Proteinase-activated Receptor 2 Promotes Cancer Cell Migration through RNA Methylation-mediated Repression of miR-125b

Proteinase activated-receptor 2 (PAR₂) participates in cancer metastasis promoted by serine proteinases. The current study aimed to test the molecular mechanism by which PAR₂ promotes cancer cell migration. In different cancer cells, activation of PAR₂ by activating peptide (PAR₂-AP) dramatically increased cell migration, whereas knock down of PAR₂ inhibited cellular motility. The PAR₂ activation also repressed miR-125b expression while miR-125b mimic successfully blocked PAR₂-induced cell migration. Moreover, Grb associated-binding protein 2 (Gab2) was identified as a novel target gene of miR-125b and it mediated PAR₂-induced cell migration. The correlation of PAR₂ with miR-125b and Gab2 was further supported by the findings obtained from human colorectal carcinoma specimens. Remarkably, knock down of NOP2/Sun domain family, member 2 (NSun2), a RNA methyltransferase, blocked the reduction in miR-125b induced by PAR₂. Furthermore, PAR₂ activation increased the level of N⁶-methyladenosine (m⁶A)-containing pre-miR-125b in NSun2-dependent manner. Taken together, our results demonstrated that miR-125b mediates PAR₂-induced cancer cell migration by targeting Gab2 and that NSun2-dependent RNA methylation contributes to the down-regulation of miR-125b by PAR₂ signaling. These findings suggest a novel epigenetic mechanism by which microenvironment regulates cancer cell migration by altering miRNA expression.     

Predictive value of protease-activated receptor-2 (PAR2) in cervical cancer metastasis

Metastasis is the primary cause of an unfavourable prognosis in patients with malignant cancer. Over the last decade, the role of proteinases in the tumour microenvironment has attracted increasing attention. As a sensor of proteinases, proteinase-activated receptor 2 (PAR₂) plays crucial roles in the metastatic progression of cervical cancer. In the present study, the expression of PAR₂ in multiple types of cancer was analysed by Gene Expression Profiling Interactive Analysis (GEPIA). Kaplan-Meier plotter was used to calculate the correlation between survival and the levels of PAR₂, Grb-associated binding protein 2(Gab2) and miR-125b. Immunohistochemistry (IHC) was performed to examine PAR₂ expression in a tissue microarray (TMA) of CESCs. Empower Stats was used to assess the predictive value of PAR₂ in the metastatic potential of CESC. We found that PAR₂ up-regulation was observed in multiple types of cancer. Moreover, PAR₂ expression was positively correlated with the clinicopathologic characteristics of CESC. miR-125b and its target Gab2, which are strongly associated with PAR₂-induced cell migration, are well-characterized as predictors of the prognostic value of CESC. Most importantly, the Cancer Genome Atlas (TCGA) data set analysis showed that the area under the curve (AUC) of the PAR₂ model was significantly greater than that of the traditional model (0.833 vs 0.790, P < .05), demonstrating the predictive value of PAR₂ in CESC metastasis. Our results suggest that PAR₂ may serve as a prognostic factor for metastasis in CESC patients.     

MicroRNA-218 Inhibits Cell Cycle Progression and Promotes Apoptosis in Colon Cancer by Downregulating BMI1 Polycomb Ring Finger Oncogene

Deregulated miRNAs participate in colorectal carcinogenesis. In this study, miR-218 was found to be downregulated in human colorectal cancer (CRC) by miRNA profile assay. miR-218 was silenced or downregulated in all five colon cancer cells (Caco2, HT29, SW620, HCT116 and LoVo) relative to normal colon tissues. miR-218 expression was significantly lower in 46 CRC tumor tissues compared with their adjacent normal tissues (P < 0.001). Potential target genes of miR-218 were predicted and BMI1 polycomb ring finger oncogene (BMI-1), a polycomb ring finger oncogene, was identified as one of the potential targets. Upregulation of BMI-1 was detected in CRC tumors compared with adjacent normal tissues (P < 0.001) and in all five colon cancer cell lines. Transfection of miR-218 in colon cancer cell lines (HCT116, HT29) significantly reduced luciferase activity of the wild-type construct of BMI-1 3′ untranslated region (3′UTR) (P < 0.001), whereas this effect was not seen in the construct with mutant BMI-1 3′UTR, indicating a direct and specific interaction of miR-218 with BMI-1. Ectopic expression of miR-218 in HCT116 and HT29 cells suppressed BMI-1 mRNA and protein expression. In addition, miR-218 suppressed protein expression of BMI-1 downstream targets of cyclin-dependent kinase 4, a cell cycle regulator, while upregulating protein expression of p53. We further revealed that miR-218 induced apoptosis (P < 0.01), inhibited cell proliferation (P < 0.05) and promoted cell cycle arrest in the G2 phase (P < 0.01). In conclusion, miR-218 plays a pivotal role in CRC development through inhibiting cell proliferation and cycle progression and promoting apoptosis by downregulating BMI-1.     

