Gene Summary

Gene:STIM1; stromal interaction molecule 1
Aliases: GOK, TAM, TAM1, IMD10, STRMK, D11S4896E
Summary:This gene encodes a type 1 transmembrane protein that mediates Ca2+ influx after depletion of intracellular Ca2+ stores by gating of store-operated Ca2+ influx channels (SOCs). It is one of several genes located in the imprinted gene domain of 11p15.5, an important tumor-suppressor gene region. Alterations in this region have been associated with the Beckwith-Wiedemann syndrome, Wilms tumor, rhabdomyosarcoma, adrenocrotical carcinoma, and lung, ovarian, and breast cancer. This gene may play a role in malignancies and disease that involve this region, as well as early hematopoiesis, by mediating attachment to stromal cells. Mutations in this gene are associated with fatal classic Kaposi sarcoma, immunodeficiency due to defects in store-operated calcium entry (SOCE) in fibroblasts, ectodermal dysplasia and tubular aggregate myopathy. This gene is oriented in a head-to-tail configuration with the ribonucleotide reductase 1 gene (RRM1), with the 3' end of this gene situated 1.6 kb from the 5' end of the RRM1 gene. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, May 2013]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:stromal interaction molecule 1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Cancer Overview

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Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Latest Publications: STIM1 (cancer-related)

Alvur O, Tokgun O, Baygu Y, et al.
The triazole linked galactose substituted dicyano compound can induce autophagy in NSCLC cell lines.
Gene. 2019; 712:143935 [PubMed] Related Publications
As seen in other types of cancer, development of drug resistance in NSCLC treatment causes adverse effects on disease fighting process. Recent studies have shown that one of the drug resistance development mechanisms is that cancer cells may acquire the ability to escape from cell death. Therefore, development of anticancer drugs which have the strategy to redirect cancer cells to any cell death pathways may provide positive results for cancer treatments. Autophagy may be a target mechanism of alternative cancer treatment strategy in cases of blocked apoptosis. There is also a complex molecular link between autophagy and apoptosis, has not been fully understood yet. The dicyano compound which we used in our study caused cell death in NSCLC cell lines. When we analyzed the cells which were treated with dicyano compound by transmission electron microscope, we observed autophagosome structures. Upon this result, we investigated expression levels of autophagic proteins in the dicyano compound-treated cells by immunoblotting and observed that expression levels of autophagic proteins were increased significantly. The TUNEL assay and qRT-PCR for pro-apoptotic and anti-apoptotic gene expression, which we performed to assess apoptosis in the dicyano compound-treated cells, showed that the cell death does not occur through apoptotic pathway. We showed that the dicyano compound, which was developed in our laboratories, may play a role in molecular link between apoptosis and autophagy and may shed light on development of new anticancer treatment strategies.

Taniyama D, Taniyama K, Kuraoka K, et al.
CD204-Positive Tumor-associated Macrophages Relate to Malignant Transformation of Colorectal Adenoma.
Anticancer Res. 2019; 39(6):2767-2775 [PubMed] Related Publications
BACKGROUND/AIM: Colorectal adenoma is well known as a precursor lesion of colorectal adenocarcinoma (ADC). We recently reported the significance of CD204 (+) tumor-associated macrophages (TAMs), a vital component of the tumor microenvironment, in the carcinoma development of gastric adenoma. The aim of the present study was to clarify the roles of TAM in the malignant transformation of colorectal adenoma.
MATERIALS AND METHODS: We immunohistochemically assessed the TAM number in 88 tubular or tubulovillous adenomas that were classified into L (low-grade adenomas) or H (high-grade adenomas).
RESULTS: Larger adenoma size, higher frequency of villous structure, loss of proliferation polarity, p53 expression, larger TAM numbers and larger microvessel density (MVD) were detected in Group H than in Group L adenomas. Positive relations were observed between TAM and MVD, proliferation polarity and the expression of p53.
CONCLUSION: CD204 (+) TAM is a novel component in the malignant transformation of colorectal adenoma.

Duan Y, Luo L, Qiao C, et al.
A novel human anti-AXL monoclonal antibody attenuates tumour cell migration.
Scand J Immunol. 2019; 90(2):e12777 [PubMed] Related Publications
TAM family members (TYRO3, AXL and MERTK) play essential roles in the resolution of inflammation and in infectious diseases and cancer. AXL, a tyrosine kinase receptor, is commonly overexpressed in several solid tumours and numerous hematopoietic malignancies including acute myeloid leukaemia, acute lymphocytic leukaemia, chronic myeloid leukaemia, chronic lymphocytic leukaemia and multiple myeloma. AXL significantly promotes tumour cell migration, invasion and metastasis, as well as angiogenesis. AXL also plays an important role in inflammation and macrophage ontogeny. Recent studies have revealed that AXL contributes to leukaemic phenotypes through activation of oncogenic signalling pathways that lead to increased cell migration and proliferation. To evaluate the mechanisms underlying the role of AXL signalling in tumour metastasis, we screened a phage display library to generate a novel human monoclonal antibody, named DAXL-88, that recognizes both human and murine AXL. The concentrations of DAXL-88 required for 50% maximal binding to human and murine AXL were 0.118 and 0.164 μg/mL, respectively. Furthermore, DAXL-88 bound to human AXL with high affinity (K

Wang Z, Yip LY, Lee JHJ, et al.
Methionine is a metabolic dependency of tumor-initiating cells.
Nat Med. 2019; 25(5):825-837 [PubMed] Related Publications
Understanding cellular metabolism holds immense potential for developing new classes of therapeutics that target metabolic pathways in cancer. Metabolic pathways are altered in bulk neoplastic cells in comparison to normal tissues. However, carcinoma cells within tumors are heterogeneous, and tumor-initiating cells (TICs) are important therapeutic targets that have remained metabolically uncharacterized. To understand their metabolic alterations, we performed metabolomics and metabolite tracing analyses, which revealed that TICs have highly elevated methionine cycle activity and transmethylation rates that are driven by MAT2A. High methionine cycle activity causes methionine consumption to far outstrip its regeneration, leading to addiction to exogenous methionine. Pharmacological inhibition of the methionine cycle, even transiently, is sufficient to cripple the tumor-initiating capability of these cells. Methionine cycle flux specifically influences the epigenetic state of cancer cells and drives tumor initiation. Methionine cycle enzymes are also enriched in other tumor types, and MAT2A expression impinges upon the sensitivity of certain cancer cells to therapeutic inhibition.

