Calcium signalling and breast cancer

Calmodulin 2 expression is associated with poor prognosis in breast cancer

BACKGROUND

Calmodulin 2 (CALM2) belongs to the highly conserved calcium-binding protein family, implicated in the pathogenesis of various malignant tumors. However, its involvement in breast cancer (BRCA) remains unclear. This study aimed to examine CALM2 expression in BRCA and its associations with prognosis, clinicopathological features, protein-protein interactions, and immune cell infiltration.

MATERIALS AND METHODS

Online bioinformatics tools were employed to assess CALM2 expression and its clinical relevance in BRCA. Western blotting and immunohistochemistry were utilized to evaluate CALM2 expression in BRCA cell lines and tissues. Logistic regression was applied to analyze the relationship between CALM2 expression levels and clinicopathological parameters. Transwell assay was performed to validate the role of CALM2 in BRCA migration and invasion.

RESULTS

CALM2 expression was significantly elevated in BRCA, with increased levels predicting poor overall survival (OS) and disease-free survival (DFS). Moreover, high CALM2 expression correlated with poorer DFS specifically in triple-negative breast cancer (TNBC). CALM2 expression in BRCA showed significant associations with lymph node metastasis, TP53 mutation status, and menopause status. Silencing CALM2 in BRCA cells demonstrated inhibition of cell migration and invasion in vitro.

CONCLUSIONS

CALM2 is overexpressed in BRCA and its upregulation is significantly correlated with poor patient prognosis. Elevated CALM2 expression holds promise as a potential molecular marker for predicting poor survival and as a therapeutic target in BRCA.

Micronutrient Status and Breast Cancer: A Narrative Review

Breast cancer is one of the most common cancers worldwide, at the same time being one of the most prevalent causes of women's death. Many factors such as alcohol, weight fluctuations, or hormonal replacement therapy can potentially contribute to breast cancer development and progression. Another important factor in breast cancer onset includes micronutrient status. In this narrative review, we analyzed 23 micronutrients and their possible influence on breast cancer onset and progression. Further, the aim of this study was to investigate the impact of micronutrient status on the prevention of breast cancer and its possible influence on various therapeutic pathways. We researched meta-analyses, systemic and narrative reviews, retrospective studies, as well as original studies on human and animal models. The results of these studies indicate a possible correlation between the different levels of micronutrients and a decreased risk of breast cancer as well as a better survival rate. However, further studies are necessary to establish adequate doses of supplementation of the chosen micronutrients and the exact mechanisms of micronutrient impact on breast cancer therapy.

Evaluation of IP3R3 Gene Silencing Effect on Pyruvate Dehydrogenase (PDH) Enzyme Activity in Breast Cancer Cells with and Without Estrogen Receptor

Background

Inositol 1,4,5-trisphosphate receptor (IP3R), a critical calcium ion (Ca2+) regulator, plays a vital role in breast cancer (BC) metabolism. Dysregulated IP3R in BC cells can drive abnormal growth or cell death. Estradiol increases IP3R type 3 (IP3R3) levels in BC, promoting cell proliferation and metabolic changes, including enhanced pyruvate dehydrogenase (PDH) activity, which, when reduced, leads to cell apoptosis. The study silenced IP3R3 to assess its impact on PDH.

Materials and Methods

The study used IP3R3 small interfering RNA (siRNA) to target Michigan Cancer Foundation-7 (MCF-7) and MDA-MB-231 cell lines. Transfection success was confirmed by flow cytometry. Cell viability and gene silencing were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and real-time quantitative polymerase chain reaction (PCR) assays. Protein expression and cellular activity were analyzed through western blotting and PDH activity measurement.

Results

Transfecting MCF-7 and MDA-MB-231 cells with IP3R3 siRNA achieved a 65% transfection rate without significant toxicity. IP3R3 gene silencing effectively reduced IP3R3 messenger RNA (mRNA) and protein levels in both cell lines, leading to decreased PDH enzyme activity, especially in MDA-MB-231 cells.

Conclusion

The study highlights a link between high IP3R3 gene silencing and reduced PDH activity, with higher IP3R3 expression in estrogen-independent (MDA-MB-231) compared to estrogen-dependent (MCF-7) cell lines. This suggests a potential impact on BC metabolism and tumor growth via regulation of PDH activity.

ASIC1a contributes to the epithelial-mesenchymal transformation of breast cancer by activating the Ca2+ /β-catenin pathway

Breast cancer is the most common cancer in the world, with metastasis being one of the leading causes of death among patients. The acidic environment of breast cancer tissue promotes tumor cell invasion and migration by inducing epithelial-mesenchymal transformation (EMT) in tumor cells, but the exact mechanisms are not yet fully understood. This study investigated the expression of acid-sensitive ion channel 1a (ASIC1a) in breast cancer tissue samples and explored the mechanisms by which ASIC1a mediates the promotion of EMT in breast cancer cells in an acidic microenvironment through in vivo and in vitro experiments. The results showed that first, the expression of ASIC1a was significantly upregulated in breast cancer tissue and was correlated with the TNM (tumor node metastasis) staging of breast cancer. Furthermore, ASIC1a expression was higher in tumors with lymph node metastasis than in those without. Second, the acidic microenvironment promoted [Ca2+ ]i influx via ASIC1a activation and regulated the expression of β-catenin, Vimentin, and E-cadherin, thus promoting EMT in breast cancer cells. Inhibition of ASIC1a activation with PcTx-1 could suppress EMT in breast cancer cells. Finally, in vivo studies also showed that inhibition of ASIC1a could reduce breast cancer metastasis, invasion, and EMT. This study suggests that ASIC1a expression is associated with breast cancer staging and metastasis. Therefore, ASIC1a may become a new breast cancer biomarker, and the elucidation of the mechanism by which ASIC1a promotes EMT in breast cancer under acidic microenvironments provides evidence for the use of ASIC1a as a molecular target for breast cancer treatment.

CLEC19A overexpression inhibits tumor cell proliferation/migration and promotes apoptosis concomitant suppression of PI3K/AKT/NF-κB signaling pathway in glioblastoma multiforme

BACKGROUND

GBM is the most frequent malignant primary brain tumor in humans. The CLEC19A is a member of the C-type lectin family, which has a high expression in brain tissue. Herein, we sought to carry out an in-depth analysis to pinpoint the role of CLEC19A expression in GBM.

METHODS

To determine the localization of CLEC19A, this protein was detected using Western blot, Immunocytochemistry/Immunofluorescence, and confocal microscopy imaging. CLEC19A expression in glioma cells and tissues was evaluated by qRT-PCR. Cell viability, proliferation, migration, and apoptosis were examined through MTT assay, CFSE assay, colony formation, wound healing assay, transwell test, and flow cytometry respectively after CLEC19A overexpression. The effect of CLEC19A overexpression on the PI3K/AKT/NF-κB signaling pathway was investigated using Western blot. An in vivo experiment substantiated the in vitro results using the glioblastoma rat models.

RESULTS

Our in-silico analysis using TCGA data and measuring CLEC19A expression level by qRT-PCR determined significantly lower expression of CLEC19A in human glioma tissues compared to healthy brain tissues. By employment of ICC/IF, confocal microscopy imaging, and Western blot we could show that CLEC19A is plausibly a secreted protein. Results obtained from several in vitro readouts showed that CLEC19A overexpression in U87 and C6 glioma cell lines is associated with the inhibition of cell proliferation, viability, and migration. Further, qRT-PCR and Western blot analysis showed CLEC19A overexpression could reduce the expression levels of PI3K, VEGFα, MMP2, and NF-κB and increase PTEN, TIMP3, RECK, and PDCD4 expression levels in glioma cell lines. Furthermore, flow cytometry results revealed that CLEC19A overexpression was associated with significant cell cycle arrest and promotion of apoptosis in glioma cell lines. Interestingly, using a glioma rat model we could substantiate that CLEC19A overexpression suppresses glioma tumor growth.