miR-937-5p targets SOX17 to modulate breast cancer cell cycle and cell proliferation through the Wnt signaling pathway

Breast cancer is one of the most frequent cancers in women and the globally leading cause of cancer-related deaths. Bioinformatics and experimental analyses found that miR-937-5p may play a proto-oncogenic role in breast cancer; however, the specific effects and the molecular mechanism need further investigation. GSEA-KEGG and GSEA-GO suggested that miR-937-5p might be related to cell cycle and DNA replication. The experimental data indicated that miR-937-5p inhibition significantly repressed the proliferation of breast carcinoma cells and elicited S-phase cell cycle arrest. Meanwhile, the protein levels of proliferating marker ki-67 and cell cycle regulators Cyclin A2, Cyclin B1, CDK1, and Cyclin D1 were also decreased by miR-937-5p inhibition. miR-937-5p could directly bind to and negatively regulate SOX17. SOX17 overexpression also significantly repressed the proliferation of breast carcinoma cells and elicited S-phase cell cycle arrest and decreased ki-67, β-catenin, c-Myc, Cyclin A2, Cyclin B1, Cyclin D1, and CDK1 protein contents. More importantly, the effects of miR-937-5p were reversed by SOX17.     

microRNA-16-5p enhances radiosensitivity through modulating Cyclin D1/E1–pRb–E2F1 pathway in prostate cancer cells

Prostate cancer (CaP) is the second most common cancer in men worldwide in 2012, and radiation therapy is one of the most common definitive treatment options for localized CaP. However, radioresistance is a major challenge for the current radiotherapy, accumulating evidences suggest microRNAs (miRNAs), as an important regulator in cellular ionizing radiation (IR) responses, are closely correlated with radiosensitivity in many cancers. Here, we identified microRNA-16-5p(miR-16-5p) is significantly upregulated in CaP LNCaP cells following IR and can enhance radiosensitivity through modulating Cyclin D1/E1–pRb–E2F1 pathway. To identify the expression profile of miRNAs in CaP cells exposed to IR, we performed human miRNA probe hybridization chip analysis and miR-16-5p was found to be significantly overexpressed in all treatment groups that irradiated with different doses of X-rays and heavy ions (¹²C⁶⁺). Furthermore, overexpression of miR-16-5p suppressed cell proliferation, reduced cell viability, and induced cell cycle arrest at G0/G1 phase, resulting in enhanced radiosensitivity in LNCaP cells. Additionally, miR-16-5p specifically targeted the Cyclin D1/E1–3′-UTR in LNCaP cells and affected the expression of Cyclin D1/E1 in both mRNA and protein levels. Taken together, miR-16-5p enhanced radiosensitivity of CaP cells, the mechanism may be through modulating Cyclin D1/Cyclin E1/pRb/E2F1 pathway to cause cell cycle arrest at G0/G1 phase. These findings provided new insight into the correlation between miR-16-5p, cell cycle arrest, and radiosensitivity in CaP, revealed a previously unrecognized function of miR-16-5p–Cyclin D1/E1–pRb–E2F1 regulation in response to IR and may offer an alternative therapy to improve the efficiency of conventional radiotherapy.     

miR-140-3p impedes the proliferation of human cervical cancer cells by targeting RRM2 to induce cell-cycle arrest and early apoptosis

