Elevated Orai1 and STIM1 expressions upregulate MACC1 expression to promote tumor cell proliferation, metabolism, migration, and invasion in human gastric cancer

HERG1 promotes esophageal squamous cell carcinoma growth and metastasis through TXNDC5 by activating the PI3K/AKT pathway

Background

The human ether a-go-go-related gene 1 (HERG1) is involved in tumor progression; however, its role in esophageal squamous cell carcinoma (ESCC) is not well studied. This study investigated HERG1 function in ESCC progression and elucidated the underlying mechanisms.

Methods

The prognostic value of HERG1 was determined by immunohistochemistry in ESCC biopsies. Cell growth and proliferation were analyzed by colony formation and methyl thiazolyl tetrazolium assays. Cell migration and invasion were analyzed by wound healing and Boyden transwell assays. Epithelial-mesenchymal transition (EMT) was evaluated by immunoblotting and quantitative polymerase chain reaction (qPCR). A xenograft mouse model was used to validate the tumorigenic and metastatic roles of HERG1 in vivo.

Results

HERG1 expression was overall higher in ESCC tissues compared to adjacent non-tumor tissues. A retrospective analysis of 349 patients with ESCC (stages I–IV) confirmed increased HERG1 expression was associated with disease progression and higher mortality rate. The overall survival of the patients was significantly worse when their tumors displayed higher HERG1 expression. HERG1 knockdown reduced tumor growth and metastasis in athymic mice. HERG1 affected the proliferation, migration, and invasion of two ESCC cell lines (TE-1 and KYSE-30). Changes in HERG1 expression affected the expression of cell cycle- and EMT-related proteins; these effects were reversed by altering the expression of thioredoxin domain-containing protein 5 (TXNDC5), which is also associated with the clinicopathological characteristics of patients with ESCC and is relevant to HERG1 in pathological biopsies. Additionally, HERG1 expression altered phosphoinositide 3-kinase (PI3K) and AKT phosphorylation, thereby affecting TXNDC5 expression.

Conclusions

HERG1 contributes to poor prognosis in patients with ESCC by promoting ESCC cell proliferation, migration, and invasion via TXNDC5 through the PI3K/AKT signaling pathway. Our findings provided novel insights into the pathology of ESCC and role of HERG1 in tumor progression, suggesting that targeting HERG1 has potential diagnostic and therapeutic value for ESCC treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1284-y) contains supplementary material, which is available to authorized users.

An Updated Review of Oral Cancer Stem Cells and Their Stemness Regulation

Cancer stem cells (CSCs; also known as tumor-initiating cells) are a small population of cancer cells that retain characteristics similar to those of normal stem cells. CSCs are known to be responsible for metastasis, drug resistance, and cancer recurrence. Thus, controlling CSCs may provide an effective therapeutic intervention that inhibits tumor growth and aggressiveness. Despite the importance of targeting CSCs in cancer therapy, the detailed nature of oral CSCs remains underexplored. This article reviews the current understanding of oral CSCs, with emphasis on recent advances in novel signaling pathways involved in their stemness regulation.

Store-Operated Ca2+ Entry in Tumor Progression: From Molecular Mechanisms to Clinical Implications

The remodeling of Ca²⁺ homeostasis has been implicated as a critical event in driving malignant phenotypes, such as tumor cell proliferation, motility, and metastasis. Store-operated Ca²⁺ entry (SOCE) that is elicited by the depletion of the endoplasmic reticulum (ER) Ca²⁺ stores constitutes the major Ca²⁺ influx pathways in most nonexcitable cells. Functional coupling between the plasma membrane Orai channels and ER Ca²⁺-sensing STIM proteins regulates SOCE activation. Previous studies in the human breast, cervical, and other cancer types have shown the functional significance of STIM/Orai-dependent Ca²⁺ signals in cancer development and progression. This article reviews the information on the regulatory mechanisms of STIM- and Orai-dependent SOCE pathways in the malignant characteristics of cancer, such as proliferation, resistance, migration, invasion, and metastasis. The recent investigations focusing on the emerging importance of SOCE in the cells of the tumor microenvironment, such as tumor angiogenesis and antitumor immunity, are also reviewed. The clinical implications as cancer therapeutics are discussed.

miR-4725-3p targeting stromal interacting molecule 1 signaling is involved in xanthohumol inhibition of glioma cell invasion