CONCLUSIONS

To our knowledge, this is the first report providing in-silico, molecular, cellular, and in vivo evidences on the role of CLEC19A as a putative tumor suppressor gene in GBM. These results enhance our understanding of the role of CLEC19A in glioma and warrant further exploration of CLEC19A as a potential therapeutic target for GBM.

Tamoxifen Activates Transcription Factor EB and Triggers Protective Autophagy in Breast Cancer Cells by Inducing Lysosomal Calcium Release: A Gateway to the Onset of Endocrine Resistance

Among the several mechanisms accounting for endocrine resistance in breast cancer, autophagy has emerged as an important player. Previous reports have evidenced that tamoxifen (Tam) induces autophagy and activates transcription factor EB (TFEB), which regulates the expression of genes controlling autophagy and lysosomal biogenesis. However, the mechanisms by which this occurs have not been elucidated as yet. This investigation aims at dissecting how TFEB is activated and contributes to Tam resistance in luminal A breast cancer cells. TFEB was overexpressed and prominently nuclear in Tam-resistant MCF7 cells (MCF7-TamR) compared with their parental counterpart, and this was not dependent on alterations of its nucleo-cytoplasmic shuttling. Tam promoted the release of lysosomal Ca2+ through the major transient receptor potential cation channel mucolipin subfamily member 1 (TRPML1) and two-pore channels (TPCs), which caused the nuclear translocation and activation of TFEB. Consistently, inhibiting lysosomal calcium release restored the susceptibility of MCF7-TamR cells to Tam. Our findings demonstrate that Tam drives the nuclear relocation and transcriptional activation of TFEB by triggering the release of Ca2+ from the acidic compartment, and they suggest that lysosomal Ca2+ channels may represent new druggable targets to counteract the onset of autophagy-mediated endocrine resistance in luminal A breast cancer cells.

UBE3B promotes breast cancer progression by antagonizing HIF-2α degradation

Mutations in E3 ubiquitin ligase UBE3B have been linked to Kaufman Oculocerebrofacial Syndrome (KOS). Accumulating evidence indicates that UBE3B may play an important role in cancer. However, the precise role of UBE3B in cancer and the underlying mechanism remain largely uncharted. Here, we reported that UBE3B is an E3 ligase for hypoxia-inducible factor 2α (HIF-2α). Mechanically, UBE3B physically interacts with HIF-2α and promotes its lysine 63 (K63)-linked polyubiquitination, thereby inhibiting the Von Hippel-Lindau (VHL) E3 ligase complex-mediated HIF-2α degradation. UBE3B depletion inhibits breast cancer cell proliferation, colony formation, migration, and invasion in vitro and suppresses breast tumor growth and lung metastasis in vivo. We further identified K394, K497, and K503 of HIF-2α as key ubiquitination sites for UBE3B. K394/497/503R mutation of HIF-2α dramatically abolishes UBE3B-mediated breast cancer growth and lung metastasis. Intriguingly, the protein levels of UBE3B are upregulated and positively correlated with HIF-2α protein levels in breast cancer tissues. These findings uncover a critical mechanism underlying the role of UBE3B in HIF-2α regulation and breast cancer progression.

Synergistic ROS generation and directional overloading of endogenous calcium induce mitochondrial dysfunction in living cells

Taking advantage of endogenous Ca2+ to upregulate intramitochondrial Ca2+ level has become a powerful mean for mitochondrial dysfunction-mediated tumor therapy. However, the Ca2+ entered into mitochondria is limited ascribing to the uncontrollability and non-selectivity of endogenous Ca2+ transport. It remains a great challenge to make the maximum use of endogenous Ca2+ to ensure sufficient Ca2+ overloading in mitochondria. Herein, we smartly fabricate an intracellular Ca2+ directional transport channel to selectively transport endogenous Ca2+ from endoplasmic reticulum (ER) to mitochondria based on cascade release nanoplatform ABT-199@liposomes/doxorubicin@FeIII-tannic acid (ABT@Lip/DOX@Fe-TA). In tumor acidic microenvironment, Fe3+ ions are firstly released and reduced by tannic acid (TA) to Fe2+ for ROS generation. Subsequently, under the NIR light irradiation, the released ABT-199 molecules combine with ROS contribute to the formation of IP3R-Grp75-VDAC1 channel between ER and mitochondria, thus Ca2+ ions are directionally delivered and intramitochondrial Ca2+ level is significantly upregulated. The synergetic ROS generation and mitochondrial Ca2+ overloading effectively intensifies mitochondrial dysfunction, thereby achieving efficient tumor inhibition. This work presents a new insight and promising avenue for endogenous Ca2+-involved tumor therapies.

Calcium Homeostasis in the Development of Resistant Breast Tumors

Cancer is one of the main health problems worldwide. Only in 2020, this disease caused more than 19 million new cases and almost 10 million deaths, with breast cancer being the most diagnosed worldwide. Today, despite recent advances in breast cancer treatment, a significant percentage of patients will either not respond to therapy or will eventually experience lethal progressive disease. Recent studies highlighted the involvement of calcium in the proliferation or evasion of apoptosis in breast carcinoma cells. In this review, we provide an overview of intracellular calcium signaling and breast cancer biology. We also discuss the existing knowledge on how altered calcium homeostasis is implicated in breast cancer development, highlighting the potential utility of Ca²⁺ as a predictive and prognostic biomarker, as well as its potential for the development of new pharmacological treatments to treat the disease.

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.

Sodium regulates PLC and IP3 R-mediated calcium signaling in invasive breast cancer cells

Intracellular Ca2+ signaling and Na+ homeostasis are inextricably linked via ion channels and co-transporters, with alterations in the concentration of one ion having profound effects on the other. Evidence indicates that intracellular Na+ concentration ([Na+ ]i ) is elevated in breast tumors, and that aberrant Ca2+ signaling regulates numerous key cancer hallmark processes. The present study therefore aimed to determine the effects of Na+ depletion on intracellular Ca2+ handling in metastatic breast cancer cell lines. The relationship between Na+ and Ca2+ was probed using fura-2 and SBFI fluorescence imaging and replacement of extracellular Na+ with equimolar N-methyl-D-glucamine (0Na+ /NMDG) or choline chloride (0Na+ /ChoCl). In triple-negative MDA-MB-231 and MDA-MB-468 cells and Her2+ SKBR3 cells, but not ER+ MCF-7 cells, 0Na+ /NMDG and 0Na+ /ChoCl resulted in a slow, sustained depletion in [Na+ ]i that was accompanied by a rapid and sustained increase in intracellular Ca2+ concentration ([Ca2+ ]i ). Application of La3+ in nominal Ca2+ -free conditions had no effect on this response, ruling out reverse-mode NCX activity and Ca2+ entry channels. Moreover, the Na+ -linked [Ca2+ ]i increase was independent of membrane potential hyperpolarization (NS-1619), but was inhibited by pharmacological blockade of IP3 receptors (2-APB), phospholipase C (PLC, U73122) or following depletion of endoplasmic reticulum Ca2+ stores (cyclopiazonic acid). Thus, Na+ is linked to PLC/IP3 -mediated activation of endoplasmic reticulum Ca2+ release in metastatic breast cancer cells and this may have an important role in breast tumors where [Na+ ]i is perturbed.

