A novel prognostic marker and immunogenic membrane antigen: prohibitin (PHB) in pancreatic cancer

UBXN1 promotes liver tumorigenesis by regulating mitochondrial homeostasis

BACKGROUND

The maintenance of mitochondrial homeostasis is critical for tumor initiation and malignant progression because it increases tumor cell survival and growth. The molecular events controlling mitochondrial integrity that facilitate the development of hepatocellular carcinoma (HCC) remain unclear. Here, we report that UBX domain-containing protein 1 (UBXN1) hyperactivation is essential for mitochondrial homeostasis and liver tumorigenesis.

METHODS

Oncogene-induced mouse liver tumor models were generated with the Sleeping Beauty (SB) transposon delivery system. Assessment of HCC cell growth in vivo and in vitro, including tumour formation, colony formation, TUNEL and FACS assays, was conducted to determine the effects of UBXN1 on HCC cells, as well as the involvement of the UBXN1-prohibitin (PHB) interaction in mitochondrial function. Coimmunoprecipitation (Co-IP) was used to assess the interaction between UBXN1 and PHB. Liver hepatocellular carcinoma (LIHC) datasets and HCC patient samples were used to assess the expression of UBXN1.

RESULTS

UBXN1 expression is commonly upregulated in human HCCs and mouse liver tumors and is associated with poor overall survival in HCC patients. UBXN1 facilitates the growth of human HCC cells and promotes mouse liver tumorigenesis driven by the NRas/c-Myc or c-Myc/shp53 combination. UBXN1 interacts with the inner mitochondrial membrane protein PHB and sustains PHB expression. UBXN1 inhibition triggers mitochondrial damage and liver tumor cell apoptosis.

CONCLUSIONS

UBXN1 interacts with PHB and promotes mitochondrial homeostasis during liver tumorigenesis.

The function of prohibitins in mitochondria and the clinical potentials

Prohibitins (PHBs) are a class of highly evolutionarily conserved proteins that widely distribute in prokaryotes and eukaryotes. PHBs function in cell growth and proliferation or differentiation, regulating metabolism and signaling pathways. PHBs have different subcellular localization in eukaryotes, but they are mainly located in mitochondria. In the mitochondria, PHBs stabilize the structure of the mitochondrial membrane and regulate mitochondrial autophagy, mitochondrial dynamics, mitochondrial biogenesis and quality control, and mitochondrial unfolded protein response. PHBs has shown to be associated with many diseases, such as mitochondria diseases, cancers, infectious diseases, and so on. Some molecule targets of PHBs can interfere with the occurrence and development of diseases. Therefore, this review clarifies the functions of PHBs in mitochondria, and provides a summary of the potential values in clinics.

Phospholipase A/acyltransferase 4 is a prognostic biomarker and correlated with immune infiltrates in pancreatic cancer

Background

Phospholipase A/acyltransferase (PLAAT) family exhibits O- and N-acyltransferase activity and biosynthesize N-acylated ethanolamine phospholipids. Previously, PLAAT4 was seen as a tumor suppressor, but the exact function of PLAAT4 in pancreatic cancer was still unknown. In this study, we investigated the relationship of PLAAT4 and pancreatic cancer.

Methods

Using the data from the cancer genome atlas (TCGA), Genotype-Tissue Expression (GTEx) database and Gene Expression Omnibus (GEO) datasets we compared the expression of PLAAT4 in normal and tumor tissues and analyzed the connections between PLAAT4 and several clinicopathological factors. Further, we conducted Gene ontology (GO) analysis, Gene set enrichment analysis (GSEA), single sample gene set enrichment analysis (ssGSEA) and estimate analysis to explore the association between PLAAT4 and biological function and immune infiltration. In addition, Kaplan-Meier (KM) analysis, univariate and multivariate Cox analysis were used to explore the association between PLAAT4 and prognosis. In addition, we plotted a nomogram according to the multivariate cox analysis visualizing the predictive ability of PLAAT4 on prognosis. In addition, we explore the influence of PLAAT4 on malignant behaviors of the pancreatic cancer cells in vitro.

Results

After comparing the expression of PLAAT4 in normal and tumor tissues, we found that the expression of PLAAT4 was significantly high in pancreatic ductal adenocarcinoma (PDAC) samples. In addition, the results of GO and GSEA found that the expression of PLAAT4 was related to cell cycle checkpoints, M phase, regulation by p53, cell cycle mitotic and etc. Further, ssGSEA has shown that PLAAT4 was positively related to the abundance of aDC, Th1 cells, Th2 cells and negatively related to the Th17 cells. Subsequently, KM analysis, univariate and multivariate Cox analysis were used to analyze the correlation between PLAAT4 and prognosis. Additionally, we found that higher expression of PLAAT4 was related to T stage, N stage, histologic grade, etc (P < 0.05) and has a significant correlation with poor Overall Survival (OS), Disease-Specific Survival (DSS) and Progression-Free Interval (PFI). At last, we proved that PLAAT4 contributed to the malignant behaviors of the pancreatic cancer cells.

