Other studies provide further support for the use of circulating Compound C miRNAs as non-invasive biomarkers for a wide range of cancers, including hepatocellular carcinoma [80, 81], malignant melanoma Small molecule library order [82] and gastric cancer [83] (Table 1). Moreover, researchers found that circulating miRNAs might be used to detect early stage cancer. Zheng et al. reported that the levels of miR-155, miR-197 and miR-182 in the plasma of lung cancer patients, including stage I cancers, were significantly elevated compared with controls. The combination of these three miRNAs yielded 81.33% sensitivity and 86.76% specificity in discriminating

lung cancer patients from controls [84]. Schrauder and colleagues performed microarray-based miRNA profiling on whole blood from 48 breast cancer patients at diagnosis along with 57 healthy individuals as controls. All breast cancers were histologically confirmed as early stage invasive ductal carcinoma of the breast with a tumor size ranging between 0.15 and 4.0 cm. They found that 59 miRNAs were significantly differentially expressed in whole blood from cancer patients compared with healthy controls, and that 13 and 46 miRNAs were significantly up- or down-regulated, respectively [85]. Bianchi

et al. developed a test, based on the detection of 34 miRNAs from serum, that could identify early stage NSCLC in a population of asymptomatic high-risk individuals with 80% accuracy [86]. Table 1 Circulating LY2606368 clinical trial miRNAs as diagnostic markers for different human cancers Disease miRNA Expression level Contributors Breast cancer miR-29a Up-regulation Wu et al., J Biomed Biotechnol. (2010) [76]   miR-21   Asaga et al., Clin Chem. (2011) [77] Lung cancer miR-21,1254,574-5p Up-regulation Wei et al., Chin J Cancer. (2011) [79]       Foss et al., J Thorac Oncol. (2011) [78] Hepatocellular carcinoma miR-16,miR-199a Down-regulation Qu et al., J Clin Gastroenterol. (2011) [80]   miR-21,miR-122,miR-223 Up-regulation Xu et al., Mol Carcinog. (2010) [81] Malignant melanoma Protirelin miR-221 Up-regulation Kanemaru et al., J Dermatol Sci. (2011) [82] Gastric cancer miR-1,20a,27a,34,423-5p Up-regulation Liu et al., Eur J Cancer.

(2011) [83] In addition, some miRNAs may be useful prognostic biomarkers for different cancers. Hu et al. [87] used Solexa sequencing followed by qRT-PCR to test the difference in serum levels of miRNAs between NSCLC patients with longer and shorter survival. Eleven serum miRNAs were found to be altered more than five-fold between the two groups. Levels of four miRNAs (miR-486, miR-30d, miR-1 and miR-499) were significantly associated with overall survival, and this four-miRNA signature may serve as a predictor for overall survival in NSCLC patients. Cheng et al. [88] found that plasma miR-141 was an independent prognostic factor for advanced colon cancer and that high plasma levels of miR-141 were associated with poor prognosis.