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

Hypercalcemia in Cancer: Causes, Effects, and Treatment Strategies

Calcium plays central roles in numerous biological processes, thereby, its levels in the blood are under strict control to maintain homeostatic balance and enable the proper functioning of living organisms. The regulatory mechanisms ensuring this balance can be affected by pathologies such as cancer, and as a result, hyper- or hypocalcemia can occur. These states, characterized by elevated or decreased calcium blood levels, respectively, have a significant effect on general homeostasis. This article focuses on a particular form of calcium metabolism disorder, which is hypercalcemia in neoplasms. It also constitutes a summary of the current knowledge regarding the diagnosis of hypercalcemia and its management. Hypercalcemia of malignancy is estimated to affect over 40% of cancer patients and can be associated with both solid and blood cancers. Elevated calcium levels can be an indicator of developing cancer. The main mechanism of hypercalcemia development in tumors appears to be excessive production of parathyroid hormone-related peptides. Among the known treatment methods, bisphosphonates, calcitonin, steroids, and denosumab should be mentioned, but ongoing research promotes progress in pharmacotherapy. Given the rising global cancer prevalence, the problem of hypercalcemia is of high importance and requires attention.

Bone Endosteal Mimics Regulates Breast Cancer Development and Phenotype

Bone is a frequent site for metastatic development in various cancer types, including breast cancer, with a grim prognosis due to the distinct bone environment. Despite considerable advances, our understanding of the underlying processes leading to bone metastasis progression remains elusive. Here, we applied a bioactive three-dimensional (3D) model capable of mimicking the endosteal bone microenvironment. MDA-MB-231 and MCF7 breast cancer cells were cultured on the scaffolds, and their behaviors and the effects of the biomaterial on the cells were examined over time. We demonstrated that close interactions between the cells and the biomaterial affect their proliferation rates and the expression of c-Myc, cyclin D, and KI67, leading to cell cycle arrest. Moreover, invasion assays revealed increased invasiveness within this microenvironment. Our findings suggest a dual role for endosteal mimicking signals, influencing cell fate and potentially acting as a double-edged sword, shuttling between cell cycle arrest and more active, aggressive states.

Prevalence of vitamin D deficiency and its association with cardiometabolic risk factors among healthcare workers in the Eastern Cape province, South Africa; cross-sectional study

This study assesses the prevalence of Vitamin D deficiency and its potential association with cardiometabolic risk factors among South African adults residing in the Eastern Cape province. In this cross-sectional study, 1244 healthcare workers (HCWs) completed a self-administered questionnaire and venous blood samples were drawn at two academic hospitals in the Eastern Cape. History of hypertension and diabetes mellitus were self-reported. Participants were categorised as obese if their body mass index (BMI) ≥ 30 kg/m2. Participants were classified as having metabolic syndrome if they had hypertension, diabetes mellitus and obesity. Vitamin D [25(OH)D] deficiency was defined as venous blood concentrations < 50 nmol/L. Associations between vitamin D deficiency and participants' characteristics were assessed using multivariate logistic regression model analysis. The prevalence of vitamin D deficiency was 28.5% (n = 355), of whom 292 were female. Among the participants who were deficient in vitamin D, the prevalence of obesity, diabetes mellitus, hypertension, chronic kidney disease, and metabolic syndrome was 64.9% (n = 230), 9% (n = 32), 16.6% (n = 59), 2.3% (n = 8) and 18% (n = 64), respectively. In the adjusted multivariate logistic regression model, black Africans (AOR = 2.87; 95% CI 1.52-5.43) and individuals ≥ 42 years (AOR = 1.37; 95% CI 1.07-1.77) were more likely to exhibit vitamin D deficiency. However, there was no significant association by age, sex, and cardiometabolic markers. More than one in four healthcare workers was deficient in vitamin D among the study sample, especially the black Africans and older individuals. Further studies are needed at the population level to elucidate on the vitamin D status in the region.