Glioblastoma multiforme is the most common brain tumor in adults. Because of its highly invasive nature, it is not easy to treat, resulting in high mortality rates. Stromal interacting molecule 1 (Stim1) plays important roles in regulating store-operated Ca²⁺ entry, and controls invasion by cancer cells. However, the mechanisms and functions of Stim1 in glioma progression are still unclear. In this study, we investigated the effects of targeting Stim1 expression on glioma cell invasion. By analyzing profiles of glioblastoma multiforme patients from RNA-sequencing data in The Cancer Genome Atlas, higher expression levels of STIM1 were correlated with the poor survival. Furthermore, signaling pathways associated with tumor malignancy, including the epithelial-to-mesenchymal transition (EMT), were activated in patients with high STIM1 expression according to gene set enrichment analyses. Higher Stim1 levels were found in glioma cells compared to human astrocytes, and these higher levels enhanced glioma cell invasion. Xanthohumol (XN), a prenylated flavonoid extracted from the hop plant Humulus lupulus L. (Cannabaceae), significantly reduced cell invasion through inhibiting Stim1 expression. From an micro(mi)RNA array analysis, miR-4725-3p was up-regulated by XN treatment. Over-expression of miR-4725-3p inhibited glioma cell invasion via directly targeting the 3'-untranslated region of STIM1. The extracellular signal-regulated kinase/c-Fos pathway was also validated to participate in XN-up-regulated miR-4725-3p expression according to promoter and chromatin immunoprecipitation assays. These results emphasize that miR-4725-3p-inhibited STIM1 signaling is involved in XN-attenuated glioma cell invasion. These findings may provide insights into novel therapeutic strategies for future glioblastoma therapy and drug development. Open Data: Materials are available on https://cos.io/our-services/open-science-badges/ https://osf.io/93n6m/.

TRPV2 Calcium Channel Gene Expression and Outcomes in Gastric Cancer Patients: A Clinically Relevant Association

Gastric cancer (GC) is characterized by poor efficacy and the modest clinical impact of current therapies. Apoptosis evasion represents a causative factor for treatment failure in GC as in other cancers. Since intracellular calcium homeostasis regulation has been found to be associated with apoptosis resistance, the aberrant expression of intracellular calcium regulator genes (CaRGs) could have a prognostic value in GC patients. We analyzed the association of the expression levels of 98 CaRGs with prognosis by the log-rank test in a collection of 1524 GC samples from four gene expression profiling datasets. We also evaluated differential gene expression in comparison with normal stomach tissue, and then we crossed results with tissue microarrays from the Human Protein Atlas. Among the investigated CaRGs, patients with high levels of TRPV2 expression were characterized by a shorter overall survival. TRPV2 expression was found to increase according to tumor stage. Both mRNA and protein levels were significantly higher in tumor than normal stomach samples. TRPV2 was also associated with poor prognosis in the Lauren's intestinal type GC and in patients treated with adjuvant therapy. Overall, we highlighted the relevance of TRPV2 not only as a prognostic biomarker but also as a potential therapeutic target to improve GC treatment efficacy.

MACC1-the first decade of a key metastasis molecule from gene discovery to clinical translation

Deciphering the paths to metastasis and identifying key molecules driving this process is one important issue for understanding and treatment of cancer. Such a key driver molecule is Metastasis Associated in Colon Cancer 1 (MACC1). A decade long research on this evolutionarily conserved molecule with features of a transcription factor as well as an adapter protein for versatile protein-protein interactions has shown that it has manifold properties driving tumors to their metastatic stage. MACC1 transcriptionally regulates genes involved in epithelial-mesenchymal transition (EMT), including those which are able to directly induce metastasis like c-MET, impacts tumor cell migration and invasion, and induces metastasis in solid cancers. MACC1 has proven as a valuable biomarker for prognosis of metastasis formation linked to patient survival and gives promise to also act as a predictive marker for individualized therapies in a broad variety of cancers. This review discusses the many features of MACC1 in the context of the hallmarks of cancer and the potential of this molecule as biomarker and novel therapeutic target for restriction and prevention of metastasis.

