Gene Summary

Gene:MT1G; metallothionein 1G
Aliases: MT1, MT1K
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Source:NCBIAccessed: 21 August, 2015


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 21 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 21 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (8)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MT1G (cancer-related)

Oshima H, Nakayama M, Han TS, et al.
Suppressing TGFβ signaling in regenerating epithelia in an inflammatory microenvironment is sufficient to cause invasive intestinal cancer.
Cancer Res. 2015; 75(4):766-76 [PubMed] Related Publications
Genetic alterations in the TGFβ signaling pathway in combination with oncogenic alterations lead to cancer development in the intestines. However, the mechanisms of TGFβ signaling suppression in malignant progression of intestinal tumors have not yet been fully understood. We have examined Apc(Δ716) Tgfbr2(ΔIEC) compound mutant mice that carry mutations in Apc and Tgfbr2 genes in the intestinal epithelial cells. We found inflammatory microenvironment only in the invasive intestinal adenocarcinomas but not in noninvasive benign polyps of the same mice. We thus treated simple Tgfbr2(ΔIEC) mice with dextran sodium sulfate (DSS) that causes ulcerative colitis. Importantly, these Tgfbr2(ΔIEC) mice developed invasive colon cancer associated with chronic inflammation. We also found that TGFβ signaling is suppressed in human colitis-associated colon cancer cells. In the mouse invasive tumors, macrophages infiltrated and expressed MT1-MMP, causing MMP2 activation. These results suggest that inflammatory microenvironment contributes to submucosal invasion of TGFβ signaling-repressed epithelial cells through activation of MMP2. We further found that regeneration was impaired in Tgfbr2(ΔIEC) mice for intestinal mucosa damaged by DSS treatment or X-ray irradiation, resulting in the expansion of undifferentiated epithelial cell population. Moreover, organoids of intestinal epithelial cells cultured from irradiated Tgfbr2(ΔIEC) mice formed "long crypts" in Matrigel, suggesting acquisition of an invasive phenotype into the extracellular matrix. These results, taken together, indicate that a simple genetic alteration in the TGFβ signaling pathway in the inflamed and regenerating intestinal mucosa can cause invasive intestinal tumors. Such a mechanism may play a role in the colon carcinogenesis associated with inflammatory bowel disease in humans.

Lu S, Zhu Q, Zhang Y, et al.
Dual-Functions of miR-373 and miR-520c by Differently Regulating the Activities of MMP2 and MMP9.
J Cell Physiol. 2015; 230(8):1862-70 [PubMed] Related Publications
MicroRNA-520c (miR-520c) and microRNA-373 (miR-373) are originally characterized as both oncogenes and tumor suppressors in different types of human cancers. In this study, we found that translation of mRNA of MT1-MMP, an oncogene related to tumor metastasis, was well inhibited by miR-520c and miR-373 in several types of human cancer cells. Our experimental data demonstrated that these two microRNAs inhibited the translation of mRNA of MT1-MMP and down-regulated its proteolytic enzyme activities via targeting 3'UTR of mRNA of MT1-MMP, further decreased activating proMMP2 into active MMP2 in fibrosarcoma HT1080, benign prostatic hyperplasia epithelial cell BPH-1 and glioblastoma U87GM. More interestingly, from the effects of microRNAs on cell functions, we found that cell growth were all blocked on fibronectin and type IV collagen coated plates and also in three-dimension type I collagen lattice but enhanced only in HT1080 cells on type IV collagen coated plates and in three-dimension type I collagen lattice; cell migration results showed the same effect as that of cell growth. The difference was due to up-regulating the expression of MMP9 gene by miR-520c and miR-373 in HT1080 cells but not in BPH-1 and U87GM cells. Our findings suggest that miR-520c and miR-373, which have different roles in different type of cancer via regulating the translation of mRNA of MT1-MMP and the expression of MMP9 gene, might have an important clue on clinic when selecting the therapeutic regimen and finding new drugs for intervention in different kinds of cancer.

Yi SA, Ryu HW, Lee DH, et al.
HP1β suppresses metastasis of human cancer cells by decreasing the expression and activation of MMP2.
Int J Oncol. 2014; 45(6):2541-8 [PubMed] Related Publications
Heterochromatin protein 1 (HP1) is an epigenetic modifier of gene regulation and chromatin packing via binding to trimethylated histone H3 lysine 9 (H3K9). HP1 plays an important role in gene activation as well as gene repression in heterochromatin and euchromatin. However, the role of individual HP1 proteins in human diseases remains elusive. Here, we show that HP1β negatively regulates the expression and activation of matrix metallopeptidase (MMP)2, which mediates cancer metastasis by destructing type Ⅳ collagen. Reduced HP1β expression correlates with the increased level of pro- and active-MMP2 in colon cancer cells. Consistently, HP1β knockdown (KD) increased and HP1β overexpression decreased the mRNA level of MMP2 and membrane type 1 metallopeptidase (MT1-MMP). Furthermore, cancer cells overexpressing HP1β showed impaired migratory ability, whereas HP1β‑deleted cancer cells had increased migration. HP1β negatively regulates MMP2 expression in a transcriptional level and prevents MMP2 activation through reducing the expression of MT1‑MMP. These findings shed new light on HP1β as a molecular regulator and an efficient therapeutic target of metastatic cancer.

Hsiao CC, Wang WC, Kuo WL, et al.
CD97 inhibits cell migration in human fibrosarcoma cells by modulating TIMP-2/MT1- MMP/MMP-2 activity--role of GPS autoproteolysis and functional cooperation between the N- and C-terminal fragments.
FEBS J. 2014; 281(21):4878-91 [PubMed] Related Publications
CD97 is a tumor-associated adhesion-class G-protein-coupled receptor involved in modulating cell migration. Adhesion-class G-protein-coupled receptors are characterized by proteolytic cleavage at a G-protein-coupled receptor proteolysis site (GPS) into an N-terminal fragment (NTF) and a C-terminal fragment (CTF), which remain associated noncovalently. The molecular mechanism and the role of GPS proteolysis in CD97-modulated cell migration are not completely understood. We report here that CD97 expression in HT1080 fibrosarcoma cells enhanced tissue inhibitor of metalloproteinase-2 secretion, leading to reduced membrane type 1 matrix metalloproteinase and matrix metalloproteinase 2 activities. This, in turn, impaired cell migration and invasion in vitro and lung macrometastasis in vivo. CD97 expression also upregulated the expression of integrins, promoting cell adhesion. Importantly, these cellular functions absolutely required the presence of both the NTF and the CTF of CD97, confirming functional cooperation between the two receptor subunits. CD97 gene knockdown reversed these phenotypic changes. We conclude that GPS proteolysis and the functional interplay between the NTF and the CTF are indispensible for CD97 to inhibit HT1080 cell migration by suppressing matrix metalloproteinase activity.

