Circular RNA (circRNA) is a novel class of single-stranded RNAs with a closed loop structure. The majority of circRNAs are formed by a back-splicing process in pre-mRNA splicing. Their expression is dynamically regulated and shows spatiotemporal patterns among cell types, tissues and developmental stages. CircRNAs have important biological functions in many physiological processes, and their aberrant expression is implicated in many human diseases. Due to their high stability, circRNAs are becoming promising biomarkers in many human diseases, such as cardiovascular diseases, autoimmune diseases and human cancers. In this review, we focus on the translational potential of using human blood circRNAs as liquid biopsy biomarkers for human diseases. We highlight their abundant expression, essential biological functions and significant correlations to human diseases in various components of peripheral blood, including whole blood, blood cells and extracellular vesicles. In addition, we summarize the current knowledge of blood circRNA biomarkers for disease diagnosis or prognosis.
Autoimmune Diseases/blood* ; Biomarkers, Tumor/blood* ; Cardiovascular Diseases/blood* ; Humans ; Liquid Biopsy ; Neoplasms/blood* ; RNA, Circular/blood* ; RNA, Neoplasm/blood*

OBJECTIVETo investigate the relationship between the expression of murine double minute 2 (MDM2) oncogene and non-Hodgkin lymphoma (NHL) in childhood.

METHODSThirty-one cases of NHL were enrolled in this study as patient group and 8 cases of lymphadenitis as control group. (1) Immunohistochemistry ultrasensitive S-P assay was used to detect the expression of MDM2 protein in pathological tissues in all cases. Positive cells were dyed yellow or brown in nuclei. MDM2 positive cell was defined as >/= 10% of the tumor cells were positive, which was overexpression of MDM2 protein. (2) RT-PCR (reverse transcription-polymerase chain reaction) was performed to value the overexpression of MDM2 mRNA in the pathological tissues and mononuclear cells in peripheral blood. While the ratio of MDM2/beta-actin was >16% was defined as overexpression of MDM2 mRNA.

RESULTS(1) Rates of overexpression of MDM2 protein and MDM2 mRNA were 64.5% and 61.3%, respectively, which were significantly different as compared to that of control group (P < 0.05 and P < 0.01, respectively). (2) The relationship analysis among subgroups in the experiment group showed that the overexpression of MDM2 protein did not correlate with classifications of working formulation, cellular origin, sex, clinical stage and involved extranodal sites (P > 0.05), but significantly correlated with classifications of B status and the increased serum LDH level (P < 0.05). It was shown that the overexpression of MDM2 mRNA did not correlate with classifications of working formulation, cellular origin, sex and clinical stage (P > 0.05), significantly correlated with B status (P < 0.05), and was remarkably significantly correlated with the involved extranodal sites and the increased serum LDH level (P < 0.01). (3) It was demonstrated that the overexpression of MDM2 mRNA in the pathological tissues was similar to the overexpression of MDM2 protein in the pathological tissues and MDM2 mRNA in peripheral blood (P > 0.05, kappa = 0.655 and 0.571), and the overexpression of MDM2 protein in the pathological tissues was similar to that of MDM2 mRNA in peripheral blood (P > 0.05, kappa = 0.609).

CONCLUSIONS(1) The rate of MDM2 oncogene overexpression was quite high. (2) The overexpression of MDM2 protein in pathological tissues determined by using immunohistochemistry ultrasensitive S-P assay was similar to that of MDM2 mRNA in pathological tissues detected by using RT-PCR method. Both methods might be used to detect the overexpression of MDM2 oncogene in the cases of childhood NHL. (3) The overexpression of MDM2 oncogene related to the poor status and poor prognosis of patients with childhood NHL.

