Regulating Tumor Suppressor Genes Research Articles

P53 target ANKRA2 cooperates with RFX7 to regulate tumor suppressor genes

The transcription factor regulatory factor X 7 (RFX7) has been identified as a tumor suppressor that is recurrently mutated in lymphoid cancers and appears to be dysregulated in many other cancers. RFX7 is activated by the well-known tumor suppressor p53 and regulates several other known tumor suppressor genes. However, what other factors regulate RFX7 and its target genes remains unclear. Here, reporter gene assays were used to identify that RFX7 regulates the tumor suppressor gene PDCD4 through direct interaction with its X-box promoter motif. We utilized mass spectrometry to identify factors that bind to DNA together with RFX7. In addition to RFX7, we also identified RFX5, RFXAP, RFXANK, and ANKRA2 that bind to the X-box motif in the PDCD4 promoter. We demonstrate that ANKRA2 is a bona fide direct p53 target gene. We used transcriptome analyses in two cell systems to identify genes regulated by ANKRA2, its sibling RFXANK, and RFX7. These results revealed that ANKRA2 functions as a critical cofactor of RFX7, whereas RFXANK regulates largely distinct gene sets.

Abstract 5846: Inhibiting elements of the proteasome recovery pathway sensitizes glioblastoma to proteasome inhibitors

Abstract Bacground: Glioblastoma (GBM) is the most common primary brain tumor, accounting for 15% of all central nervous system related tumors. Despite the aggressive standard of care treatment including chemotherapy, radiotherapy, and maximally safe surgical resection, patient outcomes are abysmal: with 95% of patients relapsing and a median overall survival of 15 months. Thus, this necessitates the rapid query for personalized therapeutics and agents that can potentiate the clinical effects of currently approved treatments. One such pathway that demonstrates aberrant functioning in cancer and is a targetable mechanism is the ubiquitin-proteosome pathway (UPP). Studies have shown that UPP related proteolysis remains constitutively active in cancer cells leading to the rapid degradation of proteins that regulate tumor suppressor genes and oncogenes. Despite robust preclinical evaluations for the usage of proteosome inhibitors against GBM, most tested proteosome inhibitors failed in phase II and III trials, indicating resistance. Methods: We conducted an unbiased genome wide CRISPR-Cas9 screen in human HAP1 cells treated with the proteosome inhibitor, Bortezomib (BTZ), to identify genes that may lead to a BTZ-resistant phenotype. We identified several genes that when perturbed, sensitized cells to BTZ including N-glycanase-1 (NGLY-1), Nuclear factor Erythroid 2-Like-1 (NFE2L1), and DNA damage inducible 1 homolog 2 (DDI2). Herein we sought to evaluate the effects of perturbing components of the proteosome rescue pathway in our Singh lab patient derived GBM cell lines by utilizing CRISPR/Cas9 knockout technology in vitro and in vivo. Results: The generation of NGLY-1, DDI2, and NFE2L1 KO cell lines demonstrated functional sensitivity to the proteosome inhibitor Marizomib (MZB) as observed through a significant reduction of the IC50 in the KO cell lines compared to a control. Functional evaluation also revealed a reduction in proliferation capacity as well as sphere formation in these genetically modified GBM lines. Ongoing in vivo work will aim to evaluate the mitigation of this resistant pathway in our NSG mouse models orthotopically transplanted with these patient derived KO cell lines. In an ongoing collaborative effort, we are working to identify and functionally assess a novel small molecule NGLY-1 inhibitor to evaluate preclinical sensitivity to MZB in our in vitro and in vivo models. Citation Format: Alisha Anand, Muhammad Vaseem Shaikh, Chirayu Chokshi, Benjamin Brakel, William Maich, Shan Grewal, Chitra Venugopal, Sheila Singh. Inhibiting elements of the proteasome recovery pathway sensitizes glioblastoma to proteasome inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5846.