Sclerostin Alters Tumor Cell Characteristics of Oral Squamous Cell Carcinoma and May Be a Key Player in Local Bone Invasion

Localized jawbone invasion is a milestone in the progression of oral squamous cell carcinoma (OSCC). The factors that promote this process are not well understood. Sclerostin is known to be involved in bone metabolism and there are preliminary reports of its involvement in bone tumors and bone metastasis. To identify a possible involvement of sclerostin in the bone invasion process of OSCC, sclerostin expression was analyzed in vitro in two different human OSCC tumor cell lines by quantitative real-time polymerase chain reaction (qRT-PCR), and the effect of recombinant human (rh)-sclerostin treatment on tumor cell capabilities was evaluated using proliferation, migration, and invasion assays. Undifferentiated human mesenchymal stem cells (hMSCs) were osteogenically differentiated and co-cultured with OSCC tumor cells to demonstrate potential interactions and migration characteristics. Sclerostin expression was evaluated in clinical cases by immunohistochemistry at the OSCC-jawbone interface in a cohort of 15 patients. Sclerostin expression was detected in both OSCC tumor cell lines in vitro and was also detected at the OSCC-jawbone interface in clinical cases. Tumor cell proliferation rate, migration and invasion ability were increased by rh-sclerostin treatment. The migration rate of tumor cells co-cultured with osteogenically differentiated hMSCs was increased. The results presented are the first data suggesting a possible involvement of sclerostin in the bone invasion process of OSCC, which deserves further investigation and may be a potential approach for drug-based tumor therapy.

[Pathology of the kidneys in malignant tumors of various localizations and antitumor therapy]

Non-tumorlesions of the kidneys in malignant neoplasms are very diverse. They can alter the results of chemotherapy and lead to death in the long term. In this regard, the related discipline of onconephrology has increasingly begun to be identified, which emphasizes the importance of diagnosing non-tumor kidney lesions in this category of patients. This review is devoted to the classification, diagnosis, course, prevention and treatment of non-tumor kidney lesions in patients with malignant neoplasms. There are four groups of lesions: mechanical damage; nephropathy due to anticancer therapy; paraneoplastic nephropathy; lesions associated with metabolic disorders. Kidney lesions in patients with malignant neoplasms are characterized by a variable course. In some cases, acute renal failure develops. Others are characterized by an asymptomatic course with an outcome in nephrosclerosis. Timely diagnosis and treatment of kidney lesions in malignant neoplasms can improve the quality of life and prognosis of patients with malignant neoplasms.

Elevated extracellular calcium ions accelerate the proliferation and migration of HepG2 cells and decrease cisplatin sensitivity

Hepatoblastoma is the most frequent liver malignancy in children. HepG2 has been discovered as a hepatoblastoma-derived cell line and tends to form clumps in culture. Intriguingly, we observed that the addition of calcium ions reduced cell clumping and disassociated HepG2 cells. The calcium signal is in connection with a series of processes critical in the tumorigenesis. Here, we demonstrated that extracellular calcium ions induced morphological changes and enhanced the epithelial-mesenchymal transition in HepG2 cells. Mechanistically, calcium ions promoted HepG2 proliferation and migration by up-regulating the phosphorylation levels of focal adhesion kinase (FAK), protein kinase B, and p38 mitogen-activated protein kinase. The inhibitor of FAK or Ca 2+/calmodulin-dependent kinase Ⅱ (CaMKⅡ) reversed the Ca 2+-induced effects on HepG2 cells, including cell proliferation and migration, epithelial-mesenchymal transition protein expression levels, and phosphorylation levels of FAK and protein kinase B. Moreover, calcium ions decreased HepG2 cells' sensitivity to cisplatin. Furthermore, we found that the expression levels of FAK and CaMKⅡ were increased in hepatoblastoma. The group with high expression levels of FAK and CaMKⅡ exhibited significantly lower ImmunoScore as well as CD8 + T and NK cells. The expression of CaMKⅡ was positively correlated with that of PDCD1 and LAG3. Correspondingly, the expression of FAK was negatively correlated with that of TNFSF9, TNFRSF4, and TNFRSF18. Collectively, extracellular calcium accelerates HepG2 cell proliferation and migration via FAK and CaMKⅡ and enhances cisplatin resistance. FAK and CaMKⅡ shape immune cell infiltration and responses in tumor microenvironments, thereby serving as potential targets for hepatoblastoma.

