5p in ovarian cancer remain unknown. In this study, our results show that miR-146b-5p was unregulated in colorectal cancer (CRC) tissues compared with the adjacent non-cancerous tissues. Ectopic overexpression of miR-146b-5p in CRC promoted cell growth, invasion and glycolysis, while knockdown of miR-146b-5p inhibited the growth, invasion and glycolysis of CRC cells. The oncogenic effect of miR-146b-5p is also confirmed in vivo. Mechanically, miR-146b-5p targets the 3'-UTR of pyruvate dehydrogenase B (PDHB) and exerts oncogenic effect. Overexpression of PDHB abolished the oncogenic effects of miR-146b-5p on the growth, invasion and glycolysis of CRC cells. Taken together, our results show that miR-146b-5p is an oncogenic miRNA in CRC which exerts its effect by directly targeting PDHB.

Prognostic value of diffuse versus intestinal histotype in patients with gastric cancer: a systematic review and meta-analysis

BACKGROUND

There are two distinct types of gastric carcinoma (GC), intestinal, more frequently sporadic and linked to environmental factors, and diffuse (undifferentiated) that is highly metastatic and characterized by rapid disease progression and a poor prognosis. However, there are many conflicting data in the literature concerning the association between histology and prognosis in GC. This meta-analysis was performed to provide demonstration if histology according to Lauren classification is associated with different prognosis in patients with GC.

METHODS

We searched PubMed, the Cochrane Library, SCOPUS, Web of Science, CINAHL, and EMBASE for all eligible studies. The combined hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) in terms of overall survival (OS) were evaluated.

RESULTS

A total of 73 published studies including 61,468 patients with GC were included in this meta-analysis. Our analysis indicates that GC patients with diffuse-type histology have a worst prognosis than those with intestinal subgroup in all studies (HR 1.23; 95% CI, 1.17-1.29; P<0.0001), in both loco-regional confined (HR 1.21; 95% CI, 1.12-1.30; P<0.0001) and advanced disease (HR 1.25; 95% CI, 1.046-1.50; P=0.014), in Asiatic (HR 1.2; 95% CI, 1.14-1.27; P<0.0001) and Western patients (HR 1.3; 95% CI, 1.19-1.41; P<0.0001), and in those not exposed (HR 1.15; 95% CI, 1.07-1.24; P<0.0001) or exposed (HR 1.27; 95% CI, 1.17-1.37; P<0.0001) to (neo)adjuvant therapy.

CONCLUSIONS

Our results indicated that histology might be a useful prognostic marker for both early and advanced GC patients, with intestinal-type associated with a better outcome. This information could be used for stratification purpose in future clinical trials.

MiR-203 promotes the growth and migration of ovarian cancer cells by enhancing glycolytic pathway

MicroRNAs (miRNAs) play an important role in the tumorigenesis of ovarian cancer. Previously, we have reported the dysregulation of miR-203 in the ovarian cancer tissues. However, the biological functions and molecular mechanisms of miR-203 in ovarian cancer remain unknown. Here, we showed that the expression of miR-203 was increased in ovarian cancer tissues compared with the adjacent non-cancerous tissues and the transcription of miR-203 was inhibited by P53. Forced expression of miR-203 in ovarian cancer promoted cell growth and migration, while depletion of miR-203 inhibited the growth and migration of ovarian cancer cells. In addition, miR-203 promoted the metastasis of ovarian cancer cells in vivo and shorted the survival of the nude mice. Mechanically, miR-203 targeted the 3'-UTR of pyruvate dehydrogenase B (PDHB) and increased the consumption of glucose and the production of lactate. Overexpression of PDHB abolished the oncogenic effects of miR-203 on the growth of ovarian cancer cells. Together, our data suggested the oncogenic roles of miR-203 in ovarian cancer by promoting glycolysis, and miR-203 might be a therapeutic target for ovarian cancer.

Mitochondria in Cancer Energy Metabolism: Culprits or Bystanders?

Cancer is a disease characterized by uncontrolled growth. Metabolic demands to sustain rapid proliferation must be compelling since aerobic glycolysis is the first as well as the most commonly shared characteristic of cancer. During the last decade, the significance of metabolic reprogramming of cancer has been at the center of attention. Nonetheless, despite all the knowledge gained on cancer biology, the field is not able to reach agreement on the issue of mitochondria: Are damaged mitochondria the cause for aerobic glycolysis in cancer? Warburg proposed the damaged mitochondria theory over 80 years ago; the field has been testing the theory equally long. In this review, we will discuss alterations in metabolic fluxes of cancer cells, and provide an opinion on the damaged mitochondria theory.