Objective To investigate the relationships of the expression of serum long non-coding RNA FGD5-AS1 (lncRNA FGD5-AS1) and microRNA-133b (miR-133b) with clinicopathological features and prognosis in patients with colorectal cancer.

Methods A total of 85 patients with colorectal cancer were selected and assigned to colorectal cancer group, and postoperative cancer tissues and adjacent tissues were obtained. Another 85 healthy individuals who underwent physical examinations were selected as healthy group. The expression levels of lncRNA FGD5-AS1 and miR-133b in the serum of the two groups were compared, and the expression levels of lncRNA FGD5-AS1 and miR-133b in cancer tissues and adjacent tissues of patients were also compared. The correlation between the expression levels of lncRNA FGD5-AS1 and miR-133b, as well as their relationships with the prognosis of colorectal cancer patients were analyzed. The influencing factors for the 3-year prognosis of patients were screened, and the predictive efficacy of lncRNA FGD5-AS1 and miR-133b for the prognosis of patients with colorectal cancer was evaluated.

Results The expression level of serum lncRNA FGD5-AS1 in the colorectalcancer group was higher than that in the healthy group, while the expression level of miR-133b was lower than that in the healthy group (P < 0.05). In colorectal cancer tissues, the expression level of lncRNA FGD5-AS1 was higher than that in adjacent tissues, and the expression level of miR-133b was lower than that in adjacent tissues (P < 0.05). A negative correlation was observed between the expression of lncRNA FGD5-AS1 and miR-133b in the serum of patients with colorectal cancer (r=-0.402, P < 0.001). The expression levels of serum lncRNA FGD5-AS1 and miR-133b in patients were both associated with TNM stage, lymph node metastasis, and depth of tumor invasion (P < 0.05). The 3-year cumulative survival rate of patients with high expression of lncRNA FGD5-AS1 and low expression of miR-133b was lower than that of patients with low expression of lncRNA FGD5-AS1 and high expression of miR-133b, with a statistically significant difference (P < 0.05). LncRNA FGD5-AS1, miR-133b, TNM stage, and lymph node metastasis were all independent influencing factors for the 3-year prognosis of patients with colorectal cancer (P < 0.05). Receiver operating characteristic curve analysis showed that the area under the curve (AUC) for the combined prediction of the prognosis of patients with colorectal cancer by serum lncRNA FGD5-AS1 and miR-133b was 0.925, which was greater than the AUC for their individual predictions (P < 0.05).

Conclusion High expression of serum lncRNA FGD5-AS1 and low expression of miR-133b are observed in patients with colorectal cancer. The expression levels of these two molecules are associated with clinicopathological features and poor prognosis, indicating their potential predictive value for the prognosis of patients.