Efficacy of zoledronic acid for the elimination of disseminated tumor cells in a clinically relevant, spontaneously metastatic prostate cancer xenograft model

Bone metastases develop in >90 % of patients with castration-resistant prostate cancer (PCa) through complex interactions between the bone microenvironment and tumor cells. Previous androgen-deprivation therapy (ADT), which is known to cause bone loss, as well as anti-resorptive agents such as zoledronic acid (ZA), used to prevent skeletal complications, may influence these interactions and thereby the growth of disseminated tumor cells (DTC) in the bone marrow (BM). Here, a spontaneously metastatic xenograft tumor model of human PCa was further optimized to mimic the common clinical situation of ADT (castration) combined with primary tumor resection in vivo. The effects of these interventions, alone or in combination with ZA treatment, on tumor cell dissemination to the BM and other distant sites were analyzed. Metastatic burden was quantified by human-specific Alu-qPCR, bioluminescence imaging (BLI), and immunohistochemistry. Further, bone remodeling was assessed by static histomorphometry and serum parameters. Initial comparative analysis between NSG and SCID mice showed that spontaneous systemic dissemination of subcutaneous PC-3 xenograft tumors was considerably enhanced in NSG mice. Primary tumor resection and thereby prolonged observational periods resulted in a higher overall metastatic cell load at necropsy and tumor growth alone caused significant bone loss, which was further augmented by surgical castration. In addition, castrated mice showed a strong trend towards higher bone metastasis loads. Weekly treatment of mice with ZA completely prevented castration- and tumor-induced bone loss but had no effect on bone metastasis burden. Conversely, the total lung metastasis load as determined by BLI was significantly decreased upon ZA treatment. These findings provide a basis for future research on the role of ZA not only in preventing skeletal complications but also in reducing metastasis to other organs.

The bioelectrical properties of bone tissue

Understanding the bioelectrical properties of bone tissue is key to developing new treatment strategies for bone diseases and injuries, as well as improving the design and fabrication of scaffold implants for bone tissue engineering. The bioelectrical properties of bone tissue can be attributed to the interaction of its various cell lineages (osteocyte, osteoblast and osteoclast) with the surrounding extracellular matrix, in the presence of various biomechanical stimuli arising from routine physical activities; and is best described as a combination and overlap of dielectric, piezoelectric, pyroelectric and ferroelectric properties, together with streaming potential and electro-osmosis. There is close interdependence and interaction of the various electroactive and electrosensitive components of bone tissue, including cell membrane potential, voltage-gated ion channels, intracellular signaling pathways, and cell surface receptors, together with various matrix components such as collagen, hydroxyapatite, proteoglycans and glycosaminoglycans. It is the remarkably complex web of interactive cross-talk between the organic and non-organic components of bone that define its electrophysiological properties, which in turn exerts a profound influence on its metabolism, homeostasis and regeneration in health and disease. This has spurred increasing interest in application of electroactive scaffolds in bone tissue engineering, to recapitulate the natural electrophysiological microenvironment of healthy bone tissue to facilitate bone defect repair.

Cell Membrane-Anchoring Nano-Photosensitizer for Light-Controlled Calcium-Overload and Tumor-Specific Synergistic Therapy

Poor selectivity and unintended toxicity to normal organs are major challenges in calcium ion (Ca²⁺ ) overload tumor therapy. To address this issue, a cell membrane-anchoring nano-photosensitizer (CMA-nPS) is constructed for inducing tumor-specific Ca²⁺ overload through multistage endogenous Ca²⁺ homeostasis disruption under light guidance, i.e., the extracellular Ca²⁺ influx caused by cell membrane damage, followed by the intracellular Ca²⁺ imbalance caused by mitochondrial dysfunction. CMA-nPS is decorated by two types of functionalized cell membranes, the azide-modified macrophage cell membrane is used to conjugate the dibenzocyclooctyne-decorated photosensitizer, and the vesicular stomatitis virus glycoprotein (VSV-G)-modified NIH3T3 cell membrane is used to guide the anchoring of photosensitizer to the lung cancer cell membrane. The in vitro study shows that CMA-nPS mainly anchors on the cell membrane, and further causes membrane damage, mitochondrial dysfunction, as well as intracellular Ca²⁺ overload upon light irradiation. Synergistically enhanced antitumor efficiency is observed in vitro and in vivo. This study provides a new synergistic strategy for Ca²⁺ -overload-based cancer therapy, as well as a strategy for anchoring photosensitizer on the cell membrane, offering broad application prospects for the treatment of lung cancer.

