Clinical significance of the low expression of FER1L4 in gastric cancer patients.

Long non-coding RNA (lncRNA) is a new class of regulative non-coding RNA, with a length larger than 200 nucleotides. Recent studies found that there are close relations between disregulative lncRNAs and human tumors. However, the clinical significances are largely unknown. In this study, we investigated the lncRNA-Fer-1-like protein 4 (FER1L4) level in gastric cancer tissues and plasma. The FER1L4 level in human tissues and plasma were measured by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Then, the correlations between the tissue or plasma FER1L4 levels and clinicopathological factors were assessed. A receiver operating characteristic (ROC) curve was constructed for differentiating GC patients from controls. Compared to matched adjacent non-tumorous tissues, FER1L4 expression levels in 91.80 % (56/61) of gastric cancer tissues are significantly decreased. The low FER1L4 level were associated with tumor size (p < 0.001), histologic grade (p = 0.001), general classification (p < 0.001), depth of invasion (p < 0.001), lymphatic metastasis (p < 0.001), distant metastasis (p = 0.003), TNM stage (p < 0.001), vessel or nerve invasion (p < 0.001 or p = 0.003), and serum CA72-4 (p < 0.001). The area under the ROC curve (AUC) was up to 0.778 (p < 0.001) and the sensitivity and specificity were 67.2 and 80.3 %, respectively. Also, plasma FER1L4 was detected by qRT-PCR. Our data show that there was no difference of plasma FER1L4 level between healthy person and preoperative gastric cancer patients, with a sharp decline in 63.9 % (53/83) of gastric cancer patients 2 weeks after surgery (p = 0.028). Taken together, FER1L4 might play a crucial role in human gastric cancer and may be a new potential biomarker for clinical prognosis evaluation.