RESUMO
BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNA molecules. Reduced or increased levels of specific miRNAs are observed in colon and other cancers, supporting their role in carcinogenesis. Detection of colorectal polyps is the cornerstone of the Bowel Cancer Screening Programme in the UK. However, uptake of screening nationally remains under 60%. We aimed to see whether circulating plasma miRNAs can be used to screen for patients with colorectal polyps, adenomas, or both. METHODS: Blood samples were taken from patients from the Bowel Cancer Screening Programme (asymptomatic but faecal occult blood testing [FOBt] positive). Plasma RNA was extracted, target miRNAs (19a, 98, 146b, 186, 191, 222*, 331-5p, 452, 625, 664, 1247) were identified on pooled case miRNA assay cards, and miRNA fraction was quantified by quantitative RT-PCR assay. Results were compared with endoscopy reports and with histology of any polyps identified and removed. Analysis was done with Excel (2011) and SPSS (version 20) software. FINDINGS: 210 patients were included (117 with polyps, 12 with cancer, 81 healthy controls [FOBt positive]). The miRNA panel showed significant differences in expression (on t testing) for patients compared with controls for those with polyps, cancer, or both (miR-19a, p=0·0184; miR-98, p=0·0206; miR-146b, p=0·0029; miR-186, p=0·0006; miR-62,5 p=0·0008), polyps (miR-19a, p=0·0233; miR-98, p=0·0224; miR-146b, p=0·003; miR-186, p=0·0004; miR-625, p=0·001), adenomas (miR-19a, p=0·0339; miR-98, p=0·0266; miR-146b, p=0·0045; miR-186, p=0·0008; miR-625, p=0·0049), multiple adenomas (both sides of colon; miR-146b, p=0·0194; miR-186, p=0·0226; miR-625, p=0·0013), and right-sided adenomas (miR-98, p=0·031; miR-146b, p=0·0076; miR-186, p=0·0041; miR-331-5p, p=0·0142; miR-625, p=0·0049). Receiver operating characteristic analysis showed sensitivity of 60% or more, and specificity of 86% or more for men with polyps, men with adenomas, all patients with haemorrhoids or diverticulosis and polyps, and all patients with haemorrhoids or diverticulosis and adenomas. INTERPRETATION: The target miRNAs that we identified showed significant differences in expression levels for patients with polyps and patients with adenomas from controls. Use of this panel has potential as a screening test. FUNDING: Bowel Disease Research Foundation.
RESUMO
BACKGROUND: Ulcerative colitis is an established risk factor for colorectal cancer, also known as colitis-associated cancer. Existing colonoscopic-based surveillance has many disadvantages, so a new accurate, efficient, cost-effective screening test is needed. MicroRNAs (miRNAs) regulate gene expression and are dysregulated in a range of diseases, including ulcerative colitis and colorectal cancer. This study aimed to establish the miRNAs associated with colitis-associated cancer. METHODS: Blood samples were collected from 45 adult patients undergoing colonoscopic screening for ulcerative colitis at the Leicester General Hospital, Leicester, UK. Pool A and B TaqMan Array 384-well cards were used to quantify the expression of 754 miRNAs in the circulating plasma. 28 high priority miRNA candidates showing abnormal expression were validated with real-time quantitative PCR. FINDINGS: Patients were allocated to three disease groups (ulcerative colitis, n=37; dysplasia, n=2; colitis-associated cancer, n=6). Analysis of variance was used to assess differences between the groups. miR-375 was significantly upregulated in the colitis-associated cancer cohort (p=0·0061) compared with active ulcerative colitis. Combining several miRNAs in a panel increased the capacity of the test to distinguish between colitis-associated cancer and different ulcerative colitis activity states. INTERPRETATION: Our study suggests that miRNAs have the potential to act as blood-based biomarkers to monitor the activity and progression of disease in patients with ulcerative colitis. FUNDING: Royal College of Surgeons of England.
RESUMO
The development of Colorectal Cancer (CRC) follows a sequential progression from adenoma to the carcinoma. Therefore, opportunities exist to interfere with the natural course of disease development and progression. Dysregulation of microRNAs (miRNAs) in cancer cells indirectly results in higher levels of messenger RNA (mRNA) specific to tumour promoter genes or tumour suppressor genes. This narrative review aims to provide a comprehensive review of the literature about the manipulation of oncogenic or tumour suppressor miRNAs in colorectal cancer cells for the purpose of development of anticancer therapies. A literature search identified studies describing manipulation of miRNAs in colorectal cancer cells in vivo and in vitro. Studies were also included to provide an update on the role of miRNAs in CRC development, progression and diagnosis. Strategy based on restoration of silenced miRNAs or inhibition of over expressed miRNAs has opened a new area of research in cancer therapy. In this review article different techniques for miRNA manipulation are reviewed and their utility for colorectal cancer therapy has been discussed in detail. Restoration of normal equilibrium for cancer related miRNAs can result in inhibition of tumour growth, apoptosis, blocking of invasion, angiogenesis and metastasis. Furthermore, drug resistant cancer cells can be turned into drug sensitive cells on alteration of specific miRNAs in cancer cells. MiRNA modulation in cancer cells holds great potential to replace current anticancer therapies. However, further work is needed on tissue specific delivery systems and strategies to avoid side effects.