STIM-Orai Channels and Reactive Oxygen Species in the Tumor Microenvironment

The tumor microenvironment (TME) is shaped by cancer and noncancerous cells, the extracellular matrix, soluble factors, and blood vessels. Interactions between the cells, matrix, soluble factors, and blood vessels generate this complex heterogeneous microenvironment. The TME may be metabolically beneficial or unbeneficial for tumor growth, it may favor or not favor a productive immune response against tumor cells, or it may even favor conditions suited to hijacking the immune system for benefitting tumor growth. Soluble factors relevant for TME include oxygen, reactive oxygen species (ROS), ATP, Ca2+, H⁺, growth factors, or cytokines. Ca2+ plays a prominent role in the TME because its concentration is directly linked to cancer cell proliferation, apoptosis, or migration but also to immune cell function. Stromal-interaction molecules (STIM)-activated Orai channels are major Ca2+ entry channels in cancer cells and immune cells, they are upregulated in many tumors, and they are strongly regulated by ROS. Thus, STIM and Orai are interesting candidates to regulate cancer cell fate in the TME. In this review, we summarize the current knowledge about the function of ROS and STIM/Orai in cancer cells; discuss their interdependencies; and propose new hypotheses how TME, ROS, and Orai channels influence each other.

miR-185 silencing promotes the progression of atherosclerosis via targeting stromal interaction molecule 1

BACKGROUND

Atherosclerosis (AS) is a major risk factor for cardiovascular disease. microRNAs play a key role in gene regulation in the formation and development of atherosclerotic plaques. Herein, the role and target gene of miR-185 in AS were explored.

MATERIALS AND METHODS

Cell viability, migration and invasion were examined by cell counting kit-8 (CCK-8) and transwell assay. The relative luciferase activity was measured by luciferase reporter assay. The levels of miR-185, STIM1, vascular endothelial growth factor (VEGF) and matrix metalloprotein-9 (MMP-9) were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot.

RESULTS

The results revealed that ox-LDL decreased miR-185 expression, and enhanced STIM1 expression in MOVAS cells, as well promoted cell viability, migration and invasion. 3'-UTR of STIM1 contained miR-185 binding site according to the Targetscan. miR-185 silencing or STIM1 overexpression promoted the viability, migration and invasion of ox-LDL-induced MOVAS cells. miR-185 overexpression or STIM1 silencing had the opposite effect. Besides, miR-185 silencing up-regulated the levels of VEGF and MMP-9 in vitro, and increased the lesions of arterial wall tissues and STIM1 positive rate in vivo. However, STIM1 silencing reversed these effects.

CONCLUSIONS

Sum up, STIM1 was a potential target gene of miR-185 in AS. Knockdown of miR-185 facilitated the progression of AS through enhancing cell proliferation, migration and invasion via targeting STIM1. The research provides a novel view of miR-185/STIM1 axis function in AS development, and this targeting method may prevent and treat AS.

ORAI channels and cancer

Cancer is a major cause of death. The diversity of cancer types and the propensity of cancers to acquire resistance to therapies, including new molecularly targeted and immune-based therapies, drives the search for new ways to understand cancer progression. The remodelling of calcium (Ca²⁺) signalling and the role of the Ca²⁺ signal in controlling key events in cancer cells such as proliferation, invasion and the acquisition of resistance to cell death pathways is well established. Most of the work defining such changes has focused on Ca²⁺ permeable Transient Receptor Potential (TRP) Channels and some voltage gated Ca²⁺ channels. However, the identification of ORAI channels, a little more than a decade ago, has added a new dimension to how a Ca²⁺ influx pathway can be remodelled in some cancers and also how calcium signalling could contribute to tumour progression. ORAI Ca²⁺ channels are now an exemplar for how changes in the expression of specific isoforms of a Ca²⁺ channel component can occur in cancer, and how such changes can vary between cancer types (e.g. breast cancer versus prostate cancer), and even subtypes (e.g. oestrogen receptor positive versus oestrogen receptor negative breast cancers). ORAI channels and store operated Ca²⁺ entry are also highlighting the diverse roles of Ca²⁺ influx pathways in events such as the growth and metastasis of cancers, the development of therapeutic resistance and the contribution of tumour microenvironmental factors in cancer progression. In this review we will highlight some of the studies that have provided evidence for the need to deepen our understanding of ORAI Ca²⁺ channels in cancer. Many of these studies have also suggested new ways on how we can exploit the role of ORAI channels in cancer relevant processes to develop or inform new therapeutic strategies.