Potential Carcinogens in Makeup Cosmetics

Facial makeup cosmetics are commonly used products that are applied to the skin, and their ingredients come into contact with it for many years. Consequently, they should only contain substances that are considered safe or used within an allowable range of established concentrations. According to current European laws, all cosmetics approved for use should be entirely safe for their users, and the responsibility for this lies with manufacturers, distributors, and importers. However, the use of cosmetics can be associated with undesirable effects due to the presence of certain chemical substances. An analysis of 50 random facial makeup cosmetics commercially available on the European Union market and manufactured in six European countries was carried out, concerning the presence of substances with potential carcinogenic properties, as described in recent years in the literature. Nine types of facial makeup cosmetics were selected, and their compositions, as declared on the labels, were analyzed. The carcinogens were identified with information present in the European CosIng database and according to the Insecticide Resistance Action Committee's (IRAC) classification. As a result, the following potential carcinogens were identified: parabens (methylparaben, propylparaben, butylparaben, and ethylparaben), ethoxylated compounds (laureth-4, lautreth-7, or ethylene glycol polymers known as PEG), formaldehyde donors (imidazolidinyl urea, quaternium 15, and DMDM hydantoin), and ethanolamine and their derivatives (triethanolamine and diazolidinyl urea), as well as carbon and silica. In conclusion, all of the analyzed face makeup cosmetics contain potential carcinogenic substances. The literature review confirmed the suppositions regarding the potential carcinogenic effects of selected cosmetic ingredients. Therefore, it seems necessary to carry out studies on the long-term exposure of compounds present in cosmetics and perhaps introduce stricter standards and laws regulating the potential presence of carcinogens and their activity in cosmetics.

Targeting Breast Cancer: An Overlook on Current Strategies

Breast cancer (BC) is one of the most widely diagnosed cancers and a leading cause of cancer death among women worldwide. Globally, BC is the second most frequent cancer and first most frequent gynecological one, affecting women with a relatively low case-mortality rate. Surgery, radiotherapy, and chemotherapy are the main treatments for BC, even though the latter are often not aways successful because of the common side effects and the damage caused to healthy tissues and organs. Aggressive and metastatic BCs are difficult to treat, thus new studies are needed in order to find new therapies and strategies for managing these diseases. In this review, we intend to give an overview of studies in this field, presenting the data from the literature concerning the classification of BCs and the drugs used in therapy for the treatment of BCs, along with drugs in clinical studies.

Elevation of Cytoplasmic Calcium Suppresses Microtentacle Formation and Function in Breast Tumor Cells

Cytoskeletal remodeling in circulating tumor cells (CTCs) facilitates metastatic spread. Previous oncology studies examine sustained aberrant calcium (Ca²⁺) signaling and cytoskeletal remodeling scrutinizing long-term phenotypes such as tumorigenesis and metastasis. The significance of acute Ca²⁺ signaling in tumor cells that occur within seconds to minutes is overlooked. This study investigates rapid cytoplasmic Ca²⁺ elevation in suspended cells on actin and tubulin cytoskeletal rearrangements and the metastatic microtentacle (McTN) phenotype. The compounds Ionomycin and Thapsigargin acutely increase cytoplasmic Ca²⁺, suppressing McTNs in the metastatic breast cancer cell lines MDA-MB-231 and MDA-MB-436. Functional decreases in McTN-mediated reattachment and cell clustering during the first 24 h of treatment are not attributed to cytotoxicity. Rapid cytoplasmic Ca²⁺ elevation was correlated to Ca²⁺-induced actin cortex contraction and rearrangement via myosin light chain 2 and cofilin activity, while the inhibition of actin polymerization with Latrunculin A reversed Ca²⁺-mediated McTN suppression. Preclinical and phase 1 and 2 clinical trial data have established Thapsigargin derivatives as cytotoxic anticancer agents. The results from this study suggest an alternative molecular mechanism by which these compounds act, and proof-of-principle Ca²⁺-modulating compounds can rapidly induce morphological changes in free-floating tumor cells to reduce metastatic phenotypes.

The distinguishing electrical properties of cancer cells

In recent decades, medical research has been primarily focused on the inherited aspect of cancers, despite the reality that only 5-10% of tumours discovered are derived from genetic causes. Cancer is a broad term, and therefore it is inaccurate to address it as a purely genetic disease. Understanding cancer cells' behaviour is the first step in countering them. Behind the scenes, there is a complicated network of environmental factors, DNA errors, metabolic shifts, and electrostatic alterations that build over time and lead to the illness's development. This latter aspect has been analyzed in previous studies, but how the different electrical changes integrate and affect each other is rarely examined. Every cell in the human body possesses electrical properties that are essential for proper behaviour both within and outside of the cell itself. It is not yet clear whether these changes correlate with cell mutation in cancer cells, or only with their subsequent development. Either way, these aspects merit further investigation, especially with regards to their causes and consequences. Trying to block changes at various levels of occurrence or assisting in their prevention could be the key to stopping cells from becoming cancerous. Therefore, a comprehensive understanding of the current knowledge regarding the electrical landscape of cells is much needed. We review four essential electrical characteristics of cells, providing a deep understanding of the electrostatic changes in cancer cells compared to their normal counterparts. In particular, we provide an overview of intracellular and extracellular pH modifications, differences in ionic concentrations in the cytoplasm, transmembrane potential variations, and changes within mitochondria. New therapies targeting or exploiting the electrical properties of cells are developed and tested every year, such as pH-dependent carriers and tumour-treating fields. A brief section regarding the state-of-the-art of these therapies can be found at the end of this review. Finally, we highlight how these alterations integrate and potentially yield indications of cells' malignancy or metastatic index.

Role of SERCA3 in the Prognosis and Immune Function in Pan-Cancer

The sarcoendoplasmic reticulum calcium adenosine triphosphatase (ATPase) 3 (SERCA3), a member of the SERCA protein family, is located at the endoplasmic reticulum. Its main function is to pump Ca2+ into the endoplasmic reticulum and is involved in maintaining intracellular calcium homeostasis and signal transduction, which are very important factors impacting cancer development and progression. However, the specific role of SERCA3 in cancer remains unclear. Our study, for the first time, comprehensively analyzed the SERCA3 expression profile in multiple cancers and its prognostic value in different cancers using bioinformatics. Furthermore, TCGA database was applied to evaluate the certain correlation of SERCA3 expression with immune modulator genes, immune checkpoints, immune cell infiltration, TMB, and MSI. The results revealed that in many cancers, SERCA3 expression was markedly decreased, which was related to poor prognosis. Additionally, we noticed that SERCA3 expression was correlated with TNM classification and WHO cancer stages in some cancer types. The Pearson correlation analysis showed that SERCA3 expression was closely associated with chemokines, chemokine receptors, MHC, immune activation genes, and immunosuppressive genes. In most cancer types, SERCA3 expression was also associated with immune checkpoints, including PDCD1 and CTLA-4. Further analysis suggested that SERCA3 was significantly correlated with CD8+ T cells, and regulatory T cells. Additionally, pan-cancer analysis confirmed that SERCA3 expression was related to TMB and MSI. In conclusion, these results offer a new insight into the functions and effects of SERCA3 in pan-cancer, and further provide some basis for considering SERCA3 as a potential cancer treatment target and biomarker.

Blockage of Orai1-Nucleolin interaction meditated calcium influx attenuates breast cancer cells growth

As an important second messenger, calcium (Ca2+) regulates a wide variety of physiological processes. Disturbance of intracellular calcium homeostasis implicated in the occurrence of multiple types of diseases. Orai1 is the major player in mediating store-operated calcium entry (SOCE) and regulates calcium homeostasis in non-excitable cells. Over-expression and activation of Orai1 have been reported in breast cancer. However, its molecular mechanisms are still not very clear. Here, we demonstrated that Nucleolin (NCL) was a novel interacting partner of Orai1. NCL is a multifunctional nucleocytoplasmic protein and is upregulated in human breast tumors. The binding of C-termini of NCL (NCL-CT) to N-termini of Orai1 (Orai1-NT) is critical for mediating calcium influx and proliferation of breast cancer cells. Blocking the NCL-Orai1 interaction by synthesized Orai1 peptide can effectively reduce the intracellular calcium influx and suppress the proliferation of breast cancer cells in vitro and in vivo. Our findings reveal a novel activation mechanism of Orai1 via direct interaction with NCL, which may lead to calcium homeostasis imbalance and promote the proliferation of breast cancer cells. Blocking NCL-Orai1 interaction might be an effective treatment of breast cancer.