Zhang Q, Mao Z, Sun J
NF-κB inhibitor, BAY11-7082, suppresses M2 tumor-associated macrophage induced EMT potential via miR-30a/NF-κB/Snail signaling in bladder cancer cells.
Gene. 2019; 710:91-97 [PubMed] Related Publications
BACKGROUND: Chronic inflammatory microenvironment has been shown to play a key role in initiating tumorigenesis and facilitating malignant progression. Primary tumors surrounded with and infiltrated by tumor-associated macrophages (TAMs) significantly promote the epithelial-to-mesenchymal transition (EMT) and distant metastasis in urothelial bladder cancer.
METHODS: In this study, we aimed to explore the potential of targeting TAMs for the treatment of malignant bladder cancer.
RESULTS: First, we found a higher number of TAMs, CD68 (pan-macrophage marker), and clever-1 (M2 macrophage marker) was associated with a higher pT category and grade in a cohort of 108 patients. In vitro assays showed that the co-culture of TAMs promoted the metastatic potential in HTB-1 and T24 by up-regulating EMT markers including Snail, VEGF and Vimentin, as well as oncogenic markers such as β-catenin and NF-κB. More importantly, M2 co-cultured HTB-1 and T24 showed an increased level of metastatic microRNA, miR-30. Silencing of miR-30 resulted in the reduced metastatic potential, migration/invasion, in association with the decreased expression of Twist1 and Vimentin. The addition of BAY11-7082 into the TAM/cancer co-culture system significantly reduced the M2 phenotype and tumorigenic properties. Coincidentally, miR-30a level was significantly lowered in the presence of BAY11-7082.
CONCLUSION: Our study demonstrated that AMs promoted metastatic potential of bladder cancer cells via promoting EMT through the increase of miR-30a. BAY11-7082 treatment suppressed both oncogenic and metastatic potential in bladder cancer cells while preventing the M2 polarization of TAMs.

Hua F, Tian Y, Gao Y, et al.
Colony‑stimulating factor 1 receptor inhibition blocks macrophage infiltration and endometrial cancer cell proliferation.
Mol Med Rep. 2019; 19(4):3139-3147 [PubMed] Free Access to Full Article Related Publications
Tumor‑associated macrophages (TAMs) promote the progression of endometrial cancer (EC), but the mechanism of TAM in EC cell proliferation remains unclear. It was found that colony stimulating factor (CSF)‑1 and CSF‑1 receptor (CSF‑1R) were highly expressed in EC tissues of patients and two EC cell lines (ECC‑1 and HEC‑1A). Using wound‑healing and chemotactic migration assays to evaluate the role of EC cells in the induction of macrophage migration, it was found that the supernatant of EC cells promoted macrophage cell line (U937) migration; however, the migration capacity of U937 weakened when CSF‑1R was blocked. Subsequently, inhibition of CSF‑1 expression in EC cells also restrained U937 migration. Additionally, blocking CSF‑1R by PLX3397 treatment in U937 cells inhibited EC cell proliferation in a co‑culture system by inhibiting the expression of proliferation‑associated proteins (Janus kinase‑1, phosphoinositide 3‑kinase, AKT, cyclin kinase 2, 4 and retinoblastoma‑associated protein). Together, these results demonstrated that CSF‑1 secreted by EC cells promoted macrophage migration; similarly, CSF‑1‑stimulated macrophages promoted EC cell proliferation. These results suggested that the interaction between CSF‑1 and its receptor served an important role in promoting macrophage infiltration and progression of EC.

Morse CB, Toukatly MN, Kilgore MR, et al.
Tumor infiltrating lymphocytes and homologous recombination deficiency are independently associated with improved survival in ovarian carcinoma.
Gynecol Oncol. 2019; 153(2):217-222 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
OBJECTIVE: The presence of tumor infiltrating lymphocytes (TIL) and defects in homologous recombination (HR) are each important prognostic factors in ovarian carcinoma (OC). We characterized the association between HR deficiency (HRD) and the presence of TILs in a cohort of OC patients and the relative contribution to overall survival.
METHODS: Patients with carcinoma of the ovary, fallopian tube, or peritoneum were prospectively enrolled. Malignant neoplasm and serum samples were collected. Immunohistochemistry for CD3+ T cells and CD68+ tumor associated macrophages (TAMs) was performed on specimens collected at primary surgery. Damaging germline and somatic mutations in genes in the HR-mediated repair (HRR) pathway were identified using BROCA sequencing. HRD was defined as a damaging mutation in one of 12 genes in the HRR pathway or promoter hypermethylation in BRCA1 or RAD51C.
RESULTS: Ninety-eight of 250 patients included in the analysis had HRD OC (39.2%). HRD OC were enriched for CD3+ TILs and CD68+ TAMs. High CD3+ TIL was present in 65.3% of HRD OC compared to 43.4% of non-HRD OC (P = 0.001). High CD68+ TAM was present in 66.3% of HRD OC compared to 50.7% of non-HRD OC (P = 0.015). Patients with HRD OC and high CD3+ TILs had the longest median overall survival compared to non-HRD OC with low CD3+ TILs (70.9 vs. 35.8 months, adjusted HR 0.38, 95% CI (0.25-0.59)).
CONCLUSIONS: Patients that have both CD3+ TILs and HRD OC are afforded the greatest improvement in overall survival. This finding may have therapeutic implications for OC patients treated with emerging immunotherapies.

Wu J, Zhang XX, Zou X, et al.
The effect of Jianpi Yangzheng Xiaozheng Decoction and its components on gastric cancer.
J Ethnopharmacol. 2019; 235:56-64 [PubMed] Related Publications
ETHNOPHARMACOLOGICAL RELEVANCE: Jianpi Yangzheng Xiaozheng Decoction (JPYZXZ) is an empirical compound prescription based on the theory of traditional Chinese medicine. JPYZXZ, which is "Qi-invigorating, spleen-strengthening and stasis-removing," can improve the quality of life of gastric cancer patients and prolong their survival; however, the exact mechanism underlying the antitumor effects of this compound is still not clear.
AIM OF THE STUDY: The aim of this study is to clearly define the effect of JPYZXZ and its components, Jianpi Yangzheng Decoction (JPYZ) and Xiao Zheng San Jie Decoction (XZSJ), on inhibiting the progression of gastric cancer.
MATERIALS AND METHODS: The effect of JPYZXZ and its components on the motility of gastric cancer MGC-803 cells was measured by MTT, adhesion, transwell assays and wound-healing assays. JPYZXZ, JPYZ and XZSJ were administered to 615 mice with gastric cancer xenografts, and their effect on the inhibition of subcutaneous transplantation was analyzed. THP-1 monocyte cells were used to establish tumor-associated macrophage (TAM) models. The polarized state of the TAMs was detected by Flow Cytometry, ELISA and Immunohistochemistry. The mRNA and protein expression of tumor epithelial-mesenchymal transition (EMT) and TAM-related genes was determined by Real-time PCR and Western Blot, respectively.
RESULTS: We determined that both JPYZXZ and its components inhibited the progress of gastric cancer in vitro, and JPYZXZ was clearly more effective than JPYZ or XZSJ. The in vivo results demonstrated that the JPYZXZ and XZSJ group exhibited a significant decrease in the tumor weight compared to the control group. Further analysis indicated that JPYZXZ was more active than JPYZ or XZSJ in inhibiting the gastric cancer EMT transformation both in vivo and in vitro. However, JPYZ was more effective compared with JPYZXZ for inducing the phenotypic change in macrophages from M2 to M1.
CONCLUSIONS: Our results demonstrate that both JPYZXZ and its components prevent the progress of gastric cancer. JPYZXZ inhibits the gastric cancer EMT more effectively than JPYZ and XZSJ, but JPYZ primarily works to regulate the phenotypic change in macrophages from M2 to M1.

