Open AccessRoles of the PDZ ‐binding motif of HPV 16 E6 protein in oncogenic transformation of human cervical keratinocytes
Author(s) -
Yoshimatsu Yuki,
Nakahara Tomomi,
Tanaka Katsuyuki,
Inagawa Yuki,
NarisawaSaito Mako,
Yugawa Takashi,
Ohno Shinichi,
Fujita Masatoshi,
Nakagama Hitoshi,
Kiyono Tohru
Publication year - 2017
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/cas.13264
Subject(s) - pdz domain , hras , carcinogenesis , microbiology and biotechnology , gene knockdown , mutant , transfection , biology , hek 293 cells , downregulation and upregulation , chemistry , cell culture , gene , biochemistry , mutation , genetics , kras
The high‐risk human papillomavirus E6 proteins have been shown to interact with and lead to degradation of PDZ ‐domain‐containing proteins through its carboxy‐terminal motif. This PDZ ‐binding motif plays important roles in transformation of cultured cells and carcinogenesis of E6‐transgenic mice. However, its biological effects on the natural host cells have not been elucidated. We have examined its roles in an in vitro carcinogenesis model for cervical cancer, in which E6 and E7 together with activated HRAS ( HRAS G 12V ) can induce tumorigenic transformation of normal human cervical keratinocytes. In this model, E6Δ151 mutant, which is defective in binding to PDZ domains, almost lost tumorigenic ability, whereas E6 SAT mutant, which is defective in p53 degradation showed activity close to wild‐type E6. Interestingly, we found decreased expression of PAR 3 in E6‐expressing cells independently of E6 AP , which has not been previously recognized. Therefore, we knocked down several PDZ ‐domain containing proteins including PAR 3 in human cervical keratinocytes expressing E7, HRAS G 12V and E6Δ151 to examine whether depletion of these proteins can restore the tumorigenic ability. Single knockdown of SCRIB , MAGI 1 or PAR 3 significantly but partially restored the tumorigenic ability. The combinatorial knockdown of SCRIB and MAGI 1 cooperatively restored the tumorigenic ability, and additional depletion of PAR 3 further enhanced the tumorigenic ability surpassing that induced by wild‐type E6. These data highlight the importance of the carboxy‐terminal motif of the E6 protein and downregulation of PAR 3 in tumorigenic transformation of human cervical keratinocytes.