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To evaluate plasma chaperonin containing TCP1 complex subunit 3 (CCT3) and IQ-motif-containing GTPase-activating protein-3 (IQGAP3) as biomarker for hepatocellular carcinoma (HCC) screening and diagnosis.

Blood samples were collected from 126 HCC patients with HCC, 88 patients with cirrhosis and 50 healthy volunteers to detect plasma α-fetoprotein (AFP), CCT3 and IQGAP3 levels. Plasma AFP, CCT3 and IQGAP3 protein levels were measured by enzyme linked immunosorbent assay (ELISA).

In the plasma of HCC patients, both CCT3 and IQGAP3 were significantly higher than in patients with cirrhosis and in healthy controls (P < 0.01). CCT3 and IQGAP3 protein level correlated well with HCC etiology, tumor size, TNM stage, and child-pugh classification. CCT3 protein had higher sensitivity in the diagnosis of HCC when compared with AFP (87.3 vs 69.8 %). In addition, CCT3 and IQGAP3 protein were able to complement AFP in detecting AFP-negative HCC patients with sensitivity and specificity of 92.1 and 70.5 % and 81.6 and 71.6 %, respectively. In the small HCC group, CCT3 and IQGAP3 protein had sensitivity of 76.6 and 74.5 %, respectively. The combination of AFP + CCT3 + IQGAP3 (0.954) had significantly superior discriminative ability than AFP alone (0.815; P < 0.01).

CCT3 and IQGAP3 are novel complementary biomarkers for HCC screening and diagnosis, especially for AFP-negative and small HCC patients.