Differential Expression of miRNAs in Papillary Thyroid Carcinoma Compared to Multinodular Goiter Using Formalin Fixed Paraffin Embedded Tissues

microRNAs (miRNAs) are approximately 22 nt RNAs that negatively regulate target gene expression. Their dysregulation has been implicated in the pathogenesis of a number of human cancers, including papillary thyroid carcinoma (PTC). Whereas previous studies using microarray technologies have largely relied on the ability to procure fresh tissue at the time of surgery to characterize miRNA signatures in PTC, we exploited the ability to procure sufficient miRNA from formalin-fixed paraffin-embedded (FFPE) tissue to describe a series of miRNAs whose expression is dysregulated in PTC compared to benign proliferative multinodular goiter (MNG). We identified 13 miRNAs upregulated and 26 miRNAs downregulated in PTC versus MNG. These include miRNA-21, miRNA-31, miRNA-221, and miRNA-222. Their dysregulation was further validated by real time RT-PCR analysis in an independent set of FFPE tissues. Many of these have previously been described in fresh tissue studies as altered in PTC, confirming the utility of this approach. These results further highlight the applicability of miRNA expression patterns as potential markers of human cancer, and our results suggest that FFPE tissues are suitable resources for such miRNA expression analyses. The ability to utilize FFPE tissue in the molecular characterization of human malignancy will unlock a rich resource for future cancer studies. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Methods and matrices: approaches to identifying miRNAs for Nasopharyngeal carcinoma

Background

Nasopharyngeal carcinoma (NPC) is a solid tumor of the head and neck. Multimodal therapy is highly effective when NPC is detected early. However, due to the location of the tumor and the absence of clinical signs, early detection is difficult, making a biomarker for the early detection of NPC a priority. The dysregulation of small non-coding RNAs (miRNAs) during carcinogenesis is the focus of much current biomarker research. Herein, we examine several miRNA discovery methods using two sample matrices to identify circulating miRNAs (c-miRNAs) associated with NPC.

Methods

We tested two miRNA discovery workflows on two sample sources for miRNAs associated with NPC. In the first workflow, we assumed that NPC tumor tissue would be enriched for miRNAs, so we compared miRNA expression in FFPE from NPC cases and controls using microarray and RNA-Seq technologies. Candidate miRNAs from both technologies were verified by qPCR in FFPE and sera from an independent NPC sample set. In a second workflow, we directly interrogated NPC case and control sera by RNA-Seq for c-miRNAs associated with NPC, with candidate c-miRNAs verified by qPCR in the sera from the same independent NPC sample set.

Results

Both microarray and RNA-Seq narrowed the miRNA signature to 1-5% of the known mature human miRNAs. Moreover, these two methods produced similar results when applied to the same sample type (FFPE), with RNA-Seq additionally indicating “unknown” miRNAs associated with NPC. However, we found different miRNA profiles in NPC sera compared to FFPE using RNA-Seq, with the few overlapping miRNAs found to be significantly up-regulated in FFPE significantly down-regulated in sera (and vice versa). Despite the different miRNA profiles found in FFPE and sera, both profiles strongly associated with NPC, providing two potential sources for biomarker signatures for NPC.

Conclusions

We determined that the direct interrogation of sera by RNA-Seq was the most informative method for identifying a c-miRNA signature associated with NPC. We also showed that there are different miRNA expression profiles associated with NPC for tumor tissue and sera. These results reflect on the methods and meaning of miRNA biomarkers for NPC in tissue and peripheral blood.     

Differential Expression Profiling and Functional Analysis of microRNAs through Stage I-III Papillary Thyroid Carcinoma

Objective: To elucidate the mechanisms undergoing the pathogenesis of PTC, this study try to find stage specific microRNAs (miRNAs) using microarray chip in stage I, II and III papillary thyroid carcinoma (PTC) tissues as well predict miRNAs binding target genes and their molecular functions.Methods: PTC specimens of stage I, II, and III and their paired adjacent non-tumor tissue (one patient for each stage) were collected. The expressions of miRNAs were examined using miRNA microarray chip. The most significant changed miRNAs from microarray were verified by using quantitative RT-PCR. The Potential miRNAs regulating target genes and their preliminary biological functions were forecasted with variety function prediction software.Results: Ten miRNAs exhibited sequential up regulation expression profiles and five miRNAs performed sequential down regulation throughout stage I to III (p<0.05). After normalization, Fifteen miRNAs showed significant different compared to adjacent non-tumor tissues (p<0.05). Among of them, the most significant up regulation and down regulation miRNAs were miR-146b-5p and miR-335, respectively. Both of them were verified with qRT-PCR. 34 target genes for miR-146-5p and 36 target genes for miR-335 was predicted.Conclusion: MicroRNA profile assay successfully detected a branch of differential expression miRNAs between PTC and normal tissue. Some of them also showed stage specific. Biological function analysis showed that target genes were involved in five aspects including cell proliferation, differentiation, apoptosis, cycle, and signaling transduction pathway, suggesting the regulatory role of abnormal expression of critical miRNAs in the pathogenesis of PTC.     

