MicroRNA profiling of diagnostic needle aspirates from patients with pancreatic cancer

Abstract

Background:A major challenge to the development of biomarkers for pancreatic cancer (PC) is the small amount of tissue obtained at the time of diagnosis. Single-gene analyses may not reliably predict biology of PC because of its complex molecular makeup. MicroRNA (miRNA) profiling may provide a more informative molecular interrogation of tumours. The primary objective of this study was to determine the feasibility of performing miRNA arrays and quantitative real-time PCR (qRT–PCR) from archival formalin-fixed paraffin-embedded (FFPE) cell blocks obtained from fine-needle aspirates (FNAs) that is the commonest diagnostic procedure for suspected PC.Methods:MicroRNA expression profiling was performed on FFPE from FNA of suspicious pancreatic masses. Subjects included those who had a pathological diagnosis of pancreatic adenocarcinoma and others with a non-malignant pancreatic histology. Exiqon assay was used to quantify miRNA levels and qRT–PCR was used to validate abnormal expression of selected miRNAs.Results:A total of 29 and 15 subjects had pancreatic adenocarcinoma and no evidence of cancer, respectively. The RNA yields per patient varied from 25 to 100 ng. Profiling demonstrated deregulation of over 228 miRNAs in pancreatic adenocarcinoma of which the top 7 were further validated by qRT–PCR. The expression of let-7c, let-7 f, and miR-200c were significantly reduced in most patients whereas the expression of miR-486-5p and miR-451 were significantly elevated in all pancreas cancer patients. MicroRNAs let-7d and miR-423-5p was either downregulated or upregulated with a significant inter-individual variation in their expression.Conclusion:This study demonstrated the feasibility of using archival FFPE cell blocks from FNAs to establish RNA-based molecular signatures unique to pancreatic adenocarcinoma with potential applications in clinical trials for risk stratification, patient selection, and target validation.

Towards a clinical use of miRNAs in pancreatic cancer biopsies

“…The two significantly upregulated miRNAs (miR-486-5p and miR-451) have not been well described in PDAC and deserve further investigation as possible oncogenic miRNAs. Regarding the validation of deregulated miRNAs, Ali et al should have considered validating miR-92a, as it was found to be significantly upregulated (log2-fold change +3.41) in PDAC on their microarray [1]. This miRNA is a member of the highly oncogenic polycistronic miR-17-92 cluster (aka oncomiR-1) [3] and has been shown to be upregulated in hepatocellular carcinoma [4] and a potential plasma and fecal biomarker for colorectal cancer [5].…”

“…Furthermore, the study by Ali et al [1] is not the first to look at miRNAs in FFPE biopsies from PDAC patients. Although they used a different quantification technique, Preis et al [12] demonstrated that fluorescencebased in situ hybridization using locked nucleic acid-modified DNA probes against oncomiR-21 and miR-10b on FFPE sections of EUS-FNA samples could differentiate PDAC from normal pancreas (PDAC: n = 95; benign: n = 11).…”

“…A recent meta-analysis has shown that pooled sensitivity for malignant cytology was 85% and specificity was 98%, and if suspicious cytological results were included to determine true neoplasms, the sensitivity increased to 91%, but specificity dropped to 94% [7], whereas percutaneous CT-guided FNA of pancreatic lesions is normally used to simply confirm the diagnosis of malignancy before commencing palliative treatment [8]. The aim of the current study [1] was to "establish the feasibility of miRNA expression profiling of localised PDAC using material obtained from diagnostic FNA." To this end, the study was successful.…”

“…Fine-needle aspirations (FNAs) from patients with suspicious pancreatic lesions were collected from computed tomography (CT) or endoscopic ultrasound (EUS)-guided biopsies for cytological and miRNA analysis [1]. An average of three needle passes (range: 2-5 passes) were taken from each tumor.…”

MicroRNA-486-5p enhances hepatocellular carcinoma tumor suppression through repression of IGF-1R and its downstream mTOR, STAT3 and c-Myc

“…It is important to note that miR-486-5p has also been found to be downregulated in numerous other cancer types, including pancreatic cancer (34), gastric cancer (29), osteosarcoma (35), and lung cancer (23), however, the mechanism of miR-486-5p downregulation in those types of cancer, including HCC, is largely unknown. According to previous studies, miR-486-5p downregulation in HCC tissues could be highly accredited to its chromosomal location (8p11.21), which is one of the most typically occurring genomic deletion regions, containing potential tumor suppressor genes (29).…”