Biomarkers, Tumor ; analysis ; blood ; Child ; Humans ; Immunohistochemistry ; Lymphoma, Non-Hodgkin ; blood ; genetics ; metabolism ; Neoplasm Proteins ; blood ; genetics ; Oncogenes ; Proto-Oncogene Proteins c-mdm2 ; blood ; genetics ; metabolism ; RNA, Messenger

OBJECTIVETo evaluate the clinical significance of CK20 mRNA expression in detecting disseminated tumor cells in peripheral blood of gastric and colorectal cancer patients.

METHODSExpression of CK20 mRNA was investigated by RT-PCR in bone marrow, portal vein and peripheral blood in 47 gastric, 58 colorectal cancer patients and 6 non-cancer volunteers. All the patients were followed-up for one year.

RESULTSThere was no positive expression of CK20 mRNA in 6 non-cancer volunteers. The positive rates of CK20 mRNA in bone marrow, portal vein were 87.2% (41/47) and 85.1% (40/47) in gastric cancer, and were 77.6% (45/58) and 74.1% (43/58) in colorectal cancer. The positive rates of CK20 mRNA in peripheral blood in gastric and colorectal cancer patients were 42.6% (20/47) and 44.8% (26/58) by one single test, and were 74.5% (35/47) and 69.0% (40/58) by two tests. The overall positive rate of CK20 mRNA in peripheral blood (two tests) was similar to that in bone marrow and portal vein. The overall positive rate of CK20 mRNA in peripheral blood was higher in two tests than in one single test (P < 0.05) and in advanced than early lesions. The relapse rate within one year was higher in CK20 mRNA positive patients than the negative ones (P < 0.05).

CONCLUSIONDetection of cancer cells by RT-PCR for CK20 mRNA in peripheral blood, being as sensitive and specific as in bone marrow and portal vein, is reliable and convenient in diagnosing micrometastasis of gastric and colorectal cancer, which possesses clinical significance in assessing the prognosis and scheme of therapy.

Adolescent ; Adult ; Aged ; Biomarkers, Tumor ; blood ; Colorectal Neoplasms ; blood ; pathology ; Female ; Humans ; Intermediate Filament Proteins ; blood ; genetics ; Keratin-20 ; Male ; Middle Aged ; Neoplasm Metastasis ; Neoplastic Cells, Circulating ; chemistry ; RNA, Neoplasm ; blood ; Reverse Transcriptase Polymerase Chain Reaction ; Stomach Neoplasms ; blood ; pathology

OBJECTIVETo develop a sensitive and specific RT-PCR assay using the mRNA of MAGE-1 and MAGE-3 genes as specific tumor markers for the detection of the tumor cells in the peripheral blood of patients with gastric cancer.

METHODSPeripheral blood was obtained from 40 patients with gastric cancer and from 20 healthy volunteers. The mRNA of MAGE-1 and MAGE-3 genes in the peripheral blood mononuclear cells (PBMC) was detected by RT-PCR. The expressions of MAGE-1 and MAGE-3 mRNA in the tumor tissues of these gastric cancer patients were also detected by RT-PCR. Meanwhile,CEA expression by nested RT-PCR in PBMC of 40 gastric cancer patients was also detected.

RESULTSOf 40 gastric cancer patients, MAGE-1 and MAGE-3 mRNA were positive in 47.5% (19/40) and 25% (10/40) of PBMC respectively, and in 62.5% (25/40) and 30% (12/40) of gastric cancer tissues respectively. As a whole, in the PBMC of 40 gastric cancer patients, 25 (62.5%) samples were found to express at least one type of MAGE mRNA. In the patients whose tumors did not express MAGE-1 and/or MAGE-3 genes, the corresponding MAGE mRNA was also undetected in their PBMC. There was no expression of MAGE-1 or MAGE-3 gene in the PBMC from the 20 healthy donors. The positive rate of MAGE mRNA in PBMC was closely correlated with the tumor stage and lymph node metastasis (P <0.05). Positive rate of CEA gene expression was 32.5% (13/40) in the PBMC of 40 gastric cancer patients, 29 (72.5%)samples were detected to express at least one type of MAGE gene and CEA gene mRNA.

