Long noncoding RNA (lncRNA) metallothionein 1 J, pseudogene (MT1JP) is downregulated in triple-negative breast cancer and upregulates microRNA-138 (miR-138) to downregulate hypoxia-inducible factor-1α (HIF-1α).

Triple-negative breast cancer (TNBC) is a highly invasive subtype of breast cancer. This study explored the molecular mechanism and influences of metallothionein 1 J, pseudogene (MT1JP), microRNA-138 (miR-138), and hypoxia-inducible factor-1α (HIF-1α) on TNBC cell proliferation and migration. We confirmed TNBC cases by immunohistochemistry (IHC) staining. The expression of MT1JP in two types of tissue collected from 78 TNBC patients was detected by performing real-time quantitative fluorescence PCR (RT-qPCR). To further evaluate the relationship among MT1JP, miR-138 and HIF-1α, expression vectors of MT1JP and HIF-1α, as well as miR-138 mimic and inhibitor, were delivered into BT-549 cells. We observed that MT1JP was downregulated in TNBC. MT1JP was positively correlated with miR-138 but negatively correlated with HIF-1α in TNBC tissues. In TNBC cells, upregulation of miR-138 and downregulation of HIF-1α were observed after overexpression of MT1JP. In addition, overexpression of miR-138 resulted in downregulation of HIF-1α but did not affect the expression of MT1JP. Decreased proliferation rate of TNBC cells was observed after overexpression of MT1JP and miR-138. HIF-1α increased cell proliferation and migration. HIF-1α also suppressed the role of MT1JP and miR-138 in TNBC cell proliferation and migration. In conclusion, our findings demonstrated that MT1JP inhibited TNBC by regulating the miR-138/HIF-1α axis, indicating that MT1JP might serve as a biomarker or target for TNBC treatment.

lncRNA MT1JP-overexpression abolishes the silencing of PTEN by miR-32 in hepatocellular carcinoma.

Previous studies have shown that long non-coding RNA (lncRNA) MT1JP plays a role as a tumor suppressor in several types of cancer. The present study aimed to explore the role of MT1JP in hepatocellular carcinoma (HCC). Paired HCC and non-tumor tissues from 64 patients with HCC were subjected to RNA isolation and reverse transcription-quantitative PCR (RT-qPCR) to analyze the differential expression of MT1JP, microRNA (miR)-32 and phosphatase and tensin homolog (PTEN) in HCC. Cell transfections, followed by RT-qPCR and western blotting, were carried out to investigate the interactions among MT1JP, miR-32 and PTEN. The role of MT1JP, miR-32 and PTEN in regulating HCC cell proliferation was assessed using a Cell Counting Kit-8 assay. It was found that MT1JP was downregulated in HCC cancer tissues compared with that in non-cancer tissues. Survival analysis showed that patients with low MT1JP expression levels exhibited a significantly higher 5-year overall survival rate compared with patients with high MT1JP levels. The expression of MT1JP in HCC tissues was positively associated with PTEN and negatively associated with miR-32. Overexpression of MT1JP increased the expression levels of PTEN and decreased the expression levels of miR-32. Overexpression of miR-32 did not affect the expression of MT1JP but decreased the expression levels of PTEN and attenuated the effect of overexpression of MT1JP on the expression of PTEN. Overexpression of MT1JP and PTEN decreased the proliferation of HCC cells. Overexpression of miR-32 played an opposite role and attenuated the effects of overexpression of MT1JP. Therefore, MT1JP may upregulate PTEN by downregulating miR-32 to regulate HCC cell proliferation.

LncRNA MT1JP plays a protective role in intrahepatic cholangiocarcinoma by regulating miR-18a-5p/FBP1 axis.

