Increased serum level of Nup88 protein is associated with the development of colorectal cancer.

Nucleoporin88 (Nup88) has been shown to be overexpressed in a wide variety of malignancies including colorectal cancer (CRC). However, no study about serum Nup88 in human CRC was reported. Therefore, in this study, we investigated the level of serum Nup88 protein and its relationships with clinicopathological variables in CRC. The serum concentration of Nup88 protein was determined by a quantitative sandwich enzyme-linked immunosorbent assay (ELISA) in 118 pre-operative serum samples, 66 post-operative and 96 healthy controls. Among the patients, the levels of CEA (n = 91) and CA19-9 (n = 87) in the pre-operative serum were measured, and DNA sequencing was performed in 12 CRCs and 2 samples from non-cancerous colon tissue. In the same patients, the level of pre-operative serum Nup88 was significantly higher than that of post-operative Nup88 (P = 0.021). Furthermore, the level of pre-operative Nup88 was positively related to the depth of tumor invasion (P = 0.002) and advanced stage (P = 0.001). The level of pre-operative Nup88 in the left colon tended to be higher than that in the right colon and the rectum (P = 0.063). DNA sequencing results showed that there were two single nucleotide polymorphisms, distributed in exon 6 (NM_002532.3:c.1044G>A (ACG-ACA, Thr → Thr) and exon 10 (NM_002532.3:c.1389A>T, CCA-CCT, Pro → Pro). Serum Nup88 might be a candidate for a new biomarker implicated in the development and aggressiveness of CRCs.