Background: Glutaminase 2 (Gls2) is a p53 target gene and is known to play an important role in energy metabolism. Gls2 has been reported to be downregulated in human hepatocellular carcinomas (HCC). However, the underlying mechanism responsible for its downregulation is still unclear. Here, we investigated Gls2 expression and its promoter methylation status in human liver and colon cancers. Methods: mRNA expression of Gls2 was determined in human liver and colon cancer cell lines and HCC tissues by real-time PCR and promoter methylation was analyzed by methylation-specific PCR (MSP) and validated by bisulfite genome sequencing (BGS). Cell growth was determined by colony formation assay and MTS assay. Statistical analysis was performed by Wilcoxon matched-pairs test or non-parametric t test. Results: First, we observed reduced Gls2 mRNA level in a selected group of liver and colon cancer cell lines and in the cancerous tissues from 20 HCC and 5 human colon cancer patients in comparison to their non-cancerous counter parts. Importantly, the lower level of Gls2 in cancer cells was closely correlated to its promoter hypermethylation; and chemical demethylation treatment with 5-aza-2′-deoxycytidine (Aza) increased Gls2 mRNA level in both liver and colon cancer cells, indicating that direct epigenetic silencing suppressed Gls2 expression by methylation. Next, we further examined this correlation in human HCC tissues, and 60% of primary liver tumor tissues had higher DNA methylation levels when compared with adjacent non-tumor tissues. Detailed methylation analysis of 23 CpG sites at a 300-bp promoter region by bisulfite genomic sequencing confirmed its methylation. Finally, we examined the biological function of Gls2 and found that restoring Gls2 expression in cancer cells significantly inhibited cancer cell growth and colony formation ability through induction of cell cycle arrest. Conclusions: We provide evidence showing that epigenetic silencing of Gls2 via promoter hypermethylation is common in human liver and colon cancers and Gls2 appears to be a functional tumor suppressor involved in the liver and colon tumorigenesis.
Comparison of hepatic and serum lipid signatures in hepatocellular carcinoma patients leads to the discovery of diagnostic and prognostic biomarkers Comparison of hepatic and serum lipid signatures in hepatocellular carcinoma patients leads to the discovery of diagnostic and prognostic biomarkers
The Ebola virus disease spread rapidly in West Africa in 2014, leading to the loss of thousands of lives. Community engagement was one of the key strategies to interrupt Ebola transmission, and practical community level measures needed to be explored in the field and tailored to the specific context of communities. First, community-level education on Ebola virus disease (EVD) prevention was launched for the community’s social mobilizers in six districts in Sierra Leone beginning in November 2014. Then, from January to May of 2015, in three pilot communities, local trained community members were organized to engage in implementation of EVD prevention and transmission interruption measures, by involving them in alert case report, contact tracing, and social mobilization. The epidemiological indicators of transmission interruption in three study communities were evaluated. A total of 6 016 community social mobilizers from 185 wards were trained by holding 279 workshops in the six districts, and EVD message reached an estimated 631 680 residents. In three pilot communities, 72 EVD alert cases were reported, with 70.8 % of them detected by trained local community members, and 14 EVD cases were finally identified. Contact tracing detected 64.3 % of EVD cases. The median duration of community infectivity for the cases was 1 day. The secondary attack rate was 4.2 %, and no third generation of infection was triggered. No health worker was infected, and no unsafe burial and noncompliance to EVD control measures were recorded. The community-based measures were modeled to reduce 77 EVD cases, and the EVD-free goal was achieved four months earlier in study communities than whole country of Sierra Leone. The community-based strategy of social mobilization and community engagement was effective in case detection and reducing the extent of Ebola transmission in a country with weak health system. The successfully practical experience to reduce the risk of Ebola transmission in the community with poor resources would potentially be helpful for the global community to fight against the EVD and the other diseases in the future.