Analysis of microRNA regulating cell cycle-related tumor suppressor genes in endometrial cancer patients

Endometrial cancer remains the most common malignancy of the female genital system in developed countries. Tumor suppressor genes are responsible for controlling the cells fate in the cell cycle and preventing cancerogenesis. Gene expression affects cancer progression and is modulated by microRNAs defined as both tumor suppressors and oncogenes. These molecules indirectly regulate multiple processes like cell proliferation, differentiation and apoptosis. The aim of this study was to analyze miRNAs expression that can regulate the activity of tumor suppressor genes related to the cell cycle in patients with endometrioid endometrial cancer. The study group consisted of 12 samples that met the inclusion criteria from a total of 48 obtained. The 12 samples were used to analyze microRNA expression. Complementary miRNAs were identified using TargetScan Database and statistical analysis. MicroRNAs were determined for the tumor suppressor genes: CYR61, WT1, TSPYL5, HNRNPA0, BCL2L1 and BAK1. All the miRNAs were complementary to the described target genes based on TargetScan Database. There were five miRNAs differentially expressed that can regulate tumor suppressor genes related to the cell cycle. The distinguished miRNAs: mir-340-3p, mir-1236-5p, mir-874-3p, mir-873-5p.2 and mir-548-5p were differentially expressed in endometrial cancer in comparison to the control. Among the distinguished miRNAs, the most promising is mir-874-3p, which may have an important role in endometrial adenocarcinoma proliferation.

Design, synthesis, and characterization of α, β-unsaturated carboxylic acid, and its urea based derivatives that explores novel epigenetic modulators in human non-small cell lung cancer A549 cell line.

Histone deacetylase inhibitors (HDACi) are a small molecule chemotherapeutics that target the chromatin remodeling through the regulation of histone and non-histone proteins. These inhibitors directed against histone deacetylase (HDAC) enzymes have become an important therapeutic tool in oncology; consequently, scientific efforts have fortified the quest for newer and novel HDACi, which forces the design of structurally innovative HDACi. Various urea containing compounds exhibited admirable anticancer activity. On the basis of these observations, we design and synthesize HDAC specific blocker molecules which are specifically besieged towards class I, class II, and class IV HDAC isoforms to enhance the structural assortment for HDACi. Through docking experiments, we identified that the compounds were tightly bound to the isoforms of the HDAC enzymes at their receptor regions. These derivatives potently inhibited the different isoforms, namely, class I, II, and IV of HDACs, by hyperacetylation of lysine residues in A549 cells. The mechanism of apoptosis is evident, regulating tumor suppressor genes and proteins, thereby facilitating the activation of the death receptor pathway by the tumor necrosis factor (TNF) receptor. These derivative facilitated the induction of reactive oxygen species (ROS) generation leading to downregulation of Bcl2 , and upregulation of Bax expression, thereby dysregulating mitochondrial membrane potential (ΔΨm ) to release cytochrome c, and activation of intrinsic pathway. These compounds downregulate the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway to inhibit cell growth, proliferation, and metastasis through the matrix metalloproteinases (MMPs) MMP2 and MMP9 in A549 cells. These results suggest that our designed urea based derivatives act as epigenetic targeting agents through HDAC inhibition.

Association of miR-196a2 rs11614913 and miR-499 rs3746444 polymorphisms with cancer risk: a meta-analysis.

BackgroundMicroRNAs (miRNAs) are small non-coding RNA molecules, which participate in diverse biological processes and may regulate tumor suppressor genes or oncogenes. Rs11614913 in miR-196a2 and rs3746444 in miR-499 are shown to associate with increased/decreased cancer risk. This meta-analysis was performed to systematically assess the overall association.Materials and MethodsWe searched Pubmed, Web of Knowledge, EMBASE, Chinese National Knowledge Infrastructure (CNKI) databases until December 2016 to identify eligible studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of the associations.ResultsWe assessed published studies of the association between these microRNA polymorphisms and cancer risk from 56 studies with 21958/26436 cases/controls for miR-196a2 and from 37 studies with 13759/17946 cases/controls for miR-499. The results demonstrated that miR-196a2 rs11614913 was significantly associated with a decreased cancer risk, in particular with a decreased risk for colorectal cancer and gastric cancer, or for Asian population subgroup. In addition, miR-499 rs3746444 polymorphism was observed as a risk factor for cancers, in particular, for breast cancer, or for in the Asian population.ConclusionsOur meta-analysis suggests that the rs11614913 most likely contributes to decreased susceptibility to cancer, especially in Asians and colorectal cancer and gastric cancer, and that the rs3746444 may increase risk for cancer. Furthermore, more well-designed studies with large sample size are still necessary to further elucidate the association between polymorphisms and different kinds of cancers risk.

