Unraveling the structures, functions and mechanisms of epithelial membrane protein family in human cancers

Neural stem cell relay from B1 to B2 cells in the adult mouse ventricular-subventricular zone

Neurogenesis and gliogenesis continue in the ventricular-subventricular zone (V-SVZ) of the adult rodent brain. V-SVZ astroglial cells with apical contact with the ventricle (B1 cells) function as neural stem cells (NSCs). B1 cells sharply decline during early postnatal life; in contrast, neurogenesis decreases at a slower rate. Here, we show that a second population of astroglia (B2 cells) that do not contact the ventricle also function as NSCs in the adult mouse brain. B2 cell numbers increase postnatally, are sustained in adults, and decrease with aging. We reveal the transcriptomic profile of B1 and B2 cells and show that, like B1 cells, B2 cells can be quiescent or activated. Transplantation and lineage tracing of B2 cells demonstrate their function as primary progenitors for adult neurogenesis. This study reveals that NSC function is progressively relayed from B1 to B2 progenitors helping explain how neurogenesis is maintained into adult life.

Tumor cell-derived EMP1 is essential for cancer-associated fibroblast infiltration in tumor microenvironment of triple-negative breast cancer

The role of epithelial membrane protein 1 (EMP1) in tumor microenvironment (TME) remodeling has not yet been elucidated. In addition, the biological function of EMP1 in triple-negative breast cancer (TNBC) is largely unclear. In this study, we examined the infiltration landscape of cell types in the TME of breast cancer, and found that EMP1 expression was positively correlated with stromal and microenvironmental scores. Infiltration analysis and immunohistochemical (IHC) staining of serial sections confirmed the critical role of EMP1 in cancer-associated fibroblast (CAF) infiltration. Cell co-culture assays, xenograft tumor experiments, loss-of-function, gain-of-function, RNA sequencing studies, and rescue assays were performed to confirm the role of EMP1 in CAF infiltration in vitro and in vivo. These findings revealed that EMP1 depletion in TNBC cells resulted in considerable inhibition of CAF infiltration in vivo and in vitro. Mechanistically, EMP1 knockdown induced a substantial decrease in IL6 secretion from TNBC through the NF-κB signaling pathway, hindering CAF proliferation and subsequently inhibiting TNBC progression and metastasis. These cumulative results indicate that EMP1 functions as an oncogene in TNBC by mediating the cell communication of TNBC and CAFs. Targeted inhibition of EMP1 by suppressing CAF infiltration is a promising strategy for TNBC treatment.

Targeting enolase 1 reverses bortezomib resistance in multiple myeloma through YWHAZ/Parkin axis

BACKGROUND

Enolase 1 (ENO1) is a conserved glycolytic enzyme that regulates glycolysis metabolism. However, its role beyond glycolysis in the pathophysiology of multiple myeloma (MM) remains largely elusive. Herein, this study aimed to elucidate the function of ENO1 in MM, particularly its impact on mitophagy under bortezomib-induced apoptosis.

METHODS

The bone marrow of clinical MM patients and healthy normal donors was used to compare the expression level of ENO1. Using online databases, we conducted an analysis to examine the correlation between ENO1 expression and both clinicopathological characteristics and patient outcomes. To investigate the biological functions of ENO1 in MM and the underlying molecular mechanisms involved, we conducted the following experiment: construction of a subcutaneous graft tumor model, co-immunoprecipitation, western blot, quantitative real-time polymerase chain reaction, immunohistochemistry, flow cytometry, and cell functional assays.

RESULTS

ENO1 was identified as an unfavorable prognostic factor in MM. ENO1 knockdown suppresses tumorigenicity and causes cell cycle arrest. Inhibition of ENO1-regulated mitophagy sensitizes tumor cells to apoptosis. ENO1 enhanced the stability of the YWHAZ protein by increasing the acetylation of lysine in YWHAZ while antagonizing its ubiquitination, which in turn promoted mitophagy. HDAC6 mediates the deacetylation of YWHAZ by deacetylating the K138 site of YWHAZ. Inhibition of HDAC6 increased YWHAZ acetylation and decreased YWHAZ ubiquitination. Furthermore, combination treatment with bortezomib and pharmaceutical agents targeting ENO1 has synergistic anti-MM effects both in vivo and in vitro.

CONCLUSION

Our data suggest that ENO1 promotes MM tumorigenesis and progression. ENO1 activates mitophagy by promoting the stability of YWHAZ and inhibits apoptosis and thus, leads to the drug resistance. ENO1-dependent mitophagy promotes MM proliferation and suppresses the level of bortezomib-induced apoptosis. Inhibition of ENO1 may represent a potential strategy to reverse the resistance of MM to bortezomib.

Acute myeloid leukemia stem cell signature gene EMP1 is not an eligible therapeutic target

BACKGROUND

Relapse in pediatric acute myeloid leukemia (pedAML) patients is known to be associated with residual leukemic stem cells (LSC). We have previously shown that epithelial membrane protein 1 (EMP1) is significantly overexpressed in LSC compared to hematological stem cell fractions. EMP1 was also documented as part of the 17-gene stemness score and a 6-membrane protein gene score, both correlating high EMP1 expression with worse overall survival. However, its potential as a therapeutic target in pedAML is still unexplored.