BACKGROUND: Cholangiocarcinoma is a common malignant tumor of digestive system. LncRNA metallothionein 1 J, pseudogene (MT1JP) has been reported to play tumor-suppressing roles in multiple cancers. However, its effect on cholangiocarcinoma has not been evaluated. METHODS: The expression of MT1JP in intrahepatic cholangiocarcinoma specimens and paired para-carcinoma tissues were detected by real-time PCR. The overexpression plasmid and siRNA of MT1JP were transfected into intrahepatic cholangiocarcinoma cells to change the expression levels of MT1JP. CCK-8, flow cytometry and transwell assays were performed to measure proliferation, cell cycle transition, apoptosis, migration and invasion. Dual-luciferase reporter assay, real-time PCR and western blot were carried out to screen the miRNA bound by MT1JP. In addition, xenograft experiment was used to determine the tumorigenesis of cholangiocarcinoma cells in nude mice. RESULTS: MT1JP was downregulated in intrahepatic cholangiocarcinoma specimens, and its expression was related with TNM stage and lymph node metastasis. Overexpression of MT1JP inhibited proliferation, cell cycle transition, migration and invasion, and induced apoptosis in intrahepatic cholangiocarcinoma cells. The knockdown of MT1JP led to opposite results. MT1JP bound to miR-18a-5p to facilitate the expression of fructose-1,6-bisphosphatase 1 (FBP1). MiR-18a-5p was increased in intrahepatic cholangiocarcinoma samples, and its expression was negatively correlated with that of MT1JP. In addition, MT1JP also suppressed tumorigenesis in nude mice. CONCLUSIONS: MT1JP alleviated proliferation, migration and invasion, and induced apoptosis in cholangiocarcinoma cells by regulating miR-18a-5p/FBP1 axis. These findings may provide novel insights for clinical diagnosis and treatment of cholangiocarcinoma.

Long Noncoding RNA (lncRNA) MT1JP Suppresses Hepatocellular Carcinoma (HCC) in vitro.

INTRODUCTION: The purpose of this study was to evaluate the effects and mechanisms of the long noncoding RNA (lncRNA) MT1JP on hepatocellular carcinoma (HCC) in vitro. PATIENTS AND METHODS: Thirty pairs of tumor and adjacent normal tissues were collected from HCC patients. Tissue pathology and MT1JP expression were evaluated by hematoxylin and eosin staining and in situ hybridization (ISH), respectively. The correlation between MT1JP and HCC prognosis was investigated. MTT assays, cloning, flow cytometry, transwell assays, and wound-healing assays were used to evaluate the effects of MT1JP on HCC cell lines. RT-qPCR and Western blot were used to measure the relative mRNA and protein expression levels. RESULTS: The expression of MT1JP was downregulated in HCC tumor tissues compared with that in adjacent normal tissues, while the percent survival was significantly greater in the high MT1JP expression group than in the low MT1JP expression group (P=0.0238). In vitro, overexpression of MT1JP suppressed the proliferation, invasion, and migration, reduced colony cell number, increased cell apoptosis, and induced G1-phase cell cycle arrest in Bel-7402 and Huh-7 cells. Meanwhile, the mRNA and protein expression levels of RUNX3 and P21 were significantly upregulated, whereas those of MMP2 and MMP9 were significantly downregulated, in Bel-7402 and Huh-7 cells overexpressing MT1JP (all P<0.001). CONCLUSION: LncRNA MT1JP may function as a tumor suppressor in HCC. Overexpression of MT1JP suppressed HCC cell biological activities through the regulation of RUNX3.

Overexpression of lncRNA MT1JP Mediates Apoptosis and Migration of Hepatocellular Carcinoma Cells by Regulating miR-24-3p.

OBJECTIVE: This study aimed to determine the effects of the long non-coding (lnc) RNA MT1JP on the apoptosis and migration of hepatocellular carcinoma cells. PATIENTS AND METHODS: Patients with liver cancer admitted to the Second People's Hospital of Liaocheng were included in this study. We transfected hepatocellular carcinoma cells with MT1JP and miR-24-3p and assessed their expression and effects on apoptosis and migration. Correlations were verified using a dual-luciferase reporter and RNA-binding protein coimmunoprecipitation. RESULTS: The expression of MT1JP was downregulated (P < 0.05), whereas that of miR-24-3p was upregulated in liver cancer. Serum MT1JP levels were correlated with tumor size, alpha-fetoprotein (AFP), TNM stage, differentiation, and lymph node metastasis. Both MT1JP overexpression and miR-24-3p inhibition inhibited cellular proliferation and migration and increased apoptosis rates. They significantly downregulated expression of the cell migration-associated proteins matrix metalloproteinase -2, -9 (MMP-2, MMP-9) (P < 0.05). They upregulated the expression of Bcl-2-related X protein (Bax) and cysteinyl aspartate-specific proteinases (Caspase-3 and -9) proteins that are involved in apoptosis. They decreased expression of B-cell lymphoma/leukemia-2 (Bcl-2; P < 0.05). A target relationship between MT1JP and miR-24-3p was identified using dual-luciferase gene reporter assays and RNA-binding protein coimmunoprecipitations. MT1JP overexpression significantly downregulated miR-24-3p expression (P < 0.05). MT1JP and miR-24-3p expression were negatively correlated in liver cancer tissues (r = -0.561, P < 0.001; Pearson χ2 tests). Rescue experiments showed that upregulating miR-24-3p expression could counteract MT1JP overexpression in hepatocellular carcinoma cells. CONCLUSION: MT1JP, even when expressed at low levels, participates in the proliferation, apoptosis, and migration of liver cancer cells by regulating miR-24-3p.