Wang R, Liu Y, Liu L, et al.
Tumor cells induce LAMP2a expression in tumor-associated macrophage for cancer progression.
EBioMedicine. 2019; 40:118-134 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
BACKGROUND: Tumor cells benefit from tumor-associated macrophages (TAMs) promoting tumor growth and modulating functions of other cells in tumor microenvironment (TME). However, how tumor cells regulate the property of TAMs during tumor invasion remains to be defined.
METHODS: Mouse tumor models and cancer patients' samples were analyzed to determine LAMP2a expression in TAMs. In vitro mouse primary macrophages were used to assess LAMP2a-modulated macrophage activation, and to verify LAMP2a's target proteins. The effect of LAMP2a-knockdown on tumor progression and TME maintaining was determined by using mouse tumor models.
FINDINGS: Lysosome associated membrane protein type 2A (LAMP2a) is upregulated in TAMs by tumor cells and important for tumor progression. LAMP2a expression in TAMs, but not in tumor cells, is associated with poor prognosis in breast cancer. LAMP2a inactivation induced by either shRNA or CRISPR/Cas9 prevents TAMs activation and tumor growth. LAMP2a degrades PRDX1 (peroxiredoxin 1) and CRTC1 (CREB-regulated transcription coactivator 1) to promote macrophage pro-tumorigenic activation.
INTERPRETATION: Our study suggests that tumor cells utilize LAMP2a-PRDX1/CRTC1 axis to modulate TAMs activation and promote tumor growth, reveals the role of LAMP2a in macrophage study and TAM-targeting tumor immunotherapy. FUND: National Natural Science Foundation of China (No. 81602492); National Key Research and Development Program of China (No. 2016YFA0201402).

Bartneck M, Schrammen PL, Möckel D, et al.
The CCR2
Cell Mol Gastroenterol Hepatol. 2019; 7(2):371-390 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) typically arises in fibrotic or cirrhotic livers, which are characterized by pathogenic angiogenesis. Myeloid immune cells, specifically tumor-associated macrophages (TAMs), may represent potential novel therapeutic targets in HCC, complementing current ablative or immune therapies. However, the detailed functions of TAM subsets in hepatocarcinogenesis have remained obscure.
METHODS: TAM subsets were analyzed in-depth in human HCC samples and a combined fibrosis-HCC mouse model, established by i.p. injection with diethylnitrosamine after birth and repetitive carbon tetrachloride (CCl
RESULTS: We show that human CCR2
CONCLUSIONS: The HCC microenvironment in human patients and mice is characterized by functionally distinct macrophage populations, of which the CCR2

Selmin OI, Donovan MG, Skovan B, et al.
Arsenic‑induced BRCA1 CpG promoter methylation is associated with the downregulation of ERα and resistance to tamoxifen in MCF7 breast cancer cells and mouse mammary tumor xenografts.
Int J Oncol. 2019; 54(3):869-878 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
A significant percentage (~30%) of estrogen receptor‑α (ERα)‑positive tumors become refractory to endocrine therapies; however, the mechanisms responsible for this resistance remain largely unknown. Chronic exposure to arsenic through foods and contaminated water has been linked to an increased incidence of several tumors and long‑term health complications. Preclinical and population studies have indicated that arsenic exposure may interfere with endocrine regulation and increase the risk of breast tumorigenesis. In this study, we examined the effects of sodium arsenite (NaAsIII) exposure in ERα‑positive breast cancer cells in vitro and in mammary tumor xenografts. The results revealed that acute (within 4 days) and long‑term (10 days to 7 weeks) in vitro exposure to environmentally relevant doses reduced breast cancer 1 (BRCA1) and ERα expression associated with the gain of cyclin D1 (CCND1) and folate receptor 1 (FOLR1), and the loss of methylenetetrahydrofolate reductase (MTHFR) expression. Furthermore, long‑term exposure to NaAsIII induced the proliferation and compromised the response of MCF7 cells to tamoxifen (TAM). The in vitro exposure to NaAsIII induced BRCA1 CpG methylation associated with the increased recruitment of DNA methyltransferase 1 (DNMT1) and the loss of RNA polymerase II (PolII) at the BRCA1 gene. Xenografts of NaAsIII‑preconditioned MCF7 cells (MCF7NaAsIII) into the mammary fat pads of nude mice produced a larger tumor volume compared to tumors from control MCF7 cells and were more refractory to TAM in association with the reduced expression of BRCA1 and ERα, CpG hypermethylation of estrogen receptor 1 (ESR1) and BRCA1, and the increased expression of FOLR1. These cumulative data support the hypothesis that exposure to AsIII may contribute to reducing the efficacy of endocrine therapy against ERα‑positive breast tumors by hampering the expression of ERα and BRCA1 via CpG methylation, respectively of ESR1 and BRCA1.

Jung M, Mertens C, Tomat E, Brüne B
Iron as a Central Player and Promising Target in Cancer Progression.
Int J Mol Sci. 2019; 20(2) [PubMed] Article available free on PMC after 01/05/2020 Related Publications
Iron is an essential element for virtually all organisms. On the one hand, it facilitates cell proliferation and growth. On the other hand, iron may be detrimental due to its redox abilities, thereby contributing to free radical formation, which in turn may provoke oxidative stress and DNA damage. Iron also plays a crucial role in tumor progression and metastasis due to its major function in tumor cell survival and reprogramming of the tumor microenvironment. Therefore, pathways of iron acquisition, export, and storage are often perturbed in cancers, suggesting that targeting iron metabolic pathways might represent opportunities towards innovative approaches in cancer treatment. Recent evidence points to a crucial role of tumor-associated macrophages (TAMs) as a source of iron within the tumor microenvironment, implying that specifically targeting the TAM iron pool might add to the efficacy of tumor therapy. Here, we provide a brief summary of tumor cell iron metabolism and updated molecular mechanisms that regulate cellular and systemic iron homeostasis with regard to the development of cancer. Since iron adds to shaping major hallmarks of cancer, we emphasize innovative therapeutic strategies to address the iron pool of tumor cells or cells of the tumor microenvironment for the treatment of cancer.

