Calreticulin regulates vascular endothelial growth factor-A mRNA stability in gastric cancer cells

RNA binding proteins (RBPs) on genetic stability and diseases

RNA-binding proteins (RBPs) are integral components of cellular machinery, playing crucial roles in the regulation of gene expression and maintaining genetic stability. Their interactions with RNA molecules govern critical processes such as mRNA splicing, stability, localization, and translation, which are essential for proper cellular function. These proteins interact with RNA molecules and other proteins to form ribonucleoprotein complexes (RNPs), hence controlling the fate of target RNAs. The interaction occurs via RNA recognition motif, the zinc finger domain, the KH domain and the double stranded RNA binding motif (all known as RNA-binding domains (RBDs). These domains are found within the coding sequences (intron and exon domains), 5' untranslated regions (5'UTR) and 3' untranslated regions (3'UTR). Dysregulation of RBPs can lead to genomic instability, contributing to various pathologies, including cancer neurodegenerative diseases, and metabolic disorders. This study comprehensively explores the multifaceted roles of RBPs in genetic stability, highlighting their involvement in maintaining genomic integrity through modulation of RNA processing and their implications in cellular signalling pathways. Furthermore, it discusses how aberrant RBP function can precipitate genetic instability and disease progression, emphasizing the therapeutic potential of targeting RBPs in restoring cellular homeostasis. Through an analysis of current literature, this study aims to delineate the critical role of RBPs in ensuring genetic stability and their promise as targets for innovative therapeutic strategies.

Pinacidil ameliorates cardiac microvascular ischemia-reperfusion injury by inhibiting chaperone-mediated autophagy of calreticulin

Calcium overload is the key trigger in cardiac microvascular ischemia-reperfusion (I/R) injury, and calreticulin (CRT) is a calcium buffering protein located in the endoplasmic reticulum (ER). Additionally, the role of pinacidil, an antihypertensive drug, in protecting cardiac microcirculation against I/R injury has not been investigated. Hence, this study aimed to explore the benefits of pinacidil on cardiac microvascular I/R injury with a focus on endothelial calcium homeostasis and CRT signaling. Cardiac vascular perfusion and no-reflow area were assessed using FITC-lectin perfusion assay and Thioflavin-S staining. Endothelial calcium homeostasis, CRT-IP3Rs-MCU signaling expression, and apoptosis were assessed by real-time calcium signal reporter GCaMP8, western blotting, and fluorescence staining. Drug affinity-responsive target stability (DARTS) assay was adopted to detect proteins that directly bind to pinacidil. The present study found pinacidil treatment improved capillary density and perfusion, reduced no-reflow and infraction areas, and improved cardiac function and hemodynamics after I/R injury. These benefits were attributed to the ability of pinacidil to alleviate calcium overload and mitochondria-dependent apoptosis in cardiac microvascular endothelial cells (CMECs). Moreover, the DARTS assay showed that pinacidil directly binds to HSP90, through which it inhibits chaperone-mediated autophagy (CMA) degradation of CRT. CRT overexpression inhibited IP3Rs and MCU expression, reduced mitochondrial calcium inflow and mitochondrial injury, and suppressed endothelial apoptosis. Importantly, endothelial-specific overexpression of CRT shared similar benefits with pinacidil on cardiovascular protection against I/R injury. In conclusion, our data indicate that pinacidil attenuated microvascular I/R injury potentially through improving CRT degradation and endothelial calcium overload.

Circ_0001946 Promotes the Development of Acute Myeloid Leukemia by Upregulating PDL1

Objective

Circ_0001946 has been identified as an oncogenic factor, and the aim of this study was to explore the detailed roles and putative targets of circ_0001946 in acute myeloid leukemia (AML).

Materials and Methods

Levels of circ_0001946 were examined in AML tissues and cells. Furthermore, the regulatory functions of circ_0001946 in AML were explored. The expression of circ_0001946 was evaluated in AML samples and a matched para-carcinoma control, as well as in AML cell lines and a human bone marrow stromal cell line using reverse transcription-quantitative polymerase chain reaction. Cell proliferation was examined using a CCK-8 kit, and migration/invasion was measured by transwell assay. Furthermore, interactions between associated molecules were assessed using RNA pulldown, and the mRNA stability of the relevant gene was examined by mRNA stability assay.

Results

Our data indicated that circ_0001946 was upregulated in AML specimens/cells. Additionally, overexpression of circ_0001946 promoted the proliferation, migration, and invasion of AML cells and, vice versa, these biological processes were suppressed by knockdown of circ_0001946. Furthermore, PDL1 is a potential downstream molecule of circ_0001946 in AML and its stability was improved by circ_0001946. The expression of PDL1 was increased in AML specimens and positively correlated with circ_0001946 expression. Moreover, biological behavioral alterations in AML cells induced by oe-circ_0001946 were abrogated by sh-PDL1 and the effects of sh-circ_0001946 were enhanced by treatment with sh-PDL1.

Conclusion

Taken together, these data suggest that levels of circ_0001946 are elevated in AML and that circ_0001946 could promote the growth of AML cells. Furthermore, PDL1 is a novel downstream molecule of circ_0001946 in AML. Circ_0001946/PDL1 signaling may play crucial roles in tumor progression in AML and could be a novel candidate for targeted treatments for AML patients.

