Abstract
BackgroundBreast cancer circulating biomarkers include carcinoembryonic antigen and carbohydrate antigen 15–3, which are used for patient follow-up. Since sensitivity and specificity are low, novel and more useful biomarkers are needed. The presence of stable circulating microRNAs (miRNAs) in serum or plasma suggested a promising role for these tiny RNAs as cancer biomarkers. To acquire an absolute concentration of circulating miRNAs and reduce the impact of preanalytical and analytical variables, we used the droplet digital PCR (ddPCR) technique.ResultsWe investigated a panel of five miRNAs in the sera of two independent cohorts of breast cancer patients and disease-free controls. The study showed that miR-148b-3p and miR-652-3p levels were significantly lower in the serum of breast cancer patients than that in controls in both cohorts. For these two miRNAs, the stratification of breast cancer patients versus controls was confirmed by receiver operating characteristic curve analyses. In addition, we showed that higher levels of serum miR-10b-5p were associated with clinicobiological markers of poor prognosis.ConclusionsThe study revealed the usefulness of the ddPCR approach for the quantification of circulating miRNAs. The use of the ddPCR quantitative approach revealed very good agreement between two independent cohorts in terms of comparable absolute miRNA concentrations and consistent trends of dysregulation in breast cancer patients versus controls. Overall, this study supports the use of the quantitative ddPCR approach for monitoring the absolute levels of diagnostic and prognostic tumor-specific circulating miRNAs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40364-015-0037-0) contains supplementary material, which is available to authorized users.
Highlights
Breast cancer is the most frequent cancer and the second leading cause of cancer death among women in industrialized countries
Using droplet digital PCR (ddPCR), we investigated five miRNAs in the sera of two independent cohorts of breast cancer patients and disease-free controls to verify whether miRNAs could represent useful diagnostic biomarkers of breast cancer
We did not find significant differences in cohort A. Since this group consisted of patients carrying stage I or II cancers, this finding does not contradict a positive correlation between miR-10b and more advanced disease; it is consistent with the results described in a report by Roth et al, who found a higher level of miR-10b in patients with metastatic disease [10]
Summary
Breast cancer is the most frequent cancer and the second leading cause of cancer death among women in industrialized countries. Mangolini et al Biomarker Research (2015) 3:12 transcriptional level [5] They play a crucial role in the regulation of most, if not all, human genes and their involvement in the deregulation of pathological states such as cancer has been well established [6]. MiRNAs can be detected in serum or plasma, and their levels may be altered in pathological conditions. Because of their remarkable stability in plasma and serum and the possibility of measuring their levels using noninvasive methods, various studies have suggested a role for circulating miRNAs as novel cancer biomarkers [7,8,9,10,11]. To acquire an absolute concentration of circulating miRNAs and reduce the impact of preanalytical and analytical variables, we used the droplet digital PCR (ddPCR) technique
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