Chemokines network in bone metastasis: Vital regulators of seeding and soiling

Chemokines are well equipped with chemo-attractive signals that can regulate cancer cell trafficking to specific organ sites. Currently, updated concepts have revealed the diverse role of chemokines in the biology of cancer initiation and progression. Genomic instabilities and alterations drive tumor heterogeneity, providing more options for the selection and metastatic progression to cancer cells. Tumor heterogeneity and acquired drug resistance are the main obstacles in managing cancer therapy and the primary root cause of metastasis. Studies emphasize that multiple chemokine/receptor axis are involved in cancer cell-mediated organ-specific distant metastasis. One of the persuasive mechanisms for heterogeneity and subsequent events is sturdily interlinked with the crosstalk between chemokines and their receptors on cancer cells and tissue-specific microenvironment. Among different metastatic niches, skeletal metastasis is frequently observed in the late stages of prostate, breast, and lung cancer and significantly reduces the survival of cancer patients. Therefore, it is crucial to elucidate the role of chemokines and their receptors in metastasis and bone remodeling. Here, we review the potential chemokine/receptor axis in tumorigenesis, tumor heterogeneity, metastasis, and vicious cycle in bone microenvironment.

Paraquat is an agonist of STIM1 and increases intracellular calcium levels

Paraquat (PQ) is an efficient herbicide but leads to high mortality with no antidote in mammals. PQ produces reactive oxygen species (ROS), leading to epithelial-mesenchymal transition (EMT) for pulmonary fibrosis in type II alveolar (AT II) cells. Intriguingly, strategies reducing ROS exhibit limited therapeutic effects, indicating other targets existing for PQ toxicity. Herein we report that PQ is also an agonist for STIM1 that increases intracellular calcium levels. Particularly, PQ promotes STIM1 puncta formation and association with TRPC1 or ORAI for extracellular calcium entry and thus intracellular calcium influx. Further studies reveal the importance of P584&Y586 residues in STIM1 for PQ association that facilitates STIM1 binding to TRPC1. Consequently, the STIM1-TRPC1 route facilitates PQ-induced EMT for pulmonary fibrosis as well as cell death. Our results demonstrate that PQ is an agonist of STIM1 that induces extracellular calcium entry, increases intracellular calcium levels, and thus promotes EMT in AT II cells.

Roles of calcium signaling in cancer metastasis to bone

Bone metastasis is a frequent complication for cancers and an important reason for the mortality in cancer patients. After surviving in bone, cancer cells can cause severe pain, life-threatening hypercalcemia, pathologic fractures, spinal cord compression, and even death. However, the underlying mechanisms of bone metastasis were not clear. The role of calcium (Ca2+) in cancer cell proliferation, migration, and invasion has been well established. Interestingly, emerging evidence indicates that Ca2+ signaling played a key role in bone metastasis, for it not only promotes cancer progression but also mediates osteoclasts and osteoblasts differentiation. Therefore, Ca2+ signaling has emerged as a novel therapeutical target for cancer bone metastasis treatments. Here, the role of Ca2+ channels and Ca2+-binding proteins including calmodulin and Ca2+-sensing receptor in bone metastasis, and the perspective of anti-cancer bone metastasis therapeutics via targeting the Ca2+ signaling pathway are summarized.

Stromal Co-Cultivation for Modeling Breast Cancer Dormancy in the Bone Marrow

Cancers metastasize to the bone marrow before primary tumors can be detected. Bone marrow micrometastases are resistant to therapy, and while they are able to remain dormant for decades, they recur steadily and result in incurable metastatic disease. The bone marrow microenvironment maintains the dormancy and chemoresistance of micrometastases through interactions with multiple cell types and through structural and soluble factors. Modeling dormancy in vitro can identify the mechanisms of these interactions. Modeling also identifies mechanisms able to disrupt these interactions or define novel interactions that promote the reawakening of dormant cells. The in vitro modeling of the interactions of cancer cells with various bone marrow elements can generate hypotheses on the mechanisms that control dormancy, treatment resistance and reawakening in vivo. These hypotheses can guide in vivo murine experiments that have high probabilities of succeeding in order to verify in vitro findings while minimizing the use of animals in experiments. This review outlines the existing data on predominant stromal cell types and their use in 2D co-cultures with cancer cells.