MicroRNA Microarray Expression Profiling in Human Myocardial Infarction

MicroRNAs (miRNAs), small non-coding RNA molecules, are negative regulators of gene expression. Recent studies have indicated their role in various forms of cardiovascular disease. In spite of the number of miRNA microarray analyses performed, little is known about the genome-wide miRNA expression pattern in human myocardial infarction (MI). Using miRNA microarrays and bioinformatic analysis, miRNA expression was analyzed on human MI and foetal hearts compared to healthy adult hearts, to determine whether there is any similar expression pattern between MI and foetal hearts, and to identified miRNAs that have not previously been described as dysregulated in cardiovascular diseases. Of 719 miRNAs analyzed, ∼ 50% were expressed in human hearts, 77 miRNAs were absent from all tested tissues and 57 were confidently dysregulated in at least one tested group. Some expression patterns appeared to be similar in MI and foetal hearts. Bioinformatic analysis revealed 10 miRNAs as dysregulated in MI not yet related to cardiovascular disease, and 5 miRNAs previously described only in animal models of cardiovascular diseases. Finally, qRT-PCR analysis confirmed dysregulation of 7 miRNAs, miR-150, miR-186, miR-210, miR-451, and muscle-specific, miR-1 and miR-133a/b; all of these are believed to be involved in various physiological and pathological processes.     

Profiling differential microRNA expression between in situ,infiltrative and lympho-vascular space invasive breast cancer: a pilot study

Ductal carcinoma in situ (DCIS), invasive breast cancer (IBC) and lympho-vascular invasion (LVI) represent distinct stages in breast cancer progression with different clinical implications. Altered microRNA (miRNA) expression may play a role in mediating the progression of DCIS to IBC and LVI. The aim of this pilot study was to investigate whether differential miRNA expression could play a role in breast cancer progression. Cancer cells from DCIS, IBC and LVI were microdissected from formalin fixed paraffin embedded (FFPE) tissue of five breast cancer samples. MiRNA profiling of extracted RNA was performed using the TaqMan^® Array Human MicroRNA Cards A and B v3.0. Candidate miRNAs and gene targets were validated by qPCR. 3D culture of MCF10A, MCF10DCIS.com and T47D cells were used as models for normal, DCIS and IBC. Immunohistochemistry of candidate genes was performed on FFPE 3D cell cultures as well as on tissue microarray which included cores of DCIS and IBC samples. MiR-150, miR-126 and miR-155 were found to be more highly expressed in IBC and LVI compared to DCIS. Gene targets of these miRNAs, RhoA, PEG10 and MYB, were found to be more highly expressed in DCIS compared to IBC by qPCR and in MCF10A and MCF10DCIS.com cells compared to T47D cells by immunohistochemistry. There was no difference in intensity of staining of RhoA by immunohistochemistry in DCIS versus IBC samples on tissue microarray. In this pilot study, we found evidence to support a potential role for variation in miRNA levels in the transition from DCIS to IBC.     

Comparison of ethanol versus formalin fixation on preservation of histology and RNA in laser capture microdissected brain tissues

Although RNA can be retrieved from formalin-fixed, paraffin-embedded (FFPE) tissues, the yield is low, and the RNA is fragmented. Recent advances in gene expression profiling underscore the importance of identifying a fixative that preserves histology and mRNA. We demonstrated that, for immersion fixation of brains, 70% ethanol is superior to formalin for mRNA preservation. RNA yield from ethanol-fixed tissues was 70% of the yield from fresh frozen specimens, but only a negligible quantity was recovered from formalin-fixed tissues. RNA from ethanol-fixed brains showed integrity comparable to RNA from fresh frozen tissues, and RT-PCR using RNA from ethanol-fixed tissues was consistently successful. RNA from FFPE tissues composed of low-molecular weight fragments, and their use in RT-PCR failed repeatedly. The yield and quality of RNA from ethanol-fixed brains were unaffected after immersion at 4 degrees C for 2 weeks. In a blinded comparison to FFPE tissues, ethanol-fixed specimens were judged to show comparable histology and superior immunostaining. After laser capture microdissection (LCM), we failed to recover mRNA from FFPE tissues but retrieved mRNA from ethanol-fixed tissues for RT-PCR and cDNA microarray analysis. We conclude that 70% ethanol preserves RNA integrity and is suitable for expression profiling of brain tissues by LCM and cDNA microarray.     