CONCLUSIONSMAGE-1, MAGE-3 and CEA mRNA are specifically detected with high percentage in the PBMC of gastric cancer patients by RT-PCR. They could be used as specific tumor markers for the detection of the circulating gastric cancer cells, and the detection results may be helpful to evaluate the prognosis of gastric cancer patients.

Adult ; Aged ; Antigens, Neoplasm ; blood ; genetics ; Biomarkers, Tumor ; blood ; Carcinoembryonic Antigen ; blood ; Female ; Humans ; Male ; Melanoma-Specific Antigens ; Middle Aged ; Neoplasm Proteins ; blood ; genetics ; RNA, Messenger ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Sensitivity and Specificity ; Stomach Neoplasms ; blood ; genetics ; pathology

OBJECTIVE: To explore clinical evaluate of CK19 mRNA and EGFR mRNA for diagnosis of laryngeal carcinoma micrometastasis, correlation between circulation tumor cell and lymph node metastasis. METHOD: Of 30 nude mice, 25 were randomly divided into 5 experimental groups (5 mice in each group), 5 were acted as control group. The mice were killed 2,4,6,8 and 10 weeks after injection. The expression of CK19 and EGFR mRNA in the peripheral blood and tumor tissue were detected by RT-PCR assay. The expression of EGFR in tumor tissue were detected by immunohistochemistry and lymph node transfer were confirmed using continuous pathological dying. RESULT: None of CK19 and EGFR mRNA were detected in peripheral blood of control group, CK19 mRNA-positive rate was 48% and 80% in peripheral blood and tumor tissue from the experimental group, respectively, and EGFR mRNA-positive rate was 36% and 76%, respectively. Lymph node metastasis happened in the exponential growth phase and transfer rate was 60%(15/25). The expression of CK19 mRNA and EGFR mRNA in lymphatic metastasis groups was higher than that of control, with a positive correlation between lymphatic metastasis and CTC (r = 0.655 , P < 0.01). The protein positive expression rate of EGFR were 88%(22/25) in tumor tissue. All peripheral blood expressed EGFR concomitant EGFR expressing in tumor tissues, and a high expression of EGFR in tumor tissue displayed high expression of EGFR in peripheral blood as well. CONCLUSION The expression of CK19 and EGFR mRNA in the peripheral blood can provide predictive information of lymphatic metastasis, EGFR mRNA might be a new target of treatment and diagnosis for malignant tumour.
Animals ; Disease Models, Animal ; ErbB Receptors ; blood ; Keratin-19 ; blood ; Laryngeal Neoplasms ; blood ; pathology ; Lymphatic Metastasis ; Mice ; Mice, Nude ; Neoplasm Staging ; RNA, Messenger ; genetics

Adult ; Aged ; Breast Neoplasms ; blood ; pathology ; Carcinoembryonic Antigen ; blood ; genetics ; Carcinoma, Ductal, Breast ; blood ; secondary ; Female ; Fibroadenoma ; blood ; Fibrocystic Breast Disease ; blood ; Humans ; Lymphatic Metastasis ; Middle Aged ; Neoplasm Staging ; RNA, Messenger ; blood ; genetics

OBJECTIVETo explore the relationship between hypoxia-inducible factor-1α (HIF-1α) mRNA levels in the peripheral blood and the metastasis of colorectal cancer.

METHODSHIF-1α mRNA in the peripheral blood was detected by RT-PCR in 40 patients with colorectal cancer and 20 healthy subjects.

RESULTSSeventeen patients with colorectal cancer showed positivity for HIF-1α mRNA, showing a significantly higher positivity rate (42.5%) than the healthy subjects (P<0.05). The expression of HIF-1α mRNA is closely related to the staging of colorectal cancer (CRC).

CONCLUSIONHIF-1α mRNA may serve as a potential marker in the detection of metastasis of colorectal cancer.