Conclusion

This study indicated PLAAT4 as a novel prognostic biomarker and an important molecular that mediated immune response in pancreatic cancer.

Sensitive electrochemical immunosensor to detect prohibitin 2, a potential blood cancer biomarker

Blood cancers are difficult to cure completely and frequently show a poor prognosis. Recently, prohibitin 2 (PHB2) has been shown to be a potential biomarker for blood cancers. Sandwich ELISA can be used as a reference method for quantitative analysis of PHB2; however, ELISA can be challenging for early diagnosis and continuous monitoring method due to the need for large sample volumes (25 μL <), technical expertise, complex procedure, relative high cost, and non-portability. Thus, this study developed a sensitive and time efficient electrochemical immunosensor for detecting PHB2 from a blood cancer patient. It is a simple and portable platform consisting of a disposable electrode and blood sample volume of 4 μL. The sensor uses a gold nanostructured electrode and square wave voltammetry (SWV) measurement of a horseradish peroxidase (HRP) label to amplify the electrochemical signal. The immunosensor could quantitatively detect PHB2 with high sensitivity (limit of detection [LoD] = 0.04 ng/mL) and satisfactory reproducibility (relative standard deviation [RSD] <5.2%). The sensor achieved an LoD of 0.63 ng/mL with satisfactory recovery (89.1-104.7%) and reproducibility (RSD <6.4%) with PHB2 spiked into white blood cell (WBC) lysates. When the sensor was compared to a reference ELISA to determine the PHB2 concentrations in WBC lysate samples from healthy patients and those with blood cancer, the correlation coefficient (R²) was 0.996. A 3.3-fold difference was detected in the measured PHB2 concentration between blood cancer patients and healthy individuals. Accordingly, this study suggests a sensitive and accurate analytical method for quantitatively detecting the PHB2 in blood samples.

Peptidylarginine Deiminase Inhibitor Application, Using Cl-Amidine, PAD2, PAD3 and PAD4 Isozyme-Specific Inhibitors in Pancreatic Cancer Cells, Reveals Roles for PAD2 and PAD3 in Cancer Invasion and Modulation of Extracellular Vesicle Signatures

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies with limited survival rate. Roles for peptidylarginine deiminases (PADs) have been studied in relation to a range of cancers with roles in epigenetic regulation (including histone modification and microRNA regulation), cancer invasion, and extracellular vesicle (EV) release. Hitherto though, knowledge on PADs in PDAC is limited. In the current study, two PDAC cell lines (Panc-1 and MiaPaCa-2) were treated with pan-PAD inhibitor Cl-amidine as well as PAD2, PAD3, and PAD4 isozyme-specific inhibitors. Effects were assessed on changes in EV signatures, including EV microRNA cargo (miR-21, miR-126, and miR-221), on changes in cellular protein expression relevant for pancreatic cancer progression and invasion (moesin), for mitochondrial housekeeping (prohibitin, PHB), and gene regulation (deiminated histone H3, citH3). The two pancreatic cancer cell lines were found to predominantly express PAD2 and PAD3, which were furthermore expressed at higher levels in Panc-1, compared with MiaPaCa-2 cells. PAD2 isozyme-specific inhibitor had the strongest effects on reducing Panc-1 cell invasion capability, which was accompanied by an increase in moesin expression, which in pancreatic cancer is found to be reduced and associated with pancreatic cancer aggressiveness. Some reduction, but not significant, was also found on PHB levels while effects on histone H3 deimination were variable. EV signatures were modulated in response to PAD inhibitor treatment, with the strongest effects observed for PAD2 inhibitor, followed by PAD3 inhibitor, showing significant reduction in pro-oncogenic EV microRNA cargo (miR-21, miR-221) and increase in anti-oncogenic microRNA cargo (miR-126). While PAD2 inhibitor, followed by PAD3 inhibitor, had most effects on reducing cancer cell invasion, elevating moesin expression, and modulating EV signatures, PAD4 inhibitor had negligible effects and pan-PAD inhibitor Cl-amidine was also less effective. Compared with MiaPaCa-2 cells, stronger modulatory effects for the PAD inhibitors were observed in Panc-1 cells, which importantly also showed strong response to PAD3 inhibitor, correlating with previous observations that Panc-1 cells display neuronal/stem-like properties. Our findings report novel PAD isozyme regulatory roles in PDAC, highlighting roles for PAD isozyme-specific treatment, depending on cancer type and cancer subtypes, including in PDAC.