乳腺癌miRNAs表达谱的检测

目的检测人乳腺癌石蜡组织及人乳腺癌细胞株中miRNAs的表达情况,初步筛选人乳腺癌miRNAs表达谱。方法(1)应用组织微阵列平台,采用原位分子杂交技术对91例人乳腺癌和26例癌旁乳腺组织标本42种miRNA进行检测;(2)培养人乳腺癌细胞株MDA-MB-231和正常乳腺上皮细胞株HBL-100,分别抽提细胞总RNA,分离小分子RNA,荧光标记后与miRNAs微阵列杂交,通过芯片扫描和数据分析,获得人乳腺癌miRNAs表达谱。结果(1)与癌旁乳腺组织相比,14种miR-NAs在乳腺癌组织中的表达发生了显著变化(P0.05),其中9种表达上调,5种表达下调。(2)利用miRNAs微阵列,筛选获得71种与人乳腺癌相关miRNAs,与正常乳腺上皮细胞相比,34种miRNAs表达上调,37种表达下调。结论筛选出与乳腺癌相关的差异表达miRNAs,为进一步研究其在乳腺癌中的作用奠定基础。     

mRNA and micro-RNA expression analysis in laser-capture microdissected prostate biopsies: Valuable tool for risk assessment and prevention trials

Diagnosis of prostate cancer (PCa) typically relies on needle biopsies, which are routinely archived in paraffin after formalin fixation and may contain valuable risk or prognostic information. The objective of this study was to determine the feasibility of mRNA and miRNA expression analysis in laser-capture microdissected (LCM) formalin-fixed paraffin-embedded archived prostate biopsies compared to the gold standard of frozen tissue. We analyzed the expression of compartment-specific and PCa-related genes in epithelial and stromal tissues collected from paired sets of archived prostate biopsies and frozen radical prostatectomy specimens from three patients. Our results showed appropriate compartment-specific and PCa-related expression with good within patient agreement between the FFPE biopsies and the frozen tissue. The potential for both mRNA and micro-RNA expression profiling in the biopsies was also demonstrated using PCR arrays which showed high correlation between the biopsy and frozen tissue, notwithstanding sensitivity limitations for mRNA detection in the FFPE specimen. This is the first study to compare RNA expression from biopsy and frozen tissues from the same patient and to examine miRNA expression in LCM-collected tissue from prostate biopsies. With careful technique and use of appropriate controls, RNA profiling from archived biopsy material is quite feasible showing high correlation to frozen tissue.     

Limited tissue fixation times and whole genomic amplification do not impact array CGH profiles

BACKGROUND: Array comparative genomic hybridisation (CGH) is a powerful method for the genetic analysis of lesional and normal tissues to identify genomic imbalances associated with malignancies. However, the use of this technique with DNA extracted from archival formalin fixed, paraffin embedded (FFPE) tissue specimens, the most widely available resource for retrospective studies, is subject to quantitative and qualitative limitations. In this report, the suitability and integrity of the DNA extracted from FFPE MCF7 breast cancer cells fixed for different periods of time for array CGH applications were examined. RESULTS: Using our established cDNA microarray protocol in conjunction with whole genome amplification methods, the genetic profiles of freshly harvested MCF7 cells and their matched FFPE counterparts were analysed. Congruent profiles between FFPE MCF7 cells and their fresh counterpart and between amplified and non-amplified FFPE MCF7 cells were observed. Our results demonstrate that formalin fixation of <20 hours has no significant adverse effect on the integrity of DNA for array CGH studies. CONCLUSIONS: Our findings attest to the fidelity of our array CGH methods to effectively examine material recovered from FFPE tissue specimens for microarray applications. This in turn has great potential to identify novel diagnostic and prognostic markers for human disease.     

