No abstract

Exosomal microRNAs have recently been studied as the potential diagnostic marker for various malignancies, including hepatocellular carcinoma (HCC). The aim of this study was to investigate serum exosomal microRNA profiles as HCC diagnostic marker. Transmission electron microscopy and Western blot were used to identify serum exosomes. Deep sequencing was performed to screen differentially expressed microRNAs between HCC (n = 5) and liver cirrhosis (LC, n = 5) groups. Three upregulated and two downregulated microRNAs were selected for qPCR analysis. The levels of selected microRNAs were normalized to Caenorhabditis elegans miR‐39 microRNA mimics. Serum exosomal level of miR‐122, miR‐148a, and miR‐1246 was further analyzed and significantly higher in HCC than LC and normal control (NC) groups (P < 0.001), but not different from chronic hepatitis group (P > 0.05). The receiver operating characteristic curve was used to evaluate the diagnostic performance of candidate microRNAs. Area under the curve (AUC) of miR‐148a was 0.891 [95% confidence interval (CI), 0.809–0.947] in discriminating HCC from LC, remarkably higher than alpha‐fetoprotein (AFP) (AUC: 0.712, 95% CI: 0.607–0.803). Binary logistic regression was adopted to establish the diagnostic model for discriminating HCC from LC. And the combination of miR‐122, miR‐148a, and AFP increased the AUC to 0.931 (95% CI, 0.857–0.973), which can also be applied for distinguishing early HCC from LC. miR‐122 was the best for differentiating HCC from NC (AUC: 0.990, 95% CI, 0.945–1.000). These data suggest that serum exosomal microRNAs signature or their combination with traditional biomarker may be used as a suitable peripheral screening tool for HCC.

The second messenger cyclic adenosine monophosphate (cAMP) plays an important role in cell proliferation, differentiation and apoptosis. In the present work, we evaluated the cAMP signaling in acute promyelocytic leukemia (APL) cells in the context of differentiation induced by all-trans retinoic acid (ATRA). There was a marked increase in the intracellular cAMP level within a few minutes after treatment with ATRA in APL cell line NB4 and fresh APL cells, whereas no such phenomenon was observed in NB4-R1 cells that are resistant to ATRAinduced maturation. In addition, the basal level of intracellular cAMP was lower in NB4-R1 than in NB4 cells. Mechanistic study showed that this induction of cAMP was mediated through the activation of adenylate cyclase. Moreover, we found that cAMPdependent protein kinase (PKA) activity was quickly upregulated in parallel in ATRA-treated NB4 cells, and the phosphorylation of RARa by PKA could increase its transactivation effect. Use of H-89, an inhibitor of PKA, could partially suppress the transcriptional expression of ATRA target genes and ATRAinduced differentiation of APL cells. Taken together, we suggested a crosstalk between ATRA-induced cytosolic pathway and nuclear pathway in APL cell differentiation.