Frittoli E, Palamidessi A, Marighetti P, et al.
A RAB5/RAB4 recycling circuitry induces a proteolytic invasive program and promotes tumor dissemination.
J Cell Biol. 2014; 206(2):307-28 [PubMed] Free Access to Full Article Related Publications
The mechanisms by which tumor cells metastasize and the role of endocytic proteins in this process are not well understood. We report that overexpression of the GTPase RAB5A, a master regulator of endocytosis, is predictive of aggressive behavior and metastatic ability in human breast cancers. RAB5A is necessary and sufficient to promote local invasion and distant dissemination of various mammary and nonmammary tumor cell lines, and this prometastatic behavior is associated with increased intratumoral cell motility. Specifically, RAB5A is necessary for the formation of invadosomes, membrane protrusions specialized in extracellular matrix (ECM) degradation. RAB5A promotes RAB4- and RABENOSYN-5-dependent endo/exocytic cycles (EECs) of critical cargos (membrane-type 1 matrix metalloprotease [MT1-MMP] and β3 integrin) required for invadosome formation in response to motogenic stimuli. This trafficking circuitry is necessary for spatially localized hepatocyte growth factor (HGF)/MET signaling that drives invasive, proteolysis-dependent chemotaxis in vitro and for conversion of ductal carcinoma in situ to invasive ductal carcinoma in vivo. Thus, RAB5A/RAB4 EECs promote tumor dissemination by controlling a proteolytic, mesenchymal invasive program.

Zou J, Xu L, Ju Y, et al.
Cholesterol depletion induces ANTXR2-dependent activation of MMP-2 via ERK1/2 phosphorylation in neuroglioma U251 cell.
Biochem Biophys Res Commun. 2014; 452(1):186-90 [PubMed] Related Publications
Cholesterol is a critical component of lipid rafts implicated in regulating multiple signal transduction. The anthrax toxin receptor 2 (ANTXR2) is a type I membrane protein acting as the second receptor for the anthrax toxin. In this study, we first investigated the association between cholesterol and ANTXR2. We provided the evidence that cholesterol depletion by methyl-beta-cyclodextrin (MβCD) promoted ANTXR2 expression in U251 neuroglioma cell, which was reversed by cholesterol supplement. MβCD-induced ANTXR2 up-regulation contributed to ERK1/2 phosphorylation, which was responsible for MT1-MMP and MMP-2 activation. Our data suggested that cellular cholesterol regulated ANTXR2-dependent activation of MMP-2 via ERK1/2 phosphorylation in neuroglioma U251 cell.

Mortus JR, Zhang Y, Hughes DP
Developmental pathways hijacked by osteosarcoma.
Adv Exp Med Biol. 2014; 804:93-118 [PubMed] Related Publications
Cancer of any type often can be described by an arrest, alteration or disruption in the normal development of a tissue or organ, and understanding of the normal counterpart's development can aid in understanding the malignant state. This is certainly true for osteosarcoma and the normal developmental pathways that guide osteoblast development that are changed in the genesis of osteogenic sarcoma. A carefully regulated crescendo-decrescendo expression of RUNX2 accompanies the transition from mesenchymal stem cell to immature osteoblast to mature osteoblast. This pivotal role is controlled by several pathways, including bone morphogenic protein (BMP), Wnt/β-catenin, fibroblast growth factor (FGF), and protein kinase C (PKC). The HIPPO pathway and its downstream target YAP help to regulate proliferation of immature osteoblasts and their maturation into non-proliferating mature osteoblasts. This pathway also helps regulate expression of the mature osteoblast protein osteocalcin. YAP also regulates expression of MT1-MMP, a membrane-bound matrix metalloprotease responsible for remodeling the extracellular matrix surrounding the osteoblasts. YAP, in turn, can be regulated by the ERBB family protein Her-4. Osteosarcoma may be thought of as a cell held at the immature osteoblast stage, retaining some of the characteristics of that developmental stage. Disruptions of several of these pathways have been described in osteosarcoma, including BMP, Wnt/b-catenin, RUNX2, HIPPO/YAP, and Her-4. Further, PKC can be activated by several receptor tyrosine kinases implicated in osteosarcoma, including the ERBB family (EGFR, Her-2 and Her-4 in osteosarcoma), IGF1R, FGF, and others. Understanding these functions may aid in the understanding the mechanisms underpinning clinical observations in osteosarcoma, including both the lytic and blastic phenotypes of tumors, the invasiveness of the disease, and the tendency for treated tumors to ossify rather than shrink. Through a better understanding of the relationship between normal osteoblast development and osteosarcoma, we may gain insights into novel therapeutic avenues and improved outcomes.

Umbreit C, Aderhold C, Faber A, et al.
Imatinib-associated matrix metalloproteinase suppression in p16-positive squamous cell carcinoma compared to HPV-negative HNSCC cells in vitro.
Oncol Rep. 2014; 32(2):668-76 [PubMed] Related Publications
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer worldwide. The growth and invasion of HNSCC are strongly influenced by the extracellular matrix (ECM), which is modified by matrix metalloproteinases (MMPs). The MMP family is still relevant to cancer research, as it promotes malignant transformation, cell proliferation and modulation of angiogenesis even in the early stages of cancer. The proteolytic processing of bioactive molecules by MMP-14 (MT1-MMP) causes severe abnormalities in connective tissue, defective angiogenesis and premature death. MMP-2 (gelatinase A) and MMP-14 also play a role in degradation of basement membrane and cell carcinoma invasion. Imatinib blocks the PTK receptor c-kit and forestalls its PTK activity. The aim of the present study was to investigate the expression pattern of MMP-14 and MMP-2 in human papilloma virus (HPV)-negative and p16-positive SCC and to evaluate the chemosensitivity of the tumour cells to the chemotherapeutic agents, imatinib and 5-fluorouracil (5-FU). We incubated the SCC cell lines with imatinib (18 and 30 µmol/ml) and 5-FU (1 and 5 µmol/ml) and detected MMP-14 and MMP-2 by immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) after 48, 72, 120, 192 and 240 h. We detected expression of MMP-2 and MMP-14 in all incubated tumour cell lines. With imatinib in particular, we found a reliable trend towards decreased MMP-2 and MMP-14 expression levels in p16-positive and p16-negative SCC tumour cell lines in addition to an induced apoptotic effect. We found statistically significant imatinib-induced suppression of MMP-2- and MMP-14, dependent on the incubation time and the cell line. We detected a significant suppression of MMP-2 and MMP-14 especially in p16-negative HNSCC14C cells after prolonged treatment time with imatinib. Dose escalation of imatinib and 5-FU had no statistically significant effect on the expression of MMP-2 or MMP-14. The p16-positive SCC cells exhibited higher expression of total protein. We detected a significant suppression of MMP-2 and MMP-14 in all the incubated SCC cell lines, partially after treatment with imatinib. We found higher suppression of MMP-2 in the CERV196 cells after incubation with imatinib. We detected a reliable trend towards increased chemosensitivity of p16-positive tumour cells in vitro after treatment with imatinib. Extended studies and clinical trials are needed to further investigate these findings in HPV-associated HNSCC.