Sarm1 activation produces cADPR to increase intra-axonal Ca++ and promote axon degeneration in PIPN

Cancer patients frequently develop chemotherapy-induced peripheral neuropathy (CIPN), a painful and long-lasting disorder with profound somatosensory deficits. There are no effective therapies to prevent or treat this disorder. Pathologically, CIPN is characterized by a "dying-back" axonopathy that begins at intra-epidermal nerve terminals of sensory neurons and progresses in a retrograde fashion. Calcium dysregulation constitutes a critical event in CIPN, but it is not known how chemotherapies such as paclitaxel alter intra-axonal calcium and cause degeneration. Here, we demonstrate that paclitaxel triggers Sarm1-dependent cADPR production in distal axons, promoting intra-axonal calcium flux from both intracellular and extracellular calcium stores. Genetic or pharmacologic antagonists of cADPR signaling prevent paclitaxel-induced axon degeneration and allodynia symptoms, without mitigating the anti-neoplastic efficacy of paclitaxel. Our data demonstrate that cADPR is a calcium-modulating factor that promotes paclitaxel-induced axon degeneration and suggest that targeting cADPR signaling provides a potential therapeutic approach for treating paclitaxel-induced peripheral neuropathy (PIPN).

Network-Based Analysis to Identify Drivers of Metastatic Prostate Cancer Using GoNetic

Most known driver genes of metastatic prostate cancer are frequently mutated. To dig into the long tail of rarely mutated drivers, we performed network-based driver identification on the Hartwig Medical Foundation metastatic prostate cancer data set (HMF cohort). Hereto, we developed GoNetic, a method based on probabilistic pathfinding, to identify recurrently mutated subnetworks. In contrast to most state-of-the-art network-based methods, GoNetic can leverage sample-specific mutational information and the weights of the underlying prior network. When applied to the HMF cohort, GoNetic successfully recovered known primary and metastatic drivers of prostate cancer that are frequently mutated in the HMF cohort (TP53, RB1, and CTNNB1). In addition, the identified subnetworks contain frequently mutated genes, reflect processes related to metastatic prostate cancer, and contain rarely mutated driver candidates. To further validate these rarely mutated genes, we assessed whether the identified genes were more mutated in metastatic than in primary samples using an independent cohort. Then we evaluated their association with tumor evolution and with the lymph node status of the patients. This resulted in forwarding several novel putative driver genes for metastatic prostate cancer, some of which might be prognostic for disease evolution.

Paraquat but not diquat induces TGF-β expression and thus activates calcium-NFAT axis for epithelial-mesenchymal transition

Paraquat (PQ) and diquat (DQ), two highly efficient herbicides sharing similar chemical backbone, both induce reactive oxygen species and are highly toxic to humans and livestock, however, PQ but not DQ poisoning result in pulmonary fibrosis, the leading cause of high mortality rate in patients suffering PQ toxicity. Understanding the unique mechanism of PQ different from DQ therefore would provide potential strategies to reduce PQ-induced pulmonary fibrosis. Here, we identified that PQ but not DQ continuously upregulates TGF-β expression in alveolar type II (AT II) cells. Importantly, such high expression of TGF-β increases cytosolic calcium levels and further promotes the activation of calcineurin-NFAT axis. TGF-β mainly activates NFATc1 and NFATc2, but not NFATc3 or NFATc4. Administration of the inhibitors targeting cytosolic calcium or calcineurin largely reverses PQ-induced epithelial-mesenchymal transition (EMT), whereas DQ has little effects on activation of NFAT and EMT. Ultimately, PQ poisoned patients exhibit significantly reduced blood calcium levels compared to DQ poisoning, possibly via the large usage of calcium by AT II cells. All in all, we found a vicious cycle that the upregulated TGF-β in PQ-induced EMT further aggravates EMT via promotion of the calcium-calcineurin axis, which could be potential drug targets for treating PQ-induced pulmonary fibrosis.

Acid Microenvironment in Bone Sarcomas

Simple Summary

Although rare, malignant bone sarcomas have devastating clinical implications for the health and survival of young adults and children. To date, efforts to identify the molecular drivers and targets have focused on cancer cells or on the interplay between cancer cells and stromal cells in the tumour microenvironment. On the contrary, in the current literature, the role of the chemical-physical conditions of the tumour microenvironment that may be implicated in sarcoma aggressiveness and progression are poorly reported and discussed. Among these, extracellular acidosis is a well-recognized hallmark of bone sarcomas and promotes cancer growth and dissemination but data presented on this topic are fragmented. Hence, we intended to provide a general and comprehensive overview of the causes and implications of acidosis in bone sarcoma.

