INTRACELLULAR EXPRESSION OF A SINGLE-CHAIN ANTIBODY-DIRECTED AGAINST HUMAN-PAPILLOMAVIRUS TYPE-16 E7 ONCOPROTEIN ACHIEVES TARGETED ANTINEOPLASTIC EFFECTS

Human papillomavirus type 16 (HPV16) E7 is a viral oncoprotein that is believed to play a major role in cervical neoplasia, Anti-HPV16 E7 in tracellular single-chain antibodies (scFvs) were constructed to downre gulate HPV16 E7 oncoprotein in HPV DNA-containing cell lines. In these studies, we transfected anti-E7 scFvs into the HPV16-positive human c ervical carcinoma cell lines CaSki and SiHa and tested them for their ability to inhibit cell proliferation and alter the level of HPV16 E7 oncoprotein. Our results showed that anti-HPV16 E7 scFvs inhibited cel l proliferation by >85% in CaSki cells and by 95% in SiHa cells. E7 on coprotein was down-regulated by anti-HPV16 E7 scFv, and its expression was inversely related to the amount of scFv transfected. However, the re were no effects of transfecting scFvs alone in HPV-negative cell li nes. These results imply that anti-HPV16 E7 scFvs only have specific a nti-HPV16 E7 effects on cell proliferation and on the synthesis of vir ally encoded proteins in HPV-positive cell lines. Thus, transfection o f HPV16 E7-positive tumors with antigen-specific scFvs may be a viable strategy for cervical cancer gene therapy.