Differential expression of store-operated calcium- and proliferation-related genes in hepatocellular carcinoma cells following TRPC1 ion channel silencing

Targeting Dysregulated Ion Channels in Liver Tumors with Venom Peptides

The regulation of cellular processes by ion channels has become central to the study of cancer mechanisms. Designing molecules that can modify ion channels specific to tumor cells is a promising area of targeted drug delivery and therapy. Despite their potential in drug discovery, venom peptides-a group of natural products-have largely remained understudied and under-characterized. In general, venom peptides display high specificity and selectivity for their target ion channels. Therefore, they may represent an effective strategy for selectively targeting the dysregulation of ion channels in tumor cells. This review examines existing venom peptide therapies for different cancer types and focuses on the application of snail venom peptides in hepatocellular carcinoma (HCC), the most common form of primary liver cancer worldwide. We provide insights into the mode of action of venom peptides that have been shown to target tumors. We also explore the benefit of using new computational methods like de novo protein structure prediction to screen venom peptides and identify potential druggable candidates. Finally, we summarize the role of cell culture, animal, and organoid models in developing effective therapies against HCC and highlight the need for creating models that represent the most disproportionately affected ethnicities in HCC.

Role of TRP Channels in Liver-Related Diseases

The liver plays a crucial role in preserving the homeostasis of an entire organism by metabolizing both endogenous and exogenous substances, a process that relies on the harmonious interactions of hepatocytes, hepatic stellate cells (HSCs), Kupffer cells (KCs), and vascular endothelial cells (ECs). The disruption of the liver's normal structure and function by diverse pathogenic factors imposes a significant healthcare burden. At present, most of the treatments for liver disease are palliative in nature, rather than curative or restorative. Transient receptor potential (TRP) channels, which are extensively expressed in the liver, play a crucial role in regulating intracellular cation concentration and serve as the origin or intermediary stage of certain signaling pathways that contribute to liver diseases. This review provides an overview of recent developments in liver disease research, as well as an examination of the expression and function of TRP channels in various liver cell types. Furthermore, we elucidate the molecular mechanism by which TRP channels mediate liver injury, liver fibrosis, and hepatocellular carcinoma (HCC). Ultimately, the present discourse delves into the current state of research and extant issues pertaining to the targeting of TRP channels in the treatment of liver diseases and other ailments. Despite the numerous obstacles encountered, TRP channels persist as an extremely important target for forthcoming clinical interventions aimed at treating liver diseases.

Function of TRPC1 in modulating hepatocellular carcinoma progression

The liver is the main organ of metabolism in the human body, and it is easy to suffer from hepatitis, cirrhosis, liver cancer, and other diseases, the most serious of which is liver cancer. Worldwide, liver cancer is the most common and deadly malignant tumor, the third leading cause of cancer death in the world. Based on TCGA and ICGC databases, our research discovered the important role of TRPC1 in liver cancer through bioinformatics. The results showed that TRPC1 was over-expressed in hepatocellular carcinoma, and the higher the expression level of TRPC1, the worse the OS and the lower the survival rate. TRPC1 was a risk factor affecting the overall survival probability of hepatocellular carcinoma patients. By analyzing the function of the TRP family in liver cancer, TRPC1 might promote the occurrence of liver cancer by up-regulating common signal pathways in tumors such as tumor proliferation signature, and down-regulating important metabolic reactions such as retinol metabolism. In addition, TRPC1 could promote the development of liver cancer by up-regulating the expression of ABI2, MAPRE1, YEATS2, MTA3, TMEM237, MTMR2, CCDC6, AC069544.2, and NCBP2 genes. These results illustrate that TRPC1 is very valuable in the study of liver cancer.