Effects of Atrial Natriuretic Peptide on p53 and Estrogen Receptor in Breast Cancer Cells.

The atrial natriuretic peptide (ANP) hormone is secreted by cardiac atrial myocytes and acts to regulate blood pressure homeostasis in humans. Previous research indicates ANP treatment significantly decreases the proliferation of human prostate cancer cells, pancreatic adenocarcinoma, and breast cancer cells. Minimal studies have been conducted with regard to ANP regulating tumor suppressor genes and steroid hormone receptors in breast cancer cells. Our study analyzed the effects of ANP in combination with 17β-estradiol (E2) and antiestrogen treatments on p53 and ERα levels in T-47D breast cancer cells. Preliminary studies through Western blot analysis showed that ANP treatment decreases p53 and ERα expression levels in a concentration-dependent (10–100 nM) manner. Treatment with ANP alone, at a 100 nM concentration, causes a decrease of p53 and ERα expression compared with Cs (control stripped), but with E2 and antiestrogen combinations, expression of both protein levels decreased compared with treatments without ANP. Combined treatment with E2, an estrogen antagonist, and ANP decreased cellular proliferation compared with treatments without ANP, except in the case of raloxifene (RAL). Our studies indicate that ANP has potential as a therapeutic breast cancer treatment and should inspire further studies on the molecular mechanism of ANP in T-47D breast cancer cells.

MiR-26a downregulates retinoblastoma in colorectal cancer.

MicroRNAs are non-coding short RNAs that target the 3' untranslated region of messenger RNAs (mRNAs) and lead to their degradation or to translational repression. Several microRNAs have been designated as oncomirs, owing to their regulating tumor suppressor genes. Interestingly, a few of them have been found to target multiple genes whose simultaneous suppression contributes to the development of a tumoral phenotype. Here, we have showed that miR-26a is overexpressed in colorectal cancer data obtained from TCGA Research Network and in human colon cancer pathological specimens; moreover, an orthotopic in vivo model of colon cancer showed overexpression of miR-26a, while Rb1 expression inversely correlated to miR-26a in TCGA Research Network data, pathological samples, and the in vivo model. Then, by means of luciferase assay, we demonstrated that miR-26a targets the 3' untranslated region of Rb1 mRNA directly. This is, to our knowledge, the first report of miR-26a targeting Rb1 in colon cancer. The results of this study suggested that miR-26a could serve as a progression biomarker in colorectal cancer. Further validation studies are still needed to confirm our findings.

Abstract 3119: miR-296-5p and miR-874-3p control cell proliferation and apoptosis in HCC via regulation of PIN1 expression

Abstract Introduction: PIN1 is a peptidyl-prolyl cis/trans isomerase (PPlase) that regulates multiple signaling pathways to control cell fate. It is found to be up-regulated in hepatocellular carcinomas (HCC), leading to increased cell proliferation and inhibition of apoptosis. However, the regulation of PIN1 remains poorly defined. MicroRNA (miRNA) plays a pivotal role in carcinogenesis by regulating tumor suppressor genes and oncogenes via targeting the 3′UTR of their encoded mRNAs. Therefore, we aimed at identifying miRNAs regulating PIN1 expression, and determining the contributions of these miRNAs to tumorigenesis through PIN1. Methods: Potential miRNAs regulating PIN1 were identified through sequence prediction using the online database TargetScan Release 6.2. Western immunoblotting and qRT-PCR were used to assess PIN1 expression in HCC cells with over-expression of identified miRNAs. Dual-Luciferase reporter assay was conducted to examine the direct interaction between the identified miRNAs and PIN1 3′UTR. The tumor suppressive role of the identified miRNAs in HCC cells was investigated using MTT cell proliferation assay, colony formation assay and Annexin V apoptosis detection assay. To investigate the correlation between the levels of PIN1 and the identified miRNAs, qRT-PCR was used to determine the mRNA levels of PIN1 and the identified miRNAs in 20 pairs of normal liver tissue and HCC. Results: We identified miR-296-5p and miR-874-3p as important negative regulators of PIN1. Consequently, over-expression of miR-296-5p and miR-874-3p enhanced cellular apoptosis, and inhibited cell growth and colony formation in HCC cells. Furthermore, the cellular functions of miR-296-5p and miR-874-3p were abrogated by over-expression of PIN1. Importantly, the expression of PIN1 was negatively correlated with that of miR-296-5p and miR-874-3p in HCC tissues, consistent with the regulatory role of miR-295-5p and miR-874-3p on PIN1 expression. Conclusion: Taken together, our data showed that miR-296-5p and miR-874-3p controlled cell proliferation and apoptosis in HCC by regulating PIN1 expression. Citation Format: Ka Wai Leong, Chi Wai Cheng, Chun Ming Wong, Oi Lin Irene Ng, Yok Lam Kwong, Eric Wai Choi Tse. miR-296-5p and miR-874-3p control cell proliferation and apoptosis in HCC via regulation of PIN1 expression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3119. doi:10.1158/1538-7445.AM2015-3119