AFExNet: An Adversarial Autoencoder for Differentiating Breast Cancer Sub-Types and Extracting Biologically Relevant Genes

Technological advancements in high-throughput genomics enable the generation of complex and large data sets that can be used for classification, clustering, and bio-marker identification. Modern deep learning algorithms provide us with the opportunity of finding most significant features in such huge dataset to characterize diseases (e.g., cancer) and their sub-types. Thus, developing such deep learning method, which can successfully extract meaningful features from various breast cancer sub-types, is of current research interest. In this paper, we develop dual stage (unsupervised pre-training and supervised fine-tuning) neural network architecture termed AFExNet based on adversarial auto-encoder (AAE) to extract features from high dimensional genetic data. We evaluated the performance of our model through twelve different supervised classifiers to verify the usefulness of the new features using public RNA-Seq dataset of breast cancer. AFExNet provides consistent results in all performance metrics across twelve different classifiers which makes our model classifier independent. We also develop a method named 'TopGene' to find highly weighted genes from the latent space which could be useful for finding cancer bio-markers. Put together, AFExNet has great potential for biological data to accurately and effectively extract features. Our work is fully reproducible and source code can be downloaded from Github: https://github.com/NeuroSyd/breast-cancer-sub-types.

Aberrant calcium signalling downstream of mutations in TP53 and the PI3K/AKT pathway genes promotes disease progression and therapy resistance in triple negative breast cancer

Triple-negative breast cancer (TNBC) is characterized as an aggressive form of breast cancer (BC) associated with poor patient outcomes. For the majority of patients, there is a lack of approved targeted therapies. Therefore, chemotherapy remains a key treatment option for these patients, but significant issues around acquired resistance limit its efficacy. Thus, TNBC has an unmet need for new targeted personalized medicine approaches. Calcium (Ca²⁺) is a ubiquitous second messenger that is known to control a range of key cellular processes by mediating signalling transduction and gene transcription. Changes in Ca²⁺ through altered calcium channel expression or activity are known to promote tumorigenesis and treatment resistance in a range of cancers including BC. Emerging evidence shows that this is mediated by Ca²⁺ modulation, supporting the function of tumour suppressor genes (TSGs) and oncogenes. This review provides insight into the underlying alterations in calcium signalling and how it plays a key role in promoting disease progression and therapy resistance in TNBC which harbours mutations in tumour protein p53 (TP53) and the PI3K/AKT 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.

MicroRNA-129-1-3p Represses the Progression of Triple-Negative Breast Cancer by Targeting the GRIN2D Gene

The aberrant expression of miRNA is strongly linked to numerous stages of triple-negative breast cancer (TNBC) progression, and it plays an indispensable role in the process from tumor onset and progress to invasion and metastasis. In this study, we first transfected miR-129-1-3p mimics and inhibitor into MDA-MB-231 TNBC cells, respectively. Then, we assessed the pathological role of miR-129-1-3p in MDA-MB-231 cells. The results showed that miR-129-1-3p were successfully inserted into MDA-MB-231 cells. Besides, miR-129-1-3p could distinctively repress the growth, migration along with infiltration of MDA-MB-231 cells, which might be related to the inhibition of GRIN2D expression. Our results indicate that miR-129-1-3p was illustrated to serve as a tumor repressor via targeting GRIN2D in TNBC cells and highlight that the restoration of miR-129-1-3p might be a new treatment target for TNBC.

Calcium Signalling in Breast Cancer Associated Bone Pain

Calcium (Ca²⁺) is involved as a signalling mediator in a broad variety of physiological processes. Some of the fastest responses in human body like neuronal action potential firing, to the slowest gene transcriptional regulation processes are controlled by pathways involving calcium signalling. Under pathological conditions these mechanisms are also involved in tumoral cells reprogramming, resulting in the altered expression of genes associated with cell proliferation, metastatisation and homing to the secondary metastatic site. On the other hand, calcium exerts a central function in nociception, from cues sensing in distal neurons, to signal modulation and interpretation in the central nervous system leading, in pathological conditions, to hyperalgesia, allodynia and pain chronicization. It is well known the relationship between cancer and pain when tumoral metastatic cells settle in the bones, especially in late breast cancer stage, where they alter the bone micro-environment leading to bone lesions and resulting in pain refractory to the conventional analgesic therapies. The purpose of this review is to address the Ca²⁺ signalling mechanisms involved in cancer cell metastatisation as well as the function of the same signalling tools in pain regulation and transmission. Finally, the possible interactions between these two cells types cohabiting the same Ca²⁺ rich environment will be further explored attempting to highlight new possible therapeutical targets.

Pan-Cancer Analysis Reveals Genomic and Clinical Characteristics of TRPV Channel-Related Genes

Background

Transient Receptor Potential channels (TRPs), a class of ion channels, were first described two decades ago. Many TRP family members are major participants in nociception and integration of heat and pain signals. Recent studies have revealed that subfamilies of this channel, such as members of transient receptor potential vanilloid (TRPV) channels, play important roles in breast, ovarian, prostate, and pancreatic cancers.

Methods

We performed a comprehensive analysis of TRPVs in 9125 tumor samples of 33 cancer types using multi-omics data extracted from The Cancer Genome Atlas (TCGA). We identified differences in mRNA expression in a pan-cancer analysis, and the genomic characteristics of single nucleotide variations, copy number variations, methylation features, and miRNA–mRNA interactions using data from TCGA. Finally, we evaluated the sensitivity and resistance to drugs targeting TRPV channel-related genes using the Cancer Therapeutics Response Portal (CTRP) and the Genomics of Drug Sensitivity in Cancer (GDSC) database. Finally, we validated the drug sensitive data and the importance of TRPV6 in two cancer cell lines using q-PCR assay, CCK8 assay, EdU assay and scratch assay.

Results

Extensive genetic alterations in TRPV channel-related genes and differences in gene expression were associated with the activity of cancer marker-related pathways. TRPV channel-related genes can be used as prognostic biomarkers. Several potential drugs, such as lapatinib, that may target TRPV channel-related genes were identified by mining the genomics of drug sensitivity.

Conclusion

This study revealed the genomic changes and clinical characteristics of TRPV channel-related regulatory factors in 33 types of tumors. This analysis may help uncover the TRPV channel-related genes associated with tumorigenesis. We also proposed novel strategies for tumor treatment.

Estrogen Receptors-Mediated Apoptosis in Hormone-Dependent Cancers

It is known that estrogen stimulates growth and inhibits apoptosis through estrogen receptor(ER)-mediated mechanisms in many cancer cell types. Interestingly, there is strong evidence that estrogens can also induce apoptosis, activating different ER isoforms in cancer cells. It has been observed that E2/ERα complex activates multiple pathways involved in both cell cycle progression and apoptotic cascade prevention, while E2/ERβ complex in many cases directs the cells to apoptosis. However, the exact mechanism of estrogen-induced tumor regression is not completely known. Nevertheless, ERs expression levels of specific splice variants and their cellular localization differentially affect outcome of estrogen-dependent tumors. The goal of this review is to provide a general overview of current knowledge on ERs-mediated apoptosis that occurs in main hormone dependent-cancers. Understanding the molecular mechanisms underlying the induction of ER-mediated cell death will be useful for the development of specific ligands capable of triggering apoptosis to counteract estrogen-dependent tumor growth.

