CRC is one of the most frequent malignancies in the digestive tract and contributes to part of cancer-related deaths worldwide. Though great progress has been achieved in CRC diagnosis, new and efficient method for early detection of CRC is still in urgent need owing to the detects of the existing screening methods . Nowadays, with the development of biotechnology, more and more investigations are focusing on biomarkers that could detect and predict CRC to improve the outcomes of CRC patients. It was claimed by Toiyama et al. that ANGPTL2 was linked to the migration of CRC and was a detector of CRC recurrence and diagnosis . Besides, Xiao et al. revealed that methylated NDRG4 acted as a diagnostic biomarker in CRC . However, this is far from enough to precisely diagnose CRC.
MiRNAs have been demonstrated to be significantly associated with the development and progression of various cancers as tumor suppressors or oncogenes [24, 25]. The potential roles of miRNAs in cancers make them promising biomarkers for prognosis and diagnosis of cancers. The aberrant expression of miRNAs has been detected in various cancers, such as miR-195 in non-small cell lung cancer, miR-372 in renal cell carcinoma and miR-128 in prostate cancer [26–28]. What’s more, current screening modalities for cancers mainly depends on tissue biopsy, magnetic resonance imaging (MRI) and computed tomography (CT), which are invasive and money consuming for patients. Therefore, more and more investigations are paying attention on serum detection, which is frugal and convenient. In the study of Jiang et al., down-regulation of serum miR-218 could act as a promising candidate in early diagnosis of esophageal cancer . Besides, Yu et al. observed that serum miR-218 levels were reduced in CRC patients compared healthy individuals, which represented a poor prognosis for patients . Therefore, in this study, we attempted to explore the relationship between miR-218 expression and CRC diagnosis.
We first compared the expression of serum miR-218 in CRC patients and healthy controls using qRT-PCR. The expression profile showed that the level of serum miR-218 was significantly lower in CRC cases than healthy controls, which was in accordance with the previous results, indicating miR-218 might be related to CRC progression. Then Chi-square test was adopted to analyze the relationship between miR-218 expression and clinical characteristics and miR-218 expression was influenced by lymph node metastasis, vascular invasion and TNM stage. Based on the above results, we hypothesized that miR-218 might play an important role in the diagnosis of CRC. Thereby, the ROC curve was established to validate our conjecture. And the result demonstrated miR-218 could serve as a diagnostic marker for CRC with high specificity and sensitivity.
In the present study, we stated a significant relationship between miR-218 expression and CRC diagnosis for the first time. However, to our best knowledge, the precise mechanism of miR-218 on CRC development and progression is still dismal. Wang et al. explained that miR-218 could suppress the proliferation, metastasis and EMT of gastric cancer cells through targeting WASF3 . Song et al. claimed that miR-218 impeded lung cancer growth via regulating MEF2D . In the study of Llm et al., miR-218 proved to regulate the expression of MACC1, which is a tumor suppressor in CRC . Moreover, evidence has indicated that a single miRNA might target on thousands of mRNAs . Thus, we conjectured miR-218 might function on CRC occurrence and development through targeting WASF3, MEF2D and MACC1, which needs verifying with more and further investigations in future.