Molecular alterations of cancer cell and tumour microenvironment in metastatic gastric cancer

The term metastasis is widely used to describe the endpoint of the process by which tumour cells spread from the primary location to an anatomically distant site. Achieving successful dissemination is dependent not only on the molecular alterations of the cancer cells themselves, but also on the microenvironment through which they encounter. Here, we reviewed the molecular alterations of metastatic gastric cancer (GC) as it reflects a large proportion of GC patients currently seen in clinic. We hope that further exploration and understanding of the multistep metastatic cascade will yield novel therapeutic targets that will lead to better patient outcomes.

High salt induces P-glycoprotein mediated treatment resistance in breast cancer cells through store operated calcium influx

Recent evidence from our laboratory has demonstrated that high salt (Δ0.05 M NaCl) induced inflammatory response and cancer cell proliferation through salt inducible kinase-3 (SIK3) upregulation. As calcium influx is known to effect inflammatory response and drug resistance, we examined the impact of high salt on calcium influx in breast cancer cells. Treatment of MCF-7 and MDA-MB-231 cells with high salt induced an enhanced intracellular calcium intensity, which was significantly decreased by store operated calcium entry (SOCE) inhibitor co-treatment. Further, high salt induced P-glycoprotein (P-gp) mediated paclitaxel drug resistance in breast cancer cells. Murine tumor studies demonstrated that injection of MCF-7 cells cultured in high salt, exerted higher tumorigenicity compared to the basal cultured counterpart. Knock down of SIK3 by specific shRNA inhibited tumorigenicty, expression of SOCE regulators and P-gp activity, suggesting SIK3 is an upstream mediator of SOCE induced calcium influx. Furthermore, small molecule inhibitor, prostratin, exerted anti-tumor effect in murine models through SIK3 inhibition. Taken together, we conclude that SIK3 is an upstream regulator of store operated calcium entry proteins, Orai1 and STIM1, and mediates high salt induced inflammatory cytokine responses and P-gp mediated drug resistance. Therefore, small molecule inhibitors, such as prostratin, could offer novel anti-cancer approaches.

Orai1 is critical for Notch-driven aggressiveness under hypoxic conditions in triple-negative breast cancers

It is believed that hypoxia stimulates triple-negative breast cancers (TNBCs) metastasis, which is associated with a poor prognosis. However, the underlying mechanism remains unclear. Here, we demonstrated that hypoxia up-regulates both the levels of Orai1 and Notch1, and the increase in Orai1 is mediated by Notch1 signaling in TNBCs. Functionally, Orai1 caused a sustained elevation of intracellular Ca²⁺ via Store-operated Ca²⁺ entry (SOCE), then activated the calcineurin-nuclear factor of activated T-cell 4 (NFAT4, also named NFATc3) in hypoxic TNBCs. Furthermore, pharmacologic inhibition or gene-silencing studies showed that the aggressiveness mediated by Orai1 during hypoxia is dependent on the Notch1/Orai1/SOCE/NFAT4 signaling. Moreover, Orai1 signaling also mediated hypoxia-induced angiogenesis in TNBCs. Thus, our results revealed a novel role of Orai1 as an inducer of aggression and angiogenesis under hypoxic conditions, and this suggests a novel mechanism of hypoxia-induced invasion. It may be worthwhile to further explore the potential of using Orai1 signaling as new target for anti-tumor therapy in TNBCs.

The store-operated calcium channels in cancer metastasis: from cell migration, invasion to metastatic colonization

Store-operated calcium entry (SOCE) is the predominant calcium entry mechanism in most cancer cells. SOCE is mediated by the endoplasmic reticulum calcium sensor STIMs (STIM1 and 2) and plasma membrane channel forming unit Orais (Orai 1-3). In recent years there is increasing evidence indicating that SOCE in cancer cells is dysregulated to promote cancer cell migration, invasion and metastasis. The overexpression of STIM and Orai proteins has been reported to correlate with the metastatic progression of various cancers. The hyperactive SOCE may promote metastatic dissemination and colonization by reorganizing the actin cytoskeleton, degrading the extracellular matrix and remodeling the tumor microenvironment. Here we discuss how these recent progresses provide novel insights to our understanding of tumor metastasis.