lncRNA MT1JP Suppresses Biological Activities of Breast Cancer Cells in vitro and in vivo by Regulating the miRNA-214/RUNX3 Axis.

INTRODUCTION: The purpose of our research was to evaluate MT1JP in breast cancer. MATERIAL AND METHODS: For clinical purpose, tissues were collected, and a correlation analysis ofMT1JP and miRNA-214 gene expressions was conducted. Using an in vitro study, MDA-MB-231 and MCF-7 cell lines were used as research objects in our research. Colony, flow cytometry, TUNEL, transwell, adhesion and wound healing assay were used to discuss the biological activities of the cells. In an in vivo study, tumor weight and volume were measured, and cell apoptosis was measured by TUNEL assay. The relative mechanism's proteins were evaluated by Western blotting or immunohistochemistry assay. RESULTS: Compared with adjacent tissues, MT1JP and miRNA-214 gene expressions were significantly different (P<0.001, respectively). By in vitro and in vivo studies, the biological activities of the cells were significantly decreased in MDA-MB-231 and MCF-7 cell lines with MT1JP overexpression. The relative mechanism was correlated with miRNA-214/RUNX3 axis. CONCLUSION: The overexpression of MT1JP suppresses the biological activities of breast cancer cells by regulation miRNA-214/RUNX3 axis in vitro and vivo study.

Long Noncoding MT1JP Enhanced the Inhibitory Effects of miR-646 on FGF2 in Osteosarcoma.

Background: It has been reported that long noncoding RNA (lncRNA) MT1JP played a tumor-suppressive role in the development of many organs, such as liver and lung, but the exact mechanism is still unknown. In addition, the involvement of MT1JP in osteosarcoma (OS) and its clinical values are unknown. In this study, the authors explored the interactions among lncRNA MT1JP, miR-646, and FOXK1 in OS. Materials and Methods: Expression levels of MT1JP in both tumor and nontumor tissues from 42 early stage OS patients were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Plasma levels of MT1JP in both OS patients (n = 42) and healthy controls (n = 42) were also measured by RT-qPCR. ROC curve as used for diagnostic analysis. Overexpression experiments were performed to analyze the interaction among MT1JP, miR-646, and FGF2. Cell invasion and migration were analyzed by Transwell assays. Results: The authors found that MT1JP was significantly downregulated in OS tissues than in adjacent noncancer tissues. In addition, plasma MT1JP was also downregulated in OS patients than in healthy controls. The lower plasma levels of MT1JP in OS patients distinguished early stage OS patients from healthy controls. miR-646 was positive, but FGF2 was negatively correlated with MT1JP across OS tissues. The MT1JP overexpression upregulated miR-646 and downregulated FGF2, while the miR-646 overexpression downregulated FGF2, but showed no significant effects on the MT1JP expression. MT1JP and miR-646 overexpression inhibited the migration and invasion of OS cells. The FGF2 overexpression played the opposite role and attenuated the effects of MT1JP and miR-646 overexpression. Conclusions: In conclusion, MT1JP might downregulate FGF2 through miR-646 to inhibit OS cell migration and invasion. The downregulation of plasma circulating MT1JP may serve as an early diagnostic biomarker for OS.

Long noncoding RNA MT1JP inhibits proliferation, invasion, and migration while promoting apoptosis of glioma cells through the activation of PTEN/Akt signaling pathway.