Abstract 5228: Characterization of miR-21 as a potential circulating biomarker for osteosarcoma

Abstract MicroRNAs (miRNAs) are a class of small noncoding RNAs that are implicated in various important biological processes by regulation of gene expression. Aberrant miRNA expression is suggested to be associated with various human disorders including cancer. In this study, we studied if miRNAs can be used as biomarkers in osteosarcoma (OS). OS is the most common malignant bone tumor in children and young adults. Despite the use of surgery and multi-agent chemotherapy, OS patients who respond poorly towards chemotherapy or develop relapses have a dismal outcome. Thus, it is of clinical significance if a biomarker approach can be developed to monitor tumor burden and detect early relapses in the patients, so that they can be treated as early as possible to improve the survival. To achieve this goal, we performed miRNA profiling on a cohort of OS plasma samples collected from the Texas Children's Hospital. miR-21 and other miRNAs were identified to be elevated in OS patients relative to a group of healthy controls. Circulating miR-21 has been detected in other types of cancer and in the tumor it is known to negatively regulate tumor suppressor genes involved in proliferation, apoptosis and invasion; however, its role in OS is still unclear. Hence, we first validated that miR-21 was elevated in a set of independent osteosarcoma plasma samples but not in the control samples. Using serial plasma samples from a group of patients, we found that the circulating miR-21 level was lower in the posttreatment plasma samples than in the pretreatment samples. These results suggest that circulating miR-21 may correlate with tumor burden of the patients. In addition, miR-21 was expressed in many OS tumors as detected by in situ hybridization on an OS tissue microarray. When tested on two OS cell lines, miR-21was significantly increased in the culture media between 24 and 48 hours after plating in a cell number dependent manner, suggesting that miR-21 could be released from the tumor cells. Taken together, our results suggest that miR-21 is expressed in OS and its level in plasma may reflect tumor burden in OS patients. Citation Format: Manjula Nakka, Yiting Li, Colin McGee, Ching Lau, Tsz Kwong Man. Characterization of miR-21 as a potential circulating biomarker for osteosarcoma. [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 5228. doi:10.1158/1538-7445.AM2014-5228

Quantitative assessment of the association between miR-196a2 rs11614913 polymorphism and cancer risk: evidence based on 45,816 subjects

MicroRNAs (miRNAs) are small non-coding RNA molecules, which participate in diverse biological processes and may regulate tumor suppressor genes or oncogenes. Single nucleotide polymorphisms (SNPs) in miRNA may contribute to diverse functional consequences, including cancer development, by altering miRNA expression. Numerous studies have shown the association between miR-196a2 rs11614913 SNPs and cancer risk; however, the results are generally debatable and inconclusive, mainly due to limited statistical power. We carried out a meta-analysis of 46 studies including 20,673 cases and 25,143 controls to assess the association between the miR-196a2 rs11614913 and cancer risk by pooled odds ratios (ORs) and 95 % confidence intervals (CIs). Overall, we found a significant association between the rs11614913 (C > T) polymorphism and cancer susceptibility (recessive model, OR = 0.89, 95 % CI = 0.81-0.98). In the stratified analysis by cancer type, significant association of cancer risk was observed in lung cancer (allelic contrast, OR = 0.89, 95 % CI = 0.82-0.97; homozygote comparison, OR = 0.79, 95 % CI = 0.67-0.94; recessive model, OR = 0.84, 95 % CI = 0.74-0.96) and liver cancer (allelic contrast, OR = 0.88, 95 % CI = 0.79-0.99; homozygote comparison, OR = 0.77, 95 % CI = 0.61-0.98; heterozygote comparison, OR = 0.84, 95 % CI = 0.74-0.95; dominant model, OR = 0.82, 95 % CI = 0.73-0.92). During further stratified analysis by ethnicity, the rs11614913 polymorphism showed statistically significant association with increased risks of cancer in Asians (heterozygote model, OR = 1.15, 95 % CI = 1.01-1.30) but not in Caucasians. This meta-analysis suggests that the miR-196a2 rs11614913 polymorphism may contribute to decreased susceptibility to cancer, especially including liver cancer and lung cancer. However, it may be a risk factor for cancer development in Asians. Larger, better studies of homogeneous cancer patients are needed to further assess the correlation between this polymorphism and cancer risk.

