Objective  To explore the diagnostic value of CD26 expression in endometrial carcinoma(EC)by testing CD26 expression innormal proliferative phase, in secretory phase, and in the tissues of different pathological grades of EC; and by investigating the soluble CD26(sCD26)expression in the serum of non-EC patients and EC patients.

  Methods  Endometrial tissue specimens were collectedfrom patients who received diagnostic curettage or surgical treatment for other reasons in the Affiliated Hospital of Nantong University from January 2014 to December 2015.The above endometrial specimens, included 30 specimens of normal proliferative phase, 30specimens of secretory phase, and 120 type I EC tissue samples of G1, G2, and G3 grades.The expression of CD26 among these specimens were detected by immunohistochemistry.After the expression level of the CD26 protein was verified at the tissue, we continuedto collect blood specimens from the outpatients.These patients received physical examination, and included healthy women of childbearing age and type I EC patients.The patients received treatment in our hospital from January 2016 to September 2017.Of theblood samples collected, 20 cases were in proliferative phase and 20 cases were in secretory phase.Samples were also collected frompatients with different grades of EC, including 20 cases of type I EC G1 grades, 20 cases of G2 grades, and 15 cases of G3 grades.Theexpression level of sCD26 in serum was detected by enzyme-linked immunosorbent assay(ELISA).

  Results  According to the results of immunohistochemistry, the order of the CD26 expression levels in normal endometrial tissues were as follows: secretory phase >proliferative phase, with a statistically significant difference observed among these groups(P < 0.05).The order of the CD26 expression levelamong different type 1 EC grades were as follows: G3>G2>G1, with statistically significant differences also observed among thesegroups(P < 0.05).The results of ELISA suggested that the expression level of CD26 in serum was associated with tumor progression, with statistically significant differences observed among the groups(P < 0.05).

  Conclusion  The expression of CD26 in EC tissue and serum is associated with disease progression.The expression of CD26 in serum could be used as a marker for the diagnosis of EC.Keywords: CD26, endometrial carcinoma, diagnosis, markers, tissue, serum