This study is carried out to elucidate the role of long noncoding RNAs (lncRNAs) MT1JP in proliferation, invasion, migration, and apoptosis of glioma cells through the regulation of PTEN/Akt signaling pathway. The expression of MT1JP in 80 normal brain tissues and 138 glioma tissues, as well as glioma cell lines, was detected by quantitative reverse-transcription polymerase chain reaction. Besides, glioma cells with overexpression and low expression of MT1JP were constructed to confirm the role of MT1JP in proliferation, invasion, migration, and apoptosis of glioma cells and the growth of glioma cells in vivo through the regulation of PTEN/Akt signaling pathway. MT1JP expression was downregulated in glioma tissues and cells. The low expression of MT1JP was considered as an independent risk factor for predicting overall survival in gliomas. After transfection of MT1JP overexpression plasmid, glioma cells showed decreased proliferation, migration and invasion ability, increased apoptosis rate, and decreased the tumorigenic ability of nude mice. The trends were opposite in glioma cells transfected with MT1JP poor expression plasmid. Collectively, our study suggests that lncRNA MT1JP is responsible for inhibiting proliferation, invasion, and migration while promoting apoptosis of glioma cells through the activation of PTEN/Akt signaling pathway.

Retracted: LncRNA MT1JP functions as a tumor suppressor via regulating miR-214-3p expression in bladder cancer.

Growing evidence suggested that the long noncoding RNAs (lncRNAs) regulate several pathophysiological processes in tumorigenesis and may be new biomarkers for tumor therapy. In this study, we studied the expression and role of lncRNA MT1JP in the development of bladder cancer. We demonstrated that the expression of MT1JP was downregulated in bladder tumor samples and cell lines. Ectopic expression of MT1JP suppressed cell proliferation, cycle, and invasion in bladder cancer. In addition, our result suggested that miR-214-3p overexpression decreased the luciferase activity of wild-type MT1JP but not mutated-type MT1JP and elevated expression of MT1JP decreased miR-214-3p expression in the bladder cancer cell. Furthermore, we indicated that the expression of miR-214-3p was upregulated in bladder tumor samples and cell lines. Ectopic expression of miR-214-3p promoted cell proliferation, cycle, and invasion in bladder cancer. MT1JP suppressed cell proliferation, cycle, and invasion via negative modulation of miR-214-3p in bladder cancer. These data suggested that lncRNA MT1JP acts a tumor suppressor gene in bladder cancer progression, considering MT1JP as a new therapeutic target in bladder cancer.

MT1JP inhibits tumorigenesis and enhances cisplatin sensitivity of breast cancer cells through competitively binding to miR-24-3p.

Accumulating evidence indicates that long non-coding RNAs (lncRNAs) play a key role in the development of many human cancers. MT1JP is a lncRNA that is reportedly involved in gastric cancer development, but a biological role and mechanism for MT1JP in breast cancer is unknown. Here, we found that MT1JP expression was significantly down-regulated in breast cancer tissues and cell lines, and that decreased MT1JP expression was associated with breast cancer progression and poor survival of breast cancer patients. Additionally, we found that overexpression of MT1JP in breast cancer cells significantly inhibited cell proliferation and invasion, and also enhanced the cisplatin sensitivity of breast cancer cells. We then investigated a possible mechanism for these results, finding that MT1JP binds to and negatively regulates miR-24-3p, which is known to be an oncogene in some human cancers. Our rescue experiments showed that the tumor suppressive and cisplatin-sensitizing functions of MT1JP were mediated by negative regulation of miR-24-3p. Finally, western blot results showed that MT1JP inhibited the Wnt/ß-catenin signaling pathway. Collectively, our data indicate that MT1JP functions as an anti-tumor lncRNA, enhances cisplatin sensitivity in breast cancer, and may serve as a novel diagnostic and therapeutic marker of breast cancer.

LncRNA MT1JP Suppresses Gastric Cancer Cell Proliferation and Migration Through MT1JP/MiR-214-3p/RUNX3 Axis.