Expression and functions of transient receptor potential channels in liver diseases

Liver diseases constitute a major healthcare burden globally, including acute hepatic injury resulted from acetaminophen overdose, ischemia-reperfusion or hepatotropic viral infection and chronic hepatitis, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC). Attainable treatment strategies for most liver diseases remain inadequate, highlighting the importance of substantial pathogenesis. The transient receptor potential (TRP) channels represent a versatile signalling mechanism regulating fundamental physiological processes in the liver. It is not surprising that liver diseases become a newly explored field to enrich our knowledge of TRP channels. Here, we discuss recent findings revealing TRP functions across the fundamental pathological course from early hepatocellular injury caused by various insults, to inflammation, subsequent fibrosis and hepatoma. We also explore expression levels of TRPs in liver tissues of ALD, NAFLD and HCC patients from Gene Expression Omnibus (GEO) or The Cancer Genome Atlas (TCGA) database and survival analysis estimated by Kaplan-Meier Plotter. At last, we address the therapeutical potential and challenges by pharmacologically targeting TRPs to treat liver diseases. The aim is to provide a better understanding of the implications of TRP channels in liver diseases, contributing to the discovery of novel therapeutic targets and efficient drugs.

Acid Adaptation Promotes TRPC1 Plasma Membrane Localization Leading to Pancreatic Ductal Adenocarcinoma Cell Proliferation and Migration through Ca2+ Entry and Interaction with PI3K/CaM

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers globally, with a 5-year overall survival of less than 10%. The development and progression of PDAC are linked to its fluctuating acidic tumor microenvironment. Ion channels act as important sensors of this acidic tumor microenvironment. They transduce extracellular signals and regulate signaling pathways involved in all hallmarks of cancer. In this study, we evaluated the interplay between a pH-sensitive ion channel, the calcium (Ca²⁺) channel transient receptor potential C1 (TRPC1), and three different stages of the tumor microenvironment, normal pH, acid adaptation, and acid recovery, and its impact on PDAC cell migration, proliferation, and cell cycle progression. In acid adaptation and recovery conditions, TRPC1 localizes to the plasma membrane, where it interacts with PI3K and calmodulin, and permits Ca²⁺ entry, which results in downstream signaling, leading to proliferation and migration. Thus, TRPC1 exerts a more aggressive role after adaptation to the acidic tumor microenvironment.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, with a low overall survival rate of less than 10% and limited therapeutic options. Fluctuations in tumor microenvironment pH are a hallmark of PDAC development and progression. Many ion channels are bona fide cellular sensors of changes in pH. Yet, the interplay between the acidic tumor microenvironment and ion channel regulation in PDAC is poorly understood. In this study, we show that acid adaption increases PANC-1 cell migration but attenuates proliferation and spheroid growth, which are restored upon recovery. Moreover, acid adaptation and recovery conditions favor the plasma membrane localization of the pH-sensitive calcium (Ca²⁺) channel transient receptor potential C1 (TRPC1), TRPC1-mediated Ca²⁺ influx, channel interaction with the PI3K p85α subunit and calmodulin (CaM), and AKT and ERK1/2 activation. Knockdown (KD) of TRPC1 suppresses cell migration, proliferation, and spheroid growth, notably in acid-recovered cells. KD of TRPC1 causes the accumulation of cells in G0/G1 and G2/M phases, along with reduced expression of CDK6, −2, and −1, and cyclin A, and increased expression of p21^CIP1. TRPC1 silencing decreases the basal Ca²⁺ influx in acid-adapted and -recovered cells, but not in normal pH conditions, and Ca²⁺ chelation reduces cell migration and proliferation solely in acid adaptation and recovery conditions. In conclusion, acid adaptation and recovery reinforce the involvement of TRPC1 in migration, proliferation, and cell cycle progression by permitting Ca²⁺ entry and forming a complex with the PI3K p85α subunit and CaM.

The TRPC1 Channel Forms a PI3K/CaM Complex and Regulates Pancreatic Ductal Adenocarcinoma Cell Proliferation in a Ca2+-Independent Manner

Dysregulation of the transient receptor canonical ion channel (TRPC1) has been found in several cancer types, yet the underlying molecular mechanisms through which TRPC1 impacts pancreatic ductal adenocarcinoma (PDAC) cell proliferation are incompletely understood. Here, we found that TRPC1 is upregulated in human PDAC tissue compared to adjacent pancreatic tissue and this higher expression correlates with low overall survival. TRPC1 is, as well, upregulated in the aggressive PDAC cell line PANC-1, compared to a duct-like cell line, and its knockdown (KD) reduced cell proliferation along with PANC-1 3D spheroid growth by arresting cells in the G1/S phase whilst decreasing cyclin A, CDK2, CDK6, and increasing p21^CIP1 expression. In addition, the KD of TRPC1 neither affected Ca²⁺ influx nor store-operated Ca²⁺ entry (SOCE) and reduced cell proliferation independently of extracellular calcium. Interestingly, TRPC1 interacted with the PI3K-p85α subunit and calmodulin (CaM); both the CaM protein level and AKT phosphorylation were reduced upon TRPC1 KD. In conclusion, our results show that TRPC1 regulates PDAC cell proliferation and cell cycle progression by interacting with PI3K-p85α and CaM through a Ca²⁺-independent pathway.