Gerashchenko GV, Grygoruk OV, Kononenko OA, et al.
Expression pattern of genes associated with tumor microenvironment in prostate cancer.
Exp Oncol. 2018; 40(4):315-322 [PubMed] Related Publications
AIM: To assess relative expression (RE) levels of CAF-, TAM-specific, immune defense-associated genes in prostate tumors and to show correlation of RE with clinical, pathological and molecular characteristics, with the aim to define clinically significant specific alterations in a gene expression pattern.
METHODS: RE of 23 genes was analyzed by a quantitative polymerase chain reaction in 37 freshly frozen samples of prostate cancer tissues of a different Gleason score (GS) and at various tumor stages, compared with RE in 37 paired conventionally normal prostate tissue (CNT) samples and 20 samples of prostate adenomas.
RESULTS: Differences in RE were shown for 11 genes out of 23 studied, when tumor samples were compared with corresponding CNTs. 7 genes, namely ACTA2, CXCL14, CTGF, THY1, FAP, CD163, CCL17 were upregulated in tumors. 4 genes, namely CCR4, NOS2A, MSMB, IL1R1 were downregulated in tumors. 14 genes demonstrated different RE in TNA at different stages: CXCL12, CXCL14, CTGF, FAP, HIF1A, THY1, CCL17, CCL22, CCR4, CD68, CD163, NOS2A, CTLA4, IL1R1. RE changes of 9 genes - CXCL12, CXCL14, HIF1A, CCR4, CCL17, NOS2A, CTLA4, IL1R1, IL2RA - were found in tumors with different GS. Moreover, 9 genes showed differences in RE in TNA, dependently on the presence or absence of the TMPRSS2/ERG fusion and 7 genes showed differences in RE of groups with differential PTEN expression. Significant correlations were calculated between RE of 9 genes in adenocarcinomas and the stage, and GS; also, between RE of 2 genes and the fusion presence; and between RE of 4 genes and PTEN expression.
CONCLUSIONS: Several gene expression patterns were identified that correlated with the GS, stage and molecular characteristics of tumors, i.e. presence of the TMPRSS2/ERG fusion and alterations in PTEN expression. These expression patterns can be used for molecular profiling of prostate tumors, with the aim to develop personalized medicine approaches. However, the proposed profiling requires a more detailed analysis and a larger cohort of patients with prostate tumor.

Pelekanou V, Villarroel-Espindola F, Schalper KA, et al.
CD68, CD163, and matrix metalloproteinase 9 (MMP-9) co-localization in breast tumor microenvironment predicts survival differently in ER-positive and -negative cancers.
Breast Cancer Res. 2018; 20(1):154 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
BACKGROUND: The role of tumor-associated macrophages (TAMs) in the cancer immune landscape and their potential as treatment targets or modulators of response to treatment are gaining increasing interest. TAMs display high molecular and functional complexity. Therefore their objective assessment as breast cancer biomarkers is critical. The aims of this study were to objectively determine the in situ expression and significance of TAM biomarkers (CD68, CD163, and MMP-9) in breast cancer and to identify subclasses of patients who could benefit from TAM-targeting therapies.
METHODS: We measured CD68, CD163, and MMP-9 protein expression in formalin-fixed paraffin-embedded tissues of breast carcinomas represented in tissue microarray format using multiplexed quantitative immunofluorescence (QIF) in two independent Yale cohorts: cohort A-n = 398, estrogen receptor-positive (ER
RESULTS: All three macrophage markers were co-expressed, displaying higher expression in ER
CONCLUSIONS: Macrophage activity markers correlate with survival differently in ER

Huang S, Li J, Tam NL, et al.
Uridine-cytidine kinase 2 upregulation predicts poor prognosis of hepatocellular carcinoma and is associated with cancer aggressiveness.
Mol Carcinog. 2019; 58(4):603-615 [PubMed] Related Publications
Patients with advanced hepatocellular carcinoma (HCC) continue to have a dismal prognosis. Potential biomarkers to determine prognosis and select targeted therapies are urgently needed for patients with HCC. This study aimed to elucidate the role of UCK2 in HCC prognosis and tumor progression. We performed a screen of public databases to identify functional genes associated with HCC tumorigenesis, progression, and outcome. We identified uridine-cytidine kinase 2 (UCK2) as a gene of interest for further study. UCK2 promoting HCC aggressiveness was demonstrated by evaluation of clinical samples, in vitro experiments, in vivo tumorigenicity, and transcript analysis. UCK2 expression was generally elevated in HCC and was significantly correlated with poor survival and inferior clinicopathological characteristics of HCC patients. A multivariate analysis revealed that high UCK2 expression was an independent factor for poor prognosis. In HCC cell lines, UCK2 knockdown suppressed cell migration and invasion and inhibited cell proliferation, while UCK2 overexpression had an opposite effect. Animal model experiments confirmed that knockdown of UCK2 suppressed tumor growth in vivo. The bioinformatics analysis demonstrated that UCK2 might associated with metabolsim, splicesome, and adherens junction. UCK2 is highly associated with HCC malignant behavior and is a potential prognostic predictor for HCC patients in the clinic.

Liu M, Sun X, Shi S
MORC2 Enhances Tumor Growth by Promoting Angiogenesis and Tumor-Associated Macrophage Recruitment via Wnt/β-Catenin in Lung Cancer.
Cell Physiol Biochem. 2018; 51(4):1679-1694 [PubMed] Related Publications
BACKGROUND/AIMS: In this study, we aimed to investigate how MORC family CW-type zinc finger 2 (MORC2) affects tumor progression of lung cancer.
METHODS: The MORC2 level was analyzed by real-time RT-PCR and immunohistochemistry (IHC) in normal control tissues and lung cancers. LL/2 cells overexpressing MORC2 were used to study how MORC2 expression influences lung cancer progression. The effects of MORC2 on cell viability, migration and invasion were assessed by MTT assay, Western blotting, and transwell assays, respectively. Afterwards, the effects of MORC2 on the activation of the Wnt/β-catenin pathway were explored by Western blotting. The effects of MORC2 on tumor-associated macrophages (TAM) were determined by immunofluorescence (IF) staining, real-time RT-PCR and Western blotting.
RESULTS: Our results showed that MORC2 was upregulated in lung cancers relative to adjacent tissues. The results also demonstrated that MORC2 promoted lung cancer tumor growth in vivo. Additionally, MORC2 overexpression stimulated the upregulation of vascular endothelial growth factor (VEGF), driving angiogenesis. MORC2 overexpression in LL/2 also increased the amount of aldehyde dehydrogenase-1 (ALDH1) protein, indicating that MORC2 increased cancer stem cell features. We further determined that MORC2 activated Wnt/β-catenin signaling in lung cancer cells. Upregulation of macrophage-recruiting genes including VEGF and Macrophage-specific colony stimulating factor (CSF-1) recruits TAMs to the tumor site, which has the net effect of promoting additional tumor growth and metastasis.
CONCLUSION: Our data suggest that MORC2 overexpression can drive lung cancer growth by stimulating the recruitment of TAMs in addition to angiogenesis and that activation of Wnt/β-signaling may be a key pathway underlying this phenotype that is amenable to pharmacological intervention.