Yang Y, Bai ZG, Yin J, et al.
Role of c-Src activity in the regulation of gastric cancer cell migration.
Oncol Rep. 2014; 32(1):45-9 [PubMed] Free Access to Full Article Related Publications
Gastric cancer is associated with increased migration and invasion. In the present study, we explored the role of c-Src in gastric cancer cell migration and invasion. BGC-823 gastric cancer cells were used to investigate migration following treatment of these cells with the c-Src inhibitors, PP2 and SU6656. Migration and invasion were analyzed by wound healing and Transwell assays. Western blot analysis was used to detect the expression of MT1-MMP and VEGF-C, while the activity of MMP2 and MMP9 was monitored with gelatin zymography assay. Immunoprecipitation was used to detect interactions among furin, pro-MT1-MMP and pro-VEGF-C. MT1-MMP and VEGF-C expression levels were inhibited by PP2 and SU6656 treatment, in accordance with decreased c-Src activity. Similarly, the zymography assay demonstrated that the activity of MMP2 and MMP9 was decreased following PP2 or SU6656 treatment. Blockade of c-Src also inhibited the invasive and migratory capacity of BGC-823 cells. Notably, c-Src interacted with furin in vivo, while interactions between furin and its substrates, pro-MT1-MMP and pro-VEGF-C, were decreased by c-Src inhibitors. In conclusion, the interaction among furin and pro-MT1-MMP or pro-VEGF-C or other tumor-associated precursor enzymes can be regulated by c-Src activity, thus reducing or changing the expression of these enzymes in order to reduce the development of gastric cancer, invasion and metastasis.

Ellina MI, Bouris P, Aletras AJ, et al.
EGFR and HER2 exert distinct roles on colon cancer cell functional properties and expression of matrix macromolecules.
Biochim Biophys Acta. 2014; 1840(8):2651-61 [PubMed] Related Publications
BACKGROUND: ErbB receptors, EGFR and HER2, have been implicated in the development and progression of colon cancer. Several intracellular pathways are mediated upon activation of EGFR and/or HER2 by EGF. However, there are limited data regarding the EGF-mediated signaling affecting functional cell properties and the expression of extracellular matrix macromolecules implicated in cancer progression.
METHODS: Functional assays, such as cell proliferation, transwell invasion assay and migration were performed to evaluate the impact of EGFR/HER2 in constitutive and EGF-treated Caco-2 cells. Signaling pathways were evaluated using specific intracellular inhibitors. Western blot was also utilized to examine the phosphorylation levels of ERK1/2. Real time PCR was performed to evaluate gene expression of matrix macromolecules.
RESULTS: EGF increases cell proliferation, invasion and migration and importantly, EGF mediates overexpression of EGFR and downregulation of HER2. The EGF-EGFR axis is the main pathway affecting colon cancer's invasive potential, proliferative and migratory ability. Intracellular pathways (PI3K-Akt, MEK1/2-Erk and JAK-STAT) are all implicated in the migratory profile. Notably, MT1- and MT2-MMP as well as TIMP-2 are downregulated, whereas uPA is upregulated via an EGF-EGFR network. The EGF-EGFR axis is also implicated in the expression of syndecan-4 and TIMP-1. However, glypican-1 upregulation by EGF is mainly mediated via HER2.
CONCLUSIONS AND GENERAL SIGNIFICANCE: The obtained data highlight the crucial importance of EGF on the expression of both receptors and on the EGF-EGFR/HER2 signaling network, reveal the distinct roles of EGFR and HER2 on expression of matrix macromolecules and open a new area in designing novel agents in targeting colon cancer. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Augoff K, Hryniewicz-Jankowska A, Tabola R, et al.
Upregulated expression and activation of membrane‑associated proteases in esophageal squamous cell carcinoma.
Oncol Rep. 2014; 31(6):2820-6 [PubMed] Related Publications
To better understand the role of membrane-associated proteolytic systems in the development of esophageal cancer, we studied the expression of two serine proteases, fibroblast activation protein-α (FAP-α) and dipeptidyl peptidase IV (DPPIV) and three metalloproteinases, matrix metalloproteinase (MMP)-2, MMP-9 and MT1-MMP in 24 primary esophageal squamous cell carcinoma (ESCC) tissues and paired non-cancer tissues. Using reverse-transcription PCR, western blotting and zymography, we showed that both serine proteases and all three metalloproteinases were highly altered in ESCC. A positive correlation between the expression of FAP-α and DPPIV and the activity of both gelatinases was found. This may indicate that these proteolytic systems are tightly linked to each other and collectively are involved in the process of ECM degradation that facilitates cancer cell invasion and metastasis.

Ji XF, Fan YC, Gao S, et al.
MT1M and MT1G promoter methylation as biomarkers for hepatocellular carcinoma.
World J Gastroenterol. 2014; 20(16):4723-9 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate the potential of promoter methylation of two tumor suppressor genes (TSGs) as biomarkers for hepatocellular carcinoma (HCC).
METHODS: A total of 189 subjects were included in this retrospective cohort, which contained 121 HCC patients without any history of curative treatment, 37 patients with chronic hepatitis B (CHB), and 31 normal controls (NCs). DNA samples were extracted from 400 μL of serum of each subject and then modified using bisulfite treatment. Methylation of the promoters of the TSGs (metallothionein 1M, MT1M; and metallothionein 1G, MT1G) was determined using methylation-specific polymerase chain reaction. The diagnostic value of combined MT1M and MT1G promoter methylation was evaluated using the area under the receiver operating characteristic curves.
RESULTS: Our results indicated that the methylation status of serum MT1M (48.8%, 59/121) and MT1G (70.2%, 85/121) promoters in the HCC group was significantly higher than that in the CHB group (MT1M 5.4%, 2/37, P < 0.001; MT1G 16.2%, 6/37, P < 0.001) and NC group (MT1M 6.5%, 2/31, P < 0.001; MT1G 12.9%, 4/27, P < 0.001). Aberrant serum MT1M promoter methylation gave higher specificity to discriminate HCC from CHB (94.6%) and NCs (93.5%), whereas combined methylation of serum MT1M and MT1G promoters showed higher diagnostic sensitivity (90.9%), suggesting that they are potential markers for noninvasive detection of HCC. Furthermore, MT1M promoter methylation was positively correlated with tumor size (rs = 0.321, P < 0.001), and HCC patients with both MT1M and MT1G promoter methylation tended to show a higher incidence of vascular invasion or metastasis (P = 0.018).
CONCLUSION: MT1M and MT1G promoter methylation may be used as serum biomarkers for noninvasive detection of HCC.

