Store-operated Ca2+ entry as a key oncogenic Ca2+ signaling driving tumor invasion-metastasis cascade and its translational potential

ATP promotes resident CD34+ cell migration mainly through P2Y2-Stim1-ERK/p38 pathway

Extracellular adenosine triphosphate (ATP) is one of the most abundant biochemical constitutes within the stem cell microenvironment and is postulated to play critical roles in cell migration. However, it is unclear whether ATP regulates the cell migration of CD34+ vascular wall-resident stem/progenitor cells (VW-SCs) and participates in angiogenesis. Therefore, the biological mechanisms of cell migration mediated by ATP was determined by in vivo subcutaneous matrigel plug assay, ex vivo aortic ring assay, in vitro transwell migration assay, and other molecular methods. In the present study, ATP dose-dependently promoted CD34+ VW-SCs migration, which was more obviously attenuated by inhibiting or knocking down P2Y2 than P2Y6. Furthermore, it was confirmed that ATP potently promoted the migration of resident CD34+ cells from cultured aortic artery rings and differentiation into endothelial cells in matrigel plugs by using inducible lineage tracing Cd34-CreERT2; R26-tdTomato mice, whereas P2Y2 and P2Y6 blocker greatly inhibited the effect of ATP. In addition, ATP enhanced the protein expression of stromal interaction molecule 1 (STIM1) on cell membrane, blocking the calcium release-activated calcium (CRAC) channel with shSTIM1 or BTP2 apparently inhibited ATP-evoked intracellular Ca2+ elevation and channel opening, thereby suppressing ATP-driven cell migration. Moreover, extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 and p38 inhibitor SB203580 remarkably inhibited ERK and p38 phosphorylation, cytoskeleton rearrangement, and subsequent cell migration. Unexpectedly, it was found that knocking down STIM1 greatly inhibited ATP-triggered ERK/p38 activation. Taken together, it was suggested that P2Y2 signaled through the CRAC channel mediated Ca2+ influx and ERK/p38 pathway to reorganize the cytoskeleton and promoted the migration of CD34+ VW-SCs.NEW & NOTEWORTHY In this study, we observed that the purinergic receptor P2Y2 is critical in the regulation of vascular wall-resident CD34+ cells' migration. ATP could activate STIM1-mediated extracellular Ca2+ entry by triggering STIM1 translocation to the plasma membrane, and knockdown of STIM1 prevented ERK/p38 activation-mediated cytoskeleton rearrangement and cell migration.

Inhibition of TRPV4 remodels single cell polarity and suppresses the metastasis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor, frequently causing both intrahepatic and extrahepatic metastases. The overall prognosis of patients with metastatic HCC is poor. Recently, single-cell (sc) polarity is proved to be an innate feature of some tumor cells in liquid phase, and directly involved in the cell adhesion to blood vessel and tumor metastasis. Here, we characterize the maintained sc polarity of HCC cells in a suspension culture, and investigate its roles and regulatory mechanisms during metastasis. We demonstrate that transient receptor potential vanilloid 4 (TRPV4) is a promoting regulator of sc polarity via activating Ca²⁺-dependent AMPK/MLC/ERM pathway. This attenuates the adhesion of metastatic HCC cells to vascular endothelial cells. The reduction of cancer metastases can result from TRPV4 inhibition, which not only impacts the migration and invasion of tumor cells, but also prevents the adhesion to vascular endothelial cells. Additionally, we discover a brand-new TRPV4 inhibitor called GL-V9 that modifies the degree of sc polarization and significantly decreases the metastatic capacity of HCC cells. Taken together, our data shows that TRPV4 and calcium signal are significant sc polarity regulators in metastatic HCC, and that the pharmacological intervention that results in HCC cells becoming depolarized suggests a promising treatment for cancer metastasis.

STIM1-regulated exosomal EBV-LMP1 empowers endothelial cells with an aggressive phenotype by activating the Akt/ERK pathway in nasopharyngeal carcinoma

BACKGROUND

Stromal interaction molecule 1 (STIM1)-mediated Ca²⁺ signaling regulates tumor angiogenesis in nasopharyngeal carcinoma (NPC), an Epstein-Barr virus (EBV)-related human malignancy. However, the mechanism by which STIM1 modulates endothelial functional phenotypes contributing to tumor angiogenesis remains elusive.