Association between microRNA Polymorphisms and Cancer Risk Based on the Findings of 66 Case-Control Studies

MicroRNAs (miRNAs) are small non-coding RNA molecules, which participate in diverse biological processes and may regulate tumor suppressor genes or oncogenes. Single nucleotide polymorphisms (SNPs) in miRNA may contribute to diverse functional consequences, including cancer development, by altering miRNA expression. Numerous studies have shown the association between miRNA SNPs and cancer risk; however, the results are generally debatable and inconclusive, mainly due to limited statistical power. To assess the relationship between the five most common SNPs (miR-146a rs2910164, miR-196a2 rs11614913, miR-499 rs3746444, miR-149 rs2292832, and miR-27a rs895919) and the risk cancer development, we performed a meta-analysis of 66 published case-control studies. Crude odds ratios at 95% confidence intervals were used to investigate the strength of the association. No association was observed between rs2910164 and cancer risk in the overall group. However, in stratified analysis, we found that either the rs2910164 C allele or the CC genotype was protective against bladder cancer, prostate cancer, cervical cancer, and colorectal cancer, whereas it was a risk factor for papillary thyroid carcinoma and squamous cell carcinoma of the head and neck (SCCHN). Further, rs11614913 was found to be significantly associated with decreased cancer risk, in particular, for bladder cancer, gastric cancer, and SCCHN. For miR-499, a significant association was found between the rs3746444 polymorphism and cancer risk in pooled analysis. In subgroup analysis, similar results were mainly observed for breast cancer. Finally, no association was found between rs2292832 and rs895919 polymorphisms and cancer risk in the overall group and in stratified analysis. In summary, miR-196a2 rs11614913, miR-146a rs2910164, and miR-499 rs3746444 are risk factors for cancer development, whereas mir-149 rs2292832 and miR-27a rs895919 are not associated with cancer risk.

MicroRNA187 overexpression is related to tumor progression and determines sensitivity to bortezomib in peripheral T-cell lymphoma

MicroRNAs (miRs) are involved in tumorigenesis by regulating tumor suppressor genes and/or oncogenes. MiR187 was overexpressed in peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) and associated with high Ki67 expression, elevated lactate dehydrogenase, advanced International Prognostic Index and poor prognosis of patients. In vitro, ectopic expression of miR187 in T-lymphoma cell lines accelerated tumor cell proliferation, whereas treatment with miR187 inhibitor reduced cell growth. MiR187 downregulated tumor suppressor gene disabled homolog-2 (Dab2), decreased the interaction of Dab2 with adapter protein Grb2, resulting in Ras activation, phosphorylation/activation of extracellular signal-regulated kinase (ERK) and AKT, and subsequent stabilization of MYC oncoprotein. MiR187-overexpressing cells were resistant to chemotherapeutic agents like doxorubicin, cyclophosphamide, cisplatin and gemcitabine, but sensitive to the proteasome inhibitor bortezomib. Bortezomib inhibited T-lymphoma cell proliferation by downregulating miR187, dephosphorylating ERK and AKT and degrading MYC. In a murine xenograft model established with subcutaneous injection of Jurkat cells, bortezomib particularly retarded the growth of miR187-overexpressing tumors, consistent with the downregulation of miR187, Ki67 and MYC expression. Collectively, these findings indicated that miR187 was related to tumor progression in PTCL-NOS through modulating Ras-mediated ERK/AKT/MYC axis. Although potentially oncogenic, miR187 indicated the sensitivity of T-lymphoma cells to bortezomib. Cooperatively targeting ERK and AKT could be a promising clinical strategy in treating MYC-driven lymphoid malignancies.