Hong IK, Byun HJ, Lee J, et al.
The tetraspanin CD81 protein increases melanoma cell motility by up-regulating metalloproteinase MT1-MMP expression through the pro-oncogenic Akt-dependent Sp1 activation signaling pathways.
J Biol Chem. 2014; 289(22):15691-704 [PubMed] Free Access to Full Article Related Publications
Despite the importance of multiple tetraspanin proteins in cancer invasion and metastasis, little is known about the role and significance of tetraspanin CD81 in these processes. In the present study, we examined CD81 effects on melanoma cell invasiveness and metastasis. Transfection of CD81 into melanoma cells lacking endogenous CD81 expression significantly enhanced the migrating, invasive, and metastatic abilities of melanoma cells. Interestingly, membrane type 1 matrix metalloproteinase (MT1-MMP) expression was found in CD81-expressing melanoma cells but not in CD81-deficient cells. siRNA knockdown of CD81 in melanoma cells with endogenous CD81 demonstrated decreased MT1-MMP levels and cell motility. Notably, CD81-induced cell migration was abrogated by antibody blocking and siRNA knockdown of MT1-MMP, indicating that MT1-MMP is responsible for CD81-stimulated melanoma cell migration. Promoter analysis revealed an essential role of the Sp1 transcription factor in CD81-induced MT1-MMP transcription. We also demonstrate that the Sp1-activating Akt pathway is involved in adhesion-dependent CD81 signaling to induce MT1-MMP expression and cell motility. Importantly, human skin cancer tissue specimens displayed a positive correlation of CD81 with MT1-MMP expression levels and a close association of CD81 with malignant melanomas. Taken together, these results strongly suggest that CD81 stimulates melanoma cell motility by inducing MT1-MMP expression through the Akt-dependent Sp1 activation signaling pathway, leading to increased melanoma invasion and metastasis.

Arriaga JM, Greco A, Mordoh J, Bianchini M
Metallothionein 1G and zinc sensitize human colorectal cancer cells to chemotherapy.
Mol Cancer Ther. 2014; 13(5):1369-81 [PubMed] Related Publications
Metallothioneins (MT) are a family of low molecular weight proteins that are silenced during colorectal cancer progression, mainly through epigenetic mechanisms, and this loss is associated with poor survival. In this article, we show that overexpression of the MT1G isoform sensitizes colorectal cell lines to the chemotherapeutic agents oxaliplatin (OXA) and 5-fluorouracil (5-FU), in part through enhancing p53 and repressing NF-κB activity. Despite being silenced, MTs can be reinduced by histone deacetylase inhibitors such as trichostatin A and sodium butyrate. In fact, this induction contributes to the cytotoxicity of these agents, given that silencing of MTs by siRNAs reduces their growth-inhibitory activities. Zinc ions also potently enhance MT expression and are cytotoxic to cancer cells. We show for the first time that OXA and 5-FU induce higher levels of intracellular labile zinc, as measured using the fluorescent probe FLUOZIN-3, and that such zinc contributes to the activation of p53 and repression of NF-κB. Addition of zinc enhanced growth inhibition by OXA and 5-FU, and was also capable of resensitizing 5-FU-resistant cell lines to levels comparable with sensitive cell lines. This effect was MT independent because silencing MTs did not affect zinc cytotoxicity. In conclusion, we show that MT induction and zinc administration are novel strategies to sensitize colorectal cancer cells to presently utilized chemotherapeutic agents.

Zhang JT, Sun W, Zhang WZ, et al.
Norcantharidin inhibits tumor growth and vasculogenic mimicry of human gallbladder carcinomas by suppression of the PI3-K/MMPs/Ln-5γ2 signaling pathway.
BMC Cancer. 2014; 14:193 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Vasculogenic mimicry (VM) is a novel tumor blood supply in some highly aggressive malignant tumors. Recently, we reported VM existed in gallbladder carcinomas (GBCs) and the formation of the special passage through the activation of the PI3K/MMPs/Ln-5γ2 signaling pathway. GBC is a highly aggressive malignant tumor with disappointing treatments and a poor prognosis. Norcantharidin (NCTD) has shown to have multiple antitumor activities against GBCs, etc; however the exact mechanism is not thoroughly elucidated. In this study, we firstly investigated the anti-VM activity of NCTD as a VM inhibitor for GBCs and its underlying mechanisms.
METHODS: In vitro and in vivo experiments to determine the effects of NCTD on proliferation, invasion, migration, VM formation, hemodynamic and tumor growth of GBC-SD cells and xenografts were respectively done by proliferation, invasion, migration assays, H&E staining and CD31-PAS double stainings, optic/electron microscopy, tumor assay, and dynamic micro-MRA. Further, immunohistochemistry, immunofluorescence, Western blotting and RT-PCR were respectively used to examine expression of VM signaling-related markers PI3-K, MMP-2, MT1-MMP and Ln-5γ2 in GBC-SD cells and xenografts in vitro and in vivo.
RESULTS: After treatment with NCTD, proliferation, invasion, migration of GBC-SD cells were inhibited; GBC-SD cells and xenografts were unable to form VM-like structures; tumor center-VM region of the xenografts exhibited a decreased signal in intensity; then cell or xenograft growth was inhibited. Whereas all of untreated GBC-SD cells and xenografts formed VM-like structures with the same conditions; the xenograft center-VM region exhibited a gradually increased signal; and facilitated cell or xenograft growth. Furthermore, expression of MMP-2 and MT1-MMP products from sections/supernates of 3-D matrices and the xenografts, and expression of PI3-K, MMP-2, MM1-MMP and Ln-5γ2 proteins/mRNAs of the xenografts were all decreased in NCTD or TIMP-2 group; (all P < 0.01, vs. control group); NCTD down-regulated expression of these VM signaling-related markers in vitro and in vivo.
CONCLUSIONS: NCTD inhibited tumor growth and VM of human GBCs in vitro and in vivo by suppression of the PI3-K/MMPs/Ln-5γ2 signaling pathway. It is firstly concluded that NCTD may be a potential anti-VM agent for human GBCs.