METHODS

NPC cell-derived exosomes were isolated via differential centrifugation and observed using transmission electron microscopy. Exosome particle sizes were assessed by nanoparticle tracking analysis (NTA). Uptake of exosomes by recipient ECs was detected by fluorescent labeling of the exosomes with PKH26. Tumor angiogenesis-associated profiles were characterized by determining cell proliferation, migration, tubulogenesis and permeability in human umbilical vein endothelial cells (HUVECs). Activation of the Akt/ERK pathway was assessed by detecting the phosphorylation levels using Western blotting. A chick embryo chorioallantoic membrane (CAM) xenograft model was employed to study tumor-associated neovascularization in vivo.

RESULTS

We found that NPC cell-derived exosomes harboring EBV-encoded latent membrane protein 1 (LMP1) promoted proliferation, migration, tubulogenesis and permeability by activating the Akt/ERK pathway in ECs. STIM1 silencing reduced LMP1 enrichment in NPC cell-derived exosomes, thereby reversing its pro-oncogenic effects in an Akt/ERK pathway-dependent manner. Furthermore, STIM1 knockdown in NPC cells blunted tumor-induced vascular network formation and inhibited intra-tumor neovascularization in the chorioallantoic membrane (CAM) xenograft model.

CONCLUSION

STIM1 regulates tumor angiogenesis by controlling exosomal EBV-LMP1 delivery to ECs in the NPC tumor microenvironment. Blocking exosome-mediated cell-to-cell horizontal transfer of EBV-associated oncogenic signaling molecules may be an effective therapeutic strategy for NPC.

CircRNA_0017076 acts as a sponge for miR-185-5p in the control of epithelial-to-mesenchymal transition of tubular epithelial cells during renal interstitial fibrosis

Renal interstitial fibrosis (RIF) is a common pathological hallmark of progressive chronic kidney disease (CKD). Circular RNAs (circRNAs) are involved in certain renal diseases, but their role in RIF is largely unknown. The present study investigated the effects and potential mechanisms of circRNA_0017076 in RIF. CircRNA_0017076 expression was markedly upregulated in transforming growth factor-β1 (TGF-β1)-treated renal tubular epithelial cells (RTECs) and kidney biopsy samples from patients with RIF. Functional assays showed that circRNA_0017076 colocalized with microRNA-185-5p (miR-185-5p) and inhibited miR-185-5p function via direct binding to miR-185-5p. In vitro, the knockdown of circRNA_0017076 inhibited the calcium ion (Ca²⁺) influx-mediated epithelial-to-mesenchymal transition (EMT) of RTECs and downregulated the expression of stromal interaction molecule 1 (STIM1), which is a target protein of miR-185-5p. Silencing mmu_circ_0004488 reduced fibrotic lesions in the kidneys of unilateral ureteral obstruction (UUO) mice by targeting the miR-185-5p/Stim1 axis. For the first time, we identified circRNA_0017076 as a sponge for miR-185-5p, which regulates STIM1 gene expression and is involved in RIF. Our results support circRNA_0017076 as a potential therapeutic target for RIF disease.

Stromal Interaction Molecule 1 (STIM1) is a Potential Prognostic Biomarker and Correlates with Immune Infiltrates in Solid Tumors

Increasing evidence has shown that stromal interaction molecule 1 (STIM1), a key subunit of store-operated Ca2+ entry (SOCE), is closely associated with tumor growth, development, and metastasis. However, there is no report of a comprehensive assessment of STIM1 in pan-cancer. This study aimed to perform a general analysis of STIM1 in human tumors, including its molecular characteristics, functional mechanisms, clinical significance, and immune infiltrates correlation based on pan-cancer data from The Cancer Genome Atlas (TCGA). Gene expression analysis was investigated using TCGA RNA-seq data, the Tumor Immune Estimation Resource (TIMER). Phosphorylation analysis was undertaken using the Clinical Proteomic Tumor Analysis Consortium (CP-TAC) and the PhosphoNET database. Genetic alterations of STIM1 were analyzed using cBioPortal. Prognostic analysis was via the R package "survival" function and the Kaplan-Meier plotter. Functional enrichment analysis was via by the R package "cluster Profiler" function. The association between STIM1 and tumor-infiltrating immune cells and immune markers was by the R package "GSVA" function and TIMER. STIM1 was differentially expressed and associated with distinct clinical stages in multiple tumors. The phosphorylation of STIM1 at S673 is highly expressed in clear cell renal carcinoma and lung adenocarcinoma tumors compared to normal tissues. STIM1 genetic alterations correlate with poor prognosis in several tumors, including ovarian cancer and lung squamous cell carcinomas. High STIM1 expression is associated with good or poor prognosis across diverse tumors. Overall survival (OS) analysis indicated that STIM1 is a favorable prognostic factor for patients with BRCA, KIRC, LIHC, LUAD, OV, SARC, and UCEC, and is a risk prognostic factor for BLCA, KIRP, STAD, and UVM. There is a close correlation between STIM1 expression and immune cell infiltration, immune-regulated genes, chemokines, and immune checkpoints in a variety of tumors. STIM1 functions differently in diverse tumors, playing an oncogenic or antitumor role. Moreover, It may serve as a prognostic biomarker and an immunotherapy target across multiple tumors.