Basak P, Chatterjee S, Bhat V, et al.
Long Non-Coding RNA H19 Acts as an Estrogen Receptor Modulator that is Required for Endocrine Therapy Resistance in ER+ Breast Cancer Cells.
Cell Physiol Biochem. 2018; 51(4):1518-1532 [PubMed] Related Publications
BACKGROUND/AIMS: Blocking estrogen signaling with endocrine therapies (Tamoxifen or Fulverstrant) is an effective treatment for Estrogen Receptor-α positive (ER+) breast cancer tumours. Unfortunately, development of endocrine therapy resistance (ETR) is a frequent event resulting in disease relapse and decreased overall patient survival. The long noncoding RNA, H19, was previously shown to play a significant role in estrogen-induced proliferation of both normal and malignant ER+ breast epithelial cells. We hypothesized that H19 expression is also important for the proliferation and survival of ETR cells.
METHODS: Here we utilized established ETR cell models; the Tamoxifen (Tam)-resistant LCC2 and the Fulvestrant and Tam cross-resistant LCC9 cells. Gain and loss of H19 function were achieved through lentiviral transduction as well as pharmacological inhibitors of the Notch and c-Met receptor signaling pathways. The effects of altered H19 expression on cell viability and ETR were assessed using three-dimensional (3D) organoid cultures and 2D co-cultures with low passage tumour-associated fbroblasts (TAFs).
RESULTS: Here we report that treating ETR cells with Tam or Fulvestrant increases H19 expression and that it's decreased expression overcomes resistance to Tam and Fulvestrant in these cells. Interestingly, H19 expression is regulated by Notch and HGF signaling in the ETR cells and pharmacological inhibitors of Notch and c-MET signaling together significantly reverse resistance to Tam and Fulvestrant in an H19-dependent manner in these cells. Lastly, we demonstrate that H19 regulates ERα expression at the transcript and protein levels in the ETR cells and that H19 protects ERα against Fulvestrant-mediated downregulation of ERα protein. We also observed that blocking Notch and the c-MET receptor signaling also overcomes Fulvestrant and Tam resistance in 3D organoid cultures by decreasing ERα and H19 expression in the ETR cells.
CONCLUSION: In endocrine therapy resistant breast cancer cells Fulvestrant is ineffective in decreasing ERα levels. Our data suggest that in the ETR cells, H19 expression acts as an ER modulator and that its levels and subsequently ERα levels can be substantially decreased by blocking Notch and c-MET receptor signaling. Consequently, treating ETR cells with these pharmacological inhibitors helps overcome resistance to Fulvestrant and Tamoxifen.

Huang B, Luo N, Wu X, et al.
The modulatory role of low concentrations of bisphenol A on tamoxifen-induced proliferation and apoptosis in breast cancer cells.
Environ Sci Pollut Res Int. 2019; 26(3):2353-2362 [PubMed] Related Publications
Selective estrogen receptor modulators such as tamoxifen (TAM) significantly reduce the risks of developing estrogen receptor-positive (ER+) breast cancer. Low concentrations (nanomolar range) of bisphenol A (BPA) shows estrogenic effects and further promotes the proliferation of hormone-dependent breast cancer cells. However, whether or not BPA can influence TAM-treatment resistance in breast cancer has not drawn much attention. In the current study, low concentrations of BPA reduced TAM-induced cytotoxicity of MCF-7 cells, which was proved by the suppression of cell apoptosis, transition of cell cycle from G1 to S phase, and upregulation of cyclin D1 and ERα. Simultaneously, the mRNA levels of estrogen-related receptor γ (ERRγ) and its coactivators, peroxisome proliferation-activated receptor γ coactivator-1α (PGC-1α), and PGC-1β, were increased. However, the similar effects were not observed in MDA-MB-231 cells. Our results indicated that low concentrations of BPA decreased the sensitivity of TAM in MCF-7 cells rather than in MDA-MB-231 cells. These different actions likely involved the interaction of relative receptors and coactivators. This study provided a possible support that the exposure of BPA in environmental media may potentially induce TAM resistance to breast cancer treatment.

Liu H, Yang L, Qi M, Zhang J
NFAT1 enhances the effects of tumor-associated macrophages on promoting malignant melanoma growth and metastasis.
Biosci Rep. 2018; 38(6) [PubMed] Article available free on PMC after 01/05/2020 Related Publications
Tumor-associated macrophages (TAMs) play substantial roles in tumor growth, invasion, and metastasis. Nuclear factor of activated T cell (NFAT1) has been shown to promote melanoma growth and metastasis

Poles WA, Nishi EE, de Oliveira MB, et al.
Targeting the polarization of tumor-associated macrophages and modulating mir-155 expression might be a new approach to treat diffuse large B-cell lymphoma of the elderly.
Cancer Immunol Immunother. 2019; 68(2):269-282 [PubMed] Related Publications
Aging immune deterioration and Epstein-Barr (EBV) intrinsic mechanisms play an essential role in EBV-positive diffuse large B-cell lymphoma (DLBCL) of the elderly (EBV + DLBCLe) pathogenesis, through the expression of viral proteins, interaction with host molecules and epigenetic regulation, such as miR-155, required for induction of M1 phenotype of macrophages. This study aims to evaluate the relationship between macrophage polarization pattern in the tumor microenvironment and relative expression of miR-155 in EBV + DLBCLe and EBV-negative DLBCL patients. We studied 28 EBV + DLBCLe and 65 EBV-negative DLBCL patients. Tumor-associated macrophages (TAM) were evaluated by expression of CD68, CD163 and CD163/CD68 ratio (degree of M2 polarization), using tissue microarray. RNA was extracted from paraffin-embedded tumor samples for miR-155 relative expression study. We found a significantly higher CD163/CD68 ratio in EBV + DLBCLe compared to EBV-negative DLBCL. In EBV-negative DLBCL, CD163/CD68 ratio was higher among advanced-staged/high-tumor burden disease and overexpression of miR-155 was associated with decreased polarization to the M2 phenotype of macrophages. The opposite was observed in EBV + DLBCLe patients: we found a positive association between miR-155 relative expression and CD163/CD68 ratio, which was not significant after outlier exclusion. We believe that the higher CD163/CD68 ratio in this group is probably due to the presence of the EBV since it directly affects macrophage polarization towards M2 phenotype through cytokine secretion in the tumor microenvironment. Therapeutic strategies modulating miR-155 expression or preventing immuno-regulatory and pro-tumor macrophage polarization could be adjuvants in EBV + DLBCLe therapy since this entity has a rich infiltration of M2 macrophages in its tumor microenvironment.