应用基因芯片检测喉鳞状细胞癌甲醛固定石蜡包埋组织microRNA表达谱

目的 建立以甲醛固定石蜡包埋组织为材料、基于基因芯片技术的microRNA(miRNA)表达谱的分析方法 ;筛选与喉鳞状细胞癌(简称喉癌)生物学特征密切相关的差异表达miRNA.方法 从喉癌甲醛固定石蜡包埋组织中制备总RNA,经质量鉴定后进行荧光标记.采用Agilent公司的容纳723条人类miRNA探针的基因芯片完成杂交实验,以获得喉癌的miRNA表达谱.以GeneSpring GX和R-Project软件处理分析基因芯片实验数据,筛选与喉癌转移相关的差异表达miRNA.结果 从24例甲醛固定石蜡包埋组织标本中获得了符合基因芯片实验质量标准的RNA样品,并完成了基因芯片杂交及数据分析.从中共鉴定到319个miRNA,有96个miRNA在24例喉癌中均有表达,其中与淋巴结转移密切相关的(检错率<0.05)差异表达miRNA有5个,分别为miR-23a* 、miR-28-5p、miR-15a、miR-16和miR-425.结论 甲醛固定石蜡包埋组织可以提供符合基因芯片分析质量要求的miRNA,是研究miRNA的重要样品资源.从喉癌的miRNA表达谱中筛选出的转移相关差异表达miRNA(miR-23a*、miR-28-5p、miR-15a、miR-16和miR-425)有可能成为评估喉癌转移风险的新型分子标志.     

应用基因芯片检测喉鳞状细胞癌甲醛固定石蜡包埋组织microRNA表达谱

目的 建立以甲醛固定石蜡包埋组织为材料、基于基因芯片技术的microRNA(miRNA)表达谱的分析方法 ;筛选与喉鳞状细胞癌(简称喉癌)生物学特征密切相关的差异表达miRNA.方法 从喉癌甲醛固定石蜡包埋组织中制备总RNA,经质量鉴定后进行荧光标记.采用Agilent公司的容纳723条人类miRNA探针的基因芯片完成杂交实验,以获得喉癌的miRNA表达谱.以GeneSpring GX和R-Project软件处理分析基因芯片实验数据,筛选与喉癌转移相关的差异表达miRNA.结果 从24例甲醛固定石蜡包埋组织标本中获得了符合基因芯片实验质量标准的RNA样品,并完成了基因芯片杂交及数据分析.从中共鉴定到319个miRNA,有96个miRNA在24例喉癌中均有表达,其中与淋巴结转移密切相关的(检错率<0.05)差异表达miRNA有5个,分别为miR-23a* 、miR-28-5p、miR-15a、miR-16和miR-425.结论 甲醛固定石蜡包埋组织可以提供符合基因芯片分析质量要求的miRNA,是研究miRNA的重要样品资源.从喉癌的miRNA表达谱中筛选出的转移相关差异表达miRNA(miR-23a*、miR-28-5p、miR-15a、miR-16和miR-425)有可能成为评估喉癌转移风险的新型分子标志.     

应用基因芯片检测喉鳞状细胞癌甲醛固定石蜡包埋组织microRNA表达谱

目的 建立以甲醛固定石蜡包埋组织为材料、基于基因芯片技术的microRNA(miRNA)表达谱的分析方法 ;筛选与喉鳞状细胞癌(简称喉癌)生物学特征密切相关的差异表达miRNA.方法 从喉癌甲醛固定石蜡包埋组织中制备总RNA,经质量鉴定后进行荧光标记.采用Agilent公司的容纳723条人类miRNA探针的基因芯片完成杂交实验,以获得喉癌的miRNA表达谱.以GeneSpring GX和R-Project软件处理分析基因芯片实验数据,筛选与喉癌转移相关的差异表达miRNA.结果 从24例甲醛固定石蜡包埋组织标本中获得了符合基因芯片实验质量标准的RNA样品,并完成了基因芯片杂交及数据分析.从中共鉴定到319个miRNA,有96个miRNA在24例喉癌中均有表达,其中与淋巴结转移密切相关的(检错率<0.05)差异表达miRNA有5个,分别为miR-23a* 、miR-28-5p、miR-15a、miR-16和miR-425.结论 甲醛固定石蜡包埋组织可以提供符合基因芯片分析质量要求的miRNA,是研究miRNA的重要样品资源.从喉癌的miRNA表达谱中筛选出的转移相关差异表达miRNA(miR-23a*、miR-28-5p、miR-15a、miR-16和miR-425)有可能成为评估喉癌转移风险的新型分子标志.     