Tanreqing Injection Regulates Cell Function of Hypoxia-Induced Human Pulmonary Artery Smooth Muscle Cells (HPASMCs) through TRPC1/CX3CL1 Signaling Pathway

Hypoxia-induced pulmonary arterial hypertension (HPAH) is due to hypoxia caused by vascular endothelial cell remolding and damage. Previous studies have suggested that CX3CL1 plays an important role in HPAH which is affected by oxidative stress. Ca²⁺ channel activation correlated with increasing NF-κB levels induced by ROS. Tanreqing injection (TRQ) is a traditional Chinese medicine (TCM) for acute upper respiratory tract infection and acute pneumonia. In the present study, we explored the effect of TRQ on human pulmonary artery smooth muscle cells (HPASMCs) undergoing hypoxia and feasible molecular mechanisms involved in. Cell proliferation was assayed using CCK8 kits. Immunofluorescence and western blotting along with ELISA assay were performed to investigate the effect of TRQ on hypoxia-induced ROS, Ca²⁺, hydroxyl free radicals, and the expression of Ca²⁺ channel protein TRPC1, CX3CR1, HIF-1α, NF-κBp65, and p-NF-κBp65 in HPASMCs. Human CX3CL1 and the inhibitor of TRPC1 as SKF96365 were used for further investigation. TRQ inhibited hypoxia-induced increasing cell adhesion, ROS, Ca²⁺, hydroxyl free radicals, CX3CR1, HIF-1α, NF-κBp65 activation, and even on TRPC1 expression in HPASMC which tended to be attenuated even reversed by CX3CL1. Our results suggested that TRQ might help to attenuate remodeling of HPASMC through inhibiting the ROS and TRPC1/CX3CL1 signaling pathway.

Effects of calcium‑permeable ion channels on various digestive diseases in the regulation of autophagy (Review)

Autophagy is a process of degradation and catabolism in cells. By removing damaged or dysfunctional organelles, autophagy interacts with the ubiquitin‑proteasome degradation system to jointly regulate cell function and energy homeostasis. Since autophagy plays a key role in physiology, disorders of the autophagy mechanism are associated with various diseases. Therefore, thorough understanding of the autophagy regulatory mechanism are crucially important in the diagnosis and treatment of diseases. To date, ion channels may affect the development and treatment of diseases by regulating autophagy, especially calcium‑permeable ion channels, in the process of digestive system diseases. However, the mechanism by which calcium ions and their channels regulate autophagy is still poorly understood, thus emphasizing the need for further research in this field. The present review intends to discuss the association, mechanism and application of calcium ions, their channels and autophagy in the occurrence and development of digestive system diseases.

TRPC1 Inhibits Cell Proliferation/Invasion and Is Predictive of a Better Prognosis of Esophageal Squamous Cell Carcinoma

BACKGROUND AND OBJECTIVES

In China, over 90% of esophageal cancer (EC) cases are esophageal squamous cell carcinoma (ESCC). ESCC is a frequently malignant tumor with poor prognosis despite the development of comprehensive therapeutic strategies, for which there is still a lack of effective prognostic factors. Previous studies found that the abnormal expression of TRPC1 is closely related to the proliferation, invasion, metastasis, and differentiation of various tumors. However, the relationship between TRPC1 and ESCC is currently unclear. The present study aimed to clarify the clinical significance of TRPC1 and to preliminarily assess the molecular mechanism by which TRPC1 regulates cell proliferation, migration, and invasion in ESCC.

