Potential Tumor Suppressor Role Research Articles

Systematic Analysis of Gene Expression Alterations and Clinical Outcomes for Long-Chain Acyl-Coenzyme A Synthetase Family in Cancer.

Dysregulated lipid metabolism contributes to cancer progression. Our previous study indicates that long-chain fatty acyl-Co A synthetase (ACSL) 3 is essential for lipid upregulation induced by endoplasmic reticulum stress. In this report, we aimed to identify the role of ACSL family in cancer with systematic analysis and in vitro experiment. We explored the ACSL expression using Oncomine database to determine the gene alteration during carcinogenesis and identified the association between ACSL expression and the survival of cancer patient using PrognoScan database. ACSL1 may play a potential oncogenic role in colorectal and breast cancer and play a potential tumor suppressor role in lung cancer. Co-expression analysis revealed that ACSL1 was coexpressed with MYBPH, PTPRE, PFKFB3, SOCS3 in colon cancer and with LRRFIP1, TSC22D1 in lung cancer. In accordance with PrognoScan analysis, downregulation of ACSL1 in colon and breast cancer cell line inhibited proliferation, migration, and anchorage-independent growth. In contrast, increase of oncogenic property was observed in lung cancer cell line by attenuating ACSL1. High ACSL3 expression predicted a better prognosis in ovarian cancer; in contrast, high ACSL3 predicted a worse prognosis in melanoma. ACSL3 was coexpressed with SNUPN, TRIP13, and SEMA5A in melanoma. High expression of ACSL4 predicted a worse prognosis in colorectal cancer, but predicted better prognosis in breast, brain and lung cancer. ACSL4 was coexpressed with SERPIN2, HNRNPCL1, ITIH2, PROCR, LRRFIP1. High expression of ACSL5 predicted good prognosis in breast, ovarian, and lung cancers. ACSL5 was coexpressed with TMEM140, TAPBPL, BIRC3, PTPRE, and SERPINB1. Low ACSL6 predicted a worse prognosis in acute myeloid leukemia. ACSL6 was coexpressed with SOX6 and DARC. Altogether, different members of ACSLs are implicated in diverse types of cancer development. ACSL-coexpressed molecules may be used to further investigate the role of ACSL family in individual type of cancers.

Epigenetically silenced GNG4 inhibits SDF1α/CXCR4 signaling in mesenchymal glioblastoma.

The most common and aggressive form of primary brain tumor in adults is glioblastoma (GBM). From the global DNA methylation profiling study, previously published from our laboratory, we identified Guanine Nucleotide binding-protein Gamma subunit 4 (GNG4) to be one of the most hyper methylated and down regulated genes in GBM. GBM derived cell lines showed reduced GNG4 transcript levels, which could be reversed by methylation inhibitor treatment. Bisulphite sequencing confirmed the methylation status in glioblastoma tumor tissue and GBM derived cell lines. Overexpression of GNG4 was found to inhibit proliferation and colony formation of GBM cell lines and in vitro transformation of immortalized human astrocytes, thus suggesting a potential tumor suppressor role of GNG4 in GBM. Correlation of GNG4 transcript levels with that of all GPCRs from TCGA data revealed chemokine receptors as the potential target of GNG4. Furthermore, exogenous over expression of GNG4 inhibited SDF1α/CXCR4-dependent chemokine signaling as seen by reduced pERK and pJNK and GBM cell migration. The inhibitory association between GNG4 and SDF1α/CXCR4 was more evident in mesenchymal subtype of GBM. Thus, this study identifies GNG4 as an inhibitor of SDF1α/CXCR4-dependent signaling and emphasizes the significance of epigenetic inactivation of GNG4 in glioblastoma, especially in mesenchymal subtype.