Effects of Propofol Versus Sevoflurane on Postoperative Breast Cancer Prognosis: A Narrative Review

Perioperative interventions produce substantial biologic perturbations which are associated with the risk of recurrence after cancer surgery. The changes of tumor microenvironment caused by anesthetic drugs received increasing attention. Till now, it’s still unclear whether or not anesthetic drugs may exert positive or negative impact on cancer outcomes after surgery. Breast cancer is the most common tumor and the leading cause of cancer deaths in women. Propofol and sevoflurane are respectively the most commonly used intravenous and inhaled anesthetics. Debates regarding which of the two most commonly used anesthetics may relatively contribute to the recurrence and metastasis vulnerability of breast cancer postoperatively remain. This review aimed to provide a comprehensive view about the effect of propofol versus sevoflurane on the prognosis of breast cancer obtained from pre-clinical studies and clinical studies. Laboratory and animal studies have demonstrated that sevoflurane may enhance the recurrence and metastasis of breast cancer, while propofol is more likely to reduce the activity of breast cancer cells by attenuating the suppression of the immune system, promoting tumor cells apoptosis, and through other direct anti-tumor effects. However, retrospective clinical studies have shown contradictory results about the effects of propofol and sevoflurane on long-term survival in breast cancer patients. Furthermore, recent prospective studies did not identify significant differences between propofol and sevoflurane in breast cancer metastasis and recurrence. Therefore, more preclinical studies and randomized controlled studies are needed to guide the choice of anesthetics for breast cancer patients.

TRPM7 Ion Channel: Oncogenic Roles and Therapeutic Potential in Breast Cancer

Simple Summary

Breast cancer is the most frequently diagnosed malignant tumor and the second leading cause of cancer death in women worldwide. The risk of developing breast cancer is 12.8%, i.e., 1 in 8 people, and a woman’s risk of dying is approximately 1 in 39. Calcium signals play an important role in various cancers and transport calcium ions may have altered expression in breast cancer, such as the TRPM7 calcium permeant ion channel, where overexpression may be associated with a poor prognosis. This review focuses on the TRPM7 channel, and the oncogenic roles studied so far in breast cancer. The TRPM7 ion channel is suggested as a potential and prospective target in the diagnosis and treatment of breast cancer.

Abstract

The transient receptor potential melastatin-subfamily member 7 (TRPM7) is a divalent cations permeant channel but also has intrinsic serine/threonine kinase activity. It is ubiquitously expressed in normal tissues and studies have indicated that it participates in important physiological and pharmacological processes through its channel-kinase activity, such as calcium/magnesium homeostasis, phosphorylation of proteins involved in embryogenesis or the cellular process. Accumulating evidence has shown that TRPM7 is overexpressed in human pathologies including breast cancer. Breast cancer is the second leading cause of cancer death in women with an incidence rate increase of around 0.5% per year since 2004. The overexpression of TRPM7 may be associated with a poor prognosis in breast cancer patients, so more efforts are needed to research a new therapeutic target. TRPM7 regulates the levels of Ca²⁺, which can alter the signaling pathways involved in survival, cell cycle progression, proliferation, growth, migration, invasion, epithelial-mesenchymal transition and thus determines cell behavior, promoting tumor development. This work provides a complete overview of the TRPM7 ion channel and its main involvements in breast cancer. Special consideration is given to the modulation of the channel as a potential target in breast cancer treatment by inhibition of proliferation, migration and invasion. Taken together, these data suggest the potential exploitation of TRPM7 channel-kinase as a therapeutic target and a diagnostic biomarker.

Expression and associated epigenetic mechanisms of the Ca2+-signaling genes in breast cancer subtypes and epithelial-to-mesenchymal transition

Breast cancer-associated deaths are related mainly to specific molecular subtypes and the presence of metastasis. The Epithelial-to-Mesenchymal Transition (EMT) and Ca²⁺ signaling pathways are involved in breast cancer metastasis, and they are regulated in part by epigenetic mechanisms. Moreover, activation of EMT modulates Ca²⁺ concentration and in turn, Ca²⁺ signaling regulates the expression of EMT markers. Also, activation of Ca²⁺ signaling genes with epigenetic inhibitors reverts the EMT. Thus, Ca²⁺ signaling might have an important role in breast cancer metastasis and EMT, particularly through the epigenetic regulation of genes involved in its signaling. However, little is known due to that an estimate of 1670 genes participate in the Ca²⁺ signaling and only a few genes have been studied. Here, we aimed to explore the expression of all genes involved in Ca²⁺ signaling in all breast cancer subtypes and EMT, and whether modulation of epigenetic mechanisms is related to their expression. Several genes of the Ca²⁺ signaling are altered in all breast cancer subtypes, being the cadherins and voltage channels the most frequent altered genes. Also, DNA methylation and histone posttranslational modifications showed a good correlation with their altered expression. The expression of the cadherins and voltage channels is also modulated during breast EMT, and ATAC-seq results suggest that chromatin rearrangement at their promoter is involved. In conclusion, the expression of the genes involved in Ca²⁺ signaling is altered in all breast cancer subtypes and during EMT, and epigenetic mechanisms are an attractive target to regulate their expression.

Image-Guided TME-Improving Nano-Platform for Ca2+ Signal Disturbance and Enhanced Tumor PDT

Dysfunction of the calcium balancing system and disruption of calcium distribution can induce abnormal intracellular calcium overload, further causing serious damage and even cell death, which provides a potential therapeutic approach for tumor treatment. Herein, a nano-platform, which includes UCNPs-Ce6@RuR@mSiO₂ @PL-HA NPs (UCRSPH) and SA-CaO₂ nanoparticles, is prepared for improving the tumor micro-environment (TME), Ca²⁺ signal disturbance as well as enhanced photodynamic tumor therapy (PDT). UCRSPH combined with SA-CaO₂ can alter TME and relieve hypoxia of the tumor to realize self-reinforcing PDT under near-IR irradiation (980 nm). The ruthenium red (RuR) in the UCRSPH NPs can be released to the cytoplasm after endocytosis of the nanoparticles, target Ca²⁺ channel proteins on the endoplasmic reticulum and mitochondria, sarcoplasmic reticulum Ca²⁺ -ATPase (SERCA), and mitochondrial calcium uniporter (MCU). The combined participation of nanoparticles and RuR promotes Ca²⁺ imbalance and cytoplasmic calcium overload with the assistance of CaO₂ , and provides tumor cells higher sensitivity to PDT. Furthermore, the nano-platform also provides fluorescence imaging and calcification computed tomography imaging for in vivo treatment guidance. In conclusion, this image-guided nano-platform show potential for highly specific, efficient combined therapy against tumor cells with minimal side-effects to normal cells by integrating TME improvement, self-reinforcing PDT, and Ca²⁺ signal disturbance.

Mangifera indica (Mango): A Promising Medicinal Plant for Breast Cancer Therapy and Understanding Its Potential Mechanisms of Action

Globally, breast cancer is the most common cancer type and is one of the most significant causes of deaths in women. To date, multiple clinical interventions have been applied, including surgical resection, radiotherapy, endocrine therapy, targeted therapy and chemotherapy. However, 1) the lack of therapeutic options for metastatic breast cancer, 2) resistance to drug therapy and 3) the lack of more selective therapy for triple-negative breast cancer are some of the major challenges in tackling breast cancer. Given the safe nature of natural products, numerous studies have focused on their anti-cancer potentials. Mangifera indica, commonly known as mango, represents one of the most extensively investigated natural sources. In this review, we provide a comprehensive overview of M. indica extracts (bark, kernel, leaves, peel and pulp) and phytochemicals (mangiferin, norathyriol, gallotannins, gallic acid, pyrogallol, methyl gallate and quercetin) reported for in vitro and in vivo anti-breast cancer activities and their underlying mechanisms based on relevant literature from several scientific databases, including PubMed, Scopus and Google Scholar till date. Overall, the in vitro findings suggest that M. indica extracts and/or phytochemicals inhibit breast cancer cell growth, proliferation, migration and invasion as well as trigger apoptosis and cell cycle arrest. In vivo results demonstrated that there was a reduction in breast tumor xenograft growth. Several potential mechanisms underlying the anti-breast cancer activities have been reported, which include modulation of oxidative status, receptors, signalling pathways, miRNA expression, enzymes and cell cycle regulators. To further explore this medicinal plant against breast cancer, future research directions are addressed. The outcomes of the review revealed that M. indica extracts and their phytochemicals may have potential benefits in the management of breast cancer in women. However, to validate its utility in the creation of innovative and potent therapeutic agents to treat breast cancer, more dedicated research, especially clinical studies are needed to explore the anti-breast cancer potentials of M. indica extracts and their phytochemicals.