FGF2 promotes metastasis of uveal melanoma cells via store-operated calcium entry

Uveal melanoma (UM), the most common primary intraocular malignancy in adults, is highly metastatic and associated with dismal prognosis. Fibroblast growth factor 2 (FGF2) has been shown to induce cell proliferation and angiogenesis of melanoma and other malignancies. However, the expression of FGF2 in UM and its effects on melanoma cell migration are not well known. In this study, we found FGF2 expression was related to UM histological subtype and presence of metastasis. In vitro experiments showed that FGF2 treatment caused increased horizontal and vertical migration and F-actin cytoskeleton assembly as well as decreased adhesive activity of MUM2B cells, together with increased intracellular calcium concentration and expression of ORAI1 and STIM1 – two key regulatory proteins of store-operated calcium entry (SOCE). The mouse xenograft model showed that MUM2B cells with FGF2 stimulation grew into larger tumor masses and were prone to metastasis. In addition, the SOCE inhibitor 2-aminoethoxydiphenyl borate (2-APB) reversed all of these effects of FGF2. Finally, human UM samples and mouse xenograft model samples were used to confirm the correlation of FGF2 with ORAI1 and STIM1 expression. Taken together, our study suggests that FGF2 promotes metastasis of UM via SOCE.

TOP1MT deficiency promotes GC invasion and migration via the enhancements of LDHA expression and aerobic glycolysis

Aerobic glycolysis plays an important role in cancer progression. New target genes regulating cancer aerobic glycolysis must be explored to improve patient prognosis. Mitochondrial topoisomerase I (TOP1MT) deficiency suppresses glucose oxidative metabolism but enhances glycolysis in normal cells. Here, we examined the role of TOP1MT in gastric cancer (GC) and attempted to determine the underlying mechanism. Using in vitro and in vivo experiments and analyzing the clinicopathological characteristics of patients with GC, we found that TOP1MT expression was lower in GC samples than in adjacent nonmalignant tissues. TOP1MT knockdown significantly promoted GC migration and invasion in vitro and in vivo Importantly, TOP1MT silencing increased glucose consumption, lactate production, glucose transporter 1 expression and the epithelial-mesenchymal transition (EMT) in GC. Additionally, regulation of glucose metabolism induced by TOP1MT was significantly associated with lactate dehydrogenase A (LDHA) expression. A retrospective analysis of clinical data from 295 patients with GC demonstrated that low TOP1MT expression was associated with lymph node metastasis, recurrence and high mortality rates. TOP1MT deficiency enhanced glucose aerobic glycolysis by stimulating LDHA to promote GC progression.

Suppression of STIM1 inhibits the migration and invasion of human prostate cancer cells and is associated with PI3K/Akt signaling inactivation

Store-operated calcium entry (SOCE) plays an important role in the invasion and migration of cancer cells. Stromal-interacting molecule 1 (STIM1) is a critical component in the SOCE. STIM1 has been attracting more and more attention due to its oncogenic potential. STIM1 inhibition suppresses cell proliferation, migration and invasion in a variety of cancer models both in vitro and in vivo. However, the role of STIM1 in prostate carcinogenesis, in particular, in tumor migration and invasion is unclear. Herein, we downregulated STIM1 in prostate cancer cells by lentivirus-mediated short hairpin (shRNA), and then studied its impacts on cell migration and invasion. We found that migration and invasion of prostate cancer cells were significantly inhibited after the suppression of STIM1. Furthermore, we demonstrated that the PI3K/Akt signaling pathway was inactivated by STIM1 knockdown. The PI3K inhibitor LY294002 synergized with STIM1 knockdown to inhibit cell motility. Our results revealed that STIM1 may act as a novel regulator to promote migration and invasion of prostate cancer cells and is associated with the activation of the PI3K/Akt signaling pathway.

Selenoproteins and Metastasis

Cancer survival is largely impacted by the dissemination of cancer cells from the original tumor site to secondary tissues or organs through metastasis. Targets for antimetastatic therapies have recently become a focus of research, but progress will require a better understanding of the molecular mechanisms driving metastasis. Selenoproteins play important roles in many of the cellular activities underlying metastasis including cell adhesion, matrix degradation and migration, invasion into the blood and extravasation into secondary tissues, and subsequent proliferation into metastatic tumors along with the angiogenesis required for growth. In this review the roles identified for different selenoproteins in these steps and how they may promote or inhibit metastatic cancers is discussed. These roles include selenoenzyme modulation of redox tone and detoxification of reactive oxygen species, calcium homeostasis and unfolded protein responses regulated by endoplasmic reticulum selenoproteins, and the multiple physiological responses influenced by other selenoproteins.