Abstract

In bone sarcomas, extracellular proton accumulation is an intrinsic driver of malignancy. Extracellular acidosis increases stemness, invasion, angiogenesis, metastasis, and resistance to therapy of cancer cells. It reprograms tumour-associated stroma into a protumour phenotype through the release of inflammatory cytokines. It affects bone homeostasis, as extracellular proton accumulation is perceived by acid-sensing ion channels located at the cell membrane of normal bone cells. In bone, acidosis results from the altered glycolytic metabolism of bone cancer cells and the resorption activity of tumour-induced osteoclasts that share the same ecosystem. Proton extrusion activity is mediated by extruders and transporters located at the cell membrane of normal and transformed cells, including vacuolar ATPase and carbonic anhydrase IX, or by the release of highly acidic lysosomes by exocytosis. To date, a number of investigations have focused on the effects of acidosis and its inhibition in bone sarcomas, including studies evaluating the use of photodynamic therapy. In this review, we will discuss the current status of all findings on extracellular acidosis in bone sarcomas, with a specific focus on the characteristics of the bone microenvironment and the acid-targeting therapeutic approaches that are currently being evaluated.

Bone marrow/bone pre-metastatic niche for breast cancer cells colonization: The role of mesenchymal stromal cells

Breast cancer is one of the most common oncological pathologies in women worldwide. While its early diagnosis has considerably improved, about 70 % of advanced patients develop bone metastases with a high mortality rate. Several authors demonstrated that primary breast cancer cells prepare their future metastatic niche -known as the pre-metastatic niche- to turn it into an "optimal soil" for colonization. The role of the different cellular components of the bone marrow/bone niche in bone metastasis has been well described. However, studying the changes that occur in this microenvironment before tumor cells arrival has become a novel research field. Therefore, the purpose of this review is to describe the current knowledge about the modulation of the normal bone marrow/bone niche by the primary breast tumor, in particular, highlighting the role of mesenchymal stem/stromal cells in transforming this soil into a pre-metastatic niche for breast cancer cells colonization.

Organ tropism in solid tumor metastasis: an updated review

Tumors are equipped with a highly complex machinery of interrelated events so as to adapt to hazardous conditions, preserve a growing cell mass and thrive at the site of metastasis. Tumor cells display metastatic propensity toward specific organs where the stromal milieu is appropriate for their further colonization. Effective colonization relies on the plasticity of tumor cells in adapting to the conditions of the new area by reshaping their epigenetic landscape. Breast cancer cells, for instance, are able to adopt brain-like or epithelial/osteoid features in order to pursue effective metastasis into brain and bone, respectively. The aim of this review is to discuss recent insights into organ tropism in tumor metastasis, outlining potential strategies to address this driver of tumor aggressiveness.

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.

Gene expression analysis of human prostate cell lines with and without tumor metastasis suppressor CD82

BACKGROUND

Tetraspanin CD82 is a tumor metastasis suppressor that is known to down regulate in various metastatic cancers. However, the exact mechanism by which CD82 prevents cancer metastasis is unclear. This study aims to identify genes that are regulated by CD82 in human prostate cell lines.

METHODS

We used whole human genome microarray to obtain gene expression profiles in a normal prostate epithelial cell line that expressed CD82 (PrEC-31) and a metastatic prostate cell line that does not express CD82 (PC3). Then, siRNA silencing was used to knock down CD82 expression in PrEC-31 while CD82 was re-expressed in PC3 to acquire differentially-expressed genes in the respective cell line.

RESULTS

Differentially-expressed genes with a P < 0.05 were identified in 3 data sets: PrEC-31 (+CD82) vs PrEC-31(-CD82), PC3-57 (+CD82) vs. PC3-5 V (-CD82), and PC3-29 (+CD82) vs. PC3-5 V (-CD82). Top 25 gene lists did not show overlap within the data sets, except (CALB1) the calcium binding protein calbindin 1 which was significantly up-regulated (2.8 log fold change) in PrEC-31 and PC3-29 cells that expressed CD82. Other most significantly up-regulated genes included serine peptidase inhibitor kazal type 1 (SPINK1) and polypeptide N-acetyl galactosaminyl transferase 14 (GALNT14) and most down-regulated genes included C-X-C motif chemokine ligand 14 (CXCL14), urotensin 2 (UTS2D), and fibroblast growth factor 13 (FGF13). Pathways related with cell proliferation and angiogenesis, migration and invasion, cell death, cell cycle, signal transduction, and metabolism were highly enriched in cells that lack CD82 expression. Expression of two mutually inclusive genes in top 100 gene lists of all data sets, runt-related transcription factor (RUNX3) and trefoil factor 3 (TFF3), could be validated with qRT-PCR.

