Cell-free DNA from bile outperformed plasma as a potential alternative to tissue biopsy in biliary tract cancer

BACKGROUND

Biliary tract cancers (BTCs) are rare and highly heterogenous malignant neoplasms. Because obtaining BTC tissues is challenging, the purpose of this study was to explore the potential roles of bile as a liquid biopsy medium in patients with BTC.

PATIENTS AND METHODS

Sixty-nine consecutive patients with suspected BTC were prospectively enrolled in this study. Capture-based targeted sequencing was performed on tumor tissues, whole blood cells, plasma, and bile samples using a large panel consisting of 520 cancer-related genes.

RESULTS

Of the 28 patients enrolled in this cohort, tumor tissues were available in eight patients, and plasma and bile were available in 28 patients. Somatic mutations were detected in 100% (8/8), 71.4% (20/28), and 53.6% (15/28) of samples comprising tumor tissue DNA, bile cell-free DNA (cfDNA), and plasma cfDNA, respectively. Bile cfDNA showed a significantly higher maximum allele frequency than plasma cfDNA (P = 0.0032). There were 56.2% of somatic single-nucleotide variant (SNVs)/insertions and deletions (indels) shared between bile and plasma cfDNA. When considering the genetic profiles of tumor tissues as the gold standard, the by-variant sensitivity and positive predictive value for SNVs/indels in bile cfDNA positive for somatic mutations were both 95.5%. The overall concordance for SNVs/indels in bile was significantly higher than that in plasma (99.1% versus 78.3%, P < 0.0001). Moreover, the sensitivity of CA 19-9 combined with bile cfDNA achieved 96.4% in BTC diagnosis.

CONCLUSION

We demonstrated that bile cfDNA was superior to plasma cfDNA in the detection of tumor-related genomic alterations. Bile cfDNA as a minimally invasive liquid biopsy medium might be a supplemental approach to confirm BTC diagnosis.

MiR-129-2 weakens proliferation and promotes apoptosis of liver cancer cells by suppressing the Wnt signaling pathway

OBJECTIVE

To explore the effects of micro ribonucleic acid-129-2 (miR-129-2) on proliferation and migration of liver cancer cells and its possible mechanism.

PATIENTS AND METHODS

The expression level of miR-129-2 was measured in liver cancer tissues and adjacent tissues from patients with liver cancer. Its level in liver cancer HepG2 cells and normal liver cells L-02 was also detected via quantitative polymerase chain reaction (qPCR). MiR-192-2 overexpression model was established in the HepG2 cell line. The proliferation and apoptosis levels of cells were determined by methyl thiazolyl tetrazolium (MTT) assay and flow cytometry, respectively. Wound healing assay was performed to detect the migration ability of cells. The expressions level of genes in the Wnt signaling pathway were measured through Western blotting. Xenograft tumor model was conducted in nude mice for exploring the in vivo effects of miR-129-2 on liver cancer growth.

RESULTS

The expression level of miR-129-2 was significantly lower in liver cancer tissues than that in adjacent tissues (p<0.01), and it was overtly lower in HepG2 cells than that in L-02 cells (p<0.01). Overexpression of miR-129-2 weakened proliferation and migration abilities of liver cancer cells (p<0.01), and evidently increased apoptosis level (p<0.01). Sex-determining region Y-related HMG-box 4 (Sox4) and matrix metalloproteinase-2 (MMP-2) were downregulated, while phosphorylated glycogen synthase kinase-3β (p-GSK3β) was upregulated in liver cancer cells overexpressing miR-129-2. Besides, the weight and volume of tumors in nude mice bearing liver cancer were significantly smaller after overexpression of miR-129-2.

CONCLUSIONS

MiR-129-2 weakens proliferation and migration and stimulates apoptosis in liver cancer cells mainly by downregulating Sox4 and inactivating the Wnt signaling pathway.

Development of a rinsing separation method for exosome isolation and comparison to conventional methods

OBJECTIVE

Exosomes contain valuable biomarkers for many diseases. Tragically, standardized isolation methods and subsequent characterization criteria for exosomes remain limited. Therefore, we developed a new exosome isolation method, termed rinsing separation, and compared its advantages and weaknesses relative to the existing ultracentrifugation and ExoQuick precipitation methods.

MATERIALS AND METHODS

Rinsing separation utilizes heparin and glutaraldehyde as a fixative to isolate exosomes, and was developed using the culture supernatant from mesenchymal stem cells (MSCs). The isolated exosomes were characterized and compared by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and Western blot.

RESULTS

Consistent with known exosome parameters, exosomes isolated using each method ranged in size from 30 to 150 nm and demonstrated the characteristic cup-shaped morphology. Moreover, the exosome markers CD63 and TSG101 were observed in the lysate of all exosome samples that were isolated using each method. Several advantages and drawbacks were noted for each exosome isolation method. Most notably, ultracentrifugation resulted in fewer, but highly pure, exosomes, and samples generated using the ExoQuick precipitation method contained the most contaminating debris. Samples obtained using pour rinsing separation method represented an amalgam of these two fractions, but were isolated in significantly less time.

CONCLUSIONS

In this study, we propose rinsing separation as a new method of isolating exosomes. This method is convenient, and the resulting exosomes are highly pure. Moreover, rinsing separation offers time- and cost-efficiency advantages, making it a promising approach for exosome isolation for clinical applications.

