Clinical Utility of Serologic Diagnostic Markersusing HPV-16 Proteins in Cervical Neoplasia

Park, J S; Park, D C; Kim, C J; Ahn, H K; Park, S N; Jung, K T; Rhyu, W D; Kim, H S; Kim, S J; NamKoong, S E

Abstract

BACKGROUND: Most markers in current clinical use are not cancer-specific, but the ideal tumor marker should be specific for cancer, highly sensitive, clinically practicable, inexpensive, and acceptable to individual. it is still debating that SCCA and CEA are clinically useful for specific tumor markers in management of cervical cancers. Recently, a variety of HPV-related proteins have been synthesized and their utility as diagnostic and prognostic tumor markers in cervical cancers is needed to be assessed by comparing the previous tumor markers ; CEA and SCCA. The early proteins(E6 and E7) of HPV-16 which are responsible for malignant transformation could be constructed by in vitro transcription and translation and the late structural proteins(L1/L2) of HPV-16 have been shown to self-assemble into virus-like particles(VLPs) from baculovirus system when expressed in insect cells. The ability to generate preparative amounts of HPV-16 E6, E7 proteins and L1/L2 VLPs may have implications for the development of a serologic assay to detect anti-HPV-16 virion immune responses to conformational epitopes of HPV-associated cervical neoplasia.
METHODS
We attempted to investigate serologic response in the sera obtained from Korean women with cervical neoplasia by RIPA(radioimmunoprecipitation assay) using in vitro translated HPV-16 E6, E7 proteins and ELISA using HPV-16 L1/L2 VLPs, PCR method using E6 type-specific primers and probes for HPV-16/18 was used to determine the presence and type of HPV infection in the study population(normal controls ; 15 cases, preinvasive lesions ; 28 patients, and invasive cervical cancers; 124 cases). RESULT: 1) The sera of 0% of preinvasive lesions and 34%(42/124) of cervical cancers were positive for SCCA and the sera of 0% of preinvasive lesions and 18% (22/124) of cervical cancers were positive for CEA. The positivity of SCCA was increased with advancing clinical stages, but the antibody levels were not correlated with clinical outcome of disease. 2) The sera of 7%(2/28) of preinvasive lesions and 51%(63/124) of cervical cancers were positive for in vitro translated HPV-16 E6 protein(P < 0.05) and the sera of 11%(3/28) of preinvasive lesions and 33%(41/124) of cervical cancers were positive for in vitro translated HPV-16 E7 protein(P < 0.05). The levels of HPV-16 E6 proteins showed high titers in some invasive cancers, but they didn't show any fluctuations along with clinical outcomes. In contrast, the antibody levels to HPV-16 E7 protein were correlated to clinical stage and tumor burden in a significant number of cervical cancers. 3) The sera of 7% (1/15) of normal controls, 39%(11/28) of preinvasive lesions and 56% (70/124) of cervical cancers were ELISA positive for HPV-16 L1/L2 VLPs(P < 0.05). The positive reactivities for HPV-16 L1/L2 VLPs in cervical cancers by clinical stage, histopathology or HPV DNA types were not significantly different.
CONCLUSION
These results suggest that the considerable number of patients with cervical neoplasia generated positive antibody response to in vitro translated HPV-16 E6, E7 proteins and L1/L2 VLPs. These HPV-16-associated proteins might be disease-specific markers which could be useful in adjunctive diagnostic assay and seroepidemiologic study of HPV-related cervical neoplasia. Especially, the monitoring of antibody to HPV-16 E7 protein seems to be valuable in proper management of cervical cancers for specific tumor marker.