Golubkov VS, Strongin AY
Downstream signaling and genome-wide regulatory effects of PTK7 pseudokinase and its proteolytic fragments in cancer cells.
Cell Commun Signal. 2014; 12:15 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The full-length membrane protein tyrosine kinase 7 (PTK7) pseudokinase, an important component of the planar cell polarity and the Wnt canonical and non-canonical pathways, is a subject of step-wise proteolysis in cells and tissues. The proteolysis of PTK7 involves membrane type-matrix metalloproteinase (MT1-MMP), members of the Disintegrin Domain and Metalloproteinase (ADAM) family, and γ-secretase. This multi-step proteolysis results in the generation of the digest fragments of PTK7. These fragments may be either liberated into the extracellular milieu or retained on the plasma membrane or released into the cytoplasm and then transported into the nucleus.
RESULTS: We employed the genome-wide transcriptional and kinome array analyses to determine the role of the full-length membrane PTK7 and its proteolytic fragments in the downstream regulatory mechanisms, with an emphasis on the cell migration-related genes and proteins. Using fibrosarcoma HT1080 cells stably expressing PTK7 and its mutant and truncated species, the structure of which corresponded to the major PTK7 digest fragments, we demonstrated that the full-length membrane 1-1070 PTK7, the N-terminal 1-694 soluble ectodomain fragment, and the C-terminal 622-1070 and 726-1070 fragments differentially regulate multiple genes and signaling pathways in our highly invasive cancer cell model. Immunoblotting of the selected proteins were used to validate the results of our high throughput assays.
CONCLUSIONS: Our results suggest that PTK7 levels need to be tightly controlled to enable migration and that the anti-migratory effect of the full-length membrane PTK7 is linked to the down-regulation of multiple migration-related genes and to the activation of the Akt and c-Jun pathway. In turn, the C-terminal fragments of PTK7 act predominantly via the RAS-ERK and CREB/ATF1 pathway and through the up-regulation of cadherin-11. In general, our data correlate well with the distinct functionality of the full-length receptor tyrosine kinases and their respective intracellular domain (ICD) proteolytic fragments.

Gialeli Ch, Viola M, Barbouri D, et al.
Dynamic interplay between breast cancer cells and normal endothelium mediates the expression of matrix macromolecules, proteasome activity and functional properties of endothelial cells.
Biochim Biophys Acta. 2014; 1840(8):2549-59 [PubMed] Related Publications
BACKGROUND: Breast cancer-endothelium interactions provide regulatory signals facilitating tumor progression. The endothelial cells have so far been mainly viewed in the context of tumor perfusion and relatively little is known regarding the effects of such paracrine interactions on the expression of extracellular matrix (ECM), proteasome activity and properties of endothelial cells.
METHODS: To address the effects of breast cancer cell (BCC) lines MDA-MB-231 and MCF-7 on the endothelial cells, two cell culture models were utilized; one involves endothelial cell culture in the presence of BCCs-derived conditioned media (CM) and the other co-culture of both cell populations in a Transwell system. Real-time PCR was utilized to evaluate gene expression, an immunofluorescence assay for proteasome activity, and functional assays (migration, adhesion and invasion) and immunofluorescence microscopy for cell integrity and properties.
RESULTS: BCC-CM decreases the cell migration of HUVEC. Adhesion and invasion of BCCs are favored by HUVEC and HUVEC-CM. HA levels and the expression of CD44 and HA synthase-2 by HUVEC are substantially upregulated in both cell culture approaches. Adhesion molecules, ICAM-1 and VCAM-1, are also highly upregulated, whereas MT1-MMP and MMP-2 expressions are significantly downregulated in both culture systems. Notably, the expression and activity of the proteasome β5 subunit are increased, especially by the action of MDA-MB-231-CM on HUVEC.
CONCLUSIONS AND GENERAL SIGNIFICANCE: BCCs significantly alter the expression of matrix macromolecules, proteasome activity and functional properties of endothelial cells. Deep understanding of such paracrine interactions will help to design novel drugs targeting breast cancer at the ECM level. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Ma J, Tang X, Wong P, et al.
Noncanonical activation of Notch1 protein by membrane type 1 matrix metalloproteinase (MT1-MMP) controls melanoma cell proliferation.
J Biol Chem. 2014; 289(12):8442-9 [PubMed] Free Access to Full Article Related Publications
Notch1 is an evolutionarily conserved signaling molecule required for stem cell maintenance that is inappropriately reactivated in several cancers. We have previously shown that melanomas reactivate Notch1 and require its function for growth and survival. However, no Notch1-activating mutations have been observed in melanoma, suggesting the involvement of other activating mechanisms. Notch1 activation requires two cleavage steps: first by a protease and then by γ-secretase, which releases the active intracellular domain (Notch1(NIC)). Interestingly, although ADAM10 and -17 are generally accepted as the proteases responsible of Notch1 cleavage, here we show that MT1-MMP, a membrane-tethered matrix metalloproteinase involved in the pathogenesis of a number of tumors, is a novel protease required for the cleavage of Notch1 in melanoma cells. We find that active Notch1 and MT1-MMP expression correlate significantly in over 70% of melanoma tumors and 80% of melanoma cell lines, whereas such correlation does not exist between Notch1(NIC) and ADAM10 or -17. Modulation of MT1-MMP expression in melanoma cells affects Notch1 cleavage, whereas MT1-MMP expression in ADAM10/17 double knock-out fibroblasts restores the processing of Notch1, indicating that MT1-MMP is sufficient to promote Notch1 activation independently of the canonical proteases. Importantly, we find that MT1-MMP interacts with Notch1 at the cell membrane, supporting a potential direct cleavage mechanism of MT1-MMP on Notch1, and that MT1-MMP-dependent activation of Notch1 sustains melanoma cell growth. Together, the data highlight a novel mechanism of activation of Notch1 in melanoma cells and identify Notch1 as a new MT1-MMP substrate that plays important biological roles in melanoma.