Repurposing calcium channel blockers: may be sensible combination with erlotinib for non-small cell lung cancer

Erlotinib is a tyrosine kinase inhibitor that inhibits epidermal growth factor receptor. It is being used for metastatic non-small cell lung cancer patients (NSCLC). Repurposing noncancer drugs for cancer treatment is a current issue and it has many advantages. We planned to reveal the effects of noncancer drugs [calcium channel blockers (CCBs) and others] on erlotinib. We scanned the files of NSCLC patients retrospectively who were applied to Karadeniz Technical University between January 2013 and April 2019 and used erlotinib. There were 63 patients, 9 of them were taking CCB simultaneously for arterial hypertension. We analyzed some parameters of these patients and their effects on overall survival (OS) and progression-free survival (PFS). A χ2 or Fisher's exact test, Kaplan-Meier and Cox regressions were used in the statistical analysis. 12-month OS rates of CCB user and nonuser were 78.3 and 39.7%, respectively, [odds ratio (OR),0.14; 95% confidence interval (CI), 0.27-0.75; P = 0.023]. 24-month PFS rates of CCB user and nonuser were 44.4 and 8.3%, respectively (OR,0.11; 95% CI, 0.02-0.60; P = 0.016). There was 12-month OS and 24-month PFS advantage with simultaneously taking CCBs and erlotinib, they have an additive effect for NSCLC. This study will be inspiring future prospective studies.

Lockdown of mitochondrial Ca2+ extrusion and subsequent resveratrol treatment kill HeLa cells by Ca2+ overload

Anticancer effect of resveratrol and the role of sodium/lithium/calcium exchanger in context with calcium ions are studied in human cervical cancer cell line. This therapeutic approach using siNCLX mediated gene silencing and drug therapy with resveratrol indicates the disruption of calcium homeostasis, increase in caspase (-3, 8, 9) mRNA expressions and DNA damage leading to apoptotic cell death. Monitoring the intracellular Ca²⁺ changes using fluo-4AM indicates highest rise in [Ca²⁺] level in sodium/lithium/calcium exchanger silenced group with five different stages, that is distinguishable based on the fluorescence intensity. In resveratrol treated and siNCLX + resveratrol treated groups no such cell staging differences were observed, despite uniform Ca²⁺ rise followed by decrease in the intensity. Integrating RNAi gene silencing of sodium/lithium/calcium exchanger with resveratrol can form the most interesting, efficient and promising therapeutic strategy in the treatment of cancer.

MCUR1 is a prognostic biomarker for ovarian cancer patients

PURPOSE

To propose MCUR1 gene as a potential biomarker for ovarian cancer prognosis.

METHODS

The ovarian cancer patient specimen from TCGA database were analyzed using survival analysis. The immune cell infiltration ratio and checkpoints had also been investigated for different expression group of MCUR1. The function of MCUR1 as a ovarian cancer prognosis biomarker was verified in clinic.

RESULTS

The low expression of MCUR1 was associated with the poor prognosis of ovarian cancer patients. The expressions of majority of immune cells and 6 checkpoints in low expression group of MCUR1 were significantly lower than that in high expression group of MCUR1 (P< 0.05). The MCUR1 could be utilized as a prognostic biomarker for ovarian cancer patients in clinic.

CONCLUSION

This study has proposed a potential prognostic biomarker for ovarian cancer patients, which offers a beneficial reference for future ovarian cancer administration.

Calcium channel TRPV6 promotes breast cancer metastasis by NFATC2IP

Calcium channel TRPV6 upregulation is associated with poor prognosis of breast cancer by promoting invasion and metastasis, and TRPV6 is a potential target for breast cancer therapy. However, the mechanism by which TRPV6 promotes breast metastasis remains unclear. Here, we report that TRPV6 expression is upregulated in metastatic breast cancers and that TRPV6 overexpression or upregulation accelerates primary breast cancer cell migration. In contrast, TRPV6 suppression decreases cell migration. Mechanistically, TRPV6 activates NFATC2 by increasing NFATC2IP phosphorylation at Ser204, and CDK5 is a candidate kinase that may perform this phosphorylation. Consequently, activated NFATC2 increases breast cancer metastasis by upregulating ADAMTS6 expression. These observations suggest that TRPV6 increases NFATC2 transcriptional activity by increasing NFATC2IP phosphorylation, which consequently upregulates ADAMTS6 expression to promote breast cancer metastasis.

Store-Independent Calcium Entry and Related Signaling Pathways in Breast Cancer

Known as a key effector in breast cancer (BC) progression, calcium (Ca²⁺) is tightly regulated to maintain the desired concentration to fine-tune cell functions. Ca²⁺ channels are the main actors among Ca²⁺ transporters that control the intracellular Ca²⁺ concentration in cells. It is well known that the basal Ca²⁺ concentration is regulated by both store-dependent and independent Ca²⁺ channels in BC development and progression. However, most of the literature has reported the role of store-dependent Ca²⁺ entry, and only a few studies are focusing on store-independent Ca²⁺ entry (SICE). In this review, we aim to summarize all findings on SICE in the BC progression field.

TRP Channels Interactome as a Novel Therapeutic Target in Breast Cancer

Breast cancer is one of the most frequent cancer types worldwide and the first cause of cancer-related deaths in women. Although significant therapeutic advances have been achieved with drugs such as tamoxifen and trastuzumab, breast cancer still caused 627,000 deaths in 2018. Since cancer is a multifactorial disease, it has become necessary to develop new molecular therapies that can target several relevant cellular processes at once. Ion channels are versatile regulators of several physiological- and pathophysiological-related mechanisms, including cancer-relevant processes such as tumor progression, apoptosis inhibition, proliferation, migration, invasion, and chemoresistance. Ion channels are the main regulators of cellular functions, conducting ions selectively through a pore-forming structure located in the plasma membrane, protein–protein interactions one of their main regulatory mechanisms. Among the different ion channel families, the Transient Receptor Potential (TRP) family stands out in the context of breast cancer since several members have been proposed as prognostic markers in this pathology. However, only a few approaches exist to block their specific activity during tumoral progress. In this article, we describe several TRP channels that have been involved in breast cancer progress with a particular focus on their binding partners that have also been described as drivers of breast cancer progression. Here, we propose disrupting these interactions as attractive and potential new therapeutic targets for treating this neoplastic disease.

The Orai1-AC8 Interplay: How Breast Cancer Cells Escape from Orai1 Channel Inactivation

The interplay between the Ca2+-sensitive adenylyl cyclase 8 (AC8) and Orai1 channels plays an important role both in the activation of the cAMP/PKA signaling and the modulation of Orai1-dependent Ca2+ signals. AC8 interacts with a N-terminal region that is exclusive to the Orai1 long variant, Orai1α. The interaction between both proteins allows the Ca2+ that enters the cell through Orai1α to activate the generation of cAMP by AC8. Subsequent PKA activation results in Orai1α inactivation by phosphorylation at serine-34, thus shaping Orai1-mediated cellular functions. In breast cancer cells, AC8 plays a relevant role supporting a variety of cancer hallmarks, including proliferation and migration. Breast cancer cells overexpress AC8, which shifts the AC8-Orai1 stoichiometry in favor of the former and leads to the impairment of PKA-dependent Orai1α inactivation. This mechanism contributes to the enhanced SOCE observed in triple-negative breast cancer cells. This review summarizes the functional interaction between AC8 and Orai1α in normal and breast cancer cells and its relevance for different cancer features.