Adenocarcinoma ; blood ; pathology ; Adult ; Aged ; Aged, 80 and over ; Case-Control Studies ; Colorectal Neoplasms ; blood ; pathology ; Female ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; blood ; genetics ; Male ; Middle Aged ; Neoplasm Invasiveness ; Neoplasm Metastasis ; RNA, Messenger ; genetics

DNA, Complementary ; chemistry ; Humans ; Leukocytes ; enzymology ; Lung Neoplasms ; enzymology ; pathology ; Matrix Metalloproteinase 2 ; blood ; genetics ; Matrix Metalloproteinase 9 ; blood ; genetics ; Neoplasm Invasiveness ; Neoplasm Metastasis ; RNA, Messenger ; analysis ; Tissue Inhibitor of Metalloproteinase-1 ; blood ; genetics

OBJECTIVETo study the relationship between peripheral blood hepatocellular carcinoma cells-associated AFP mRNA and tumor relapse and metastasis.

METHODSTo detect several blood samples from the HCC patients by nested RT-PCR to find out AFP mRNA after 24 h, 72 h and one week and 4 weeks after surgery, and followed up the HCC patients for 1, 2, 3 years.

RESULTSThere were 7 patients occurred relapse or distant metastasis in 12 patients with AFP mRNA positive (7/12, 58.3%), there were 5 patients occurred relapse in 19 patients with AFP mRNA negative (5/19, 26.3%) within 1 year, there was 4 patients occurred relapse in second year (9/19, 47.3%); 5 patients occurred relapse in third year (10/19, 52.6%). Obvious connection between patients AFP mRNA positive and AFP mRNA negative was observed (P < 0.01).

CONCLUSIONSHCC with AFP mRNA positive has more change to be recurrent compared with HCC patients with AFP mRNA negative.

Adult ; Carcinoma, Hepatocellular ; blood ; pathology ; surgery ; Female ; Follow-Up Studies ; Humans ; Liver Neoplasms ; blood ; pathology ; surgery ; Male ; Middle Aged ; Neoplasm Metastasis ; Neoplasm Recurrence, Local ; Neoplastic Cells, Circulating ; Postoperative Period ; RNA, Messenger ; blood ; alpha-Fetoproteins ; genetics ; metabolism

OBJECTIVETo study the expression of human mammaglobin (hMAM) mRNA in the peripheral blood of breast cancer patients and its implication.

METHODSThe expression of human mammaglobin mRNA was determined by using RT-PCR method in 56 patients with peripheral blood breast cancer, 8 patients with breast hyperplasia and 8 women with normal breast. The expression of hMAM mRNA was compared with biological significance and change of hMAM mRNA in chemotherapy after operation.

RESULTSThe expression of hMAM mRNA was negative in 8 patients with breast hyperplasia, 8 women with normal breast and 56 patients with breast cancer, The positive rate was 30.4% (17/56) (chi(2) = 19.766, P < 0.01). The expression of hMAM mRNA in peripheral blood was not correlated with clinical stage, primary tumor size and patients age (chi(2) = 1.256, P > 0.05). After short-term large dose of chemotherapy, 41.2% (7/17) patients turned positive before operation to negative hMAM mRNA expression and negetive expression before operation positive expression after chemotherapy.

CONCLUSIONSThis study suggests that hMAM is sensitive and specific for breast cancer. Detection of the expression of hMAM mRNA in peripheral blood of breast cancer is of value in the diagnosis and judgement of prognosis of breast cancer.

Adult ; Aged ; Aged, 80 and over ; Biomarkers, Tumor ; blood ; Breast Neoplasms ; blood ; diagnosis ; Female ; Gene Expression ; Humans ; Leukocytes, Mononuclear ; metabolism ; Mammaglobin A ; Middle Aged ; Neoplasm Proteins ; blood ; genetics ; Prognosis ; RNA, Messenger ; blood ; Uteroglobin ; blood ; genetics