Comparison of In Vitro Translated HPV-16 E7 Protein with GST-fusion HPV-16 E7 Protein in Clinical Utility as the Serologic Marker in the Patients with Cervical Cancer

Park, J S; Kim, T Y; Kim, E J; Kim, C J; Park, D C; Park, S H; Kim, S J; Namkoong, S E; Um, S J

Abstract

OBJECTIVE
Recently, a variety of HPV-related proteins have been synthesized and their utility as diagnostic and prognostic markers in cervical cancers is needed. The ability to generate preparative amounts of HPV-16 E7 proteins may have implications for the development of a serologic assay to detect anti-HPV-16 virion immune responses. The purpose of the study is to improve the way of proper management of the cervical cancer by investigating the clinical utility of in vitro translated HPV-16 E7 protein and GST-fusion HPV-16 E7 protein as the serologic marker through comparing the antibody reactions in the sera of the patients.
METHODS
The serologic responses were investigated in Korean women with cervical neoplasia by radioimmunoprecipitation assay (RIPA) using in vitro translated HPV-16 E7 protein and ELISA using GST-fusion HPV-16 E7 protein. PCR using E6 type-specific primers for HPV-16/18 were used to determine the presence and type of HPV infection (normal controls; 15 cases, preinvasive lesions; 15 cases, and invasive cervical cancers; HPV-16 DNA positive 78 cases and HPV-16 DNA negative 22 cases).
RESULTS
The sera of 39% (39/100) of patients with cervical cancer were RIPA positive for in vitro translated HPV-16 E7 protein [HPV-16 DNA positive cases; 41% (32/78), HPV-16 DNA negative cases; 32% (7/22)]. The sera of 29% (29/100) of cervical cancers were ELISA positive for HPV-16 GST-fusion E7 protein [HPV-16 DNA positive cases; 33% (26/78), HPV-16 DNA negative cases; 14% (3/22)]. By the two different methods, 12 cases were positively matched and 32 cases were negatively matched. The positivities for in vitrotranslated HPV-16 E7 protein in the patients with cervical cancer were 14% (7/49) in stage I, 59% (26/44) in stage II, and 86% (6/7) in stage III/IV, by significantly correlating with the advancing stage of the disease (P<0.01).
CONCLUSIONS
These data suggests that the considerable number of patients with cervical neoplasia generated positive antibody response to in vitro translated protein and GST-fusion protein of HPV-16 E7. In contrast to RIPA method using in vitro translated protein, ELISA method using GST-fusion protein has several advantages for clinical application; use of non-isotope, easy preparation to produce a sufficient of protein, available large scale study. But the positive rates to in vitro translated HPV-16 E7 protein in the patients of cervical cancer were higher in general than those to GST-fusion HPV-16 proteins. Furthermore, the antibody positivities to in vitro translated HPV-16 E7 protein were increased by advancing clinical stage of disease. These HPV-16 E7 proteins might be the disease-specific markers which could be useful in adjunctive diagnostic assay and seroepidemiologic study of HPV-related cervical neoplasia.