BACKGROUND/AIMS: Emerging evidence points towards an important role of long noncoding RNAs (lncRNAs) in the tumorigenesis and progression of gastric cancer (GC). MT1JP has recently been reported to be differentially expressed and act as a tumor suppressor in different tumors, with its mechanisms not fully understood in GC. METHODS: RT-qPCR was used to detect the expression of MT1JP, miR-214-3p and RUNX3 in tumor tissues and cell lines of GC. The CCK-8 assay, colony formation, Transwell assay and wound healing assay were used to evaluate the proliferation, invasion and migration of GC cells, respectively. Bioinformatics analysis and luciferase reporter assay were performed to disclose the interaction between MT1JP, miR-214-3p and RUNX3. Western blot and immunofluorescence were applied to assess the downstream signaling of RUNX3. RESULTS: MT1JP was found downregulated in GC tissues and cells. Low expression of MT1JP was significantly correlated with advanced TNM stage and lymphatic metastasis. The expression of plasma MT1JP was also found decreased in GC patients compared to healthy controls, with an area under the ROC curve (AUC) of 0.649 for diagnosis of GC. Gain- and loss-of-function of MT1JP revealed that MT1JP functioned as a ceRNA for miR-214-3p to facilitate RUNX3 expression and then upregulated p21 and Bim levels suppressing GC cell proliferation, invasion and migration, and promoting apoptosis. Furthermore, MT1JP overexpression suppressed tumor growth and inhibited the expression of miR-214-3p and proliferation antigen Ki-67, but increased the expression of RUNX3, p21 and Bim in vivo. CONCLUSIONS: Our results suggest a potential ceRNA regulatory network involving MT1JP regulates RUNX3 expression by competitively binding endogenous miR-214-3p in tumorigenesis and progression of GC. This mechanism may contribute to a better understanding of GC pathogenesis and provide potential therapeutic strategy for GC.

LncRNA MT1JP functions as a ceRNA in regulating FBXW7 through competitively binding to miR-92a-3p in gastric cancer.

BACKGROUND: Emerging evidence has shown that dysregulation function of long non-coding RNAs (lncRNAs) implicated in gastric cancer (GC). However, the role of the differentially expressed lncRNAs in GC has not fully explained. METHODS: LncRNA expression profiles were determined by lncRNA microarray in five pairs of normal and GC tissues, further validated in another 75 paired tissues by quantitative real-time PCR (qRT-PCR). Overexpression of lncRNA MT1JP was conducted to assess the effect of MT1JP in vitro and in vivo. The biological functions were demonstrated by luciferase reporter assay, western blotting and rescue experiments. RESULTS: LncRNA MT1JP was significantly lower in GC tissues than adjacent normal tissues, and higher MT1JP was remarkably related to lymph node metastasis and advance stage. Besides, GC patients with higher MT1JP expression had a well survival. Functionally, overexpression of lncRNA MT1JP inhibited cell proliferation, migration, invasion and promoted cell apoptosis in vitro, and inhibited tumor growth and metastasis in vivo. Functional analysis showed that lncRNA MT1JP regulated FBXW7 expression by competitively binding to miR-92a-3p. MiR-92a-3p and down-regulated FBXW7 reversed cell phenotypes caused by lncRNA MT1JP by rescue analysis. CONCLUSION: MT1JP, a down-regulated lncRNA in GC, was associated with malignant tumor phenotypes and survival of GC. MT1JP regulated the progression of GC by functioning as a competing endogenous RNA (ceRNA) to competitively bind to miR-92a-3p and regulate FBXW7 expression. Our study provided new insight into the post-transcriptional regulation mechanism of lncRNA MT1JP, and suggested that MT1JP may act as a potential therapeutic target and prognosis biomarker for GC.

LncRNA MT1JP functions as a tumor suppressor by interacting with TIAR to modulate the p53 pathway.

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play important roles in transcriptional regulation, whereas the extent to which the lncRNAs also function at the posttranscriptional level is less known. In the present study, we report a lncRNA named MT1JP which acts as a tumor suppressor through a posttranscriptional mechanism. We found that MT1JP is differentially expressed in tumor tissues by analyzing data from a customized microarray applied to 76 pairs of matched normal and cancer tissue samples. By associating with the RNA-binding protein TIAR, MT1JP enhanced the translation of the master transcription factor p53, thereby regulating a series of pathways involving p53, such as the cell cycle, apoptosis and proliferation. When MT1JP was down-regulated, the protein level of p53 declined, which in turn accelerated cell deterioration and tumor formation. Moreover, differential expression of MT1JP in cancerous and normal tissues suggests that it may be a promising prognostic marker and a therapeutic target. Taken together, we identified MT1JP as a critical factor in restraining cell transformation by modulating p53 translation through interactions with TIAR, and this finding is likely to shed new light on future investigations about posttranscriptional or translational effects of lncRNAs during cell transformation.