Expression data from SIX1 knocked-down HKc/DR cells. Expression data from SIX1 knocked-down HKc/DR cells

The homeodomain transcription factor SIX1 plays a critical role in embryogenesis, is not expressed in normal adult tissue, but is expressed in many malignancies, including cervical cancer. SIX1 drives the progression of HPV16-immortalized human keratinocytes (HKc/HPV16) toward malignancy: HKc/HPV16 express high levels of SIX1 mRNA and protein; overexpression of SIX1 in HKc/HPV16 produces pre-malignant, differentiation-resistant lines (HKc/DR); SIX1 overexpression in HKc/DR induces tumorigenicity. In this paper, we explore the consequences of inhibition of SIX1 expression in premalignant HKc/DR. Only partial inhibition of SIX1 expression could be obtained in HKc/DR by RNA interference. Decreased SIX1 expression (up to 80%) in HKc/DR resulted in slower proliferation, decreased HPV16-E6/E7 mRNA levels, and increased p53 protein levels. Gene expression changes induced in HKc/DR by anti-SIX1 shRNA were indicative of mesenchymal-epithelial transition (EMT) and changes in TGF-beta signaling. We conclude that HPV16-transformed cells depend on SIX1 for survival, continuous HPV16 E6/E7 gene expression and EMT. Overall design: Three-condition, one-color experiment. HKc/DR cells were transfected with control or one of two different SIX1-targeting siRNA duplexes and gene expression was performed on RNA isolated from them. 4 biological replicates per each experimental group.