MiR-363-3p inhibits the epithelial-to-mesenchymal transition and suppresses metastasis in colorectal cancer by targeting Sox4

Epithelial-to-mesenchymal transition (EMT) plays an essential role in cancer invasion and metastasis and is associated with tumor recurrence in colorectal cancer (CRC). However, the mechanism that contributes to EMT have not been fully understood in CRC. In the present study, we showed that miR-363-3p was frequently down-regulated in CRC tissue specimens with lymph node metastasis. Moreover, we demonstrated that down-regulation of miR-363-3p promoted CRC cell migration and invasion, and induced EMT in vitro and in vivo, revealing that miR-363-3p playes a potential tumor-suppressive role in CRC. Analysis of the underlying mechanisms revealed that miR-363-3p could regulate Sox4 expression by directly targeting its 3'untranslated region. Down-regulation of miR-363-3p increased Sox4 expression and induced EMT, while overexpression of miR-363-3p decreased Sox4 expression. Taken together, our findings indicate that miR-363-3p is involved in CRC metastasis and functions as a tumor suppressor via negatively regulating Sox4. Therefore, the up-regulation of miR-363-3p in human CRC may have therapeutic benefits.

DNA damage signalling barrier, oxidative stress and treatment-relevant DNA repair factor alterations during progression of human prostate cancer

The DNA damage checkpoints provide an anti-cancer barrier in diverse tumour types, however this concept has remained unexplored in prostate cancer (CaP). Furthermore, targeting DNA repair defects by PARP1 inhibitors (PARPi) as a cancer treatment strategy is emerging yet requires suitable predictive biomarkers. To address these issues, we performed immunohistochemical analysis of multiple markers of DNA damage signalling, oxidative stress, DNA repair and cell cycle control pathways during progression of human prostate disease from benign hyperplasia, through intraepithelial neoplasia to CaP, complemented by genetic analyses of TMPRSS2-ERG rearrangement and NQO1, an anti-oxidant factor and p53 protector. The DNA damage checkpoint barrier (γH2AX, pATM, p53) mechanism was activated during CaP tumorigenesis, albeit less and with delayed culmination compared to other cancers, possibly reflecting lower replication stress (slow proliferation despite cases of Rb loss and cyclin D1 overexpression) and progressive loss of ATM activator NKX3.1. Oxidative stress (8-oxoguanine lesions) and NQO1 increased during disease progression. NQO1 genotypes of 390 men did not indicate predisposition to CaP, yet loss of NQO1 in CaP suggested potential progression-opposing tumour suppressor role. TMPRSS2-ERG rearrangement and PTEN loss, events sensitizing to PARPi, occurred frequently along with heterogeneous loss of DNA repair factors 53BP1, JMJD1C and Rev7 (all studied here for the first time in CaP) whose defects may cause resistance to PARPi. Overall, our results reveal an unorthodox DNA damage checkpoint barrier scenario in CaP tumorigenesis, and provide novel insights into oxidative stress and DNA repair, with implications for biomarker guidance of future targeted therapy of CaP.

A novel AKT inhibitor, AZD5363, inhibits phosphorylation of AKT downstream molecules, and activates phosphorylation of mTOR and SMG-1 dependent on the liver cancer cell type.

Due to frequent phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway dysregulation, AKT is typically accepted as a promising anticancer therapeutic target. mTOR, in particular, represents a suitable therapeutic target for hepatocellular carcinoma, whilst suppressor with morphogenetic effect on genitalia family member-1 (SMG-1) is believed to serve a potential tumor suppressor role in human cancer. Despite SMG-1 and mTOR belonging to the same PI3K-related kinase family, the interactions between them are not yet fully understood. In the present study, a novel pyrrolopyrimidine-derived compound, AZD5363, was observed to suppress proliferation in liver cancer Hep-G2 and Huh-7 cells by inhibiting the phosphorylation of downstream molecules in the AKT signal pathway, in a dose- and time-dependent manner. AZD5363 activated the phosphorylation of mTOR, dependent on the liver cancer cell type, as it may have differing effects in various liver cancer cell lines. Additionally, AZD5363 also activated SMG-1 within the same liver cancer cells types, which subsequently activated the phosphorylation of mTOR. In conclusion, the present study indicates that AZD5363 inhibited phosphorylation of AKT downstream molecules, and activated phosphorylation of mTOR and SMG-1, dependent on the liver cancer type.

PDLIM2 and Its Role in Oncogenesis--Tumor Suppressor or Oncoprote?