Cervical cancer is a critically malignant tumor with the second mortality of females worldwide. MicroRNAs (miRNAs) are short but regulatory non-coding RNAs playing a pivotal role in many biological processes including tumorigenesis. However, the exact role of miR-140-3p in cervical cancer remains to be elucidated. Here we identified that miR-140-3p was significantly reduced in cervical cancer tissues by comprehensive analysis of TCGA data, hinting that higher expression level of miR-140-3p predicted a good clinical prognosis. Quantitative real-time PCR (RT-qPCR) assay was performed to confirm the negative correlation between miR-140-3p expression level and human cervical cancer tissues as well as various cervical cancer cell lines. To clarify the certain role of miR-140-3p, forced expression by microRNA mimics was applied in Caski and C33A cells, showing that miR-140-3p overexpression significantly impeded the proliferation of cervical cancer cells by cell count kit (CCK-8) assay. Western blot analysis of cell cycle-related proteins Cyclin A, Cyclin B1 and Cyclin D1 have further confirmed the cell cycle arrest was induced by the ectopic expression of miR-140-3p. Annexin-V based FACS analysis also found the simultaneous appearance of early apoptotic cell population in miR-140-3p overexpression cells. The protein level of BCL-2 was attenuated in accompany with elevated Bax and Cleaved caspase-3 protein, indicating miR-140-3p overexpression induced early apoptosis. Mechanistically, we demonstrated that miR-140-3p could target the 3′UTR of RRM2 which has been proved to be highly involved in the onset of cancer. Furthermore, upregulation of miR-140-3p and RRM2 failed to inhibit the proliferation of human cervical cancer cells, revealing that RRM2 served as the target downstream gene of miR-140-3p abolishing its ability as a tumor suppressor. Overall, we figured out the new role of miR-140-3p in cervical cancer and concluded that miR-140-3p was a candidate of cancer control in preclinical.     

miRNA-29c Suppresses Lung Cancer Cell Adhesion to Extracellular Matrix and Metastasis by Targeting Integrin β1 and Matrix Metalloproteinase2 (MMP2)

Our pilot study using miRNA arrays found that miRNA-29c (miR-29c) is differentially expressed in the paired low-metastatic lung cancer cell line 95C compared to the high-metastatic lung cancer cell line 95D. Bioinformatics analysis shows that integrin β1 and matrix metalloproteinase 2 (MMP2) could be important target genes of miR-29c. Therefore, we hypothesized that miR-29c suppresses lung cancer cell adhesion to extracellular matrix (ECM) and metastasis by targeting integrin β1 and MMP2. The gain-of-function studies that raised miR-29c expression in 95D cells by using its mimics showed reductions in cell proliferation, adhesion to ECM, invasion and migration. In contrasts, loss-of-function studies that reduced miR-29c by using its inhibitor in 95C cells promoted proliferation, adhesion to ECM, invasion and migration. Furthermore, the dual-luciferase reporter assay demonstrated that miR-29c inhibited the expression of the luciferase gene containing the 3′-UTRs of integrin β1 and MMP2 mRNA. Western blotting indicated that miR-29c downregulated the expression of integrin β1 and MMP2 at the protein level. Gelatin zymography analysis further confirmed that miR-29c decreased MMP2 enzyme activity. Nude mice with xenograft models of lung cancer cells confirmed that miR-29c inhibited lung cancer metastasis in vivo, including bone and liver metastasis. Taken together, our results demonstrate that miR-29c serves as a tumor metastasis suppressor, which suppresses lung cancer cell adhesion to ECM and metastasis by directly inhibiting integrin β1 and MMP2 expression and by further reducing MMP2 enzyme activity. The results show that miR-29c may be a novel therapeutic candidate target to slow lung cancer metastasis.     

miR-3940-5p Functions as a Tumor Suppressor in Non–Small Cell Lung Cancer Cells by Targeting Cyclin D1 and Ubiquitin Specific Peptidase-28

miR-3940-5p level was lower in non–small cell lung cancer (NSCLC) tumor tissues than that in the matched tumor-adjacent tissues and correlated with clinicopathological features. Cyclin D1 (CCND1), a key driver of malignant transformation in NSCLC, was overexpressed in many cancers, including NSCLC. The ubiquitin specific peptidase-28 (USP28) was also overexpressed in NSCLC and associated with poor prognosis of NSCLC patients. We searched for miR-3940-5p targets by using TargetScan and miRanda online tools and found that CCND1 and USP28 were potential targets of miR-3940-5p. Based on these findings, we speculated that miR-3940-5p might target CCND1 and USP28 to inhibit NSCLC growth. We determined the expression of miR-3940-5p, CCND1, and USP28 by quantitative real-time polymerase chain reaction and Western blot assays, respectively, and found downregulation of miR-3940-5p and upregulation of CCND1 and USP28 in NSCLC tissues and cell lines. Cell proliferation and apoptosis assays showed that miR-3940-5p suppressed proliferation and promoted apoptosis in NSCLC cells, and silencing CCND1 and USP28 both recapitulated the effects of miR-3940-5p on NSCLC cells. Furthermore, we verified that CCND1 and USP28 were direct targets of miR-3940-5p and also found that the effects of NSCLC cell proliferation and apoptosis by miR-3940-5p were attenuated by overexpression of CCND1 or USP28. The animal experiments also showed that overexpression of miR-3940-5p inhibited the growth of NSCLC tumors in vivo. These results confirmed our speculation that miR-3940-5p inhibits proliferation and induces apoptosis in NSCLC cells by targeting CCND1 and USP28. These findings facilitate a better understanding of the molecular mechanisms underlying NSCLC initiation and progression and provide promising diagnostic markers and therapeutic targets for NSCLC.     

