Orai3 Calcium Channel Regulates Breast Cancer Cell Migration through Calcium-Dependent and -Independent Mechanisms

Plasma membrane SK2 channel activity regulates migration and chemosensitivity of high-grade serous ovarian cancer cells

No data are currently available on the functional role of small conductance Ca2+-activated K+ channels (SKCa) in ovarian cancer. Here, we characterized the role of SK2 (KCa2.2) in ovarian cancer cell migration and chemosensitivity. Using the selective non-cell-permeant SK2 inhibitor Lei-Dab7, we identified functional SK2 channels at the plasma membrane, regulating store-operated Ca2+ entry (SOCE) in both cell lines tested (COV504 and OVCAR3). Silencing KCNN2 with short interfering RNA (siRNA), or blocking SK2 activity with Lei-Dab7, decreased cell migration. The more robust effect of KCNN2 knockdown compared to Lei-Dab7 treatment suggested the involvement of functional intracellular SK2 channels in both cell lines. In cells treated with lysophosphatidic acid (LPA), an ovarian cancer biomarker of progression, SK2 channels are a key player of LPA pro-migratory activity but their role in SOCE is abolished. Concerning chemotherapy, SK2 inhibition increased chemoresistance to Taxol® and low KCNN2 mRNA expression was associated with the worst prognosis for progression-free survival in patients with serous ovarian cancer. The dual roles of SK2 mean that SK2 activators could be used as an adjuvant chemotherapy to potentiate treatment efficacy and SK2 inhibitors could be administrated as monotherapy to limit cancer cell dissemination.

Pivotal role of the ORAI3-STIM2 complex in the control of mitotic death and prostate cancer cell cycle progression

Prostate cancer (PCa) represents one of the most frequent diagnosed cancer in males worldwide. Due to routine screening tests and the efficiency of available treatments, PCa-related deaths have significantly decreased over the past decades. However, PCa remains a critical threat if detected at a late stage in which, cancer cells would have already detached from the primary tumor to spread and invade other parts of the body. Calcium (Ca2+) channels and their protein regulators are now considered as hallmarks of cancer and some of them have been well examined in PCa. Among these Ca2+ channels, isoform 3 of the ORAI channel family has been shown to regulate the proliferation of PCa cells via the Arachidonic Acid-mediated Ca2+ entry, requiring the involvement of STIM1 (Stromal Interaction Molecule 1). Still, no study has yet demonstrated a role of the "neglected" STIM2 isoform in PCa or if it may interact with ORAI3 to promote an oncogenic behavior. In this study, we demonstrate that ORAI3 and STIM2 are upregulated in human PCa tissues. In old KIMAP (Knock-In Mouse Prostate Adenocarcinoma) mice, ORAI3 and STIM2 mRNA levels were significantly higher than ORAI1 and STIM1. In vitro, we show that ORAI3-STIM2 interact under basal conditions in PC-3 cells. ORAI3 silencing increased Store Operated Ca2+ Entry (SOCE) and induced a significant increase of the cell population in G2/M phase of the cell cycle, consistent with the role of ORAI3 as a negative regulator of SOCE. Higher expression levels of CDK1-Y15/Cyclin B1 were detected and mitotic arrest-related death occurred after ORAI3 silencing, which resulted in activating Bax/Bcl-2-mediated apoptotic pathway and caspase-8 activation and cleavage. STIM2 and ORAI3 expression increased in M phase while STIM1 expression and SOCE amplitude significantly decreased. Taken together, ORAI3 -STIM2 complex allows a successful progression through mitosis of PCa cells by evading mitotic catastrophe.