PDZ and LIM domain containing protein 2 (PDLIM2), also known as Mystique or SLIM, is a member of the actinin-associated LIM family of proteins that play essential roles in cytoskeletone organization, cell differentiation and have been associated with oncogenesis. PDLIM2 is cytoskeletal and nuclear protein encoded by the Mystique gene localized on chromosome 8p21. PDLIM2 regulates stability and activity of several transcription factors, e. g. NF κB or STAT, and its deregulation is associated with several malignancies. PDLIM2 expression has been connected with both tumor suppression and tumorigenesis. PDLIM2 levels are epigenetically suppressed in different cancers due to Mystique promoter hypermetylation that blocks its transcription. PDLIM2 re expression is able to inhibit tumorigenicity and induces tumor cell death both in vitro and in vivo, which suggest potential tumor suppressor role of PDLIM2. On the other hand, PDLIM2 is highly expressed in cancer cell lines derived from metastatic cancer and its expression is associated with tumor progression and metastasis formation, indicating pro oncogenic role of PDLIM2. The aim of this review is to summarize current knowledge on the role of PDLIM2 in tumor formation and development, focusing on its prospective role as therapeutic target and offering potential explanations of its different functions in oncogenesis that were identified so far.

FOXD3 suppresses tumor growth and angiogenesis in non-small cell lung cancer

The transcription factor forkhead box D3 (FOXD3), widely studied as a transcriptional repressor in embryogenesis, participates in the carcinogenesis of many cancers. However, the expression pattern and role of FOXD3 in non-small cell lung cancer (NSCLC) have not been well characterized. We report that FOXD3 is significantly downregulated in NSCLC cell lines and clinical tissues. FOXD3 overexpression significantly inhibits cell growth and results in G1 cell cycle arrest in NSCLC A549 and H1299 cells. In a xenograft tumor model, FOXD3 overexpression inhibits tumor growth and angiogenesis. Remarkably, expression of vascular endothelial growth factor (VEGF) was reduced in FOXD3 overexpression models both in vitro and in vivo. These findings suggest that FOXD3 plays a potential tumor suppressor role in NSCLC progression and represents a promising clinical prognostic marker and therapeutic target for this disease.

MiR-181a-5p inhibits cell proliferation and migration by targeting Kras in non-small cell lung cancer A549 cells.

MicroRNAs play important roles in carcinogenesis and tumor progress. Lung cancer is the leading cause of cancer mortality worldwide. In this study, the function of miR-181a-5p was investigated in non-small-cell lung cancer (NSCLC). Results showed that miR-181a-5p was significantly decreased in NSCLC tissues and cell lines. The proliferation and migration of A549 cells transfected with miR-181a-5p mimic was significantly inhibited. Luciferase activity assay results demonstrated that two binding sites of Kras could be directly targeted by miR-181a-5p. Furthermore, Kras was down-regulated by miR-181a-5p at both transcriptional and translational levels. SiRNA-mediated Kras down-regulation could mimic the effects of miR-181a-5p mimic in A549 cells. Our findings suggest that miR-181a-5p plays a potential role in tumor suppression by partially targeting Kras and has the potential therapeutic application in NSCLC patients.

MicroRNA-10a is reduced in breast cancer and regulated in part through retinoic acid

