Detection and clinical application value of antimicrobial peptide hCAP18 in serum of colorectal carcinoma patients

Abstract

Objectve To evaluate the serum level of antimicrobial peptide human cationic antimicrobial protein 18 (hCAP18) in colorectal patients and it auxiliary diagnosis and prognosis value. Methods Case-control study was used. The serum level of hCAP18 was measured by enzyme linked immunosorbent assay(ELISA) in 68 cases with colorectal patients of department of gastrointestinal surgery and 40 cases healthy people of department of physical examination from January 2014 to June 2015 in Tongji Hosptial of Tongji University. The concentrations of hCAP18 in serum of colorectal patients before and surgery were analyzed. Immunohistochemistry was used to detect hCAP18 expression in colorectal carcinoma. The effect of hCAP18 on colon carcinoma cell proliferation was detected by BrdU-ELISA and soft agar colony formation assay. The sensitivity and specificity of serum hCAP18 for the diagnosis of colorectal were evaluated using the receiver operating characteristic curves(ROC) . Date was analyzed by using the t-test and one-way analysis of variance. Results hCAP18 serum levels in colon cancer of stage Ⅰ, Ⅱ, Ⅲ and IV patients were (0.46±0.18)mg/L, (0.65±0.45)mg/L, (1.26±0.68)mg/L and (2.35±1.06)mg/L. Mean value was(1.16±0.88) mg/L, which was significantly higher than in normal people (0.19±0.07)mg/L(t=5.290, P<0.05). hCAP18 levels had significantly decreased in serum of colorectal patients after 30 d surgery compared to preoperative results[from (1.16±0.88)mg/L to(0.26±0.06)mg/L; t=3.971, P<0.05]. Immunohistochemistry results showed hCAP18 was high expression in colon cancer tissue compared with adjacent tissues; BrdU-ELISA assay results showed HCT116 and SW480 cell proliferation increased significantly after 0.05-1 mg/L of hCAP18 treatment; Soft agar clone formation experiment proved hCAP18 could significant enhance clone formation of HCT116 and SW480 colon cancer cell lines. The size of clonal cluster of HCT116 was increased from (145.40±35.20)μm to(370.80±32.65)μm(t=10.50, P<0.05)and SW480 was increased from (101.00±27.10)μm to(369.00±27.29)μm(t=15.58, P<0.05); The numbers of clonal cluster of HCT116 was increased from 8.50±2.30 to 42.80±6.60(t=3.945, P<0.05)and SW480 was increased from 6.20±1.70 to 46.00±7.20(t=4.775, P<0.05). ROC analysis of serum hCAP18 yielded an AUC(area under the ROC curve) of 0.93(95% CI=0.859-0.999)with 91.17% sensitivity and 80.00% specificity, which was higher than the CEA[0.78 (95% CI=0.699-0.933)]. Conclousions Detection of serum hCAP18 shows a good sensitivity and specificity for the auxiliary diagnosis of colon cancer. It is possible to be potential detection index for noninvasive diagnosis and monitoring progression of colon cancer. hCAP18 could promote the proliferation of colon cancer cells, it played an important role in the progression of colon cancer.(Chin J Lab Med, 2017, 40: 278-283) Key words: Antimicrobial cationic peptides; Tumor markers, biological; Colonic neoplasms; Cell proliferation