Identification of colorectal cancer recurrence-related microRNAs

Colorectal cancer (CRC) has high recurrence rate.Effective biomarkers for the detection of colon cancer are still unavailable. MicroRNA (miRNA) is an epigenetic factor that regulates cell proliferation, tumor cell growth, cancer formation, and metastasis by regulating tumor suppressor genes or oncogenes. miRNA has the potential to be used as a biomarker for the diagnosis of diverse cancers. Previously, we revealed that miR-139-3 p is downregulated and miR-338-5 p is upregulated in recurrent CRC patients. The present study further reveals that the miR-139-3 p expression level is inversely correlated with increased metastatic status in three colon cancer cell lines (SW480, SW620, and colo201), as determined using real-time polymerase chain reaction. Furthermore, in 51 pairs of CRC clinical specimens, the expression level of mir-139-3 p was significantly lower in the tumor sections than in the adjacent normal tissues (p < 0.0001), indicating that they are tumor-suppressive miRNAs. Furthermore, the expression level of mir-338-5 p in the tumor tissues of metastatic patients was significantly higher than in the tumor tissues of nonmetastatic patients (p < 0.05), indicating that mir-338-5 p is positively correlated with metastasis. All together, mir-139-3 p and mir-338-5 p may have potential use as biomarkers for the diagnosis of tumor formation and metastasis in CRC patients.

Cancer Regulator MicroRNA: Potential Relevance in Diagnosis, Prognosis and Treatment of Cancer

MicroRNAs (miRNAs) are small (typically 22 nucleotides) non-coding, endogenous, single-stranded RNAs. MiRNA genes are evolutionarily conserved and are located within the introns or exons of protein-coding genes, as well as in intergenic areas. Before the discovery of miRNAs, it had been known that a large part of the genome is not translated into proteins. This so called "junk" DNA was thought to be evolution debris with no function. Recently, the explosive research in this area has established miRNAs as powerful regulators of gene expression. While only about 1,424 human miRNA sequences have been identified so far, genomic computational analysis indicates that as many as 50,000 miRNAs may exist in the human genome, and each may have multiple targets based on similar sequences in the 3'-UTR of mRNA. MiRNAs have been implicated in different areas such as the immune response, neural development, DNA repair, apoptosis, oxidative stress response and others and it is impressive the list of diseases which have recently been found to be associated with abnormal miRNA expression. Here, we focus our attention on the importance of cancer regulator miRNAs. They are divided into oncomiRs and anti-oncomiRs that negatively regulate tumor suppressor genes and oncogenes, respectively. Importantly, the association of miRNAs with cancer has prompted additional functional classification of these short RNAs and their potential relevance in cancer diagnosis, prognosis and treatment.

Molecular imaging of a cancer-targeting theragnostics probe using a nucleolin aptamer- and microRNA-221 molecular beacon-conjugated nanoparticle

MicroRNAs (miRNA, miR) have been reported as cancer biomarkers that regulate tumor suppressor genes. Hence, simultaneous detecting and inhibiting of miRNA function will be useful as a cancer theragnostics probe to minimize side effects and invasiveness. In this study, we developed a cancer-targeting therangostics probe in a single system using an AS1411 aptamer - and miRNA-221 molecular beacon (miR-221 MB)-conjugated magnetic fluorescence (MF) nanoparticle (MFAS miR-221 MB) to simultaneously target to cancer tissue, image intracellularly expressed miRNA-221 and treat miRNA-221-involved carcinogenesis. AS1411 aptamer-conjugated MF (MFAS) nanoparticles displayed a great selectivity and delivery into various cancer cell lines. The miR-221 MB detached from the MFAS miR-221 MB in the cytoplasm of C6 cells clearly imaged miRNA-221 biogenesis and simultaneously resulted in antitumor therapeutic effects by inhibiting miRNA function, indicating a successful astrocytoma-targeting theragnostics. MFAS miRNA MB can be easily applied to other cancers by simply changing a targeted miRNA highly expressed in cancers.