BackgroundMicroRNAs (miRNAs) are short non-coding RNA molecules that play a critical role in mRNA cleavage and translational repression, and are known to be altered in many diseases including breast cancer. MicroRNA-10a (miR-10a) has been shown to be deregulated in various cancer types. The aim of this study was to investigate miR-10a expression in breast cancer and to further delineate the role of retinoids and thyroxine in regulation of miR-10a.MethodsFollowing informed patient consent and ethical approval, tissue samples were obtained during surgery. miR-10a was quantified in malignant (n = 103), normal (n = 30) and fibroadenoma (n = 35) tissues by RQ-PCR. Gene expression of Retinoic Acid Receptor beta (RARβ) and Thyroid Hormone receptor alpha (THRα) was also quantified in the same patient samples (n = 168). The in vitro effects of all-trans Retinoic acid (ATRA) and L-Thyroxine (T4) both individually and in combination, on miR-10a expression was investigated in breast cancer cell lines, T47D and SK-BR-3.ResultsThe level of miR-10a expression was significantly decreased in tissues harvested from breast cancer patients (Mean (SEM) 2.1(0.07)) Log10 Relative Quantity (RQ)) compared to both normal (3.0(0.16) Log10 RQ, p < 0.001) and benign tissues (2.6(0.17) Log10 RQ, p < 0.05). The levels of both RARβ and THRα gene expression were also found to be decreased in breast cancer patients compared to controls (p < 0.001). A significant positive correlation was determined between miR-10a and RARβ (r = 0.31, p < 0.001) and also with THRα (r = 0.32, p < 0.001). In vitro stimulation assays revealed miR-10a expression was increased in both T47D and SK-BR-3 cells following addition of ATRA (2 fold (0.7)). While T4 alone did not stimulate miR-10a expression, the combination of T4 and ATRA was found to have a positive synergistic effect.ConclusionThe data presented supports a potential tumour suppressor role for miR-10a in breast cancer, and highlights retinoic acid as a positive regulator of the microRNA.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1374-y) contains supplementary material, which is available to authorized users.

FBXO4 loss facilitates carcinogen induced papilloma development in mice

Cyclin D1 is frequently overexpressed in esophageal squamous cell carcinoma (ESCC) and is considered a key driver of this disease. Mutations in FBXO4, F-box specificity factor that directs SCF-mediated ubiquitylation of cyclin D1, occur in ESCC with concurrent overexpression of cyclin D1 suggesting a potential tumor suppressor role for FBXO4. To evaluate the contribution of FBXO4-dependent regulation cyclin D1 in esophageal squamous cell homeostasis, we exposed FBXO4 knockout mice to N-nitrosomethylbenzylamine (NMBA), an esophageal carcinogen. Our results revealed that loss of FBXO4 function facilitates NMBA induced papillomas in FBXO4 het (+/−) and null (−/−) mice both by numbers and sizes 11 months after single dose NMBA treatment at 2mg/kg by gavage when compared to that in wt (+/+) mice (P < 0.01). No significant difference was noted between heterozygous or nullizygous mice consistent with previous work. To assess cyclin D1/CDK4 dependence, mice were treated with the CDK4/6 specific inhibitor, PD0332991, for 4 weeks. PD0332991 treatment (150mg/kg daily), reduced tumor size and tumor number. Collectively, our data support a role for FBXO4 as a suppressor of esophageal tumorigenesis.

The tumor-suppressor gene LZTS1 suppresses colorectal cancer proliferation through inhibition of the AKT–mTOR signaling pathway

The Leucine zipper tumor suppressor gene 1 (LZTS1/FEZ1) gene was originally identified as a potential tumor suppressor. However, the expression pattern and the role of LZTS1 in the progression of colorectal cancer (CRC) have not been well characterized. Herein, we reported that LZTS1 was markedly reduced in CRC tissues compared with matched adjacent normal intestine epithelial tissues. In analysis of 160 CRC specimens, we revealed that decreased expression of LZTS1 was correlated to aggressive characteristics and poor survival of patients with CRC. Moreover, we found that expression of LZTS1 in CRC cells significantly inhibited cell proliferation in vitro and prohibited tumor growth in vitro. On the contrary, silence of LZTS1 promoted cell proliferation and tumor growth in CRC cells. Furthermore, we demonstrated that LZTS1 inhibited cell proliferation and tumor growth in CRC in part via suppression of AMT–mTOR, subsequently down-regulating p27Kip and up-regulating cyclin D1. These findings suggest that LZTS1 plays a potential tumor suppressor role in CRC progression and represents a valuable clinical prognostic marker of this disease.