Growth inhibitory effects of three miR-129 family members on gastric cancer

Reduced expression of microRNA-129 (miR-129) has been reported in several types of tumor cell lines as well as in primary tumor tissues. However, little is known about how miR-129 affects cell proliferation in gastric cancer. Here, we show that all miR-129 family members, miR-129-1-3p, miR-129-2-3p, and miR-129-5p, are down-regulated in gastric cancer cell lines compared with normal gastric epithelial cells. Furthermore, using the real-time cell analyzer assay to observe the growth effects of miR-129 on gastric cancer cells, we found that all three mature products of miR-129 showed tumor suppressor activities. To elucidate the molecular mechanisms underlying down-regulation of miR-129 in gastric cancer, we analyzed the effects of miR-129 mimics on the cell cycle. We found that increased miR-129 levels in gastric cancer cells resulted in significant G₀/G₁ phase arrest. Interestingly, we showed that cyclin dependent kinase 6 (CDK6), a cell cycle-associated protein involved in G₁-S transition, was a target of miR-129. We also found that expression of the sex determining region Y-box 4 (SOX4) was inversely associated with that of miR-129-2-3p and miR-129-5p but not of miR-129-1-3p. Together, our data indicate that all miR-129 family members, not only miR-129-5p, as previously thought, play an important role in regulating cell proliferation in gastric cancer.     

The Loss of miR-26a-Mediated Post-Transcriptional Regulation of Cyclin E2 in Pancreatic Cancer Cell Proliferation and Decreased Patient Survival

Background

miR-26a plays a critical role in tumorigenesis, either as a tumor suppressor or as an oncogenic miRNA, depending on different tumor types. However, the function of miR-26a in pancreatic cancer has not been clearly elucidated. The present study was designed to determine the roles of miR-26a in pancreatic cancer and its association with the survival of patients with pancreatic cancer.

Methods

The expression of miR-26a was examined in 15 pairs of pancreatic duct adenocarcinoma (PDAC) and their adjacent benign pancreatic tissues (ABPT), by qRT-PCR. The results were confirmed by in situ hybridization using two panels of 106 PDACs and their ABPT microarray. The association of miR-26a expression with overall survival was determined. The proliferation and cell cycle distribution of Capan-2, SW-1990, and Panc-1 cells, transfected with miR-26a mimics or a miR-26a inhibitor, were assessed using the Cell Counting Kit-8 assay and flow cytometry, respectively. The cell tumorigenicity was evaluated via murine xenograft experiments. Cyclin D2, E2, EZH2, and PCNA levels were analyzed by Western blot and immunohistochemistry.

Results

miR-26a was expressed in the cytoplasm of pancreatic ductal epithelial cells, whereas its expression was significantly downregulated in PDAC tissues compared with that of ABPT. Patients with low miR-26a expression had a significantly shorter survival than those with high miR-26a expression. The in vitro and in vivo assays showed that overexpression of miR-26a resulted in cell cycle arrest, inhibited cell proliferation, and decreased tumor growth, which was associated with cyclin E2 downregulation.

Conclusions

miR-26a is an important suppressor of pancreatic ductal carcinoma, and can prove to be a novel prognostic factor and therapeutic target for pancreatic cancer treatment.     