Qu C, Ma J, Zhang Y, et al.
Estrogen receptor variant ER-α36 promotes tamoxifen agonist activity in glioblastoma cells.
Cancer Sci. 2019; 110(1):221-234 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
Glioblastoma (GBM) is a highly infiltrative and malignant primary brain tumor. Despite aggressive therapy, patients with GBM have a dismal prognosis with median survival of approximately 1 year. Tamoxifen (TAM), a selective estrogen receptor modulator (SERM), has been used to treat GBM for many years. ER-α36 is a novel variant of estrogen receptor-alpha66 (ER-α66) and can mediate cell proliferation through estrogen or anti-estrogen signaling in different cancer cells. Previously, we found that ER-α36 was highly expressed in GBM and was involved in the tamoxifen sensitivity of glioblastoma cells. However, the molecular mechanism responsible has not been well established. Here, we found that ER-α36 is highly expressed in glioblastoma specimens. We further found that ER-α36 knockdown increased sensitivity of glioblastoma U87 cells to TAM and decreased autophagy in these cells. However, ER-α36 overexpression decreased TAM sensitivity and induced autophagy. We also established TAM-resistant glioblastoma U251 cells by a long-term culture in TAM-containing medium and found that TAM-resistant cells showed a six-fold increase of ER-α36 mRNA expression and elevated basal autophagy. ER-α36 knockdown in these TAM-resistant cells restored TAM sensitivity. In addition, we recapitulated the physiologically relevant tumor microenvironment in an integrated microfluidic device, and U87 cells were treated with a gradient of TAM. We found that ER-α36 expression is consistent with autophagy protein P62 in a three-dimensional microenvironment. In summary, these results indicate that ER-α36 contributes to tamoxifen resistance in glioblastoma cells presumably through regulation of autophagy.

Xiong H, Jin X, You C
Expression of the CD59 Glycoprotein Precursor is Upregulated in an Estrogen Receptor-alpha (ER-α)-Negative and a Tamoxifen-Resistant Breast Cancer Cell Line In Vitro.
Med Sci Monit. 2018; 24:7883-7890 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
BACKGROUND Breast cancer is the most prevalent cancer and the leading cause of cancer death among women. Tamoxifen (TAM) therapy is one of the most widely and successfully used endocrine treatments for estrogen receptor α (ERα)-positive breast cancer. However, resistance to TAM has been a major challenge. In addition, the mechanisms underlying endocrine resistance remain unclear. Here, we report that CD59, a phosphatidylinositol-anchored glycoprotein, is a candidate resistant gene for TAM therapies. MATERIAL AND METHODS The breast cancer cell line MCF-7, the MCF-10A cell line, and the TAM-resistant breast cancer cell line TAMR-MCF-7 were cultured. The TAMR-MCF-7 cells were transfected with CD59 siRNA and control siRNA. Then, the CD59 glycoprotein precursor expression was detected by reverse transcription‑quantitative polymerase chain reaction and western blot analysis. Cell counting kit-8 and flow cytometry assay were performed to examine cell proliferation, cell apoptosis, and cell cycle. In addition, the expressions of Bax, Bcl2, cleaved-caspase-8, cleaved-caspase-6, cleaved-caspase-3, and cleaved-PARP were analyzed by western blot analysis in the TAMR-MCF-7 cells treated with CD59 siRNA. RESULTS In the present study, we found that the CD59 glycoprotein precursor was aberrantly upregulated in the ERα-negative breast cancer MCF-10A cells but not the MCF-7 cells. Furthermore, the CD59 glycoprotein precursor expression was elevated in the TAM-resistant breast cancer cells. Importantly, RNAi-mediated attenuation of CD59 was sufficient to rescue the resistance to TAM in the TAMR-MCF-7 cells. CONCLUSIONS In summary, our results proposed a candidate biomarker for predicting TAM resistance in ERa-positive breast cancer via targeting CD59, therefore it could be a novel therapeutic option.

Verma A, Lam YM, Leung YC, et al.
Combined use of arginase and dichloroacetate exhibits anti-proliferative effects in triple negative breast cancer cells.
J Pharm Pharmacol. 2019; 71(3):306-315 [PubMed] Related Publications
OBJECTIVES: Drug combination in cancer therapy aims to achieve synergistic therapeutic effect, reduced drug dosage, reduced drug toxicity and minimizes or delays the induction of drug resistance. In the present study, we investigated the anticancer effects of the combination of two metabolic modulators, dichloroacetate (DCA) and bacillus caldovelox arginase (BCA) (or pegyated human arginase (HA)).
METHODS: The combination treatments were evaluated in MCF-7 and MDA-MB 231 cells as well as in MDA-MB 231 breast cancer xenograft model.
KEY FINDINGS: Dichloroacetate and BCA combination exhibited anti-proliferative effects on MCF-7 cells, which were found to be synergistic. Analysis of the gene expression upon drug treatments revealed that the synergistic anti-proliferative effect on MCF-7 cells was possibly in part due to the activation of the p53 pathway. A similar synergistic anti-proliferative effect was observed in the combined use of DCA and HA on MCF-7 and MDA-MB231 cells, which was due to induction of cell cycle arrest at G2/M phase. Moreover, the combination enhanced anti-tumour activity in a MDA-MB 231 xenograft mouse model.
CONCLUSIONS: Our results suggested that dichloroacetate and arginase combination exhibited enhanced anti-cancer effects in preclinical breast cancer models which may offer an additional treatment option for breast cancer.