MACC1 induces autophagy to regulate proliferation, apoptosis, migration and invasion of squamous cell carcinoma

Metastasis-associated colon cancer-1 (MACC1) plays an important role in cancer development, but the role and mechansim of MACC1 in squamous cell carcinoma (ESCC) remain unclear. In this study, we found that MACC1 expression was increased in ESCC, and correlated with lymph node metastasis. MACC1 knockdown suppresed ESCC cell proliferation, metastasis and enchanced cell apoptosis. Moreover, MACC1 knockdown inhibited ESCC cell autophagy, and 3-methyladenine was able to rescue MACC1-induced malignant phenotype of ESCC cells. Furthermore, MACC1 knockdown inactivated AMPK-ULK1 signaling pathway, and metformin could rescue MACC1-induced autophagy in ESCC cells. Collectively, this study found that upregulation of MACC1 in ESCC was associated with lymph node metastasis of patients, and MACC1 regulated ESCC cell proliferation, apoptosis, migration and invasion mainly through AMPK-ULK1 induced autophagy.

The calcium-cancer signalling nexus

The calcium signal is a powerful and multifaceted tool by which cells can achieve specific outcomes. Cellular machinery important in tumour progression is often driven or influenced by changes in calcium ions; in some cases this regulation occurs within spatially defined regions. Over the past decade there has been a deeper understanding of how calcium signalling is remodelled in some cancers and the consequences of calcium signalling on key events such as proliferation, invasion and sensitivity to cell death. Specific calcium signalling pathways have also now been identified as playing important roles in the establishment and maintenance of multidrug resistance and the tumour microenvironment.

Bapx1 mediates transforming growth factor-β- induced epithelial-mesenchymal transition and promotes a malignancy phenotype of gastric cancer cells

The homeoprotein Bapx1 is an important regulator of gastroduodenal tract morphogenesis. Here, we investigated how Bapx1 influences gastric cancer (GC) prognosis and elucidated the underlying mechanisms. Bapx1 expression was greater in GC tissues compared to adjacent non-tumor tissues and expression was positively correlated with mortality, lymph node and distance metastasis. Silencing Bapx1 diminished cell invasion/migration and decreased mesenchymal phenotypes. Transforming growth factor-β (TGF-β) induced Bapx1 expression and epithelial-mesenchymal transition (EMT) in GC cells. However, down-regulated Bapx1 reversed TGF-β induced invasion, migration, morphological changes, and EMT. In summary, Bapx1 indicates poor prognosis for GC by promoting tumor migration and invasion via TGF-β-induced EMT.

Ion channels or aquaporins as novel molecular targets in gastric cancer

Gastric cancer (GC) is a common disease with few effective treatment choices and poor prognosis, and has the second-highest mortality rates among all cancers worldwide. Dysregulation and/or malfunction of ion channels or aquaporins (AQPs) are common in various human cancers. Furthermore, ion channels are involved in numerous important aspects of the tumor aggressive phonotype, such as proliferation, cell cycle, apoptosis, motility, migration, and invasion. Indeed, by localizing in the plasma membrane, ion channels or AQPs can sense and respond to extracellular environment changes; thus, they play a crucial role in cell signaling and cancer progression. These findings have expanded a new area of pharmaceutical exploration for various types of cancer, including GC. The involvement of multiple ion channels, such as voltage-gated potassium and sodium channels, intracellular chloride channels, ‘transient receptor potential’ channels, and AQPs, which have been shown to facilitate the pathogenesis of other tumors, also plays a role in GC. In this review, an overview of ion channel and aquaporin expression and function in carcinogenesis of GC is presented. Studies of ion channels or AQPs will advance our understanding of the molecular genesis of GC and may identify novel and effective targets for the clinical application of GC.

