Nanog, in Cooperation with AP1, Increases the Expression of E6/E7 Oncogenes from HPV Types 16/18

Abstract

Persistent infections with some types of human papillomavirus (HPV) constitute the major etiological factor for cervical cancer development. Nanog, a stem cell transcription factor has been shown to increase during cancer progression. We wanted to determine whether Nanog could modulate transcription of E6 and E7 oncogenes. We used luciferase reporters under the regulation of the long control region (LCR) of HPV types 16 and 18 (HPV16/18) and performed RT-qPCR. We found that Nanog increases activity of both viral regulatory regions and elevates endogenous E6/E7 mRNA levels in cervical cancer-derived cells. We demonstrated by in vitro mutagenesis that changes at Nanog-binding sites found in the HPV18 LCR significantly inhibit transcriptional activation. Chromatin immunoprecipitation (ChIP) assays showed that Nanog binds in vivo to the HPV18 LCR, and its overexpression increases its binding as well as that of c-Jun. Surprisingly, we observed that mutation of AP1-binding sites also affect Nanog’s ability to activate transcription, suggesting cooperation between the two factors. We searched for putative Nanog-binding sites in the LCR of several HPVs and surprisingly found them only in those types associated with cancer development. Our study shows, for the first time, a role for Nanog in the regulation of E6/E7 transcription of HPV16/18.

siRNA-E6 sensitizes HPV-16-related cervical cancer through Oxaliplatin: an in vitro study on anti-cancer combination therapy

“…CD133 has been the first potential cancer stem cells (CSC) marker in human cervical cancer, and also it has been reported that the CD44 marker plays a critical role in enriching the cervical CSC population [ 23 ]. One of the essential factors for stem cells is Nanog, which is involved in angiogenesis, multidrug resistance, lymph node metastasis, immune resistance, malignant progression, and invasion [ 24 ]. In this regard, our study’s results indicate that the colony formation rate following combination therapy with E6-siRNA and Oxaliplatin was significantly reduced compared to the control group.…”

“…Indeed, Nanog binds to the c-Jun promoter to increase c-Jun expression, which increases the expression of E6/E7 oncoproteins. In this regard, Díaz-Tejeda et al in 2021 reported that Nanog regulates E6 and E7 expression by binding to activator protein-1 (AP-1) [ 24 ]. In other words, the expression and activity of c-Jun are directly related to Nanog.…”

“…As a result, the activity of hr-HPV LCRs and the expression of E6 and E7 oncoproteins increased following the formation of AP-1 [ 26 , 27 ]. Therefore, Díaz-Tejeda et al showed that Nanog, as a transcription factor in stem cells, increased the activity of viral transcription regions and the expression level of E6/E7 oncogenes in cervical cancer cells [ 24 ]. On the other words, it has been reported that Nanog is involved in cervical cancer progression along with hr-HPV E6 and E7 oncoproteins as an essential factor for stem cells [ 24 ].…”

“…Therefore, Díaz-Tejeda et al showed that Nanog, as a transcription factor in stem cells, increased the activity of viral transcription regions and the expression level of E6/E7 oncogenes in cervical cancer cells [ 24 ]. On the other words, it has been reported that Nanog is involved in cervical cancer progression along with hr-HPV E6 and E7 oncoproteins as an essential factor for stem cells [ 24 ]. According to the results of our research, treatment with E6-siRNA and Oxaliplatin resulted in a significant reduction in Nanog expression consequently plummeting the ability of colony formation, metastasis, and eventually malignancy.…”