CONCLUSION

Identification of genes and pathways regulated by CD82 in this study may provide additional insights into the role that CD82 plays in prostate tumor progression and metastasis, as well as identify potential targets for therapeutic intervention.

Identifying MMP14 and COL12A1 as a potential combination of prognostic biomarkers in pancreatic ductal adenocarcinoma using integrated bioinformatics analysis

Background

Pancreatic ductal adenocarcinoma (PDAC) is a fatal malignant neoplasm. It is necessary to improve the understanding of the underlying molecular mechanisms and identify the key genes and signaling pathways involved in PDAC.

Methods

The microarray datasets GSE28735, GSE62165, and GSE91035 were downloaded from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified by integrated bioinformatics analysis, including protein-protein interaction (PPI) network, Gene Ontology (GO) enrichment, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The PPI network was established using the Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape software. GO functional annotation and KEGG pathway analyses were performed using the Database for Annotation, Visualization, and Integrated Discovery. Hub genes were validated via the Gene Expression Profiling Interactive Analysis tool (GEPIA) and the Human Protein Atlas (HPA) website.

Results

A total of 263 DEGs (167 upregulated and 96 downregulated) were common to the three datasets. We used STRING and Cytoscape software to establish the PPI network and then identified key modules. From the PPI network, 225 nodes and 803 edges were selected. The most significant module, which comprised 11 DEGs, was identified using the Molecular Complex Detection plugin. The top 20 hub genes, which were filtered by the CytoHubba plugin, comprised FN1, COL1A1, COL3A1, BGN, POSTN, FBN1, COL5A2, COL12A1, THBS2, COL6A3, VCAN, CDH11, MMP14, LTBP1, IGFBP5, ALB, CXCL12, FAP, MATN3, and COL8A1. These genes were validated using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, and the encoded proteins were subsequently validated using the HPA website. The GO analysis results showed that the most significantly enriched biological process, cellular component, and molecular function terms among the 20 hub genes were cell adhesion, proteinaceous extracellular matrix, and calcium ion binding, respectively. The KEGG pathway analysis showed that the 20 hub genes were mainly enriched in ECM-receptor interaction, focal adhesion, PI3K-Akt signaling pathway, and protein digestion and absorption. These findings indicated that FBN1 and COL8A1 appear to be involved in the progression of PDAC. Moreover, patient survival analysis performed via the GEPIA using TCGA and GTEx databases demonstrated that the expression levels of COL12A1 and MMP14 were correlated with a poor prognosis in PDAC patients (p < 0.05).

Conclusions

The results demonstrated that upregulation of MMP14 and COL12A1 is associated with poor overall survival, and these might be a combination of prognostic biomarkers in PDAC.

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.

Role of αVβ3 in Prostate Cancer: Metastasis Initiator and Important Therapeutic Target

In prostate cancer, distant organ metastasis is the leading cause of patient death. Although the mechanism of malignant tumor metastasis is unclear, studies have confirmed that integrin αVβ3 plays an important role in this process. In prostate cancer, αVβ3 mediates adhesion, invasion, immune escape and neovascularization through interactions with different ligands. Among these ligands and in addition to proteins that are directly related to tumor invasion, other proteins that contain the RGD structure could also bind to αVβ3 and cause a number of biological effects. In this article, we summarized the ligand and downstream proteins related to αVβ3-mediated prostate cancer metastasis as well as some diagnostic and therapeutic measures targeting αVβ3.

Breast Cancer Derived Extracellular Vesicles in Bone Metastasis Induction and Their Clinical Implications as Biomarkers

Cancer incidence and mortality are rapidly growing worldwide. The main risk factors for cancer can be associated with aging as well as the growth of the population and socioeconomic condition. Breast cancer, a crucial public health problem, is the second cause of death among women. About 70% of patients with advanced breast cancer have bone metastases. In bone metastasis, cancer cells and osteoclasts form a vicious cycle: cancer cells promote osteoclast differentiation and activation that, in turn, induce cancer cell seeding and proliferation in the bone. Growing evidence shows that extracellular vesicles (EVs) play a key role in carcinogenesis, proliferation, pre-metastatic niche formation, angiogenesis, metastasis, and chemoresistance in several tumors, such as breast, lung, prostate, and liver cancer. Here, we discuss the role of EVs released by breast cancer cells, focusing on bone metastasis induction and their clinical implications as biomarkers.