Wilms Tumor: Challenges and Newcomers in Prognosis

Wilms tumor is the most common renal tumor of childhood. It is a biologically and morphologically diverse entity, with ongoing studies contributing to our understanding of the pathobiology of various subgroups of patients with Wilms tumor. The interplay of histologic examination and molecular interrogation is integral in prognostication and direction of therapy. This review provides an overview of some of the challenging aspects and pitfalls in pathologic assessment of Wilms tumor, along with discussion of current and up-and-coming markers of biological behavior with prognostic significance.

Aberrant Expression of Prohibitin Is Related to Prognosis of Nasal Extranodal Natural Killer/T Cell Lymphoma, Nasal Type

INTRODUCTION

Nasal extranodal natural killer (NK)/T cell lymphoma, nasal type (ENKTCL) is a high-grade Epstein-Barr virus (EBV)-associated malignancy with poor outcomes. There are few biomarkers for the accurate diagnosis and prognostic prediction of the disease. The aim of this study was to investigate the clinicopathological significance of prohibitin (PHB) expression in nasal ENKTCL.

METHODS

The expression level of PHB was detected via immunohistochemical staining in 49 nasal ENKTCL tissues and age- and sex-matched controls of 30 nasal mucosa-reactive lymphoid hyperplasia (NRLH) tissues. The correlations between the PHB expression and clinicopathological features of patients with nasal ENKTCL were evaluated.

RESULTS

The results indicated a significantly decreased expression of PHB in nasal ENKTCL tissues compared with in NRLH tissues. Low-level PHB expression was significantly associated with younger age and fever (p = 0.008 and 0.018, respectively). The Kaplan-Meier analysis showed that the cytoplasm expression level of PHB in nasal ENKTCL was inversely related to overall survival (p = 0.046).

CONCLUSIONS

PHB may be a potential diagnostic marker and prognostic predictor of nasal ENKTCL.

Glucose starvation-induced oxidative stress causes mitochondrial dysfunction and apoptosis via Prohibitin 1 upregulation in human breast cancer cells

In recent years there has been an upsurge in research focusing on reprogramming cancer cells through understanding of their metabolic signatures. Alterations in mitochondrial bioenergetics and impaired mitochondrial function may serve as effective targeting strategies especially in triple-negative breast cancers (TNBCs) where hormone receptors and endocrine therapy are absent. Glucose starvation (GS) of MDA-MB-231 and MCF-7 breast cancer cells showed decrease in mitochondrial Oxygen Consumption Rate (OCR), which was rescuable to control level through addition of exogenous antioxidant N-Acetyl Cysteine (NAC). Mechanistically, GS led to increase in mitochondrial ROS and upregulation of the pleiotropic protein, Prohibitin 1 (PHB1), leading to its dissociation from Dynamin-related protein 1 (DRP1), perturbance of mitochondrial membrane potential (MMP) and triggering of the apoptosis cascade. PHB1 also reduced the invasive and migratory potential of both cell lines. We emphasize that glucose starvation remarkably sensitized the highly glycolytic metastatic TNBC cell line, MDA-MB-231 to apoptosis and decreased its migratory potential. Based on our findings, additional TNBC cell lines can be evaluated and a nutritional paradigm be proposed for anticancer therapy.

Prohibitins: A Critical Role in Mitochondrial Functions and Implication in Diseases

Prohibitin 1 (PHB1) and prohibitin 2 (PHB2) are proteins that are ubiquitously expressed, and are present in the nucleus, cytosol, and mitochondria. Depending on the cellular localization, PHB1 and PHB2 have distinctive functions, but more evidence suggests a critical role within mitochondria. In fact, PHB proteins are highly expressed in cells that heavily depend on mitochondrial function. In mitochondria, these two proteins assemble at the inner membrane to form a supra-macromolecular structure, which works as a scaffold for proteins and lipids regulating mitochondrial metabolism, including bioenergetics, biogenesis, and dynamics in order to determine the cell fate, death, or life. PHB alterations have been found in aging and cancer, as well as neurodegenerative, cardiac, and kidney diseases, in which significant mitochondrial impairments have been observed. The molecular mechanisms by which prohibitins regulate mitochondrial function and their role in pathology are reviewed and discussed herein.