MATERIALS AND METHODS

Immunohistochemistry (IHC) was used to determine the expression of TRPC1 and Ki-67 in 165 cases of ESCC. The correlations between TRPC1 expression and clinicopathological characteristics were determined, and both univariate and multivariate analyses were utilized to quantify the impact of TRPC1 expression on patient survival. Cell Counting Kit-8, scratch wound healing, and transwell assays were used to determine the effects of TRPC1 on proliferation, migration, and invasion in ESCC in vitro, respectively.

RESULTS

The positive expression rate of TRPC1 showed significantly decreased in ESCC (45.50%) compared with the levels in normal esophageal mucosa (NEM; 80.80%) and high-grade intraepithelial neoplasia (HGIEN; 63.20%) (P<0.001). Higher expression rate of TRPC1 was associated with low lymph node metastasis (P<0.001), high differentiation (r_s = 0.232, P=0.003), and low Ki-67 (r_s = -0.492, P<0.001). We further revealed that low expression of TRPC1 was associated with poor prognosis (Disease-free survival, DFS: 95% CI=0.545-0.845, P=0.001; Overall survival, OS: 95% CI=0.553-0.891, P=0.004). Furthermore, we showed that downregulation of TRPC1 promoted the proliferation, migration, and invasion of human esophageal squamous cell carcinoma cell line EC9706 in vitro. In contrast, overexpression of TRPC1 inhibited the proliferation, migration, and invasion of human esophageal squamous cell carcinoma cell line KYSE150 (P<0.01), in a manner at least in part mediated through the AKT/p27 pathway.

CONCLUSION

TRPC1 inhibited the proliferation, migration, and invasion of EC9706 and KYSE150 cells, at least, in part mediated through the AKT/p27 pathway in vitro. The downregulation of TRPC1 may be one of the most important molecular events in the malignant progression of ESCC. TRPC1 could be a new candidate tumor suppressor gene and a new prognostic factor of ESCC.

Expression of TRPC1 and SBEM protein in breast cancer tissue and its relationship with clinicopathological features and prognosis of patients

This study investigated the relationship of the expression of transient receptor potential channel 1 (TRPC1), small breast epithelial mucin (SBEM) in breast cancer tissues with clinical pathological features and prognosis of patients. Altogether 50 patients with breast cancer who were treated in Weifang People's hospital from April 2017 to November 2018 were selected, and the mRNA and protein differences of TRPC1 and SBEM in breast cancer patients and normal breast cancer tissues were detected by qRT-PCR and Western blot. Spearman test was used for correlation analysis. Logistic univariate and multivariate analysis were performed on the risk factors related to breast cancer metastasis in breast cancer patients. The expression of TRPC1 and SBEM in breast cancer tissues was significantly higher than that in normal breast tissues (P<0.001). The mRNA expression of TRPC1, SBEM and protein was not related to age, tumor size and tissue grade of breast cancer patients, but related to TNM stage, clinical stage and lymph node metastasis (P<0.001). The relative expression of TRPC1 was positively correlated with clinical stage of breast cancer (r=0.992, P<0.001). The relative expression of SBEM was positively correlated with the clinical stage of breast cancer (r=0.853, P<0.001). The relative expression of TRPC1 was positively correlated with TNM staging of breast cancer (r=0.860, P<0.001). The relative expression of SBEM was positively correlated with TNM staging of breast cancer (r=0.880, P<0.001). Multivariate conditional Logistic regression analysis showed that TNM staging, TRPC1, SBEM were independent risk factors for malignant breast cancer metastasis. On the contrary, expression of TRPC1 and SBEM in breast cancer tissues was up-regulated. TRPC1 and SBEM may be involved in the process of breast cancer occurrence, development and metastasis, and can be used as potential tissue biomarkers in diagnosis of breast cancer metastasis and disease assessment.

Targeting Ca2+ Signaling in the Initiation, Promotion and Progression of Hepatocellular Carcinoma

Simple Summary

Liver cancer (hepatocellular carcinoma) is a significant health burden worldwide. It is often not detected until at an advanced stage when there are few treatment options available. Changes in calcium concentrations within liver cancer cells are essential for regulating their growth, death, and migration (metastasis). Our aim was to review published papers which have identified proteins involved in calcium signaling as potential drug targets for the treatment of liver cancer. About twenty calcium signaling proteins were identified, including those involved in regulating calcium concentrations in the cytoplasm, endoplasmic reticulum and mitochondria. A few of these have turned out to be sites of action of natural products previously known to inhibit liver cancer. More systematic studies are now needed to determine which calcium signaling proteins might be used clinically for treatment of liver cancer, especially advanced stage cancers and those resistant to inhibition by current drugs.