Jahangiri R, Jamialahmadi K, Gharib M, et al.
Expression and clinicopathological significance of DNA methyltransferase 1, 3A and 3B in tamoxifen-treated breast cancer patients.
Gene. 2019; 685:24-31 [PubMed] Related Publications
Progression of tamoxifen resistance remained as a crucial obstacle to treatment of estrogen receptor positive breast carcinoma patients. Recent studies demonstrated the importance of DNA methylation pattern on tamoxifen refractory. This study aimed to investigate the protein expression pattern and clinicopathological significance of DNA methyltransferase 1, 3A and 3B, as leading factors in regulation of DNA methylation process, in breast carcinoma patients with adjuvant tamoxifen therapy. Seventy two Formalin-Fixed Paraffin-Embedded (FFPE) breast tumor tissues of tamoxifen sensitive (TAMS) and tamoxifen resistance (TAM-R) patients were recruited for immunohistochemical experiments. DNMT1, DNMT3a, and DNMT3b expressions were observed in 86, 72.2 and 100% of tamoxifen resistance patients, respectively. Data analysis indicated that DNMTs were overexpressed in TAM-R tumors (P < 0.05). In TAM-S subgroup, DNMT1, DNMT3A and DNMT3B expression was associated with high histologic grade (P = 0.049, P = 0.01 and P = 0.02, respectively). DNMT3B expression was also correlated with lymphatic invasion (P = 0.034). In TAM-R subgroup, DNMT1 expression associated with extracapsular nodal extension (P = 0.019). DNMT3A and DNMT3B expression showed a significant association with high histologic grade (P = 0.001) and DNMT3A expression was also associated with HER-2 status (P = 0.027). Cox proportional hazard model demonstrated that overexpression of DNMT3B remained as an independent and unfavorable prognostic factor for disease free survival (P < 0.001). Taken together, these results suggest that DNMTs could be an effective factor in development of tamoxifen resistance in breast tumors.

Zhang B, Du Y, He Y, et al.
INT-HA induces M2-like macrophage differentiation of human monocytes via TLR4-miR-935 pathway.
Cancer Immunol Immunother. 2019; 68(2):189-200 [PubMed] Related Publications
As a major component of the microenvironment of solid tumors, tumor-associated macrophages (TAMs) facilitate tumor progression. Intermediate-sized hyaluronan (INT-HA) fragments have an immunological function in cell differentiation; however, their role in promoting the polarization of non-activated macrophages to an M2-like TAM phenotype has not been characterized, and the underlying mechanisms remain unclear. Here, we used a miRNA microarray to find that some miRNAs (especially miR-935) were differentially regulated in INT-HA-induced M2-like macrophages. According to RT-qPCR and Western blot, there was an association between miR-935 and C/EBPβ, that control the polarization of macrophages. Moreover, we found that INT-HA induced an M2-like phenotype via the TLR4 receptor. In our study, there was a negative correlation between plasma HA and miR-935 in monocytes from the peripheral blood of patients with solid tumors. There was also a negative correlation between miR-935 and M2-like macrophage markers in monocytes. These findings suggest that HA fragments interact with TLR4 and educate macrophage polarization to an M2-like phenotype via miR-935. Therefore, this study provides new insight into the role of miR-935 in INT-HA-induced M2-like polarization, and suggests a potential therapeutic target for antitumor treatment.

Lin J, Hou Y, Huang S, et al.
Exportin-T promotes tumor proliferation and invasion in hepatocellular carcinoma.
Mol Carcinog. 2019; 58(2):293-304 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
Exportin-T (XPOT) belongs to the RAN-GTPase exportin family that mediates export of tRNA from the nucleus to the cytoplasm. Up-regulation of XPOT indicates poor prognosis in breast cancer patients. However, the correlation between XPOT and hepatocellular carcinoma (HCC) remains unclear. Here, we found that high expression of XPOT in HCC indicated worse prognosis via bioinformatics analysis. Consistently, immunohistochemical staining of 95 pairs of tumors and adjacent normal liver tissues (ANLT) also showed up-regulation of XPOT. Small interfering (si) RNA transfection was used to down-regulate XPOT in HepG2 and 7721 cell lines. Cell Counting Kit-8 (CCK8) assays were performed to analyze cell proliferation. Cell migration and invasion were measured by scratch wound healing assays and migration assays. Subcutaneous xenograft models were using to explore the role of XPOT in tumor formation in vivo. Down-regulation of XPOT significantly inhibited tumor proliferation and invasion in vitro and vivo. Gene set enrichment analysis (GSEA) results indicated that XPOT may affect tumor progression through cell cycle and ubiquitin-mediated proteolysis. Furthermore, knockdown of XPOT caused a block in G0/G1 phase as evidenced by down-regulation of cyclin-dependent kinase 1 (CDK1), cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase 4 (CDK4), CyclinA1 (CCNA1), CyclinB1 (CCNB1), CyclinB2 (CCNB2), and CyclinE2 (CCNE2) in HCC cells. In conclusion, our findings indicate that XPOT could serve as a novel biomarker for prognoses and a potential therapeutic target for patients with HCC.

Li J, Lu M, Jin J, et al.
miR-449a Suppresses Tamoxifen Resistance in Human Breast Cancer Cells by Targeting ADAM22.
Cell Physiol Biochem. 2018; 50(1):136-149 [PubMed] Related Publications
BACKGROUND/AIMS: Most of estrogen receptor positive breast cancer patients respond well initially to endocrine therapies, but often develop resistance during treatment with selective estrogen receptor modulators (SERMs) such as tamoxifen. Altered expression and functions of microRNAs (miRNAs) have been reportedly associated with tamoxifen resistance. Thus, it is necessary to further elucidate the function and mechanism of miRNAs in tamoxifen resistance.
METHODS: Tamoxifen sensitivity was validated by using Cell Counting Kit-8 in tamoxifen-sensitive breast cancer cells (MCF-7, T47D) and tamoxifen-resistant cells (MCF-7/TAM, T47D/ TAM). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expression level of miR-449a in tamoxifen-sensitive/-resistant cells and patient serums. Dual-luciferase assay was used to identify the binding of miR-449a and predicted gene ADAM22. The expression level of ADAM22 was determined by qRT-PCR and western blotting in miR-449a +/- breast cancer cells. Subsequently, rescue experiments were carried out to identify the function of ADAM22 in miR-449a-reduced tamoxifen resistance. Finally, Gene ontology (GO) and Protein-protein interaction analyses were performed to evaluate the potential mechanisms of ADAM22 in regulating tamoxifen resistance.
RESULTS: MiR-449a levels were downregulated significantly in tamoxifen-resistant breast cancer cells when compared with their parental cells, as well as in clinical breast cancer serum samples. Overexpression of miR-449a re-sensitized the tamoxifen-resistant breast cancer cells, while inhibition of miR-449a conferred tamoxifen resistance in parental cells. Luciferase assay identified ADAM22 as a direct target gene of miR-449a. Additionally, silencing of ADAM22 could reverse tamoxifen resistance induced by miR-449a inhibition in ER-positive breast cancer cells. GO analysis results showed ADAM22 was mainly enriched in the biological processes of cell adhesion, cell differentiation, gliogenesis and so on. Protein-protein interaction analyses appeared that ADAM22 might regulate tamoxifen resistance through PPARG, LGI1, KRAS and LYN.
CONCLUSION: Decreased miR-449a causes the upregulation of ADAM22, which induces tamoxifen resistance of breast cancer cells. These results suggest that miR-449a, functioning by targeting ADAM22, contributes to the mechanisms underlying breast cancer endocrine resistance, which may provide a potential therapeutic strategy in ER-positive breast cancers.