Eckel-Passow JE, Serie DJ, Bot BM, et al.
ANKS1B is a smoking-related molecular alteration in clear cell renal cell carcinoma.
BMC Urol. 2014; 14:14 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: An association between cigarette smoking and increased risk of clear cell renal cell carcinoma (ccRCC) has been established; however, there are limited data regarding the molecular mechanisms that underlie this association. We used a multi-stage design to identify and validate genes that are associated with smoking-related ccRCC.
METHODS: We first conducted a microarray study to compare gene expression patterns in patient-matched ccRCC and normal kidney tissues between patients with (n = 23) and without (n = 42) a history of smoking. Analyses were first stratified on obesity status (the other primary risk factor for ccRCC) and then combined and analyzed together. To identify genes where the fold change in smokers relative to non-smokers was different in tumor tissues in comparison to patient-matched normal kidney tissues, we identified Affymetrix probesets that had a significant tissue type-by-smoking status interaction pvalue. We then performed RT-PCR validation on the top eight candidate genes in an independent sample of 28 smokers and 54 non-smokers.
RESULTS: We identified 15 probesets that mapped to eight genes that had candidate associations with smoking-related ccRCC: ANKS1B, ACOT6, PPWD1, EYS, LIMCH1, CHRNA6, MT1G, and ZNF600. Using RT-PCR, we validated that expression of ANKS1B is preferentially down-regulated in smoking-related ccRCC.
CONCLUSION: We provide the first evidence that ANKS1B expression is down regulated in ccRCC tumors relative to patient-matched normal kidney tissue in smokers. Thus, ANKS1B should be explored further as a novel avenue for early detection as well as prevention of ccRCC in smokers.

Pratt J, Annabi B
Induction of autophagy biomarker BNIP3 requires a JAK2/STAT3 and MT1-MMP signaling interplay in Concanavalin-A-activated U87 glioblastoma cells.
Cell Signal. 2014; 26(5):917-24 [PubMed] Related Publications
Plant lectins have been considered as possible anti-tumor drugs because of their property to induce autophagic cell death. Given that expression of membrane type-1 matrix metalloproteinase (MT1-MMP) has been found to regulate expression of the autophagy biomarker Bcl-2/adenovirus E1B 19kDa interacting protein 3 (BNIP3), we sought to investigate possible signaling interplay mechanisms between MT1-MMP and BNIP3 in Concanavalin-A (ConA) lectin-activated U87 glioblastoma cells. ConA induced acidic vacuole organelle formation as well as BNIP3 and MT1-MMP gene and protein expressions, whereas only BNIP3 expression was dose-dependently inhibited by the JAK2 tyrosine kinase inhibitor AG490 suggesting a requirement for some STAT-mediated signaling. Gene silencing of MT1-MMP and of STAT3 abrogated ConA-induced STAT3 phosphorylation and BNIP3 expression. Correlative analysis shows that STAT3 signaling events occur downstream from MT1-MMP induction. Overexpression of a full length MT1-MMP recombinant protein led to increased BNIP3 gene and protein expressions. The cytoplasmic domain of MT1-MMP was also found necessary for transducing STAT3 phosphorylation. Among JAK1, JAK2, JAK3, and TYK2, only JAK2 gene silencing abrogated ConA's effects on MT1-MMP and BNIP3 gene and protein expressions. Our study elucidates how MT1-MMP signals autophagy, a process which could contribute to the chemoresistance phenotype in brain cancer cells.

Nakamura M, Zhang X, Mizumoto Y, et al.
Molecular characterization of CD133+ cancer stem-like cells in endometrial cancer.
Int J Oncol. 2014; 44(3):669-77 [PubMed] Related Publications
A small subset of cells with CD133 expression is thought to have increased chemoresistance and tumorigenicity, features of cancer stem cells (CSCs); the molecular mechanisms by which these properties arise remain unclear. We characterized CD133+ endometrial cancer cells based on microarray analyses of Ishikawa cells. Of the genes upregulated in CD133+ cells compared with CD133- cells, we noted several key factors involved in the aggressive behavior of cells, including ABCG2 and matrix metalloproteinase (MMP). Flow cytometric analyses identified a side-cell population (SP) with CSC features in Ishikawa cells, and they were found to be more enriched in CD133+ cells than CD133- cells. In particular, CD133+/SP cells exhibited higher proliferative and colony‑forming activity than CD133+/non-SP cells. Matrigel invasion assay revealed that CD133+ cells have enhanced invasive capacity with elevated MT1-MMP expression. siRNA‑based knockdown of MT1-MMP largely abolished the invasive capacity of CD133+ cells, but not CD133- cells due to low levels of constitutive MT1-MMP1 expression. These findings demonstrate that increased chemoresistance and tumorigenic potential of CD133+ cells are at least partly attributed to an enriched SP fraction as well as increased MMP-1 expression. These results will be of assistance in the establishment of molecular target therapy to CSCs in endometrial cancer.

Jacomasso T, Trombetta-Lima M, Sogayar MC, Winnischofer SM
Downregulation of reversion-inducing cysteine-rich protein with Kazal motifs in malignant melanoma: inverse correlation with membrane-type 1-matrix metalloproteinase and tissue inhibitor of metalloproteinase 2.
Melanoma Res. 2014; 24(1):32-9 [PubMed] Related Publications
The invasive phenotype of many tumors is associated with an imbalance between the matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs), and the membrane-anchored reversion-inducing cysteine-rich protein with Kazal motifs (RECK). RECK inhibits MMP-2, MMP-9, and MT1-MMP, and has been linked to patient survival and better prognosis in several types of tumors. However, despite the wide implication of these MMPs in melanoma establishment and progression, the role of RECK in this type of tumor is still unknown. Here, we analyzed the expression of RECK, TIMP1, TIMP2, TIMP3, MT1MMP, MMP2, and MMP9 in two publicly available melanoma microarray datasets and in a panel of human melanoma cell lines. We found that RECK is downregulated in malignant melanoma, accompanied by upregulation of MT1MMP and TIMP2. In both datasets, we observed that the group of samples displaying higher RECK levels show lower median expression levels of MT1MMP and TIMP2 and higher levels of TIMP3. When tested in a sample-wise manner, these correlations were statistically significant. Inverse correlations between RECK, MT1MMP, and TIMP2 were verified in a panel of human melanoma cell lines and in a further reduced model that includes a pair of matched primary tumor-derived and metastasis-derived cell lines. Taken together, our data indicate a consistent correlation between RECK, MT1MMP, and TIMP2 across different models of clinical samples and cell lines and suggest evidence of the potential use of this subset of genes as a gene signature for diagnosing melanoma.