Long non-coding RNA MALAT1 promotes gastric cancer tumorigenicity and metastasis by regulating vasculogenic mimicry and angiogenesis

MALAT1 is an oncogenic long non-coding RNA that has been found to promote the proliferation of many malignant cell types and non-malignant human umbilical vein endothelial cells (HUVECs). However, the functions of MALAT1 in vasculogenic mimicry (VM) and angiogenesis and the potential mechanisms responsible have not yet been investigated in any malignancy. Here, in situ hybridization and CD31/periodic acid-Schiff double staining of 150 gastric cancer (GC) clinical specimens revealed that MALAT1 expression was tightly associated with densities of VM and endothelial vessels. MALAT1 knockdown markedly reduced GC cell migration, invasion, tumorigenicity, metastasis, and VM, while restricting HUVEC angiogenesis and increasing vascular permeability. Moreover, MALAT1 was found to regulate expression of VE-cadherin, β-catenin, MMPs 2 and 9, MT1-MMP, p-ERK, p-FAK, and p-paxillin, which have been established as classical markers of VM and angiogenesis and components of associated signaling pathways. Consistent with this, the p-ERK inhibitors U0126 and PD98059 both effectively blocked GC cell VM. In conclusion, MALAT1 can promote tumorigenicity and metastasis in GC by facilitating VM and angiogenesis via the VE-cadherin/β-catenin complex and ERK/MMP and FAK/paxillin signaling pathways.

IGF1/IGF1R/STAT3 signaling-inducible IFITM2 promotes gastric cancer growth and metastasis

Interferon-induced transmembrane proteins (IFITMs) are expressed in some types of cancer. However, their precise roles in tumor progression remain unclear. The present study investigated the function of IFITM2 in gastric cancer (GC) progression. A retrospective analysis of a public database and 167 GC patients revealed that IFITM2 expression was upregulated in gastric tumor samples, which was positively correlated with disease progression, more frequent postoperative recurrence, and higher mortality rate. IFITM2 knockdown decreased GC cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition in vitro. We also found that IFITM2 expression was in part induced by insulin-like growth factor (IGF) 1 via IGF1 receptor/signal transducer and activator of transcription 3 signaling. Furthermore, IFITM2 regulated interleukin-6 expression and secretion, which in turn increased IFITM2 expression. Silencing of IFITM2 expression suppressed tumor growth and lung metastasis in vivo. These results suggest that IFITM2 is a novel prognostic biomarker and regulator of GC progression.

A new mechanism of trastuzumab resistance in gastric cancer: MACC1 promotes the Warburg effect via activation of the PI3K/AKT signaling pathway

Background

Trastuzumab, a humanized antibody targeting HER2, exhibits remarkable therapeutic efficacy against HER2-positive gastric cancer. However, recurrent therapeutic resistance presents revolutionary claims. Warburg effect and AKT signaling pathway was involved in the resistance to trastuzumab. Our previous studies have demonstrated that overexpression of metastasis associated with the colon cancer 1 (MACC1) predicted poor prognosis of GC and promoted tumor cells proliferation and invasion. In this study, we found that MACC1 was significantly upregulated in trastuzumab-resistant cell lines. Besides, downregulation of MACC1 reversed this resistance.

Methods

The effect of trastuzumab and glycolysis inhibitor combination on cell viability, apoptosis, and cell metabolism was investigated in vitro using established trastuzumab-resistant GC cell lines. We assessed the impact of trastuzumab combined with oxamate on tumor growth and metabolism in an established xenograft model of HER2-positive GC cell lines.

Results

Here, we found that MACC1 was significantly upregulated in trastuzumab-resistant cell lines. Besides, downregulation of MACC1 in trastuzumab-resistant cells reversed this resistance. Overexpression of MACC1-induced trastuzumab resistance, enhanced the Warburg effect, and activated the PI3K/AKT signaling pathway, while downregulation of MACC1 presented the opposite effects. Moreover, when the PI3K/AKT signaling pathway was inhibited, the effects of MACC1 on resistance and glycolysis were diminished. Our findings indicated that MACC1 promoted the Warburg effect mainly through the PI3K/AKT signaling pathway, which further enhanced GC cells trastuzumab resistance.

Conclusions

Our results indicate that co-targeting of HER2 and the Warburg effect reversed trastuzumab resistance in vitro and in vivo, suggesting that the combination might overcome trastuzumab resistance in MACC1-overexpressed, HER2-positive GC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0302-1) contains supplementary material, which is available to authorized users.