Abstract

Hepatocellular carcinoma (HCC) is a considerable health burden worldwide and a major contributor to cancer-related deaths. HCC is often not noticed until at an advanced stage where treatment options are limited and current systemic drugs can usually only prolong survival for a short time. Understanding the biology and pathology of HCC is a challenge, due to the cellular and anatomic complexities of the liver. While not yet fully understood, liver cancer stem cells play a central role in the initiation and progression of HCC and in resistance to drugs. There are approximately twenty Ca²⁺-signaling proteins identified as potential targets for therapeutic treatment at different stages of HCC. These potential targets include inhibition of the self-renewal properties of liver cancer stem cells; HCC initiation and promotion by hepatitis B and C and non-alcoholic fatty liver disease (principally involving reduction of reactive oxygen species); and cell proliferation, tumor growth, migration and metastasis. A few of these Ca²⁺-signaling pathways have been identified as targets for natural products previously known to reduce HCC. Promising Ca²⁺-signaling targets include voltage-operated Ca²⁺ channel proteins (liver cancer stem cells), inositol trisphosphate receptors, store-operated Ca²⁺ entry, TRP channels, sarco/endoplasmic reticulum (Ca²⁺+Mg²⁺) ATP-ase and Ca²⁺/calmodulin-dependent protein kinases. However, none of these Ca²⁺-signaling targets has been seriously studied any further than laboratory research experiments. The future application of more systematic studies, including genomics, gene expression (RNA-seq), and improved knowledge of the fundamental biology and pathology of HCC will likely reveal new Ca²⁺-signaling protein targets and consolidate priorities for those already identified.

Development of an immune-related prognostic index associated with hepatocellular carcinoma

Liver hepatocellular carcinoma (LIHC), an inflammation-associated cancer induced by a variety of etiological factors, is still one of the most prevalent and lethal cancers in human population. In this study, the expression profiles of immune-related genes (IRGs) were integrated with the overall survival (OS) of 378 LIHC patients based on the Cancer Genome Atlas (TCGA) dataset. Moreover, the differentially expressed and survival related IRGs among LIHC patients were predicted through the computational difference algorithm and COX regression analysis. As a result, 7 genes, including HSPA4, S100A10, FABP6, CACYBP, HDAC1, FCGR2B and SHC1, were retrieved to construct a predictive model associated with the overall survival (OS) of LIHC patients. Typically, the as-constructed model performed moderately in predicting prognosis, which was also correlated with tumor grade. Functional enrichment analysis revealed that the genes of high-risk group were actively involved in mRNA binding and the spliceosome pathway. Intriguingly, the prognostic index established based on IRGs reflected infiltration by multiple types of immunocytes. Our findings screen several IRGs with clinical significance, reveal the drivers of immune repertoire, and illustrate the importance of a personalized, IRG-based immune signature in LIHC recognition, surveillance, and prognosis prediction.

The Role of TRPC1 in Modulating Cancer Progression

Calcium ions (Ca²⁺) play an important role as second messengers in regulating a plethora of physiological and pathological processes, including the progression of cancer. Several selective and non-selective Ca²⁺-permeable ion channels are implicated in mediating Ca²⁺ signaling in cancer cells. In this review, we are focusing on TRPC1, a member of the TRP protein superfamily and a potential modulator of store-operated Ca²⁺ entry (SOCE) pathways. While TRPC1 is ubiquitously expressed in most tissues, its dysregulated activity may contribute to the hallmarks of various types of cancers, including breast cancer, pancreatic cancer, glioblastoma multiforme, lung cancer, hepatic cancer, multiple myeloma, and thyroid cancer. A range of pharmacological and genetic tools have been developed to address the functional role of TRPC1 in cancer. Interestingly, the unique role of TRPC1 has elevated this channel as a promising target for modulation both in terms of pharmacological inhibition leading to suppression of tumor growth and metastasis, as well as for agonistic strategies eliciting Ca²⁺ overload and cell death in aggressive metastatic tumor cells.