Havre PA, Dang LH, Ohnuma K, et al.
CD26 expression on T-anaplastic large cell lymphoma (ALCL) line Karpas 299 is associated with increased expression of versican and MT1-MMP and enhanced adhesion.
BMC Cancer. 2013; 13:517 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: CD26/dipeptidyl peptidase IV (DPPIV) is a multifunctional membrane protein with a key role in T-cell biology and also serves as a marker of aggressive cancers, including T-cell malignancies.
METHODS: Versican expression was measured by real-time RT-PCR and Western blots. Gene silencing of versican in parental Karpas 299 cells was performed using transduction-ready viral particles. The effect of versican depletion on surface expression of MT1-MMP was monitored by flow cytometry and surface biotinylation. CD44 secretion/cleavage and ERK (1/2) activation was followed by Western blotting. Collagenase I activity was measured by a live cell assay and in vesicles using a liquid-phase assay. Adhesion to collagen I was quantified by an MTS assay.
RESULTS: Versican expression was down-regulated in CD26-depleted Karpas 299 cells compared to the parental T-ALCL Karpas 299 cells. Knock down of versican in the parental Karpas 299 cells led to decreased MT1-MMP surface expression as well as decreased CD44 expression and secretion of the cleaved form of CD44. Parental Karpas 299 cells also exhibited higher collagenase I activity and greater adhesion to collagenase I than CD26-knockdown or versican-knockdown cells. ERK activation was also highest in parental Karpas 299 cells compared to CD26-knockdown or versican-knockdown clones.
CONCLUSIONS: Our data indicate that CD26 has a key role in cell adhesion and invasion, and potentially in tumorigenesis of T-cell lines, through its association with molecules and signal transduction pathways integral to these processes.

Zhu XQ, Hu ML, Zhang F, et al.
Expression profiling based on graph-clustering approach to determine colon cancer pathway.
J Cancer Res Ther. 2013 Jul-Sep; 9(3):467-70 [PubMed] Related Publications
CONTEXT: Colorectal cancer is the second leading cause of cancer deaths worldwide. DNA microarray-based technologies allow simultaneous analysis of expression of thousands of genes.
AIM: To search for important molecular markers and pathways that hold great promise for further treatment of patients with colorectal cancer.
MATERIALS AND METHODS: Here, we performed a comprehensive gene-level assessment of colorectal cancer using 35 colorectal cancer and 24 normal samples.
RESULTS: It was shown that AURKA, MT1G, and AKAP12 had a high degree of response in colorectal cancer. Besides, we further explored the underlying molecular mechanism within these different genes.
CONCLUSIONS: The results indicated calcium signaling pathway and vascular smooth muscle contraction pathway were the two significant pathways, giving hope to provide insights into the development of novel therapeutic targets and pathways.

Fu J, Lv H, Guan H, et al.
Metallothionein 1G functions as a tumor suppressor in thyroid cancer through modulating the PI3K/Akt signaling pathway.
BMC Cancer. 2013; 13:462 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MT1G inactivation mediated by promoter methylation has been reported in thyroid cancer. However, the role of MT1G in thyroid carcinogenesis remains unclear. The aim of this study is to examine the biological functions and related molecular mechanisms of MT1G in thyroid cancer.
METHODS: Methylation-specific PCR (MSP) was performed to analyze promoter methylation of MT1G and its relationship with clinicopathological characteristics of papillary thyroid cancer (PTC) patients. Conventional and real-time quantitative RT-PCR assays were used to evaluate mRNA expression. The functions of ectopic MT1G expression were determined by cell proliferation and colony formation, cell cycle and apoptosis, as well as cell migration and invasion assays.
RESULTS: MT1G expression was frequently silenced or down-regulated in thyroid cancer cell lines, and was also significantly decreased in primary thyroid cancer tissues compared with non-malignant thyroid tissues. Promoter methylation, along with histone modification, contributes to MT1G inactivation in thyroid tumorigenesis. Moreover, our data showed that MT1G hypermethylation was significantly positively associated with lymph node metastasis in PTC patients. Importantly, restoring MT1G expression in thyroid cancer cells dramatically suppressed cell growth and invasiveness, and induced cell cycle arrest and apoptosis through inhibiting phosphorylation of Akt and Rb.
CONCLUSIONS: We have for the first time revealed that MT1G appears to be functional tumor suppressor involved in thyroid carcinogenesis mainly through modulating the phosphatidylinositol-3-kinase (PI3K)/Akt pathway and partially through regulating the activity of Rb/E2F pathway in this study.

Raudenska M, Gumulec J, Podlaha O, et al.
Metallothionein polymorphisms in pathological processes.
Metallomics. 2014; 6(1):55-68 [PubMed] Related Publications
Metallothioneins (MTs) are a class of metal-binding proteins characterized by a high cysteine content and low molecular weight. MTs play an important role in metal metabolism and protect cells against the toxic effects of radiation, alkylating agents and oxygen free radicals. The evidence that individual genetic characteristics of MTs play an important role in physiological and pathological processes associated with antioxidant defense and detoxification inspired targeted studies of genetic polymorphisms in a clinical context. In recent years, common MT polymorphisms were identified and associated with, particularly, western lifestyle diseases such as cancer, complications of atherosclerosis, and type 2 diabetes mellitus along with related complications. This review summarizes all evidence regarding MT polymorphisms of major human MTs (MT1, MT2, MT3 and MT4), their relation to pathological processes, and outlines specific applications of MTs as a set of genetic markers for certain pathologies.

Moon HJ, Finney J, Xu L, et al.
MCF-7 cells expressing nuclear associated lysyl oxidase-like 2 (LOXL2) exhibit an epithelial-to-mesenchymal transition (EMT) phenotype and are highly invasive in vitro.
J Biol Chem. 2013; 288(42):30000-8 [PubMed] Free Access to Full Article Related Publications
LOXL2 is a copper- and lysine tyrosylquinone-dependent amine oxidase that has been proposed to function both extracellularly and intracellularly to activate oncogenic signaling pathways leading to EMT and invasion of breast cancer cells. In this study, we selected MCF-7 cells that stably express forms of recombinant LOXL2 differing in their subcellular localizations and catalytic competencies. This enabled us to dissect the molecular functions of intracellular and extracellular LOXL2s and examine their contributions to breast cancer metastasis/invasion. We discovered that secreted LOXL2 (~100-kDa) is N-glycosylated at Asn-455 and Asn-644, whereas intracellular LOXL2 (~75-kDa) is nonglycosylated and N-terminally processed, and is primarily associated with the nucleus. Both forms of LOXL2 can oxidize lysine in solution. However, we found that expression of intracellular LOXL2 is more strongly associated with EMT and invasiveness than secreted LOXL2 in vitro. The results indicate that nuclear associated LOXL2 contributes to the stabilization of Snail1 transcription factor at the protein level to induce EMT and promote invasion in vitro, through repression of E-cadherin, occludin, and estrogen receptor-α, and up-regulation of vimentin, fibronectin, and MT1-MMP.