METHODS

Association analyses of EMP1 expression with clinical and molecular AML characteristics were performed. Expression of EMP1 was evaluated in pedAML and cord blood samples. Expression in normal blood cells and tissues was evaluated by flow cytometry and immunohistochemistry, respectively.

RESULTS

In silico analyses showed variable mRNA expression of EMP1 in multiple pedAML datasets, and a significant correlation between high EMP1 transcript levels and the presence of inv(16). Flow cytometry showed overexpression of EMP1 in pedAML samples, as well as expression in normal blood subsets. Importantly, immunohistochemistry revealed EMP1 expression in multiple normal tissues.

CONCLUSION

Although EMP1 presents as an interesting membrane-associated target in pedAML, its abundant expression in normal blood cells and tissues will impede it from further exploration as a therapeutic target.

IMPACT

EMP1 is highly expressed in multiple cancer types, but expression in acute myeloid leukemia (AML) and normal tissues is unexplored. As EMP1 is investigated in other cancer types, expression in normal tissues and blood cells is relevant in predicting the success of EMP1-targeted therapies. In this study, we showed expression of EMP1 in multiple tissues, predicting high on-target off-tumor toxicity, which will warn other researchers of possible toxicities when generating EMP1-targeted therapy. Finally, we showed that high EMP1 expression is associated with better overall survival of pediatric AML patients, reducing the need for EMP1-targeted therapy.

The Multifaceted Role of Epithelial Membrane Protein 2 in Cancer: from Biomarker to Therapeutic Target

Tetraspanin superfamily proteins not only facilitate the trafficking of specific proteins to distinct plasma membrane domains but also influence cell-to-cell and cell-extracellular matrix interactions. Among these proteins, Epithelial Membrane Protein 2 (EMP2), a member of the growth arrest-specific gene 3/peripheral myelin protein 22 (GAS3/PMP22) family, is known to affect key cellular processes. Recent studies have revealed that EMP2 modulates critical signaling pathways and interacts with adhesion molecules and growth factor receptors, underscoring its potential as a biomarker for cancer diagnosis and prognosis. These findings suggest that EMP2 expression patterns could provide valuable insights into tumorigenesis and metastasis. Moreover, EMP2 has emerged as a promising therapeutic target, with approaches aimed at inhibiting or modulating its activity showing potential to disrupt tumor growth and metastasis. This review provides a comprehensive overview of recent advances in understanding the multifaceted roles of EMP2 in cancer, with a focus on its underlying mechanisms and clinical significance.

Neural Stem Cell Relay from B1 to B2 cells in the adult mouse Ventricular-Subventricular Zone

Neurogenesis and gliogenesis continue in the Ventricular-Subventricular Zone (V-SVZ) of the adult rodent brain. B1 cells are astroglial cells derived from radial glia that function as primary progenitors or neural stem cells (NSCs) in the V-SVZ. B1 cells, which have a small apical contact with the ventricle, decline in numbers during early postnatal life, yet neurogenesis continues into adulthood. Here we found that a second population of V-SVZ astroglial cells (B2 cells), that do not contact the ventricle, function as NSCs in the adult brain. B2 cell numbers increase postnatally, remain constant in 12-month-old mice and decrease by 18 months. Transcriptomic analysis of ventricular-contacting and non-contacting B cells revealed key molecular differences to distinguish B1 from B2 cells. Transplantation and lineage tracing of B2 cells demonstrate their function as primary progenitors for adult neurogenesis. This study reveals how NSC function is relayed from B1 to B2 progenitors to maintain adult neurogenesis.

MicroRNAs in the Pathogenesis of Preeclampsia-A Case-Control In Silico Analysis

Preeclampsia (PE) occurs in 5% to 7% of all pregnancies, and the PE that results from abnormal placentation acts as a primary cause of maternal and neonatal morbidity and mortality. The objective of this secondary analysis was to elucidate the pathogenesis of PE by probing protein-protein interactions from in silico analysis of transcriptomes between PE and normal placenta from Gene Expression Omnibus (GSE149812). The pathogenesis of PE is apparently determined by associations of miRNA molecules and their target genes and the degree of changes in their expressions with irregularities in the functions of hemostasis, vascular systems, and inflammatory processes at the fetal-maternal interface. These irregularities ultimately lead to impaired placental growth and hypoxic injuries, generally manifesting as placental insufficiency. These differentially expressed miRNAs or genes in placental tissue and/or in blood can serve as novel diagnostic and therapeutic biomarkers.

Focal adhesion kinase: from biological functions to therapeutic strategies

Focal adhesion kinase (FAK), a nonreceptor cytoplasmic tyrosine kinase, is a vital participant in primary cellular functions, such as proliferation, survival, migration, and invasion. In addition, FAK regulates cancer stem cell activities and contributes to the formation of the tumor microenvironment (TME). Importantly, increased FAK expression and activity are strongly associated with unfavorable clinical outcomes and metastatic characteristics in numerous tumors. In vitro and in vivo studies have demonstrated that modulating FAK activity by application of FAK inhibitors alone or in combination treatment regimens could be effective for cancer therapy. Based on these findings, several agents targeting FAK have been exploited in diverse preclinical tumor models. This article briefly describes the structure and function of FAK, as well as research progress on FAK inhibitors in combination therapies. We also discuss the challenges and future directions regarding anti-FAK combination therapies.