Abstract 2464: Angiomotin plays a tumor suppressor role by sequestering oncogenic YAP/TAZ proteins and decreasing amphiregulin secretion in lung cancer

Abstract Lung cancer is the leading cause of cancer death worldwide, with metastasis underlying the majority of lung cancer-related deaths. Angiomotin (AMOT), a scaffold protein, has been shown to interact with oncogenic YAP/TAZ proteins, suggesting its potential role in tumor suppression. However, the functional role of AMOT in lung cancer remains unknown. We observed that the expression of AMOT was significantly decreased in clinical lung cancer specimens. Knockdown of AMOT in a low metastatic CL1-0 lung cancer cell line initiated cancer proliferation, migration, invasion and epithelial-mesenchymal transition. The trigger of cancer progression caused by AMOT loss was transduced by decreasing cytoplasmic sequestration and increasing nuclear translocation of oncogenic co-activators YAP/TAZ, resulting in an increased expression of the growth factor amphiregulin. The tumor promotion by AMOT knockdown was reversed when YAP/TAZ were absent or anti-amphiregulin antibodies were present. Further, AMOT knockdown increased the spread of Lewis lung carcinoma in vivo. Our findings suggest that AMOT is a crucial suppressor of lung cancer metastasis. These observations highlight the critical role of AMOT as a tumor suppressor, and the potential of AMOT as a prognostic biomarker and potential therapy target for lung cancer. Note: This abstract was not presented at the meeting. Citation Format: Po-Lin Kuo, Jen-Yu Hung, Ya-Ling Hsu. Angiomotin plays a tumor suppressor role by sequestering oncogenic YAP/TAZ proteins and decreasing amphiregulin secretion in lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2464. doi:10.1158/1538-7445.AM2014-2464

Long non‐coding RNA 91H contributes to the occurrence and progression of esophageal squamous cell carcinoma by inhibiting IGF2 expression

Long non-coding RNAs (lncRNAs) have been recently recognized as a major class of regulators in mammalian systems. 91H, a novel long noncoding antisense transcripts located on the position of the H19/IGF2 locus has been suggested to play a potential tumor-suppressor role in tumor development. However, little study has proved the mechanism in esophageal squamous cell carcinoma (ESCC). We carried out this study to explore the role of lncRNA 91H in the regulation of H19 imprinting control regions (ICR) and IGF2 expression and the association between 91H and ESCC progression. The cell line TE-1, Eca-109, and 232 ESCC patients' matched sets of paraffin-embedded adjacent normal and tumor samples were obtained in this study. The results showed that 91H expression was significantly lower in patients with higher depth of invasion, neoplastic grading and TNM which usually leads to the overexpression of IGF2 in tumor progression. The expression of 91H usually decreased in TE-1 and Eca-109 when treated with demethylation agent. Further analysis revealed that, in 91H knockdown cell lines, IGF2 expression was also significantly higher than negative controls. Therefore, the results demonstrated that the lncRNA 91H was associated with H19 ICR methylation and inhibited IGF2 expression of ESCC patients which may optimize the mechanism of IGF2 regulation in tumor development. Patients with higher depth of invasion, neoplastic grading and TNM usually demonstrated lower 91H expression potentially represent a novel clinically relevant event to identify individuals at increased risk for the occurrence, progression and prognosis of ESCC.

MicroRNA-147 Induces a Mesenchymal-To-Epithelial Transition (MET) and Reverses EGFR Inhibitor Resistance

BackgroundThe epithelial-mesenchymal transition (EMT) is a key developmental program that is often activated during cancer progression and may promote resistance to therapy. An analysis of patients (n = 71) profiled with both gene expression and a global microRNA assessment (∼415 miRs) identified miR-147 as highly anti-correlated with an EMT gene expression signature score and postulated to reverse EMT (MET).Methods and FindingsmiR-147 was transfected into colon cancer cells (HCT116, SW480) as well as lung cancer cells (A-549). The cells were assessed for morphological changes, and evaluated for effects on invasion, motility, and the expression of key EMT markers. Resistance to chemotherapy was evaluated by treating cells with gefitinib, an EGFR inhibitor. The downstream genes regulated by miR-147 were assayed using the Affymetrix GeneChip U133 Plus2.0 platform. miR-147 was identified to: 1. cause MET primarily by increasing the expression of CDH1 and decreasing that of ZEB1; 2. inhibit the invasion and motility of cells; 3. cause G1 arrest by up-regulating p27 and down-regulating cyclin D1. miR-147 also dramatically reversed the native drug resistance of the colon cancer cell line HCT116 to gefitinib. miR-147 significantly repressed Akt phosphorylation, and knockdown of Akt with siRNA induced MET. The morphologic effects of miR-147 on cells appear to be attenuated by TGF-B1, promoting a plastic and reversible transition between MET and EMT.ConclusionmiR-147 induced cancer cells to undergo MET and induced cell cycle arrest, suggesting a potential tumor suppressor role. miR-147 strikingly increased the sensitivity to EGFR inhibitor, gefitinib in cell with native resistance. We conclude that miR-147 might have therapeutic potential given its ability to inhibit proliferation, induce MET, as well as reverse drug sensitivity.