Orai3 Calcium Channel Contributes to Oral/Oropharyngeal Cancer Stemness through the Elevation of ID1 Expression

Emerging evidence indicates that intracellular calcium (Ca2+) levels and their regulatory proteins play essential roles in normal stem cell proliferation and differentiation. Cancer stem-like cells (CSCs) are subpopulations of cancer cells that retain characteristics similar to stem cells and play an essential role in cancer progression. Recent studies have reported that the Orai3 calcium channel plays an oncogenic role in human cancer. However, its role in CSCs remains underexplored. In this study, we explored the effects of Orai3 in the progression and stemness of oral/oropharyngeal squamous cell carcinoma (OSCC). During the course of OSCC progression, the expression of Orai3 exhibited a stepwise augmentation. Notably, Orai3 was highly enriched in CSC populations of OSCC. Ectopic Orai3 expression in non-tumorigenic immortalized oral epithelial cells increased the intracellular Ca2+ levels, acquiring malignant growth and CSC properties. Conversely, silencing of the endogenous Orai3 in OSCC cells suppressed the CSC phenotype, indicating a pivotal role of Orai3 in CSC regulation. Moreover, Orai3 markedly increased the expression of inhibitor of DNA binding 1 (ID1), a stemness transcription factor. Orai3 and ID1 exhibited elevated expression within CSCs compared to their non-CSC counterparts, implying the functional importance of the Orai3/ID1 axis in CSC regulation. Furthermore, suppression of ID1 abrogated the CSC phenotype in the cell with ectopic Orai3 overexpression and OSCC. Our study reveals that Orai3 is a novel functional CSC regulator in OSCC and further suggests that Orai3 plays an oncogenic role in OSCC by promoting cancer stemness via ID1 upregulation.

ZXDC enhances cervical cancer metastasis through IGF2BP3-mediated activation of RhoA/ROCK signaling

Metastasis in cervical cancer (CC) has a significant negative impact on patient survival, highlighting the urgent need for investigation in this area. In this study, we identified significant overexpression of zinc finger, X-linked, duplicated family member C (ZXDC) in CC tissue with metastasis, which correlates with poor outcomes for CC patients. We observed that overexpression of ZXDC promotes, while silencing of ZXDC inhibits the metastasis of CC cells both in vitro and in vivo. Additionally, our research demonstrated that ZXDC activated RhoA/ROCK signaling pathway, leading to enhanced cytoskeleton remodeling in CC cells. Besides, we found that IGF2BP3 plays an essential role in the activation of ZXDC on the RhoA/ROCK signaling pathway by stabilizing RhoA mRNA. These findings reveal a mechanism whereby ZXDC promotes the cervical cancer metastasis by targeting IGF2BP3/RhoA/ROCK pathway.

Calcium signal modulation in breast cancer aggressiveness

Breast cancer (BC) is the second most common cancer and cause of death in women. The aggressive subtypes including triple negative types (TNBCs) show a resistance to chemotherapy, impaired immune system, and a worse prognosis. From a histological point of view, TNBCs are deficient in oestrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2⁺) expression. Many studies reported an alteration in the expression of calcium channels, calcium binding proteins and pumps in BC that promote proliferation, survival, resistance to chemotherapy, and metastasis. Moreover, Ca²⁺ signal remodeling and calcium transporters expression have been associated to TNBCs and HER2⁺ BC subtypes. This review provides insight into the underlying alteration of the expression of calcium-permeable channels, pumps, and calcium dependent proteins and how this alteration plays an important role in promoting metastasis, metabolic switching, inflammation, and escape to chemotherapy treatment and immune surveillance in aggressive BC including TNBCs models and highly metastatic BC tumors.

Role of Orai-family channels in the activation and regulation of transcriptional activity

Store operated Ca²⁺ entry (SOCE) is a cornerstone for the maintenance of intracellular Ca²⁺ homeostasis and the regulation of a variety of cellular functions. SOCE is mediated by STIM and Orai proteins following the activation of inositol 1,4,5-trisphosphate receptors. Then, a reduction of the endoplasmic reticulum intraluminal Ca²⁺ concentration is sensed by STIM proteins, which undergo a conformational change and activate plasma membrane Ca²⁺ channels comprised by Orai proteins. STIM1/Orai-mediated Ca²⁺ signals are finely regulated and modulate the activity of different transcription factors, including certain isoforms of the nuclear factor of activated T-cells, the cAMP-response element binding protein, the nuclear factor κ-light chain-enhancer of activated B cells, c-fos, and c-myc. These transcription factors associate SOCE with a plethora of signaling events and cellular functions. Here we provide an overview of the current knowledge about the role of Orai channels in the regulation of transcription factors through Ca²⁺ -dependent signaling pathways.