Resveratrol sensitizes A549 cells to irradiation damage via suppression of store-operated calcium entry with Orai1 and STIM1 downregulation

Resveratrol is a natural polyphenol with multiple positive biofunctions and was found to have potential as a radiosensitizer with an intricate molecular mechanism. Store-operated calcium entry (SOCE) is a novel intracellular calcium regulatory pattern that is mainly mediated by iron channels, such as by the stromal interaction molecule (STIM) and calcium release-activated calcium channel protein (Orai) families. SOCE was recently reported to be suppressed via the downregulation of STIM or Orai families for the promotion of tumor cell death induced by resveratrol. In the present study, resveratrol combined with irradiation treatment were found to induce more evident cell damage compared with irradiation treatment alone, as shown with Cell Counting Kit-8 assay and mitochondrial membrane potential detection with rhodamine 123. Additionally, resveratrol combined with irradiation treatment decreased the expression of STIM1 and Orai1, while it had no effects on STIM2, Orai2 and Orai3. Moreover, resveratrol combined with irradiation treatment lead to alleviated thapsigargin-induced SOCE. In addition, overexpression of STIM1 and Orai1 reversed resveratrol-induced SOCE inhibition and reduced death in A549 cells under irradiation. In summary, the present results revealed that resveratrol can significantly enhance the effect of irradiation damage on lung adenocarcinoma A549 cells, and this effect may be mediated by suppression of SOCE with reduced expression of both STIM1 and Orai1.

Ca2+ Signaling as the Untact Mode during Signaling in Metastatic Breast Cancer

Simple Summary

Intracellular Ca²⁺ signaling is a critical factor in breast cancer metastasis. In the proliferation stage, increases in intracellular Ca²⁺ concentration through voltage-dependent Ca²⁺ channels, P₂Y₂ channels, transient receptor potential (TRP) channels, store-operated Ca²⁺ channels (SOCCs), and IP₃ receptors and a decrease in intracellular Ca²⁺ concentration through plasma membrane Ca²⁺ ATPases and secretory pathway Ca²⁺ ATPases (SPCA) activate breast cancer cell proliferation. TRPM7, SOCC, inositol trisphosphate receptor (IP₃R), ryanodine receptor (RyR), and sarco-/endo-plasmic reticulum Ca²⁺-ATPase (SERCA) increase the expression of epithelial-to-mesenchymal transition (EMT)-related proteins; meanwhile, SPCA and the Na⁺/Ca²⁺ exchanger (NCX) control the activation of EMT-related proteins. Increased Ca²⁺ through TRPC1, TRPM7/8, P₂X₇, and SOCC enhances breast cancer cell migration. The stromal interaction molecule (STIM)-Orai complex, P₂X₇, and Ca²⁺ sensing receptors are involved in invadopodia. Various pharmacological agents for Ca²⁺ channels have been proposed against breast cancer and have provided potential strategies for treating metastatic processes.

Abstract

Metastatic features of breast cancer in the brain are considered a common pathology in female patients with late-stage breast cancer. Ca²⁺ signaling and the overexpression pattern of Ca²⁺ channels have been regarded as oncogenic markers of breast cancer. In other words, breast tumor development can be mediated by inhibiting Ca²⁺ channels. Although the therapeutic potential of inhibiting Ca²⁺ channels against breast cancer has been demonstrated, the relationship between breast cancer metastasis and Ca²⁺ channels is not yet understood. Thus, we focused on the metastatic features of breast cancer and summarized the basic mechanisms of Ca²⁺-related proteins and channels during the stages of metastatic breast cancer by evaluating Ca²⁺ signaling. In particular, we highlighted the metastasis of breast tumors to the brain. Thus, modulating Ca²⁺ channels with Ca²⁺ channel inhibitors and combined applications will advance treatment strategies for breast cancer metastasis to the brain.

Relevance of Membrane Contact Sites in Cancer Progression

Membrane contact sites (MCS) are typically defined as areas of proximity between heterologous or homologous membranes characterized by specific proteins. The study of MCS is considered as an emergent field that shows how crucial organelle interactions are in cell physiology. MCS regulate a myriad of physiological processes such as apoptosis, calcium, and lipid signaling, just to name a few. The membranal interactions between the endoplasmic reticulum (ER)–mitochondria, the ER–plasma membrane, and the vesicular traffic have received special attention in recent years, particularly in cancer research, in which it has been proposed that MCS regulate tumor metabolism and fate, contributing to their progression. However, as the therapeutic or diagnostic potential of MCS has not been fully revisited, in this review, we provide recent information on MCS relevance on calcium and lipid signaling in cancer cells and on its role in tumor progression. We also describe some proteins associated with MCS, like CERT, STIM1, VDAC, and Orai, that impact on cancer progression and that could be a possible diagnostic marker. Overall, these information might contribute to the understanding of the complex biology of cancer cells.

Orai channels: key players in Ca2+ homeostasis

Maintaining a precise calcium (Ca²⁺) balance is vital for cellular survival. The most prominent pathway to shuttle Ca²⁺ into cells is the Ca²⁺ release activated Ca²⁺ (CRAC) channel. Orai proteins are indispensable players in this central mechanism of Ca²⁺ entry. This short review traces the latest articles published in the field of CRAC channel signalling with a focus on the structure of the pore-forming Orai proteins, the propagation of the binding signal from STIM1 through the channel to the central pore and their role in human health and disease.

Calcium signaling: breast cancer's approach to manipulation of cellular circuitry

Calcium is a versatile element that participates in cell signaling for a wide range of cell processes such as death, cell cycle, division, migration, invasion, metabolism, differentiation, autophagy, transcription, and others. Specificity of calcium in each of these processes is achieved through modulation of intracellular calcium concentrations by changing the characteristics (amplitude/frequency modulation) or location (spatial modulation) of the signal. Breast cancer utilizes calcium signaling as an advantage for survival and progression. This review integrates evidence showing that increases in expression of calcium channels, GPCRs, pumps, effectors, and enzymes, as well as resulting intracellular calcium signals, lead to high calcium and/or an elevated calcium- mobilizing capacity necessary for malignant functions such as migratory, invasive, proliferative, tumorigenic, or metastatic capacities.

Calcium Metabolism and Breast Cancer: Echoes of Lactation?

Lactation requires a series of adaptations in maternal calcium and bone metabolism to ensure a steady supply of calcium to the lactating mammary gland. The alterations in systemic metabolism are accompanied by alterations in the expression of calcium receptors, channels, binding proteins, pumps and transporters in mammary epithelial cells to increase the uptake of calcium from the extracellular fluid and to transport it into milk. Intracellular calcium regulates signaling pathways that mediate changes in cell proliferation, differentiation and death and many of the molecules involved in supporting and coordinating calcium secretion into milk are re-expressed and redeployed to support malignant behavior in breast cancer cells. In this article, we review adaptations of systemic calcium homeostasis during lactation, as well as the mechanisms of milk calcium transport. We then discuss how reactivation of these pathways contributes to the pathophysiology of breast cancer.

