[Expression of long noncoding RNA STCAT3 in gastric cancer tissues and its effect on malignant phenotype of gastric cancer cells]

Objective: To detect the expression of long noncoding RNA(lncRNA)stomach cancer-associated transcript-3(STCAT3) in gastric cancer tissues, adjacent tissues, human gastric cancer cell lines and normal gastric epithelial cell lines, and to investigate the relationship between STCAT3 expression and clinicopathological features and malignant phenotype of gastric cancer. Methods: Quantitative fluorescent real-time polymerase chain reaction (qRT-PCR) was applied to detect the lncRNA STCAT3 expression levels in gastric cancer tissues, paired adjacent non-tumorous tissues, in order to explore the relationship between STCAT3 expression and clinicopathological features of gastric cancer. lncRNA STCAT3 low-expressing and high-expressing gastric cancer cell lines were transfected with expression plasmid to simulate gain-of-function, or interference plasmid to achieve loss-of-function. Cell proliferation was measured with CCK-8 and colony formation assay, cell migration with scratch assay, and cell invasion with Transwell migration assay. human gastric tumor were also transplanted to nude mice to detect the effect of lncRNA STCAT3 on tumorigenesis. Results: The expression of lncRNA STCAT3 was generally up-regulated in gastric cancer tissues compared with the adjacent tissues(12.55±0.16 vs 6.52±0.14), with median expression level in gastric cancer tissues being 6.03 higher (P<0.05). Meanwhile, the expression level of lncRNA STCAT3 in gastric cancer tissues was not correlated with age or gender (both P>0.05), while positively correlated with TNM stage (P<0.05). Interference of lncRNA STCAT3 expression in BGC-823 cells was found associated with significantly suppressed colony formation, proliferation, invasion, and migration (all P<0.05). Over-expression of lncRNA STCAT3 in AGS cells were also founded could promote the gastric cancer cells' proliferation, colony formation, migration, and invasion (all P<0.05). Conclusions: lncRNA STCAT3 may participate in the proliferation and invasion of gastric cancer cells, indicating that dysregulation of STCAT3 expression may play a role in occurrence and development of gastric cancer. lncRNA STCAT3 has the potential to be the biomarker of gastric cancer progression and target in treatment. The underlying mechanism is yet to be further studied.

Macrophage migration inhibitory factor is a direct target of HBP1-mediated transcriptional repression that is overexpressed in prostate cancer

Macrophage migration inhibitory factor (MIF) is a well-described proinflammatory mediator. MIF overexpression has been observed in many tumors and is implicated in oncogenic transformation and tumor progression. However, the molecular mechanisms responsible for regulating MIF expression remain poorly understood. In this study, we showed that the transcriptional repressor HBP1 (HMG box-containing protein 1) negatively regulates MIF expression. We first identified a large high-affinity HBP1 DNA-binding element at positions -811 to -792 from the transcriptional start site within the MIF promoter by computer analysis. Reporter analyses showed that this element was required for HBP1-mediated transcriptional repression. Furthermore, HBP1 associated with the MIF promoter in vivo and repressed endogenous MIF gene expression. Consistent with HBP1-mediated repression of MIF, low levels of HBP1 expression were associated with high levels of MIF expression in prostate cancer samples. Importantly, HBP1-mediated repression of MIF inhibited tumorigenic growth and invasion, and the repressive effect of HBP1 on tumorigenic growth and invasion could be partially rescued by the addition of recombinant MIF to the culture medium. Finally, prostate tumor samples with low HBP1 and high MIF expression were associated with a significant decrease in relapse-free survival. Taken together, these results indicated that HBP1 directly inhibited MIF gene transcription, and suggested that the loss of HBP1 expression or activity may contribute to the upregulation of MIF expression in prostate tumor tissue.