Evidence for Tumour Suppressor Function of DOK7 in Human Breast Cancer

Introduction: Downstream of tyrosine kinase 7 (DOK-7) is a member of the DOK family, which has been associated with the development and progression of various humancancers. Previously, identification of CpG hypermethylation in DOK-7 promoter was identified in breast cancer. Method: DOK-7 mRNA extraction and reverse transcription were performed on fresh frozen breast cancer tissue samples and normal background breast tissue. Transcript levels of expression were analyzed against TNM stage, tumour grade and clinical outcome over a 10-year follow-up period. Results: Levels of DOK-7 expression decreased significantly with increasing TNM stage. Higher DOK-7 expression was correlated with longer disease free and overall survival times. Conclusion: To our knowledge, this is the first study to investigate DOK-7 expression in human breast cancer. We identify a potential DOK-7 tumour suppressor role. DOK-7 as a prognostic biomarker in human breast cancer should be included in future validation studies.

The roles of miR-146a in the differentiation of Jurkat T-lymphoblasts

IntroductionT-cell acute lymphoblastic leukemia (T-ALL) is caused by a defect in T-cell maturation to the mature T cell. T-ALL is a poor prognostic hematopoietic malignancy. In order to establish a successful therapeutic treatment plan, it is essential to understand the biology of T-cell development and molecules that contribute to this process. This study uses Jurkat T cells, as a well-established model for in vitro study of T-ALL to investigate the role of the microRNA (miRNA), miR-146a, on gene expressions involved in T-cell differentiation.Materials and methodsThe permanent over-expression of miR-146a was established using a lentivector that expressed GFP hsa-mir-146a miRNA. We used quantitative real-time polymerase chain reaction and flow cytometry for T-cell differentiation to monitor induction of the differentiation process by assessing changes in expression of some distinct transcription factors and cell surface markers.ResultsEctopic expression of miR-146a resulted in significant up-regulation of PU.1, c-Fos, CCAAT/enhancer-binding protein alpha (C/EBPα) and GATA3, and slight up-regulation of Foxp3 and Runx1. There was a significant, moderate down-regulation in the expressions of Notch1, LIM-domain only (Lmo2), son of sevenless 1 (SOS1), Ikaros, and signal transducer and activator of transcription 3 (STAT3).ConclusionOur results indicated that ectopic expression of miR-146a could not independently induce differentiation in lymphoblastic cells. However, the expression of multiple genes involved in T-cell differentiation and T-cell CD markers were found to be affected. These results have suggested a potential tumor suppressive, immunomodulatory and cell activator role for miR146-a.

Abstract B127: Loss of miR-92 expression in breast epithelial cells is associated with cancer progression