Towards an Integral Therapeutic Protocol for Breast Cancer Based upon the New H+-Centered Anticancer Paradigm of the Late Post-Warburg Era

A brand new approach to the understanding of breast cancer (BC) is urgently needed. In this contribution, the etiology, pathogenesis, and treatment of this disease is approached from the new pH-centric anticancer paradigm. Only this unitarian perspective, based upon the hydrogen ion (H+) dynamics of cancer, allows for the understanding and integration of the many dualisms, confusions, and paradoxes of the disease. The new H+-related, wide-ranging model can embrace, from a unique perspective, the many aspects of the disease and, at the same time, therapeutically interfere with most, if not all, of the hallmarks of cancer known to date. The pH-related armamentarium available for the treatment of BC reviewed here may be beneficial for all types and stages of the disease. In this vein, we have attempted a megasynthesis of traditional and new knowledge in the different areas of breast cancer research and treatment based upon the wide-ranging approach afforded by the hydrogen ion dynamics of cancer. The concerted utilization of the pH-related drugs that are available nowadays for the treatment of breast cancer is advanced.

Sevoflurane modulates breast cancer cell survival via modulation of intracellular calcium homeostasis

Background

Some retrospective and in vitro studies suggest that general anesthetics influence breast cancer recurrence and metastasis. We compared the effects of general anesthetics sevoflurane versus propofol on breast cancer cell survival, proliferation and invasion in vitro. The investigation focused on effects in intracellular Ca²⁺ homeostasis as a mechanism for general anesthetic-mediated effects on breast cancer cell survival and metastasis.

Methods

Estrogen receptor-positive (MCF7) and estrogen receptor-negative (MDA-MB-436) human breast cancer cell lines along with normal breast tissue (MCF10A) were used. Cells were exposed to sevoflurane or propofol at clinically relevant and extreme doses and durations for dose- and time-dependence studies. Cell survival, proliferation and migration following anesthetic exposure were assessed. Intracellular and extracellular Ca²⁺ concentrations were modulated using Ca²⁺ chelation and a TRPV1 Ca²⁺ channel antagonist to examine the role of Ca²⁺ in mediating anesthetic effects.

Results

Sevoflurane affected breast cancer cell survival in dose-, time- and cell type-dependent manners. Sevoflurane, but not propofol, at equipotent and clinically relevant doses (2% vs. 2 μM) for 6 h significantly promoted breast cell survival in all three types of cells. Paradoxically, extreme exposure to sevoflurane (4%, 24 h) decreased survival in all three cell lines. Chelation of cytosolic Ca²⁺ dramatically decreased cell survival in both breast cancer lines but not control cells. Inhibition of TRPV1 receptors significantly reduced cell survival in all cell types, an effect that was partially reversed by equipotent sevoflurane but not propofol. Six-hour exposure to sevoflurane or propofol did not affect cell proliferation, metastasis or TRPV1 protein expression in any type of cell.

Conclusion

Sevoflurane, but not propofol, at clinically relevant concentrations and durations, increased survival of breast cancer cells in vitro but had no effect on cell proliferation, migration or TRPV1 expression. Breast cancer cells require higher cytoplasmic Ca²⁺ levels for survival than normal breast tissue. Sevoflurane affects breast cancer cell survival via modulation of intracellular Ca²⁺ homeostasis.

Triple-Negative Breast Cancer Cells Exhibit Differential Sensitivity to Cardenolides from Calotropis gigantea

Triple-negative breast cancers (TNBC) are aggressive and heterogeneous cancers that lack targeted therapies. We implemented a screening program to identify new leads for subgroups of TNBC using diverse cell lines with different molecular drivers. Through this program, we identified an extract from Calotropis gigantea that caused selective cytotoxicity in BT-549 cells as compared to four other TNBC cell lines. Bioassay-guided fractionation of the BT-549 selective extract yielded nine cardenolides responsible for the selective activity. These included eight known cardenolides and a new cardenolide glycoside. Structure-activity relationships among the cardenolides demonstrated a correlation between their relative potencies toward BT-549 cells and Na+/K+ ATPase inhibition. Calotropin, the compound with the highest degree of selectivity for BT-549 cells, increased intracellular Ca2+ in sensitive cells to a greater extent than in the resistant MDA-MB-231 cells. Further studies identified a second TNBC cell line, Hs578T, that is also highly sensitive to the cardenolides, and mechanistic studies were conducted to identify commonalities among the sensitive cell lines. Experiments showed that both cardenolide-sensitive cell lines expressed higher mRNA levels of the Na+/Ca2+ exchanger NCX1 than resistant TNBC cells. This suggests that NCX1 could be a biomarker to identify TNBC patients that might benefit from the clinical administration of a cardiac glycoside for anticancer indications.

Metal ions and the extracellular matrix in tumor migration

In this review, we explore the roles of divalent metal ions in structure and function within the extracellular matrix (ECM), specifically, their interaction with glycosaminoglycans (GAGs) during tumor progression. Metals and GAGs have been individually associated with physiological and pathological processes, however, their combined activities in regulating cell behavior and ECM remodeling have not been fully explored to date. During tumor progression, divalent metals and GAGs participate in central processes, such as cell migration and angiogenesis, either by modulating cell surface molecules, as well as soluble signaling factors. In addition, studies on metals and polysaccharides interactions have been of great value, as they provide structural information that can be correlated with function. Finally, we believe that understanding how metals are regulated in physiological and pathological conditions is paramount for the development of new treatment strategies, as well as diagnostic and exploratory tools.

Calcium Homeostasis: A Potential Vicious Cycle of Bone Metastasis in Breast Cancers

Cancers have been considered as one of the most severe health problems in the world. Efforts to elucidate the cancer progression reveal the importance of bone metastasis for tumor malignancy, one of the leading causes for high mortality rate. Multiple cancers develop bone metastasis, from which breast cancers exhibit the highest rate and have been well-recognized. Numerous cells and environmental factors have been believed to synergistically facilitate bone metastasis in breast cancers, from which breast cancer cells, osteoclasts, osteoblasts, and their produced cytokines have been well-recognized to form a vicious cycle that aggravates tumor malignancy. Except the cytokines or chemokines, calcium ions are another element largely released from bones during bone metastasis that leads to hypercalcemia, however, have not been well-characterized yet in modulation of bone metastasis. Calcium ions act as a type of unique second messenger that exhibits omnipotent functions in numerous cells, including tumor cells, osteoclasts, and osteoblasts. Calcium ions cannot be produced in the cells and are dynamically fluxed among extracellular calcium pools, intracellular calcium storages and cytosolic calcium signals, namely calcium homeostasis, raising a possibility that calcium ions released from bone during bone metastasis would further enhance bone metastasis and aggravate tumor progression via the vicious cycle due to abnormal calcium homeostasis in breast cancer cells, osteoclasts and osteoblasts. TRPs, VGCCs, SOCE, and P2Xs are four major calcium channels/routes mediating extracellular calcium entry and affect calcium homeostasis. Here we will summarize the overall functions of these four calcium channels in breast cancer cells, osteoclasts and osteoblasts, providing evidence of calcium homeostasis as a vicious cycle in modulation of bone metastasis in breast cancers.

Transient receptor potential cation channel subfamily V and breast cancer

Transient receptor potential cation channel subfamily V (TRPV) channels play important roles in a variety of cellular processes. One example includes the sensory role of TRPV1 that is sensitive to elevated temperatures and acidic environments and is activated by the hot pepper component capsaicin. Another example is the importance of the highly Ca²⁺ selective channels TRPV5 and TRPV6 in Ca²⁺ absorption/reabsorption in the intestine and kidney. However, in some cases such as TRPV4 and TRPV6, breast cancer cells appear to overexpress TRPV channels. Moreover, TRPV mediated Ca²⁺ influx may contribute to enhanced breast cancer cell proliferation and other processes important in tumor progression such as angiogenesis. It appears that the overexpression of some TRPV channels in breast cancer and/or their involvement in breast cancer cell processes, processes important in the tumor microenvironment or pain may make some TRPV channels potential targets for breast cancer therapy. In this review, we provide an overview of TRPV expression in breast cancer subtypes, the roles of TRPV channels in various aspects of breast cancer progression and consider implications for future therapeutic approaches.