Functional and clinical characteristics of focal adhesion kinases in cancer progression

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase and an adaptor protein that primarily regulates adhesion signaling and cell migration. FAK promotes cell survival in response to stress. Increasing evidence has shown that at the pathological level, FAK is highly expressed in multiple tumors in several systems (including lung, liver, gastric, and colorectal cancers) and correlates with tumor aggressiveness and patient prognosis. At the molecular level, FAK promotes tumor progression mainly by altering survival signals, invasive capacity, epithelial-mesenchymal transition, the tumor microenvironment, the Warburg effect, and stemness of tumor cells. Many effective drugs have been developed based on the comprehensive role of FAK in tumor cells. In addition, its potential as a tumor marker cannot be ignored. Here, we discuss the pathological and pre-clinical evidence of the role of FAK in cancer development; we hope that these findings will assist in FAK-based clinical studies.

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.

Recent Developments on the Roles of Calcium Signals and Potential Therapy Targets in Cervical Cancer

Intracellular calcium (Ca²⁺) concentration ([Ca²⁺]i) is implicated in proliferation, invasion, and metastasis in cancerous tissues. A variety of oncologic therapies and some candidate drugs induce their antitumor effects (in part or in whole) through the modulation of [Ca²⁺]i. Cervical cancer is one of most common cancers among women worldwide. Recently, major research advances relating to the Ca²⁺ signals in cervical cancer are emerging. In this review, we comprehensively describe the current progress concerning the roles of Ca²⁺ signals in the occurrence, development, and prognosis of cervical cancer. It will enhance our understanding of the causative mechanism of Ca²⁺ signals in cervical cancer and thus provide new sights for identifying potential therapeutic targets for drug discovery.

Crosstalk between Ca2+ Signaling and Cancer Stemness: The Link to Cisplatin Resistance

In the fight against cancer, therapeutic strategies using cisplatin are severely limited by the appearance of a resistant phenotype. While cisplatin is usually efficient at the beginning of the treatment, several patients endure resistance to this agent and face relapse. One of the reasons for this resistant phenotype is the emergence of a cell subpopulation known as cancer stem cells (CSCs). Due to their quiescent phenotype and self-renewal abilities, these cells have recently been recognized as a crucial field of investigation in cancer and treatment resistance. Changes in intracellular calcium (Ca²⁺) through Ca²⁺ channel activity are essential for many cellular processes such as proliferation, migration, differentiation, and survival in various cell types. It is now proved that altered Ca²⁺ signaling is a hallmark of cancer, and several Ca²⁺ channels have been linked to CSC functions and therapy resistance. Moreover, cisplatin was shown to interfere with Ca²⁺ homeostasis; thus, it is considered likely that cisplatin-induced aberrant Ca²⁺ signaling is linked to CSCs biology and, therefore, therapy failure. The molecular signature defining the resistant phenotype varies between tumors, and the number of resistance mechanisms activated in response to a range of pressures dictates the global degree of cisplatin resistance. However, if we can understand the molecular mechanisms linking Ca²⁺ to cisplatin-induced resistance and CSC behaviors, alternative and novel therapeutic strategies could be considered. In this review, we examine how cisplatin interferes with Ca²⁺ homeostasis in tumor cells. We also summarize how cisplatin induces CSC markers in cancer. Finally, we highlight the role of Ca²⁺ in cancer stemness and focus on how they are involved in cisplatin-induced resistance through the increase of cancer stem cell populations and via specific pathways.

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.

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.