FUS/circ_002136/miR-138-5p/SOX13 feedback loop regulates angiogenesis in Glioma

Background

Angiogenesis plays a critical role in the progression of glioma. Previous studies have indicated that RNA-binding proteins (RBPs) interact with RNAs and participate in the regulation of the malignant behaviors of tumors. As a type of endogenous non-coding RNAs, circular RNAs (circRNAs) are abnormally expressed in various cancers and are involved in diverse tumorigeneses including angiogenesis.

Methods

The expression levels of FUS, circ_002136, miR-138-5p, SOX13, and SPON2 were determined using quantitative real-time PCR (qRT-PCR) and western blot. Transient cell transfection was performed using the Lipofectamine 3000 reagent. The RNA-binding protein immunoprecipitation (RNA-IP) and the RNA pull-down assays were used to detect the interaction between FUS and circ_002136. The dual-luciferase reporter assay system was performed to detect the binding sites of circ_002136 and miR-138-5p, miR-138-5p and SOX13. The chromatin immunoprecipitation (ChIP) assays were used to examine the interactions between transcription factor SOX13 and its target proteins .

Results

We demonstrated that down-regulation of FUS or circ_002136 dramatically inhibited the viability, migration and tube formation of U87 glioma-exposed endothelial cells (GECs). MiR-138-5p was down-regulated in GECs and circ_002136 functionally targeted miR-138-5p in an RNA-induced silencing complex (RISC). Inhibition of circ_002136, combined with the restoration of miR-138-5p, robustly reduced the angiogenesis of GECs. As a target gene of miR-138-5p, SOX13 was overexpressed in GECs and was proved to be involved in circ_002136 and miR-138-5p-mediated angiogenesis in gliomas. In addition, we found that SOX13 was directly associated with and activated the SPON2 promoter, thereby up-regulating the expression of SPON2 at the transcriptional level. Knockdown of SPON2 suppressed the angiogenesis in GECs. More important, SOX13 activated the FUS promoter and increased its expression, forming a feedback loop.

Conclusion

Our data suggests that the feedback loop of FUS/circ_002136/miR-138-5p/SOX13 played a crucial role in the regulation of angiogenesis in glioma. This also provides a potential target and an alternative strategy for combined glioma therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1065-7) contains supplementary material, which is available to authorized users.

Inhibition of Orai1-mediated Ca2+ entry enhances chemosensitivity of HepG2 hepatocarcinoma cells to 5-fluorouracil

Increasing evidence supports that activation of store-operated Ca²⁺ entry (SOCE) is implicated in the chemoresistance of cancer cells subjected to chemotherapy. However, the molecular mechanisms underlying chemoresistance are not well understood. In this study, we aim to investigate whether 5-FU induces hepatocarcinoma cell death through regulating Ca²⁺ -dependent autophagy. [Ca²⁺ ]_i was measured using fura2/AM dye. Protein expression was determined by Western blotting and immunohistochemistry. We found that 5-fluorouracil (5-FU) induced autophagic cell death in HepG2 hepatocarcinoma cells by inhibiting PI3K/AKT/mTOR pathway. Orai1 expression was obviously elevated in hepatocarcinoma tissues. 5-FU treatment decreased SOCE and Orai1 expressions, but had no effects on Stim1 and TRPC1 expressions. Knockdown of Orai1 or pharmacological inhibition of SOCE enhanced 5-FU-induced inhibition of PI3K/AKT/mTOR pathway and potentiated 5-FU-activated autophagic cell death. On the contrary, ectopic overexpression of Orai1 antagonizes 5-FU-induced autophagy and cell death. Our findings provide convincing evidence to show that Orai1 expression is increased in hepatocarcinoma tissues. 5-FU can induce autophagic cell death in HepG2 hepatocarcinoma cells through inhibition of SOCE via decreasing Orai1 expression. These findings suggest that Orai1 expression is a predictor of 5-FU sensitivity for hepatocarcinoma treatment and blockade of Orai1-mediated Ca²⁺ entry may be a promising strategy to sensitize hepatocarcinoma cells to 5-FU treatment.