FIG 1.

Low DINO levels in HPV-positive cervical cancer cells are a result of E6-mediated TP53 inactivation. DINO levels in HPV-positive CaSki (HPV16), SiHa (HPV16), and HeLa (HPV18) and HPV-negative C33A cervical carcinoma cell lines were determined by quantitative reverse transcription-PCR (qRT-PCR) assays. DINO levels in control vector-transduced primary human foreskin keratinocytes (HFKs) and HPV16 E6/E7-expressing HFKs (16 E6/E7 HFKs) are shown for comparison (A). SiHa cells were transfected with an siRNA targeting HPV16 E6 alone or in combination with TP53 targeting siRNAs. HPV16 E6 and TP53 depletion was validated by measuring TP53 protein levels by immunoblotting (B) and by quantifying E6 mRNA levels by qRT-PCR (C). The TP53-dependent effects of HPV16 E6 depletion on DINO and the canonical TP53 transcriptional target CDKN1A were also assessed by qRT-PCR (C). Expression data are presented in arbitrary units (AU) and normalized to expression of the RPLP0 housekeeping gene. The positions of marker proteins with their apparent molecular weights in kilodaltons (kD) are indicated for the Western blots. Bar graphs represent means ± standard errors of the means (SEM) (n = 3). ***, P < 0.001; *, P < 0.05; ns, nonsignificant (Student’s t test).