Abstract MicroRNAs (miR) are a class of short non-coding RNAs that regulate gene expression and are commonly dysregulated in cancers, including those of the breast. MiR-92 is thought to function as an oncogene, promoting cell proliferation and reducing apoptosis. We have previously shown that expression of ERβ1 is negatively regulated by miR-92 in unselected non-microdissected breast cancers, providing a mechanism for down-regulation of this putative tumour suppressor gene. Here, we aimed to confirm the function of ERβ1 in breast cancer cells and examined expression of miR-92, specifically in the breast epithelium, during breast cancer progression. We also investigated the role of miR-92 in fibroblasts and examined whether differential expression in these cells might modify the behaviour of breast cancer epithelial cells. Stable ERβ1 overexpression was achieved using a MoMLV-based vector (pFBneo) or silenced by siRNA and effects were examined using various functional assays. We used laser microdissection (LMD) to isolate matched normal, co-incident DCIS and invasive tissue from 10 breast cancer patients. RNA was extracted, cDNA synthesised and preamplified using MegaPlex PreAmp Primers. MiR-92 expression was analysed by real-time PCR. Expression of ERβ1 protein was concurrently analysed for each patient by immunohistochemistry. LMD was also used to isolate matched normal and cancer-associated fibroblasts from 21 breast cancer patients and miR-92 expression was examined as above. Loss and gain of miR-92 in fibroblasts was achieved using anti-miR-92 miRNA and miRNASelect pEP-hsa-mir-92a-1 expression vector, respectively. The invasive potential of these fibroblasts was examined using a 2D modified Boyden chamber assay. ERβ1 overexpression decreased growth and induced cell death in T47D and BT-20 breast cancer cells. Surprisingly, we found that whilst absolute miR-92 expression levels varied across patients the expression pattern of miR-92 was consistent in all cases; miR-92 levels decreased during breast cancer progression with highest levels in normal breast epithelium, decreasing in DCIS (p&amp;lt;0.01) and lowest in invasive breast tissue (p&amp;lt;0.01). Expression of ERβ1 and miR-92 were not inversely correlated as expected. Further examination of the staining patterns of ERβ1 showed nuclear expression in normal breast epithelium with increased cytoplasmic immunoreactivity during progression to DCIS and invasive breast cancer. ERβ1 immunoreactivity was also seen in stromal fibroblasts in tissues, however miR-92 expression levels remained unchanged between matched microdissected adjacent normal and cancer-associated fibroblasts. Despite this, we demonstrated that fibroblasts can contribute to breast tumour progression as manipulation of miR-92 levels influenced the invasive potential of breast cancer epithelial cells. In summary, whilst confirming a potential tumour suppressor role for ERβ1 we have shown that expression is not inversely correlated with its negative regulator miR-92 in breast epithelium, suggesting other methods of regulation. Expression of miR-92 was lost, rather than gained, in breast epithelial cells during breast cancer progression correlating with a shift in ERβ1 staining from nuclei to the cytoplasm. While miR-92 expression levels remained unchanged in stromal fibroblasts, our data support a functional role in fibroblasts and show that differential miR-92 expression in these cells can influence the invasive capacity of breast cancer epithelial cells. Finally, our study highlights the importance of isolating specific cell types prior to expression analyses since changes in the epithelium may be masked by expression from the stroma and vice versa. Citation Format: Laura Smith, Euan Baxter, Andrew Hanby, Thomas Hughes, Rebecca Millican-Slater, Eldo Verghese, Valerie Speirs. Loss of miR-92 expression in breast epithelial cells is associated with cancer progression. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B127.

5S Ribosomal RNA Is an Essential Component of a Nascent Ribosomal Precursor Complex that Regulates the Hdm2-p53 Checkpoint

Recently, we demonstrated that RPL5 and RPL11 act in a mutually dependent manner to inhibit Hdm2 and stabilize p53 following impaired ribosome biogenesis. Given that RPL5 and RPL11 form a preribosomal complex with noncoding 5S ribosomal RNA (rRNA) and the three have been implicated in the p53 response, we reasoned they may be part of an Hdm2-inhibitory complex. Here, we show that small interfering RNAs directed against 5S rRNA have no effect on total or nascent levels of the noncoding rRNA, though they prevent the reported Hdm4 inhibition of p53. To achieve efficient inhibition of 5S rRNA synthesis, we targeted TFIIIA, a specific RNA polymerase III cofactor, which, like depletion of either RPL5 or RPL11, did not induce p53. Instead, 5S rRNA acts in a dependent manner with RPL5 and RPL11 to inhibit Hdm2 and stabilize p53. Moreover, depletion of any one of the three components abolished the binding of the other two to Hdm2, explaining their common dependence. Finally, we demonstrate that the RPL5/RPL11/5S rRNA preribosomal complex is redirected from assembly into nascent 60S ribosomes to Hdm2 inhibition as a consequence of impaired ribosome biogenesis. Thus, the activation of the Hdm2-inhibitory complex is not a passive but a regulated event, whose potential role in tumor suppression has been recently noted.