lncRNA RPL34-AS1通过靶向调控miR-575表达对卵巢癌SKOV3细胞增殖和凋亡的影响

目的探究RPL34-AS1对卵巢癌细胞增殖、迁移的影响及其作用机制。 方法取对数生长期SKOV3细胞用无血清培养基同步化12 h,将pcDNA、pcDNA-RPL34-AS1、si-NC、si-RPL34-AS1、anti-miR-NC、anti-miR-575转染至SKOV3细胞中,分别记为pcDNA组、pcDNA-RPL34-AS1组、si-NC组、si-RPL34-AS1组、anti-miR-NC组、anti-miR-575组;将pcDNA-RPL34-AS1与miR-NC、miR-575分别共转染至SKOV3细胞中,记为pcDNA-RPL34-AS1+miR-NC组、pcDNA-RPL34-AS1+miR-575组。实时荧光定量PCR （RT-qPCR）检测临床组织标本及转染后各组细胞中RPL34-AS1和miR-575的表达水平;双荧光素酶报告实验检测RPL34-AS1和miR-575的靶向关系;四甲基偶氮唑盐比色法（MTT）检测细胞存活率;流式细胞术检测细胞凋亡;蛋白质印迹（Western blot）法检测细胞周期蛋白D1（Cyclin D1）、细胞周期蛋白依赖性激酶抑制剂1A （p21）、B细胞淋巴瘤/白血病-2 （Bcl-2）、Bcl-2相关X蛋白（Bax）蛋白表达水平。两组间比较采用独立样本t检验,多组间比较采用单因素方差分析,组间两两比较采用LSD-t检验。 结果与癌旁组织相比,卵巢癌组织中RPL34-AS1表达水平降低（1.00±0.08比0.47±0.05）,miR-575表达水平升高（1.01±0.07比3.12±0.28）（P < 0.05）。转染si-RPL34-AS1后,细胞活性升高（48 h：0.68±0.06比0.55±0.05;72 h：0.99±0.08比0.71±0.06）,G1期细胞所占比例降低（13.42±1.38比32.15±2.11）,S期细胞所占比例升高（53.75±5.22比34.69±3.41）,细胞凋亡率降低（4.31±0.42比9.25±0.91）,CyclinD1、Bcl-2表达水平升高（0.92±0.08比0.71±0.07;0.86±0.07比0.61±0.06）,p21、Bax表达水平降低（0.13±0.02比0.29±0.03;0.19±0.02比0.31±0.03） （P均< 0.05）。RPL34-AS1靶向调控miR-575,过表达RPL34-AS1或抑制miR-575后可抑制细胞活性,阻滞细胞周期和促进细胞凋亡。miR-575过表达逆转了RPL34-AS1过表达对卵巢癌SKOV3细胞增殖抑制和凋亡促进的作用。 结论过表达RPL34-AS1可抑制卵巢癌SKOV3细胞增殖,促进细胞凋亡,其机制可能与下调miR-575有关。     

Influence of miRNA-106b and miRNA-135a on butyrate-regulated expression of p21 and Cyclin D2 in human colon adenoma cells

Epigenetic and posttranslational modifications of the expression of cell cycle-relevant genes or proteins like p21, e.g., by miRNAs are crucial mechanisms in the development or prevention of colon cancer. The present study investigated the influence of butyrate and trichostatin A (TSA) as histone deacetylase inhibitors on the expression of colon cancer-relevant miRNA (miR-135a, miR-135b, miR-24, miR-106b, miR-let-7a) in LT97 colon adenoma cells as a model of an early stage of colon carcinogenesis. The impact of distinct miRNAs (miR-106b, miR-135a) on butyrate-mediated regulation of p21 and Cyclin D2 gene and protein expression as well as the effect on LT97 cell proliferation (non-transfected, miR-106b and miR-135a mimic transfected) was analyzed. Butyrate and partial TSA reduced the expression of miR-135a, miR-135b, miR-24 and miR-let-7a (~0.5-fold, 24 h) and miR-24, miR-106b and miR-let-7a (~0.5–0.7-fold, 48 h) in LT97 cells. Levels of p21 mRNA and protein were significantly increased by butyrate and TSA (~threefold and 4.5-fold, respectively, 24 h) in non-transfected but not in miR-106b transfected LT97 cells. Levels of Cyclin D2 mRNA were significantly reduced by butyrate and TSA (~0.3-fold, 24 h) in non-transfected and miR-135a-transfected LT97 cells, whereas protein levels were predominantly not influenced. MiR-106b and miR-135a significantly reduced butyrate-/TSA-mediated inhibition of LT97 cell proliferation (72 h). These results indicate that butyrate is able to modify colon cancer-relevant miRNAs like miR-106b and miR-135a which are involved in the regulation of cell cycle-relevant genes like p21 and might influence inhibition of adenoma cell proliferation.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-015-0500-4) contains supplementary material, which is available to authorized users.     

新型microRNA—miR-34在肿瘤中的研究进展

miR-34是一类保守的、非编码miRNA。人类miR-34包括miR-34a、miR-34b和miR-34c等,在多种肿瘤中都呈现非正常表达。miR-34通过被p53激活,抑制E2F3、Bcl-2、c—myc、CDK4、CDK6、Cyclin D1以及Cyclin E2的表达,使肿瘤细胞停滞在G1期,抑制肿瘤细胞的生长,诱导肿瘤细胞凋亡,并通过E2F3、SIRT1与p53形成正反馈环路,不断增强其自身和p53的作用。本文就miR-34的研究进展进行综述。