喉癌组织中的microRNA差异表达谱及miR-125a-5p抑制喉癌细胞增殖的初步研究

 目的：筛选并分析喉癌组织与周围正常喉黏膜的微小RNA(microRNAs,miRNAs) 之间的表达谱差异,为进一步研究miRNA与喉癌发生、发展的关系提供线索。方法：收集喉癌组织和癌旁正常喉黏膜标本共42对,随机选取10对标本进行miRNA微阵列基因芯片分析, 另选取32对标本进行实时荧光定量PCR （qRT-PCR）验证,获得喉癌组织中的miRNA差异表达谱。应用MTT法和克隆形成实验检测miR-125a-5p对喉癌Hep2细胞增殖的影响。结果：喉癌组织中的let-7f-5p、miR-10a-5p、miR-125a-5p、miR-144-3p、miR-195-5p、miR-203等6个miRNA在基因芯片以及qRT-PCR中表达均显著下调。与对照组相比,转染miR-125a-mimics组的喉癌Hep2细胞增殖能力受到抑制,而转染miR-125a-inhibitor组Hep2细胞增殖能力增强。结论：基因芯片与qRT-PCR结果一致;喉癌与正常喉黏膜之间存在明显的miRNA差异表达,这些miRNA的差异性表达可能与喉癌的发病、侵袭等相关。miR-125a可以抑制喉癌Hep2细胞的增殖,可能作为喉癌生物治疗的新靶点。     

Comprehensive microRNA profiling reveals a unique human embryonic stem cell signature dominated by a single seed sequence

Embryonic stem cells are unique among cultured cells in their ability to self-renew and differentiate into a wide diversity of cell types, suggesting that a specific molecular control network underlies these features. Human embryonic stem cells (hESCs) are known to have distinct mRNA expression, global DNA methylation, and chromatin profiles, but the involvement of high-level regulators, such as microRNAs (miRNA), in the hESC-specific molecular network is poorly understood. We report that global miRNA expression profiling of hESCs and a variety of stem cell and differentiated cell types using a novel microarray platform revealed a unique set of miRNAs differentially regulated in hESCs, including numerous miRNAs not previously linked to hESCs. These hESC-associated miRNAs were more likely to be located in large genomic clusters, and less likely to be located in introns of coding genes. hESCs had higher expression of oncogenic miRNAs and lower expression of tumor suppressor miRNAs than the other cell types. Many miRNAs upregulated in hESCs share a common consensus seed sequence, suggesting that there is cooperative regulation of a critical set of target miRNAs. We propose that miRNAs are coordinately controlled in hESCs, and are key regulators of pluripotence and differentiation. Disclosure of potential conflicts of interest is found at the end of this article.     

Quantitative nuclease protection assay in paraffin-embedded tissue replicates prognostic microarray gene expression in diffuse large-B-cell lymphoma

Gene expression profiling (GEP) has identified genes whose expression levels predict patient survival in diffuse large-B-cell lymphoma (DLBCL). Such discovery techniques generally require frozen samples unavailable for most patients. We developed a quantitative nuclease protection assay to measure expression levels of prognostic DLBCL genes using formalin-fixed, paraffin-embedded (FFPE) tissue. FFPE tissue was sectioned, permeabilized, denatured in the presence of specific probes, and hybridized to mRNA in situ. Nuclease subsequently destroyed non-hybridized probe. Alkaline hydrolysis freed mRNA-bound probes from tissue, which were transferred to ArrayPlates for probe capture and chemiluminescent quantification. We validated assay performance using frozen, fresh, and FFPE DLBCL samples, then used 39 archived DLBCL, previously microarray analyzed, to correlate GEP and ArrayPlate results. We compared old (>18 years) with new (<2 months) paraffin blocks made from previously frozen tissue from the original biopsy. ArrayPlate gene expression results were confirmed with immunohistochemistry for BCL2, BCL6, and HLA-DR, showing agreement between mRNA species and the proteins they encode. Assay performance was linear to approximately 1 mg sample/well. RNase and DNase treatments demonstrated assay specificity for RNA detection, both fixed and soluble RNA detection. Comparisons were excellent for lysate vs snap-frozen vs FFPE (R(2)>0.98 for all comparisons). Coefficients of variation for quadruplicates on FFPE were generally <20%. Correlation between new and old paraffin blocks from the same biopsy was good (R(2)=0.71). Comparison of ArrayPlate to Affymetrix and cDNA microarrays showed reasonable correlations. Insufficient power from small sample size prevented successfully correlating results with patient survival, although hazard ratios trended the expected directions. We developed an assay to quantify expression levels of survival prediction genes in DLBCL using FFPE, fresh, or frozen tissue. While this technique cannot replace GEP for discovery, it indicates that expression differences identified by GEP can be replicated on a platform applicable to archived FFPE samples.