Calreticulin enhances gastric cancer metastasis by dimethylating H3K9 in the E-cadherin promoter region mediating by G9a

The latest study shows that gastric cancer (GC) ranked the fifth most common cancer (5.6%) with over 1 million estimated new cases annually and the fourth most common cause of cancer death (7.7%) globally in 2020. Metastasis is the leading cause of GC treatment failure. Therefore, clarifying the regulatory mechanisms for GC metastatic process is necessary. In the current study, we discovered that calreticulin (CALR) was highly expressed in GC tissues and related to lymph node metastasis and patient’s terrible prognosis. The introduction of CALR dramatically promoted GC cell migration in vitro and in vivo, while the repression of CALR got the opposite effects. Cell migration is a functional consequence of the epithelial-mesenchymal transition (EMT) and is related to adhesion of cells. Additionally, we observed that CALR inhibition or overexpression regulated the expression of EMT markers (E-cadherin, ZO-1, Snail, N-cadherin, and ZEB1) and cellular adhesive moleculars (Fibronectin, integrin β1and MMP2). Mechanistically, our data indicated that CALR could mediate DNA methylation of E-cadherin promoter by interacting with G9a, a major euchromatin methyltransferase responsible for methylation of histone H3 on lysine 9(H3K9me2) and recruiting G9a to the E-cadherin promoter. Knockdown of G9a in CALR overexpressing models restored E-cadherin expression and blocked the stimulatory effects of CALR on GC cell migration. Taken together, these findings not only reveal critical roles of CALR medicated GC metastasis but also provide novel treatment strategies for GC.

Calreticulin (CALR)-induced activation of NF-ĸB signaling pathway boosts lung cancer cell proliferation

Calreticulin (CALR) is known to be aberrantly expressed in lung though the etiology underlying this phenomenon remains undetermined. The (Cancer Genome Atlas) databases were adopted to evaluate the expression status of CALR in pan-cancer, including Lung adenocarcinoma (LUAD) and Lung squamous cell carcinoma (LUSC) accompanied with Genotype-Tissue Expression project (GETx) database. Receiver operating characteristic (ROC) curves and Kaplan-Meier survival curve were plotted to assess its clinical significance in lung cancer. CCK8 and colony formation assays were conducted in addition to in vivo assays. The impact of CALR expression on NF-ĸB-mediated luciferase activity was detected by Luciferase assays. The regulatory relationship between CALR and NF-ĸB was further verified by NF-ĸB inhibitor treatment. LUAD and LUSC tissues reflected marked elevation in the mRNA levels of CALR. ROC analysis showed that CALR expression had a diagnostic value for LUAD or LUSC patients. High-CARL patients demonstrated inferior survival compared to that of Low-CALR patients. Functional assays revealed increased proliferative behaviors of A549 and H1299 cells associated with highly amplified while CALR gene inactivation could reduce the proliferation of both cells. CALR depletion decreased xenograft tumor growth. NF-ĸB transcriptional activity was found to be stimulated with CALR overexpression and reduced in CALR-deficient lung cancer cells, thereby clearly indicating CALR-dependent NF-ĸB activation. NF-ĸB specific inhibitors further validated enhanced NF-ĸB activity mediated by CALR overexpression. Conclusively, our results the role of CALR in lung cancer cells, indicating that highly expressed CALR proliferation at least by activation of NF-ĸB signaling pathway.

Advances in Intracellular Calcium Signaling Reveal Untapped Targets for Cancer Therapy

Intracellular Ca2+ distribution is a tightly regulated process. Numerous Ca2+ chelating, storage, and transport mechanisms are required to maintain normal cellular physiology. Ca2+-binding proteins, mainly calmodulin and calbindins, sequester free intracellular Ca2+ ions and apportion or transport them to signaling hubs needing the cations. Ca2+ channels, ATP-driven pumps, and exchangers assist the binding proteins in transferring the ions to and from appropriate cellular compartments. Some, such as the endoplasmic reticulum, mitochondria, and lysosomes, act as Ca2+ repositories. Cellular Ca2+ homeostasis is inefficient without the active contribution of these organelles. Moreover, certain key cellular processes also rely on inter-organellar Ca2+ signaling. This review attempts to encapsulate the structure, function, and regulation of major intracellular Ca2+ buffers, sensors, channels, and signaling molecules before highlighting how cancer cells manipulate them to survive and thrive. The spotlight is then shifted to the slow pace of translating such research findings into anticancer therapeutics. We use the PubMed database to highlight current clinical studies that target intracellular Ca2+ signaling. Drug repurposing and improving the delivery of small molecule therapeutics are further discussed as promising strategies for speeding therapeutic development in this area.

Calreticulin increases growth and progression of natural killer/T-cell lymphoma

In this study, we investigated the role of calreticulin (CALR) in the pathogenesis of natural killer/T-cell lymphoma (NKTCL). CALR expression was significantly higher in the NKTCL tissues than normal control tissues in the GSE80632 dataset. High CALR expression correlated with poorer overall survival of NKTCL patients (P = 0.0248). CALR mRNA and protein levels were significantly higher in NKTCL cell lines (NK92, SNK6, and SNT8) than normal NK cells. CALR-silenced SNK6 cells generated significantly smaller xenograft tumors in immunodeficient NCG mice than control SNK6 cells. CALR-knockdown NKTCL cells showed significantly less in vitro proliferation and Transwell migration than the controls. CALR knockdown inhibited G1-to-S phase cell cycle progression by increasing the levels of p27 cell cycle inhibitor and reducing the levels of cyclin E2 and cyclin-dependent kinase 2 (CDK2). CALR knockdown inhibited epithelial-to-mesenchymal transition (EMT) by decreasing the levels of β-catenin and TCF/ZEB1 and upregulating E-cadherin. These data demonstrate that CALR regulates the growth and progression of NKTCL cells by modulating G1-to-S cell cycle progression and EMT.