Down the membrane hole: Ion channels in protozoan parasites

Parasitic diseases caused by protozoans are highly prevalent around the world, disproportionally affecting developing countries, where coinfection with other microorganisms is common. Control and treatment of parasitic infections are constrained by the lack of specific and effective drugs, plus the rapid emergence of resistance. Ion channels are main drug targets for numerous diseases, but their potential against protozoan parasites is still untapped. Ion channels are membrane proteins expressed in all types of cells, allowing for the flow of ions between compartments, and regulating cellular functions such as membrane potential, excitability, volume, signaling, and death. Channels and transporters reside at the interface between parasites and their hosts, controlling nutrient uptake, viability, replication, and infectivity. To understand how ion channels control protozoan parasites fate and to evaluate their suitability for therapeutics, we must deepen our knowledge of their structure, function, and modulation. However, methodological approaches commonly used in mammalian cells have proven difficult to apply in protozoans. This review focuses on ion channels described in protozoan parasites of clinical relevance, mainly apicomplexans and trypanosomatids, highlighting proteins for which molecular and functional evidence has been correlated with their physiological functions.

Science CommuniCa2+tion Developing Scientific Literacy on Calcium: The Involvement of CRAC Currents in Human Health and Disease

All human life starts with a calcium (Ca2+) wave. This ion regulates a plethora of cellular functions ranging from fertilisation and birth to development and cell death. A sophisticated system is responsible for maintaining the essential, tight concentration of calcium within cells. Intricate components of this Ca2+ network are store-operated calcium channels in the cells' membrane. The best-characterised store-operated channel is the Ca2+ release-activated Ca2+ (CRAC) channel. Currents through CRAC channels are critically dependent on the correct function of two proteins: STIM1 and Orai1. A disruption of the precise mechanism of Ca2+ entry through CRAC channels can lead to defects and in turn to severe impacts on our health. Mutations in either STIM1 or Orai1 proteins can have consequences on our immune cells, the cardiac and nervous system, the hormonal balance, muscle function, and many more. There is solid evidence that altered Ca2+ signalling through CRAC channels is involved in the hallmarks of cancer development: uncontrolled cell growth, resistance to cell death, migration, invasion, and metastasis. In this work we highlight the importance of Ca2+ and its role in human health and disease with focus on CRAC channels.

The Important Role of Ion Transport System in Cervical Cancer

Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca²⁺ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl⁻ channels and K⁺-Cl⁻ cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca²⁺ homeostasis, the Ca²⁺ store sensor STIM molecules and plasma membrane Ca²⁺ channel Orai proteins, the predominant Ca²⁺ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.

Orai3 Regulates Pancreatic Cancer Metastasis by Encoding a Functional Store Operated Calcium Entry Channel

Store operated Ca²⁺ entry (SOCE) mediated by Orai1/2/3 channels is a highly regulated and ubiquitous Ca²⁺ influx pathway. Although the role of Orai1 channels is well studied, the significance of Orai2/3 channels is still emerging in nature. In this study, we performed extensive bioinformatic analysis of publicly available datasets and observed that Orai3 expression is inversely associated with the mean survival time of PC patients. Orai3 expression analysis in a battery of PC cell lines corroborated its differential expression profile. We then carried out thorough Ca²⁺ imaging experiments in six PC cell lines and found that Orai3 forms a functional SOCE channel in PC cells. Our in vitro functional assays show that Orai3 regulates PC cell cycle progression, apoptosis and migration. Most importantly, our in vivo xenograft studies demonstrate a critical role of Orai3 in PC tumor growth and secondary metastasis. Mechanistically, Orai3 controls G₁ phase progression, matrix metalloproteinase expression and epithelial-mesenchymal transition in PC cells. Taken together, this study for the first-time reports that Orai3 drives aggressive phenotypes of PC cells, i.e., migration in vitro and metastasis in vivo. Considering that Orai3 overexpression leads to poor prognosis in PC patients, it appears to be a highly attractive therapeutic target.