Previous studies from this laboratory demonstrate that dietary leucine protects against high fat diet-induced mitochondrial impairments and stimulates mitochondrial biogenesis and energy partitioning from adipocytes to muscle cells through SIRT1-mediated mechanisms. Moreover, β-hydroxy-β-methyl butyrate (HMB), a metabolite of leucine, has been reported to activate AMPK synergistically with resveratrol in C2C12 myotubes. Therefore, we hypothesize that leucine-induced activation of SIRT1 and AMPK is the central event that links the upregulated mitochondrial biogenesis and fatty acid oxidation in skeletal muscle. Thus, C2C12 myotubes were treated with leucine (0.5 mM), alanine (0.5 mM), valine (0.5 mM), EX527 (SIRT1 inhibitor, 25 μM), and Compound C (AMPK inhibitor, 25 μM) alone or in combination to determine the roles of AMPK and SIRT1 in leucine-modulation of energy metabolism. Leucine significantly increased mitochondrial content, mitochondrial biogenesis-related genes expression, fatty acid oxidation, SIRT1 activity and gene expression, and AMPK phosphorylation in C2C12 myotubes compared to the controls, while EX527 and Compound C markedly attenuated these effects. Furthermore, leucine treatment for 24 hours resulted in time-dependent increases in cellular NAD+, SIRT1 activity, and p-AMPK level, with SIRT1 activation preceding that of AMPK, indicating that leucine activation of SIRT1, rather than AMPK, is the primary event.

Circular RNAs (circRNA), a class of noncoding RNAs, have been found to be involved in various diseases. Here, the expression levels of the circRNA hsa_circ_0001445 in 73 pairs of hepatocellular carcinoma (HCC) and adjacent nontumor tissues were investigated by quantitative real-time polymerase chain reaction (qRT-PCR). Our data demonstrate that the hsa_circ_0001445 levels were significantly decreased in HCC tissues (P < 0.001) and markedly associated with the number of tumor foci (P = 0.014). Furthermore, in vitro approaches showed that overexpression of hsa_circ_0001445 promoted apoptosis and inhibited proliferation, migration, and invasion of HCC-derived cells, suggesting that hsa_circ_0001445 might be involved in the development of HCC. In addition, we found that the plasma hsa_circ_0001445 transcription levels in HCC patients were lower than those in cirrhosis (P < 0.001) and hepatitis B (P < 0.001) patients as well as in healthy controls (P < 0.001). In fact, receiver operating characteristic curve analysis indicated that plasma hsa_circ_0001445 could be a fairly accurate marker to distinguish HCC cases from healthy controls as well as patients with cirrhosis or hepatitis B.

LncRNAs play critical roles in gastric cancer (GC). In this study, the expression of fourteen cancer related lncRNAs were investigated in paired tissues of 66 patients with GC, Realtime RT-PCR revealed that ZFAS1 was significantly upregulated. We then examined the expression of ZFAS1 in plasmas derived from 77 GC patients before- and post-operations and 60 healthy individuals, and found that circulating ZFAS1 was also upregulated in GC patients and operation can reduce its presence in plasma. To investigate the potential mechanisms, we compared the expression of ZFAS1 in multiple gastric cell lines and one normal cell line and found that ZFAS1 was up-regulated in GC cell lines. Furthermore, circulating tumor cells (CTC) were simulated by mixing GC cells with peripheral blood. After EpCAM antibody-based cell sorting, we found that the expression of ZFAS1 was positively correlated with EMT property of CTCs. In GC patient tissue samples, we found that Twist was positively correlated with ZFAS1 by immunohistochemical staining. Taken together, our results suggested that ZFAS1 was up-regulated in both tissues and plasmas of GC patients, and may be involved in regulation of EMT in GC progression. Thus, ZFAS1 might serve as a potential diagnostic marker and/or therapeutic target for GC.

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Non-small cell lung cancer (NSCLC) is one of the most malignant cancers in the world. Early diagnosis of NSCLC has become especially important for patient treatment and prognosis. Increasing evidence suggest that long non-coding RNA GAS5 plays vital roles in cancer proliferation and differentiation in NSCLC. However, its clinical value in the diagnosis of NSCLC is unclear. The objective of this study was to evaluate the importance of circulating GAS5 as a biomarker for NSCLC diagnosis. In our study, quantitative real-time PCR (QRT-PCR) was applied to detect the GAS5 expression level in 80 pairs of cancer tissues and 57 pairs of plasma samples of NSCLC patients. Further analysis was performed to study the differential expression of circulating GAS5 in 111 NSCLC patients and 78 healthy controls in our study. The results showed that GAS5 decreased in NSCLC tissues compared to noncancerous tissues (P<0.001). Furthermore, the GAS5 expression level was statistically declined in early stage of NSCLC before surgery compared with healthy controls (P<0.05) and sharply increased in postoperative groups (P=0.026). ROC curve analysis for early stage of NSCLC with the combination of GAS5, CEA and CA199 showed that the area under the ROC curve (AUC) was 0.734 (95% CI, 0.628‑0.839; P<0.0005). In conclusion, circulating GAS5 could be functioned as a potential combined biomarker for screening NSCLC and patient monitoring after surgical treatment.