Seyedi Z, Hashemzadeh MR, Colagar AH, Jaafari MR
Signal transducer and activator of transcription 3 downregulation in J774A.1 cell line as a model of M2 macrophages in tumor microenvironment.
J Cancer Res Ther. 2018 Jul-Sep; 14(5):1121-1125 [PubMed] Related Publications
Aim: Tumor-associated macrophages (TAMs) play a decisive role in the regulation of tumor progression by manipulating tumor oncogenesis, angiogenesis, and immune functions within tumor microenvironments. Tumor progression is frequently associated with a phenotypic switch from M1 to M2 in TAM. Activation of signal transducer and activator of transcription 3 (STAT3) in TAM lead to tumor-induced immunosuppression. STAT3 is usually constitutively activated in a variety of malignancies. Consequently, STAT3 has emerged as a promising target for cancer immunotherapy.
Materials and Methods: In this study, J774A.1 cell line which is an M2 macrophage and overexpress STAT3 was cultured in Dulbecco's Modified Eagle Medium supplemented by fetal bovine serum. Then, the STAT3 silencing was evaluated by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) using oligofectamine containing STAT3 short interfering RNA (siRNA). Oligofectamine containing STAT3 siRNA and control siRNA were added at a final concentration of 100 nM siRNA. The untransfected cells were considered as control group.
Results: The semi-quantitative RT-PCR studies showed that J774A.1 cells express a high level of STAT3. Incubation of J774A.1 cells with oligofectamine containing STAT3 siRNA knockdown the STAT3 expression significantly both in 48 and 72 h study; however, the effect was more pronounced in 72 h study.
Conclusion: The expression of STAT3 in J774A.1 cells confirmed that these cells are M2 macrophage. Moreover, silencing of STAT3 by siRNA delivery using oligofectamine delivery suggests that siRNA delivery using vehicles like nanoliposome could be a useful therapeutic agent in M2 macrophage therapy and its switch to M1 macrophages. This approach could be considered as a novel therapeutic agent for the treatment of all cancers.

Traboulsi T, El Ezzy M, Dumeaux V, et al.
Role of SUMOylation in differential ERα transcriptional repression by tamoxifen and fulvestrant in breast cancer cells.
Oncogene. 2019; 38(7):1019-1037 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
Antiestrogens (AEs) are widely used for treatment of estrogen receptor alpha (ERα)-positive breast cancer, but display variable degrees of partial agonism in estrogen target tissues and breast cancer (BC) cells. The fact that BC cells resistant to selective ER modulators (SERMs) like tamoxifen (Tam) can still be sensitive to pure AEs, also called selective ER downregulators, suggests different mechanisms of action, some of which may contribute to the more complete suppression of estrogen target genes by pure AEs. We report herein that pure AEs such as fulvestrant induce transient binding of ERα to DNA, followed by rapid release after 30-40 min without loss of nuclear localization. Loss of DNA binding preceded receptor degradation and was not prevented by proteasome inhibition. Chromatin was less accessible in the presence of fulvestrant than with estradiol or Tam as early as 20 min following treatment, suggesting that chromatin remodeling by pure AEs at ERα target regions prevents transcription in spite of receptor binding. SUMO2/3 marks were detected on chromatin at the peak of ERα binding in cells treated with pure AEs, but not SERMs. Furthermore, decreasing SUMOylation by overexpressing the deSUMOylase SENP1 significantly delayed receptor release from DNA and de-repressed expression of estrogen target genes in the presence of fulvestrant, both in ERα-expressing MCF-7 cells and in transiently transfected ER-negative SK-BR-3 cells. Finally, mutation V534E, identified in a breast metastasis resistant to hormonal therapies, prevented ERα modification and resulted in increased transcriptional activity of estrogen target genes in the presence of fulvestrant in SK-BR-3 cells. Together, our results establish a role for SUMOylation in achieving a more complete transcriptional shut-off of estrogen target genes by pure AEs vs. SERMs in BC cells.

Busonero C, Leone S, Bianchi F, Acconcia F
In silico screening for ERα down modulators identifies thioridazine as an anti-proliferative agent in primary, 4OH-tamoxifen-resistant and Y537S ERα-expressing breast cancer cells.
Cell Oncol (Dordr). 2018; 41(6):677-686 [PubMed] Related Publications
PURPOSE: Most breast cancers (BCs) express estrogen receptor α (ERα) and are treated with the endocrine therapy (ET) drugs 4OH-tamoxifen (Tam) and fulvestrant (ICI 182,780; ICI). Unfortunately, a high fraction of ET treated women relapses and becomes resistant to ET. Therefore, additional anti-BC drugs are needed. Recently, we proposed that the identification of novel anti-BC drugs can be achieved using modulation of the intracellular ERα content in BC cells as a pharmacological target. Here, we searched for Food and Drug Administration (FDA)-approved drugs that potentially modify the ERα content in BC cells.
METHODS: We screened in silico more than 60,000 compounds to identify FDA-approved drugs with a gene signature similar to that of ICI. We identified mitoxantrone and thioridazine and tested them in primary, Tam-resistant and genome-edited Y537S ERα-expressing BC cells.
RESULTS: We found that mitoxantrone and thioridazine induced ERα downmodulation and prevented MCF-7 BC cell proliferation. Interestingly, while mitoxantrone was found to be toxic for normal breast epithelial cells, thioridazine showed a preferential activity towards BC cells. Thioridazine also reduced the ERα content and prevented cell proliferation in primary, Tam-resistant and genome-edited Y537S ERα expressing BC cells.
CONCLUSIONS: We suggest that modulation of the intracellular ERα concentration in BC cells can be exploited in in silico screens to identify anti-BC drugs and uncover a re-purposing opportunity for thioridazine in the treatment of primary and metastatic ET resistant BCs.

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