Kaewprag J, Umnajvijit W, Ngamkham J, Ponglikitmongkol M
HPV16 oncoproteins promote cervical cancer invasiveness by upregulating specific matrix metalloproteinases.
PLoS One. 2013; 8(8):e71611 [PubMed] Free Access to Full Article Related Publications
Production of matrix metalloproteinases (MMPs) for degradation of extracellular matrix is a vital step in cancer metastasis. We investigated the effects of HPV16 oncoproteins (16E6, 16E6*I and 16E7), either individually or combined, on the transcription of 7 MMPs implicated in cervical cancer invasiveness. The levels of 7 MMPs reported to be increased in cervical cancer were determined in C33A stably expressing different HPV16 oncoproteins using quantitative RT-PCR and compared with invasion ability of cell lines using in vitro invasion and wound healing assays. Overexpression of MMP-2 and MT1-MMP was detected in HPV16E6E7 expressing cells which correlated with increased cell invasion. Combination of HPV oncoproteins always showed greater effects than its individual form. Inhibition of cell invasion using a specific MMP-2 inhibitor, OA-Hy, and anti-MT1-MMP antibody confirmed that invasion in these cells was dependent on both MMP-2 and MT1-MMP expression. Depletion of HPV16E6E7 by shRNA-mediated knock-down experiments resulted in decreased MMP-2 and MT1-MMP expression levels as well as reduced invasion ability which strongly suggested specific effects of HPV oncoproteins on both MMPs and on cell invasion. Immunohistochemistry study in invasive cervical cancers confirmed the enhanced in vivo expression of these two MMPs in HPV16-infected cells. In addition, possible sites required by HPV16E6E7 on the MMP-2 and MT1-MMP promoters were investigated and PEA3 (at -552/-540 for MMP-2, -303 for MT1-MMP) and Sp1 (at -91 for MMP-2, -102 for MT1-MMP) binding sites were shown to be essential for mediating their transactivation activity. In conclusion, our study demonstrated that HPV16E6 and E7 oncoproteins cooperate in promoting cervical cancer invasiveness by specifically upregulating MMP-2 and MT1-MMP transcription in a similar manner.

Guo R, Wu G, Li H, et al.
Promoter methylation profiles between human lung adenocarcinoma multidrug resistant A549/cisplatin (A549/DDP) cells and its progenitor A549 cells.
Biol Pharm Bull. 2013; 36(8):1310-6 [PubMed] Related Publications
Although aberrant DNA methylation has been implicated in the pathophysiology of lung cancer, the role of methylation in multidrug resistance (MDR) of lung cancer has remained unclear. To investigate whether certain distinct DNA methylation pattern is associated with acquired MDR of lung adenocarcinoma, methylated-DNA immunoprecipitation-chromatin immunoprecipitation (MeDIP-ChIP) was utilised to compare the genome-wide promoter methylation of the human lung adenocarcinoma MDR A549/cisplatin (A549/DDP) cells with its progenitor A549 cells. The comparison identified 3617 genes with differentially methylated promoter, of which 1581 were hypermethylated and 2036 were hypomethylated. Then, bisulphite sequencing polymerase chain reaction (PCR) (BSP) and quantitative reverse transcription (RT)-PCR (Q-PCR) were used to validate the promoter methylation of five candidate genes and to determine whether the expression of genes was associated with the promoter methylation. BSP confirmed that the promoter methylation incidence of the hypermethylated genes, G protein-coupled receptor 56 isoform 3 (GPR56), metallothionein 1G (MT1G), and RAS association domain family gene 1 (RASSF1), was significantly higher in A549/DDP cells compared with A549 cells (p<0.001, p=0.0099, and p=0.0165), whereas no significant difference was found in that of the other two genes, CCNL2 and BAD (p=0.0594 and p=0.5546). Additionally, Q-PCR showed that the mRNA expression of the three hypermethylated genes was significantly lower in A549/DDP cells compared with A549 cells (all p<0.001). In conclusion, this study reported for the first time that a distinct promoter methylation pattern is associated with MDR of lung adenocarcinoma A549/DDP cells and suggested that GPR56, MT1G, and RASSF1 might be the potential methylation markers associated with acquired MDR of lung adenocarcinoma.

Jiang B, Li Z, Zhang W, et al.
miR-874 Inhibits cell proliferation, migration and invasion through targeting aquaporin-3 in gastric cancer.
J Gastroenterol. 2014; 49(6):1011-25 [PubMed] Related Publications
BACKGROUND: Aquaporin-3 (AQP3) is a water transporting protein which plays an oncogenic role in several malignant tumors. However, its regulatory mechanism remains elusive to date. In this study, we investigated the microRNA-mediated gene repression mechanism involved in AQP3's role.
METHODS: The potential microRNAs targeting AQP3 were searched via bioinformatic methods and identified by luciferase reporter assays, microRNA RT-PCR and western blotting. The expression patterns of miR-874 and AQP3 in human gastric cancer (GC) specimens and cell lines were determined by microRNA RT-PCR and western blotting. 5-ethynyl-2'-deoxyuridine, cell migration and invasion assays and tumorigenicity in vivo were adopted to observe the effects of miR-874 depletion or ectopic miR-874 expression on GC cell phenotypes. Cell apoptosis was evaluated by FACS and TUNEL in vitro and in vivo respectively.
RESULTS: miR-874 suppressed AQP3 expression by binding to the 3'UTR of AQP3 mRNA in GC cells. miR-874 was significantly down-regulated and reversely correlated with AQP3 protein levels in clinical samples. Analysis of the clinicopathological significance showed that miR-874 and AQP3 were closely correlated with GC characteristics. Functional analyses indicated that ectopic miR-874 expression suppressed the growth, migration, invasion and tumorigenicity of GC cells, whereas miR-874 knockdown promoted these phenotypes. Down-regulation of Bcl-2, MT1-MMP, MMP-2 and MMP-9 and upregulation of caspase-3 activity and Bax were involved in miR-874 inducing cell apoptosis, and inhibiting migration and invasion.
CONCLUSIONS: These results provide a mechanism by which AQP3 is upregulated, as well as highlight the importance of miR-874 in gastric cancer development and progression.

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