BackgroundWhile DNA barcoding is an important technology for the authentication of the botanical origins of Chinese medicines, the suitable markers for DNA barcoding of the genus Uncaria have not been reported yet. This study aims to determine suitable markers for DNA barcoding of the genus Uncaria (Gouteng).MethodsGenomic DNA was extracted from the freshly dried leaves of Uncaria plants by a Bioteke’s Plant Genomic DNA Extraction Kit. Five candidate DNA barcode sites (ITS2, rbcL, psbA–trnH, ITS, and matK) were amplified by PCR with established primers. The purified PCR products were bidirectionally sequenced with appropriate amplification primers in an ABI-PRISM3730 instrument. The candidate DNA barcodes of 257 accessions of Uncaria in GenBank were aligned by ClustalW. Sequence assembly and consensus sequence generation were performed with CodonCode Aligner 3.7.1. The identification efficiency of the candidate DNA barcodes was evaluated with BLAST and nearest distance methods. The interspecific divergence and intraspecific variation were assessed by the Kimura 2-Parameter model. Genetic distances were computed with Molecular Evolutionary Genetics Analysis 6.0.ResultsThe accessions of the five candidate DNA barcodes from 11 of 12 species of Uncaria in China and four species from other countries were included in the analysis, while 54 of total accessions were submitted to GenBank. In a comparison of the interspecific genetic distances of the five candidate barcodes, psbA–trnH exhibited the highest interspecific divergence based on interspecific distance, theta prime, and minimum interspecific distance, followed by ITS2. The distribution of the interspecific distance of ITS2 and psbA–trnH was higher than the corresponding intraspecific distance. Additionally, psbA–trnH showed 95.9 % identification efficiency by both the BLAST and nearest distance methods regardless of species or genus level. ITS2 exhibited 92.2 % identification efficiency by the nearest distance method, but 87 % by the BLAST method.ConclusionWhile psbA–trnH and ITS2 (used alone) were applicable barcodes for species authentication of Uncaria, psbA–trnH was a more suitable barcode for authentication of Uncaria macrophylla.Electronic supplementary materialThe online version of this article (doi:10.1186/s13020-015-0072-7) contains supplementary material, which is available to authorized users.

Background. The association of miR-28-5p with colon cancer remains to be elucidated. This study aimed to determine the clinical significance and prognostic value of miR-28-5p in colon cancer. Methods. We retrospectively analyzed the data of miR-28-5p in colon adenocarcinoma data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), and the data was divided into cancer group and normal group, respectively. Forty colon cancer tissues and adjacent normal tissues were collected and tested by qRT-PCR methods. The difference of the miR-28-5p expression between colon cancer and normal tissues was compared. The clinical significance of miR-28-5p in colon cancer and the association with the survival were determined. The predictive value of miR-28-5p in clinical features was determined using receiver operating characteristic curve. The target genes of miR-28-5p were identified, and the functional of target genes was performed using bioinformatics analysis. Results: The expression of miR-28-5p was increased in colon cancer tissues compared with normal controls (p=0.037). The expression of miR-28-5p was significantly increased in tissues with distant metastases compared with that without distant metastases (p=0.026). Patients with high expression of miR-28-5p have a shorter survival time than those with low expression (p=0.004). Cox analysis showed that miR-28-5p was an independent predictor for the survival of patients (p=0.014). Combination of miR-28-5p with TNM stage and clinical stage can improve the prognostic value for the patients (p<0.05). miR-28-5p has a moderate predictive value in predicting the TNM stage and clinical stage (T stage: AUC=0.515; N stage: AUC=0.523, M stage: AUC=0.572; clinical stage: AUC=0.539). 711 potential target genes of miR-28-5p were screened; their function and pathways were identified. Conclusions: This study demonstrated that miR-28-5p was increased in colon cancer and can be an independent indicator for the overall survival in patients with colon cancer.

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