Long noncoding RNA SNHG8 promotes the proliferation of osteosarcoma cells by downregulating miR-542-3p

Small nucleolar RNA host genes (SNHGs) as a subset of long noncoding RNAs (lncRNAs) have critical roles in the pathogenesis of multiple malignancies, however, the role and molecular mechanisms of lncRNA SNHG8 in osteosarcoma (OS) remain unclear. In the present study, the correlation of SNHG8 or miR-542-3p with clinicopathological elements and prognosis in OS patents was estimated by TCGA cohort. Cell viability and invasion were assessed by MTT and Transwell assays. The interplay between SNHG8 and miR-542-3p was affirmed by a luciferase report assay. The effects of SNHG8 on miR-542-3p expression were examined in MG-63 and SW-1353 cells by qRT-PCR analysis. The results showed that incremental expression of SNHG8 or reduced expression of miR-542-3p was related to poor survival and tumor recurrence in OS patients. Overexpressing SNHG8 accelerated the growth and invasion of MG-63 cells, but silencing SNHG8 harbored an opposite effect in SW-1353 cells. Additionally, SNHG8 could negatively regulate miR-542-3p expression and bind with miR-542-3p, which attenuated SNHG8 induced cell proliferation. Taken together, these findings indicate that lncRNA SNHG8 promotes the proliferation of OS cells by downregulating miR-542-3p.

P5397Mesenchymal stem cells derived from bone marrow promotes cardiomyocytes survival under hypoxia through exosomal miR-210

Background

A paracrine effect was regarded as the key mechanism involved in the MSC (mesenchymal stem cell)-based treatment for myocardial infarction. In our pilot experiments, hypoxia remarkably promotes MSC to paracrine exosomal miR-210, which could significantly enhance the cardiomyocytes survival in hypoxic incubation, suggesting that exosomal miR-210 played critical roles in the favorable paracrine effect of MSC on cardiomyocytes.

Purpose

The aim of this study was to investigate the important mechanism by which MSCs promote the tolerance of cardiomyocytes to hypoxia by secreting exosomal miR-210.

Methods and results

The exosomes were isolated from MSCs conditioned medium through ultracentrifugation, and we detected that miR-210 was the most abundant in MSC-exosome and increased most prominently in the hypoxia. The extracted exosomes were prepared for conditioned medium and the effect on myocardial protection was examined. The viability of control group was much better than the cardiomyocytes treated with hypoxia, but it was further increased in the presence of MSC-exosome, however, measurement was significantly lower in cardiomyocytes in hypoxia with exosomes derived from MSCs treated with GW4869. Subsequently, the co-localization of miR-210 with exosome-specific surface markers CD81 and CD63 were observed by immunofluorescence technique. Continuous magnetic live cell imaging was used to observe the uptake of exosome by cardiomyocytes, and fluorescence localization was used to observe the localization of miR-210 with Cy3 fluorescence in cardiomyocytes. Then, we demonstrated that MSCs exosomal miR-210 exerts the cardioprotective effect by regulating the AIFM3 (apoptosis-inducing factor mitochondria-associated protein 3), and we directly overexpressed miRNA-210 in cardiomyocytes and the results showed that the regulatory activity of the intake of exosomal miR-210 was consistent with that of the biological exosomal miR-210. Finally, we verified the protective effect on the ischemic myocardium by constructing rat myocardial infarction models. The level of apoptosis was detected at 1 week after myocardial infarction. The left ventricular ejection fraction and ventricular remodeling were measured at 4 weeks. In vivo, we demonstrated that explanted miR-210 from transplanted MSCs significantly reduced myocardial necrosis and apoptosis induced by ischemia and improved cardiac function and myocardial remodeling.

Conclusion

Here, we show that the exosomal miR-210 secreted by MSCs significantly increase the viability of cardiomyocytes and cardiac function. These findings suggest that exosomal miR-210 is a key effector that mediates the protection against hypoxia.

Acknowledgement/Funding

National Natural Science Foundation of China (Grant Nos. 81470467)

Permeability for horseradish peroxidase in strial capillaries in each turn of cochlea

The capillary permeability of the stria vascularis in each turn of cochlea was examined at intervals of 10 and 30 min and 1 and 2 h after an injection of horseradish peroxidase (HRP), using light and electron microscopic techniques. Ten minutes after HRP was administered, 18% of examined vessels showed HRP leakage. Thereafter, the level of HRP leakage increased with time. One hour after the injection, HRP had leaked from almost all vessels of the upper three turns. Two hours after the injection, the tracer in the vessel lumen became sparse with very thin staining or nonstaining, and a large amount of HRP was observed outside the vessels. It was noted that the capillary permeability to HRP at the basal turn was different from that of the upper three turns. This seems to be the result of the different pinocytic activity in the capillaries of these two regions. When the tracer disappeared from the vessels (2 h after the HRP injection), labelled vesicles in endothelial cells were frequently visible near the outside surface, whereas very few were visible near the inner surface. It is speculated, therefore, that HRP which has leaked can be reabsorbed back into the blood circulation via a similar micropinocytosis down the concentration gradient.