Ectopic expression of the TERE1 (UBIAD1) protein inhibits growth of renal clear cell carcinoma cells: Altered metabolic phenotype associated with reactive oxygen species, nitric oxide and SXR target genes involved in cholesterol and lipid metabolism

Current studies of the TERE1 (UBIAD1) protein emphasize its multifactorial influence on the cell, in part due to its broad sub-cellular distribution to mitochondria, endoplasmic reticulum and golgi. However, the profound effects of TERE1 relate to its prenyltransferase activity for synthesis of the bioactive quinones menaquinone and COQ10. Menaquinone (aka, vitamin K-2) serves multiple roles: as a carrier in mitochondrial electron transport, as a ligand for SXR nuclear hormone receptor activation, as a redox modulator, and as an alkylator of cellular targets. We initially described the TERE1 (UBIAD1) protein as a tumor suppressor based upon reduced expression in urological cancer specimens and the inhibition of growth of tumor cell lines/xenografts upon ectopic expression. To extend this potential tumor suppressor role for the TERE1 protein to renal cell carcinoma (RCC), we applied TERE1 immunohistochemistry to a TMA panel of 28 RCC lesions and determined that in 57% of RCC lesions, TERE1 expression was reduced (36%) or absent (21%). Ectopic TERE1 expression caused an 80% decrease in growth of Caki-1 and Caki-2 cell lines, a significantly decreased colony formation, and increased caspase 3/7 activity in a panel of RCC cell lines. Furthermore, TERE1 expression increased mitochondrial oxygen consumption and hydrogen production, oxidative stress and NO production. Based on the elevated cholesterol and altered metabolic phenotype of RCC, we also examined the effects of TERE1 and the interacting protein TBL2 on cellular cholesterol. Ectopic TERE1 or TBL2 expression in Caki-1, Caki-2 and HEK 293 cells reduced cholesterol by up to 40%. RT-PCR analysis determined that TERE1 activated several SXR targets known to regulate lipid metabolism, consistent with predictions based on its role in menaquinone synthesis. Loss of TERE1 may contribute to the altered lipid metabolic phenotype associated with progression in RCC via an uncoupling of ROS/RNS and SXR signaling from apoptosis by elevation of cholesterol.

Low expression of LOC285194 is associated with poor prognosis in colorectal cancer

BackgroundThe long non-coding RNAs (lncRNAs) study has gradually become one of the hot topics in the field of RNA biology. One lncRNA which has attracted attention is LOC285194, a lncRNA demonstrated the potential tumor-suppressor role in osteosarcoma. The aim of this study was to examine the expression of LOC285194 in colorectal cancer (CRC) patients and to investigate the relationship between this lncRNA levels and existing clinicopathologic parameters and patient survival.MethodsThe expression of LOC285194 was detected by quantitative real-time polymerase chain reaction in pairs of tumorous and adjacent normal tissues of 81 colorectal cancer patients with a follow-up of 5 years, as well as in three colorectal cancer cell lines and normal intestinal mucous cell line. Then, we analyzed the potential relationship between this lncRNA levels in tumor tissues and existing clinicopathological features of CRC, and clinical outcome.ResultsThe relative expression levels of LOC285194 was significantly lower in tumor tissues (p < 0.001) and colorectal cancer cell lines compared with adjacent normal tissues and normal intestinal mucous cell line. In addition, low expression of LOC285194 was correlated with larger tumor size (p = 0.015), higher tumor stage (p = 0.034), and more distant metastasis (p = 0.046). Kaplan-Meier analysis indicated that patients with low LOC285194 expression had a poor disease free survival (p = 0.010). Moreover, multivariate analysis showed that decreased expression of LOC285194 was an independent predictor of disease-specific survival.ConclusionOur data indicate that LOC285194 might be a novel prognostic indicator in colorectal cancer and may be a potential target for diagnosis and gene therapy.