Abstract 123: miR-145 function as a tumor suppressor targeting multiple oncogenes in prostate cancer

Abstract Prostate cancer remains one of the most prevalent cancers and a major cause of morbidity and mortality in the western world. Disease progression and the development of hormone refractory disease remain major causes of cancer-related death. The understanding of the new molecular pathways of hormone refractory would be helpful in improving diagnosis and therapy of the disease. microRNAs (miRNAs) are small, non-coding RNAs with a length of approximately 22 nucleotides. They regulate gene expression by promoting mRNA cleavage and at the posttranscriptional level by translational suppression. They play important roles in various biological and metabolic processes, including development, differentiation, signal transduction, cell maintenance, and cancer. Bioinformatic predictions indicate that miRNAs regulate more than 30% of the protein coding genes. It is estimated that approximately 1,000 miRNAs exist in the vertebrate genome. An important role for miRNAs in the development of cancer has emerged in recent years. miRNAs are aberrantly expressed in many human cancers, and they may function as oncogenes or tumor suppressors. Up-regulated miRNAs could function as oncogenes by negatively regulating tumor suppressor genes, while down-regulated miRNAs could act as tumor suppressors, inhibiting cancers by regulating oncogenes. Down-regulation of miR-145 has been reported in many types of human cancer, including prostate cancer, suggesting that miR-145 function as a tumor suppressor. In this study, we focused on target identification of miR-145 in prostate cancer, based on gene-wide gene expression analysis of miR-145 transfection cells. According to our expression analysis showed that down-regulated genes (FSCN1, UNG and EIF4EBP2) were identified. Loss-of-function assays revealed that FSCN1 inhibited cell proliferation, migration, and invasion in PC3 and DU145 cells, suggesting FSCN1 function as an oncogene. The identification of tumor suppressive miRNA and their target genes could provide new insights into potential mechanisms of prostate carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 123. doi:10.1158/1538-7445.AM2011-123

Gene Expression Profiling Identifies WNT7A As a Possible Candidate Gene for Decreased Cancer Risk in Fragile X Syndrome Patients

Although sporadic cases of cancer in patients with fragile X syndrome (FXS) have been reported, extensive studies carried out in Denmark and Finland concluded that cancer incidence in these patients is lower than in the general population. On the other hand, the FMR1 protein, which is involved in the translation process, is absent in FXS patients. Hence, it is reasonable to assume that these patients exhibit an abnormal expression of some proteins involved in regulating tumor suppressor genes and/or oncogenes, thus explaining its decreased cancer frequency. We undertook this study to analyze the expression of oncogenes and tumor suppressor genes in fragile X syndrome patients. Molecular analysis of the FMR1 gene was achieved in 10 male patients and controls. Total RNA from peripheral blood was used to evaluate expression of oncogenes and tumor suppressor genes included in a 10,000 gene microarray library. Quantitative real-time PCR was utilized to confirm genes with differential expression. Among 27 genes showing increased expression in FXS patients, only eight genes exhibited upregulation in at least 50% of them. Among these, ARMCX2 and PPP2R5C genes are tumor suppressor related. Likewise, 23/65 genes showed decreased expression in >50% of patients. Among them, WNT7A gene is a ligand of the beta-catenin pathway, which is widely related to oncogenic processes. Decreased expression of WNT7A was confirmed by quantitative RT-PCR. Expression of c-Myc, c-Jun, cyclin-D and PPARdelta genes, as target of the beta-catenin pathway, was moderately reduced in FXS patients. Results suggest that this diminished expression of the WNT7A gene may be related to a supposed protection of FXS patients to develop cancer.

PPARγ and PPARδ as Modulators of Neoplasia and Cell Fate

PPARγ and PPARδ agonists represent unique classes of drugs that act through their ability to modulate gene transcription associated with intermediary metabolism, differentiation, tumor suppression, and in some instances proliferation and cell adhesion. PPARγ agonists are used by millions of people each year to treat type 2 diabetes but may also find additional utility as relatively nontoxic potentiators of chemotherapy. PPARδ agonists produce complex actions as shown by their tumor promoting effects in rodents and their cholesterol-lowering action in dyslipidemias. There is now emerging evidence that PPARs regulate tumor suppressor genes and developmental pathways associated with transformation and cell fate determination. This review discusses the role of PPARγ and PPARδ agonists as modulators of these processes.